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Bibliography on: Endosymbiosis

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ESP: PubMed Auto Bibliography 19 Apr 2019 at 01:45 Created: 

Endosymbiosis

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: 2019-04-17

Muñoz-Leal S, Macedo C, Gonçalves TC, et al (2019)

Detected microorganisms and new geographic records of Ornithodoros rietcorreai (Acari: Argasidae) from northern Brazil.

Ticks and tick-borne diseases pii:S1877-959X(18)30422-9 [Epub ahead of print].

Reliable data on distributional ranges of soft ticks (Argasidae) and assessments of putative tick-borne agents enhance the understanding on tick-associated microorganisms. A total of 96 ticks morphologicaly and molecularly identified as Ornithodoros rietcorreai were collected in Tocantins State, Brazil, using Noireau traps with living bait as CO2 source. Ninety-six ticks (54 nymphs, 32 males, 10 females) with different engorgement degrees were collected. Fourty-seven (48.9%) of them were individually screened by PCR for detecting bacteria of Anaplasmataceae family and genera Rickettsia, and Borrelia. The presence of protozoans of the genus Babesia was assessed as well. Fourty seven ticks were submitted to analysis. Nine ticks (19.1%) yielded sequences for gltA and htrA genes most identical with a series of endosymbiont rickettsiae and Rickettsia bellii, respectively. Upon two ticks (4.2%) we retrieved DNA of a potential new Wolbachia sp., and DNA of a putative novel Hepatozoon was characterized from three (6.4%) specimens. No DNA of Babesia or Borrelia was detected. Remarkably, amplicons of unidentified eukaryotic organisms, most closely related with apicomplexans but also with dinoflagellates (91% of identity after BLAST analyses), were recovered from two ticks (4.2%) using primers designed for Babesia 18S rRNA gene. Our records expand the distribution of O. rietcorreai into Brazilian Cerrado biome and introduce the occurrence of microorganisms in this tick species.

RevDate: 2019-04-17

Dhaygude K, Nair A, Johansson H, et al (2019)

The first draft genomes of the ant Formica exsecta, and its Wolbachia endosymbiont reveal extensive gene transfer from endosymbiont to host.

BMC genomics, 20(1):301 pii:10.1186/s12864-019-5665-6.

BACKGROUND: Adapting to changes in the environment is the foundation of species survival, and is usually thought to be a gradual process. However, transposable elements (TEs), epigenetic modifications, and/or genetic material acquired from other organisms by means of horizontal gene transfer (HGTs), can also lead to novel adaptive traits. Social insects form dense societies, which attract and maintain extra- and intracellular accessory inhabitants, which may facilitate gene transfer between species. The wood ant Formica exsecta (Formicidae; Hymenoptera), is a common ant species throughout the Palearctic region. The species is a well-established model for studies of ecological characteristics and evolutionary conflict.

RESULTS: In this study, we sequenced and assembled draft genomes for F. exsecta and its endosymbiont Wolbachia. The F. exsecta draft genome is 277.7 Mb long; we identify 13,767 protein coding genes, for which we provide gene ontology and protein domain annotations. This is also the first report of a Wolbachia genome from ants, and provides insights into the phylogenetic position of this endosymbiont. We also identified multiple horizontal gene transfer events (HGTs) from Wolbachia to F. exsecta. Some of these HGTs have also occurred in parallel in multiple other insect genomes, highlighting the extent of HGTs in eukaryotes.

CONCLUSION: We present the first draft genome of ant F. exsecta, and its endosymbiont Wolbachia (wFex), and show considerable rates of gene transfer from the symbiont to the host. We expect that especially the F. exsecta genome will be valuable resource in further exploration of the molecular basis of the evolution of social organization.

RevDate: 2019-04-16

Hugo MH, Kaech H, Ganesanandamoorthy P, et al (2019)

Evolutionary costs and benefits of infection with diverse strains of Spiroplasma in pea aphids.

Evolution; international journal of organic evolution [Epub ahead of print].

The heritable endosymbiont Spiroplasma infects many insects and has repeatedly evolved the ability to protect its hosts against different parasites. Defenses do not come for free to the host, and theory predicts that more costly symbionts need to provide stronger benefits to persist in host populations. We investigated the costs and benefits of Spiroplasma infections in pea aphids (Acyrthosiphon pisum), testing 12 bacterial strains from three different clades. Virtually all strains decreased aphid lifespan and reproduction, but only two had a (weak) protective effect against the parasitoid Aphidius ervi, an important natural enemy of pea aphids. Spiroplasma induced fitness costs were variable, with strains from the most slowly evolving clade reaching higher titers and curtailing aphid lifespan more strongly than other strains. Some Spiroplasma strains shared their host with a second endosymbiont, Regiella insecticola. Although the result of an unfortunate handling error, these co-infections proved instructive, because they showed that the cost of infection with Spiroplasma may be attenuated in the presence of Regiella. These results suggest that mechanisms other than protection against A. ervi maintain pea aphid infections with diverse strains of Spiroplasma, and that studying them in isolation will not provide a complete picture of their effects on host fitness. This article is protected by copyright. All rights reserved.

RevDate: 2019-04-16

Chong RA, Park H, NA Moran (2019)

Genome evolution of the obligate endosymbiont Buchnera aphidicola.

Molecular biology and evolution pii:5466460 [Epub ahead of print].

An evolutionary consequence of uniparentally transmitted symbiosis is degradation of symbiont genomes. We use the system of aphids and their maternally inherited obligate endosymbiont, Buchnera aphidicola, to explore the evolutionary process of genome degradation. We compared complete genome sequences for 39 Buchnera strains, including 23 newly sequenced symbiont genomes from diverse aphid hosts. We reconstructed the genome of the most recent shared Buchnera ancestor, which contained 616 protein-coding genes, and 39 RNA genes. The extent of subsequent gene loss varied across lineages, resulting in modern genomes ranging from 412 to 646 kilobases and containing 354 to 587 protein-coding genes. Loss events were highly non-random across loci. Genes involved in replication, transcription, translation, and amino acid biosynthesis are largely retained, whereas genes underlying ornithine biosynthesis, stress responses and transcriptional regulation were lost repeatedly. Aside from losses, gene order is almost completely stable. The main exceptions involve movement between plasmid and chromosome locations of genes underlying tryptophan and leucine biosynthesis and supporting nutrition of aphid hosts. This set of complete genomes enabled tests for signatures of positive diversifying selection. Of 371 Buchnera genes tested, 29 genes show strong support for ongoing positive selection. These include genes encoding outer membrane porins that are expected to be involved in direct interactions with hosts. Collectively, these results indicate that extensive genome reduction occurred in the ancestral Buchnera prior to aphid diversification and that reduction has continued since, with losses greater in some lineages and for some loci.

RevDate: 2019-04-11

Boevé JL, R Rozenberg (2019)

Berberis sawfly contains toxic peptides not only at larval stage.

Die Naturwissenschaften, 106(5-6):14 pii:10.1007/s00114-019-1613-1.

Livestock can die from grazing in areas where larvae of certain Argidae or Pergidae species containing toxic peptides occur in mass. However, it remains unknown whether other stages also contain these compounds. Here, single specimens of larvae, prepupae, and adults of Arge berberidis, plus samples of its cocoons and larval feces, were analyzed by liquid chromatography-tandem mass spectrometry. The four peptides, pergidin (Perg), 4-valinepergidin (VPerg), dephosphorylated pergidin (dpPerg), and lophyrotomin (LGln), were detected in each of the three stages. Peptide concentrations, in percentage fresh weight, increased from larval up to adult stages, with mean values from 0.044 to 0.125% for Perg, 0.008 to 0.023% for VPerg, and 0.064 to 0.116% for LGln, whereas dpPerg never exceeded 0.001%. The concentrations of this latter peptide averaged 0.002% in the cocoon built by the prepupa, and nearly no peptides were detected in larval feces. Moreover, the concentrations of the three main peptides (Perg, LGln, and VPerg) tended to be correlated with each other in larvae and especially in adults. It is likely that peptide production, purportedly by an endosymbiont, stops at prepupal stage and that concentration of the peptides increases from prepupa to adult due to a decrease of body weight.

RevDate: 2019-04-14

Gallo-Franco JJ, Duque-Gamboa DN, N Toro-Perea (2019)

Bacterial communities of Aphis gossypii and Myzus persicae (Hemiptera: Aphididae) from pepper crops (Capsicum sp.).

Scientific reports, 9(1):5766 pii:10.1038/s41598-019-42232-8.

Insects harbor a wide variety of microorganisms that form complex and changing communities and play an important role in the biology and evolution of their hosts. Aphids have been used as model organisms to study microorganism-insect interactions. Almost all aphids are infected with the obligate endosymbiont Buchnera aphidicola and can host different bacteria that allow them to acquire traits of agronomic importance, such as resistance to high temperatures and/or defense against natural enemies. However, the bacterial communities of most aphid species remain poorly characterized. In this study, we used high-throughput DNA sequencing to characterize the bacterial communities of Aphis gossypii and Myzus persicae from two cultivable pepper species, Capsicum frutescens (Tabasco variety) and C. annuum (Cayenne variety), in four localities of southwestern Colombia. In addition, we evaluated the dynamics of A. gossypii-associated microorganisms on a seasonal basis. Our results show that the bacterial communities of A. gossypii and M. persicae are dominated by the primary endosymbiont B. aphidicola, while the presence of the facultative symbiont Arsenophonus sp. was only detected in one A. gossypii population from cayenne pepper. In addition to these two known symbionts, eight bacterial OTUs were identified that presented a frequency of 1% or more in at least one of the analyzed populations. The results show that the bacterial communities of aphids associated with pepper crops appears to be structured according to the host aphid species and the geographical location, while no differences were observed in the diversity of bacteria between host plants. Finally, the diversity and abundance of the A. gossypii bacterial community was variable among the four sampling points evaluated over the year and showed a relation with the aphid's population dynamics. This study represents the first approach to the knowledge of the bacterial community present in chili pepper aphids from Colombia. Nevertheless, more in-depth studies, including replicates, are required to confirm the patterns observed in the microbial communities of aphids from pepper crops.

RevDate: 2019-04-09

Jäckle O, Seah BKB, Tietjen M, et al (2019)

Chemosynthetic symbiont with a drastically reduced genome serves as primary energy storage in the marine flatworm Paracatenula.

Proceedings of the National Academy of Sciences of the United States of America pii:1818995116 [Epub ahead of print].

Hosts of chemoautotrophic bacteria typically have much higher biomass than their symbionts and consume symbiont cells for nutrition. In contrast to this, chemoautotrophic Candidatus Riegeria symbionts in mouthless Paracatenula flatworms comprise up to half of the biomass of the consortium. Each species of Paracatenula harbors a specific Ca Riegeria, and the endosymbionts have been vertically transmitted for at least 500 million years. Such prolonged strict vertical transmission leads to streamlining of symbiont genomes, and the retained physiological capacities reveal the functions the symbionts provide to their hosts. Here, we studied a species of Paracatenula from Sant'Andrea, Elba, Italy, using genomics, gene expression, imaging analyses, as well as targeted and untargeted MS. We show that its symbiont, Ca R. santandreae has a drastically smaller genome (1.34 Mb) than the symbiont´s free-living relatives (4.29-4.97 Mb) but retains a versatile and energy-efficient metabolism. It encodes and expresses a complete intermediary carbon metabolism and enhanced carbon fixation through anaplerosis and accumulates massive intracellular inclusions such as sulfur, polyhydroxyalkanoates, and carbohydrates. Compared with symbiotic and free-living chemoautotrophs, Ca R. santandreae's versatility in energy storage is unparalleled in chemoautotrophs with such compact genomes. Transmission EM as well as host and symbiont expression data suggest that Ca R. santandreae largely provisions its host via outer-membrane vesicle secretion. With its high share of biomass in the symbiosis and large standing stocks of carbon and energy reserves, it has a unique role for bacterial symbionts-serving as the primary energy storage for its animal host.

RevDate: 2019-04-10

Chen W, Shakir S, Bigham M, et al (2019)

Genome sequence of the corn leaf aphid (Rhopalosiphum maidis Fitch).

GigaScience, 8(4):.

BACKGROUND: The corn leaf aphid (Rhopalosiphum maidis Fitch) is the most economically damaging aphid pest on maize (Zea mays), one of the world's most important grain crops. In addition to causing direct damage by removing photoassimilates, R. maidis transmits several destructive maize viruses, including maize yellow dwarf virus, barley yellow dwarf virus, sugarcane mosaic virus, and cucumber mosaic virus.

FINDINGS: The genome of a parthenogenetically reproducing R. maidis clone was assembled with a combination of Pacific Biosciences (207-fold coverage) and Illumina (83-fold coverage) sequencing. The 689 assembled contigs, which have an N50 size of 9.0 megabases (Mb) and a low level of heterozygosity, were clustered using Phase Genomics Hi-C interaction maps. Consistent with the commonly observed 2n = 8 karyotype of R. maidis, most of the contigs (473 spanning 321 Mb) were successfully oriented into 4 scaffolds. The genome assembly captured the full length of 95.8% of the core eukaryotic genes, indicating that it is highly complete. Repetitive sequences accounted for 21.2% of the assembly, and a total of 17,629 protein-coding genes were predicted with integrated evidence from ab initio and homology-based gene predictions and transcriptome sequences generated with both Pacific Biosciences and Illumina. An analysis of likely horizontally transferred genes identified 2 from bacteria, 7 from fungi, 2 from protozoa, and 9 from algae. Repeat elements, transposons, and genes encoding likely detoxification enzymes (cytochrome P450s, glutathione S-transferases, carboxylesterases, uridine diphosphate-glucosyltransferases, and ABC transporters) were identified in the genome sequence. Other than Buchnera aphidicola (642,929 base pairs, 602 genes), no endosymbiont bacteria were found in R. maidis.

CONCLUSIONS: A high-quality R. maidis genome was assembled at the chromosome level. This genome sequence will enable further research related to ecological interactions, virus transmission, pesticide resistance, and other aspects of R. maidis biology. It also serves as a valuable resource for comparative investigation of other aphid species.

RevDate: 2019-04-12
CmpDate: 2019-04-11

Tsagmo Ngoune JM, Reveillaud J, Sempere G, et al (2019)

The composition and abundance of bacterial communities residing in the gut of Glossina palpalis palpalis captured in two sites of southern Cameroon.

Parasites & vectors, 12(1):151 pii:10.1186/s13071-019-3402-2.

BACKGROUND: A number of reports have demonstrated the role of insect bacterial flora on their host's physiology and metabolism. The tsetse host and vector of trypanosomes responsible for human sleeping sickness (human African trypanosomiasis, HAT) and nagana in animals (African animal trypanosomiasis, AAT) carry bacteria that influence its diet and immune processes. However, the mechanisms involved in these processes remain poorly documented. This underscores the need for increased research into the bacterial flora composition and structure of tsetse flies. The aim of this study was to identify the diversity and relative abundance of bacterial genera in Glossina palpalis palpalis flies collected in two trypanosomiasis foci in Cameroon.

METHODS: Samples of G. p. palpalis which were either negative or naturally trypanosome-positive were collected in two foci located in southern Cameroon (Campo and Bipindi). Using the V3V4 and V4 variable regions of the small subunit of the 16S ribosomal RNA gene, we analyzed the respective bacteriome of the flies' midguts.

RESULTS: We identified ten bacterial genera. In addition, we observed that the relative abundance of the obligate endosymbiont Wigglesworthia was highly prominent (around 99%), regardless of the analyzed region. The remaining genera represented approximately 1% of the bacterial flora, and were composed of Salmonella, Spiroplasma, Sphingomonas, Methylobacterium, Acidibacter, Tsukamurella, Serratia, Kluyvera and an unidentified bacterium. The genus Sodalis was present but with a very low abundance. Globally, no statistically significant difference was found between the bacterial compositions of flies from the two foci, and between positive and trypanosome-negative flies. However, Salmonella and Serratia were only described in trypanosome-negative flies, suggesting a potential role for these two bacteria in fly refractoriness to trypanosome infection. In addition, our study showed the V4 region of the small subunit of the 16S ribosomal RNA gene was more efficient than the V3V4 region at describing the totality of the bacterial diversity.

CONCLUSIONS: A very large diversity of bacteria was identified with the discovering of species reported to secrete anti-parasitic compounds or to modulate vector competence in other insects. For future studies, the analyses should be enlarged with larger sampling including foci from several countries.

RevDate: 2019-04-02

Spang A, Stairs CW, Dombrowski N, et al (2019)

Proposal of the reverse flow model for the origin of the eukaryotic cell based on comparative analyses of Asgard archaeal metabolism.

Nature microbiology pii:10.1038/s41564-019-0406-9 [Epub ahead of print].

The origin of eukaryotes represents an unresolved puzzle in evolutionary biology. Current research suggests that eukaryotes evolved from a merger between a host of archaeal descent and an alphaproteobacterial endosymbiont. The discovery of the Asgard archaea, a proposed archaeal superphylum that includes Lokiarchaeota, Thorarchaeota, Odinarchaeota and Heimdallarchaeota suggested to comprise the closest archaeal relatives of eukaryotes, has helped to elucidate the identity of the putative archaeal host. Whereas Lokiarchaeota are assumed to employ a hydrogen-dependent metabolism, little is known about the metabolic potential of other members of the Asgard superphylum. We infer the central metabolic pathways of Asgard archaea using comparative genomics and phylogenetics to be able to refine current models for the origin of eukaryotes. Our analyses indicate that Thorarchaeota and Lokiarchaeota encode proteins necessary for carbon fixation via the Wood-Ljungdahl pathway and for obtaining reducing equivalents from organic substrates. By contrast, Heimdallarchaeum LC2 and LC3 genomes encode enzymes potentially enabling the oxidation of organic substrates using nitrate or oxygen as electron acceptors. The gene repertoire of Heimdallarchaeum AB125 and Odinarchaeum indicates that these organisms can ferment organic substrates and conserve energy by coupling ferredoxin reoxidation to respiratory proton reduction. Altogether, our genome analyses suggest that Asgard representatives are primarily organoheterotrophs with variable capacity for hydrogen consumption and production. On this basis, we propose the 'reverse flow model', an updated symbiogenetic model for the origin of eukaryotes that involves electron or hydrogen flow from an organoheterotrophic archaeal host to a bacterial symbiont.

RevDate: 2019-04-03

Ali H, Muhammad A, Sanda NB, et al (2019)

Pyrosequencing Uncovers a Shift in Bacterial Communities Across Life Stages of Octodonta nipae (Coleoptera: Chrysomelidae).

Frontiers in microbiology, 10:466.

Bacterial symbionts of insects affect a wide array of host traits including fitness and immunity. Octodonta nipae (Maulik), commonly known as hispid leaf beetle is a destructive palm pest around the world. Understanding the dynamics of microbiota is essential to unravel the complex interplay between O. nipae and its bacterial symbionts. In this study, bacterial 16S rRNA V3-V4 region was targeted to decipher the diversity and dynamics of bacterial symbionts across different life stages [eggs, larvae, pupae, and adult (male and female)] and reproductive organs (ovaries and testis) of O. nipae. Clustering analysis at ≥97% similarity threshold produced 3,959 operational taxonomic units (OTUs) that belonged to nine different phyla. Proteobacteria, Actinobacteria, and Firmicutes represented the bulk of taxa that underwent notable changes during metamorphosis. Enterobacteriaceae and Dermabacteraceae were the most abundant families in immature stages (eggs, larvae, and pupae), while Anaplasmataceae family was dominated in adults (male and female) and reproductive organs (ovaries and testis). The genus Serratia and Lactococcus were most abundant in eggs, whereas Pantoea and Brachybacterium represented the bulk of larvae and pupae microbiota. Interestingly the genus Wolbachia found positive to all tested samples and was recorded extremely high (>64%) in the adults and reproductive organs. The bacteria varied across the developmental stages and responsible for various metabolic activities. Selection choice exerted by the insect host as a result of its age or developmental stage could be the main reason to ascertain the shift in the bacteria populations. Maternally inherited Wolbachia was found to be an obligate endosymbiont infecting all tested life stages, body parts, and tissues. These outcomes foster our understanding of the intricate associations between bacteria and O. nipae and will incorporate in devising novel pest control strategies against this palm pest.

RevDate: 2019-04-15

Hajialilo E, Rezaeian M, Niyyati M, et al (2019)

Molecular characterization of bacterial, viral and fungal endosymbionts of Acanthamoeba isolates in keratitis patients of Iran.

Experimental parasitology, 200:48-54 pii:S0014-4894(19)30005-0 [Epub ahead of print].

Free-living amoebae belong to the genus Acanthamoeba; can feed on microbial population by phagocytosis, and with the capability to act as a reservoir and a vehicle of microorganisms to susceptible host. Therefore, the role of endosymbiosis in the pathogenesis of Acanthamoeba is complex and not fully understood. The aim of the present study was to identify bacterial, fungal, and human adenovirus (HADV) endosymbionts as well as evaluating the endosymbionts role of such organisms in the pathogenesis of Acanthamoeba in keratitis patients living in Iran. Fifteen Acanthamoeba (T4 genotype) isolates were recovered from corneal scrapes and contact lenses of patients with keratitis. Cloning and purification was performed for all isolate. Gram staining was performed to identify bacterial endosymbionts. DNA extraction, PCR, and nested PCR was set up to identify endosymbiont of amoeba. Evaluation of pathogenicity was conducted by osmo-tolerance and thermo-tolerance assays and cell culture, and then CPE (cytopathic effect) was survey. Statistical analysis was used between Acanthamoeba associated endosymbionts and Acanthamoeba without endosymbiont at 24, 48, 72, and 96 h. A p value < 0.05 was considered as significant, statistically. A total of 9 (60%) Acanthamoeba (T4 genotypes) isolates were successfully cloned for detecting microorganism endosymbionts. The only isolate negative for the presence of endosymbiont was ICS9. ICS7 (Pseudomonas aeruginosa, Aspergillus sp., and human adenovirus endosymbionts) and ICS2 (Escherichia coli endosymbiont) isolates were considered as Acanthamoeba associated endosymbionts. ICS7 and ICS2 isolates were highly pathogen whereas ICS9 isolate showed low pathogenicity in pathogenicity evaluated. Positive CPE for ICS7 and ICS2 isolates and negative CPE for ICS9 isolate were observed in cell culture. The average number of cells, trophozoites, and cysts among ICS7, ICS2, and ICS9 isolates at 24, 48, 72, and 96 h was significant. This is the first survey on microbial endosymbionts of Acanthamoeba in keratitis patients of Iran, and also the first report of Aspergillus sp, Achromobacter sp., Microbacterium sp., Brevibacillus sp, Brevundimonas sp and Mastadenovirus sp in Acanthamoeba as endosymbionts. Our study demonstrated that microbial endosymbionts can affect the pathogenicity of Acanthamoeba; however, further research is required to clarify the exact pattern of symbiosis, in order to modify treatment protocol.

RevDate: 2019-04-04

Naranjo E, Merfa MV, Ferreira V, et al (2019)

Liberibacter crescens biofilm formation in vitro: establishment of a model system for pathogenic 'Candidatus Liberibacter spp.'.

Scientific reports, 9(1):5150 pii:10.1038/s41598-019-41495-5.

The Liberibacter genus comprises insect endosymbiont bacterial species that cause destructive plant diseases, including Huanglongbing in citrus and zebra chip in potato. To date, pathogenic 'Candidatus Liberibacter spp.' (CLs) remain uncultured, therefore the plant-associated Liberibacter crescens (Lcr), only cultured species of the genus, has been used as a biological model for in vitro studies. Biofilm formation by CLs has been observed on the outer midgut surface of insect vectors, but not in planta. However, the role of biofilm formation in the life cycle of these pathogens remains unclear. Here, a model system for studying CLs biofilms was developed using Lcr. By culture media modifications, bovine serum albumin (BSA) was identified as blocking initial cell-surface adhesion. Removal of BSA allowed for the first time observation of Lcr biofilms. After media optimization for biofilm formation, we demonstrated that Lcr attaches to surfaces, and form cell aggregates embedded in a polysaccharide matrix both in batch cultures and under flow conditions in microfluidic chambers. Biofilm structures may represent excellent adaptive advantages for CLs during insect vector colonization helping with host retention, immune system evasion, and transmission. Future studies using the Lcr model established here will help in the understanding of the biology of CLs.

RevDate: 2019-04-06

Konecka E, Olszanowski Z, R Koczura (2019)

Wolbachia of phylogenetic supergroup E identified in oribatid mite Gustavia microcephala (Acari: Oribatida).

Molecular phylogenetics and evolution, 135:230-235 pii:S1055-7903(18)30535-9 [Epub ahead of print].

Heritable endosymbionts have been observed in arthropod and nematode hosts. The most-known among them is Wolbachia. Although the bacterium was previously identified in oribatid mites (Acari: Oribatida), it was not assigned to any phylogenetic group. Endosymbionts have a profound influence on their hosts, playing various functions that affect invertebrate's biology such as changing the way of reproduction. Oribatida provide the very unique examples of groups in which even whole families appear to be thelytokous, so we considered that it is worth to investigate the occurrence of endosymbiotic microorganisms in oribatid mites, especially that the knowledge on the symbionts occurrence in this invertebrate group is negligible. We report for the first time Wolbachia in oribatid mite Gustavia microcephala. The sequences of 16S rDNA, gltA, and ftsZ genes of the endosymbiont from the mite showed the highest similarity to Wolbachia found in Collembola. Phylogenetic analysis based on single gene and concatenated alignments of three genes revealed that the bacteria from G. microcephala and Collembola were related and clustered together with supergroup E. Relatively close relationship of Wolbachia from oribatid and collembolan hosts might mean at the evolutionary scale that horizontal transfer of bacteria between these two groups of invertebrates may take place.

RevDate: 2019-03-26

Guo J, Liu X, Poncelet N, et al (2019)

Detection and geographic distribution of seven facultative endosymbionts in two Rhopalosiphum aphid species.

MicrobiologyOpen [Epub ahead of print].

Study of the mutualistic associations between facultative symbionts and aphids are developed only in a few models. That survey on the situation and distribution of the symbionts in a certain area is helpful to obtain clues for the acquisition and spread of them as well as their roles played in host evolution. To understand the infection patterns of seven facultative symbionts (Serratia symbiotica, Hamiltonella defensa, Regiella insecticola, Rickettsia, Spiroplasma, Wolbachia, and Arsenophonus) in Rhopalosiphum padi (Linnaeus) and Rhopalosiphum maidis (Fitch), we collected 882 R. maidis samples (37 geographical populations) from China and 585 R. padi samples (32 geographical populations) from China and Europe. Results showed that both species were widely infected with various symbionts and totally 50.8% of R. maidis and 50.1% of R. padi were multi-infected with targeted symbionts. However, very few Rhopalosiphum aphids were infected with S. symbiotica. The infection frequencies of some symbionts were related to the latitude of collecting sites, suggesting the importance of environmental factors in shaping the geographic distribution of facultative symbionts. Also, R. maidis and R. padi were infected with different H. defensa strains based on phylogenetic analysis which may be determined by host ×symbiont genotype interactions. According to our results, the ubiquitous symbionts may play important roles in the evolution of their host aphid and their impacts on adaptation of R. padi and R. maidis were discussed as well.

RevDate: 2019-03-25

Uchi N, Fukudome M, Nozaki N, et al (2019)

Antimicrobial Activities of Cysteine-rich Peptides Specific to Bacteriocytes of the Pea Aphid Acyrthosiphon pisum.

Microbes and environments [Epub ahead of print].

Aphids have a mutualistic relationship with the bacterial endosymbiont Buchnera aphidicola. We previously reported seven cysteine-rich peptides in the pea aphid Acyrthosiphon pisum and named them Bacteriocyte-specific Cysteine-Rich (BCR) peptides; these peptides are exclusively expressed in bacteriocytes, special aphid cells that harbor symbionts. Similar symbiotic organ-specific cysteine-rich peptides identified in the root nodules of leguminous plants are named Nodule-specific Cysteine-Rich (NCR) peptides. NCR peptides target rhizobia in the nodules and are essential for symbiotic nitrogen fixation. A BacA (membrane protein) mutant of Sinorhizobium is sensitive to NCR peptides and is unable to establish symbiosis. Based on the structural and expressional similarities between BCR peptides and NCR peptides, we hypothesized that aphid BCR peptides exhibit antimicrobial activity, similar to some NCR peptides. We herein synthesized BCR peptides and investigated their antimicrobial activities and effects on the bacterial membrane of Escherichia coli. The peptides BCR1, BCR3, BCR5, and BCR8 exhibited antimicrobial activities with increased membrane permeability. An sbmA mutant of E. coli, a homolog of bacA of S. meliloti, was more sensitive to BCR peptides than the wild type. Our results suggest that BCR peptides have properties that may be required to control the endosymbiont, similar to NCR peptides in legumes.

RevDate: 2019-04-02

Kanakala S, M Ghanim (2019)

Global genetic diversity and geographical distribution of Bemisia tabaci and its bacterial endosymbionts.

PloS one, 14(3):e0213946 pii:PONE-D-18-36930.

Bemisia tabaci is one of the most threatening pests in agriculture, causing significant losses to many important crops on a global scale. The dramatic increase and availability of sequence data for B. tabaci species complex and its bacterial endosymbionts is critical for developing emerging sustainable pest management strategies which are based on pinpointing the global diversity of this important pest and its bacterial endosymbionts. To unravel the global genetic diversity of B. tabaci species complex focusing on its associated endosymbionts, along with Israeli whitefly populations collected in this study, we combined available sequences in databases, resulting in a total of 4,253 mitochondrial cytochrome oxidase I (mtCOI) sequences from 82 countries and 1,226 16S/23S rRNA endosymbiont sequences from 32 countries that were analyzed. Using Bayesian phylogenetic analysis, we identified two new B. tabaci groups within the species complex and described the global distribution of endosymbionts within this complex. Our analyses revealed complex divergence of the different endosymbiont sequences within the species complex, with overall one Hamiltonella, two Porteria (P1 and P2), two Arsenophonus (A1 and A2), two Wolbachia (super-groups O and B), four Cardinium (C1-C4) and three Rickettsia (R1-R3) groups were identified. Our comprehensive analysis provides an updated important resource for this globally important pest and its secondary symbionts, which have been a major subject for research in last three decades.

RevDate: 2019-03-17

Kohlmeier MG, White CE, Fowler JE, et al (2019)

Galactitol catabolism in Sinorhizobium meliloti is dependent on a chromosomally encoded sorbitol dehydrogenase and a pSymB-encoded operon necessary for tagatose catabolism.

Molecular genetics and genomics : MGG pii:10.1007/s00438-019-01545-z [Epub ahead of print].

The legume endosymbiont Sinorhizobium meliloti can utilize a broad range of carbon compounds to support its growth. The linear, six-carbon polyol galactitol is abundant in vascular plants and is metabolized in S. meliloti by the contribution of two loci SMb21372-SMb21377 and SMc01495-SMc01503 which are found on pSymB and the chromosome, respectively. The data suggest that several transport systems, including the chromosomal ATP-binding cassette (ABC) transporter smoEFGK, contribute to the uptake of galactitol, while the adjacent gene smoS encodes a protein for oxidation of galactitol into tagatose. Subsequently, genes SMb21374 and SMb21373, encode proteins that phosphorylate and epimerize tagatose into fructose-6-phosphate, which is further metabolized by the enzymes of the Entner-Doudoroff pathway. Of note, it was found that SMb21373, which was annotated as a 1,6-bis-phospho-aldolase, is homologous to the E. coli gene gatZ, which is annotated as encoding the non-catalytic subunit of a tagatose-1,6-bisphosphate aldolase heterodimer. When either of these genes was introduced into an Agrobacterium tumefaciens strain that carries a tagatose-6-phosphate epimerase mutation, they are capable of complementing the galactitol growth deficiency associated with this mutation, strongly suggesting that these genes are both epimerases. Phylogenetic analysis of the protein family (IPR012062) to which these enzymes belong, suggests that this misannotation is systemic throughout the family. S. meliloti galactitol catabolic mutants do not exhibit symbiotic deficiencies or the inability to compete for nodule occupancy.

RevDate: 2019-03-14

Taylor MJ, von Geldern TW, Ford L, et al (2019)

Preclinical development of an oral anti-Wolbachia macrolide drug for the treatment of lymphatic filariasis and onchocerciasis.

Science translational medicine, 11(483):.

There is an urgent global need for a safe macrofilaricide drug to accelerate elimination of the neglected tropical diseases onchocerciasis and lymphatic filariasis. From an anti-infective compound library, the macrolide veterinary antibiotic, tylosin A, was identified as a hit against Wolbachia This bacterial endosymbiont is required for filarial worm viability and fertility and is a validated target for macrofilaricidal drugs. Medicinal chemistry was undertaken to develop tylosin A analogs with improved oral bioavailability. Two analogs, A-1535469 and A-1574083, were selected. Their efficacy was tested against the gold-standard second-generation tetracycline antibiotics, doxycycline and minocycline, in mouse and gerbil infection models of lymphatic filariasis (Brugia malayi and Litomosoides sigmodontis) and onchocerciasis (Onchocerca ochengi). A 1- or 2-week course of oral A-1535469 or A-1574083 provided >90% Wolbachia depletion from nematodes in infected animals, resulting in a block in embryogenesis and depletion of microfilarial worm loads. The two analogs delivered comparative or superior efficacy compared to a 3- to 4-week course of doxycycline or minocycline. A-1574083 (now called ABBV-4083) was selected for further preclinical testing. Cardiovascular studies in dogs and toxicology studies in rats and dogs revealed no adverse effects at doses (50 mg/kg) that achieved plasma concentrations >10-fold above the efficacious concentration. A-1574083 (ABBV-4083) shows potential as an anti-Wolbachia macrolide with an efficacy, pharmacology, and safety profile that is compatible with a short-term oral drug course for treating lymphatic filariasis and onchocerciasis.

RevDate: 2019-03-13

Carter AC, Petersen CL, Wendt KL, et al (2019)

In Situ Ring Contraction and Transformation of the Rhizoxin Macrocycle through an Abiotic Pathway.

Journal of natural products [Epub ahead of print].

A Rhizopus sp. culture containing an endosymbiont partner (Burkholderia sp.) was obtained through a citizen-science-based soil-collection program. An extract prepared from the pair of organisms exhibited strong inhibition of Ewing sarcoma cells and was selected for bioassay-guided fractionation. This led to the purification of rhizoxin (1), a potent antimitotic agent that inhibited microtubule polymerization, along with several new (2-5) and known (6) analogues of 1. The structures of 2-6 were established using a combination of NMR data analysis, while the configurations of the new stereocenters were determined using ROESY spectroscopy and comparison of GIAO-derived and experimental data for NMR chemical shift and 3 JHH coupling values. Whereas compound 1 showed modest selectivity for Ewing sarcoma cell lines carrying the EWSR1/ FLI1 fusion gene, the other compounds were determined to be inactive. Chemically, compound 2 stands out from other rhizoxin analogues because it is the first member of this class that is reported to contain a one-carbon-smaller 15-membered macrolactone system. Through a combination of experimental and computational tests, we determined that 2 is likely formed via an acid-catalyzed Meinwald rearrangement from 1 because of the mild acidic culture environment created by the Rhizopus sp. isolate and its symbiont.

RevDate: 2019-04-15

Grisdale CJ, Smith DR, JM Archibald (2019)

Relative Mutation Rates in Nucleomorph-Bearing Algae.

Genome biology and evolution, 11(4):1045-1053.

Chlorarachniophyte and cryptophyte algae are unique among plastid-containing species in that they have a nucleomorph genome: a compact, highly reduced nuclear genome from a photosynthetic eukaryotic endosymbiont. Despite their independent origins, the nucleomorph genomes of these two lineages have similar genomic architectures, but little is known about the evolutionary pressures impacting nucleomorph DNA, particularly how their rates of evolution compare to those of the neighboring genetic compartments (the mitochondrion, plastid, and nucleus). Here, we use synonymous substitution rates to estimate relative mutation rates in the four genomes of nucleomorph-bearing algae. We show that the relative mutation rates of the host versus endosymbiont nuclear genomes are similar in both chlorarachniophytes and cryptophytes, despite the fact that nucleomorph gene sequences are notoriously highly divergent. There is some evidence, however, for slightly elevated mutation rates in the nucleomorph DNA of chlorarachniophytes-a feature not observed in that of cryptophytes. For both lineages, relative mutation rates in the plastid appear to be lower than those in the nucleus and nucleomorph (and, in one case, the mitochondrion), which is consistent with studies of other plastid-bearing protists. Given the divergent nature of nucleomorph genes, our finding of relatively low evolutionary rates in these genomes suggests that for both lineages a burst of evolutionary change and/or decreased selection pressures likely occurred early in the integration of the secondary endosymbiont.

RevDate: 2019-03-12

Brinker P, Fontaine MC, Beukeboom LW, et al (2019)

Host, Symbionts, and the Microbiome: The Missing Tripartite Interaction.

Trends in microbiology pii:S0966-842X(19)30040-X [Epub ahead of print].

Symbiosis between microbial associates and a host is a ubiquitous feature of life on earth, modulating host phenotypes. In addition to endosymbionts, organisms harbour a collection of host-associated microbes, the microbiome that can impact important host traits. In this opinion article we argue that the mutual influences of the microbiome and endosymbionts, as well as their combined influence on the host, are still understudied. Focusing on the endosymbiont Wolbachia, we present growing evidence indicating that host phenotypic effects are exerted in interaction with the remainder microbiome and the host. We thus advocate that only through an integrated approach that considers multiple interacting partners and environmental influences will we be able to gain a better understanding of host-microbe associations.

RevDate: 2019-03-29

Liu XD, Lei HX, FF Chen (2019)

Infection pattern and negative effects of a facultative endosymbiont on its insect host are environment-dependent.

Scientific reports, 9(1):4013 pii:10.1038/s41598-019-40607-5.

Regiella insecticola is a bacterial endosymbiont in insects that exhibits a negative effect on the fitness of hosts. Thus, it is not clear why this costly endosymbiont can persist in host populations. Here, we tested a hypothesis that the infection pattern and negative roles of the endosymbiont were not constant but environmentally dependent. The grain aphids Sitobion avenae, belonging to different genotypes and infected with Regiella or not, were used in this study. We found that S. avenae populations were infected with Regiella, Hamiltonella defensa, Serratia symbiotica and Rickettsia. The predominant endosymbionts in the aphid populations varied with season. Serratia and Rickettsia were predominant from December to February while Regiella predominated from March to May. The vertical transmission of Regiella was poorer at high temperature, but following conditioning for seven generations, the transmission rate improved. Regiella inhibited the production of winged aphids at 25 °C, but it did not affect winged morph production at the higher temperatures of 28 °C and 31 °C. Regiella infection decreased the intrinsic rate of increase (rm) of aphids at 25 °C and 28 °C. However, at 31 °C, the effect of Regiella on the rm varied depending on the aphid genotype and density. Thus, the negative effects of this endosymbiont on its host were environmentally dependent.

RevDate: 2019-03-09

Pons I, Renoz F, Noël C, et al (2019)

New Insights into the Nature of Symbiotic Associations in Aphids: Infection Process, Biological Effects and Transmission Mode of Cultivable Serratia symbiotica Bacteria.

Applied and environmental microbiology pii:AEM.02445-18 [Epub ahead of print].

Symbiotic microorganisms are widespread in nature and can play a major role in the ecology and evolution of animals. The aphid-Serratia symbiotica bacterium interaction provides a valuable model to study mechanisms behind these symbiotic associations. The recent discovery of cultivable S. symbiotica strains having the possibility of free-living lifestyle allowed us to simulate their environmental acquisition by aphids to examine the mechanisms involved in this infection pathway. Here, after oral ingestion, we analyzed the infection dynamic of cultivable S. symbiotica during the host's lifetime using qPCR and fluorescence techniques and determined the immediate fitness consequences of these bacteria on their new host. We further examined the transmission behavior and phylogenetic position of cultivable strains. Our study revealed that cultivable S. symbiotica are predisposed to establish a symbiotic association with new aphid host, settling in its gut. We showed that cultivable S. symbiotica colonized the entire aphid digestive tract following infection, after which the bacterium multiplied exponentially during aphid development. Our results further revealed that gut colonization by the bacteria induces a fitness cost to their hosts. Nevertheless, it appeared that the bacteria also offer an immediate protection against parasitoids. Interestingly, cultivable S. symbiotica strains seem to be extracellularly transmitted, possibly through the honeydew; while S. symbiotica is generally considered as a maternally-transmitted bacterium living within aphid body cavity and bringing some benefits to its hosts despite its costs. These findings provide new insights into the nature of symbiosis in aphids and the mechanisms underpinning these interactions.IMPORTANCES. symbiotica is one of the most common symbionts among aphid populations and includes a wide variety of strains whose degree of interdependence on the host may vary considerably. S. symbiotica strains with free-living capacity have recently been isolated from aphids. By using these strains, we established artificial associations by simulating new bacterial acquisitions involved in aphid gut infections to decipher their infection processes and biological effects on their new hosts. Our results showed the early stages involved in this route of infection. So far, S. symbiotica was considered as a maternally-transmitted aphid endosymbiont. Nevertheless, we showed that our cultivable S. symbiotica occupy and replicate in aphid gut and seem to be transmitted over generations through an environmental transmission mechanism. Moreover, cultivable S. symbiotica are both parasites and mutualists given the context, as many of aphid endosymbionts. Our findings give new perception of associations involved in bacterial mutualism in aphids.

RevDate: 2019-03-10

Lin D, Zhang L, Shao W, et al (2019)

Phylogenetic analyses and characteristics of the microbiomes from five mealybugs (Hemiptera: Pseudococcidae).

Ecology and evolution, 9(4):1972-1984 pii:ECE34889.

Associations between Sternorrhyncha insects and intracellular bacteria are common in nature. Mealybugs are destructive pests that seriously threaten the production of agriculture and forestry. Mealybugs have evolved intimate endosymbiotic relationships with bacteria, which provide them with essential amino acids, vitamins, and other nutrients. In this study, the divergence of five mealybugs was analyzed based up the sequences of the mitochondrial cytochrome oxidase I (mtCOI). Meanwhile, the distinct regions of the 16S rRNA gene of primary symbionts in the mealybugs were sequenced. Finally, high-throughput sequencing (HTS) techniques were used to study the microbial abundance and diversity in mealybugs. Molecular phylogenetic analyses revealed that these five mealybugs were subdivided into two different clusters. One cluster of mealybugs (Dysmicoccus neobrevipes, Pseudococcus comstocki, and Planococcus minor) harbored the primary endosymbiont "Candidatus Tremblaya princeps," and another cluster (Phenacoccus solenopsis and Phenacoccus solani) harbored "Ca. Tremblaya phenacola." The mtCOI sequence divergence between the two clusters was similar to the 16S rRNA sequence divergence between T. princeps and T. phenacola. Thus, we concluded that the symbiont phylogeny was largely concordant with the host phylogeny. The HTS showed that the microbial abundance and diversity within P. solani and P. solenopsis were highly similar, and there was lower overall species richness compared to the other mealybugs. Among the five mealybugs, we also found significant differences in Shannon diversity and observed species. These results provide a theoretical basis for further research on the coevolution of mealybugs and their symbiotic microorganisms. These findings are also useful for research on the effect of symbiont diversity on the pest status of mealybugs in agricultural systems.

RevDate: 2019-03-07

Thairu MW, AK Hansen (2019)

It's a small, small world: Unravelling the role and evolution of small RNAs in organelle and endosymbiont genomes.

FEMS microbiology letters pii:5371121 [Epub ahead of print].

Organelles and host-restricted bacterial symbionts are characterized by having highly reduced genomes that lack many key regulatory genes and elements. Thus, it has been hypothesized that the eukaryotic nuclear genome is primarily responsible for regulating these symbioses. However, with the discovery of organelle and symbiont expressed small RNAs (sRNAs) there is emerging evidence that these sRNAs may play a role in gene regulation as well. Here, we compare the diversity of organelle and bacterial symbiont sRNAs recently identified using genome-enabled '-omic' technologies and discuss their potential role in gene regulation. We also discuss how the genome architecture of small genomes may influence the evolution of these sRNAs and their potential function. Additionally, these new studies suggest that some sRNAs are conserved within organelle and symbiont taxa and respond to changes in the environment and/or their hosts. In summary, these results suggest that organelle and symbiont sRNAs may play a role in gene regulation in addition to nuclear-encoded host mechanisms.

RevDate: 2019-03-05

Zhang J, Dai Y, Fan S, et al (2019)

Association between extrauterine growth restriction and changes of intestinal flora in Chinese preterm infants.

Journal of developmental origins of health and disease pii:S2040174419000084 [Epub ahead of print].

The aim of the study was to investigate any association between extrauterine growth restriction (EUGR) and intestinal flora of <30-week-old preterm infants. A total of 59 preterm infants were assigned to EUGR (n=23) and non-EUGR (n=36) groups. Intestinal bacteria were compared by using high-throughput sequencing of bacterial rRNA. The total abundance of bacteria in 344 genera (7568 v. 13,760; P<0.0001) and 456 species (10,032 v. 18,240; P<0.0001) was significantly decreased in the EUGR group compared with the non-EUGR group. After application of a multivariate logistic model and adjusting for potential confounding factors, as well as false-discovery rate corrections, we found four bacterial genera with higher and one bacterial genus with lower abundance in the EUGR group compared with the control group. In addition, the EUGR group showed significantly increased abundances of six species (Streptococcus parasanguinis, Bacterium RB5FF6, two Klebsiella species and Microbacterium), but decreased frequencies of three species (one Acinetobacter species, Endosymbiont_of_Sphenophorus_lev and one Enterobacter_species) compared with the non-EUGR group. Taken together, there were significant changes in the intestinal microflora of preterm infants with EUGR compared to preterm infants without EUGR.

RevDate: 2019-04-09

Koehler L, Flemming FE, M Schrallhammer (2019)

Towards an ecological understanding of the killer trait - A reproducible protocol for testing its impact on freshwater ciliates.

European journal of protistology, 68:108-120.

Paramecium strains with the ability to kill other paramecia often harbour intracellular bacteria belonging to the genera Caedibacter or Caedimonas. Central structures of this killer trait are refractile bodies (R-bodies) produced by the endosymbionts. Once ingested by a sensitive Paramecium, R-bodies presumably act as delivery system for an unidentified toxin which causes the death of endosymbiont-free paramecia while those infected gain resistance from their symbionts. The killer trait is therefore considered as competitive advantage for the hosts of R-body producers. While its effectiveness against paramecia is well documented, the effects on other aquatic ciliates are much less studied. In order to address the broadness of the killer trait, a reproducible killer test assay considering the effects on predatory ciliates (Climacostomum virens and Dileptus jonesi) as well as potential bacterivorous Paramecium competitors (Dexiostoma campyla, Euplotes aediculatus, Euplotes woodruffi, and Spirostomum teres) as possibly susceptible species was established. All used organisms were molecularly characterized to increase traceability and reproducibility. The absence of any lethal effects in both predators and competitors after exposure to killer paramecia strongly suggests a narrow action range for the killer trait. Thus, R-body producing bacteria provide their host with a complex, costly strategy to outcompete symbiont-free congeners only.

RevDate: 2019-03-02

Gil R, A Latorre (2019)

Unity Makes Strength: A Review on Mutualistic Symbiosis in Representative Insect Clades.

Life (Basel, Switzerland), 9(1): pii:life9010021.

Settled on the foundations laid by zoologists and embryologists more than a century ago, the study of symbiosis between prokaryotes and eukaryotes is an expanding field. In this review, we present several models of insect⁻bacteria symbioses that allow for the detangling of most known features of this distinctive way of living, using a combination of very diverse screening approaches, including molecular, microscopic, and genomic techniques. With the increasing the amount of endosymbiotic bacteria genomes available, it has been possible to develop evolutionary models explaining the changes undergone by these bacteria in their adaptation to the intracellular host environment. The establishment of a given symbiotic system can be a root cause of substantial changes in the partners' way of life. Furthermore, symbiont replacement and/or the establishment of bacterial consortia are two ways in which the host can exploit its interaction with environmental bacteria for endosymbiotic reinvigoration. The detailed study of diverse and complex symbiotic systems has revealed a great variety of possible final genomic products, frequently below the limit considered compatible with cellular life, and sometimes with unanticipated genomic and population characteristics, raising new questions that need to be addressed in the near future through a wider exploration of new models and empirical observations.

RevDate: 2019-03-01

Onder Z, Ciloglu A, Duzlu O, et al (2019)

Molecular detection and identification of Wolbachia endosymbiont in fleas (Insecta: Siphonaptera).

Folia microbiologica pii:10.1007/s12223-019-00692-5 [Epub ahead of print].

The aim of this study was to determine the presence and prevalence of Wolbachia bacteria in natural population of fleas (Insecta: Siphonaptera) in Turkey, and to exhibit the molecular characterization and the phylogenetic reconstruction at the positive isolates with other species in GenBank, based on 16S rDNA sequences. One hundred twenty-four flea samples belonging to the species Ctenocephalides canis, C. felis, and Pulex irritans were collected from animal shelters in Kayseri between January and August 2017. All flea species were individually screened for the presence of Wolbachia spp. by polymerase chain reaction (PCR) targeting the 16S ribosomal RNA gene. According to PCR analyses, Wolbachia spp. were found prevalent in C. canis and P. irritans fleas, while it was not detected in the C. felis species. Totally, 20 isolates were purified from agarose gel and sequenced with the same primers for molecular characterization and phylogenetic analyses. The sequence analyses revealed 17 polymorphic sites and 2 genetically different Wolbachia isolates, representing two different haplotypes in two flea species. The distribution patterns, molecular characterization, and phylogenetic status of Wolbachia spp. of fleas in Turkey are presented for the first time with this study. Understanding of the role of Wolbachia in vector biology may provide information for developing Wolbachia-based biological control tools.

RevDate: 2019-03-29

Maire J, Vincent-Monégat C, Balmand S, et al (2019)

Weevil pgrp-lb prevents endosymbiont TCT dissemination and chronic host systemic immune activation.

Proceedings of the National Academy of Sciences of the United States of America, 116(12):5623-5632.

Long-term intracellular symbiosis (or endosymbiosis) is widely distributed across invertebrates and is recognized as a major driving force in evolution. However, the maintenance of immune homeostasis in organisms chronically infected with mutualistic bacteria is a challenging task, and little is known about the molecular processes that limit endosymbiont immunogenicity and host inflammation. Here, we investigated peptidoglycan recognition protein (PGRP)-encoding genes in the cereal weevil Sitophilus zeamais's association with Sodalis pierantonius endosymbiont. We discovered that weevil pgrp-lb generates three transcripts via alternative splicing and differential regulation. A secreted isoform is expressed in insect tissues under pathogenic conditions through activation of the PGRP-LC receptor of the immune deficiency pathway. In addition, cytosolic and transmembrane isoforms are permanently produced within endosymbiont-bearing organ, the bacteriome, in a PGRP-LC-independent manner. Bacteriome isoforms specifically cleave the tracheal cytotoxin (TCT), a peptidoglycan monomer released by endosymbionts. pgrp-lb silencing by RNAi results in TCT escape from the bacteriome to other insect tissues, where it chronically activates the host systemic immunity through PGRP-LC. While such immune deregulations did not impact endosymbiont load, they did negatively affect host physiology, as attested by a diminished sexual maturation of adult weevils. Whereas pgrp-lb was first described in pathogenic interactions, this work shows that, in an endosymbiosis context, specific bacteriome isoforms have evolved, allowing endosymbiont TCT scavenging and preventing chronic endosymbiont-induced immune responses, thus promoting host homeostasis.

RevDate: 2019-03-29

Bykov RА, Yudina MA, Gruntenko NE, et al (2019)

Prevalence and genetic diversity of Wolbachia endosymbiont and mtDNA in Palearctic populations of Drosophila melanogaster.

BMC evolutionary biology, 19(Suppl 1):48 pii:10.1186/s12862-019-1372-9.

BACKGROUND: Maternally inherited Wolbachia symbionts infect D. melanogaster populations worldwide. Infection rates vary greatly. Genetic diversity of Wolbachia in D. melanogaster can be subdivided into several closely related genotypes coinherited with certain mtDNA lineages. mtDNA haplotypes have the following global distribution pattern: mtDNA clade I is mostly found in North America, II and IV in Africa, III in Europe and Africa, V in Eurasia, VI is global but very rare, and VIII is found in Asia. The wMel Wolbachia genotype is predominant in D. melanogaster populations. However, according to the hypothesis of global Wolbachia replacement, the wMelCS genotype was predominant before the XX century when it was replaced by the wMel genotype. Here we analyse over 1500 fly isolates from the Palearctic region to evaluate the prevalence, genetic diversity and distribution pattrern of the Wolbachia symbiont, occurrence of mtDNA variants, and finally to discuss the Wolbachia genotype global replacement hypothesis.

RESULTS: All studied Palearctic populations of D. melanogaster were infected with Wolbachia at a rate of 33-100%. We did not observe any significant correlation between infection rate and longitude or latitude. Five previously reported Wolbachia genotypes were found in Palearctic populations with a predominance of the wMel variant. The mtDNA haplotypes of the I_II_III clade and V clade were prevalent in Palearctic populations. To test the recent Wolbachia genotype replacement hypothesis, we examined three genomic regions of CS-like genotypes. Low genetic diversity was observed, only two haplotypes of the CS genotypes with a 'CCG' variant predominance were found.

CONCLUSION: The results of our survey of Wolbachia infection prevalence and genotype diversity in Palearctic D. melanogaster populations confirm previous studies. Wolbachia is ubiquitous in the Palearctic region. The wMel genotype is dominant with local occurrence of rare genotypes. Together with variants of the V mtDNA clade, the variants of the 'III+' clade are dominant in both infected and uninfected flies of Palearctic populations. Based on our data on Wolbachia and mtDNA in different years in some Palearctic localities, we can conclude that flies that survive the winter make the predominant symbiont contribution to the subsequent generation. A comprehensive overview of mtDNA and Wolbachia infection of D. melanogaster populations worldwide does not support the recent global Wolbachia genotype replacement hypothesis. However, we cannot exclude wMelCS genotype rate fluctuations in the past.

RevDate: 2019-02-24

Singhal K, S Mohanty (2019)

Genome organisation and comparative genomics of four novel Wolbachia genome assemblies from Indian Drosophila host.

Functional & integrative genomics pii:10.1007/s10142-019-00664-5 [Epub ahead of print].

Wolbachia has long been known to share an endosymbiotic relationship with its host as an obligate intracellular organism. Wolbachia diversity as different supergroups is found to be host-specific in most cases except a few, where the host species is seen to accommodate multiple strains. Besides, the Wolbachia genome must have undergone several changes in response to the evolving host genome in order to adapt and establish a strong association with its host, thus making a distinctive Wolbachia-host alliance. The present study focusses on four novel genome assembly and genome-wide sequence variations of Indian Wolbachia strains, i.e. wMel and wRi isolated from two different Drosophila hosts. The genome assembly has an average size of ~ 1.1 Mb and contains ~ 1100 genes, which is comparable with the previously sequenced Wolbachia genomes. The comparative genomics analysis of these genomes and sequence-wide comparison of some functionally significant genes, i.e. ankyrin repeats, Wsp and T4SS, highlight their sequence similarities and dissimilarities, further supporting the strain-specific association of Wolbachia to its host. Interestingly, some of the sequence variations are also found to be restricted to only Indian Wolbachia strains. Further analysis of prophage and their flanking regions in the Wolbachia genome reveals the presence of several functional genes which may assist the phage to reside inside the bacterial host, thus providing a trade-off for the endosymbiont-host association. Understanding this endosymbiont genome in different eco-geographical conditions has become imperative for the recent use of Wolbachia in medical entomology as a vector-control agent.

RevDate: 2019-02-27

Lhee D, Ha JS, Kim S, et al (2019)

Evolutionary dynamics of the chromatophore genome in three photosynthetic Paulinella species.

Scientific reports, 9(1):2560 pii:10.1038/s41598-019-38621-8.

The thecate amoeba Paulinella is a valuable model for understanding plastid organellogenesis because this lineage has independently gained plastids (termed chromatophores) of alpha-cyanobacterial provenance. Plastid primary endosymbiosis in Paulinella occurred relatively recently (90-140 million years ago, Mya), whereas the origin of the canonical Archaeplastida plastid occurred >1,500 Mya. Therefore, these two events provide independent perspectives on plastid formation on vastly different timescales. Here we generated the complete chromatophore genome sequence from P. longichromatophora (979,356 bp, GC-content = 38.8%, 915 predicted genes) and P. micropora NZ27 (977,190 bp, GC-content = 39.9%, 911 predicted genes) and compared these data to that from existing chromatophore genomes. Our analysis suggests that when a basal split occurred among photosynthetic Paulinella species ca. 60 Mya, only 35% of the ancestral orthologous gene families from the cyanobacterial endosymbiont remained in chromatophore DNA. Following major gene losses during the early stages of endosymbiosis, this process slowed down significantly, resulting in a conserved gene content across extant taxa. Chromatophore genes faced relaxed selection when compared to homologs in free-living alpha-cyanobacteria, likely reflecting the homogeneous intracellular environment of the Paulinella host. Comparison of nucleotide substitution and insertion/deletion events among different P. micropora strains demonstrates that increases in AT-content and genome reduction are ongoing and dynamic processes in chromatophore evolution.

RevDate: 2019-03-03

Garcia-Arraez MG, Masson F, Escobar JCP, et al (2019)

Functional analysis of RIP toxins from the Drosophila endosymbiont Spiroplasma poulsonii.

BMC microbiology, 19(1):46 pii:10.1186/s12866-019-1410-1.

BACKGROUND: Insects frequently live in close relationship with symbiotic bacteria that carry out beneficial functions for their host, like protection against parasites and viruses. However, in some cases, the mutualistic nature of such associations is put into question because of detrimental phenotypes caused by the symbiont. One example is the association between the vertically transmitted facultative endosymbiont Spiroplasma poulsonii and its natural host Drosophila melanogaster. Whereas S. poulsonii protects its host against parasitoid wasps and nematodes by the action of toxins from the family of Ribosome Inactivating Proteins (RIPs), the presence of S. poulsonii has been reported to reduce host's life span and to kill male embryos by a toxin called Spaid. In this work, we investigate the harmful effects of Spiroplasma RIPs on Drosophila in the absence of parasite infection.

RESULTS: We show that only two Spiroplasma RIPs (SpRIP1 and SpRIP2) among the five RIP genes encoded in the S. poulsonii genome are significantly expressed during the whole Drosophila life cycle. Heterologous expression of SpRIP1 and 2 in uninfected flies confirms their toxicity, as indicated by a reduction of Drosophila lifespan and hemocyte number. We also show that RIPs can cause the death of some embryos, including females.

CONCLUSION: Our results indicate that RIPs released by S. poulsonii contribute to the reduction of host lifespan and embryo mortality. This suggests that SpRIPs may impact the insect-symbiont homeostasis beyond their protective function against parasites.

RevDate: 2019-02-14

Martínez-Rodríguez P, Rolán-Alvarez E, Del Mar Pérez-Ruiz M, et al (2019)

Geographic and Temporal Variation of Distinct Intracellular Endosymbiont Strains of Wolbachia sp. in the Grasshopper Chorthippus parallelus: a Frequency-Dependent Mechanism?.

Microbial ecology pii:10.1007/s00248-019-01338-2 [Epub ahead of print].

Wolbachia is an intracellular endosymbiont that can produce a range of effects on host fitness, but the temporal dynamics of Wolbachia strains have rarely been experimentally evaluated. We compare interannual strain frequencies along a geographical region for understanding the forces that shape Wolbachia strain frequency in natural populations of its host, Chorthippus parallelus (Orthoptera, Acrididae). General linear models show that strain frequency changes significantly across geographical and temporal scales. Computer simulation allows to reject the compatibility of the observed patterns with either genetic drift or sampling errors. We use consecutive years to estimate total Wolbachia strain fitness. Our estimation of Wolbachia fitness is significant in most cases, within locality and between consecutive years, following a negatively frequency-dependent trend. Wolbachia spp. B and F strains show a temporal pattern of variation that is compatible with a negative frequency-dependent natural selection mechanism. Our results suggest that such a mechanism should be at least considered in future experimental and theoretical research strategies that attempt to understand Wolbachia biodiversity.

RevDate: 2019-04-11

Binetruy F, Bailly X, Chevillon C, et al (2019)

Phylogenetics of the Spiroplasma ixodetis endosymbiont reveals past transfers between ticks and other arthropods.

Ticks and tick-borne diseases, 10(3):575-584.

The bacterium Spiroplasma ixodetis is a maternally inherited endosymbiont primarily described from ticks but also found widespread across other arthropods. While it has been identified as a male-killing agent in some insect species, the consequences of infection with S. ixodetis in ticks are entirely unknown, and it is unclear how this endosymbiont spreads across tick species. Here, we have investigated this aspect through the examination of the diversity and evolutionary history of S. ixodetis infections in 12 tick species and 12 other arthropod species. Using a multi-locus typing approach, we identified that ticks harbor a substantial diversity of divergent S. ixodetis strains. Phylogenetic investigations revealed that these S. ixodetis strains do not cluster within a tick-specific subclade but rather exhibit distinct evolutionary origins. In their past, these strains have undergone repeated horizontal transfers between ticks and other arthropods, including aphids and flies. This diversity pattern strongly suggests that maternal inheritance and horizontal transfers are key drivers of S. ixodetis spread, dictating global incidence of infections across tick communities. We do not, however, detect evidence of S. ixodetis-based male-killing since we observed that infections were widely present in both males and females across populations of the African blue tick Rhipicephalus decoloratus.

RevDate: 2019-02-12

Augustinos AA, Moraiti CA, Drosopoulou E, et al (2019)

Old residents and new arrivals of Rhagoletis species in Europe.

Bulletin of entomological research pii:S0007485319000063 [Epub ahead of print].

The genus Rhagoletis (Diptera: Tephritidae) comprises more than 65 species distributed throughout Europe, Asia and America, including many species of high economic importance. Currently, there are three Rhagoletis species that infest fruits and nuts in Europe. The European cherry fruit fly, Rhagoletis cerasi (may have invaded Europe a long time ago from the Caucasian area of West Asia), and two invasive species (recently introduced from North America): the eastern American cherry fruit fly, R. cingulata, and the walnut husk fly, R. completa. The presence of different Rhagoletis species may enhance population dynamics and establish an unpredictable economic risk for several fruit and nut crops in Europe. Despite their excessive economic importance, little is known on population dynamics, genetics and symbiotic associations for making sound pest control decisions in terms of species-specific, environmental friendly pest control methods. To this end, the current paper (a) summarizes recently accumulated genetic and population data for the European Rhagoletis species and their association with the endosymbiont Wolbachia pipientis, and (b) explores the possibility of using the current knowledge for implementing the innovative biological control methods of sterile insect technique and incompatible insect technique.

RevDate: 2019-02-13

Gruber A (2019)

What's in a name? How organelles of endosymbiotic origin can be distinguished from endosymbionts.

Microbial cell (Graz, Austria), 6(2):123-133 pii:MIC0178E151.

Mitochondria and plastids evolved from free-living bacteria, but are now considered integral parts of the eukaryotic species in which they live. Therefore, they are implicitly called by the same eukaryotic species name. Historically, mitochondria and plastids were known as "organelles", even before their bacterial origin became fully established. However, since organelle evolution by endosymbiosis has become an established theory in biology, more and more endosymbiotic systems have been discovered that show various levels of host/symbiont integration. In this context, the distinction between "host/symbiont" and "eukaryote/organelle" systems is currently unclear. The criteria that are commonly considered are genetic integration (via gene transfer from the endosymbiont to the nucleus), cellular integration (synchronization of the cell cycles), and metabolic integration (the mutual dependency of the metabolisms). Here, I suggest that these criteria should be evaluated according to the resulting coupling of genetic recombination between individuals and congruence of effective population sizes, which determines if independent speciation is possible for either of the partners. I would like to call this aspect of integration "sexual symbiont integration". If the partners lose their independence in speciation, I think that they should be considered one species. The partner who maintains its genetic recombination mechanisms and life cycle should then be the name giving "host"; the other one would be the organelle. Distinguishing between organelles and symbionts according to their sexual symbiont integration is independent of any particular mechanism or structural property of the endosymbiont/host system under investigation.

RevDate: 2019-02-12

Vujanovic V, Kim SH, Lahlali R, et al (2019)

Spectroscopy and SEM imaging reveal endosymbiont-dependent components changes in germinating kernel through direct and indirect coleorhiza-fungus interactions under stress.

Scientific reports, 9(1):1665 pii:10.1038/s41598-018-36621-8.

In the present study, FTIR spectroscopy and hyperspectral imaging was introduced as a non-destructive, sensitive-reliable tool for assessing the tripartite kernel-fungal endophyte environment interaction. Composition of coleorhizae of Triticum durum was studied under ambient and drought stress conditions. The OH-stretch IR absorption spectrum suggests that the water-deficit was possibly improved or moderated by kernel's endophytic partner. The OH-stretch frequency pattern coincides with other (growth and stress) related molecular changes. Analysis of lipid (3100-2800 cm-1) and protein (1700-1550 cm-1) regions seems to demonstrate that drought has a positive impact on lipids. The fungal endosymbiont direct contact with kernel during germination had highest effect on both lipid and protein (Amide I and II) groups, indicating an increased stress resistance in inoculated kernel. Compared to the indirect kernel-fungus interaction and to non-treated kernels (control), direct interaction produced highest effect on lipids. Among treatments, the fingerprint region (1800-800 cm-1) and SEM images indicated an important shift in glucose oligosaccharides, possibly linked to coleorhiza-polymer layer disappearance. Acquired differentiation in coleorhiza composition of T. durum, between ambient and drought conditions, suggests that FTIR spectroscopy could be a promising tool for studying endosymbiont-plant interactions within a changing environment.

RevDate: 2019-02-19

Kampfraath AA, Klasson L, Anvar SY, et al (2019)

Genome expansion of an obligate parthenogenesis-associated Wolbachia poses an exception to the symbiont reduction model.

BMC genomics, 20(1):106 pii:10.1186/s12864-019-5492-9.

BACKGROUND: Theory predicts that dependency within host-endosymbiont interactions results in endosymbiont genome size reduction. Unexpectedly, the largest Wolbachia genome was found in the obligate, parthenogenesis-associated wFol. In this study, we investigate possible processes underlying this genome expansion by comparing a re-annotated wFol genome to other Wolbachia genomes. In addition, we also search for candidate genes related to parthenogenesis induction (PI).

RESULTS: Within wFol, we found five phage WO regions representing 25.4% of the complete genome, few pseudogenized genes, and an expansion of DNA-repair genes in comparison to other Wolbachia. These signs of genome conservation were mirrored in the wFol host, the springtail F. candida, which also had an expanded DNA-repair gene family and many horizontally transferred genes. Across all Wolbachia genomes, there was a strong correlation between gene numbers of Wolbachia strains and their hosts. In order to identify genes with a potential link to PI, we assembled the genome of an additional PI strain, wLcla. Comparisons between four PI Wolbachia, including wFol and wLcla, and fourteen non-PI Wolbachia yielded a small set of potential candidate genes for further investigation.

CONCLUSIONS: The strong similarities in genome content of wFol and its host, as well as the correlation between host and Wolbachia gene numbers suggest that there may be some form of convergent evolution between endosymbiont and host genomes. If such convergent evolution would be strong enough to overcome the evolutionary forces causing genome reduction, it would enable expanded genomes within long-term obligate endosymbionts.

RevDate: 2019-02-07

Lanzoni O, Sabaneyeva E, Modeo L, et al (2019)

Diversity and environmental distribution of the cosmopolitan endosymbiont "Candidatus Megaira".

Scientific reports, 9(1):1179 pii:10.1038/s41598-018-37629-w.

Members of the order Rickettsiales are often found in association with ciliated protists. An interesting case is the bacterial endosymbiont "Candidatus Megaira", which is phylogenetically closely related to the pathogen Rickettsia. "Candidatus Megaira" was first described as an intracellular bacterium in several ciliate species. Since then it has been found in association with diverse evolutionary distantly-related hosts, among them other unicellular eukaryotes, and also algae, and metazoa, such as cnidarians. We provide the characterization of several new strains of the type species "Candidatus Megaira polyxenophila", and the multidisciplinary description of a novel species, "Candidatus Megaira venefica", presenting peculiar features, which highlight the diversity and variability of these widespread bacterial endosymbionts. Screening of the 16S rRNA gene short amplicon database and phylogenetic analysis of 16S rRNA gene hypervariable regions revealed the presence of further hidden lineages, and provided hints on the possibility that these bacteria may be horizontally transmitted among aquatic protists and metazoa. The phylogenetic reconstruction supports the existence of at least five different separate species-level clades of "Candidatus Megaira", and we designed a set of specific probes allowing easy recognition of the four major clades of the genus.

RevDate: 2019-02-19

Piquet B, Shillito B, Lallier FH, et al (2019)

High rates of apoptosis visualized in the symbiont-bearing gills of deep-sea Bathymodiolus mussels.

PloS one, 14(2):e0211499 pii:PONE-D-18-27785.

Symbiosis between Bathymodiolus and Gammaproteobacteria allows these deep-sea mussels to live in toxic environments such as hydrothermal vents and cold seeps. The quantity of endosymbionts within the gill-bacteriocytes appears to vary according to the hosts environment; however, the mechanisms of endosymbiont population size regulation remain obscure. We investigated the possibility of a control of endosymbiont density by apoptosis, a programmed cell death, in three mussel species. Fluorometric TUNEL and active Caspase-3-targeting antibodies were used to visualize and quantify apoptotic cells in mussel gills. To control for potential artefacts due to depressurization upon specimen recovery from the deep-sea, the apoptotic rates between mussels recovered unpressurised, versus mussels recovered in a pressure-maintaining device, were compared in two species from hydrothermal vents on the Mid-Atlantic Ridge: Bathymodiolus azoricus and B. puteoserpentis. Results show that pressurized recovery had no significant effect on the apoptotic rate in the gill filaments. Apoptotic levels were highest in the ciliated zone and in the circulating hemocytes, compared to the bacteriocyte zone. Apoptotic gill-cells in B. aff. boomerang from cold seeps off the Gulf of Guinea show similar distribution patterns. Deep-sea symbiotic mussels have much higher rates of apoptosis in their gills than the coastal mussel Mytilus edulis, which lacks chemolithoautotrophic symbionts. We discuss how apoptosis might be one of the mechanisms that contribute to the adaptation of deep-sea mussels to toxic environments and/or to symbiosis.

RevDate: 2019-04-11

Sinha A, Li Z, Sun L, et al (2019)

Complete Genome Sequence of the Wolbachia wAlbB Endosymbiont of Aedes albopictus.

Genome biology and evolution, 11(3):706-720.

Wolbachia, an alpha-proteobacterium closely related to Rickettsia, is a maternally transmitted, intracellular symbiont of arthropods and nematodes. Aedes albopictus mosquitoes are naturally infected with Wolbachia strains wAlbA and wAlbB. Cell line Aa23 established from Ae. albopictus embryos retains only wAlbB and is a key model to study host-endosymbiont interactions. We have assembled the complete circular genome of wAlbB from the Aa23 cell line using long-read PacBio sequencing at 500× median coverage. The assembled circular chromosome is 1.48 megabases in size, an increase of more than 300 kb over the published draft wAlbB genome. The annotation of the genome identified 1,205 protein coding genes, 34 tRNA, 3 rRNA, 1 tmRNA, and 3 other ncRNA loci. The long reads enabled sequencing over complex repeat regions which are difficult to resolve with short-read sequencing. Thirteen percent of the genome comprised insertion sequence elements distributed throughout the genome, some of which cause pseudogenization. Prophage WO genes encoding some essential components of phage particle assembly are missing, while the remainder are found in five prophage regions/WO-like islands or scattered around the genome. Orthology analysis identified a core proteome of 535 orthogroups across all completed Wolbachia genomes. The majority of proteins could be annotated using Pfam and eggNOG analyses, including ankyrins and components of the Type IV secretion system. KEGG analysis revealed the absence of five genes in wAlbB which are present in other Wolbachia. The availability of a complete circular chromosome from wAlbB will enable further biochemical, molecular, and genetic analyses on this strain and related Wolbachia.

RevDate: 2019-02-06

Lavy O, Gophna U, Gefen E, et al (2018)

The Effect of Density-Dependent Phase on the Locust Gut Bacterial Composition.

Frontiers in microbiology, 9:3020.

The desert locust demonstrates density-dependent phase polyphenism: For extended periods it appears in a non-aggregating, non-migrating phenotype, known as the solitary phase. When circumstances change, solitary individuals may aggregate and transform to the gregarious phenotype, which have a strong propensity for generating large swarms. Previous reports have suggested a role for gut-bacteria derived volatiles in the swarming phenomenon, and suggested that locusts are capable of manipulating their gut microbiome according to their density-dependent phases. Here, we directly tested this hypothesis for the first time. Using locusts of both phases from well-controlled laboratory cultures as well as gregarious field-collected individuals; and high-throughput sequencing. We characterized the hindgut bacterial community composition in the two phases of the desert locust. Our findings demonstrate that laboratory-reared gregarious and solitary locusts maintain a stable core of Enterobacter. However, while different generations of gregarious locust experience shifts in their Enterobacter's relative abundance; the solitary locusts maintain a stable gut microbiome, highly similar to that of the field-collected locusts. Tentative phase differences in wild populations' microbiome may thus be an indirect effect of environmental or other factors that push the swarming individuals to homogenous gut bacteria. We therefore conclude that there are phase-related differences in the population dynamics of the locust hindgut bacterial composition, but there is no intrinsic density-dependent mechanism directly affecting the gut microbiome.

RevDate: 2019-02-01

Epstein HE, Torda G, Munday PL, et al (2019)

Parental and early life stage environments drive establishment of bacterial and dinoflagellate communities in a common coral.

The ISME journal pii:10.1038/s41396-019-0358-3 [Epub ahead of print].

The establishment of coral microbial communities in early developmental stages is fundamental to coral fitness, but its drivers are largely unknown, particularly for bacteria. Using an in situ reciprocal transplant experiment, we examined the influence of parental, planulation and early recruit environments on the microbiome of brooded offspring in the coral Pocillopora damicornis. 16S rRNA and ITS2 rDNA gene metabarcoding showed that bacterial and microalgal endosymbiont communities varied according to parental and planulation environments, but not with early recruit environment. Only a small number of bacterial strains were shared between offspring and their respective parents, revealing bacterial establishment as largely environmentally driven in very early life stages. Conversely, microalgal communities of recruits were highly similar to those of their respective parents, but also contained additional low abundance strains, suggesting both vertical transmission and novel ('horizontal') acquisition. Altogether, recruits harboured more variable microbiomes compared to their parents, indicating winnowing occurs as corals mature.

RevDate: 2019-04-10

Moreira M, Aguiar AMF, Bourtzis K, et al (2019)

Wolbachia (Alphaproteobacteria: Rickettsiales) Infections in Isolated Aphid Populations from Oceanic Islands of the Azores Archipelago: Revisiting the Supergroups M and N.

Environmental entomology, 48(2):326-334.

Aphids (Hemiptera: Aphididae) have provided a suitable model to study endosymbionts, their community, and dynamics since the discovery of the obligate endosymbiont Buchnera aphidicola in these organisms. In previous studies, Wolbachia was found in some aphid species. In the present study, we report the prevalence of Wolbachia in aphids sampled from a geographically isolated region (Azores Islands), aiming at a better understanding and characterization of the two newly reported supergroups, M and N. The description of the supergroup M was based on 16S rRNA as well as some protein-coding genes. However, the assignment of the supergroup N was according to 16S rRNA gene sequences of a very few samples. We collected aphid samples and performed phylogenetic analysis of 16S rRNA gene as well as four protein-coding genes (gatB, ftsZ, coxA, and hcpA). The results demonstrate that the 16S rRNA gene data can unambiguously assign the strain supergroup and that the two supergroups, N and M, are equally prevalent in Azorean aphids. The available sequence data for the protein-coding markers can identify supergroup M but the status of supergroup N is inconclusive, requiring further studies. The data suggest that horizontal transmission of Wolbachia (Hertig and Wolbach) between two phylogenetically distant aphid species cohabiting the same plant host.

RevDate: 2019-02-15

Adhav A, Harne S, Bhide A, et al (2019)

Mechanistic insights into enzymatic catalysis by trehalase from the insect gut endosymbiont Enterobacter cloacae.

The FEBS journal [Epub ahead of print].

Energy metabolism in the diamondback moth Plutella xylostella is facilitated by trehalase, an enzyme which assists in trehalose hydrolysis, from the predominant gut bacterium Enterobacter cloacae. We report the biochemical and structural characterization of recombinant trehalase from E. cloacae (Px_EclTre). Px_EclTre showed KM of 1.47 (±0.05) mm, kcat of 6254.72 min-1 and Vmax 0.2 (±0.002) mm·min-1 at 55 °C and acidic pH. Crystal structures of Px_EclTre were determined in the ligand-free form and bound to the inhibitor Validoxylamine A. The crystal structure of the ligand-free form, unavailable until now for any other bacterial trehalases, enabled us to delineate the conformational changes accompanying ligand binding in trehalases. Multiple salt bridges were identified that potentially facilitated closure of a hood over the substrate-binding site. A cluster of five tryptophans lined the -1 substrate-binding subsite, interacted with crucial active site residues and contributed to both trehalase activity and stability. The importance of these residues in enzyme activity was further validated by mutagenesis studies. Many of these identified residues form part of signature motifs and other conserved sequences in trehalases. The structure analysis thus led to the assignment of the functional role to these conserved residues. This information can be further explored for the design of effective inhibitors against trehalases.

RevDate: 2019-01-23
CmpDate: 2019-01-23

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: 2019-03-21
CmpDate: 2019-03-21

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, 11(2):362-379 pii:5284916.

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 harbor bacterial endosymbionts representing a novel genus, Candidatus Phycorickettsia, and an operon of unclear function (ebo) obtained by horizontal gene transfer 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 horizontal gene transfer 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: 2019-02-15
CmpDate: 2019-02-14

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.

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 Ae. 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: 2019-01-10

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: 2019-03-15

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.), 9(3):709-717 pii:g3.118.200763.

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 ccmB with the highest density of RNA editing sites (53.7 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: 2019-03-25
CmpDate: 2019-03-25

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, 116(4):1414-1419.

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: 2019-02-28
CmpDate: 2019-02-28

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, 77(2):537-545.

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: 2019-04-08
CmpDate: 2019-04-08

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: 2019-02-15
CmpDate: 2019-02-13

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: 2019-04-05
CmpDate: 2019-04-05

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: 2019-01-14

Gangwar M, Jha R, Goyal M, et al (2019)

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

Vaccine, 37(4):571-580.

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: 2018-12-26

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: 2019-04-11
CmpDate: 2019-04-11

Manzello DP, Matz MV, Enochs IC, et al (2019)

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, 25(3):1016-1031.

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 nonbleached 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.

RevDate: 2018-12-20

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: 2018-12-19

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: 2019-03-04

Altamia MA, Shipway JR, Concepcion GP, et al (2019)

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, 69(3):638-644.

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: 2019-04-11

Crowell RM, Nienow JA, AB Cahoon (2019)

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, 55(2):352-364.

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% pair-wise 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 Durinskia baltica's endosymbiont.

RevDate: 2019-03-21

Qi LD, Sun JT, Hong XY, et al (2019)

Diversity and Phylogenetic Analyses Reveal Horizontal Transmission of Endosymbionts Between Whiteflies and Their Parasitoids.

Journal of economic entomology, 112(2):894-905.

Endosymbionts are widely distributed among insects via intraspecific vertical transmission and interspecific horizontal transmission. Parasitoids have attracted considerable interest due to their possible role in the horizontal transmission of endosymbionts. Horizontal transmission of endosymbionts between whiteflies via parasitoids has been revealed in the laboratory. However, whether this occurs under field conditions remains unknown. Here, the diversity and phylogenetic relationships of endosymbionts in 1,350 whiteflies and 36 parasitoids that emerged from whitefly nymphs collected from three locations in Jiangsu Province of China were investigated. Only Rickettsia and Wolbachia were identified in both whiteflies and parasitoids, with an overall infection frequency of 22.67% in whiteflies and 16.67% in parasitoids for Wolbachia and of 12.15% in whiteflies and 25% in parasitoids for Rickettsia. Despite the distant relationship between whiteflies and their parasitoids, phylogenetic analyses revealed that the Rickettsia and Wolbachia individuals collected from the two types of organisms were grouped together. Furthermore, shared haplotypes were also identified, which was consistent with the horizontal transmission of endosymbionts between parasitoids and whiteflies. In addition, a parasitoid resistance-related symbiont, Hamiltonella, was detected in whiteflies at a 100% infection frequency, probably accounting for the relatively low parasitism of the whiteflies in the field. The factors affecting the infection frequency of the four secondary endosymbionts in whiteflies were also examined.

RevDate: 2018-12-17

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):.

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: 2018-12-17

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):.

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: 2018-12-17

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):.

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: 2018-12-17

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.

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: 2019-03-29

Lim SJ, Davis BG, Gill DE, et al (2019)

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

The ISME journal, 13(4):902-920.

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: 2019-03-05
CmpDate: 2019-03-05

McLean BJ, Dainty KR, Flores HA, et al (2019)

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

Virology, 527:141-145.

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: 2019-03-21

Sakamoto H, Suzuki R, Nishizawa N, et al (2019)

Effects of Wolbachia/Cardinium Infection on the Mitochondrial Phylogeny of Oligonychus castaneae (Acari: Tetranychidae).

Journal of economic entomology, 112(2):883-893.

A wide range of invertebrates harbor intracellular endosymbiotic bacteria. Within these endosymbionts, Wolbachia and Cardinium, have been attracting particular attention because these bacteria frequently affect the genetic structure and genetic diversity of their hosts. They cause various reproductive alterations such as cytoplasmic incompatibility, parthenogenesis induction, male-killing, and feminization. Through these alterations, they also affect the maternally inherited organelles of their hosts. Mitochondrial DNA (mtDNA) can be used for molecular phylogenetic analysis of invertebrates. However, in Wolbachia- or Cardinium-infected invertebrates, phylogenetic trees based on mtDNA are often inconsistent with those based on nuclear DNA. In the present study, we determined the Wolbachia/Cardinium infection status of 45 populations of the mite, Oligonychus castaneae Ehara & Gotoh (Acari: Tetranychidae), collected throughout Japan. Then, we compared phylogenetic trees of O. castaneae based on both the cytochrome c oxidase subunit I (COI) gene of mtDNA and the 28S rRNA gene of nuclear DNA to clarify the effects of Wolbachia and/or Cardinium infection. We found 106 Wolbachia-infected individuals and 250 Cardinium-infected individuals in a total of 450 individuals, indicating an infection rate of 79%. No double-infected individuals were observed. In the 28S tree, almost all populations formed a single group. In the COI tree, O. castaneae formed four separate groups that more closely followed Wolbachia/Cardinium infection than geographic distribution. These results strongly suggest that the endosymbionts affected mitochondrial variation of O. castaneae.

RevDate: 2019-01-29

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.

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: 2019-03-26

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.

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: 2019-03-26

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.

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: 2019-03-26

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.

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: 2019-03-26

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.

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: 2019-03-10

Bi J, Zheng Y, Wang RF, et al (2019)

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

Insect biochemistry and molecular biology, 106:47-54.

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: 2018-12-06

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

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

Nature, 564(7734):125-129.

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: 2018-12-07

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: 2019-04-16
CmpDate: 2019-04-16

Schneider DI, Ehrman L, Engl T, et al (2019)

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

Behavior genetics, 49(1):83-98.

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: 2019-03-20
CmpDate: 2019-02-19

Herran B, Cerveau N, Houdelet C, et al (2019)

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

General and comparative endocrinology, 272:9-19.

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: 2019-04-01
CmpDate: 2019-04-01

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.

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: 2019-02-12

Mohanty I, Rath A, Swain SP, et al (2019)

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

Current microbiology, 76(2):133-143.

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: 2019-03-15
CmpDate: 2019-03-15

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

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

mBio, 9(6):.

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: 2019-03-18
CmpDate: 2019-03-18

Flores-Félix JD, Sánchez-Juanes F, García-Fraile P, et al (2019)

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, 42(2):240-247.

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: 2019-02-05

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: 2019-02-21
CmpDate: 2019-02-21

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, 10(12):3218-3229 pii:5162483.

Rickettsia buchneri (formerly Rickettsia endosymbiont of Ixodes scapularis, or REIS) is an obligate intracellular endoparasite 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 Rickettsiales amplified genomic elements (RAGEs); 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.

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: 2019-01-23
CmpDate: 2019-01-23

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: 2019-04-12

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: 2019-03-11
CmpDate: 2019-03-11

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.

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.

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.

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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.

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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.

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