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Bibliography on: Endosymbiosis

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ESP: PubMed Auto Bibliography 16 Jan 2019 at 01:43 Created: 


A symbiotic relationship in which one of the partners lives within the other, especially if it lives within the cells of the other, is known as endosymbiosis. Mitochondria, chloroplasts, and perhaps other cellular organelles are believed to have originated from a form of endosymbiosis. The endosymbiotic origin of eukaryotes seems to have been a biological singularity — that is, it happened once, and only once, in the history of life on Earth.

Created with PubMed® Query: endosymbiont NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2019-01-12

Brinkmann A, Hekimoğlu O, Dinçer E, et al (2019)

A cross-sectional screening by next-generation sequencing reveals Rickettsia, Coxiella, Francisella, Borrelia, Babesia, Theileria and Hemolivia species in ticks from Anatolia.

Parasites & vectors, 12(1):26 pii:10.1186/s13071-018-3277-7.

BACKGROUND: Ticks participate as arthropod vectors in the transmission of pathogenic microorganisms to humans. Several tick-borne infections have reemerged, along with newly described agents of unexplored pathogenicity. In an attempt to expand current information on tick-associated bacteria and protozoans, we performed a cross-sectional screening of ticks, using next-generation sequencing. Ticks seeking hosts and infesting domestic animals were collected in four provinces across the Aegean, Mediterranean and Central Anatolia regions of Turkey and analyzed by commonly used procedures and platforms.

RESULTS: Two hundred and eighty ticks comprising 10 species were evaluated in 40 pools. Contigs from tick-associated microorganisms were detected in 22 (55%) questing and 4 feeding (10%) tick pools, with multiple microorganisms identified in 12 pools. Rickettsia 16S ribosomal RNA gene, gltA, sca1 and ompA sequences were present in 7 pools (17.5%), comprising feeding Haemaphysalis parva and questing/hunting Rhipicephalus bursa, Rhipicephalus sanguineus (sensu lato) and Hyalomma marginatum specimens. A near-complete genome and conjugative plasmid of a Rickettsia hoogstraalii strain could be characterized in questing Ha. parva. Coxiella-like endosymbionts were identified in pools of questing (12/40) as well as feeding (4/40) ticks of the genera Rhipicephalus, Haemaphysalis and Hyalomma. Francisella-like endosymbionts were also detected in 22.5% (9/40) of the pools that comprise hunting Hyalomma ticks in 8 pools. Coxiella-like and Francisella-like endosymbionts formed phylogenetically distinct clusters associated with their tick hosts. Borrelia turcica was characterized in 5% (2/40) of the pools, comprising hunting Hyalomma aegyptium ticks. Co-infection of Coxiella-like endosymbiont and Babesia was noted in a questing R. sanguineus (s.l.) specimen. Furthermore, protozoan 18S rRNA gene sequences were detected in 4 pools of questing/hunting ticks (10%) and identified as Babesia ovis, Hemolivia mauritanica, Babesia and Theileria spp.

CONCLUSIONS: Our metagenomic approach enabled identification of diverse pathogenic and non-pathogenic microorganisms in questing and feeding ticks in Anatolia.

RevDate: 2019-01-10

Ševcíková T, Yurchenko T, Fawley KP, et al (2019)

Plastid genomes and proteins illuminate the evolution of eustigmatophyte algae and their bacterial endosymbionts.

Genome biology and evolution pii:5284916 [Epub ahead of print].

Eustigmatophytes, a class of stramenopile algae (ochrophytes), include not only the extensively studied biotechnologically important genus Nannochloropsis, but also a rapidly expanding diversity of lineages with much less well characterized biology. Recent discoveries have led to exciting additions to our knowledge about eustigmatophytes. Some proved to harbour bacterial endosymbionts representing a novel genus Candidatus Phycorickettsia, and an operon of unclear function (ebo) obtained by horizontal gene transfer (HGT) from the endosymbiont lineage was found in the plastid genomes of still other eustigmatophytes. To shed more light on the latter event, as well as to generally improve our understanding of the eustigmatophyte evolutionary history, we sequenced plastid genomes of seven phylogenetically diverse representatives (including new isolates representing undescribed taxa). A phylogenomic analysis of plastid genome-encoded proteins resolved the phylogenetic relationships among the main eustigmatophyte lineages and provided a framework for the interpretation of plastid gene gains and losses in the group. The ebo operon gain was inferred to have probably occurred within the order Eustigmatales, after the divergence of the two basalmost lineages (a newly discovered hitherto undescribed strain and the Pseudellipsoidion group). When looking for nuclear genes potentially compensating for plastid gene losses, we noticed a gene for a plastid-targeted acyl carrier protein that was apparently acquired by HGT from Phycorickettsia. The presence of this gene in all eustigmatophytes studied, including representatives of both principal clades (Eustigmatales and Goniochloridales), is a genetic footprint indicating that the eustigmatophyte-Phycorickettsia partnership started no later than in the last eustigmatophyte common ancestor.

RevDate: 2019-01-10

Fokin SI, Serra V, Ferrantini F, et al (2019)

"Candidatus Hafkinia simulans" gen. nov., sp. nov., a Novel Holospora-Like Bacterium from the Macronucleus of the Rare Brackish Water Ciliate Frontonia salmastra (Oligohymenophorea, Ciliophora): Multidisciplinary Characterization of the New Endosymbiont and Its Host.

Microbial ecology pii:10.1007/s00248-018-1311-0 [Epub ahead of print].

We characterized a novel Holospora-like bacterium (HLB) (Alphaproteobacteria, Holosporales) living in the macronucleus of the brackish water ciliate Frontonia salmastra. This bacterium was morphologically and ultrastructurally investigated, and its life cycle and infection capabilities were described. We also obtained its 16S rRNA gene sequence and performed in situ hybridization experiments with a specifically-designed probe. A new taxon, "Candidatus Hafkinia simulans", was established for this HLB. The phylogeny of the family Holosporaceae based on 16S rRNA gene sequences was inferred, adding to the already available data both the sequence of the novel bacterium and those of other Holospora and HLB species recently characterized. Our phylogenetic analysis provided molecular support for the monophyly of HLBs and placed the new endosymbiont as the sister genus of Holospora. Additionally, the host ciliate F. salmastra, recorded in Europe for the first time, was concurrently described through a multidisciplinary study. Frontonia salmastra's phylogenetic position in the subclass Peniculia and the genus Frontonia was assessed according to 18S rRNA gene sequencing. Comments on the biodiversity of this genus were added according to past and recent literature.

RevDate: 2019-01-08

Garcia GA, Sylvestre G, Aguiar R, et al (2019)

Matching the genetics of released and local Aedes aegypti populations is critical to assure Wolbachia invasion.

PLoS neglected tropical diseases, 13(1):e0007023 pii:PNTD-D-18-01360 [Epub ahead of print].

BACKGROUND: Traditional vector control approaches such as source reduction and insecticide spraying have limited effect on reducing Aedes aegypti population. The endosymbiont Wolbachia is pointed as a promising tool to mitigate arbovirus transmission and has been deployed worldwide. Models predict a rapid increase on the frequency of Wolbachia-positive Aedes aegypti mosquitoes in local settings, supported by cytoplasmic incompatibility (CI) and high maternal transmission rate associated with the wMelBr strain.

Wolbachia wMelBr strain was released for 20 consecutive weeks after receiving >87% approval of householders of the isolated community of Tubiacanga, Rio de Janeiro. wMelBr frequency plateued~40% during weeks 7-19, peaked 65% but dropped as releases stopped. A high (97.56%) maternal transmission was observed. Doubling releases and deploying mosquitoes with large wing length and low laboratory mortality produced no detectable effects on invasion trend. By investigating the lab colony maintenance procedures backwardly, pyrethroid resistant genotypes in wMelBr decreased from 68% to 3.5% after 17 generations. Therefore, we initially released susceptible mosquitoes in a local population highly resistant to pyrethroids which, associated with the over use of insecticides by householders, ended jeopardizing Wolbachia invasion. A new strain (wMelRio) was produced after backcrossing wMelBr females with males from field to introduce mostly pyrethroid resistance alleles. The new strain increased mosquito survival but produced relevant negative effects on Ae. aegypti fecundity traits, reducing egg clutche size and egg hatch. Despite the cost on fitness, wMelRio successful established where wMelBr failed, revealing that matching the local population genetics, especially insecticide resistance background, is critical to achieve invasion.

CONCLUSIONS/SIGNIFICANCE: Local householders support was constantly high, reaching 90% backing on the second release (wMelRio strain). Notwithstanding the drought summer, the harsh temperature recorded (daily average above 30°C) did not seem to affect the expression of maternal transmission of wMel on a Brazilian background. Wolbachia deployment should match the insecticide resistance profile of the wild population to achieve invasion. Considering pyrethroid-resistance is a widely distributed phenotype in natural Ae. aegypti populations, future Wolbachia deployments must pay special attention in maintaining insecticide resistance in lab colonies for releases.

RevDate: 2019-01-08

Li S, Liu D, Zhang R, et al (2018)

Effects of a presumably protective endosymbiont on life-history characters and their plasticity for its host aphid on three plants.

Ecology and evolution, 8(24):13004-13013 pii:ECE34754.

Hamiltonella defensa is well known for its protective roles against parasitoids for its aphid hosts, but its functional roles in insect-plant interactions are less understood. Thus, the impact of H. defensa infections on life-history characters and the underlying genetic variation for the grain aphid, Sitobion avenae (Fabricius), was explored on three plants (i.e., wheat, oat, and rye). Compared to cured lines, H. defensa infected lines of S. avenae had lower fecundity on wheat and oat, but not on rye, suggesting an infection cost for the aphid on susceptible host plants. However, when tested on rye, the infected lines showed a shorter developmental time for the nymphal stage than corresponding cured lines, showing some benefit for S. avenae carrying the endosymbiont on resistant host plants. The infection of H. defensa altered genetic variation underlying its host S. avenea's life-history characters, which was shown by differences in heritabilities and genetic correlations of life-history characters between S. avenae lines infected and cured of the endosymbiont. This was further substantiated by disparity in G-matrices of their life-history characters for the two types of aphid lines. The G-matrices for life-history characters of aphid lines infected with and cured of H. defensa were significantly different from each other on rye, but not on oat, suggesting strong plant-dependent effects. The developmental durations of infected S. avenae lines showed a lower plasticity compared with those of corresponding cured lines, and this could mean higher adaptability for the infected lines.Overall, our results showed novel functional roles of a common secondary endosymbiont (i.e., H. defensa) in plant-insect interactions, and its infections could have significant consequences for the evolutionary ecology of its host insect populations in nature.

RevDate: 2019-01-08

Brenner WG, Mader M, Müller NA, et al (2019)

High Level of Conservation of Mitochondrial RNA Editing Sites Among Four Populus Species.

G3 (Bethesda, Md.) pii:g3.118.200763 [Epub ahead of print].

RNA editing occurs in the endosymbiont organelles of higher plants as C-to-U conversions of defined nucleotides. The availability of large quantities of RNA sequencing data makes it possible to identify RNA editing sites and to quantify their editing extent. We have investigated RNA editing in 34 protein-coding mitochondrial transcripts of four Populus species, a genus noteworthy for its remarkably small number of RNA editing sites compared to other angiosperms. 27 of these transcripts were subject to RNA editing in at least one species. In total, 355 RNA editing sites were identified with high confidence, their editing extents ranging from 10 to 100%. The most heavily edited transcripts were ccmC with the highest density of RNA editing sites (50.5 sites / kb) and ccmFn with the highest number of sites (39 sites). Most of the editing events are at position 1 or 2 of the codons, usually altering the encoded amino acid, and are highly conserved among the species, also with regard to their editing extent. However, one SNP was found in the newly sequenced and annotated mitochondrial genome of P. alba resulting in the loss of an RNA editing site compared to P. tremula and P. davidiana This SNP causes a C-to-T transition and an amino acid exchange from Ser to Phe, highlighting the widely discussed role of RNA editing in compensating mutations.

RevDate: 2019-01-08

Hong WD, Benayoud F, Nixon GL, et al (2019)

AWZ1066S, a highly specific anti-Wolbachia drug candidate for a short-course treatment of filariasis.

Proceedings of the National Academy of Sciences of the United States of America pii:1816585116 [Epub ahead of print].

Onchocerciasis and lymphatic filariasis are two neglected tropical diseases that together affect ∼157 million people and inflict severe disability. Both diseases are caused by parasitic filarial nematodes with elimination efforts constrained by the lack of a safe drug that can kill the adult filaria (macrofilaricide). Previous proof-of-concept human trials have demonstrated that depleting >90% of the essential nematode endosymbiont bacterium, Wolbachia, using antibiotics, can lead to permanent sterilization of adult female parasites and a safe macrofilaricidal outcome. AWZ1066S is a highly specific anti-Wolbachia candidate selected through a lead optimization program focused on balancing efficacy, safety and drug metabolism/pharmacokinetic (DMPK) features of a thienopyrimidine/quinazoline scaffold derived from phenotypic screening. AWZ1066S shows superior efficacy to existing anti-Wolbachia therapies in validated preclinical models of infection and has DMPK characteristics that are compatible with a short therapeutic regimen of 7 days or less. This candidate molecule is well-positioned for onward development and has the potential to make a significant impact on communities affected by filariasis.

RevDate: 2019-01-07

Ye S, Bhattacharjee M, E Siemann (2019)

Thermal Tolerance in Green Hydra: Identifying the Roles of Algal Endosymbionts and Hosts in a Freshwater Holobiont Under Stress.

Microbial ecology pii:10.1007/s00248-018-01315-1 [Epub ahead of print].

It has been proposed that holobionts (host-symbiont units) could swap endosymbionts, rapidly alter the hologenome (host plus symbiont genome), and increase their stress tolerance. However, experimental tests of individual and combined contributions of hosts and endosymbionts to holobiont stress tolerance are needed to test this hypothesis. Here, we used six green hydra (Hydra viridissima) strains to tease apart host (hydra) and symbiont (algae) contributions to thermal tolerance. Heat shock experiments with (1) hydra with their original symbionts, (2) aposymbiotic hydra (algae removed), (3) novel associations (a single hydra strain hosting different algae individually), and (4) control hydra (aposymbiotic hydra re-associated with their original algae) showed high variation in thermal tolerance in each group. Relative tolerances of strains were the same within original, aposymbiotic, and control treatments, but reversed in the novel associations group. Aposymbiotic hydra had similar or higher thermal tolerance than hydra with algal symbionts. Selection on the holobiont appears to be stronger than on either partner alone, suggesting endosymbiosis could become an evolutionary trap under climate change. Our results suggest that green hydra thermal tolerance is strongly determined by the host, with a smaller, non-positive role for the algal symbiont. Once temperatures exceed host tolerance limits, swapping symbionts is unlikely to allow these holobionts to persist. Rather, increases in host tolerance through in situ adaptation or migration of pre-adapted host strains appear more likely to increase local thermal tolerance. Overall, our results indicate green hydra is a valuable system for studying aquatic endosymbiosis under changing environmental conditions, and demonstrate how the host and the endosymbiont contribute to holobiont stress tolerance.

RevDate: 2019-01-06

Kamm K, Schierwater B, R DeSalle (2019)

Innate immunity in the simplest animals - placozoans.

BMC genomics, 20(1):5 pii:10.1186/s12864-018-5377-3.

BACKGROUND: Innate immunity provides the core recognition system in animals for preventing infection, but also plays an important role in managing the relationship between an animal host and its symbiont. Most of our knowledge about innate immunity stems from a few animal model systems, but substantial variation between metazoan phyla has been revealed by comparative genomic studies. The exploration of more taxa is still needed to better understand the evolution of immunity related mechanisms. Placozoans are morphologically the simplest organized metazoans and the association between these enigmatic animals and their rickettsial endosymbionts has recently been elucidated. Our analyses of the novel placozoan nuclear genome of Trichoplax sp. H2 and its associated rickettsial endosymbiont genome clearly pointed to a mutualistic and co-evolutionary relationship. This discovery raises the question of how the placozoan holobiont manages symbiosis and, conversely, how it defends against harmful microorganisms. In this study, we examined the annotated genome of Trichoplax sp. H2 for the presence of genes involved in innate immune recognition and downstream signaling.

RESULTS: A rich repertoire of genes belonging to the Toll-like and NOD-like receptor pathways, to scavenger receptors and to secreted fibrinogen-related domain genes was identified in the genome of Trichoplax sp. H2. Nevertheless, the innate immunity related pathways in placozoans deviate in several instances from well investigated vertebrates and invertebrates. While true Toll- and NOD-like receptors are absent, the presence of many genes of the downstream signaling cascade suggests at least primordial Toll-like receptor signaling in Placozoa. An abundance of scavenger receptors, fibrinogen-related domain genes and Apaf-1 genes clearly constitutes an expansion of the immunity related gene repertoire specific to Placozoa.

CONCLUSIONS: The found wealth of immunity related genes present in Placozoa is surprising and quite striking in light of the extremely simple placozoan body plan and their sparse cell type makeup. Research is warranted to reveal how Placozoa utilize this immune repertoire to manage and maintain their associated microbiota as well as to fend-off pathogens.

RevDate: 2019-01-05

Bustamante-Brito R, Vera-Ponce de León A, Rosenblueth M, et al (2019)

Metatranscriptomic Analysis of the Bacterial Symbiont Dactylopiibacterium carminicum from the Carmine Cochineal Dactylopius coccus (Hemiptera: Coccoidea: Dactylopiidae).

Life (Basel, Switzerland), 9(1): pii:life9010004.

The scale insect Dactylopius coccus produces high amounts of carminic acid, which has historically been used as a pigment by pre-Hispanic American cultures. Nowadays carmine is found in food, cosmetics, and textiles. Metagenomic approaches revealed that Dactylopius spp. cochineals contain two Wolbachia strains, a betaproteobacterium named Candidatus Dactylopiibacterium carminicum and Spiroplasma, in addition to different fungi. We describe here a transcriptomic analysis indicating that Dactylopiibacterium is metabolically active inside the insect host, and estimate that there are over twice as many Dactylopiibacterium cells in the hemolymph than in the gut, with even fewer in the ovary. Albeit scarce, the transcripts in the ovaries support the presence of Dactylopiibacterium in this tissue and a vertical mode of transmission. In the cochineal, Dactylopiibacterium may catabolize plant polysaccharides, and be active in carbon and nitrogen provisioning through its degradative activity and by fixing nitrogen. In most insects, nitrogen-fixing bacteria are found in the gut, but in this study they are shown to occur in the hemolymph, probably delivering essential amino acids and riboflavin to the host from nitrogen substrates derived from nitrogen fixation.

RevDate: 2019-01-03

Vera-Ponce de León A, Ormeño-Orrillo E, Ramírez-Puebla ST, et al (2017)

Candidatus Dactylopiibacterium carminicum, a Nitrogen-Fixing Symbiont of Dactylopius Cochineal Insects (Hemiptera: Coccoidea: Dactylopiidae).

Genome biology and evolution, 9(9):2237-2250 pii:4091605.

The domesticated carmine cochineal Dactylopius coccus (scale insect) has commercial value and has been used for more than 500 years for natural red pigment production. Besides the domesticated cochineal, other wild Dactylopius species such as Dactylopius opuntiae are found in the Americas, all feeding on nutrient poor sap from native cacti. To compensate nutritional deficiencies, many insects harbor symbiotic bacteria which provide essential amino acids or vitamins to their hosts. Here, we characterized a symbiont from the carmine cochineal insects, Candidatus Dactylopiibacterium carminicum (betaproteobacterium, Rhodocyclaceae family) and found it in D. coccus and in D. opuntiae ovaries by fluorescent in situ hybridization, suggesting maternal inheritance. Bacterial genomes recovered from metagenomic data derived from whole insects or tissues both from D. coccus and from D. opuntiae were around 3.6 Mb in size. Phylogenomics showed that dactylopiibacteria constituted a closely related clade neighbor to nitrogen fixing bacteria from soil or from various plants including rice and other grass endophytes. Metabolic capabilities were inferred from genomic analyses, showing a complete operon for nitrogen fixation, biosynthesis of amino acids and vitamins and putative traits of anaerobic or microoxic metabolism as well as genes for plant interaction. Dactylopiibacterium nif gene expression and acetylene reduction activity detecting nitrogen fixation were evidenced in D. coccus hemolymph and ovaries, in congruence with the endosymbiont fluorescent in situ hybridization location. Dactylopiibacterium symbionts may compensate for the nitrogen deficiency in the cochineal diet. In addition, this symbiont may provide essential amino acids, recycle uric acid, and increase the cochineal life span.

RevDate: 2019-01-03

Clare RH, Bardelle C, Harper P, et al (2019)

Industrial scale high-throughput screening delivers multiple fast acting macrofilaricides.

Nature communications, 10(1):11 pii:10.1038/s41467-018-07826-2.

Nematodes causing lymphatic filariasis and onchocerciasis rely on their bacterial endosymbiont, Wolbachia, for survival and fecundity, making Wolbachia a promising therapeutic target. Here we perform a high-throughput screen of AstraZeneca's 1.3 million in-house compound library and identify 5 novel chemotypes with faster in vitro kill rates (<2 days) than existing anti-Wolbachia drugs that cure onchocerciasis and lymphatic filariasis. This industrial scale anthelmintic neglected tropical disease (NTD) screening campaign is the result of a partnership between the Anti-Wolbachia consortium (A∙WOL) and AstraZeneca. The campaign was informed throughout by rational prioritisation and triage of compounds using cheminformatics to balance chemical diversity and drug like properties reducing the chance of attrition from the outset. Ongoing development of these multiple chemotypes, all with superior time-kill kinetics than registered antibiotics with anti-Wolbachia activity, has the potential to improve upon the current therapeutic options and deliver improved, safer and more selective macrofilaricidal drugs.

RevDate: 2019-01-03

Hall RJ, Flanagan LA, Bottery MJ, et al (2019)

A Tale of Three Species: Adaptation of Sodalis glossinidius to Tsetse Biology, Wigglesworthia Metabolism, and Host Diet.

mBio, 10(1): pii:mBio.02106-18.

The tsetse fly is the insect vector for the Trypanosoma brucei parasite, the causative agent of human African trypanosomiasis. The colonization and spread of the trypanosome correlate positively with the presence of a secondary symbiotic bacterium, Sodalis glossinidius The metabolic requirements and interactions of the bacterium with its host are poorly understood, and herein we describe a metabolic model of S. glossinidius metabolism. The model enabled the design and experimental verification of a defined medium that supports S. glossinidius growth ex vivo This has been used subsequently to analyze in vitro aspects of S. glossinidius metabolism, revealing multiple unique adaptations of the symbiont to its environment. Continued dependence on a sugar, and the importance of the chitin monomer N-acetyl-d-glucosamine as a carbon and energy source, suggests adaptation to host-derived molecules. Adaptation to the amino acid-rich blood diet is revealed by a strong dependence on l-glutamate as a source of carbon and nitrogen and by the ability to rescue a predicted l-arginine auxotrophy. Finally, the selective loss of thiamine biosynthesis, a vitamin provided to the host by the primary symbiont Wigglesworthia glossinidia, reveals an intersymbiont dependence. The reductive evolution of S. glossinidius to exploit environmentally derived metabolites has resulted in multiple weaknesses in the metabolic network. These weaknesses may become targets for reagents that inhibit S. glossinidius growth and aid the reduction of trypanosomal transmission.IMPORTANCE Human African trypanosomiasis is caused by the Trypanosoma brucei parasite. The tsetse fly vector is of interest for its potential to prevent disease spread, as it is essential for T. brucei life cycle progression and transmission. The tsetse's mutualistic endosymbiont Sodalis glossinidius has a link to trypanosome establishment, providing a disease control target. Here, we describe a new, experimentally verified model of S. glossinidius metabolism. This model has enabled the development of a defined growth medium that was used successfully to test aspects of S. glossinidius metabolism. We present S. glossinidius as uniquely adapted to life in the tsetse, through its reliance on the blood diet and host-derived sugars. Additionally, S. glossinidius has adapted to the tsetse's obligate symbiont Wigglesworthia glossinidia by scavenging a vitamin it produces for the insect. This work highlights the use of metabolic modeling to design defined growth media for symbiotic bacteria and may provide novel inhibitory targets to block trypanosome transmission.

RevDate: 2018-12-31

Gangwar M, Jha R, Goyal M, et al (2018)

Immunogenicity and protective efficacy of Recombinase A from Wolbachia endosymbiont of filarial nematode Brugia malayi (wBmRecA).

Vaccine pii:S0264-410X(18)31675-X [Epub ahead of print].

Lymphatic filariasis causes global morbidity. Wolbachia, an endo-symbiotic intracellular bacterium of the filarial nematode helps in their growth and development, regulates fecundity in female worms and contributes to the immunopathogenesis of the disease. However, genes and proteins of Wolbachia that may act as putative vaccine candidates are not known. In this study, we cloned recombinase-A protein of Wolbachia from Brugia malayi (wBmRecA) and carried out its detailed biochemical and immunological characterization. Bioinformatics analysis, circular dichroism and fluorescence spectral studies showed significant sequence and structural similarities between wBmRecA and RecA of other alpha-proteo- bacterial species. wBmRecA was ubiquitously expressed in all the three major life stages of B. malayi, including excretory-secretory products of the adult worm. In silico studies suggested immunogenic potential of wBmRecA, and mice immunized with wBmRecA exhibited elevated levels of immunoglobulins IgG1, IgG2a, IgG2b and IgG3 in their serum along with increased percentages of CD4+, CD8+ T cells and CD19+ B cells in their spleens. Notably, splenocytes from immunized mice showed increased m-RNA expression of T-bet, elevated proinflammatory cytokines IFN-γ and IL-12, while peritoneal MФs exhibited increased levels of iNOS, downregulated Arg-1 and secreted copious amounts of nitric oxide which contributed to severely impaired development of the infective larvae (Bm-L3). Interestingly, sera from immunized mice promoted significant cellular adherence and cytotoxicity against microfilariae and Bm-L3. Importantly, wBmRecA demonstrated strong immuno-reactivity with bancroftian sera from endemic normal individuals. These results suggest that wBmRecA is highly immunogenic, and should be explored further as a putative vaccine candidate against lymphatic filariasis.

RevDate: 2018-12-24

Mioduchowska M, Czyż MJ, Gołdyn B, et al (2018)

Detection of bacterial endosymbionts in freshwater crustaceans: the applicability of non-degenerate primers to amplify the bacterial 16S rRNA gene.

PeerJ, 6:e6039 pii:6039.

Bacterial endosymbionts of aquatic invertebrates remain poorly studied. This is at least partly due to a lack of suitable techniques and primers for their identification. We designed a pair of non-degenerate primers which enabled us to amplify a fragment of ca. 500 bp of the 16S rRNA gene from various known bacterial endosymbiont species. By using this approach, we identified four bacterial endosymbionts, two endoparasites and one uncultured bacterium in seven, taxonomically diverse, freshwater crustacean hosts from temporary waters across a wide geographical area. The overall efficiency of our new WOLBSL and WOLBSR primers for amplification of the bacterial 16S rRNA gene was 100%. However, if different bacterial species from one sample were amplified simultaneously, sequences were illegible, despite a good quality of PCR products. Therefore, we suggest using our primers at the first stage of bacterial endosymbiont identification. Subsequently, genus specific primers are recommended. Overall, in the era of next-generation sequencing our method can be used as a first simple and low-cost approach to identify potential microbial symbionts associated with freshwater crustaceans using simple Sanger sequencing. The potential to detected bacterial symbionts in various invertebrate hosts in such a way will facilitate studies on host-symbiont interactions and coevolution.

RevDate: 2018-12-15

Manzello DP, Matz MV, Enochs IC, et al (2018)

Role of host genetics and heat tolerant algal symbionts in sustaining populations of the endangered coral Orbicella faveolata in the Florida Keys with ocean warming.

Global change biology [Epub ahead of print].

Identifying which factors lead to coral bleaching resistance is a priority given the global decline of coral reefs with ocean warming. During the second year of back-to-back bleaching events in the Florida Keys in 2014 and 2015, we characterized key environmental and biological factors associated with bleaching resilience in the threatened reef-building coral Orbicella faveolata. Ten reefs (five inshore, five offshore, 179 corals total) were sampled during bleaching (September 2015) and recovery (May 2016). Corals were genotyped with 2bRAD and profiled for algal symbiont abundance and type. O. faveolata at the inshore sites, despite higher temperatures, demonstrated significantly higher bleaching resistance and better recovery compared to offshore. The thermotolerant Durusdinium trenchii (formerly Symbiondinium trenchii) was the dominant endosymbiont type region-wide during initial (78.0% of corals sampled) and final (77.2%) sampling; > 90% of the non-bleached corals were dominated by D. trenchii. 2bRAD host genotyping found no genetic structure among reefs, but inshore sites showed a high level of clonality. While none of the measured environmental parameters were correlated with bleaching, 71% of variation in bleaching resistance and 73% of variation in the proportion of D. trenchii was attributable to differences between genets, highlighting the leading role of genetics in shaping natural bleaching patterns. Notably, D. trenchii was rarely dominant in O. faveolata from the Florida Keys in previous studies, even during bleaching. The region-wide high abundance of D. trenchii was likely driven by repeated bleaching associated with the two warmest years on record for the Florida Keys (2014 and 2015). On inshore reefs in the upper Florida Keys, O. faveolata was most abundant, had the highest bleaching resistance, and contained the most corals dominated by D. trenchii, illustrating a causal link between heat tolerance and ecosystem resilience with global change. This article is protected by copyright. All rights reserved.

RevDate: 2018-12-14

Maddah FE, Nazir M, GM König (2017)

The Rare Amino Acid Building Block 3-(3-furyl)-Alanine in the Formation of Non-ribosomal Peptides.

Natural product communications, 12(1):147-150.

Microorganisms have made considerable contributions to the production of peptide secondary metabolites, many of them with therapeutic potential eg, the fungus-derived immunosuppressant cyclosporine A and the antibiotic daptomycin originating from Streptomyces. Most of the medically used peptides are the :product of non-ribosomal peptide synthetases (NRPS), incorporating apart from proteinogenic also unique, non-proteinogenic amino acids into the peptides. An extremely rare such amino acid is 3-(3-furyl)-alanine. So far, only few peptides have been found that contain this residue, including the rhizonins, bingchamide B and endolides. The producer of the rhizonins was proven to be the bacterial endosymbiont Burkholderia endofungorum inside the fungus Rhizopus microsporus. The microbial origin, chemistry and bioactivity of the 3-(3-furyl)-alanine containing peptides are the focus of this review.

RevDate: 2018-12-14

Baldini F, Rougé J, Kreppel K, et al (2018)

First report of natural Wolbachia infection in the malaria mosquito Anopheles arabiensis in Tanzania.

Parasites & vectors, 11(1):635 pii:10.1186/s13071-018-3249-y.

BACKGROUND: Natural infections of the endosymbiont bacteria Wolbachia have recently been discovered in populations of the malaria mosquito Anopheles gambiae (s.l.) in Burkina Faso and Mali, West Africa. This Anopheles specific strain wAnga limits the malaria parasite Plasmodium falciparum infections in the mosquito, thus it offers novel opportunities for malaria control.

RESULTS: We investigated Wolbachia presence in Anopheles arabiensis and Anopheles funestus, which are the two main malaria vectors in the Kilombero Valley, a malaria endemic region in south-eastern Tanzania. We found 3.1% (n = 65) and 7.5% (n = 147) wAnga infection prevalence in An. arabiensis in mosquitoes collected in 2014 and 2016, respectively, while no infection was detected in An. funestus (n = 41). Phylogenetic analysis suggests that at least two distinct strains of wAnga were detected, both belonging to Wolbachia supergroup A and B.

CONCLUSIONS: To our knowledge, this is the first confirmation of natural Wolbachia in malaria vectors in Tanzania, which opens novel questions on the ecological and genetic basis of its persistence and pathogen transmission in the vector hosts. Understanding the basis of interactions between Wolbachia, Anopheles mosquitoes and malaria parasites is crucial for investigation of its potential application as a biocontrol strategy to reduce malaria transmission, and assessment of how natural wAnga infections influence pathogen transmission in different ecological settings.

RevDate: 2018-12-14

Song S, Chen C, Yang M, et al (2018)

Diversity of Rickettsia species in border regions of northwestern China.

Parasites & vectors, 11(1):634 pii:10.1186/s13071-018-3233-6.

BACKGROUND: Rickettsia species belonging to the spotted fever group (SFG) cause infections in humans, domestic animals and wildlife. At least ten SFG Rickettsia species are known to occur in China. However, the distribution of rickettsiae in ticks and fleas in the border region of northwestern China have not been systematically studied to date.

RESULTS: A total of 982 ticks (Rhipicephalus turanicus, Dermacentor marginatus, D. nuttalli and Haemaphysalis punctata) and 5052 fleas (18 flea species from 14 species of wild mammals) were collected in ten and five counties, respectively, of Xinjiang Uygur Autonomous Region (northwestern China). Tick and flea species were identified according to morphological and molecular characteristics. Seven sets of primers for amplifying the 17-kDa antigen gene (17-kDa), citrate synthase gene (gltA), 16S rRNA gene (rrs), outer membrane protein A and B genes (ompA, ompB), surface cell antigen 1 gene (sca1) and PS120-protein encoding gene (gene D) were used to identify the species of rickettsiae. Nine Rickettsia species have been detected, seven of them in ticks: R. aeschlimannii, R. conorii, R. raoultii, Rickettsia sibirica, R. slovaca, R. massiliae and "Candidatus R. barbariae". In addition, R. bellii and two genotypes of a rickettsia endosymbiont (phylogenetically in an ancestral position to R. bellii) have been detected from flea pools.

CONCLUSIONS: This study provides molecular evidence for the occurrence of several SFG rickettsiae in Rhipicephalus turanicus, Dermacentor nuttalli and D. marginatus. Furthermore, R. bellii and two ancestral rickettsia endosymbionts are present in fleas infesting wild rodents in the border regions of northwestern China. These data extend our knowledge on the diversity of rickettsiae in Central Asia.

RevDate: 2018-12-12

Altamia MA, Shipway JR, Concepcion GP, et al (2018)

Thiosocius teredinicola gen. nov., sp. nov., a sulfur-oxidizing chemolithoautotrophic endosymbiont cultivated from the gills of the giant shipworm, Kuphus polythalamius.

International journal of systematic and evolutionary microbiology [Epub ahead of print].

A chemolithoautotrophic sulfur-oxidizing, diazotrophic, facultatively heterotrophic, endosymbiotic bacterium, designated as strain 2141T, was isolated from the gills of the giant shipworm Kuphus polythalamius (Teredinidae: Bivalvia). Based on its 16S rRNA sequence, the endosymbiont falls within a clade that includes the as-yet-uncultivated thioautotrophic symbionts of a marine ciliate and hydrothermal vent gastropods, uncultivated marine sediment bacteria, and a free-living sulfur-oxidizing bacterium ODIII6, all of which belong to the Gammaproteobacteria. The endosymbiont is Gram-negative, rod-shaped and has a single polar flagellum when grown in culture. This bacterium can be grown chemolithoautotrophically on a chemically defined medium supplemented with either hydrogen sulfide, thiosulfate, tetrathionate or elemental sulfur. The closed-circular genome has a DNA G+C content of 60.1 mol% and is 4.79 Mbp in size with a large nitrogenase cluster spanning nearly 40 kbp. The diazotrophic capability was confirmed by growing the strain on chemolithoautotrophic thiosulfate-based medium without a combined source of fixed nitrogen. The bacterium is also capable of heterotrophic growth on organic acids such as acetate and propionate. The pH, temperature and salinity optima for chemolithoautotrophic growth on thiosulfate were found to be 8.5, 34 °C and 0.2 M NaCl, respectively. To our knowledge, this is the first report of pure culture of a thioautotrophic animal symbiont. The type strain of Thiosocius teredinicola is PMS-2141T.STBD.0c.01aT (=DSM 108030T).

RevDate: 2018-12-11

Crowell RM, Nienow JA, A Bruce Cahoon (2018)

The complete chloroplast and mitochondrial genomes of the diatom Nitzschia palea (Bacillariophyceae) demonstrate high sequence similarity to the endosymbiont organelles of the dinotom Durinskia baltica.

Journal of phycology [Epub ahead of print].

Nitzschia palea is a common freshwater diatom used as a bioindicator because of its tolerance of polluted waterways. There is also evidence it may be the tertiary endosymbiont within the "dinotom" dinoflagellate Durinskia baltica. A putative strain of N. palea was collected from a pond on the University of Virginia's College at Wise campus and cultured. For initial identification, three markers were sequenced - nuclear 18S rDNA, the chloroplast 23S rDNA and rbcL. Morphological characteristics were determined using light and scanning electron microscopy; based on these observations the cells were identified as N. palea and named strain 'Wise'. DNA from N. palea was deep sequenced and the chloroplast and mitochondrial genomes assembled. Single gene phylogenies grouped N. palea - Wise within a clearly defined N. palea clade and showed it was most closely related to the strain 'SpainA3'. The chloroplast genome of N. palea is 119,447 bp with a quadripartite structure, 135 protein coding, 28 tRNA, and 3 rRNA genes. The mitochondrial genome is 37,754 bp with a single repeat region as found in other diatom chondriomes, 37 protein coding, 23 tRNA, and 2 rRNA genes. The chloroplast genomes of N. palea and D. baltica have identical gene content, synteny, and a 92.7% pairwise sequence similarity with most differences occurring in intergenic regions. The N. palea mitochondrial genome and D. baltica's endosymbiont mitochondrial genome also have identical gene content and order with a sequence similarity of 90.7%. Genome-based phylogenies demonstrated that D. baltica is more similar to N. palea than any other diatom sequence currently available. These data provide the genome sequences of two organelles for a widespread diatom and show they are very similar to those of D. baltica's endosymbiont. This article is protected by copyright. All rights reserved.

RevDate: 2018-12-11

Estes AM, Hearn DJ, Nadendla S, et al (2018)

Draft Genome Sequence of Enterobacter sp. Strain OLF, a Colonizer of Olive Flies.

Microbiology resource announcements, 7(9): pii:MRA01068-18.

Enterobacter sp. strain OLF colonizes laboratory-reared and wild individuals of the olive fruit fly Bactrocera oleae. The 5.07-kbp genome sequence of Enterobacter sp. strain OLF encodes metabolic pathways that allow the bacterium to partially supplement the diet of the olive fly when its dominant endosymbiont, Erwinia dacicola, is absent.

RevDate: 2018-12-11

Chung M, Teigen L, Libro S, et al (2018)

Multispecies Transcriptomics Data Set of Brugia malayi, Its Wolbachia Endosymbiont wBm, and Aedes aegypti across the B. malayi Life Cycle.

Microbiology resource announcements, 7(18): pii:MRA01306-18.

Here, we present a comprehensive transcriptomics data set of Brugia malayi, its Wolbachia endosymbiont wBm, and its vector host. This study samples from 16 stages across the entire B. malayi life cycle, including stage 1 through 4 larvae, adult males and females, embryos, immature microfilariae, and mature microfilariae.

RevDate: 2018-12-11

Estes AM, Hearn DJ, Nadendla S, et al (2018)

Draft Genome Sequence of Erwinia dacicola, a Dominant Endosymbiont of Olive Flies.

Microbiology resource announcements, 7(10): pii:MRA01067-18.

Erwinia dacicola is a dominant endosymbiont of the pestiferous olive fly. Its genome is similar in size and GC content to those of free-living Erwinia species, including the plant pathogen Erwinia amylovora. The E. dacicola genome encodes the metabolic capability to supplement and detoxify the olive fly's diet in larval and adult stages.

RevDate: 2018-12-06

Burmester EM, Breef-Pilz A, Lawrence NF, et al (2018)

The impact of autotrophic versus heterotrophic nutritional pathways on colony health and wound recovery in corals.

Ecology and evolution, 8(22):10805-10816 pii:ECE34531.

For animals that harbor photosynthetic symbionts within their tissues, such as corals, the different relative contributions of autotrophy versus heterotrophy to organismal energetic requirements have direct impacts on fitness. This is especially true for facultatively symbiotic corals, where the balance between host-caught and symbiont-produced energy can be altered substantially to meet the variable demands of a shifting environment. In this study, we utilized a temperate coral-algal system (the northern star coral, Astrangia poculata, and its photosynthetic endosymbiont, Symbiodinium psygmophilum) to explore the impacts of nutritional sourcing on the host's health and ability to regenerate experimentally excised polyps. For fed and starved colonies, wound healing and total colony tissue cover were differentially impacted by heterotrophy versus autotrophy. There was an additive impact of positive nutritional and symbiotic states on a coral's ability to initiate healing, but a greater influence of symbiont state on the recovery of lost tissue at the lesion site and complete polyp regeneration. On the other hand, regardless of symbiont state, fed corals maintained a higher overall colony tissue cover, which also enabled more active host behavior (polyp extension) and endosymbiont behavior (photosynthetic ability of Symbiondinium). Overall, we determined that the impact of nutritional state and symbiotic state varied between biological functions, suggesting a diversity in energetic sourcing for each of these processes.

RevDate: 2018-12-06

Lim SJ, Davis BG, Gill DE, et al (2018)

Taxonomic and functional heterogeneity of the gill microbiome in a symbiotic coastal mangrove lucinid species.

The ISME journal pii:10.1038/s41396-018-0318-3 [Epub ahead of print].

Lucinidae clams harbor gammaproteobacterial thioautotrophic gill endosymbionts that are environmentally acquired. Thioautotrophic lucinid symbionts are related to metabolically similar symbionts associated with diverse marine host taxa and fall into three distinct phylogenetic clades. Most studies on the lucinid-bacteria chemosymbiosis have been done with seagrass-dwelling hosts, whose symbionts belong to the largest phylogenetic clade. In this study, we examined the taxonomy and functional repertoire of bacterial endosymbionts at an unprecedented resolution from Phacoides pectinatus retrieved from mangrove-lined coastal sediments, which are underrepresented in chemosymbiosis studies. The P. pectinatus thioautotrophic endosymbiont expressed metabolic gene variants for thioautotrophy, respiration, and nitrogen assimilation distinct from previously characterized lucinid thioautotrophic symbionts and other marine symbionts. At least two other bacterial species with different metabolisms were also consistently identified in the P. pectinatus gill microbiome, including a Kistimonas-like species and a Spirochaeta-like species. Bacterial transcripts involved in adhesion, growth, and virulence and mixotrophy were highly expressed, as were host-related hemoglobin and lysozyme transcripts indicative of sulfide/oxygen/CO2 transport and bactericidal activity. This study suggests the potential roles of P. pectinatus and its gill microbiome species in mangrove sediment biogeochemistry and offers insights into host and microbe metabolisms in the habitat.

RevDate: 2018-12-03

McLean BJ, Dainty KR, Flores HA, et al (2018)

Differential suppression of persistent insect specific viruses in trans-infected wMel and wMelPop-CLA Aedes-derived mosquito lines.

Virology, 527:141-145 pii:S0042-6822(18)30359-3 [Epub ahead of print].

Wolbachia suppresses the replication of +ssRNA viruses such as dengue and Zika viruses in Aedes aegypti mosquitoes. However, the range of viruses affected by this endosymbiont is yet to be explored. Recently, novel insect-specific viruses (ISVs) have been described from numerous mosquito species and mosquito-derived cell lines. Cell-fusing agent virus (Flaviviridae) and Phasi Charoen-like virus (Bunyaviridae) persistently infect the Ae. aegypti cell line Aag2 which has been used for experimental studies with both the wMel and wMelPop-CLA strains. Wolbachia was found to restrict the replication of CFAV but not the PCLV infection in these lines. Furthermore, an additional Ae. albopictus cell line (RML-12) which contained either wMel or wMelPop-CLA was assessed. While no infectious +ssRNA or dsRNA viruses were detected, a PCLV infection was identified. These observations provide additional evidence to support that insect-specific, +ssRNA viruses can be suppressed in cell culture by Wolbachia but -ssRNA viruses may not.

RevDate: 2018-11-28

Cenci U, Sibbald SJ, Curtis BA, et al (2018)

Nuclear genome sequence of the plastid-lacking cryptomonad Goniomonas avonlea provides insights into the evolution of secondary plastids.

BMC biology, 16(1):137 pii:10.1186/s12915-018-0593-5.

BACKGROUND: The evolution of photosynthesis has been a major driver in eukaryotic diversification. Eukaryotes have acquired plastids (chloroplasts) either directly via the engulfment and integration of a photosynthetic cyanobacterium (primary endosymbiosis) or indirectly by engulfing a photosynthetic eukaryote (secondary or tertiary endosymbiosis). The timing and frequency of secondary endosymbiosis during eukaryotic evolution is currently unclear but may be resolved in part by studying cryptomonads, a group of single-celled eukaryotes comprised of both photosynthetic and non-photosynthetic species. While cryptomonads such as Guillardia theta harbor a red algal-derived plastid of secondary endosymbiotic origin, members of the sister group Goniomonadea lack plastids. Here, we present the genome of Goniomonas avonlea-the first for any goniomonad-to address whether Goniomonadea are ancestrally non-photosynthetic or whether they lost a plastid secondarily.

RESULTS: We sequenced the nuclear and mitochondrial genomes of Goniomonas avonlea and carried out a comparative analysis of Go. avonlea, Gu. theta, and other cryptomonads. The Go. avonlea genome assembly is ~ 92 Mbp in size, with 33,470 predicted protein-coding genes. Interestingly, some metabolic pathways (e.g., fatty acid biosynthesis) predicted to occur in the plastid and periplastidal compartment of Gu. theta appear to operate in the cytoplasm of Go. avonlea, suggesting that metabolic redundancies were generated during the course of secondary plastid integration. Other cytosolic pathways found in Go. avonlea are not found in Gu. theta, suggesting secondary loss in Gu. theta and other plastid-bearing cryptomonads. Phylogenetic analyses revealed no evidence for algal endosymbiont-derived genes in the Go. avonlea genome. Phylogenomic analyses point to a specific relationship between Cryptista (to which cryptomonads belong) and Archaeplastida.

CONCLUSION: We found no convincing genomic or phylogenomic evidence that Go. avonlea evolved from a secondary red algal plastid-bearing ancestor, consistent with goniomonads being ancestrally non-photosynthetic eukaryotes. The Go. avonlea genome sheds light on the physiology of heterotrophic cryptomonads and serves as an important reference point for studying the metabolic "rewiring" that took place during secondary plastid integration in the ancestor of modern-day Cryptophyceae.

RevDate: 2018-11-26

Hosseinzadeh S, Shams-Bakhsh M, Mann M, et al (2018)

Distribution and Variation of Bacterial Endosymbiont and "Candidatus Liberibacter asiaticus" Titer in the Huanglongbing Insect Vector, Diaphorina citri Kuwayama.

Microbial ecology pii:10.1007/s00248-018-1290-1 [Epub ahead of print].

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, is an economic insect pest in most citrus-growing regions and the vector of 'Candidatus Liberibacter asiaticus' (CLas), one of at least three known bacteria associated with Huanglongbing (HLB or citrus greening disease). D. citri harbors bacterial endosymbionts, including Wolbachia pipientis (strain Wolbachia wDi), 'Candidatus Carsonella ruddii,' and 'Candidatus Profftella armatura.' Many important functions of these bacteria can be inferred from their genome sequences, but their interactions with each other, CLas, and their D. citri host are poorly understood. In the present study, the titers of the endosymbionts in different tissues, in each sex, and in insects reared on healthy citrus (referred to as unexposed) and CLas-infected citrus (referred to as CLas-exposed) D. citri were investigated using real-time, quantitative PCR (qPCR) using two different quantitative approaches. Wolbachia and CLas were detected in all insect tissues. The titer of Wolbachia was higher in heads of CLas-exposed males as compared to unexposed males. In males and females, Wolbachia titer was highest in the Malpighian tubules. The highest titer of CLas was observed in the gut. Profftella and Carsonella titers were significantly reduced in the bacteriome of CLas-exposed males compared with that of unexposed males, but this effect was not observed in females. In ovaries of CLas-exposed females, the Profftella and Carsonella titers were increased as compared to non-exposed females. CLas appeared to influence the overall levels of the symbionts but did not drastically perturb the overall microbial community structure. In all the assessed tissues, CLas titer in males was significantly higher than that of females using absolute quantification. These data provide a better understanding of multi-trophic interactions regulating symbiont dynamics in the HLB pathosystem.

RevDate: 2018-11-27

Engl T, Michalkova V, Weiss BL, et al (2018)

Effect of antibiotic treatment and gamma-irradiation on cuticular hydrocarbon profiles and mate choice in tsetse flies (Glossina m. morsitans).

BMC microbiology, 18(Suppl 1):145 pii:10.1186/s12866-018-1292-7.

BACKGROUND: Symbiotic microbes represent a driving force of evolutionary innovation by conferring novel ecological traits to their hosts. Many insects are associated with microbial symbionts that contribute to their host's nutrition, digestion, detoxification, reproduction, immune homeostasis, and defense. In addition, recent studies suggest a microbial involvement in chemical communication and mating behavior, which can ultimately impact reproductive isolation and, hence, speciation. Here we investigated whether a disruption of the microbiota through antibiotic treatment or irradiation affects cuticular hydrocarbon profiles, and possibly mate choice behavior in the tsetse fly, Glossina morsitans morsitans. Four independent experiments that differentially knock down the multiple bacterial symbionts of tsetse flies were conducted by subjecting tsetse flies to ampicillin, tetracycline, or gamma-irradiation and analyzing their cuticular hydrocarbon profiles in comparison to untreated controls by gas chromatography - mass spectrometry. In two of the antibiotic experiments, flies were mass-reared, while individual rearing was done for the third experiment to avoid possible chemical cross-contamination between individual flies.

RESULTS: All three antibiotic experiments yielded significant effects of antibiotic treatment (particularly tetracycline) on cuticular hydrocarbon profiles in both female and male G. m. morsitans, while irradiation itself had no effect on the CHC profiles. Importantly, tetracycline treatment reduced relative amounts of 15,19,23-trimethyl-heptatriacontane, a known compound of the female contact sex pheromone, in two of the three experiments, suggesting a possible implication of microbiota disturbance on mate choice decisions. Concordantly, both female and male flies preferred non-treated over tetracycline-treated flies in direct choice assays.

CONCLUSIONS: While we cannot exclude the possibility that antibiotic treatment had a directly detrimental effect on fly vigor as we are unable to recolonize antibiotic treated flies with individual symbiont taxa, our results are consistent with an effect of the microbiota, particularly the obligate nutritional endosymbiont Wigglesworthia, on CHC profiles and mate choice behavior. These findings highlight the importance of considering host-microbiota interactions when studying chemical communication and mate choice in insects.

RevDate: 2018-11-28

Channumsin M, Ciosi M, Masiga D, et al (2018)

Sodalis glossinidius presence in wild tsetse is only associated with presence of trypanosomes in complex interactions with other tsetse-specific factors.

BMC microbiology, 18(Suppl 1):163 pii:10.1186/s12866-018-1285-6.

BACKGROUND: Susceptibility of tsetse flies (Glossina spp.) to trypanosomes of both humans and animals has been associated with the presence of the endosymbiont Sodalis glossinidius. However, intrinsic biological characteristics of the flies and environmental factors can influence the presence of both S. glossinidius and the parasites. It thus remains unclear whether it is the S. glossinidius or other attributes of the flies that explains the apparent association. The objective of this study was to test whether the presence of Trypanosoma vivax, T. congolense and T. brucei are related to the presence of S. glossinidius in tsetse flies when other factors are accounted for: geographic location, species of Glossina, sex or age of the host flies.

RESULTS: Flies (n = 1090) were trapped from four sites in the Shimba Hills and Nguruman regions in Kenya. Sex and species of tsetse (G. austeni, G. brevipalpis, G. longipennis and G. pallidipes) were determined based on external morphological characters and age was estimated by a wing fray score method. The presence of trypanosomes and S. glossinidius was detected using PCR targeting the internal transcribed spacer region 1 and the haemolysin gene, respectively. Sequencing was used to confirm species identification. Generalised Linear Models (GLMs) and Multiple Correspondence Analysis (MCA) were applied to investigate multivariable associations. The overall prevalence of trypanosomes was 42.1%, but GLMs revealed complex patterns of associations: the presence of S. glossinidius was associated with trypanosome presence but only in interactions with other factors and only in some species of trypanosomes. The strongest association was found for T. congolense, and no association was found for T. vivax. The MCA also suggested only a weak association between the presence of trypanosomes and S. glossinidius. Trypanosome-positive status showed strong associations with sex and age while S. glossinidius-positive status showed a strong association with geographic location and species of fly.

CONCLUSIONS: We suggest that previous conclusions about the presence of endosymbionts increasing probability of trypanosome presence in tsetse flies may have been confounded by other factors, such as community composition of the tsetse flies and the specific trypanosomes found in different regions.

RevDate: 2018-11-28

Griffith BC, Weiss BL, Aksoy E, et al (2018)

Analysis of the gut-specific microbiome from field-captured tsetse flies, and its potential relevance to host trypanosome vector competence.

BMC microbiology, 18(Suppl 1):146 pii:10.1186/s12866-018-1284-7.

BACKGROUND: The tsetse fly (Glossina sp.) midgut is colonized by maternally transmitted and environmentally acquired bacteria. Additionally, the midgut serves as a niche in which pathogenic African trypanosomes reside within infected flies. Tsetse's bacterial microbiota impacts many aspects of the fly's physiology. However, little is known about the structure of tsetse's midgut-associated bacterial communities as they relate to geographically distinct fly habitats in east Africa and their contributions to parasite infection outcomes. We utilized culture dependent and independent methods to characterize the taxonomic structure and density of bacterial communities that reside within the midgut of tsetse flies collected at geographically distinct locations in Kenya and Uganda.

RESULTS: Using culture dependent methods, we isolated 34 strains of bacteria from four different tsetse species (G. pallidipes, G. brevipalpis, G. fuscipes and G. fuscipleuris) captured at three distinct locations in Kenya. To increase the depth of this study, we deep sequenced midguts from individual uninfected and trypanosome infected G. pallidipes captured at two distinct locations in Kenya and one in Uganda. We found that tsetse's obligate endosymbiont, Wigglesworthia, was the most abundant bacterium present in the midgut of G. pallidipes, and the density of this bacterium remained largely consistent regardless of whether or not its tsetse host was infected with trypanosomes. These fly populations also housed the commensal symbiont Sodalis, which was found at significantly higher densities in trypanosome infected compared to uninfected flies. Finally, midguts of field-captured G. pallidipes were colonized with distinct, low density communities of environmentally acquired microbes that differed in taxonomic structure depending on parasite infection status and the geographic location from which the flies were collected.

CONCLUSIONS: The results of this study will enhance our understanding of the tripartite relationship between tsetse, its microbiota and trypanosome vector competence. This information may be useful for developing novel disease control strategies or enhancing the efficacy of those already in use.

RevDate: 2018-11-28

Zaidman-Rémy A, Vigneron A, Weiss BL, et al (2018)

What can a weevil teach a fly, and reciprocally? Interaction of host immune systems with endosymbionts in Glossina and Sitophilus.

BMC microbiology, 18(Suppl 1):150 pii:10.1186/s12866-018-1278-5.

The tsetse fly (Glossina genus) is the main vector of African trypanosomes, which are protozoan parasites that cause human and animal African trypanosomiases in Sub-Saharan Africa. In the frame of the IAEA/FAO program 'Enhancing Vector Refractoriness to Trypanosome Infection', in addition to the tsetse, the cereal weevil Sitophilus has been introduced as a comparative system with regards to immune interactions with endosymbionts. The cereal weevil is an agricultural pest that destroys a significant proportion of cereal stocks worldwide. Tsetse flies are associated with three symbiotic bacteria, the multifunctional obligate Wigglesworthia glossinidia, the facultative commensal Sodalis glossinidius and the parasitic Wolbachia. Cereal weevils house an obligatory nutritional symbiosis with the bacterium Sodalis pierantonius, and occasionally Wolbachia. Studying insect host-symbiont interactions is highly relevant both for understanding the evolution of symbiosis and for envisioning novel pest control strategies. In both insects, the long co-evolution between host and endosymbiont has led to a stringent integration of the host-bacteria partnership. These associations were facilitated by the development of specialized host traits, including symbiont-housing cells called bacteriocytes and specific immune features that enable both tolerance and control of the bacteria. In this review, we compare the tsetse and weevil model systems and compile the latest research findings regarding their biological and ecological similarities, how the immune system controls endosymbiont load and location, and how host-symbiont interactions impact developmental features including cuticle synthesis and immune system maturation. We focus mainly on the interactions between the obligate symbionts and their host's immune systems, a central theme in both model systems. Finally, we highlight how parallel studies on cereal weevils and tsetse flies led to mutual discoveries and stimulated research on each model, creating a pivotal example of scientific improvement through comparison between relatively distant models.

RevDate: 2018-11-23

Bi J, Zheng Y, Wang RF, et al (2018)

Wolbachia infection may improve learning and memory capacity of Drosophila by altering host gene expression through microRNA.

Insect biochemistry and molecular biology pii:S0965-1748(18)30294-7 [Epub ahead of print].

Wolbachia are endosymbiotic bacteria present in a wide range of invertebrates. Although their dramatic effects on host reproductive biology have been well studied, little is known about the effects of Wolbachia on the learning and memory capacity (LMC) of hosts, despite their distribution in the host nervous system, including brain. In this study, we found that Wolbachia infection significantly enhanced LMC in both Drosophila melanogaster and D. simulans. Expression of LMC-related genes was significantly increased in the head of D. melanogaster infected with the wMel strain, and among these genes, crebA was up-regulated the most. Knockdown of crebA in Wolbachia-infected flies significantly decreased LMC, while overexpression of crebA in Wolbachia-free flies significantly enhanced the LMC of flies. More importantly, a microRNA (miRNA), dme-miR-92b, was identified to be complementary to the 3'UTR of crebA. Wolbachia infection was correlated with reduced expression of dme-miR-92b in D. melanogaster, and dme-miR-92b negatively regulated crebA through binding to its 3'UTR region. Overexpression of dme-miR-92b in Wolbachia-infected flies by microinjection of agomirs caused a significant decrease in crebA expression and LMC, while inhibition of dme-miR-92b in Wolbachia-free flies by microinjection of antagomirs resulted in a significant increase in crebA expression and LMC. These results suggest that Wolbachia may improve LMC in Drosophila by altering host gene expression through a miRNA-target pathway. Our findings help better understand the host-endosymbiont interactions and, in particular, the impact of Wolbachia on cognitive processes in invertebrate hosts.

RevDate: 2018-11-22

Chen YL, Chen LJ, Chu CC, et al (2018)

TIC236 links the outer and inner membrane translocons of the chloroplast.

Nature pii:10.1038/s41586-018-0713-y [Epub ahead of print].

The two-membrane envelope is a defining feature of chloroplasts. Chloroplasts evolved from a Gram-negative cyanobacterial endosymbiont. During evolution, genes of the endosymbiont have been transferred to the host nuclear genome. Most chloroplast proteins are synthesized in the cytosol as higher-molecular-mass preproteins with an N-terminal transit peptide. Preproteins are transported into chloroplasts by the TOC and TIC (translocons at the outer- and inner-envelope membranes of chloroplasts, respectively) machineries1,2, but how TOC and TIC are assembled together is unknown. Here we report the identification of the TIC component TIC236; TIC236 is an integral inner-membrane protein that projects a 230-kDa domain into the intermembrane space, which binds directly to the outer-membrane channel TOC75. The knockout mutation of TIC236 is embryonically lethal. In TIC236-knockdown mutants, a smaller amount of the inner-membrane channel TIC20 was associated with TOC75; the amount of TOC-TIC supercomplexes was also reduced. This resulted in a reduced import rate into the stroma, though outer-membrane protein insertion was unaffected. The size and the essential nature of TIC236 indicate that-unlike in mitochondria, in which the outer- and inner-membrane translocons exist as separate complexes and a supercomplex is only transiently assembled during preprotein translocation3,4-a long and stable protein bridge in the intermembrane space is required for protein translocation into chloroplasts. Furthermore, TIC236 and TOC75 are homologues of bacterial inner-membrane TamB5 and outer-membrane BamA, respectively. Our evolutionary analyses show that, similar to TOC75, TIC236 is preserved only in plants and has co-evolved with TOC75 throughout the plant lineage. This suggests that the backbone of the chloroplast protein-import machinery evolved from the bacterial TamB-BamA protein-secretion system.

RevDate: 2018-11-23

Brown AMV, Wasala SK, Howe DK, et al (2018)

Comparative Genomics of Wolbachia-Cardinium Dual Endosymbiosis in a Plant-Parasitic Nematode.

Frontiers in microbiology, 9:2482.

Wolbachia and Cardinium are among the most important and widespread of all endosymbionts, occurring in nematodes and more than half of insect and arachnid species, sometimes as coinfections. These symbionts are of significant interest as potential biocontrol agents due to their abilities to cause major effects on host biology and reproduction through cytoplasmic incompatibility, sex ratio distortion, or obligate mutualism. The ecological and metabolic effects of coinfections are not well understood. This study examined a Wolbachia-Cardinium coinfection in the plant-parasitic nematode (PPN), Pratylenchus penetrans, producing the first detailed study of such a coinfection using fluorescence in situ hybridization (FISH), polymerase chain reaction (PCR), and comparative genomic analysis. Results from FISH and single-nematode PCR showed 123/127 individuals in a focal population carried Cardinium (denoted strain cPpe), and 48% were coinfected with Wolbachia strain wPpe. Both endosymbionts showed dispersed tissue distribution with highest densities in the anterior intestinal walls and gonads. Phylogenomic analyses confirmed an early place of cPpe and long distance from a sister strain in another PPN, Heterodera glycines, supporting a long history of both Cardinium and Wolbachia in PPNs. The genome of cPpe was 1.36 Mbp with 35.8% GC content, 1,131 predicted genes, 41% having no known function, and missing biotin and lipoate synthetic capacity and a plasmid present in other strains, despite having a slightly larger genome compared to other sequenced Cardinium. The larger genome revealed expansions of gene families likely involved in host-cellular interactions. More than 2% of the genes of cPpe and wPpe were identified as candidate horizontally transferred genes, with some of these from eukaryotes, including nematodes. A model of the possible Wolbachia-Cardinium interaction is proposed with possible complementation in function for pathways such as methionine and fatty acid biosynthesis and biotin transport.

RevDate: 2018-11-20

Schneider DI, Ehrman L, Engl T, et al (2018)

Symbiont-Driven Male Mating Success in the Neotropical Drosophila paulistorum Superspecies.

Behavior genetics pii:10.1007/s10519-018-9937-8 [Epub ahead of print].

Microbial symbionts are ubiquitous associates of living organisms but their role in mediating reproductive isolation (RI) remains controversial. We addressed this knowledge gap by employing the Drosophila paulistorum-Wolbachia model system. Semispecies in the D. paulistorum species complex exhibit strong RI between each other and knockdown of obligate mutualistic Wolbachia bacteria in female D. paulistorum flies triggers loss of assortative mating behavior against males carrying incompatible Wolbachia strains. Here we set out to determine whether de novo RI can be introduced by Wolbachia-knockdown in D. paulistorum males. We show that Wolbachia-knockdown D. paulistorum males (i) are rejected as mates by wild type females, (ii) express altered sexual pheromone profiles, and (iii) are devoid of the endosymbiont in pheromone producing cells. Our findings suggest that changes in Wolbachia titer and tissue tropism can induce de novo premating isolation by directly or indirectly modulating sexual behavior of their native D. paulistorum hosts.

RevDate: 2018-11-18

Herran B, Cerveau N, Houdelet C, et al (2018)

IGFBP-rP1, a strongly conserved member of the androgenic hormone signalling pathway in Isopoda.

General and comparative endocrinology pii:S0016-6480(18)30278-8 [Epub ahead of print].

The first protein which has been described to interact with the malacostracan Androgenic Gland Hormone (AGH) is a binding protein called IGFBP-rP1. It has been identified and studied in several species of decapods, in which its interaction with the masculinizing hormone and its expression patterns have been established in several ways. However, this protein remains uncharacterised to date in the other malacostracan orders, like Amphipoda and Isopoda, although they were historically the first ones in which the androgenic gland and the corresponding hormone were respectively described. In this article, we identified the IGFBP-rP1 of isopods and established its implication in the pathway of the AGH with a silencing approach in the model species Armadillidium vulgare. We also showed that this gene is expressed in all the tissues of males and females, with a similar pattern in animals infected with Wolbachia, a feminizing endosymbiont of several isopod species. The expression pattern did not differ during the development of uninfected and infected animals either. We finally studied the evolution of the IGFBP-rP1 in 68 isopod species, looking for conserved motifs and evidence of natural selection. Altogether, our results showed that this gene is constitutively expressed and strongly conserved in isopods, in which it likely constitutes a key element of the insulin/IGF signalling pathway. However, we also illustrated that IGFBP-rP1 is not sufficient on its own to explain the different developmental paths taken by the males and the females or feminized genetic males.

RevDate: 2018-11-21

Hines HN, Onsbring H, Ettema TJG, et al (2018)

Molecular Investigation of the Ciliate Spirostomum semivirescens, with First Transcriptome and New Geographical Records.

Protist, 169(6):875-886 pii:S1434-4610(18)30084-1 [Epub ahead of print].

The ciliate Spirostomum semivirescens is a large freshwater protist densely packed with endosymbiotic algae and capable of building a protective coating from surrounding particles. The species has been rarely recorded and it lacks any molecular investigations. We obtained such data from S. semivirescens isolated in the UK and Sweden. Using single-cell RNA sequencing of isolates from both countries, the transcriptome of S. semivirescens was generated. A phylogenetic analysis identified S. semivirescens as a close relative to S. minus. Additionally, rRNA sequence analysis of the green algal endosymbiont revealed that it is closely related to Chlorella vulgaris. Along with the molecular species identification, an analysis of the ciliates' stop codons was carried out, which revealed a relationship where TGA stop codon frequency decreased with increasing gene expression levels. The observed codon bias suggests that S. semivirescens could be in an early stage of reassigning the TGA stop codon. Analysis of the transcriptome indicates that S. semivirescens potentially uses rhodoquinol-dependent fumarate reduction to respire in the oxygen-depleted habitats where it lives. The data also shows that despite large geographical distances (over 1,600km) between the sampling sites investigated, a morphologically-identical species can share an exact molecular signature, suggesting that some ciliate species, even those over 1mm in size, could have a global biogeographical distribution.

RevDate: 2018-11-14

Mohanty I, Rath A, Swain SP, et al (2018)

Wolbachia Population in Vectors and Non-vectors: A Sustainable Approach Towards Dengue Control.

Current microbiology pii:10.1007/s00284-018-1596-8 [Epub ahead of print].

Wolbachia is gram negative obligate endosymbiont known for reproductive manipulation in the host. It is important to study the presence of natural Wolbachia in mosquitoes which can later help in understanding the effect of transfected strain on indigenous strain. With this view, the present study is undertaken to focus on the prevalence, diversity, infection frequencies, phylogeny and density of indigenous Wolbachia strains in wild mosquito species of Odisha. Our study confirms Wolbachia presence in Ae. albopictus, Cx. quinquefasciatus, Cx. vishnui, Cx. gelidus, Ar. subalbatus, Mn. uniformis, and Mn. indiana. Wolbachia in the above mosquitoes were separated into two supergroups (A and B). Ae. albopictus, the major vector of dengue and chikungungunya had both super-infection and mono-infection. The ovaries of Ae. albopictus were highest in density of Wolbachia as compared to midguts or salivary glands. wAlBA and wAlbB density were variable in mosquitoes of F1 generation for both the sex and at different age. We also found that Wolbachia super-infection in females tends to increase whereas wAlbA density reduced completely as compared to wAlbB in males when they grew old. Giemsa stained squashed ovaries revealed pink pleomorphic Wolbachia cells with different shapes and forms. This study is unique in its kind covering the major aspects of the endosymbiont Wolbachia and focusing on its potential as a biocontrol agent in arboviral outbreaks. Knowledge on potential of the indigenous strain and interactions between Wolbachia and viruses can be utilized further to reduce the global burden of vector borne diseases.

RevDate: 2018-11-16

Campbell MA, Łukasik P, Meyer MC, et al (2018)

Changes in Endosymbiont Complexity Drive Host-Level Compensatory Adaptations in Cicadas.

mBio, 9(6): pii:mBio.02104-18.

For insects that depend on one or more bacterial endosymbionts for survival, it is critical that these bacteria are faithfully transmitted between insect generations. Cicadas harbor two essential bacterial endosymbionts, "Candidatus Sulcia muelleri" and "Candidatus Hodgkinia cicadicola." In some cicada species, Hodgkinia has fragmented into multiple distinct but interdependent cellular and genomic lineages that can differ in abundance by more than two orders of magnitude. This complexity presents a potential problem for the host cicada, because low-abundance but essential Hodgkinia lineages risk being lost during the symbiont transmission bottleneck from mother to egg. Here we show that all cicada eggs seem to receive the full complement of Hodgkinia lineages, and that in cicadas with more complex Hodgkinia this outcome is achieved by increasing the number of Hodgkinia cells transmitted by up to 6-fold. We further show that cicada species with varying Hodgkinia complexity do not visibly alter their transmission mechanism at the resolution of cell biological structures. Together these data suggest that a major cicada adaptation to changes in endosymbiont complexity is an increase in the number of Hodgkinia cells transmitted to each egg. We hypothesize that the requirement to increase the symbiont titer is one of the costs associated with Hodgkinia fragmentation.IMPORTANCE Sap-feeding insects critically rely on one or more bacteria or fungi to provide essential nutrients that are not available at sufficient levels in their diets. These microbes are passed between insect generations when the mother places a small packet of microbes into each of her eggs before it is laid. We have previously described an unusual lineage fragmentation process in a nutritional endosymbiotic bacterium of cicadas called Hodgkinia In some cicadas, a single Hodgkinia lineage has split into numerous related lineages, each performing a subset of original function and therefore each required for normal host function. Here we test how this splitting process affects symbiont transmission to eggs. We find that cicadas dramatically increase the titer of Hodgkinia cells passed to each egg in response to lineage fragmentation, and we hypothesize that this increase in bacterial cell count is one of the major costs associated with endosymbiont fragmentation.

RevDate: 2018-11-14

Lv N, Wang L, Sang W, et al (2018)

Effects of Endosymbiont Disruption on the Nutritional Dynamics of the Pea Aphid Acyrthosiphon pisum.

Insects, 9(4): pii:insects9040161.

Pea aphid (Acyrthosiphon pisum) is a worldwide pest that feeds exclusively on the phloem sap of numerous host plants. It harbours a well-known primary endosymbiont Buchneraaphidicola that helps to overcome the nutritional deficiency of a plant-based diet. However, how the Buchnera contributes to the nutritional and energy metabolism of its aphid host is unclear to date. In the current study, the function of Buchnera in relation to nutritional synthesis of pea aphid was investigated by disrupting the primary endosymbiont with an antibiotic rifampicin. Our findings revealed that the disruption of Buchnera led to infertility and higher loss in body mass of aphid hosts. Body length and width were also decreased significantly compared to healthy aphids. The detection of nutrition indicated that the quantity of proteins, soluble sugars, and glycogen in aposymbiotic pea aphids increased slowly with the growth of the aphid host. In comparison, the quantities of all the nutritional factors were significantly lower than those of symbiotic pea aphids, while the quantity of total lipid and neutral fat in aposymbiotic pea aphids were distinctly higher than those of symbiotic ones. Thus, we concluded that the significant reduction of the total amount of proteins, soluble sugars, and glycogen and the significant increase of neutral fats in aposymbiotic pea aphids were due to the disruption of Buchnera, which confirmed that the function of Buchnera is irreplaceable in the pea aphid.

RevDate: 2018-11-12

Flores-Félix JD, Sánchez-Juanes F, García-Fraile P, et al (2018)

Phaseolus vulgaris is nodulated by the symbiovar viciae of several genospecies of Rhizobium laguerreae complex in a Spanish region where Lens culinaris is the traditionally cultivated legume.

Systematic and applied microbiology pii:S0723-2020(18)30367-9 [Epub ahead of print].

Phaseolus vulgaris and Lens culinaris are two legumes with different distribution centers that were introduced in Spain at different times, but in some regions L. culinaris has been traditionally cultivated and P. vulgaris did not. Here we analysed the rhizobia isolated from nodules of these two legumes in one of these regions. MALDI-TOF MS analysis showed that all isolated strains matched with Rhizobium laguerreae and the phylogenetic analysis of rrs, atpD and recA genes confirmed these results. The phylogenetic analysis of these core genes allowed the differentiation of several groups within R. laguerreae and unexpectedly, strains with housekeeping genes identical to that of the type strain of R. laguerreae presented some differences in the rrs gene. In some strains this gene contains an intervening sequence (IVS) identical to that found in Rhizobium strains nodulating several legumes in different geographical locations. The atpD, recA and nodC genes of all isolated strains clustered with those of strains nodulating L. culinaris in its distribution centers, but not with those nodulating P. vulgaris in theirs. Therefore, all these strains belong to the symbiovar viciae, including those isolated from P. vulgaris, which in the studied region established effective symbiosis with the common endosymbiont of L. culinaris, instead to with its common endosymbiont, the symbiovar phaseoli. These results are particularly interesting for biogeography studies, because they showed that, due its high promiscuity degree, P. vulgaris is able to establish symbiosis with local symbiovars well established in the soil after centuries of cultivation with other legumes.

RevDate: 2018-11-10

Schuler H, Lopez JA, Doellman MM, et al (2019)

Target-Enriched Endosymbiont Sequencing (TEEseq): A New High-Throughput Sequencing Approach Applied to the Comprehensive Characterization of Endosymbionts.

Methods in molecular biology (Clifton, N.J.), 1858:195-212.

Intracellular bacteria are ubiquitous in the insect world, with perhaps the best-studied example being the alphaproteobacterium, Wolbachia. Like most endosymbionts, Wolbachia cannot be cultivated outside of its host cells, hindering traditional microbial characterization techniques. Furthermore, multiple Wolbachia strains can be present within a single host, and certain strains can be present in densities below the detection limit of current methods. To date, Wolbachia has most commonly been studied using polymerase chain reaction (PCR) amplification and Sanger DNA sequencing by targeting specific genes in the bacterium's genome. PCR amplification and Sanger sequencing of multiple Wolbachia strains requires analysis of individually cloned sequences, which is resource and labor intensive. To help mitigate these difficulties, we present a modified double digest restriction site associated DNA sequencing (ddRADseq) approach to target and sequence in parallel multiple genes by adding restriction enzyme recognition sites to gene-specific PCR primers. Adopting this strategy allows us to uniquely tag and sequence amplicons from multiple hosts simultaneously on an Illumina MiSeq platform. Our approach represents an efficient and cost-effective method to characterize multiple target genes in population surveys.

RevDate: 2018-11-14

Colella S, Parisot N, Simonet P, et al (2018)

Bacteriocyte Reprogramming to Cope With Nutritional Stress in a Phloem Sap Feeding Hemipteran, the Pea Aphid Acyrthosiphon pisum.

Frontiers in physiology, 9:1498.

Nutritional symbioses play a central role in the ability of insects to thrive on unbalanced diets and in ensuring their evolutionary success. A genomic model for nutritional symbiosis comprises the hemipteran Acyrthosiphon pisum, and the gamma-3-proteobacterium, Buchnera aphidicola, with genomes encoding highly integrated metabolic pathways. A. pisum feeds exclusively on plant phloem sap, a nutritionally unbalanced diet highly variable in composition, thus raising the question of how this symbiotic system responds to nutritional stress. We addressed this by combining transcriptomic, phenotypic and life history trait analyses to determine the organismal impact of deprivation of tyrosine and phenylalanine. These two aromatic amino acids are essential for aphid development, are synthesized in a metabolic pathway for which the aphid host and the endosymbiont are interdependent, and their concentration can be highly variable in plant phloem sap. We found that this nutritional challenge does not have major phenotypic effects on the pea aphid, except for a limited weight reduction and a 2-day delay in onset of nymph laying. Transcriptomic analyses through aphid development showed a prominent response in bacteriocytes (the core symbiotic tissue which houses the symbionts), but not in gut, thus highlighting the role of bacteriocytes as major modulators of this homeostasis. This response does not involve a direct regulation of tyrosine and phenylalanine biosynthetic pathway and transporter genes. Instead, we observed an extensive transcriptional reprogramming of the bacteriocyte with a rapid down-regulation of genes encoding sugar transporters and genes required for sugar metabolism. Consistently, we observed continued overexpression of the A. pisum homolog of RRAD, a small GTPase implicated in repressing aerobic glycolysis. In addition, we found increased transcription of genes involved in proliferation, cell size control and signaling. We experimentally confirmed the significance of these gene expression changes detecting an increase in bacteriocyte number and cell size in vivo under tyrosine and phenylalanine depletion. Our results support a central role of bacteriocytes in the aphid response to amino acid deprivation: their transcriptional and cellular responses fine-tune host physiology providing the host insect with an effective way to cope with the challenges posed by the variability in composition of phloem sap.

RevDate: 2018-11-14

Cissoko M, Hocher V, Gherbi H, et al (2018)

Actinorhizal Signaling Molecules: Frankia Root Hair Deforming Factor Shares Properties With NIN Inducing Factor.

Frontiers in plant science, 9:1494.

Actinorhizal plants are able to establish a symbiotic relationship with Frankia bacteria leading to the formation of root nodules. The symbiotic interaction starts with the exchange of symbiotic signals in the soil between the plant and the bacteria. This molecular dialog involves signaling molecules that are responsible for the specific recognition of the plant host and its endosymbiont. Here we studied two factors potentially involved in signaling between Frankia casuarinae and its actinorhizal host Casuarina glauca: (1) the Root Hair Deforming Factor (CgRHDF) detected using a test based on the characteristic deformation of C. glauca root hairs inoculated with F. casuarinae and (2) a NIN activating factor (CgNINA) which is able to activate the expression of CgNIN, a symbiotic gene expressed during preinfection stages of root hair development. We showed that CgRHDF and CgNINA corresponded to small thermoresistant molecules. Both factors were also hydrophilic and resistant to a chitinase digestion indicating structural differences from rhizobial Nod factors (NFs) or mycorrhizal Myc-LCOs. We also investigated the presence of CgNINA and CgRHDF in 16 Frankia strains representative of Frankia diversity. High levels of root hair deformation (RHD) and activation of ProCgNIN were detected for Casuarina-infective strains from clade Ic and closely related strains from clade Ia unable to nodulate C. glauca. Lower levels were present for distantly related strains belonging to clade III. No CgRHDF or CgNINA could be detected for Frankia coriariae (Clade II) or for uninfective strains from clade IV.

RevDate: 2018-11-06

Hagen R, Verhoeve VI, Gillespie JJ, et al (2018)

Conjugative transposons and their cargo genes vary across natural populations of Rickettsia buchneri infecting the tick Ixodes scapularis.

Genome biology and evolution pii:5162483 [Epub ahead of print].

Rickettsia buchneri (formerly Rickettsia endosymbiont of Ixodes scapularis, or REIS) is an obligate intracellular endosymbiont of the black-legged tick, the primary vector of Lyme disease in North America. It is noteworthy among the rickettsiae for its relatively large genome (1.8 Mb) and extraordinary proliferation of mobile genetic elements (MGEs), which comprise nearly 35% of its genome. Previous analysis of the R. buchneri genome identified several integrative conjugative elements named RAGEs (Rickettsiales amplified genomic elements); the composition of these RAGEs suggests that continued genomic invasions by MGEs facilitated the proliferation of rickettsial genes related to an intracellular lifestyle. In this study, we compare the genomic diversity at RAGE loci among sequenced rickettsiae that infect three related Ixodes spp., including two strains of R. buchneri and Rickettsia endosymbiont of Ixodes pacificus strain Humboldt, as well as a closely-related species R. tamurae infecting Amblyomma testudinarium ticks. We further develop a novel multiplex droplet digital PCR assay and use it to quantify copy number ratios of chromosomal R. buchneri RAGE-A and RAGE-B to the single-copy gene gltA within natural populations of I. scapularis. Our results reveal substantial diversity among R. buchneri at these loci, both within individual ticks as well as in the I. scapularis population at large, demonstrating that genomic rearrangement of MGEs is an active process in these intracellular bacteria.

RevDate: 2018-11-14

Estes AM, Hearn DJ, Agrawal S, et al (2018)

Comparative genomics of the Erwinia and Enterobacter olive fly endosymbionts.

Scientific reports, 8(1):15936 pii:10.1038/s41598-018-33809-w.

The pestivorous tephritid olive fly has long been known as a frequent host of the obligately host-associated bacterial endosymbiont, Erwinia dacicola, as well as other facultative endosymbionts. The genomes of Erwinia dacicola and Enterobacter sp. OLF, isolated from a California olive fly, encode the ability to supplement amino acids and vitamins missing from the olive fruit on which the larvae feed. The Enterobacter sp. OLF genome encodes both uricase and ureases, and the Er. dacicola genome encodes an allantoate transport pathway, suggesting that bird feces or recycling the fly's waste products may be important sources of nitrogen. No homologs to known nitrogenases were identified in either bacterial genome, despite suggestions of their presence from experiments with antibiotic-treated flies. Comparisons between the olive fly endosymbionts and their free-living relatives revealed similar GC composition and genome size. The Er. dacicola genome has fewer genes for amino acid metabolism, cell motility, and carbohydrate transport and metabolism than free-living Erwinia spp. while having more genes for cell division, nucleotide metabolism and replication as well as mobile elements. A 6,696 bp potential lateral gene transfer composed primarily of amino acid synthesis and transport genes was identified that is also observed in Pseudomonas savastanoii pv savastanoii, the causative agent of olive knot disease.

RevDate: 2018-11-29

Mehta AP, Supekova L, Chen JH, et al (2018)

Engineering yeast endosymbionts as a step toward the evolution of mitochondria.

Proceedings of the National Academy of Sciences of the United States of America, 115(46):11796-11801.

It has been hypothesized that mitochondria evolved from a bacterial ancestor that initially became established in an archaeal host cell as an endosymbiont. Here we model this first stage of mitochondrial evolution by engineering endosymbiosis between Escherichia coli and Saccharomyces cerevisiae An ADP/ATP translocase-expressing E. coli provided ATP to a respiration-deficient cox2 yeast mutant and enabled growth of a yeast-E. coli chimera on a nonfermentable carbon source. In a reciprocal fashion, yeast provided thiamin to an endosymbiotic E. coli thiamin auxotroph. Expression of several SNARE-like proteins in E. coli was also required, likely to block lysosomal degradation of intracellular bacteria. This chimeric system was stable for more than 40 doublings, and GFP-expressing E. coli endosymbionts could be observed in the yeast by fluorescence microscopy and X-ray tomography. This readily manipulated system should allow experimental delineation of host-endosymbiont adaptations that occurred during evolution of the current, highly reduced mitochondrial genome.

RevDate: 2018-11-22

Paris Z, JD Alfonzo (2018)

How the intracellular partitioning of tRNA and tRNA modification enzymes affects mitochondrial function.

IUBMB life, 70(12):1207-1213.

Organisms have evolved different strategies to seclude certain molecules to specific locations of the cell. This is most pronounced in eukaryotes with their extensive intracellular membrane systems. Intracellular compartmentalization is particularly critical in genome containing organelles, which because of their bacterial evolutionary ancestry still maintain protein-synthesis machinery that resembles more their evolutionary origin than the extant eukaryotic cell they once joined as an endosymbiont. Despite this, it is clear that genome-containing organelles such as the mitochondria are not in isolation and many molecules make it across the mitochondrial membranes from the cytoplasm. In this realm the import of tRNAs and the enzymes that modify them prove most consequential. In this review, we discuss two recent examples of how modifications typically found in cytoplasmic tRNAs affect mitochondrial translation in organisms that forcibly import all their tRNAs from the cytoplasm. In our view, the combination of tRNA import and the compartmentalization of modification enzymes must have played a critical role in the evolution of the organelle. © 2018 IUBMB Life, 70(12):1207-1213, 2018.

RevDate: 2018-11-20

Chan LL, Mak JW, Ambu S, et al (2018)

Identification and ultrastructural characterization of Acanthamoeba bacterial endocytobionts belonging to the Alphaproteobacteria class.

PloS one, 13(10):e0204732 pii:PONE-D-17-35066.

The detection and identification of two endocytobiotic bacterial strains, one affiliated to the "Candidatus Caedibacter acanthamoebae"/"Ca. Paracaedimonas acanthamoeba", and another to the endosymbiont of Acanthamoeba UWC8 and "Ca. Jidaibacter acanthamoeba" are described. For endocytobiont screening, we developed a PCR method with a set of broad-range bacterial 16S rRNA primers to substitute the commonly used but technically demanding fluorescent in situ hybridization technique. Our PCR test alone without sequencing failed to discriminate the endocytobiont-containing and endocytobiont-free Acanthamoeba sp. due to the presence of mismatched primers to host mitochondrial DNA. We highlighted the need to perform bacterial primer checking against the Acanthamoeba genome to avoid false positive detection in PCR. Although the genetic aspect of "Ca. Caedibacter acanthamoebae"/"Ca. Paracaedimonas acanthamoeba" and the endosymbiont of Acanthamoeba UWC8/"Ca. Jidaibacter acanthamoeba" are well studied, knowledge pertaining to their morphologies are quite vague. Hence, we used transmission electron microscopy to examine our endocytobionts which are affiliated to previously described intracellular bacteria of Acanthamoeba sp. We used good-quality TEM images for the localization and the fate of the current endocytobionts inside different life stages of the hosts. Furthermore, to the best of our knowledge, our TEM findings are the first to provide morphological evidence for the clearance of defective Acanthamoeba endocytobionts via an autophagic-like process.

RevDate: 2018-11-14

Cenci U, Qiu H, Pillonel T, et al (2018)

Host-pathogen biotic interactions shaped vitamin K metabolism in Archaeplastida.

Scientific reports, 8(1):15243 pii:10.1038/s41598-018-33663-w.

Menaquinone (vitamin K2) shuttles electrons between membrane-bound respiratory complexes under microaerophilic conditions. In photosynthetic eukaryotes and cyanobacteria, phylloquinone (vitamin K1) participates in photosystem I function. Here we elucidate the evolutionary history of vitamin K metabolism in algae and plants. We show that Chlamydiales intracellular pathogens made major genetic contributions to the synthesis of the naphthoyl ring core and the isoprenoid side-chain of these quinones. Production of the core in extremophilic red algae is under control of a menaquinone (Men) gene cluster consisting of 7 genes that putatively originated via lateral gene transfer (LGT) from a chlamydial donor to the plastid genome. In other green and red algae, functionally related nuclear genes also originated via LGT from a non-cyanobacterial, albeit unidentified source. In addition, we show that 3-4 of the 9 required steps for synthesis of the isoprenoid side chains are under control of genes of chlamydial origin. These results are discussed in the light of the hypoxic response experienced by the cyanobacterial endosymbiont when it gained access to the eukaryotic cytosol.

RevDate: 2018-11-14

Santos-Garcia D, Juravel K, Freilich S, et al (2018)

To B or Not to B: Comparative Genomics Suggests Arsenophonus as a Source of B Vitamins in Whiteflies.

Frontiers in microbiology, 9:2254.

Insect lineages feeding on nutritionally restricted diets such as phloem sap, xylem sap, or blood, were able to diversify by acquiring bacterial species that complement lacking nutrients. These bacteria, considered obligate/primary endosymbionts, share a long evolutionary history with their hosts. In some cases, however, these endosymbionts are not able to fulfill all of their host's nutritional requirements, driving the acquisition of additional symbiotic species. Phloem-feeding members of the insect family Aleyrodidae (whiteflies) established an obligate relationship with Candidatus Portiera aleyrodidarum, which provides its hots with essential amino acids and carotenoids. In addition, many whitefly species harbor additional endosymbionts which may potentially further supplement their host's diet. To test this hypothesis, genomes of several endosymbionts of the whiteflies Aleurodicus dispersus, Aleurodicus floccissimus and Trialeurodes vaporariorum were analyzed. In addition to Portiera, all three species were found to harbor one Arsenophonus and one Wolbachia endosymbiont. A comparative analysis of Arsenophonus genomes revealed that although all three are capable of synthesizing B vitamins and cofactors, such as pyridoxal, riboflavin, or folate, their genomes and phylogenetic relationship vary greatly. Arsenophonus of A. floccissimus and T. vaporariorum belong to the same clade, and display characteristics of facultative endosymbionts, such as large genomes (3 Mb) with thousands of genes and pseudogenes, intermediate GC content, and mobile genetic elements. In contrast, Arsenophonus of A. dispersus belongs to a different lineage and displays the characteristics of a primary endosymbiont-a reduced genome (670 kb) with ~400 genes, 32% GC content, and no mobile genetic elements. However, the presence of 274 pseudogenes suggests that this symbiotic association is more recent than other reported primary endosymbionts of hemipterans. The gene repertoire of Arsenophonus of A. dispersus is completely integrated in the symbiotic consortia, and the biosynthesis of most vitamins occurs in shared pathways with its host. In addition, Wolbachia endosymbionts have also retained the ability to produce riboflavin, flavin adenine dinucleotide, and folate, and may make a nutritional contribution. Taken together, our results show that Arsenophonus hold a pivotal place in whitefly nutrition by their ability to produce B vitamins.

RevDate: 2018-10-12

Kikuchi S, Asakura Y, Imai M, et al (2018)

A Ycf2-FtsHi heteromeric AAA-ATPase complex is required for chloroplast protein import.

The Plant cell pii:tpc.18.00357 [Epub ahead of print].

Chloroplasts import thousands of nucleus-encoded preproteins synthesized in the cytosol through the TOC and TIC translocons on the outer and inner envelope membranes, respectively. Preprotein translocation across the inner membrane requires ATP; however, the import motor has remained unclear. Here, we report that a 2-MDa heteromeric AAA-ATPase complex associates with the TIC complex and functions as the import motor, directly interacting with various translocating preproteins. This 2-MDa complex consists of a protein encoded by the previously enigmatic chloroplast gene Ycf2 and five related nuclear-encoded FtsH-like proteins, namely FtsHi1, FtsHi2, FtsHi4, FtsHi5, and FtsH12. These components are each essential for plant viability and retain the AAA-type ATPase domain, but only FtsH12 contains the zinc-binding active site generally conserved among FtsH-type metalloproteases. Further, even the FtsH12 zinc-binding site is dispensable for its essential function. Phylogenetic analyses suggest that all AAA-type members of the Ycf2/FtsHi complex including Ycf2 evolved from the chloroplast-encoded membrane-bound AAA-protease FtsH of the ancestral endosymbiont. The Ycf2/FtsHi complex also contains an NAD-malate dehydrogenase, a proposed key enzyme for ATP production in chloroplasts in darkness or in non-photosynthetic plastids. These findings advance our understanding of this ATP-driven protein translocation system that is unique to the green lineage of photosynthetic eukaryotes.

RevDate: 2018-11-14

Bellec L, Cambon-Bonavita MA, Cueff-Gauchard V, et al (2018)

A Nematode of the Mid-Atlantic Ridge Hydrothermal Vents Harbors a Possible Symbiotic Relationship.

Frontiers in microbiology, 9:2246.

Deep-sea hydrothermal vent meiofauna have been the focus of recent research and the discovery of an abundant well-adapted free-living marine nematode on the Mid-Atlantic Ridge offers new perspectives on adaptations to the vent environment. Indeed, knowledge concerning biological interactions of microbes and meiofauna in marine extreme environments is scarce, especially for nematodes. In this study, we used microscopic observations [fluorescence in situ hybridization (FISH) and scanning electron microscopy (SEM)] and metabarcoding of 16S rRNA to characterize the bacterial community of the nematode species Oncholaimus dyvae, an overlooked but ecologically important vent organism. Detection of bacteria in the buccal cavity and on the cuticle (SEM) and epibionts in its intestine (FISH) suggests that O. dyvae harbors its own bacterial community. Molecular results and phylogenetic analysis show that bacteria associated with this species are related to symbiotic lineages typical of hydrothermal vent fauna, such as sulfur-oxidizing bacteria related to Epsilonproteobacteria and Gammaproteobacteria. This multi-approach study suggests a potential symbiotic role of bacteria with its nematode host and opens new research perspectives on vent meiofauna.

RevDate: 2018-11-26
CmpDate: 2018-11-26

Day PM, SM Theg (2018)

Evolution of protein transport to the chloroplast envelope membranes.

Photosynthesis research, 138(3):315-326.

Chloroplasts are descendants of an ancient endosymbiotic cyanobacterium that lived inside a eukaryotic cell. They inherited the prokaryotic double membrane envelope from cyanobacteria. This envelope contains prokaryotic protein sorting machineries including a Sec translocase and relatives of the central component of the bacterial outer membrane β-barrel assembly module. As the endosymbiont was integrated with the rest of the cell, the synthesis of most of its proteins shifted from the stroma to the host cytosol. This included nearly all the envelope proteins identified so far. Consequently, the overall biogenesis of the chloroplast envelope must be distinct from cyanobacteria. Envelope proteins initially approach their functional locations from the exterior rather than the interior. In many cases, they have been shown to use components of the general import pathway that also serves the stroma and thylakoids. If the ancient prokaryotic protein sorting machineries are still used for chloroplast envelope proteins, their activities must have been modified or combined with the general import pathway. In this review, we analyze the current knowledge pertaining to chloroplast envelope biogenesis and compare this to bacteria.

RevDate: 2018-11-14

Kageyama D, Ohno M, Sasaki T, et al (2017)

Feminizing Wolbachia endosymbiont disrupts maternal sex chromosome inheritance in a butterfly species.

Evolution letters, 1(5):232-244 pii:EVL328.

Wolbachia is a maternally inherited ubiquitous endosymbiotic bacterium of arthropods that displays a diverse repertoire of host reproductive manipulations. For the first time, we demonstrate that Wolbachia manipulates sex chromosome inheritance in a sexually reproducing insect. Eurema mandarina butterfly females on Tanegashima Island, Japan, are infected with the wFem Wolbachia strain and produce all-female offspring, while antibiotic treatment results in male offspring. Fluorescence in situ hybridization (FISH) revealed that wFem-positive and wFem-negative females have Z0 and WZ sex chromosome sets, respectively, demonstrating the predicted absence of the W chromosome in wFem-infected lineages. Genomic quantitative polymerase chain reaction (qPCR) analysis showed that wFem-positive females lay only Z0 eggs that carry a paternal Z, whereas females from lineages that are naturally wFem-negative lay both WZ and ZZ eggs. In contrast, antibiotic treatment of adult wFem females resulted in the production of Z0 and ZZ eggs, suggesting that this Wolbachia strain can disrupt the maternal inheritance of Z chromosomes. Moreover, most male offspring produced by antibiotic-treated wFem females had a ZZ karyotype, implying reduced survival of Z0 individuals in the absence of feminizing effects of Wolbachia. Antibiotic treatment of wFem-infected larvae induced male-specific splicing of the doublesex (dsx) gene transcript, causing an intersex phenotype. Thus, the absence of the female-determining W chromosome in Z0 individuals is functionally compensated by Wolbachia-mediated conversion of sex determination. We discuss how Wolbachia may manipulate the host chromosome inheritance and that Wolbachia may have acquired this coordinated dual mode of reproductive manipulation first by the evolution of female-determining function and then cytoplasmically induced disruption of sex chromosome inheritance.

RevDate: 2018-11-14

de Moraes LA, Muller C, Bueno RCOF, et al (2018)

Distribution and phylogenetics of whiteflies and their endosymbiont relationships after the Mediterranean species invasion in Brazil.

Scientific reports, 8(1):14589 pii:10.1038/s41598-018-32913-1.

The Bemisia tabaci is a polyphagous insect and a successful vector of plant viruses. B. tabaci is a species complex and in Brazil native species from the New World (NW) group, as well as the invasive species, Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) were reported. For better understanding the distribution of the different species four years after the Mediterranean species invasion in Brazil, whiteflies were collected from 237 locations throughout the country between the years of 2013 and 2017, species were identified and the facultative endosymbionts detected. The survey revealed that MEAM1 was the prevalent species found on major crops across Brazil. It is the only species present in North, Northwestern and Central Brazil and was associated with virus-infected plants. MED was found in five States from Southeast to South regions, infesting mainly ornamental plants and was not associated with virus-infected plants. The prevalent endosymbionts identified in MEAM1 were Hamiltonella and Rickettsia; and the mtCOI analysis revealed low genetic diversity for MEAM1. In contrast, several different endosymbionts were identified in MED including Hamiltonella, Rickettsia, Wolbachia and Arsenophonus; and two distinct genetic groups were found based on the mtCOI analysis. Monitoring the distribution of the whiteflies species in Brazil is essential for proper management of this pest.

RevDate: 2018-11-14

Ruocco N, Mutalipassi M, Pollio A, et al (2018)

First evidence of Halomicronema metazoicum (Cyanobacteria) free-living on Posidonia oceanica leaves.

PloS one, 13(10):e0204954 pii:PONE-D-18-10614.

Cyanobacteria contribute to the ecology of various marine environments, also for their symbioses, since some of them are common hosts of sponges and ascidians. They are also emerging as an important source of novel bioactive secondary metabolites in pharmacological (as anticancer drugs) and biotechnological applications. In the present work we isolated a cyanobacteria in a free-living state from leaves of the seagrass Posidonia oceanica leaves. This newly collected strain was then cultivated under two laboratory conditions, and then characterized by combining morphological observation and molecular studies based on 16S rRNA gene sequences analysis. The strain showed 99% pairwise sequence identity with Halomicronema metazoicum ITAC101, never isolated before as a free-living organisms, but firstly described as an endosymbiont of the Mediterranean marine spongae Petrosia ficiformis, under the form of a filamentous strain. Further studies will investigate the actual role of this cyanobacterium in the leaf stratum of P. oceanica leaves, given its demonstrated ability to influence the vitality and the life cycle of other organisms. In fact, its newly demonstrated free-living stage, described in this study, indicate that Phormidium-like cyanobacteria could play important roles in the ecology of benthic and planktonic communities.

RevDate: 2018-09-29

Wintermantel WM (2018)

Integration of Omics Approaches toward Understanding Whitefly Transmission of Viruses.

Advances in virus research, 102:199-223.

Viruses transmitted by whiteflies are predominantly classified as having either persistent circulative or semipersistent transmission, and the majority of studies have addressed transmission of viruses in the genera Begomovirus (family Geminiviridae) and Crinivirus (family Closteroviridae), respectively. Early studies on vector transmission primarily addressed individual aspects of transmission; however, with the breadth of new technology now available, an increasingly greater number of studies involve coordinated research that is beginning to assemble a more complete picture of how whiteflies and viruses have coevolved to facilitate transmission. In particular the integration of gene expression and metabolomic studies into broader research topics is providing knowledge of changes within the whitefly vector in response to the presence of viruses that would have been impossible to identify previously. Examples include comparative studies on the response of Bemisia tabaci to begomovirus and crinivirus infection of common host plants, evolution of whitefly endosymbiont relationships, and opportunities to evaluate responses to specific transmission-related events. Integration of metabolomics, as well as the application of electrical penetration graphing, can lead to an ability to monitor the changes that occur in vector insects associated with specific aspects of virus transmission. Through gaining more complete knowledge of the mechanisms behind whitefly transmission of viruses new control strategies will undoubtedly emerge for control of whiteflies and the viruses they transmit.

RevDate: 2018-11-14

Carpinone EM, Li Z, Mills MK, et al (2018)

Identification of putative effectors of the Type IV secretion system from the Wolbachia endosymbiont of Brugia malayi.

PloS one, 13(9):e0204736 pii:PONE-D-18-12540.

Wolbachia is an unculturable, intracellular bacterium that persists within an extremely broad range of arthropod and parasitic nematode hosts, where it is transmitted maternally to offspring via vertical transmission. In the filarial nematode Brugia malayi, a causative agent of human lymphatic filariasis, Wolbachia is an endosymbiont, and its presence is essential for proper nematode development, survival, and pathogenesis. While the elucidation of Wolbachia:nematode interactions that promote the bacterium's intracellular persistence is of great importance, research has been hampered due to the fact that Wolbachia cannot be cultured in the absence of host cells. The Wolbachia endosymbiont of B. malayi (wBm) has an active Type IV secretion system (T4SS). Here, we have screened 47 putative T4SS effector proteins of wBm for their ability to modulate growth or the cell biology of a typical eukaryotic cell, Saccharomyces cerevisiae. Five candidates strongly inhibited yeast growth upon expression, and 6 additional proteins showed toxicity in the presence of zinc and caffeine. Studies on the uptake of an endocytic vacuole-specific fluorescent marker, FM4-64, identified 4 proteins (wBm0076 wBm00114, wBm0447 and wBm0152) involved in vacuole membrane dynamics. The WAS(p)-family protein, wBm0076, was found to colocalize with yeast cortical actin patches and disrupted actin cytoskeleton dynamics upon expression. Deletion of the Arp2/3-activating protein, Abp1p, provided resistance to wBm0076 expression, suggesting a role for wBm0076 in regulating eukaryotic actin dynamics and cortical actin patch formation. Furthermore, wBm0152 was found to strongly disrupt endosome:vacuole cargo trafficking in yeast. This study provides molecular insight into the potential role of the T4SS in the Wolbachia endosymbiont:nematode relationship.

RevDate: 2018-11-26

Mix AK, Cenci U, Heimerl T, et al (2018)

Identification and Localization of Peroxisomal Biogenesis Proteins Indicates the Presence of Peroxisomes in the Cryptophyte Guillardia theta and Other "Chromalveolates".

Genome biology and evolution, 10(10):2834-2852 pii:5106030.

Peroxisomes are single-membrane-bound organelles with a huge metabolic versatility, including the degradation of fatty acids (β-oxidation) and the detoxification of reactive oxygen species as most conserved functions. Although peroxisomes seem to be present in the majority of investigated eukaryotes, where they are responsible for many eclectic and important spatially separated metabolic reactions, knowledge about their existence in the plethora of protists (eukaryotic microorganisms) is scarce. Here, we investigated genomic data of organisms containing complex plastids with red algal ancestry (so-called "chromalveolates") for the presence of genes encoding peroxins-factors specific for the biogenesis, maintenance, and division of peroxisomes in eukaryotic cells. Our focus was on the cryptophyte Guillardia theta, a marine microalga, which possesses two phylogenetically different nuclei of host and endosymbiont origin, respectively, thus being of enormous evolutionary significance. Besides the identification of a complete set of peroxins in G. theta, we heterologously localized selected factors as GFP fusion proteins via confocal and electron microscopy in the model diatom Phaeodactylum tricornutum. Furthermore, we show that peroxins, and thus most likely peroxisomes, are present in haptophytes as well as eustigmatophytes, brown algae, and alveolates including dinoflagellates, chromerids, and noncoccidian apicomplexans. Our results indicate that diatoms are not the only "chromalveolate" group devoid of the PTS2 receptor Pex7, and thus a PTS2-dependent peroxisomal import pathway, which seems to be absent in haptophytes (Emiliania huxleyi) as well. Moreover, important aspects of peroxisomal biosynthesis and protein import in "chromalveolates"are highlighted.

RevDate: 2018-11-24

Schön I, Kamiya T, Van den Berghe T, et al (2019)

Novel Cardinium strains in non-marine ostracod (Crustacea) hosts from natural populations.

Molecular phylogenetics and evolution, 130:406-415.

Endosymbiotic bacteria are known from many metazoan taxa, where they manipulate host biology and reproduction. Here, we used classic PCR amplification and direct DNA sequencing with universal primers for four different endosymbionts to test for their presence in more than 300 specimens of three recent non-marine ostracod superfamilies from different geographic areas and aquatic habitats. We verified these results with "high throughput" amplicon sequencing of 16S of nine selected specimens and evolutionary placement algorithms. The phylogenetic position of endosymbionts detected in ostracod hosts was compared to known endosymbionts from other metazoans. While Wolbachia, Spiroplasma and Rickettsia are absent, we find evidence for the general presence of Cardinium bacteria in natural populations of various non-marine ostracod species. Phylogenetic reconstructions based on Cardinium 16S data and estimates of genetic distances both indicate that Cardinium from ostracods are distantly related to Cardinium from Diptera and Nematoda but represent novel strains with a monophyletic origin. Cardinium bacteria from different ostracod hosts have genetic distances of up to 3.8%, providing evidence against recent and frequent horizontal transmissions amongst the three ostracod superfamilies. High throughput sequencing reveals more than 400 different 16S amplicon sequence variants in the investigated ostracods as well as the presence of different Cardinium strains within individual Eucypris virens and Heterocypris hosts. These results call for future, more in-depth investigations. Mapping Cardinium infections on COI trees of non-marine ostracod hosts shows that the occurrence of these endosymbionts is not linked to genetic species identity or phylogenetic host groups and, except for one ostracod morphospecies, prevalence never reaches 100%.

RevDate: 2018-11-27

Jacobson AL, Duffy S, P Sseruwagi (2018)

Whitefly-transmitted viruses threatening cassava production in Africa.

Current opinion in virology, 33:167-176 pii:S1879-6257(18)30112-3 [Epub ahead of print].

Emerging plant viruses are one of the greatest problems facing crop production worldwide, and have severe consequences in the developing world where subsistence farming is a major source of food production, and knowledge and resources for management are limited. In Africa, evolution of two viral disease complexes, cassava mosaic begomoviruses (CMBs) (Geminiviridae) and cassava brown streak viruses (CBSVs) (Potyviridae), have resulted in severe pandemics that continue to spread and threaten cassava production. Identification of genetically diverse and rapidly evolving CMBs and CBSVs, extensive genetic variation in the vector, Bemisia tabaci (Hemiptera: Aleyrodidae), and numerous secondary endosymbiont profiles that influence vector phenotypes suggest that complex local and regional vector-virus-plant-environment interactions may be driving the evolution and epidemiology of these viruses.

RevDate: 2018-11-14

Zeng Z, Fu Y, Guo D, et al (2018)

Bacterial endosymbiont Cardinium cSfur genome sequence provides insights for understanding the symbiotic relationship in Sogatella furcifera host.

BMC genomics, 19(1):688 pii:10.1186/s12864-018-5078-y.

BACKGROUND: Sogatella furcifera is a migratory pest that damages rice plants and causes severe economic losses. Due to its ability to annually migrate long distances, S. furcifera has emerged as a major pest of rice in several Asian countries. Symbiotic relationships of inherited bacteria with terrestrial arthropods have significant implications. The genus Cardinium is present in many types of arthropods, where it influences some host characteristics. We present a report of a newly identified strain of the bacterial endosymbiont Cardinium cSfur in S. furcifera.

RESULT: From the whole genome of S. furcifera previously sequenced by our laboratory, we assembled the whole genome sequence of Cardinium cSfur. The sequence comprised 1,103,593 bp with a GC content of 39.2%. The phylogenetic tree of the Bacteroides phylum to which Cardinium cSfur belongs suggests that Cardinium cSfur is closely related to the other strains (Cardinium cBtQ1 and cEper1) that are members of the Amoebophilaceae family. Genome comparison between the host-dependent endosymbiont including Cardinium cSfur and free-living bacteria revealed that the endosymbiont has a smaller genome size and lower GC content, and has lost some genes related to metabolism because of its special environment, which is similar to the genome pattern observed in other insect symbionts. Cardinium cSfur has limited metabolic capability, which makes it less contributive to metabolic and biosynthetic processes in its host. From our findings, we inferred that, to compensate for its limited metabolic capability, Cardinium cSfur harbors a relatively high proportion of transport proteins, which might act as the hub between it and its host. With its acquisition of the whole operon related to biotin synthesis and glycolysis related genes through HGT event, Cardinium cSfur seems to be undergoing changes while establishing a symbiotic relationship with its host.

CONCLUSION: A novel bacterial endosymbiont strain (Cardinium cSfur) has been discovered. A genomic analysis of the endosymbiont in S. furcifera suggests that its genome has undergone certain changes to facilitate its settlement in the host. The envisaged potential reproduction manipulative ability of the new endosymbiont strain in its S. furcifera host has vital implications in designing eco-friendly approaches to combat the insect pest.

RevDate: 2018-10-22

Zélé F, Santos JL, Godinho DP, et al (2018)

Wolbachia both aids and hampers the performance of spider mites on different host plants.

FEMS microbiology ecology, 94(12):.

In the last few decades, many studies have revealed the potential role of arthropod bacterial endosymbionts in shaping the host range of generalist herbivores and their performance on different host plants, which, in turn, might affect endosymbiont distribution in herbivore populations. We tested this by measuring the prevalence of endosymbionts in natural populations of the generalist spider mite Tetranychus urticae on different host plants. Focusing on Wolbachia, we then analysed how symbionts affected mite life-history traits on the same host plants in the laboratory. Overall, the prevalences of Cardinium and Rickettsia were low, whereas that of Wolbachia was high, with the highest values on bean and eggplant and the lowest on morning glory, tomato and zuchini. Although most mite life-history traits were affected by the plant species only, Wolbachia infection was detrimental for the egg-hatching rate on morning glory and zucchini, and led to a more female-biased sex ratio on morning glory and eggplant. These results suggest that endosymbionts may affect the host range of polyphagous herbivores, both by aiding and hampering their performance, depending on the host plant and on the life-history trait that affects performance the most. Conversely, endosymbiont spread may be facilitated or hindered by the plants on which infected herbivores occur.

RevDate: 2018-11-14

Humphreys AF, Halfar J, Ingle JC, et al (2018)

Effect of seawater temperature, pH, and nutrients on the distribution and character of low abundance shallow water benthic foraminifera in the Galápagos.

PloS one, 13(9):e0202746 pii:PONE-D-18-00255.

In order to help predict the effects of anthropogenic stressors on shallow water carbonate environments, it is important to focus research on regions containing natural oceanographic gradients, particularly with respect to interactions between oceanography and ecologically sensitive carbonate producers. The Galápagos Archipelago, an island chain in the eastern equatorial Pacific, spans a natural nutrient, pH, and temperature gradient due to the interaction of several major ocean currents. Further, the region is heavily impacted by the El Niño-Southern Oscillation (ENSO) and the Galápagos exhibited widespread coral bleaching and degradation following the strong ENSO events of 1982-1983 and 1997-1998. These findings are coupled with reports of unusually low abundances of time-averaged benthic foraminiferal assemblages throughout the region. Foraminifera, shelled single-celled protists, are sensitive to environmental change and rapidly respond to alterations to their surrounding environment, making them ideal indicator species for the study of reef water quality and health. Here, statistical models and analyses were used to compare modern shallow water benthic foraminiferal assemblages from 19 samples spanning the Galápagos Archipelago to predominant oceanographic parameters at each collection site. Fisher α diversity indices, Ternary diagrams, Canonical Correspondence Analysis, regression tree analysis and FORAM-Index (FI; a single metric index for evaluating water quality associated with reef development) implied a combined impact from ENSO and upwelling from Equatorial Undercurrent (EUC) waters to primarily impact foraminiferal abundances and drive assemblage patterns throughout the archipelago. For instance, repeated ENSO temperature anomalies might be responsible for low foraminiferal density, while chronically high nutrients and low aragonite saturation and low pH-induced by EUC upwelling and La Niña anomalies-likely inhibited post-ENSO recovery, and caused foraminiferal assemblages to exhibit a heterotrophic dominance in the southern archipelago. What resulted are low FI values in the southern collection sites, indicating environments not conducive to endosymbiont development and/or recovery.

RevDate: 2018-11-14

Pascar J, CH Chandler (2018)

A bioinformatics approach to identifying Wolbachia infections in arthropods.

PeerJ, 6:e5486 pii:5486.

Wolbachia is the most widespread endosymbiont, infecting >20% of arthropod species, and capable of drastically manipulating the host's reproductive mechanisms. Conventionally, diagnosis has relied on PCR amplification; however, PCR is not always a reliable diagnostic technique due to primer specificity, strain diversity, degree of infection and/or tissue sampled. Here, we look for evidence of Wolbachia infection across a wide array of arthropod species using a bioinformatic approach to detect the Wolbachia genes ftsZ, wsp, and the groE operon in next-generation sequencing samples available through the NCBI Sequence Read Archive. For samples showing signs of infection, we attempted to assemble entire Wolbachia genomes, and in order to better understand the relationships between hosts and symbionts, phylogenies were constructed using the assembled gene sequences. Out of the 34 species with positively identified infections, eight species of arthropod had not previously been recorded to harbor Wolbachia infection. All putative infections cluster with known representative strains belonging to supergroup A or B, which are known to only infect arthropods. This study presents an efficient bioinformatic approach for post-sequencing diagnosis and analysis of Wolbachia infection in arthropods.

RevDate: 2018-11-20

Compton KK, Hildreth SB, Helm RF, et al (2018)

Sinorhizobium meliloti Chemoreceptor McpV Senses Short-Chain Carboxylates via Direct Binding.

Journal of bacteriology, 200(23): pii:JB.00519-18.

Sinorhizobium meliloti is a soil-dwelling endosymbiont of alfalfa that has eight chemoreceptors to sense environmental stimuli during its free-living state. The functions of two receptors have been characterized, with McpU and McpX serving as general amino acid and quaternary ammonium compound sensors, respectively. Both receptors use a dual Cache (calcium channels and chemotaxis receptors) domain for ligand binding. We identified that the ligand-binding periplasmic region (PR) of McpV contains a single Cache domain. Homology modeling revealed that McpVPR is structurally similar to a sensor domain of a chemoreceptor with unknown function from Anaeromyxobacter dehalogenans, which crystallized with acetate in its binding pocket. We therefore assayed McpV for carboxylate binding and S. meliloti for carboxylate sensing. Differential scanning fluorimetry identified 10 potential ligands for McpVPR Nine of these are monocarboxylates with chain lengths between two and four carbons. We selected seven compounds for capillary assay analysis, which established positive chemotaxis of the S. meliloti wild type, with concentrations of peak attraction at 1 mM for acetate, propionate, pyruvate, and glycolate, and at 100 mM for formate and acetoacetate. Deletion of mcpV or mutation of residues essential for ligand coordination abolished positive chemotaxis to carboxylates. Using microcalorimetry, we determined that dissociation constants of the seven ligands with McpVPR were in the micromolar range. An McpVPR variant with a mutation in the ligand coordination site displayed no binding to isobutyrate or propionate. Of all the carboxylates tested as attractants, only glycolate was detected in alfalfa seed exudates. This work examines the relevance of carboxylates and their sensor to the rhizobium-legume interaction.IMPORTANCE Legumes share a unique association with certain soil-dwelling bacteria known broadly as rhizobia. Through concerted interorganismal communication, a legume allows intracellular infection by its cognate rhizobial species. The plant then forms an organ, the root nodule, dedicated to housing and supplying fixed carbon and nutrients to the bacteria. In return, the engulfed rhizobia, differentiated into bacteroids, fix atmospheric N2 into ammonium for the plant host. This interplay is of great benefit to the cultivation of legumes, such as alfalfa and soybeans, and is initiated by chemotaxis to the host plant. This study on carboxylate chemotaxis contributes to the understanding of rhizobial survival and competition in the rhizosphere and aids the development of commercial inoculants.

RevDate: 2018-09-10

Lin Z, Wang L, Chen M, et al (2018)

The acute transcriptomic response of coral-algae interactions to pH fluctuation.

Marine genomics pii:S1874-7787(18)30147-8 [Epub ahead of print].

Little is known about how the coral host and its endosymbiont interactions change when they are exposed to a sudden nonlinear environmental transformation, yet this is crucial to coral survival in extreme events. Here, we present a study that investigates the transcriptomic response of corals and their endosymbionts to an abrupt change in pH (pH 7.60 and 8.35). The transcriptome indicates that the endosymbiont demonstrates a synchronized downregulation in carbon acquisition and fixation processes and may result in photosynthetic dysfunction in endosymbiotic Symbiodinium, suggesting that the mutualistic continuum of coral-algae interactions is compromised in response to high-CO2 exposure. Transcriptomic data also shows that corals are still capable of calcifying in response to the low pH but could experience a series of negative effects on their energy dynamics, which including protein damage, DNA repair, ion transport, cellular apoptosis, calcification acclimation and maintenance of intracellular pH homeostasis and stress tolerance to pH swing. This suggests enhanced energy costs for coral metabolic adaptation. This study provides a deeper understanding of the biological basis related to the symbiotic corals in response to extreme future climate change and environmental variability.

RevDate: 2018-11-14

Alleman A, Hertweck KL, S Kambhampati (2018)

Random Genetic Drift and Selective Pressures Shaping the Blattabacterium Genome.

Scientific reports, 8(1):13427 pii:10.1038/s41598-018-31796-6.

Estimates suggest that at least half of all extant insect genera harbor obligate bacterial mutualists. Whereas an endosymbiotic relationship imparts many benefits upon host and symbiont alike, the intracellular lifestyle has profound effects on the bacterial genome. The obligate endosymbiont genome is a product of opposing forces: genes important to host survival are maintained through physiological constraint, contrasted by the fixation of deleterious mutations and genome erosion through random genetic drift. The obligate cockroach endosymbiont, Blattabacterium - providing nutritional augmentation to its host in the form of amino acid synthesis - displays radical genome alterations when compared to its most recent free-living relative Flavobacterium. To date, eight Blattabacterium genomes have been published, affording an unparalleled opportunity to examine the direction and magnitude of selective forces acting upon this group of symbionts. Here, we find that the Blattabacterium genome is experiencing a 10-fold increase in selection rate compared to Flavobacteria. Additionally, the proportion of selection events is largely negative in direction, with only a handful of loci exhibiting signatures of positive selection. These findings suggest that the Blattabacterium genome will continue to erode, potentially resulting in an endosymbiont with an even further reduced genome, as seen in other insect groups such as Hemiptera.

RevDate: 2018-11-14

Chung M, Teigen L, Liu H, et al (2018)

Targeted enrichment outperforms other enrichment techniques and enables more multi-species RNA-Seq analyses.

Scientific reports, 8(1):13377 pii:10.1038/s41598-018-31420-7.

Enrichment methodologies enable the analysis of minor members in multi-species transcriptomic data. We compared the standard enrichment of bacterial and eukaryotic mRNA to a targeted enrichment using an Agilent SureSelect (AgSS) capture for Brugia malayi, Aspergillus fumigatus, and the Wolbachia endosymbiont of B. malayi (wBm). Without introducing significant systematic bias, the AgSS quantitatively enriched samples, resulting in more reads mapping to the target organism. The AgSS-enriched libraries consistently had a positive linear correlation with their unenriched counterparts (r2 = 0.559-0.867). Up to a 2,242-fold enrichment of RNA from the target organism was obtained following a power law (r2 = 0.90), with the greatest fold enrichment achieved in samples with the largest ratio difference between the major and minor members. While using a single total library for prokaryote and eukaryote enrichment from a single RNA sample could be beneficial for samples where RNA is limiting, we observed a decrease in reads mapping to protein coding genes and an increase in multi-mapping reads to rRNAs in AgSS enrichments from eukaryotic total RNA libraries compared to eukaryotic poly(A)-enriched libraries. Our results support a recommendation of using AgSS targeted enrichment on poly(A)-enriched libraries for eukaryotic captures, and total RNA libraries for prokaryotic captures, to increase the robustness of multi-species transcriptomic studies.

RevDate: 2018-11-14

Tang XT, Cai L, Shen Y, et al (2018)

Diversity and evolution of the endosymbionts of Bemisia tabaci in China.

PeerJ, 6:e5516 pii:5516.

The whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a cryptic species complex, including members that are pests of global importance. This study presents a screening of B. tabaci species in China for infection by the primary endosymbiont, Portiera aleyrodidarum, and two secondary endosymbionts, Arsenophonus and Cardinium. The results showed that P. aleyrodidarum was detected in all B. tabaci individuals, while Arsenophonus was abundant in indigenous species of B. tabaci Asia II 1, Asia II 3, and China 1 but absent in the invasive species, Middle East-Asia Minor 1 (MEAM1); Cardinium presented in the Mediterranean (MED), Asia II 1 and Asia II 3 species but was rarely detected in the MEAM1 and China 1 species. Moreover, phylogenetic analyses revealed that the P. aleyrodidarum and mitochondrial cytochrome oxidase 1 (mtCO1) phylograms were similar and corresponding with the five distinct cryptic species clades to some extent, probably indicating an ancient infection followed by vertical transmission and subsequent co-evolutionary diversification. In contrast, the phylogenetic trees of Arsenophonus and Cardinium were incongruent with the mtCO1 phylogram, potentially indicating horizontal transmission in B. tabaci cryptic species complex. Taken together, our study showed the distinct infection status of endosymbionts in invasive and indigenous whiteflies; we also most likely indicated the co-evolution of primary endosymbiont and its host as well as the potential horizontal transfer of secondary endosymbionts.

RevDate: 2018-10-26

Cevidanes A, Di Cataldo S, Vera F, et al (2018)

Molecular Detection of Vector-Borne Pathogens in Rural Dogs and Associated Ctenocephalides felis Fleas (Siphonaptera: Pulicidae) in Easter Island (Chile).

Journal of medical entomology, 55(6):1659-1663.

The presence of vector-borne pathogens of veterinary and public health interest have received little attention in Chile. In Easter Island, in particular, a Chilean territory in the southeastern Pacific Ocean, no information is available. To fill this gap, 153 rural dogs were inspected for ectoparasites during a sterilization campaign carried out in 2016. Fleas were observed in 46% of the dogs, and Ctenocephalides felis (Bouché, 1835) was the only species present. Morphological identification of fleas was genetically confirmed using conventional polymerase chain reaction targeting the cox2 gene. No tick was observed in any dog. The presence of DNA of Rickettsia sp. (gltA and ompA fragment genes), Anaplasmataceae (16S rRNA), and Bartonella sp. (16S-23S ribosomal RNA intergenic spacer) was investigated in blood samples of 70 of the dogs and in 126 fleas analyzed in 68 pools that included 1-5 fleas. Rickettsial DNA was detected in 97% (n = 66) of the flea pools. Of these, 57 showed between 99 and 100% identity for both genes with published sequences of Candidatus Rickettsia asemboensis (CRa), six with Rickettsia felis, and one with Candidatus Rickettsia senegalensis. For two pools, gltA amplicons were identical to CRa but ompB amplicions showed 99-100% identity with R. felis. Anaplasmataceae DNA was detected in 16% (n = 11) pools. Sequenced amplicons showed highest identity with the endosymbiont Wolbachia pipientis. Bartonella DNA, showing 99% identity to Bartonella clarridgeiae, was detected in one pool (1.4%). No positive reaction was observed for any dog. This is the first detection of members of the 'R. felis-like' group other than R. felis in Chile.

RevDate: 2018-09-21

Dose B, Niehs SP, Scherlach K, et al (2018)

Unexpected Bacterial Origin of the Antibiotic Icosalide: Two-Tailed Depsipeptide Assembly in Multifarious Burkholderia Symbionts.

ACS chemical biology, 13(9):2414-2420.

Icosalide is an unusual two-tailed lipocyclopeptide antibiotic that was originally isolated from a fungal culture. Yet, its biosynthesis and ecological function have remained enigmatic. By genome mining and metabolic profiling of a bacterial endosymbiont (Burkholderia gladioli) of the pest beetle Lagria villosa, we unveiled a bacterial origin of icosalide. Functional analysis of the biosynthetic gene locus revealed an unprecedented nonribosomal peptide synthetase (NRPS) that incorporates two β-hydroxy acids by means of two starter condensation domains in different modules. This unusual assembly line, which may inspire new synthetic biology approaches, is widespread among many symbiotic Burkholderia species from diverse habitats. Biological assays showed that icosalide is active against entomopathogenic bacteria, thus adding to the chemical armory protecting beetle offspring. By creating a null mutant, we found that icosalide is a swarming inhibitor, which may play a role in symbiotic interactions and bears the potential for therapeutic applications.

RevDate: 2018-11-17

Cafiso A, Sassera D, Romeo C, et al (2019)

Midichloria mitochondrii, endosymbiont of Ixodes ricinus: evidence for the transmission to the vertebrate host during the tick blood meal.

Ticks and tick-borne diseases, 10(1):5-12.

Ticks are important vectors of a variety of pathogens affecting humans and other animals, but they also harbor numerous microorganisms whose role is still limitedly investigated. Ixodes ricinus harbors the endosymbiont Midichloria mitochondrii, which is localized in ovaries and in salivary glands. The bacterium is vertically transmitted and is present in 100% of wild adult females, while prevalence values drop after some generations under laboratory conditions. Molecular and serological evidences showed that M. mitochondrii molecules are transmitted to the vertebrate hosts by I. ricinus during the blood meal. Our work was focused on monitoring M. mitochondrii antigens and DNA in a vertebrate model after infestation with I. ricinus for a time-span of four months. Two groups of rabbits were infested with I. ricinus females, respectively from the wild (naturally infected with the symbiont) and laboratory strain (lab; considered devoid of M. mitochondrii after quantitative PCR investigations) and screened using molecular and serological assays at nine time points. M. mitochondrii presence was detected in rabbits infested with wild I. ricinus ticks, but surprisingly also in those infested with lab ticks, albeit at later time points. This result prompted a more sensitive molecular screening of lab ticks, which were found to harbor very low symbiont loads. Our results indicate that transmission of the bacterium occurs even at low bacterial loads, and that antibody response against M. mitochondrii antigens begins within one week post-infestation with wild I. ricinus. Circulating DNA was detected in the blood of rabbits belonging to both groups up to the end of the experiment, suggesting a replication of the symbiont inside the vertebrate host.

RevDate: 2018-08-28

Brown AMV (2018)

Endosymbionts of Plant-Parasitic Nematodes.

Annual review of phytopathology, 56:225-242.

Some of the most agriculturally important plant-parasitic nematodes (PPNs) harbor endosymbionts. Extensive work in other systems has shown that endosymbionts can have major effects on host virulence and biology. This review highlights the discovery, development, and diversity of PPN endosymbionts, incorporating inferences from genomic data. Cardinium, reported from five PPN hosts to date, is characterized by its presence in the esophageal glands and other tissues, with a discontinuous distribution across populations, and genomic data suggestive of horizontal gene exchange. Xiphinematobacter occurs in at least 27 species of dagger nematode in the ovaries and gut epithelial cells, where genomic data suggest it may serve in nutritional supplementation. Wolbachia, reported in just three PPNs, appears to have an ancient history in the Pratylenchidae and displays broad tissue distribution and genomic features intermediate between parasitic and reproductive groups. Finally, a model is described that integrates these insights to explain patterns of endosymbiont replacement.

RevDate: 2018-11-14

Takagi H, Kimoto K, Fujiki T, et al (2018)

Effect of nutritional condition on photosymbiotic consortium of cultured Globigerinoides sacculifer (Rhizaria, Foraminifera).

Symbiosis (Philadelphia, Pa.), 76(1):25-39.

Several foraminifers found in warm and low-nutrient ocean surface water have photosynthetic algae as endosymbionts (photosymbiosis). To understand the trophic interactions, we studied Globigerinoides sacculifer, a spinose planktic foraminifer that has a dinoflagellate endosymbiont. We controlled two nutritional factors, feeding and inorganic nutrients in the seawater. The growth of the host and the symbionts and the photophysiological parameters were monitored under four experimental conditions. The results demonstrated that the holobionts primarily relied on phagotrophy for growth. The foraminifers grew considerably, and the chlorophyll a content per foraminifer, which is an indicator of the symbiont population, increased in the fed groups, but not in the unfed groups. The nutrient-rich seawater used for some of the cultures made no difference in either the growth or photophysiology of the holobionts. These observations indicated that the symbionts mainly utilized metabolites from the hosts for photosynthesis rather than inorganic nutrients in the seawater. Additionally, we observed that the symbionts in the starved hosts maintained their photosynthetic capability for at least 12 days, and that the hosts maintained at least some symbionts until gametogenesis was achieved. This suggests that the hosts have to retain the symbionts as an energy source for reproduction. The symbionts may also play an indispensable role in the metabolic activities of the hosts including waste transport or essential compound synthesis. Overall, our results revealed a novel mode of photosymbiosis in planktic foraminifers which contrasts with that found in benthic photosymbiotic foraminifers and corals.

RevDate: 2018-10-20

Richardson KM, Griffin PC, Lee SF, et al (2018)

A Wolbachia infection from Drosophila that causes cytoplasmic incompatibility despite low prevalence and densities in males.

Heredity pii:10.1038/s41437-018-0133-7 [Epub ahead of print].

Wolbachia bacteria are common insect endosymbionts transmitted maternally and capable of spreading through insect populations by cytoplasmic incompatibility (CI) when infected males cause embryo death after mating with uninfected females. Selection in the Wolbachia endosymbiont occurs on female hosts and is expected to favour strong maternal transmission to female offspring, even at the cost of reduced CI. With maternal leakage, nuclear genes are expected to be selected to suppress cytoplasmic incompatibility caused by males while also reducing any deleterious effects associated with the infection. Here we describe a new type of Wolbachia strain from Drosophila pseudotakahashii likely to have arisen from evolutionary processes on host and/or Wolbachia genomes. This strain is often absent from adult male offspring, but always transmitted to females. It leads to males with low or non-detectable Wolbachia that nevertheless show CI. When detected in adult males, the infection has a low density relative to that in females, a phenomenon not previously seen in Wolbachia infections of Drosophila. This Wolbachia strain is common in natural populations, and shows reduced CI when older (infected) males are crossed. These patterns highlight that endosymbionts can have strong sex-specific effects and that high frequency Wolbachia strains persist through effects on female reproduction. Female-limited Wolbachia infections may be of applied interest if the low level of Wolbachia in males reduces deleterious fitness effects on the host.

RevDate: 2018-09-21

Shi PQ, Wang L, Liu Y, et al (2018)

Infection dynamics of endosymbionts reveal three novel localization patterns of Rickettsia during the development of whitefly Bemisia tabaci.

FEMS microbiology ecology, 94(11):.

The whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) is a severe agricultural pest that harbors at least seven endosymbionts. Many important aspects of the symbiosis mechanism between these bacterial endosymbionts and their hosts are poorly understood, such as endosymbiont proliferation dynamics, spatial distribution and titer regulation during host development. In this study, infection by bacterial endosymbionts in the whitefly B. tabaci Middle East-Asia Minor-1 (MEAM1, formerly B biotype) South China population, their infection titers in various stages of whitefly host development and their spatial localization were investigated. Results revealed that the MEAM1 B. tabaci harbors the primary symbiont Portiera and secondary symbionts Rickettsia and Hamiltonella. The titers of these three endosymbionts increased with the development of their B. tabaci host. Significant proliferation of Portiera and Hamiltonella mainly occurred during the second to fourth instar nymphal stages, while Rickettsia proliferated mainly during adult eclosion. Fluorescence in situ hybridization analysis of B. tabaci adults revealed three novel infection patterns of Rickettsia: assemblage in the bacteriocytes that scattered through the entire abdomen of the female host, localization in wax glands and localization in the colleterial gland. These novel infection patterns may help to uncover the function of Rickettsia in its insect hosts.

RevDate: 2018-11-14

Anderson EE, Wilson C, Knap AH, et al (2018)

Summer diatom blooms in the eastern North Pacific gyre investigated with a long-endurance autonomous surface vehicle.

PeerJ, 6:e5387 pii:5387.

Satellite chlorophyll a (chl a) observations have repeatedly noted summertime phytoplankton blooms in the North Pacific subtropical gyre (NPSG), a region of open ocean that is far removed from any land-derived or Ekman upwelling nutrient sources. These blooms are dominated by N2-fixing diatom-cyanobacteria associations of the diatom genera Rhizosolenia Brightwell and Hemiaulus Ehrenberg. Their nitrogen fixing endosymbiont, Richelia intracellularis J.A. Schmidt, is hypothesized to be critical to the development of blooms in this nitrogen limited region. However, due to the remote location and unpredictable duration of the summer blooms, prolonged in situ observations are rare outside of the Station ALOHA time-series off of Hawai'i. In summer, 2015, a proof-of-concept mission using the autonomous vehicle, Honey Badger (Wave Glider SV2; Liquid Robotics, a Boeing company, Sunnyvale, CA, USA), collected near-surface (<20 m) observations in the NPSG using hydrographic, meteorological, optical, and imaging sensors designed to focus on phytoplankton abundance, distribution, and physiology of this bloom-forming region. Hemiaulus and Rhizosolenia cell abundance was determined using digital holography for the entire June-November mission. Honey Badger was not able to reach the 30°N subtropical front region where most of the satellite chl a blooms have been observed, but near-real time navigational control allowed it to transect two blooms near 25°N. The two taxa did not co-occur in large numbers, rather the blooms were dominated by either Hemiaulus or Rhizosolenia. The August 2-4, 2015 bloom was comprised of 96% Hemiaulus and the second bloom, August 15-17, 2015, was dominated by Rhizosolenia (75%). The holograms also imaged undisturbed, fragile Hemiaulus aggregates throughout the sampled area at ∼10 L-1. Aggregated Hemiaulus represented the entire observed population at times and had a widespread distribution independent of the summer export pulse, a dominant annual event suggested to be mediated by aggregate fluxes. Aggregate occurrence was not consistent with a density dependent formation mechanism and may represent a natural growth form in undisturbed conditions. The photosynthetic potential index (Fv:Fm) increased from ∼0.4 to ∼0.6 during both blooms indicating a robust, active phytoplankton community in the blooms. The diel pattern of Fv:Fm (nocturnal maximum; diurnal minimum) was consistent with macronutrient limitation throughout the mission with no evidence of Fe-limitation despite the presence of nitrogen fixing diatom-diazotroph assemblages. During the 5-month mission, Honey Badger covered ∼5,690 km (3,070 nautical miles), acquired 9,336 holograms, and reliably transmitted data onshore in near real-time. Software issues developed with the active fluorescence sensor that terminated measurements in early September. Although images were still useful at the end of the mission, fouling of the LISST-Holo optics was considerable, and appeared to be the most significant issue facing deployments of this duration.

RevDate: 2018-08-14

Wang Y, Mao L, Sun Y, et al (2018)

A Novel Francisella-Like Endosymbiont in Haemaphysalis longicornis and Hyalomma asiaticum, China.

Vector borne and zoonotic diseases (Larchmont, N.Y.) [Epub ahead of print].

Francisella tularensis causes a highly infectious zoonotic disease tularemia. Both Haemaphysalis longicornis and Hyalomma asiaticum are widely distributed in China, but the presence of Francisella and Francisella-like endosymbionts (FLEs) in the two tick species is poorly understood. Therefore, a total of 627 H. longicornis (471 adults and 156 nymphs) and 88 Hy. asiaticum ticks (adults) were collected, of which 88 were from Bole of Xinjiang, 236 from Liaoyang, and 176 from Shenyang of Liaoning, and 215 from Wuhan of Hubei. Notably, five H. longicornis pools from Liaoyang of Liaoning province might have harbored F. tularensis, showing a minimum prevalence of 2.12% (5/236). This study should alert the health department and veterinarians working within the region to prevent and control the emergence of tularemia. After the screening of 16S rRNA and tul4 genes, the results revealed that FLEs were detected in Hy. asiaticum ticks in Bole and in H. longicornis ticks in Liaoyang and Shenyang. Their infection rate was 100% (88/88), 3.39% (8/236 is a minimum), and 8.52% (15/176), respectively. Phylogenetic analyses indicated that the sequence named bole in Hy. Asiaticum from Bole, the sequence named liaoyang1 in H. longicornis from Liaoyang, and the sequence named shanyang1 in H. longicornis from Shenyang shared consistent 16S rRNA sequence, and the difference between Chinese FLEs and the known FLEs was obvious. These findings suggest that this FLE species might be a potentially novel FLE circulating in H. longicornis and Hy. asiaticum from China.

RevDate: 2018-09-07

Kruse A, Ramsey JS, Johnson R, et al (2018)

Candidatus Liberibacter asiaticus Minimally Alters Expression of Immunity and Metabolism Proteins in Hemolymph of Diaphorina citri, the Insect Vector of Huanglongbing.

Journal of proteome research, 17(9):2995-3011.

Huanglongbing (HLB), also known as citrus greening disease, is the most serious disease of citrus plants. It is associated with the Gram-negative bacterium ' Candidatus Liberibacter asiaticus' (CLas), which is transmitted between host plants by the hemipteran insect vector Diaphorina citri in a circulative, propagative manner involving specific interactions with various insect tissues including the hemolymph, fluid that occupies the body cavity akin to insect blood. High resolution quantitative mass spectrometry was performed to investigate the effect of CLas exposure on D. citri hemolymph at the proteome level. In contrast to the broad proteome effects on hundreds of proteins and a diverse array of metabolic pathways previously reported in gut and whole insect proteome analyses, the effect of CLas on the hemolymph was observed to be highly specific, restricted to key immunity and metabolism pathways, and lower in magnitude than that previously observed in the whole insect body and gut. Vitellogenins were abundantly expressed and CLas-responsive. Gene-specific RNA expression analysis suggests that these proteins are expressed in both male and female insects and may have roles outside of reproductive vitellogenesis. Proteins for fatty acid synthesis were found to be up-regulated, along with metabolic proteins associated with energy production, supported at the organismal level by the previously published observation that D. citri individuals experience a higher level of hunger when reared on CLas-infected plants. Prediction of post-translational modifications identified hemolymph proteins with phosphorylation and acetylation upon CLas exposure. Proteins derived from the three most prominent bacterial endosymbionts of the psyllid were also detected in the hemolymph, and several of these have predicted secretion signals. A DNAK protein, the bacterial HSP70, detected in the hemolymph expressed from Wolbachia pipientis was predicted to encode a eukaryotic nuclear localization signal. Taken together, these data show specific changes to immunity and metabolism in D. citri hemolymph involving host and endosymbiont proteins. These data provide a novel context for proteomic changes seen in other D. citri tissues in response to CLas and align with organismal data on the effects of CLas on D. citri metabolism and reproduction.

RevDate: 2018-11-14

Mukherjee S, Joardar N, Mondal S, et al (2018)

Quinolone-fused cyclic sulfonamide as a novel benign antifilarial agent.

Scientific reports, 8(1):12073 pii:10.1038/s41598-018-30610-7.

Search of potent antifilarial drugs has been a major thrust area in tropical medicine research over the decades. Herein, we report 4,7-dimethyl-3,4,7,8-tetrahydro-3λ6-[1,2]thiazino[4,3-f]quinoline-3,3,8-trione (8l) as a new class of antifilarial agent which is extremely potent, with lethality against all the developmental stages (oocyte, microfilaria and adult) of the filarial parasite Setaria cervi. Molecular investigation on its mode of action revealed that 8l is a typical inducer of reactive oxygen species that triggers oxidative stress inside the filarid and further signals induction of apoptosis by activating both intrinsic and extrinsic pathways. Moreover, 8l is also active against Wolbachia, the essential endosymbiont of several human infectious filarids. Selective toxicity against filarial parasites and non-toxic nature in rat model were found as unique traits of 8l to be a future medicine. Taken en masse, this maiden report on a novel quinolone fused cyclic sulfonamide presents a promising therapeutic lead for lymphatic filariasis in future.

RevDate: 2018-11-14

Budachetri K, Kumar D, Crispell G, et al (2018)

The tick endosymbiont Candidatus Midichloria mitochondrii and selenoproteins are essential for the growth of Rickettsia parkeri in the Gulf Coast tick vector.

Microbiome, 6(1):141 pii:10.1186/s40168-018-0524-2.

BACKGROUND: Pathogen colonization inside tick tissues is a significant aspect of the overall competence of a vector. Amblyomma maculatum is a competent vector of the spotted fever group rickettsiae, Rickettsia parkeri. When R. parkeri colonizes its tick host, it has the opportunity to dynamically interact with not just its host but with the endosymbionts living within it, and this enables it to modulate the tick's defenses by regulating tick gene expression. The microbiome in A. maculatum is dominated by two endosymbiont microbes: a Francisella-like endosymbiont (FLE) and Candidatus Midichloria mitochondrii (CMM). A range of selenium-containing proteins (selenoproteins) in A. maculatum ticks protects them from oxidative stress during blood feeding and pathogen infections. Here, we investigated rickettsial multiplication in the presence of tick endosymbionts and characterized the functional significance of selenoproteins during R. parkeri replication in the tick.

RESULTS: FLE and CMM were quantified throughout the tick life stages by quantitative PCR in R. parkeri-infected and uninfected ticks. R. parkeri infection was found to decrease the FLE numbers but CMM thrived across the tick life cycle. Our qRT-PCR analysis indicated that the transcripts of genes with functions related to redox (selenogenes) were upregulated in ticks infected with R. parkeri. Three differentially expressed proteins, selenoprotein M, selenoprotein O, and selenoprotein S were silenced to examine their functional significance during rickettsial replication within the tick tissues. Gene silencing of the target genes was found to impair R. parkeri colonization in the tick vector. Knockdown of the selenogenes triggered a compensatory response from other selenogenes, as observed by changes in gene expression, but oxidative stress levels and endoplasmic reticulum stress inside the ticks were also found to have heightened.

CONCLUSIONS: This study illustrates the potential of this new research model for augmenting our understanding of the pathogen interactions occurring within tick hosts and the important roles that symbionts and various tick factors play in regulating pathogen growth.

RevDate: 2018-11-14

Manzano-Marín A, Coeur d'acier A, Clamens AL, et al (2018)

A Freeloader? The Highly Eroded Yet Large Genome of the Serratia symbiotica Symbiont of Cinara strobi.

Genome biology and evolution, 10(9):2178-2189 pii:5068483.

Genome reduction is pervasive among maternally inherited bacterial endosymbionts. This genome reduction can eventually lead to serious deterioration of essential metabolic pathways, thus rendering an obligate endosymbiont unable to provide essential nutrients to its host. This loss of essential pathways can lead to either symbiont complementation (sharing of the nutrient production with a novel co-obligate symbiont) or symbiont replacement (complete takeover of nutrient production by the novel symbiont). However, the process by which these two evolutionary events happen remains somewhat enigmatic by the lack of examples of intermediate stages of this process. Cinara aphids (Hemiptera: Aphididae) typically harbor two obligate bacterial symbionts: Buchnera and Serratia symbiotica. However, the latter has been replaced by different bacterial taxa in specific lineages, and thus species within this aphid lineage could provide important clues into the process of symbiont replacement. In the present study, using 16S rRNA high-throughput amplicon sequencing, we determined that the aphid Cinara strobi harbors not two, but three fixed bacterial symbionts: Buchnera aphidicola, a Sodalis sp., and S. symbiotica. Through genome assembly and genome-based metabolic inference, we have found that only the first two symbionts (Buchnera and Sodalis) actually contribute to the hosts' supply of essential nutrients while S. symbiotica has become unable to contribute towards this task. We found that S. symbiotica has a rather large and highly eroded genome which codes only for a few proteins and displays extensive pseudogenization. Thus, we propose an ongoing symbiont replacement within C. strobi, in which a once "competent" S. symbiotica does no longer contribute towards the beneficial association. These results suggest that in dual symbiotic systems, when a substitute cosymbiont is available, genome deterioration can precede genome reduction and a symbiont can be maintained despite the apparent lack of benefit to its host.

RevDate: 2018-09-29

Jiang W, Zhu J, Wu Y, et al (2018)

Influence of Wolbachia infection on mitochondrial DNA variation in the genus Polytremis (Lepidoptera: Hesperiidae).

Molecular phylogenetics and evolution, 129:158-170.

The maternally inherited obligate bacteria Wolbachia is known for infecting the reproductive tissues of a wide range of arthropods and can contribute to phylogenetically discordant patterns between mtDNA and nDNA. In this study, we tested for an association between mito-nuclear discordance in Polytremis and Wolbachia infection. Six of the 17 species of Polytremis were found to be infected with Wolbachia. Overall, 34% (70/204) of Polytremis specimens were Wolbachia positive and three strains of Wolbachia identified using a wsp marker were further characterized as six strains based on MLST markers. Wolbachia acquisition in Polytremis appears to occur mainly through horizontal transmission rather than codivergence based on comparison of the divergence times of Wolbachia and Polytremis species. At the intraspecific level, one of the Wolbachia infections (wNas1) is associated with reduced mtDNA polymorphism in the infected Polytremis population. At the interspecific level, there is one case of mito-nuclear discordance likely caused by introgression of P. fukia mtDNA into P. nascens driven by another Wolbachia strain (wNas3). Based on an absence of infected males, we suspect that one Wolbachia strain (wNas2) affects sex ratio, but the phenotypic effects of the other strains are unclear. These data reveal a dynamic interaction between Polytremis and Wolbachia endosymbionts affecting patterns of mtDNA variation.

RevDate: 2018-08-31

Yurchenko V, J Lukeš (2018)

Parasites and their (endo)symbiotic microbes.

Parasitology, 145(10):1261-1264.

Thanks to modern molecular biology methods, our understanding of the impact of (endo)symbiotic bacteria on parasitic protists and helminths is growing fast. In this issue, 9 papers have been brought together that describe various facets of the relationships between these microorganisms, reveal their range and high frequency, as well as their capacity to create novel biological complexity. Comparative analyses of these host-endosymbiont interactions indicate that there may be no discrete types of relationships but rather a continuum ranging from a dispensable endosymbiont minimally integrated within the host cell to organelles, such as mitochondria and plastids that evolved into an indispensable, deeply integrated components of the cell. We hope that this series of studies on parasites and (endo)symbiotic bacteria will increase awareness about these relationships and their representation in microbial ecology models.

RevDate: 2018-11-14

Grosche C, Diehl A, Rensing SA, et al (2018)

Iron-Sulfur Cluster Biosynthesis in Algae with Complex Plastids.

Genome biology and evolution, 10(8):2061-2071 pii:5063867.

Plastids surrounded by four membranes harbor a special compartment between the outer and inner plastid membrane pair, the so-called periplastidal compartment (PPC). This cellular structure is usually presumed to be the reduced cytoplasm of a eukaryotic phototrophic endosymbiont, which was integrated into a host cell and streamlined into a plastid with a complex membrane structure. Up to date, no mitochondrion or mitochondrion-related organelle has been identified in the PPC of any representative. However, two prominent groups, the cryptophytes and the chlorarachniophytes, still harbor a reduced cell nucleus of symbiont origin, the nucleomorph, in their PPCs. Generally, many cytoplasmic and nucleus-located eukaryotic proteins need an iron-sulfur cofactor for their functionality. Beside some exceptions, their synthesis is depending on a so-called iron-sulfur complex (ISC) assembly machinery located in the mitochondrion. This machinery provides the cytoplasm with a still unknown sulfur component, which is then converted into iron-sulfur clusters via a cytosolic iron-sulfur protein assembly (CIA) machinery. Here, we investigated if a CIA machinery is present in mitochondrion-lacking PPCs. By using bioinformatic screens and in vivo-localizations of candidate proteins, we show that the presence of a PPC-specific CIA machinery correlates with the presence of a nucleomorph. Phylogenetic analyses of PPC- and host specific CIA components additionally indicate a complex evolution of the CIA machineries in organisms having plastids surrounded by four membranes.

RevDate: 2018-11-14

Matsuo E, Y Inagaki (2018)

Patterns in evolutionary origins of heme, chlorophyll a and isopentenyl diphosphate biosynthetic pathways suggest non-photosynthetic periods prior to plastid replacements in dinoflagellates.

PeerJ, 6:e5345 pii:5345.

Background: The ancestral dinoflagellate most likely established a peridinin-containing plastid, which have been inherited in the extant photosynthetic descendants. However, kareniacean dinoflagellates and Lepidodinium species were known to bear "non-canonical" plastids lacking peridinin, which were established through haptophyte and green algal endosymbioses, respectively. For plastid function and maintenance, the aforementioned dinoflagellates were known to use nucleus-encoded proteins vertically inherited from the ancestral dinoflagellates (vertically inherited- or VI-type), and those acquired from non-dinoflagellate organisms (including the endosymbiont). These observations indicated that the proteomes of the non-canonical plastids derived from a haptophyte and a green alga were modified by "exogenous" genes acquired from non-dinoflagellate organisms. However, there was no systematic evaluation addressing how "exogenous" genes reshaped individual metabolic pathways localized in a non-canonical plastid.

Results: In this study, we surveyed transcriptomic data from two kareniacean species (Karenia brevis and Karlodinium veneficum) and Lepidodinium chlorophorum, and identified proteins involved in three plastid metabolic pathways synthesizing chlorophyll a (Chl a), heme and isoprene. The origins of the individual proteins of our interest were investigated, and we assessed how the three pathways were modified before and after the algal endosymbioses, which gave rise to the current non-canonical plastids. We observed a clear difference in the contribution of VI-type proteins across the three pathways. In both Karenia/Karlodinium and Lepidodinium, we observed a substantial contribution of VI-type proteins to the isoprene and heme biosynthesises. In sharp contrast, VI-type protein was barely detected in the Chl a biosynthesis in the three dinoflagellates.

Discussion: Pioneering works hypothesized that the ancestral kareniacean species had lost the photosynthetic activity prior to haptophyte endosymbiosis. The absence of VI-type proteins in the Chl a biosynthetic pathway in Karenia or Karlodinium is in good agreement with the putative non-photosynthetic nature proposed for their ancestor. The dominance of proteins with haptophyte origin in the Karenia/Karlodinium pathway suggests that their ancestor rebuilt the particular pathway by genes acquired from the endosymbiont. Likewise, we here propose that the ancestral Lepidodinium likely experienced a non-photosynthetic period and discarded the entire Chl a biosynthetic pathway prior to the green algal endosymbiosis. Nevertheless, Lepidodinium rebuilt the pathway by genes transferred from phylogenetically diverse organisms, rather than the green algal endosymbiont. We explore the reasons why green algal genes were barely utilized to reconstruct the Lepidodinium pathway.

RevDate: 2018-11-14

Fisher ML, Watson DW, Osborne JA, et al (2018)

Growth kinetics of endosymbiont Wolbachia in the common bed bug, Cimex lectularius.

Scientific reports, 8(1):11444 pii:10.1038/s41598-018-29682-2.

The common bed bug, Cimex lectularius harbors the endosymbiotic microorganism, Wolbachia (wCle), in a gonad-associated bacteriome as an obligate nutritional mutualist. The obligatory nature of this association suggests that all individuals in C. lectularius populations would be infected with wCle. However, studies spanning the past several decades have reported variation in both infection frequency and relative abundance of wCle in field-collected samples of bed bugs. Since the growth kinetics of wCle is poorly understood, the objective of this study was to quantify wCle over the life cycle of two strains of C. lectularius. Our results highlight that wCle is dynamic during bed bug development, changing relative to life stage, intermolt stage, and blood-fed status. These results suggest new hypotheses about the coordination of Wolbachia growth and regression with its host's physiology and endocrine events. The observed quantitative modulation of wCle during the bed bug life cycle and during periods of starvation may explain the disparities in wCle infections reported in field-collected C. lectularius.

RevDate: 2018-11-14

Río Bártulos C, Rogers MB, Williams TA, et al (2018)

Mitochondrial Glycolysis in a Major Lineage of Eukaryotes.

Genome biology and evolution, 10(9):2310-2325 pii:5061552.

The establishment of the mitochondrion is seen as a transformational step in the origin of eukaryotes. With the mitochondrion came bioenergetic freedom to explore novel evolutionary space leading to the eukaryotic radiation known today. The tight integration of the bacterial endosymbiont with its archaeal host was accompanied by a massive endosymbiotic gene transfer resulting in a small mitochondrial genome which is just a ghost of the original incoming bacterial genome. This endosymbiotic gene transfer resulted in the loss of many genes, both from the bacterial symbiont as well the archaeal host. Loss of genes encoding redundant functions resulted in a replacement of the bulk of the host's metabolism for those originating from the endosymbiont. Glycolysis is one such metabolic pathway in which the original archaeal enzymes have been replaced by bacterial enzymes from the endosymbiont. Glycolysis is a major catabolic pathway that provides cellular energy from the breakdown of glucose. The glycolytic pathway of eukaryotes appears to be bacterial in origin, and in well-studied model eukaryotes it takes place in the cytosol. In contrast, here we demonstrate that the latter stages of glycolysis take place in the mitochondria of stramenopiles, a diverse and ecologically important lineage of eukaryotes. Although our work is based on a limited sample of stramenopiles, it leaves open the possibility that the mitochondrial targeting of glycolytic enzymes in stramenopiles might represent the ancestral state for eukaryotes.

RevDate: 2018-08-16

Rangsrikitphoti P, DG Durnford (2018)

Transcriptome Profiling of Bigelowiella natans in Response to Light Stress.

The Journal of eukaryotic microbiology [Epub ahead of print].

Bigelowiella natans is a marine chlorarachniophyte whose plastid was acquired secondarily via endosymbiosis with a green alga. During plastid evolution, the photosynthetic endosymbiont would have integrated with the host metabolic pathways. This would require the evolution and coordination of strategies to cope with changes in light intensity that includes changes in the expression of both endosymbiont and host-derived genes. To investigate the transcriptional response to light intensity in chlorarachniophytes, we conducted an RNA-seq experiment to identify differentially expressed genes following a 4-h shift to high or very-low light. A shift to high light altered the expression of over 2,000 genes, many involved with photosynthesis, PSII assembly, primary metabolism, and reactive-oxygen scavenging. These changes are an attempt to optimize photosynthesis and increase energy sinks for excess reductant, while minimizing photooxidative stress. A transfer to very-low light resulted in a lower photosynthetic performance and metabolic alteration, reflecting an energy-limited state. Genes located on the nucleomorph, the vestigial nucleus in the plastid, had few changes in expression in either light treatment, indicating this organelle has relinquished most transcriptional control to the nucleus. Overall, during plastid origin, both host and transferred endosymbiont genes evolved a harmonized transcriptional network to respond to a classic photosynthetic stress.

RevDate: 2018-11-14

Rossitto De Marchi B, Kinene T, Mbora Wainaina J, et al (2018)

Comparative transcriptome analysis reveals genetic diversity in the endosymbiont Hamiltonella between native and exotic populations of Bemisia tabaci from Brazil.

PloS one, 13(7):e0201411 pii:PONE-D-18-08374.

The whitefly, Bemisia tabaci, is a species complex of more than 40 cryptic species and a major agricultural pest. It causes extensive damage to plants mainly by transmitting plant viruses. There is still a lack of genomic data available for the different whitefly species found in Brazil and their bacterial endosymbionts. Understanding the genetic and transcriptomic composition of these insect pests, the viruses they transmit and the microbiota is crucial to sustainable solutions for farmers to control whiteflies. Illumina RNA-Seq was used to obtain the transcriptome of individual whiteflies from 10 different populations from Brazil including Middle East-Asia Minor 1 (MEAM1), Mediterranean (MED) and New World 2 (NW2). Raw reads were assembled using CLC Genomics Workbench and subsequently mapped to reference genomes. We obtained whitefly complete mitochondrial genomes and draft genomes from the facultative bacterial endosymbiont Hamiltonella for further phylogenetic analyses. In addition, nucleotide sequences of the GroEL chaperonin gene from Hamiltonella from different populations were obtained and analysed. There was concordance in the species clustering using the whitefly complete mitogenome and the mtCOI gene tree. On the other hand, the phylogenetic analysis using the 12 ORF's of Hamiltonella clustered the native species NW2 apart from the exotics MEAM1 and MED. In addition, the amino acid analysis of GroEL chaperonin revealed a deletion only in Hamiltonella infecting NW2 among whiteflies populations analysed which was further confirmed by PCR and Sanger sequencing. The genomic data obtained in this study will aid understanding the functions that Hamiltonella may have in whitefly biology and serve as a reference for further studies regarding whiteflies in Brazil.

RevDate: 2018-11-14

James EB, Feng H, ACC Wilson (2018)

mTOR Complex 1 Implicated in Aphid/Buchnera Host/Symbiont Integration.

G3 (Bethesda, Md.), 8(9):3083-3091 pii:g3.118.200398.

Obligate nutritional endosymbioses are arguably the most intimate of all interspecific associations. While many insect nutritional endosymbioses are well studied, a full picture of how two disparate organisms, a bacterial endosymbiont and a eukaryotic host, are integrated is still lacking. The mTOR pathway is known to integrate nutritional conditions with cell growth and survival in eukaryotes. Characterization and localization of amino acid transporters in aphids suggest the mTOR pathway as a point of integration between an aphid host and its amino acid-provisioning endosymbiont Buchnera aphidicola The mTOR pathway is unannotated in aphids and unstudied in any nutritional endosymbiosis. We annotated mTOR pathway genes in two aphid species, Acyrthosiphon pisum and Myzus persicae, using both BLASTp searches and Hidden Markov Models. Using previously collected RNAseq data we constructed new reference transcriptomes for bacteriocyte, gut, and whole insect tissue for three lines of M. persicae Annotation of the mTOR pathway identified homologs of all known invertebrate mTOR genes in both aphid species with some duplications. Differential expression analysis showed that genes specific to the amino acid-sensitive mTOR Complex 1 were more highly expressed in bacteriocytes than genes specific to the amino acid-insensitive mTOR Complex 2. Almost all mTOR genes involved in sensing amino acids showed higher expression in bacteriocytes than in whole insect tissue. When compared to gut, the putative glutamine/arginine sensing transporter ACYPI000333, an ortholog of SLC38A9, showed 6.5 times higher expression in bacteriocytes. Our results suggest that the mTOR pathway may be functionally important in mediating integration of Buchnera into aphid growth and reproduction.

RevDate: 2018-10-11
CmpDate: 2018-10-11

Wei Z, Liu Y, Feng K, et al (2018)

The divergence between fungal and bacterial communities in seasonal and spatial variations of wastewater treatment plants.

The Science of the total environment, 628-629:969-978.

In this study, quantitative PCR (qPCR) and high-throughput sequencing were used to simultaneously examine both bacteria and fungi across temporal and spatial scales in activated sludge from wastewater treatment plants (WWTPs). The ratio of fungi to bacteria was 0.43% on average after accounting for the multicopies in 16S rRNA gene (54.63%), indicating the number of fungi was far lower than bacteria in active sludge. The Miseq sequencing results revealed obvious seasonal and spatial variations in bacterial and fungal distribution patterns in WWTPs. Compared to bacteria, fungi showed a lower divergence in alpha and beta diversity, and exhibited less taxonomic diversity in both abundant and rare subcommunities at the class level, suggesting that the fungal community was less variable in this artificial ecosystem. Such variation of microbial communities was significantly correlated with geographical distance, DO, temperature, HRT, SRT, COD, TN and TP. In activated sludge, the main function of bacteria was chemoheterotrophy, fermentation, and nitrogen cycling processes, while the dominant functional guilds of fungi were saprotroph, animal pathogen, and animal endosymbiont. Moreover, both bacteria and fungi could play important roles in the degradation of toxicants, like hydrocarbon and aromatic compounds.

RevDate: 2018-11-14

Li Y, Liles MR, KM Halanych (2018)

Endosymbiont genomes yield clues of tubeworm success.

The ISME journal, 12(11):2785-2795.

Forty years after discovery of chemosynthetic symbiosis in the tubeworm Riftia pachyptila, how organisms maintain their unique host-symbiont associations at the cellular level is still largely unknown. Previous studies primarily focus on symbionts associated with host lineages living in hydrothermal vents. To understand physiological adaptations and evolution in these holobiont systems in markedly different habitats, we characterized four novel siboglinid-symbiont genomes spanning deep-sea seep and sedimented environments. Our comparative analyses suggest that all sampled siboglinid chemoautotrophic symbionts, except for frenulate symbionts, can use both rTCA and Calvin cycle for carbon fixation. We hypothesize that over evolutionary time siboglinids have been able to utilize different bacterial lineages allowing greater metabolic flexibility of carbon fixation (e.g., rTCA) enabling tubeworms to thrive in more reducing habitats, such as vents and seeps. Moreover, we show that sulfur metabolism and molecular mechanisms related to initial infection are remarkably conserved across chemoautotrophic symbionts in different habitats. Unexpectedly, we find that the ability to use hydrogen, as an additional energy source, is potentially more widespread than previously recognized. Our comparative genomic results help elucidate potential mechanisms used to allow chemosynthetically dependent holobionts adapt to, and evolve in, different environments.

RevDate: 2018-11-16

Moretti R, Yen PS, Houé V, et al (2018)

Combining Wolbachia-induced sterility and virus protection to fight Aedes albopictus-borne viruses.

PLoS neglected tropical diseases, 12(7):e0006626 pii:PNTD-D-18-00260.

Among the strategies targeting vector control, the exploitation of the endosymbiont Wolbachia to produce sterile males and/or invasive females with reduced vector competence seems to be promising. A new Aedes albopictus transinfection (ARwP-M) was generated by introducing wMel Wolbachia in the ARwP line which had been established previously by replacing wAlbA and wAlbB Wolbachia with the wPip strain. Various infection and fitness parameters were studied by comparing ARwP-M, ARwP and wild-type (SANG population) Ae. albopictus sharing the same genetic background. Moreover, the vector competence of ARwP-M related to chikungunya, dengue and zika viruses was evaluated in comparison with ARwP. ARwP-M showed a 100% rate of maternal inheritance of wMel and wPip Wolbachia. Survival, female fecundity and egg fertility did not show to differ between the three Ae. albopictus lines. Crosses between ARwP-M males and SANG females were fully unfertile regardless of male age while egg hatch in reverse crosses increased from 0 to about 17% with SANG males aging from 3 to 17 days. When competing with SANG males for SANG females, ARwP-M males induced a level of sterility significantly higher than that expected for an equal mating competitiveness (mean Fried index of 1.71 instead of 1). The overall Wolbachia density in ARwP-M females was about 15 fold higher than in ARwP, mostly due to the wMel infection. This feature corresponded to a strongly reduced vector competence for chikungunya and dengue viruses (in both cases, 5 and 0% rates of transmission at 14 and 21 days post infection) with respect to ARwP females. Results regarding Zika virus did not highlight significant differences between ARwP-M and ARwP. However, none of the tested ARwP-M females was capable at transmitting ZIKV. These findings are expected to promote the exploitation of Wolbachia to suppress the wild-type Ae. albopictus populations.

RevDate: 2018-10-30
CmpDate: 2018-10-30

Kamani J, Harrus S, Nachum-Biala Y, et al (2018)

Pathogenic and endosymbiont apicomplexans in Ctenocephalides felis (Siphonaptera: Pulicidae) from cats in Jerusalem, Israel.

Comparative immunology, microbiology and infectious diseases, 57:29-33.

This study was conducted to determine the prevalence of pathogenic and endosymbiont apicomplexans in the cat flea, Ctenocephalides felis (Bouché) infesting 185 stray cats in Jerusalem, Israel using PCR assay and sequencing approach. Two pathogens, Hepatozoon felis and Babesia vogeli and an endosymbiont Steinina ctenocephali were detected in 1.9%, 0.2% and 5.8% of 685 C. felis evaluated respectively. There was a significant association (p < 0.05) between the prevalence of H. felis and the sex of cats hosting the fleas as well as the season of sampling but not for age or health status of the cats or sex of the fleas tested. Prevalence of S. ctenocephali was significantly (p < 0.001) associated with season, being higher in the warm season. This report represents the first molecular detection of S. ctenocephali in C. felis. Further studies to determine the potential role of C. felis in the epidemiology of H. felis and B. vogeli are warranted.

RevDate: 2018-11-14

Li LH, Zhang Y, Zhu D, et al (2018)

Endosymbionts Alter Larva-to-Nymph Transstadial Transmission of Babesia microti in Rhipicephalus haemaphysaloides Ticks.

Frontiers in microbiology, 9:1415.

Maternally inherited endosymbionts inhabit a variety of arthropods. Some of them can protect the arthropod host against a wide range of pathogens. However, very little is known about the association between endosymbionts and pathogen susceptibility in ticks. The present study investigated the effect of endosymbionts on larva-to-nymph transstadial transmission of Babesia microti by Rhipicephalus haemaphysaloides ticks. Engorged female ticks were injected with PBS, ciprofloxacin or kanamycin. The offspring larvae were used to infest B. microti-positive mice. Prevalence of B. microti among the nymphs in different treatment groups and its association with endosymbiont density in the larvae were analyzed. The results showed that the prevalence of B. microti in the kanamycin-treated group (63.9%, 95% confidence interval (CI): 52.8-75.0%) was higher than that in the PBS (23.6%, 95% CI: 13.8-33.4%) or ciprofloxacin-treated (25.0%, 95% CI: 15.0-35.0%) groups. This increased prevalence was associated with reduced density of Coxiella-like endosymbiont but was not related to the density of Rickettsia-like endosymbiont. No direct evidence has previously been reported about the impact of Coxiella-like endosymbiont on pathogen susceptibility in ticks. This study reveals that endosymbionts are potentially important defensive symbionts of R. haemaphysaloides which may influence the colonization or susceptibility of B. microti in the tick host.


ESP Quick Facts

ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

ESP Support

In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

ESP Rationale

Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

ESP Goal

In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

ESP Usage

Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

ESP Content

When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

ESP Help

Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

ESP Plans

With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.

Electronic Scholarly Publishing
21454 NE 143rd Street
Woodinville, WA 98077

E-mail: RJR8222 @

Papers in Classical Genetics

The ESP began as an effort to share a handful of key papers from the early days of classical genetics. Now the collection has grown to include hundreds of papers, in full-text format.

Digital Books

Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).


ESP now offers a much improved and expanded collection of timelines, designed to give the user choice over subject matter and dates.


Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )