Viewport Size Code:
Login | Create New Account


About | Classical Genetics | Timelines | What's New | What's Hot

About | Classical Genetics | Timelines | What's New | What's Hot


Bibliography Options Menu

Hide Abstracts   |   Hide Additional Links
Long bibliographies are displayed in blocks of 100 citations at a time. At the end of each block there is an option to load the next block.

Bibliography on: Symbiosis

The Electronic Scholarly Publishing Project: Providing world-wide, free access to classic scientific papers and other scholarly materials, since 1993.


ESP: PubMed Auto Bibliography 25 Sep 2018 at 01:39 Created: 


Symbiosis refers to an interaction between two or more different organisms living in close physical association, typically to the advantage of both. Symbiotic relationships were once thought to be exceptional situations. Recent studies, however, have shown that every multicellular eukaryote exists in a tight symbiotic relationship with billions of microbes. The associated microbial ecosystems are referred to as microbiome and the combination of a multicellular organism and its microbiota has been described as a holobiont. It seems "we are all lichens now."

Created with PubMed® Query: symbiosis NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

RevDate: 2018-09-24

Duc NH, Csintalan Z, K Posta (2018)

Arbuscular mycorrhizal fungi mitigate negative effects of combined drought and heat stress on tomato plants.

Plant physiology and biochemistry : PPB, 132:297-307 pii:S0981-9428(18)30410-8 [Epub ahead of print].

Arbuscular mycorrhizal (AM) symbiosis can alleviate drought and temperature stresses in plants, but it is unknown whether the benefits can be maintained when the plants are exposed to combined drought and heat stress. In this study, the impacts of AM fungi, Septoglomus deserticola and Septoglomus constrictum on tomato plant tolerance to combined drought and heat stress were investigated. No substantial differences in physiological parameters were found in all plants under non-stress conditions, except a higher expression of SlLOXD and SlPIP2.7 in plants + S. constrictum. Under drought, heat and drought + heat stress, both fungal symbionts could moderate oxidative stress by decreasing the lipid peroxidation, hydrogen peroxide level and improving leaf and root antioxidant enzyme activities, however better performance in plants + S. constrictum. Under drought and the combined stress, inoculation with S. constrictum enhanced stomatal conductance, leaf water potential and relative water content, elevated Fv/Fm and biomass production of the hosts as compared to non-inoculated plants whilst these improvements in plants + S. deserticola were not obvious. Under the combined stress inoculation of S. constrictum did not change the expression of SlNCED and SlPIP2.7 in roots as under heat stress. Expression of SlLOXD in root were upregulated in plants + S. contrictum under drought + heat stress as in mycorrhizal roots under drought stress. Altogether, our results indicated that AM inoculation, particularly with S. constrictum had a positive influence on the tomato plant tolerance to drought + heat stress. Further studies are essential to add some light on molecular mechanisms of mycorrhizal plant tolerance to this combined stress.

RevDate: 2018-09-24
CmpDate: 2018-09-24

Wilmore JR, Gaudette BT, Gomez Atria D, et al (2018)

Commensal Microbes Induce Serum IgA Responses that Protect against Polymicrobial Sepsis.

Cell host & microbe, 23(3):302-311.e3.

Serum immunoglobulin A (IgA) antibodies are readily detected in mice and people, but the mechanisms underlying the induction of serum IgA and its role in host protection remain uncertain. We report that select commensal bacteria induce several facets of systemic IgA-mediated immunity. Exposing conventional mice to a unique but natural microflora that included several members of the Proteobacteria phylum led to T cell-dependent increases in serum IgA levels and the induction of large numbers of IgA-secreting plasma cells in the bone marrow. The resulting serum IgA bound to a restricted collection of bacterial taxa, and antigen-specific serum IgA antibodies were readily induced after intestinal colonization with the commensal bacterium Helicobacter muridarum. Finally, movement to a Proteobacteria-rich microbiota led to serum IgA-mediated resistance to polymicrobial sepsis. We conclude that commensal microbes overtly influence the serum IgA repertoire, resulting in constitutive protection against bacterial sepsis.

RevDate: 2018-09-24
CmpDate: 2018-09-24

Agafonova NV, Doronina NV, Kaparullina EN, et al (2017)

A novel Delftia plant symbiont capable of autotrophic methylotrophy.

Mikrobiologiia, 86(1):88-98.

A facultative methylotrophic bacterium, strain Lp-1, which was isolated from root nodules of lupine (Lupinus polyphyllus L.) on the medium with methanol as a carbon and energy source, exhibited high similarity of the 16S rRNA gene sequences to Delftia strains (94‒99.9%). The cells of Delftia sp. Lp-1 were motile gram-negative rods dividing by binary fission. Predominant fatty acids were C16:0 (34.2%), C16:1ω9 (14.5%), and C18:1ω7c (17.3%). Phosphatidylethanolamine, phosphatidylcholine, and phosphatidylglycerol were the dominant phospholipids. Q8 was the major ubiquinone. Optimal growth occurred at 24‒26°C and pH 7.1‒7.3; growth was inhibited by 1% NaCl. The organism oxidized methanol with the classical methanol dehydrogenase and used the ribulose bisphosphate pathway of C1 metabolism. Analysis of translated amino acid sequence of the large subunit of the MxaF methanol dehydrogenase revealed 85.5‒94% similarity to the sequences of such autotrophic methylotrophs of the class Alphaproteobacteria as Angulomicrobium, Starkeya, and Ancylobacter, indicating the possible acquisition of the mxaF gene via horizontal gene transfer. Delftia sp. Lp-1 (VKM B-3039, DSM 24446), the first methylotrophic member of the genus Delftia, was shown to be a plant symbiont, stimulating plant growth and morphogenesis, increasing the level of photosynthetic pigments and specific leaf weight. It possesses the nifH gene of nitrogen fixation, is capable of phosphate solubilization, synthesis of auxins and siderophores, and is antagonistic to plant pathogenic fungi and bacilli.

RevDate: 2018-09-21

Hess J, Skrede I, De Mares MC, et al (2018)

Rapid divergence of genome architectures following the origin of an ectomycorrhizal symbiosis in the genus Amanita.

Molecular biology and evolution pii:5100885 [Epub ahead of print].

Fungi are evolutionary shape shifters and adapt quickly to new environments. Ectomycorrhizal (EM) symbioses are mutualistic associations between fungi and plants and have evolved repeatedly and independently across the fungal tree of life, suggesting lineages frequently reconfigure genome content to take advantage of open ecological niches. To date analyses of genomic mechanisms facilitating EM symbioses have involved comparisons of distantly related species, but here, we use the genomes of three EM and two asymbiotic (AS) fungi from the genus Amanita as well as an AS outgroup to study genome evolution following a single origin of symbiosis. Our aim was to identify the defining features of EM genomes, but our analyses suggest no clear differentiation of genome size, gene repertoire size or transposable element content between EM and AS species. Phylogenetic inference of gene gains and losses suggests the transition to symbiosis was dominated by the loss of plant cell wall decomposition genes, a confirmation of previous findings. However, the same dynamic defines the AS species A. inopinata, suggesting loss is not strictly associated with origin of symbiosis. Gene expansions in the common ancestor of EM Amanita were modest, but lineage specific and large gene family expansions are found in two of the three EM extant species. Even closely related EM genomes appear to share few common features. The genetic toolkit required for symbiosis appears already encoded in the genomes of saprotrophic species, and this dynamic may explain the pervasive, recurrent evolution of ectomycorrhizal associations.

RevDate: 2018-09-21

Frare R, Ayub N, Alleva K, et al (2018)

The Ammonium Channel NOD26 is the Evolutionary Innovation that Drives the Emergence, Consolidation, and Dissemination of Nitrogen-Fixing Symbiosis in Angiosperms.

Journal of molecular evolution pii:10.1007/s00239-018-9867-3 [Epub ahead of print].

Increasing evidence indicates that N-fixing symbiosis has evolved several times in the N-fixing clade of angiosperms and that this evolution is driven by a single evolutionary innovation. However, the genetics of this ancestral predisposition to N-fixing symbiosis remains unclear. A natural candidate for such molecular innovation is the ammonium channel NOD26, the main protein component of the symbiosome membrane, which facilitates the plant uptake of the nitrogen fixed by symbiotic bacteria. Here, in concordance with the emergence of N-fixing symbiosis in angiosperms but not in ancestral plants, phylogenetic analysis showed that NOD26 belongs to an angiosperm-exclusive subgroup of aquaporins. Integrated genomic, phylogenetic, and gene expression analyses supported NOD26 occurrence in the N-fixing clade, the increase in the NOD26 copy number by block and tandem duplications in legumes, and the low-copy number or even the loss of NOD26 in non-legume species of the N-fixing clade, which correlated with the possibility to lose N-fixing symbiosis in legume and non-legume lineages. Metabolic reconstructions showed that retention of NOD26 in N-fixing precursor could represent an adaptive mechanism to bypass energy crisis during anaerobic stress by ammonium detoxification. Finally, we discuss the potential use of NOD26 to transfer N-fixation to non-N-fixing crops as cereals.

RevDate: 2018-09-21
CmpDate: 2018-09-21

Eom T, Kim YS, Choi CH, et al (2018)

Current understanding of microbiota- and dietary-therapies for treating inflammatory bowel disease.

Journal of microbiology (Seoul, Korea), 56(3):189-198.

Inflammatory bowel disease (IBD) is a result of chronic inflammation caused, in some part, by dysbiosis of intestinal microbiota, mainly commensal bacteria. Gut dysbiosis can be caused by multiple factors, including abnormal immune responses which might be related to genetic susceptibility, infection, western dietary habits, and administration of antibiotics. Consequently, the disease itself is characterized as having multiple causes, etiologies, and severities. Recent studies have identified >200 IBD risk loci in the host. It has been postulated that gut microbiota interact with these risk loci resulting in dysbiosis, and this subsequently leads to the development of IBD. Typical gut microbiota in IBD patients are characterized with decrease in species richness and many of the commensal, and beneficial, fecal bacteria such as Firmicutes and Bacteroidetes and an increase or bloom of Proteobacteria. However, at this time, cause and effect relationships have not been rigorously established. While treatments of IBD usually includes medications such as corticosteroids, 5-aminosalicylates, antibiotics, immunomodulators, and anti-TNF agents, restoration of gut dysbiosis seems to be a safer and more sustainable approach. Bacteriotherapies (now called microbiota therapies) and dietary interventions are effective way to modulate gut microbiota. In this review, we summarize factors involved in IBD and studies attempted to treat IBD with probiotics. We also discuss the potential use of microbiota therapies as one promising approach in treating IBD. As therapies based on the modulation of gut microbiota becomes more common, future studies should include individual gut microbiota differences to develop personalized therapy for IBD.

RevDate: 2018-09-21
CmpDate: 2018-09-21

Cho JA, DJF Chinnapen (2018)

Targeting friend and foe: Emerging therapeutics in the age of gut microbiome and disease.

Journal of microbiology (Seoul, Korea), 56(3):183-188.

Mucosal surfaces that line our gastrointestinal tract are continuously exposed to trillions of bacteria that form a symbiotic relationship and impact host health and disease. It is only beginning to be understood that the cross-talk between the host and microbiome involve dynamic changes in commensal bacterial population, secretion, and absorption of metabolites between the host and microbiome. As emerging evidence implicates dysbiosis of gut microbiota in the pathology and progression of various diseases such as inflammatory bowel disease, obesity, and allergy, conventional treatments that either overlook the microbiome in the mechanism of action, or eliminate vast populations of microbes via wide-spectrum antibiotics need to be reconsidered. It is also becoming clear the microbiome can influence the body's response to therapeutic treatments for cancers. As such, targeting the microbiome as treatment has garnered much recent attention and excitement from numerous research labs and biotechnology companies. Treatments range from fecal microbial transplantation to precision-guided molecular approaches. Here, we survey recent progress in the development of innovative therapeutics that target the microbiome to treat disease, and highlight key findings in the interplay between host microbes and therapy.

RevDate: 2018-09-21
CmpDate: 2018-09-21

Roberts RG (2017)

Mitochondria-A billion years of cohabitation.

PLoS biology, 15(3):e2002338 pii:pbio.2002338.

RevDate: 2018-09-20

Bilal S, Shahzad R, Khan AL, et al (2018)

Endophytic Microbial Consortia of Phytohormones-Producing Fungus Paecilomyces formosus LHL10 and Bacteria Sphingomonas sp. LK11 to Glycine max L. Regulates Physio-hormonal Changes to Attenuate Aluminum and Zinc Stresses.

Frontiers in plant science, 9:1273.

The compatible microbial consortia containing fungal and bacterial symbionts acting synergistically are applied to improve plant growth and eco-physiological responses in extreme crop growth conditions. However, the interactive effects of phytohormones-producing endophytic fungal and bacterial symbionts plant growth and stress tolerance under heavy metal stress have been least known. In the current study, the phytohormones-producing endophytic Paecilomyces formosus LHL10 and Sphingomonas sp. LK11 revealed potent growth and tolerance during their initial screening against combined Al and Zn (2.5 mM each) stress. This was followed with their co-inoculation in the Al- and Zn-stressed Glycine max L. plants, showing significantly higher plant growth attributes (shoot/root length, fresh/dry weight, and chlorophyll content) than the plants solely inoculated with LHL10 or LK11 and the non-inoculated (control) plants under metal stresses. Interestingly, under metal stress, the consortia exhibited lower metal uptake and inhibited metal transport in roots. Metal-induced oxidative stresses were modulated in co-inoculated plants through reduced hydrogen peroxide, lipid peroxidation, and antioxidant enzymes (catalase and superoxide dismutase) in comparison to the non-inoculated plants. In addition, endophytic co-inoculation enhanced plant macronutrient uptake (P, K, S, and N) and modulated soil enzymatic activities under stress conditions. It significantly downregulated the expression of heavy metal ATPase genes GmHMA13, GmHMA18, GmHMA19, and GmPHA1 and upregulated the expression of an ariadne-like ubiquitin ligase gene GmARI1 under heavy metals stress. Furthermore, the endogenous phytohormonal contents of co-inoculated plants revealed significantly enhanced gibberellins and reduced abscisic acid and jasmonic acid contents, suggesting that this endophytic interaction mitigated the adverse effect of metal stresses in host plants. In conclusion, the co-inoculation of the endophytic fungus LHL10 and bacteria LK11 actively contributed to the tripartite mutualistic symbiosis in G. max under heavy metal stresses; this could be used an excellent strategy for sustainable agriculture in the heavy metal-contaminated fields.

RevDate: 2018-09-20

Chen M, Arato M, Borghi L, et al (2018)

Beneficial Services of Arbuscular Mycorrhizal Fungi - From Ecology to Application.

Frontiers in plant science, 9:1270.

Arbuscular mycorrhiza (AM) is the most common symbiotic association of plants with microbes. AM fungi occur in the majority of natural habitats and they provide a range of important ecological services, in particular by improving plant nutrition, stress resistance and tolerance, soil structure and fertility. AM fungi also interact with most crop plants including cereals, vegetables, and fruit trees, therefore, they receive increasing attention for their potential use in sustainable agriculture. Basic research of the past decade has revealed the existence of a dedicated recognition and signaling pathway that is required for AM. Furthermore, recent evidence provided new insight into the exchange of nutritional benefits between the symbiotic partners. The great potential for application of AM has given rise to a thriving industry for AM-related products for agriculture, horticulture, and landscaping. Here, we discuss new developments in these fields, and we highlight future potential and limits toward the use of AM fungi for plant production.

RevDate: 2018-09-20

Voß S, Betz R, Heidt S, et al (2018)

RiCRN1, a Crinkler Effector From the Arbuscular Mycorrhizal Fungus Rhizophagus irregularis, Functions in Arbuscule Development.

Frontiers in microbiology, 9:2068.

Arbuscular mycorrhizal (AM) symbiosis is one of the most prominent and beneficial plant-microbe interactions that facilitates mineral nutrition and confers tolerance to biotic and abiotic stresses. AM fungi colonize the root cortex and develop specialized structures called arbuscules where the nutrient exchange takes place. Arbuscule development is a highly controlled and coordinated process requiring the involvement of many plant proteins recruited at that interface. In contrast, much less is known about the fungal proteins involved in this process. Here, we have identified an AM fungal effector that participates in this developmental step of the symbiosis. RiCRN1 is a crinkler (CRN) effector that belongs to a subfamily of secreted CRN proteins from R. irregularis. CRNs have been so far only functionally characterized in pathogenic microbes and shown to participate in processes controlling plant cell death and immunity. RiCRN1 accumulates during symbiosis establishment parallel to MtPT4, the gene coding for an arbuscule-specific phosphate transporter. Expression in Nicotiana benthamiana leaves and in Medicago truncatula roots suggest that RiCRN1 is not involved in cell death processes. RiCRN1 dimerizes and localizes to nuclear bodies, suggesting that, similar to other CRNs, it functions in the plant nucleus. Downregulation of RiCRN1 using host-induced gene silencing led to an impairment of the symbiosis in M. truncatula and to a reduction of MtPT4, while ectopic expression of RiCRN1, surprisingly, led to a drastic reduction in arbuscule size that correlated with a decrease not only in MtPT4 but also in MtBCP1, a marker for initial stages of arbuscule development. Altogether, our results suggest that a tightly regulated expression in time and space of RiCRN1 is critical for symbiosis progression and for the proper initiation of arbuscule development.

RevDate: 2018-09-20

Clerissi C, Brunet S, Vidal-Dupiol J, et al (2018)

Protists Within Corals: The Hidden Diversity.

Frontiers in microbiology, 9:2043.

Previous observations suggested that microbial communities contribute to coral health and the ecological resilience of coral reefs. However, most studies of coral microbiology focused on prokaryotes and the endosymbiotic algae Symbiodinium. In contrast, knowledge concerning diversity of other protists is still lacking, possibly due to methodological constraints. As most eukaryotic DNA in coral samples was derived from hosts, protist diversity was missed in metagenome analyses. To tackle this issue, we designed blocking primers for Scleractinia sequences amplified with two primer sets that targeted variable loops of the 18S rRNA gene (18SV1V2 and 18SV4). These blocking primers were used on environmental colonies of Pocillopora damicornis sensu lato from two regions with contrasting thermal regimes (Djibouti and New Caledonia). In addition to Symbiodinium clades A/C/D, Licnophora and unidentified coccidia genera were found in many samples. In particular, coccidian sequences formed a robust monophyletic clade with other protists identified in Agaricia, Favia, Montastraea, Mycetophyllia, Porites, and Siderastrea coral colonies. Moreover, Licnophora and coccidians had different distributions between the two geographic regions. A similar pattern was observed between Symbiodinium clades C and A/D. Although we were unable to identify factors responsible for this pattern, nor were we able to confirm that these taxa were closely associated with corals, we believe that these primer sets and the associated blocking primers offer new possibilities to describe the hidden diversity of protists within different coral species.

RevDate: 2018-09-20

Gtari M, Nouioui I, Sarkar I, et al (2018)

An update on the taxonomy of the genus Frankia Brunchorst, 1886, 174AL.

Antonie van Leeuwenhoek pii:10.1007/s10482-018-1165-y [Epub ahead of print].

Since the recognition of the name Frankia in the Approved Lists of bacterial names (1980), few amendments have been given to the genus description. Successive editions of Bergey's Manual of Systematics of Archaea and Bacteria have broadly conflicting suprageneric treatments of the genus without any advances for subgeneric classification. This review focuses on recent results from taxongenomics and phenoarray approaches to the positioning and the structuring of the genus Frankia. Based on phylogenomic analyses, Frankia should be considered the single member of the family Frankiaceae within the monophyletic order, Frankiales. A polyphasic strategy incorporating genome to genome data and omniLog® phenoarrays, together with classical approaches, has allowed the designation and an amended description of a type strain of the type species Frankia alni, and the recognition of at least 10 novel species covering symbiotic and non symbiotic taxa within the genus. Genome to phenome data will be shortly incorporated in the scheme for proposing novel species including those recalcitrant to isolation in axenic culture.

RevDate: 2018-09-20
CmpDate: 2018-09-20

Ramalho MO, Vieira AS, Pereira MC, et al (2018)

Transovarian Transmission of Blochmannia and Wolbachia Endosymbionts in the Neotropical Weaver Ant Camponotus textor (Hymenoptera, Formicidae).

Current microbiology, 75(7):866-873.

Camponotus is a hyper-diverse ant genus that is associated with the obligate endosymbiont Blochmannia, and often also with Wolbachia, but morphological studies on the location of these bacteria in the queen's ovaries during oogenesis remain limited. In the present study, we used the Neotropical weaver ant Camponotus textor to characterize the ovary using histology (HE) techniques, and to document the location of Blochmannia and Wolbachia during oogenesis through fluorescence in situ hybridization (FISH). This is the first morphological report of these two bacteria in the same host with polytrophic meroistic ovaries and reveals that Blochmannia is found inside late-stage oocytes and Wolbachia is associated with the nuclei of the nurse cells. Our results provide insights into the developmental sequence of when these bacteria reach the egg, with Blochmannia establishing itself in the egg first, and Wolbachia only reaching the egg shortly before completing egg development. Studies such as this provide understanding about the mechanisms and timing of the establishment of these endosymbionts in the host.

RevDate: 2018-09-19

Little MS, Ervin SM, Walton WG, et al (2018)

Active Site Flexibility Revealed in Crystal Structures of Parabacteroides merdae β-Glucuronidase from the Human Gut Microbiome.

Protein science : a publication of the Protein Society [Epub ahead of print].

β-Glucuronidase (GUS) enzymes in the gastrointestinal tract are involved in maintaining mammalian-microbial symbiosis and can play key roles in drug efficacy and toxicity. Parabacteroides merdae GUS was identified as an abundant mini-Loop 2 (mL2) type GUS enzyme in the Human Microbiome Project gut metagenomic database. Here, we report the crystal structure of P. merdae GUS and highlight the differences between this enzyme and extant structures of gut microbial GUS proteins. We find that P. merdae GUS exhibits a distinct tetrameric quaternary structure and that the mL2 motif traces a unique path within the active site, which also includes two arginines distinctive to this GUS. We observe two states of the P. merdae GUS active site; a loop repositions itself by more than 50 Å to place a functionally-relevant residue into the enzyme's catalytic site. Finally, we find that P. merdae GUS is able to bind to homo- and heteropolymers of the polysaccharide alginic acid. Together, these data broaden our understanding of the structural and functional diversity in the GUS family of enzymes present in the human gut microbiome and point to specialization as an important feature of microbial GUS orthologs. This article is protected by copyright. All rights reserved.

RevDate: 2018-09-19

Bharudin I, Abdul Rahim SN, Abu Bakar MF, et al (2018)

De novo transcriptome resources of the lichens, Dirinaria sp. UKM-J1 and UKM-K1 collected from Jerantut and Klang, Malaysia.

Data in brief, 19:2416-2419 pii:S2352-3409(18)30793-5.

Lichen is a symbiotic organism that exists as a single composite body consisting of a mycobiont (fungus) and a photobiont (algae or a cyanobacterium). Many lichen species are considered as extremophiles due to their tolerance to radiation, desiccation, temperature and pollution. However, not all lichen species are tolerant to harsh environmental conditions as several species are sensitive for example to nitrogen, sulphur, acidity, heavy metals, halogens (e.g. fluoride) and ozone. Thus, to better understand why some lichens can withstand exposure to pollutants as opposed to those that are susceptible, we focused on the lichen species of Dirinaria known for their wide distribution in the tropics, subtropics and pantropical, and moderate tolerance to air pollution. Their moderate tolerance to air pollution affords them to thrive in good air quality environments as well as polluted air environments. Lichen samples of Dirinaria sp., UKM-J1 and UKM-K1, were respectively collected from two areas with different levels of air quality based on Air Pollutant Index or API (with index pollutant criteria of PM10, carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide) in the outskirt of Jerantut (UKM-J1), a rural area in the middle of Peninsular Malaysia and the township of Klang (UKM-K1), in a busy area of the Klang Valley, Malaysia. API was monitored throughout 2012-2013 whereby the sample collection site in Klang showed markedly higher concentrations of pollutants in all the index pollutant criteria as compared to that of Jerantut. We performed transcriptome sequencing using Illumina RNA-seq technology and de novo assembly of the transcripts from the lichen samples. Raw reads from both libraries were deposited in the NCBI database with the accession number SRP138994.

RevDate: 2018-09-19

White JF, Kingsley KL, Verma SK, et al (2018)

Rhizophagy Cycle: An Oxidative Process in Plants for Nutrient Extraction from Symbiotic Microbes.

Microorganisms, 6(3): pii:microorganisms6030095.

In this paper, we describe a mechanism for the transfer of nutrients from symbiotic microbes (bacteria and fungi) to host plant roots that we term the 'rhizophagy cycle.' In the rhizophagy cycle, microbes alternate between a root intracellular endophytic phase and a free-living soil phase. Microbes acquire soil nutrients in the free-living soil phase; nutrients are extracted through exposure to host-produced reactive oxygen in the intracellular endophytic phase. We conducted experiments on several seed-vectored microbes in several host species. We found that initially the symbiotic microbes grow on the rhizoplane in the exudate zone adjacent the root meristem. Microbes enter root tip meristem cells-locating within the periplasmic spaces between cell wall and plasma membrane. In the periplasmic spaces of root cells, microbes convert to wall-less protoplast forms. As root cells mature, microbes continue to be subjected to reactive oxygen (superoxide) produced by NADPH oxidases (NOX) on the root cell plasma membranes. Reactive oxygen degrades some of the intracellular microbes, also likely inducing electrolyte leakage from microbes-effectively extracting nutrients from microbes. Surviving bacteria in root epidermal cells trigger root hair elongation and as hairs elongate bacteria exit at the hair tips, reforming cell walls and cell shapes as microbes emerge into the rhizosphere where they may obtain additional nutrients. Precisely what nutrients are transferred through rhizophagy or how important this process is for nutrient acquisition is still unknown.

RevDate: 2018-09-18

Insarova ID, EY Blagoveshchenskaya (2016)

Lichen Symbiosis: Search and Recognition of Partners.

Izvestiia Akademii nauk. Seriia biologicheskaia.

The problems associated with the initial stages of the formation of the thallus of lichens, i.e., compatibility of symbiotic partners, recognition ofsymbionts, and signals required for the formation of the differentiated thallus, are discussed.

RevDate: 2018-09-19
CmpDate: 2018-09-19

Kallus Y, Miller JH, E Libby (2017)

Paradoxes in leaky microbial trade.

Nature communications, 8(1):1361 pii:10.1038/s41467-017-01628-8.

Microbes produce metabolic resources that are important for cell growth yet leak into the environment. Other microbes can use these resources, adjust their own metabolic production accordingly, and alter the resources available for others. We analyze a model in which metabolite concentrations, production regulation, and population frequencies coevolve in the simple case of two cell types producing two metabolites. We identify three paradoxes where changes that should intuitively benefit a cell type actually harm it. For example, a cell type can become more efficient at producing a metabolite and its relative frequency can decrease-or alternatively the total population growth rate can decrease. Another paradox occurs when a cell type manipulates its counterpart's production so as to maximize its own instantaneous growth rate, only to achieve a lower final growth rate than had it not manipulated. These paradoxes highlight the complex and counterintuitive dynamics that emerge in simple microbial economies.

RevDate: 2018-09-18

Jarett JK, Nayfach S, Podar M, et al (2018)

Single-cell genomics of co-sorted Nanoarchaeota suggests novel putative host associations and diversification of proteins involved in symbiosis.

Microbiome, 6(1):161 pii:10.1186/s40168-018-0539-8.

BACKGROUND: Nanoarchaeota are obligate symbionts of other Archaea first discovered 16 years ago, yet little is known about this largely uncultivated taxon. While Nanoarchaeota diversity has been detected in a variety of habitats using 16S rRNA gene surveys, genome sequences have been available for only three Nanoarchaeota and their hosts. The host range and adaptation of Nanoarchaeota to a wide range of environmental conditions has thus largely remained elusive. Single-cell genomics is an ideal approach to address these questions as Nanoarchaeota can be isolated while still attached to putative hosts, enabling the exploration of cell-cell interactions and fine-scale genomic diversity.

RESULTS: From 22 single amplified genomes (SAGs) from three hot springs in Yellowstone National Park, we derived a genome-based phylogeny of the phylum Nanoarchaeota, linking it to global 16S rRNA gene diversity. By exploiting sequencing of co-sorted tightly attached cells, we associated Nanoarchaeota with 6 novel putative hosts, 2 of which were found in multiple SAGs, and showed that the same host species may associate with multiple species of Nanoarchaeota. Comparison of single nucleotide polymorphisms (SNPs) within a population of Nanoarchaeota SAGs indicated that Nanoarchaeota attached to a single host cell in situ are likely clonal. In addition to an overall pattern of purifying selection, we found significantly higher densities of non-synonymous SNPs in hypothetical cell surface proteins, as compared to other functional categories. Genes implicated in interactions in other obligate microbe-microbe symbioses, including those encoding a cytochrome bd-I ubiquinol oxidase and a FlaJ/TadC homologue possibly involved in type IV pili production, also had relatively high densities of non-synonymous SNPs.

CONCLUSIONS: This population genetics study of Nanoarchaeota greatly expands the known potential host range of the phylum and hints at what genes may be involved in adaptation to diverse environments or different hosts. We provide the first evidence that Nanoarchaeota cells attached to the same host cell are clonal and propose a hypothesis for how clonality may occur despite diverse symbiont populations.

RevDate: 2018-09-18

Checcucci A, diCenzo G, Ghini V, et al (2018)

Creation and characterization of a genomically hybrid strain in the nitrogen-fixing symbiotic bacterium Sinorhizobium meliloti.

ACS synthetic biology [Epub ahead of print].

Many bacteria, often associated with eukaryotic hosts and of relevance for biotechnological applications, harbour a multipartite genome composed of more than one replicon. Biotechnologically relevant phenotypes are often encoded by genes residing on the secondary replicons. A synthetic biology approach to developing enhanced strains for biotechnological purposes could therefore involve merging pieces or entire replicons from multiple strains into a single genome. Here we report the creation of a genomic hybrid strain in a model multipartite genome species, the plant-symbiotic bacterium Sinorhizobium meliloti. We term this strain as cis-hybrid, since it is produced by genomic material coming from the same species' pangenome. In particular, we moved the secondary replicon pSymA (accounting for nearly 20% of total genome content) from a donor S. meliloti strain to an acceptor strain. The cis-hybrid strain was screened for a panel of complex phenotypes (carbon/nitrogen utilization phenotypes, intra- and extra-cellular metabolomes, symbiosis, and various microbiological tests). Additionally, metabolic network reconstruction and constraint-based modelling were employed for in silico prediction of metabolic flux reorganization. Phenotypes of the cis-hybrid strain were in good agreement with those of both parental strains. Interestingly, the symbiotic phenotype showed a marked cultivar-specific improvement with the cis-hybrid strains compared to both parental strains. These results provide a proof-of-principle for the feasibility of genome-wide replicon-based remodelling of bacterial strains for improved biotechnological applications in precision agriculture.

RevDate: 2018-09-18
CmpDate: 2018-09-18

Frago E, Mala M, Weldegergis BT, et al (2017)

Symbionts protect aphids from parasitic wasps by attenuating herbivore-induced plant volatiles.

Nature communications, 8(1):1860 pii:10.1038/s41467-017-01935-0.

Plants respond to insect attack by releasing blends of volatile chemicals that attract their herbivores' specific natural enemies, while insect herbivores may carry endosymbiotic microorganisms that directly improve herbivore survival after natural enemy attack. Here we demonstrate that the two phenomena can be linked. Plants fed upon by pea aphids release volatiles that attract parasitic wasps, and the pea aphid can carry facultative endosymbiotic bacteria that prevent the development of the parasitic wasp larva and thus markedly improve aphid survival after wasp attack. We show that these endosymbionts also attenuate the systemic release of volatiles by plants after aphid attack, reducing parasitic wasp recruitment and increasing aphid fitness. Our results reveal a novel mechanism through which symbionts can benefit their hosts and emphasise the importance of considering the microbiome in understanding insect ecological interactions.

RevDate: 2018-09-18
CmpDate: 2018-09-18

Robinson A, Inouye DW, Ogilvie JE, et al (2017)

Multitrophic interactions mediate the effects of climate change on herbivore abundance.

Oecologia, 185(2):181-190.

Climate change can influence the abundance of insect herbivores through direct and indirect mechanisms. In this study, we evaluated multitrophic drivers of herbivore abundance for an aphid species (Aphis helianthi) in a subalpine food web consisting of a host plant (Ligusticum porteri), mutualist ants and predatory lygus bugs (Lygus spp.). We used a model-selection approach to determine which climate and host plant cues best predict year-to-year variation in insect phenology and abundance observed over 6 years. We complemented this observational study with experiments that determined how elevated temperature interacts with (1) host plant phenology and (2) the ant-aphid mutualism to determine aphid abundance. We found date of snowmelt to be the best predictor of yearly abundance of aphid and lygus bug abundance but the direction of this effect differed. Aphids achieved lower abundances in early snowmelt years likely due to increased abundance of lygus bug predators in these years. Elevating temperature of L. porteri flowering stalks reduced their quality as hosts for aphid populations. However, warming aphid colonies on host plants of similar quality increased population growth rates. Importantly, this effect was apparent even in the absence of ants. While we observed fewer ants tending colonies at elevated temperatures, these colonies also had reduced numbers of lygus bug predators. This suggests that mutualism with ants becomes less significant as temperature increases, which contrasts other ant-hemipteran systems. Our observational and experimental results show the importance of multitrophic species interactions for predicting the effect of climate change on the abundances of herbivores.

RevDate: 2018-09-17

Montero H, Choi J, U Paszkowski (2018)

Arbuscular mycorrhizal phenotyping: the dos and don'ts.

The New phytologist [Epub ahead of print].

Most plant lineages engage with Glomeromycotina fungi to form the ubiquitous arbuscular mycorrhizal (AM) symbiosis. Despite its wide occurrence in diverse plant-fungal species combinations, the interaction dynamics are strikingly uniform (Fig. 1). The events leading up to a successful mutualism start when plant and fungus advertise their presence in the rhizosphere by releasing diffusible chemical cues. This article is protected by copyright. All rights reserved.

RevDate: 2018-09-17
CmpDate: 2018-09-17

Kobiałka M, Michalik A, Szwedo J, et al (2018)

Diversity of symbiotic microbiota in Deltocephalinae leafhoppers (Insecta, Hemiptera, Cicadellidae).

Arthropod structure & development, 47(3):268-278.

Symbiotic microorganisms associated with thirteen species of the subfamily Deltocephalinae were examined using microscopic and molecular techniques. Athysanus argentarius, Euscelis incisus, Doratura stylata, Arthaldeus pascuellus, Errastunus ocellaris, Jassargus flori, Jassargus pseudocellaris, Psammotettix alienus, Psammotettix confinis, Turrutus socialis and Verdanus abdominalis harbor two types of ancient bacteriome-associated microorganisms: bacteria Sulcia (phylum Bacteroidetes) and bacteria Nasuia (phylum Proteobacteria, class Betaproteobacteria). In Balclutha calamagrostis and Balclutha punctata, the bacterium Nasuia has not been detected. In the bacteriomes of both species of Balclutha examined, only bacteria Sulcia occur, whereas Sodalis-like symbionts (phylum Proteobacteria, class Gammaproteobacteria) are localized in the fat body cells, in close vicinity of the bacteriomes. To our knowledge, this is the first report of the co-existence in Deltocephalinae leafhoppers of the ancient symbiont Sulcia and the more recently acquired Sodalis-like bacterium. The obtained results provide further evidence indicating that Deltocephalinae leafhoppers are characterized by a large diversity of symbiotic systems, which results from symbiont acquisition and replacement. The obtained results are additionally discussed in phylogenetic context.

RevDate: 2018-09-17
CmpDate: 2018-09-17

Lace B, T Ott (2018)

Commonalities and Differences in Controlling Multipartite Intracellular Infections of Legume Roots by Symbiotic Microbes.

Plant & cell physiology, 59(4):661-672.

Legumes have the almost unique ability to establish symbiotic associations with rhizobia and arbuscular mycorrhizal fungi. Forward and reverse genetics have identified a large number of genes that are required for either or both interactions. However, and in sharp contrast to natural soils, these interactions have been almost exclusively investigated under laboratory conditions by using separate inoculation systems, whereas both symbionts are simultaneously present in the field. Considering our recent understanding of the individual symbioses, the community is now promisingly positioned to co-inoculate plants with two or more microbes in order to understand mechanistically how legumes efficiently balance, regulate and potentially separate these symbioses and other endophytic microbes within the same root. Here, we discuss a number of key control layers that should be considered when assessing tri- or multipartite beneficial interactions and that may contribute to colonization patterns in legume roots.

RevDate: 2018-09-17
CmpDate: 2018-09-17

Feng G, Sun W, Zhang F, et al (2018)

Functional Transcripts Indicate Phylogenetically Diverse Active Ammonia-Scavenging Microbiota in Sympatric Sponges.

Marine biotechnology (New York, N.Y.), 20(2):131-143.

Symbiotic ammonia scavengers contribute to effective removal of ammonia in sponges. However, the phylogenetic diversity and in situ activity of ammonia-scavenging microbiota between different sponge species are poorly addressed. Here, transcribed ammonia monooxygenase genes (amoA), hydrazine synthase genes (hzsA), and glutamine synthetase genes (glnA) were analyzed to reveal the active ammonia-scavenging microbiota in the sympatric sponges Theonella swinhoei, Plakortis simplex, and Phakellia fusca, and seawater. Archaeal amoA and bacterial glnA transcripts rather than bacterial amoA, hzsA, and archaeal glnA transcripts were detected in the investigated sponges and seawater. The transcribed amoA genes were ascribed to two Thaumarchaeota ecotypes, while the transcribed glnA genes were interspersed among the lineages of Cyanobacteria, Tectomicrobia, Poribacteria, Alpha-, Beta-, Gamma-, and Epsilonproteobacteria. In addition, transcribed abundances of archaeal amoA and bacterial glnA genes in these sponges have been quantified, showing significant variation among the investigated sponges and seawater. The transcriptome-based qualitative and quantitative analyses clarified the different phylogenetic diversity and transcription expression of functional genes related to microbially mediated ammonia scavenging in different sympatric sponges, contributing to the understanding of in situ active ecological functions of sponge microbial symbionts in holobiont nitrogen cycling.

RevDate: 2018-09-17
CmpDate: 2018-09-17

Carella P, S Schornack (2018)

Manipulation of Bryophyte Hosts by Pathogenic and Symbiotic Microbes.

Plant & cell physiology, 59(4):651-660.

The colonization of plant tissues by pathogenic and symbiotic microbes is associated with a strong and directed effort to reprogram host cells in order to permit, promote and sustain microbial growth. In response to colonization, hosts accommodate or sequester invading microbes by activating a set of complex regulatory programs that initiate symbioses or bolster defenses. Extensive research has elucidated a suite of molecular and physiological responses occurring in plant hosts and their microbial partners; however, this information is mostly limited to model systems representing evolutionarily young plant lineages such as angiosperms. The extent to which these processes are conserved across land plants is therefore poorly understood. In this review, we outline key aspects of host reprogramming that occur during plant-microbe interactions in early diverging land plants belonging to the bryophytes (liverworts, hornworts and mosses). We discuss how further knowledge of bryophyte-microbe interactions will advance our understanding of how plants and microbes co-operated and clashed during the conquest of land.

RevDate: 2018-09-17
CmpDate: 2018-09-17

Martínez-García LB, De Deyn GB, Pugnaire FI, et al (2017)

Symbiotic soil fungi enhance ecosystem resilience to climate change.

Global change biology, 23(12):5228-5236.

Substantial amounts of nutrients are lost from soils through leaching. These losses can be environmentally damaging, causing groundwater eutrophication and also comprise an economic burden in terms of lost agricultural production. More intense precipitation events caused by climate change will likely aggravate this problem. So far it is unresolved to which extent soil biota can make ecosystems more resilient to climate change and reduce nutrient leaching losses when rainfall intensity increases. In this study, we focused on arbuscular mycorrhizal (AM) fungi, common soil fungi that form symbiotic associations with most land plants and which increase plant nutrient uptake. We hypothesized that AM fungi mitigate nutrient losses following intensive precipitation events (higher amount of precipitation and rain events frequency). To test this, we manipulated the presence of AM fungi in model grassland communities subjected to two rainfall scenarios: moderate and high rainfall intensity. The total amount of nutrients lost through leaching increased substantially with higher rainfall intensity. The presence of AM fungi reduced phosphorus losses by 50% under both rainfall scenarios and nitrogen losses by 40% under high rainfall intensity. Thus, the presence of AM fungi enhanced the nutrient interception ability of soils, and AM fungi reduced the nutrient leaching risk when rainfall intensity increases. These findings are especially relevant in areas with high rainfall intensity (e.g., such as the tropics) and for ecosystems that will experience increased rainfall due to climate change. Overall, this work demonstrates that soil biota such as AM fungi can enhance ecosystem resilience and reduce the negative impact of increased precipitation on nutrient losses.

RevDate: 2018-09-17
CmpDate: 2018-09-17

Lugsomya K, Chatsuwan T, Niyomtham W, et al (2018)

Routine Prophylactic Antimicrobial Use Is Associated with Increased Phenotypic and Genotypic Resistance in Commensal Escherichia coli Isolates Recovered from Healthy Fattening Pigs on Farms in Thailand.

Microbial drug resistance (Larchmont, N.Y.), 24(2):213-223.

This study examined antimicrobial resistance (AMR) profiles in commensal Escherichia coli derived from healthy fattening pigs in Thai farms that used prophylactic antimicrobials (in-feed tiamulin fumarate and amoxicillin) [PAs], therapeutic antimicrobials (injectable enrofloxacin or gentamicin) [TAs], or no antimicrobials [NAs]. Commensal E. coli were used as a proxy for overall AMR on the farms. There was a high level of multidrug resistance in all three categories of farm, with isolates showing resistance to β-lactams (amoxicillin, ampicillin, and piperacillin) and tetracyclines (tetracycline), and commonly possessing tetA, blaTEM, and plasmid replicons FIB and F. On the other hand, isolates with an extended-spectrum beta-lactamase phenotype (ESBLP) and with resistance to aminoglycosides, chloramphenicol, fluoroquinolones, nitrofurantoin, tiamulin, and trimethoprim/sulfamethoxazole were significantly more common among the PA farms (p < 0.05) than in the other two farm categories. In the PA farms, ESBLP E. coli commonly contained the blaCTX-M-1 group, blaCTX-M-9 group, or both gene groups, and were shown to transfer blaCTX-M genes in a conjugation experiment. E. coli containing N, FIC and A/C replicons were found only in PA farms. In summary, although E. coli isolates from all farms contained a core set of resistance to β-lactams and tetracyclines, the routine use of PA increased resistance rates to other important antimicrobials.

RevDate: 2018-09-16

Cremon C, Barbaro MR, Ventura M, et al (2018)

Pre- and probiotic overview.

Current opinion in pharmacology, 43:87-92 pii:S1471-4892(18)30083-3 [Epub ahead of print].

The dynamic relationship between gut microbiota and its human host is also known as a trophic association that might range from commensalism, where only the microbe enjoys a positive effect from the relationship, to intestinal symbiosis where both host and microbe benefit from their interaction. In the last years, we have started to understand how alterations of the gut microbiota composition leading to the disruption of host-microbial interactions are associated and/or predispose individuals to disease conditions ranging from inflammatory bowel diseases to allergy and functional gastrointestinal disorders, such as irritable bowel syndrome. While we await important insights in this field, the microbiota is already a therapeutic target. Based on the actual definitions, prebiotics are defined as substrates that are selectively utilized by host microorganisms conferring a health benefit, while probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Although their health promoting activities encompasses numerous effects, including immunostimulation, competitive exclusion of pathogens, and gut barrier enhancement, the exact mechanism of action by which these compounds exert their beneficial actions in humans is only partially known. In this review, we highlight the current insights into the clinical applications of prebiotics and probiotics in gastroenterology.

RevDate: 2018-09-15

Porter SS, Faber-Hammond J, Montoya AP, et al (2018)

Dynamic genomic architecture of mutualistic cooperation in a wild population of Mesorhizobium.

The ISME journal pii:10.1038/s41396-018-0266-y [Epub ahead of print].

Research on mutualism seeks to explain how cooperation can be maintained when uncooperative mutants co-occur with cooperative kin. Gains and losses of the gene modules required for cooperation punctuate symbiont phylogenies and drive lifestyle transitions between cooperative symbionts and uncooperative free-living lineages over evolutionary time. Yet whether uncooperative symbionts commonly evolve from within cooperative symbiont populations or from within distantly related lineages with antagonistic or free-living lifestyles (i.e., third-party mutualism exploiters or parasites), remains controversial. We use genomic data to show that genotypes that differ in the presence or absence of large islands of symbiosis genes are common within a single wild recombining population of Mesorhizobium symbionts isolated from host tissues and are an important source of standing heritable variation in cooperation in this population. In a focal population of Mesorhizobium, uncooperative variants that lack a symbiosis island segregate at 16% frequency in nodules, and genome size and symbiosis gene number are positively correlated with cooperation. This finding contrasts with the genomic architecture of variation in cooperation in other symbiont populations isolated from host tissues in which the islands of genes underlying cooperation are ubiquitous and variation in cooperation is primarily driven by allelic substitution and individual gene gain and loss events. Our study demonstrates that uncooperative mutants within mutualist populations can comprise a significant component of genetic variation in nature, providing biological rationale for models and experiments that seek to explain the maintenance of mutualism in the face of non-cooperators.

RevDate: 2018-09-15

Schwob G, Roy M, Pozzi CA, et al (2018)

In planta sporulation of Frankia as a determinant of alder-symbionts interactions.

Applied and environmental microbiology pii:AEM.01737-18 [Epub ahead of print].

Alnus genus forms symbiosis with the actinobacteria Frankia and ectomycorrhizal fungi. Two types of Frankia lineages can be distinguished based on their ability to sporulate in planta. Spore-positive (Sp+) strains are predominant on Alnus incana (Ai) and Alnus viridis (Av) in highlands, while spore-negative (Sp-) strains are mainly associated with Alnus glutinosa (Ag) in lowlands. Here, we investigated whether the Sp+ predominance in nodules is due to host selection of certain Frankia genotypes from soil communities or the result of the ecological history of the alder stand soil, and the effect of the sporulation genotype on the ECM communities. Trapping experiments were conducted using Ag, Ai and Av plantlets on 6 soils, differing in the alder species and the frequency of Sp+ nodules in the field. Higher diversity of Frankia and variation in Sp+ frequencies were observed in the trapping compared to the fields. Both indigenous and trapping species shape Frankia community structure in trapped nodules. Nodulation impediments were observed on several trapping conditions in Sp+ soils supporting a narrower host-range of Sp+ FrankiaAi and Av were able to associate equally with compatible Sp+ and Sp- in the greenhouse. Additionally, no host shift was observed for Alnus-specific ECM, and the sporulation genotype of Frankia defined the ECM communities on the host roots. The symbiotic association is likely determined by the host-range, the soil history and the type of in planta Frankia These results provide an insight into the biogeographical drivers of alder symbionts in the Holarctic region.Importance Most Frankia-actinorhizal plant symbioses are capable of high rates of nitrogen fixation comparable to those found on legumes. Yet our understanding of the ecology and distribution of Frankia is still very limited. Several studies have focused on the distribution patterns of Frankia, demonstrating a combination of host and pedoclimatic parameters in their biogeography. However, very few have considered the in planta sporulation form of the strain, although it is a unique feature among all symbiotic plant-associated microbes. Compared with Sp- Frankia strains, Sp+ would be obligate symbionts, highly dependent on the presence of a compatible host-species and with lower efficiency in nitrogen fixation. Understanding the biogeographical drivers of Sp+ Frankia strains might help to elucidate the ecological role of in planta sporulation, and the extent to which this trait mediates host-partner interactions in the alder-Frankia-ECM fungi symbiosis.

RevDate: 2018-09-15

Benndorf R, Guo H, Sommerwerk E, et al (2018)

Natural Products from Actinobacteria Associated with Fungus-Growing Termites.

Antibiotics (Basel, Switzerland), 7(3): pii:antibiotics7030083.

The chemical analysis of insect-associated Actinobacteria has attracted the interest of natural product chemists in the past years as bacterial-produced metabolites are sought to be crucial for sustaining and protecting the insect host. The objective of our study was to evaluate the phylogeny and bioprospecting of Actinobacteria associated with fungus-growing termites. We characterized 97 Actinobacteria from the gut, exoskeleton, and fungus garden (comb) of the fungus-growing termite Macrotermes natalensis and used two different bioassays to assess their general antimicrobial activity. We selected two strains for chemical analysis and investigated the culture broth of the axenic strains and fungus-actinobacterium co-cultures. From these studies, we identified the previously-reported PKS-derived barceloneic acid A and the PKS-derived rubterolones. Analysis of culture broth yielded a new dichlorinated diketopiperazine derivative and two new tetracyclic lanthipeptides, named rubrominins A and B. The discussed natural products highlight that insect-associated Actinobacteria are highly prolific natural product producers yielding important chemical scaffolds urgently needed for future drug development programs.

RevDate: 2018-09-14

Tsuji K, T Fukami (2018)

Community-wide consequences of sexual dimorphism: evidence from nectar microbes in dioecious plants.

Ecology [Epub ahead of print].

Intraspecific trait variation is receiving renewed interest as a factor affecting the structure of multi-species communities within and across trophic levels. One pervasive form of intraspecific trait variation is sexual dimorphism in animals and plants, which might exert large effects particularly on the communities of host-associated organisms, but the extent of these effects is not well understood. We investigated whether host-associated microbial communities developed differently in the floral nectar of female and male individuals of the dioecious shrubs, Eurya emarginata and E. japonica. We found that nectar-colonizing microbes such as bacteria and fungi were more than twice as prevalent and, overall, more than 10 times as abundant in male flowers as in female flowers. Microbial species composition also differed between flower sexes. To examine potential mechanisms behind these differences, we manipulated the frequency of flower visitation by animals and the order of arrival of microbial species to nectar. Animal visitation frequency affected microbial communities more greatly in male flowers, while arrival order affected them more in female flowers. These sex-specific effects appeared attributable to differences in how animals and microbes altered the chemical characteristics of nectar that limited microbial growth. Taken together, our results provide evidence that sexual dimorphism can have large effects on the structure of host-associated communities.

RevDate: 2018-09-14

Vasilchenko AS, Gritsenko VA, Kosyan DB, et al (2018)

A Low-Molecular-Weight Compound Derived from Human Leukocytes Determines a Bactericidal Activity of the Interferon Preparation.

Probiotics and antimicrobial proteins pii:10.1007/s12602-018-9463-2 [Epub ahead of print].

The aim of this study was to characterize the structure and mode of action of antimicrobials derived from a commercial preparation of alfa-interferon. By combination of semi-preparative/analytical reversed-phase high-performance liquid chromatography, we isolated and purified a novel active substance based on carbohydrate with a complex of amino acids, which determines antimicrobial property of commercial preparation of interferon. A size-exclusion chromatography was performed and LC/ESI-MS revealed molecular masses of active substance were in the range of 180-249 Da. Edman sequencing identified phenylthiohydantoin (PTH) derivatives which consisted a set of preliminary (Asp, Glu, Gly, and Ala) and minor amino acids (Leu and Thr) at equimolar ratio. Thus, the purified active substance is a compound containing the complex of amino acids connected with carbohydrate background and called leucidin. Leucidin demonstrated antimicrobial activity against the model Escherichia coli (E. coli) K12 strain at a minimal inhibitory concentration of 20 μg mL-1. The revealed antimicrobial mechanism of action is associated with violation of the bacterial cell wall leading to a SOS response and bacterial autolysis. Despite the preliminary nature of the results, obtained data allowed us to discover the previously unknown leukocyte-derived antimicrobial molecules.

RevDate: 2018-09-14
CmpDate: 2018-09-14

Julius RS, Schwan EV, CT Chimimba (2018)

Molecular characterization of cosmopolitan and potentially co-invasive helminths of commensal, murid rodents in Gauteng Province, South Africa.

Parasitology research, 117(6):1729-1736.

Concurrent studies of helminth parasites of introduced and native rodent species are few and miss the opportunity to identify potential co-invasive parasite species. This study employed molecular tools to infer the phylogeny and elucidate the origin of potentially co-invasive parasites of commensal, murid rodents by assessing introduced Rattus norvegicus, Rattus rattus, Rattus tanezumi, and native Mastomys coucha in Gauteng Province, South Africa. Genotypes of Nippostrongylus brasiliensis recovered from R. norvegicus are nearly identical to those recovered from elsewhere in the world. The pinworms, Aspiculurus tetraptera, recovered from introduced R. tanezumi and R. rattus, Syphacia muris recovered from R. tanezumi, and Syphacia obvelata recovered from indigenous M. coucha have affiliations to those recovered of laboratory rodents from the USA and China. Syphacia obvelata was previously only known as a commensal endoparasite of laboratory rodents, and the S. muris genotype recovered from R. tanezumi in this study shows an affiliation to a genotype recovered from the same host species in Indonesia which is part of the native range. The study emphasizes the need for surveillance of potential co-invasive species and contributes in documenting genetic diversity of endoparasites of well-known hosts.

RevDate: 2018-09-13

Saramago M, Robledo M, Matos RG, et al (2018)

Sinorhizobium meliloti RNase III: Catalytic Features and Impact on Symbiosis.

Frontiers in genetics, 9:350.

Members of the ribonuclease (RNase) III family of enzymes are metal-dependent double-strand specific endoribonucleases. They are ubiquitously found and eukaryotic RNase III-like enzymes include Dicer and Drosha, involved in RNA processing and RNA interference. In this work, we have addressed the primary characterization of RNase III from the symbiotic nitrogen-fixing α-proteobacterium Sinorhizobium meliloti. The S. meliloti rnc gene does encode an RNase III-like protein (SmRNase III), with recognizable catalytic and double-stranded RNA (dsRNA)-binding domains that clusters in a branch with its α-proteobacterial counterparts. Purified SmRNase III dimerizes, is active at neutral to alkaline pH and behaves as a strict metal cofactor-dependent double-strand endoribonuclease, with catalytic features distinguishable from those of the prototypical member of the family, the Escherichia coli ortholog (EcRNase III). SmRNase III prefers Mn2+ rather than Mg2+ as metal cofactor, cleaves the generic structured R1.1 substrate at a site atypical for RNase III cleavage, and requires higher cofactor concentrations and longer dsRNA substrates than EcRNase III for optimal activity. Furthermore, the ultraconserved E125 amino acid was shown to play a major role in the metal-dependent catalysis of SmRNase III. SmRNase III degrades endogenous RNA substrates of diverse biogenesis with different efficiency, and is involved in the maturation of the 23S rRNA. SmRNase III loss-of-function neither compromises viability nor alters morphology of S. meliloti cells, but influences growth, nodulation kinetics, the onset of nitrogen fixation and the overall symbiotic efficiency of this bacterium on the roots of its legume host, alfalfa, which ultimately affects plant growth. Our results support an impact of SmRNase III on nodulation and symbiotic nitrogen fixation in plants.

RevDate: 2018-09-13

Mars Brisbin M, Mesrop LY, Grossmann MM, et al (2018)

Intra-host Symbiont Diversity and Extended Symbiont Maintenance in Photosymbiotic Acantharea (Clade F).

Frontiers in microbiology, 9:1998.

Photosymbiotic protists contribute to surface primary production in low-nutrient, open-ocean ecosystems and constitute model systems for studying plastid acquisition via endosymbiosis. Little is known, however, about host-symbiont dynamics in these important relationships, and whether these symbioses are mutualistic is debated. In this study, we applied single-cell sequencing methods and advanced fluorescent microscopy to investigate host-symbiont dynamics in clade F acantharians, a major group of photosymbiotic protists in oligotrophic subtropical gyres. We amplified the 18S rRNA gene from single acantharian hosts and environmental samples to assess intra-host symbiont diversity and to determine whether intra-host symbiont community composition directly reflects the available symbiont community in the surrounding environment. Our results demonstrate that clade F acantharians simultaneously host multiple species from the haptophyte genera Phaeocystis and Chrysochromulina. The intra-host symbiont community composition was distinct from the external free-living symbiont community, suggesting that these acantharians maintain symbionts for extended periods of time. After selectively staining digestive organelles, fluorescent confocal microscopy showed that symbionts were not being systematically digested, which is consistent with extended symbiont maintenance within hosts. Extended maintenance within hosts may benefit symbionts through protection from grazing or viral lysis, and therefore could enhance dispersal, provided that symbionts retain reproductive capacity. The evidence for extended symbiont maintenance therefore allows that Phaeocystis could glean some advantage from the symbiosis and leaves the possibility of mutualism.

RevDate: 2018-09-13

Niehs SP, Scherlach K, C Hertweck (2018)

Genomics-driven discovery of a linear lipopeptide promoting host colonization by endofungal bacteria.

Organic & biomolecular chemistry [Epub ahead of print].

The rice seedling blight fungus Rhizopus microsporus weakens or kills plants by means of a potent toxin produced by endobacteria (Burkholderia rhizoxinica) that live within the fungal hyphae. The success of the highly attuned microbial interaction is partly based on the bacteria's ability to roam and re-colonize the fungal host. Yet, apart from the toxin, chemical mediators of the symbiosis have remained elusive. By genome mining and comparison we identified a cryptic NRPS gene cluster that is conserved among all sequenced Rhizopus endosymbionts. Metabolic profiling and targeted gene inactivation led to the discovery of a novel linear lipopeptide, holrhizin A, which was fully characterized. Through in vitro and in vivo assays we found that holrhizin acts (A) as a biosurfactant to reduce surface tension, (B) influences the formation of mature biofilms and thus cell motility behavior that ultimately supports the bacterial cells to (C) colonize and invade the fungal host, consequently supporting the re-establishment of the exceptional Burkholderia-Rhizopus symbiosis. We not only unveil structure and function of an linear lipopeptide from endofungal bacteria but also provide a functional link between the symbiont's orphan NRPS genes and a chemical mediator that promotes bacterial invasion into the fungal host.

RevDate: 2018-09-13

Xue L, Klinnawee L, Zhou Y, et al (2018)

AP2 transcription factor CBX1 with a specific function in symbiotic exchange of nutrients in mycorrhizal Lotus japonicus.

Proceedings of the National Academy of Sciences of the United States of America pii:1812275115 [Epub ahead of print].

The arbuscular mycorrhizal (AM) symbiosis, a widespread mutualistic association between land plants and fungi, depends on reciprocal exchange of phosphorus driven by proton-coupled phosphate uptake into host plants and carbon supplied to AM fungi by host-dependent sugar and lipid biosynthesis. The molecular mechanisms and cis-regulatory modules underlying the control of phosphate uptake and de novo fatty acid synthesis in AM symbiosis are poorly understood. Here, we show that the AP2 family transcription factor CTTC MOTIF-BINDING TRANSCRIPTION FACTOR1 (CBX1), a WRINKLED1 (WRI1) homolog, directly binds the evolutionary conserved CTTC motif that is enriched in mycorrhiza-regulated genes and activates Lotus japonicus phosphate transporter 4 (LjPT4) in vivo and in vitro. Moreover, the mycorrhiza-inducible gene encoding H+-ATPase (LjHA1), implicated in energizing nutrient uptake at the symbiotic interface across the periarbuscular membrane, is coregulated with LjPT4 by CBX1. Accordingly, CBX1-defective mutants show reduced mycorrhizal colonization. Furthermore, genome-wide-binding profiles, DNA-binding studies, and heterologous expression reveal additional binding of CBX1 to AW box, the consensus DNA-binding motif for WRI1, that is enriched in promoters of glycolysis and fatty acid biosynthesis genes. We show that CBX1 activates expression of lipid metabolic genes including glycerol-3-phosphate acyltransferase RAM2 implicated in acylglycerol biosynthesis. Our finding defines the role of CBX1 as a regulator of host genes involved in phosphate uptake and lipid synthesis through binding to the CTTC/AW molecular module, and supports a model underlying bidirectional exchange of phosphorus and carbon, a fundamental trait in the mutualistic AM symbiosis.

RevDate: 2018-09-12

Becker A (2017)

Classic Spotlight: Bacteroids-Views of an Enigmatic Bacterial State in Root Nodule Symbiosis through the Centuries.

Journal of bacteriology, 199(3): pii:199/3/e00741-16.

RevDate: 2018-09-13
CmpDate: 2018-09-13

Safronova VI, Belimov AA, Sazanova AL, et al (2018)

Taxonomically Different Co-Microsymbionts of a Relict Legume, Oxytropis popoviana, Have Complementary Sets of Symbiotic Genes and Together Increase the Efficiency of Plant Nodulation.

Molecular plant-microbe interactions : MPMI, 31(8):833-841.

Ten rhizobial strains were isolated from root nodules of a relict legume Oxytropis popoviana Peschkova. For identification of the isolates, sequencing of rrs, the internal transcribed spacer region, and housekeeping genes recA, glnII, and rpoB was used. Nine fast-growing isolates were Mesorhizobium-related; eight strains were identified as M. japonicum and one isolate belonged to M. kowhaii. The only slow-growing isolate was identified as a Bradyrhizobium sp. Two strains, M. japonicum Opo-242 and Bradyrhizobium sp. strain Opo-243, were isolated from the same nodule. Symbiotic genes of these isolates were searched throughout the whole-genome sequences. The common nodABC genes and other symbiotic genes required for plant nodulation and nitrogen fixation were present in the isolate Opo-242. Strain Opo-243 did not contain the principal nod, nif, and fix genes; however, five genes (nodP, nodQ, nifL, nolK, and noeL) affecting the specificity of plant-rhizobia interactions but absent in isolate Opo-242 were detected. Strain Opo-243 could not induce nodules but significantly accelerated the root nodule formation after coinoculation with isolate Opo-242. Thus, we demonstrated that taxonomically different strains of the archaic symbiotic system can be co-microsymbionts infecting the same nodule and promoting the nodulation process due to complementary sets of symbiotic genes.

RevDate: 2018-09-13
CmpDate: 2018-09-13

Rowe SL, Norman JS, ML Friesen (2018)

Coercion in the Evolution of Plant-Microbe Communication: A Perspective.

Molecular plant-microbe interactions : MPMI, 31(8):789-794.

Plants and microbes are dependent on chemical signals as a means of interkingdom communication. There are two predicted paths for the evolution of these signals. Ritualization is the oft-assumed pathway for the evolution of plant-microbe communication systems. In this process, chemical signals, which benefit both receiver and sender, evolve from chemical cues, which benefit only the receiver. However, plant-microbe signaling may evolve from coercive interactions as well, a process known as sensory manipulation. Here, we aim to highlight the prevalence of coercive interactions and discuss sensory manipulation in the context of plant-microbe interactions. We present two examples of stabilized coercion: microbial coercion of plants via the release of phytohormones and plant coercion of microbes via manipulation of quorum-sensing compounds. Furthermore, we provide an evolutionary framework for the emergence of signaling from coercive plant-microbe interactions through the process of sensory manipulation. We hope that researchers will recognize the relevance of coercive interactions in plant-microbe systems and consider sensory manipulation as a plausible evolutionary trajectory for the emergence of plant-microbe signaling.

RevDate: 2018-09-12
CmpDate: 2018-09-12

Ramamoorthy S, Gnanakan A, S Lakshmana S, et al (2018)

Structural characterization and anticancer activity of extracellular polysaccharides from ascidian symbiotic bacterium Bacillus thuringiensis.

Carbohydrate polymers, 190:113-120.

In the present study, extracellular polysaccharides (EPS) producing bacterium Bacillus thuringiensis RSK CAS4 was isolated from ascidian Didemnum granulatum and its production was optimized by response surface methodology. Fructose and galactose were found as the major monosaccharides in the EPS from the strain RSK CAS4. Functional groups and structural characteristics of the EPS were characterized with FT-IR and 1HNMR. The purified EPS showed potent antioxidant properties in investigation against DPPH, hydroxyl, superoxide free radicals. In vitro anticancer activity of purified EPS was evaluated on HEp-2 cells, A549 and Vero cell lines. Growth of cancer cells was inhibited by the EPS in a dose-dependent manner and maximum anticancer activity was found to be 76% against liver cancer at 1000 μg/ml. The antioxidant and anticancer potentials of theEPS from marine bacterium Bacillusthuringiensis RSK CAS4 suggests it as a potential natural source and its scopeas an alternative to synthetics for pharmaceutical application.

RevDate: 2018-09-12
CmpDate: 2018-09-12

Ong JWL, Li H, Sivasithamparam K, et al (2018)

Novel and divergent viruses associated with Australian orchid-fungus symbioses.

Virus research, 244:276-283.

Terrestrial orchids represent a symbiotic union between plants and mycorrhizal fungi. This study describes the occurrence and nature of viruses associated with one population of wild Pterostylis sanguinea orchids, including their fungal symbionts, over two consecutive years. A generic sequencing approach, which combined dsRNA-enrichment from plant and mycelial tissues, random amplification and high throughput shotgun sequencing was used to identify novel viruses. The majority of the virus-like sequences represent partial genomes, and their identification is based solely on de novo assembly of sequencing data. In orchid leaf tissues we found three isolates of a novel totivirus and an unclassified virus; both resemble fungus-infecting viruses. Two isolates of Ceratobasidium sp that were isolated from orchid underground stems contained at least 20 viruses, 16 of which were previously described as alphapartitiviruses and betapartitiviruses. A novel hypovirus and a mitovirus were genetically distant from existing members of the genera and did not readily fit into recognised subgroups.

RevDate: 2018-09-12
CmpDate: 2018-09-12

Krutylo DV, NO Leonova (2016)

Symbiotic Potential of Bradyrhizobium japonicum Strains with Different Growth Rates.

Mikrobiolohichnyi zhurnal (Kiev, Ukraine : 1993), 78(5):42-52.

Aim: To study genetic properties of soybean nodule bacteria with different growth rates, to research the ability of rhizobia to produce phytohormonal substances and estimate their symbiotic potential in the conditions of combined inoculation and mono-inoculation of soybean plants.

Methods: Sequencing of the 16S-23S rDNA intergenic spacer of soybean rhizobia was performed on ABI 3130xl Genetic Analyzer. Determination of the qualitative and quantitative composition of phytohormones in culture liquid of Bradyrhizobium japonicum strains was performed by SDTLC-chromatography of high resolution. Symbiotic potential of the strains was estimated in the field experiment in Polissia area of Ukraine.

Results: It has been established that strains of soybean nodule bacteria with different growth rates by the structure of ITS region belong to different genetic groups: USDA 6, USDA 110 and USDA 123. The studied rhizobia differ in the levels of extracellular phytohormones synthesis: the slow-growing B. japonicum strain 46 produces more amounts of auxins, but the intensive-growing B. japonicum strain KB11 significantly exceeds in the amounts of cytokinins. It has been shown that an important factor of increasing soybean productivity is the formation of balanced symbiotic systems of the host plant with several complementary strains but serologically and genetically different strains of rhizobia of the same species.

Conclusions: Combined inoculation of soybean seeds with two active strains B. japonicum 46 and B. japonicum KB11 allows more fully realizing the potential of symbiotic partners and receiving the higher yield.

RevDate: 2018-09-11

diCenzo GC, Zamani M, Checcucci A, et al (2018)

Multi-disciplinary approaches for studying rhizobium - legume symbioses.

Canadian journal of microbiology [Epub ahead of print].

The rhizobium-legume symbiosis is a major source of fixed nitrogen (ammonia) in the biosphere. The potential for this process to increase agricultural yield while reducing the reliance on nitrogen-based fertilizers has generated interest in understanding and manipulating this process. For decades, rhizobium research has benefited from the use of leading techniques from a very broad set of fields, including population genetics, molecular genetics, genomics, and systems biology. In this review, we summarize many of the research strategies that have been employed in the study of rhizobia and the unique knowledge gained from these diverse tools, with a focus on genome and systems-level approaches. We then describe ongoing synthetic biology approaches aimed at improving existing symbioses or engineering completely new symbiotic interactions. The review concludes with our perspective of the future directions and challenges of the field, with an emphasis on how the application of a multi-disciplinary approach and the development of new methods will be necessary to ensure successful biotechnological manipulation of the symbiosis.

RevDate: 2018-09-11

Kaur N, Cooper WR, Duringer JM, et al (2018)

Survival and development of potato psyllid (Hemiptera: Triozidae) on Convolvulaceae: Effects of a plant-fungus symbiosis (Periglandula).

PloS one, 13(9):e0201506 pii:PONE-D-18-20745.

Plant species in the family Solanaceae are the usual hosts of potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Psylloidea: Triozidae). However, the psyllid has also been shown to develop on some species of Convolvulaceae (bindweeds and morning glories). Developmental success on Convolvulaceae is surprising given the rarity of psyllid species worldwide associated with this plant family. We assayed 14 species of Convolvulaceae across four genera (Convolvulus, Calystegia, Ipomoea, Turbina) to identify species that allow development of potato psyllid. Two populations of psyllids were assayed (Texas, Washington). The Texas population overlaps extensively with native Convolvulaceae, whereas Washington State is noticeably lacking in Convolvulaceae. Results of assays were overlain on a phylogenetic analysis of plant species to examine whether Convolvulaceae distantly related to the typical host (potato) were less likely to allow development than species of Convolvulaceae more closely related. Survival was independent of psyllid population and location of the plant species on our phylogenetic tree. We then examined whether presence of a fungal symbiont of Convolvulaceae (Periglandula spp.) affected psyllid survival. These fungi associate with Convolvulaceae and produce a class of mycotoxins (ergot alkaloids) that may confer protection against plant-feeding arthropods. Periglandula was found in 11 of our 14 species, including in two genera (Convolvulus, Calystegia) not previously known to host the symbiont. Of these 11 species, leaf tissues from five contained large quantities of two classes of ergot alkaloids (clavines, amides of lysergic acid) when evaluated by LC-MS/MS. All five species also harbored Periglandula. No ergot alkaloids were detected in species free of the fungal symbiont. Potato psyllid rapidly died on the five species that harbored Periglandula and contained ergot alkaloids, but survived to adulthood on seven of the nine species in which ergot alkaloids were not detected. These results support the hypothesis that a plant-fungus symbiotic relationship affects the suitability of certain Convolvulaceae to potato psyllid.

RevDate: 2018-09-11

Ghodhbane-Gtari F, Nouioui I, Hezbri K, et al (2018)

The plant-growth-promoting actinobacteria of the genus Nocardia induces root nodule formation in Casuarina glauca.

Antonie van Leeuwenhoek pii:10.1007/s10482-018-1147-0 [Epub ahead of print].

Actinorhizal plants form a symbiotic association with the nitrogen-fixing actinobacteria Frankia. These plants have important economic and ecological benefits including land reclamation, soil stabilization, and reforestation. Recently, many non-Frankia actinobacteria have been isolated from actinorhizal root nodules suggesting that they might contribute to nodulation. Two Nocardia strains, BMG51109 and BMG111209, were isolated from Casuarina glauca nodules, and they induced root nodule-like structures in original host plant promoting seedling growth. The formed root nodule-like structures lacked a nodular root at the apex, were not capable of reducing nitrogen and had their cortical cells occupied with rod-shaped Nocardiae cells. Both Nocardia strains induced root hair deformation on the host plant. BMG111209 strain induced the expression of the ProCgNin:Gus gene, a plant gene involved in the early steps of the infection process and nodulation development. Nocardia strain BMG51109 produced three types of auxins (Indole-3-acetic acid [IAA], Indole-3-Byturic Acid [IBA] and Phenyl Acetic Acid [PAA]), while Nocardia BMG111209 only produced IAA. Analysis of the Nocardia genomes identified several important predicted biosynthetic gene clusters for plant phytohormones, secondary metabolites, and novel natural products. Co-infection studies showed that Nocardia strain BMG51109 plays a role as a "helper bacteria" promoting an earlier onset of nodulation. This study raises many questions on the ecological significance and functionality of Nocardia bacteria in actinorhizal symbioses.

RevDate: 2018-09-11

Bizarria R, Moia IC, Montoya QV, et al (2018)

Soluble Compounds of Filamentous Fungi Harm the Symbiotic Fungus of Leafcutter Ants.

Current microbiology pii:10.1007/s00284-018-1566-1 [Epub ahead of print].

Chemical compounds are key to understand symbiotic interactions. In the leafcutter ant-microbe symbiosis a plethora of filamentous fungi continuously gain access the ant colonies through plant substrate collected by workers. Many filamentous fungi are considered transient in attine ant colonies, however, their real ecological role in this environment still remains unclear. A possible role of these microorganisms is the antagonism towards Leucoagaricus gongylophorus, the mutualistic fungus that serve as food for several leafcutter ant species. Here, we showed the antagonism of filamentous fungi isolated from different sources, and the negative impacts of their metabolites on the growth of the ant-fungal cultivar. Our results demonstrate that the chemical compounds produced by filamentous fungi can harm the mutualistic fungus of leafcutter ants.

RevDate: 2018-09-11

Su Y, Zhou Z, X Yu (2018)

Possible roles of glutamine synthetase in responding to environmental changes in a scleractinian coral.

Molecular biology reports pii:10.1007/s11033-018-4369-3 [Epub ahead of print].

Glutamine synthetase is an enzyme that plays an essential role in the metabolism of nitrogen by catalyzing the condensation of glutamate and ammonia to form glutamine. In this study, the activity and responses of glutamine synthetase towards environmental changes were investigated in the scleractinian coral Pocillopora damicornis. The identified glutamine synthetase (PdGS) was comprised of 362 amino acids and predicted to contain one Gln-synt_N and one Gln-synt_C domain. Expression of PdGS mRNA increased significantly after 12 h (1.28-fold, p < 0.05) of exposure to elevated ammonium, while glutamine synthetase activity increased significantly from 12 to 24 h, peaking at 12 h (54.80 U mg-1, p < 0.05). The recombinant protein of the mature PdGS (rPdGS) was expressed in E. coli BL21, and its activities were detected under different temperature, pH and glufosinate levels. The highest levels of rPdGS activity were observed at 25 °C and pH 8 respectively, but decreased significantly at lower temperature, and higher or lower pH. Furthermore, the level of rPdGS activities was negatively correlated with the concentration of glufosinate, specifically decreasing at 10-5 mol L-1 glufosinate to be less than 50% (p < 0.05) of that in the blank. These results collectively suggest that PdGS, as a homologue of glutamine synthetase, was involved in the nitrogen assimilation in the scleractinian coral. Further, its physiological functions could be suppressed by high temperature, ocean acidification and residual glufosinate, which might further regulate the coral-zooxanthella symbiosis via the nitrogen metabolism in the scleractinian coral P. damicornis.

RevDate: 2018-09-11
CmpDate: 2018-09-11

Jandér KC, Dafoe A, EA Herre (2016)

Fitness reduction for uncooperative fig wasps through reduced offspring size: a third component of host sanctions.

Ecology, 97(9):2491-2500.

Mutually beneficial interactions between two species-mutualisms-are ancient, diverse, and of fundamental ecological importance. Nonetheless, factors that prevent one partner from reaping the benefits of the interaction without paying the cost are still poorly understood. Fig trees and their unique pollinators, fig wasps, present a powerful model system for studying mutualism stability. Both partners depend completely on each other for reproduction, cooperation levels can be manipulated, and the resulting field-based fitness quantified. Previous work has shown that fig trees can impose two types of host sanctions that reduce the fitness of wasps that do not pollinate: (1) fig abortion, which kills all developing larvae, and (2) reduced number of wasp offspring in figs that are not aborted. Here we demonstrate a third component of host sanctions. Through manipulative field experiments, we show that for four of five studied species, offspring of pollen-free foundresses are only 50-90% the size of offspring of pollinating foundresses. We further show that in all four studied species, smaller wasps are less likely to reach and enter a flowering fig to become foundresses themselves. Therefore, the experimentally determined size reduction of offspring is estimated to cause an additional reduction of up to 80% in fitness for a pollen-free foundress. We determine that the size reduction of pollen-free offspring acts on the level of the entire fig fruit rather than on individual flowers. These results show that estimates of the fitness effect of host sanctions on uncooperative symbionts should consider not only offspring quantity but also offspring quality. We discuss implications beyond the fig tree-fig wasp mutualism.

RevDate: 2018-09-11
CmpDate: 2018-09-11

Shaw WR, Marcenac P, Childs LM, et al (2016)

Wolbachia infections in natural Anopheles populations affect egg laying and negatively correlate with Plasmodium development.

Nature communications, 7:11772 pii:ncomms11772.

The maternally inherited alpha-proteobacterium Wolbachia has been proposed as a tool to block transmission of devastating mosquito-borne infectious diseases like dengue and malaria. Here we study the reproductive manipulations induced by a recently identified Wolbachia strain that stably infects natural mosquito populations of a major malaria vector, Anopheles coluzzii, in Burkina Faso. We determine that these infections significantly accelerate egg laying but do not induce cytoplasmic incompatibility or sex-ratio distortion, two parasitic reproductive phenotypes that facilitate the spread of other Wolbachia strains within insect hosts. Analysis of 221 blood-fed A. coluzzii females collected from houses shows a negative correlation between the presence of Plasmodium parasites and Wolbachia infection. A mathematical model incorporating these results predicts that infection with these endosymbionts may reduce malaria prevalence in human populations. These data suggest that Wolbachia may be an important player in malaria transmission dynamics in Sub-Saharan Africa.

RevDate: 2018-08-16
CmpDate: 2018-08-16

Lin Z, Zu XP, Xie HS, et al (2016)

[Research progress in mechanism of intestinal microorganisms in human diseases].

Yao xue xue bao = Acta pharmaceutica Sinica, 51(6):843-852.

The international cooperated research projects of the Human Microbiome Project (HMP) and Metagenomics of The Human Intestinal Tract (MetaHIT) were officially launched in 2007, which indicated the era of metagenomics research of microorganisms in human gastrointestinal tract had been coming. Each human body is a superorganism which is composed of 90% commensal microorganisms, especially the intestinal microorganisms. The intestinal microorganisms play an important role on health maintenance since they are involved in the absorption and metabolism of nutrients in the human bodies. Herein, we review the research progress in the mechanism of intestinal microorganisms in human diseases. Our purpose is to provide novel ideas on human health and therapeutic targets of diseases.

RevDate: 2018-09-10

Yang X, Hu Q, Han Z, et al (2018)

Effects of exogenous microbial inoculum on the structure and dynamics of bacterial communities in swine carcass composting.

Canadian journal of microbiology [Epub ahead of print].

Composting is a widely accepted method for the disposal of deceased livestock. Composting is a biological self-heating process, during which animal carcasses are converted to fertilizer products. Additional inoculants can facilitate the composting progress. This study investigated how the addition of microbial inocula can improve the composting effectiveness and change the structure and dynamics of bacterial communities in the carcass composting process. Inoculants comprised of four Bacillus strains were inoculated into the swine carcass composting piles. The groups with the additional inocula showed higher temperatures in the thermophilic phase and higher germination indices in the composted products. The sequencing results showed that the dominant phyla were Proteobacteria, Firmicutes and Actinobacteria, and the dominant classified genera were Brevibacterium and Bacillus. Canonical correlation analysis showed that temperature and moisture exerted a stronger influence on the bacterial community diversity. The interaction network of dominant genera and the abundance variation of the bacterial community demonstrated that the inoculant bacterial agent changed the structure of bacterial communities and enriched the diversity of the species due to antagonism and symbiosis among the dominant bacterial communities.

RevDate: 2018-09-10

Bachman BA, Kraus RT, Peterson CT, et al (2018)

Growth and reproduction of Echeneis naucrates from the eastern Gulf of Mexico.

Journal of fish biology [Epub ahead of print].

This study describes growth and reproductive characteristics of a facultative elasmobranch symbiont, the sharksucker (remora) Echeneis naucrates, from the eastern Gulf of Mexico. Females grew slower but achieved a larger size than males and host-symbiont length ratios increased linearly with E. naucrates length Mean relative batch fecundity was 39.5 hydrated oocytes g-1 of ovary-free body mass, but gonad histology samples from August were inconclusive regarding total annual fecundity and timing of gonad development.

RevDate: 2018-09-10

Igiehon NO, OO Babalola (2018)

Below-ground-above-ground Plant-microbial Interactions: Focusing on Soybean, Rhizobacteria and Mycorrhizal Fungi.

The open microbiology journal, 12:261-279 pii:TOMICROJ-12-261.

Introduction: Organisms seldom exist in isolation and are usually involved in interactions with several hosts and these interactions in conjunction with the physicochemical parameters of the soil affect plant growth and development. Researches into below and aboveground microbial community are unveiling a myriad of intriguing interactions within the rhizosphere, and many of the interactions are facilitated by exudates that are secreted by plants roots. These interactions can be harnessed for beneficial use in agriculture to enhance crop productivity especially in semi-arid and arid environments.

The Rhizosphere: The rhizosphere is the region of soil close to plants roots that contain large number of diverse organisms. Examples of microbial candidates that are found in the rhizosphere include the Arbuscular Mycorrhizal Fungi (AMF) and rhizobacteria. These rhizosphere microorganisms use plant root secretions such as mucilage and flavonoids which are able to influence their diversity and function and also enhance their potential to colonize plants root.

In the natural environments, plants live in interactions with different microorganisms, which thrive belowground in the rhizosphere and aboveground in the phyllosphere. Some of the plant-microbial interactions (which can be in the form of antagonism, amensalism, parasitism and symbiosis) protect the host plants against detrimental microbial and non-microbial invaders and provide nutrients for plants while others negatively affect plants. These interactions can influence below-ground-above-ground plants' biomass development thereby playing significant role in sustaining plants. Therefore, understanding microbial interactions within the rhizosphere and phyllosphere is urgent towards farming practices that are less dependent on conventional chemical fertilizers, which have known negative impacts on the environments.

Drought stress is one of the major factors militating against agricultural productivity globally and is likely to further increase. Belowground rhizobacteria interactions could play important role in alleviating drought stress in plants. These beneficial rhizobacterial colonize the rhizosphere of plants and impart drought tolerance by up regulation or down regulation of drought responsive genes such as ascorbate peroxidase, S-adenosyl-methionine synthetase, and heat shock protein.

Investigating complex microbial community in the environment is a big challenge. Therefore, omic studies of microorganisms that inhabit the rhizosphere are important since this is where most plant-microbial interactions occur. One of the aims of this review is not to give detailed account of all the present omic techniques, but instead to highlight the current omic techniques that can possibly lead to detection of novel genes and their respective proteins within the rhizosphere which may be of significance in enhancing crop plants (such as soybean) productivity especially in semi-arid and arid environments.

Plant-microbial interactions are not totally understood, and there is, therefore, the need for further studies on these interactions in order to get more insights that may be useful in sustainable agricultural development. With the emergence of omic techniques, it is now possible to effectively monitor transformations in rhizosphere microbial community together with their effects on plant development. This may pave way for scientists to discover new microbial species that will interact effectively with plants. Such microbial species can be used as biofertilizers and/or bio-pesticides to increase crop yield and enhance global food security.

RevDate: 2018-09-10

Al-Khafaji AM, Clegg SR, Pinder AC, et al (2018)

Multi-locus sequence typing of Ixodes ricinus and its symbiont Candidatus Midichloria mitochondrii across Europe reveals evidence of local co-cladogenesis in Scotland.

Ticks and tick-borne diseases pii:S1877-959X(18)30078-5 [Epub ahead of print].

Ticks have relatively complex microbiomes, but only a small proportion of the bacterial symbionts recorded from ticks are vertically transmitted. Moreover, co-cladogenesis between ticks and their symbionts, indicating an intimate relationship over evolutionary history driven by a mutualistic association, is the exception rather than the rule. One of the most widespread tick symbionts is Candidatus Midichloria, which has been detected in all of the major tick genera of medical and veterinary importance. In some species of Ixodes, such as the sheep tick Ixodes ricinus (infected with Candidatus Midichloria mitochondrii), the symbiont is fixed in wild adult female ticks, suggesting an obligate mutualism. However, almost no information is available on genetic variation in Candidatus M. mitochondrii or possible co-cladogenesis with its host across its geographic range. Here, we report the first survey of Candidatus M. mitochondrii in I. ricinus in Great Britain and a multi-locus sequence typing (MLST) analysis of tick and symbiont between British ticks and those collected in continental Europe. We show that while the prevalence of the symbiont in nymphs collected in England is similar to that reported from the continent, a higher prevalence in nymphs and adult males is apparent in Wales. In general, Candidatus M. mitochondrii exhibits very low levels of sequence diversity, although a consistent signal of host-symbiont coevolution was apparent in Scotland. Moreover, the tick MLST scheme revealed that Scottish specimens form a clade that is partially separated from other British ticks, with almost no contribution of continental sequence types in this north-westerly border of the tick's natural range. The low diversity of Candidatus M. mitochondrii, in contrast with previously reported high rates of polymorphism in I. ricinus mitogenomes, suggests that the symbiont may have swept across Europe recently via a horizontal, rather than vertical, transmission route.

RevDate: 2018-09-09

Matiiv AB, EM Chekunova (2018)

Aureochromes - Blue Light Receptors.

Biochemistry. Biokhimiia, 83(6):662-673.

A variety of living organisms including bacteria, fungi, animals, and plants use blue light (BL) to adapt to changing ambient light. Photosynthetic forms (plants and algae) require energy of light for photosynthesis, movements, development, and regulation of activity. Several complex light-sensitive systems evolved in eukaryotic cells to use the information of light efficiently with photoreceptors selectively absorbing various segments of the solar spectrum, being the first components in the light signal transduction chain. They are most diverse in algae. Photosynthetic stramenopiles, which received chloroplasts from red algae during secondary symbiosis, play an important role in ecosystems and aquaculture, being primary producers. These taxa acquired the ability to use BL for regulation of such processes as phototropism, chloroplast photo-relocation movement, and photomorphogenesis. A new type of BL receptor - aureochrome (AUREO) - was identified in Vaucheria frigida in 2007. AUREO consists of two domains: bZIP (basic-region leucine zipper) domain and LOV (light-oxygen-voltage-sensing) domain, and thus this photoreceptor is a BL-sensitive transcription factor. This review presents current data on the structure, mechanisms of action, and biochemical features of aureochromes.

RevDate: 2018-09-07

Ratib NR, Sabio EY, Mendoza C, et al (2018)

Genome-wide identification of genes directly regulated by ChvI and a consensus sequence for ChvI binding in Sinorhizobium meliloti.

Molecular microbiology [Epub ahead of print].

ExoS/ChvI two-component signaling in the nitrogen-fixing α-proteobacterium Sinorhizobium meliloti is required for symbiosis and regulates exopolysaccharide production, motility, cell envelope integrity, and nutrient utilization in free-living bacteria. However, identification of many ExoS/ChvI direct transcriptional target genes has remained elusive. Here, we performed chromatin immunoprecipitation followed by microarray analysis (chIP-chip) to globally identify DNA regions bound by ChvI protein in S. meliloti. We then performed qRT-PCR with chvI mutant strains to test ChvI-dependent expression of genes downstream of the ChvI-bound DNA regions. We identified 64 direct target genes of ChvI, including exoY, rem, and chvI itself. We also identified ChvI direct target candidates, like exoR, that are likely controlled by additional regulators. Analysis of upstream sequences from the 64 ChvI direct target genes identified a 15 bp-long consensus sequence. Using electrophoretic mobility shift assays and transcriptional fusions with exoY, SMb21440, SMc00084, SMc01580, chvI, and ropB1, we demonstrated this consensus sequence is important for ChvI binding to DNA and transcription of ChvI direct target genes. Thus, we have comprehensively identified ChvI regulon genes and a "ChvI box" bound by ChvI. Many ChvI direct target genes may influence the cell envelope, consistent with the critical role of ExoS/ChvI in growth and microbe-host interactions. This article is protected by copyright. All rights reserved.

RevDate: 2018-08-22
CmpDate: 2018-08-22

Thomas T, Moitinho-Silva L, Lurgi M, et al (2016)

Diversity, structure and convergent evolution of the global sponge microbiome.

Nature communications, 7:11870 pii:ncomms11870.

Sponges (phylum Porifera) are early-diverging metazoa renowned for establishing complex microbial symbioses. Here we present a global Porifera microbiome survey, set out to establish the ecological and evolutionary drivers of these host-microbe interactions. We show that sponges are a reservoir of exceptional microbial diversity and major contributors to the total microbial diversity of the world's oceans. Little commonality in species composition or structure is evident across the phylum, although symbiont communities are characterized by specialists and generalists rather than opportunists. Core sponge microbiomes are stable and characterized by generalist symbionts exhibiting amensal and/or commensal interactions. Symbionts that are phylogenetically unique to sponges do not disproportionally contribute to the core microbiome, and host phylogeny impacts complexity rather than composition of the symbiont community. Our findings support a model of independent assembly and evolution in symbiont communities across the entire host phylum, with convergent forces resulting in analogous community organization and interactions.

RevDate: 2018-09-06

Ross BJ, P Hallock (2018)

Challenges in using CellTracker Green on foraminifers that host algal endosymbionts.

PeerJ, 6:e5304 pii:5304.

The uses of fluorescent microscopy and fluorescent probes, such as the metabolically activated probe CellTracker™ Green CMFDA (CTG), have become common in studies of living Foraminifera. This metabolic requirement, as well as the relatively quick production of the fluorescent reaction products, makes CTG a prime candidate for determining mortality in bioassay and other laboratory experiments. Previous work with the foraminifer Amphistegina gibbosa, which hosts diatom endosymbionts, has shown that the species is capable of surviving both acute chemical exposure and extended periods of total darkness by entering a low-activity dormant state. This paper explores the use of CTG and fluorescent microscopy to determine mortality in such experiments, as well as to explore the physiology of dormant foraminifers. The application of CTG was found to be complicated by the autofluorescence of the diatom symbionts, which masks the signal of the CTG, as well as by interactions between CTG and propylene glycol, a chemical of interest known to cause dormancy. These complications necessitated adapting methods from earlier studies using CTG. Here we present observations on CTG fluorescence and autofluorescence in A. gibbosa following both chemical exposure and periods of total darkness. While CTG can indicate vital activity in dormant foraminifers, complications include underestimates of total survival and recovery, and falsely indicating dead individuals as live due to rapid microbial colonization. Nonetheless, the brightness of the CTG signal in dormant individuals exposed to propylene glycol supports previously published results of survival patterns in A. gibbosa. Observations of CTG fluorescence in individuals kept for extended periods in aphotic conditions indicate uptake of CTG may begin within 30 min of exposure to light, suggesting darkness-induced dormancy and subsequent recovery can occur on short time scales. These results suggest that CTG accurately reflects changes associated with dormancy, and can be useful in laboratory experiments utilizing symbiont-bearing foraminifers.

RevDate: 2018-09-06

Tena G (2018)

Slimy symbiosis.

Nature plants, 4(9):629.

RevDate: 2018-09-06

Giram PS, Shitole A, Nande SS, et al (2018)

Fast dissolving moxifloxacin hydrochloride antibiotic drug from electrospun Eudragit L-100 nonwoven nanofibrous Mats.

Materials science & engineering. C, Materials for biological applications, 92:526-539.

Antimicrobial electrospun nonwoven Eudragit L-100 nanofibrous mats containing Moxifloxacin hydrochloride (MOX-HCL) were fabricated for fast dissolving drug delivery systems (DDSs) associated with wound infection. The morphological characterization of nanofibers using ESEM revealed that the average diameter of non-woven nanofibrous mats ranges 200-600 nm. The nanofiber showed cylindrical shape with crack on the surface. Differential scanning calorimetric (DSC) and Wide Angle X-ray diffraction (WAXRD) demonstrate that the drug exists in an amorphous state in the nanofibers. Nanofibrous mats were also tested for mechanical strength, contact angle, swelling assay, haemolysis and disintegration test. In vitro disintegration tests demonstrated that the dissolution of Eudragit L-100 fiber mats was within 25 s which was higher compared to the pure drug. The Eudragit nanofibers showed pH-dependent drug release profiles, with slow release at pH 1.2 and burst release (around 30 s) at pH 6.8. The in-vitro quantitative and qualitative antimicrobial assay showed that the developed Eudragit L-100 nanofibrous mats with MOX-HCL concentration of 1%, 5% and 15 wt% exhibited antibacterial activities against both gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria. The in-vitro cytotoxicity assay using mouse fibroblast NIH/3T3 cells demonstrated significant biocompatibility of nanofiber mats. As per the results of biological evaluation, Eudragit L-100 nanofibrous mats with 1wt% MOX-HCL could be a suitable substrate for biomedical applications. Eudragit L-100 nanofibrous mats containing Moxifloxacin hydrochloride (MOX-HCL) showed immediate DDSs for localized drug release in the wound infection at slightly acidic or alkaline conditions where faster drug release rate is required for wound healing.

RevDate: 2018-09-05

Nouioui I, Ghodhbane-Gtari F, Rhode M, et al (2018)

Frankia irregularis sp. nov., an actinobacterium unable to nodulate its original host, Casuarina equisetifolia, but effectively nodulates members of the actinorhizal Rhamnales.

International journal of systematic and evolutionary microbiology, 68(9):2883-2914.

A red pigmented actinobacterium designated G2T, forming extremely branched vegetative hyphae, vesicles and mutilocular sporangia, was isolated from Casuarina equisetifolia nodules. The strain failed to nodulate its original host plant but effectively nodulated members of actinorhizal Rhamnales. The taxonomic position of G2T was determined using a polyphasic approach. The peptidoglycan of the strain contained meso-diaminopimelic acid as diagnostic diamino acid, galactose, glucose, mannose, rhamnose, ribose and xylose. The polar lipid pattern consisted of phosphatidylinositol (PI), diphosphatidylglycerol (DPG), glycophospholipids (GPL1-2), phosphatidylglycerol (PG), aminophospholipid (APL) and unknown lipids (L). The predominant menaquinones were MK-9 (H4) and MK-9 (H6) while the major fatty acids were iso-C16 : 0, C17 : 1ω8c and C15 : 0. The size of the genome of G2T was 9.5 Mb and digital DNA G+C content was 70.9 %. The 16S rRNA gene showed 97.4-99.5 % sequence identity with the type strains of species of the genus Frankia. Digital DNA -DNA hybridisation (dDDH) values between G2T and its nearest phylogenetic neighbours Frankia elaeagniand Frankia discariaewere below the threshold of 70 %. On the basis of these results, strain G2T (=DSM 45899T=CECT 9038T) is proposed to represent the type strain of a novel species Frankia irregularis sp. nov.

RevDate: 2018-09-05
CmpDate: 2018-09-05

Lee DW, I Hwang (2018)

Evolution and Design Principles of the Diverse Chloroplast Transit Peptides.

Molecules and cells, 41(3):161-167.

Chloroplasts are present in organisms belonging to the kingdom Plantae. These organelles are thought to have originated from photosynthetic cyanobacteria through endosymbiosis. During endosymbiosis, most cyanobacterial genes were transferred to the host nucleus. Therefore, most chloroplast proteins became encoded in the nuclear genome and must return to the chloroplast after translation. The N-terminal cleavable transit peptide (TP) is necessary and sufficient for the import of nucleus-encoded interior chloroplast proteins. Over the past decade, extensive research on the TP has revealed many important characteristic features of TPs. These studies have also shed light on the question of how the many diverse TPs could have evolved to target specific proteins to the chloroplast. In this review, we summarize the characteristic features of TPs. We also highlight recent advances in our understanding of TP evolution and provide future perspectives about this important research area.

RevDate: 2018-09-05
CmpDate: 2018-09-05

Zhou A, Qu X, Shan L, et al (2017)

Temperature warming strengthens the mutualism between ghost ants and invasive mealybugs.

Scientific reports, 7(1):959 pii:10.1038/s41598-017-01137-0.

Although the exogenous forces that directly affect the mutualisms between ants and honeydew-producing hemipterans have been well documented, few studies have been focused on the impacts of environmental warming on ant-hemipteran interactions. Here, we investigated how temperature warming affects the mutualism between ghost ant Tapinoma melanocephalum and invasive mealybug Phenacoccus solenopsis by experimental manipulation of temperature. We found that higher temperatures have significant direct effects on the growth rate of mealybug colony, and the positive effect of ant tending on mealybug colony growth is temperature-dependent. Honeydew excretion by mealybugs was affected by ant tending and temperature warming, and was significantly increased under higher temperature. The effect of ant tending on percentage parasitism was also influenced by temperature warming. Ant performance including tending level, aggression, activity, and honeydew consumption was enhanced by temperature warming, which may provide superior protection to the mealybugs. Our results show that ghost ant-mealybug mutualism is strengthened in a warmer environment. These findings may facilitate the prediction of how each partner in the ant-hemipteran-enemy interactions responds to increasing temperature.

RevDate: 2018-09-05
CmpDate: 2018-09-05

Dunning Hotopp JC, Slatko BE, JM Foster (2017)

Targeted Enrichment and Sequencing of Recent Endosymbiont-Host Lateral Gene Transfers.

Scientific reports, 7(1):857 pii:10.1038/s41598-017-00814-4.

Lateral gene transfer (LGT) from microbial symbionts to invertebrate animals is described at an increasing rate, particularly between Wolbachia endosymbionts and their diverse invertebrate hosts. We sought to assess the use of a capture system to cost-effectively sequence such LGT from the host genome. The sequencing depth of Illumina paired end data obtained with a Wolbachia capture system correlated well with that for an Illumina paired end data set used to detect LGT in Wolbachia-depleted B. malayi (p-value: <2e-16). Using a sequencing depth threshold of two or three standard deviations above the mean, 96.9% or 96.7% of positions, respectively, are predicted in the same manner between the two datasets, with 24.7% or 42.5% of the known 49.0 kbp of LGT sequence predicted correctly, respectively. Prior qPCR results for nuwts showed similar correlations for both datasets supporting our conclusion that oligonucleotide-based capture methods can be used to obtain sequences from Wolbachia-host LGT. However, at least 121 positions had a minority of the reads supporting the endosymbiont reference base call using the capture data, illustrating that sequence reads from endosymbiont-host LGTs can confound endosymbiont genome projects, erroneously altering the called consensus genome, a problem that is irrespective to the sequencing technology or platform.

RevDate: 2018-09-05
CmpDate: 2018-09-05

Toro N, Villadas PJ, Molina-Sánchez MD, et al (2017)

The underlying process of early ecological and genetic differentiation in a facultative mutualistic Sinorhizobium meliloti population.

Scientific reports, 7(1):675 pii:10.1038/s41598-017-00730-7.

The question of how genotypic and ecological units arise and spread in natural microbial populations remains controversial in the field of evolutionary biology. Here, we investigated the early stages of ecological and genetic differentiation in a highly clonal sympatric Sinorhizobium meliloti population. Whole-genome sequencing revealed that a large DNA region of the symbiotic plasmid pSymB was replaced in some isolates with a similar synteny block carrying densely clustered SNPs and displaying gene acquisition and loss. Two different versions of this genomic island of differentiation (GID) generated by multiple genetic exchanges over time appear to have arisen recently, through recombination in a particular clade within this population. In addition, these isolates display resistance to phages from the same geographic region, probably due to the modification of surface components by the acquired genes. Our results suggest that an underlying process of early ecological and genetic differentiation in S. meliloti is primarily triggered by acquisition of genes that confer resistance to soil phages within particular large genomic DNA regions prone to recombination.

RevDate: 2018-09-05
CmpDate: 2018-09-05

Farag MA, Al-Mahdy DA, Meyer A, et al (2017)

Metabolomics reveals biotic and abiotic elicitor effects on the soft coral Sarcophyton ehrenbergi terpenoid content.

Scientific reports, 7(1):648 pii:10.1038/s41598-017-00527-8.

The effects of six biotic and abiotic elicitors, i.e. MeJA (methyl jasmonate), SA (salicylic acid), ZnCl2, glutathione and β-glucan BG (fungal elicitor), and wounding, on the secondary metabolite accumulation in the soft coral Sarcophyton ehrenbergi were assessed. Upon elicitation, metabolites were extracted and analysed by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Except for MeJA, no differences in photosynthetic efficiency were observed after treatments, suggesting the absence of a remarkable stress on primary production. Chemometric analyses of UPLC-MS data showed clear segregation of SA and ZnCl2 elicited samples at 24 and 48 h post elicitation. Levels of acetylated diterpene and sterol viz., sarcophytonolide I and cholesteryl acetate, was increased in ZnCl2 and SA groups, respectively, suggesting an activation of specific acetyl transferases. Post elicitation, sarcophytonolide I level increased 132 and 17-folds at 48 h in 0.1 mM SA and 1 mM ZnCl2 groups, respectively. Interestingly, decrease in sarcophine, a major diterpene was observed only in response to ZnCl2, whereas no change was observed in sesquiterpene content following treatments. To the best of our knowledge, this study provides the first documentation for elicitation effects on a soft corals secondary metabolome and suggests that SA could be applied to increase diterpenoid levels in corals.

RevDate: 2018-09-05
CmpDate: 2018-09-05

Mira A, Simon-Soro A, MA Curtis (2017)

Role of microbial communities in the pathogenesis of periodontal diseases and caries.

Journal of clinical periodontology, 44 Suppl 18:S23-S38.

The microbiological characteristics of both caries and periodontal disease show significant change from those in health. In both instances, there is evidence of co-association of different organisms into consortia.

AIM: We review and summarize a number of issues pertinent to the community organization and functional activity of the bacterial populations resident on supra- and subgingival tooth surface and the influence of these populations on disease.

METHODS: A literature review was undertaken with a particular emphasis on recent publications involving high-throughput, deep sequencing approaches to the analysis of microbial populations and their functional activity.

RESULTS: There is increasing evidence to suggest that both caries and periodontal disease represent dysbiotic states of the oral microbiome. The mode of acquisition of the oral microbial communities may be less passive than previously recognized but once established remains relatively stable within an individual although there are very significant site variations. A repertoire of stable dysbiotic states may occur in both caries and periodontitis involving different microbial community structures with potentially similar functional properties.

CONCLUSIONS: The processes which underlie the development and stability of microbial populations in the healthy mouth are fundamental to understanding how these populations are transformed into a dysbiotic state in disease.

RevDate: 2018-09-04

Tiwari R, Negandhi H, SP Zodpey (2018)

Health Management Workforce for India in 2030.

Frontiers in public health, 6:227.

Introduction: Since its launch in the year 2005, National Rural Health Mission (NHM) has exhibited a felt need for health management training in India against the background of a shortfall of trained public health managers in the country. In India's context, health (hospital) management professionals are those, who are working in the health sector, belonging to medical and non-medical backgrounds and are trained in health (hospital) management/administration programs or other public health programs (for e.g., Master of Public Health) wherein health (hospital) management/administration is significant part of the curriculum. The presence of trained management professionals in the health sector has grown over the years. Objectives: To estimate the supply, need and requirement for health management professionals for India in the year 2030. Materials and methods: The supply data for health management professionals was calculated based on the output from various academic programs related to health management/administration and other public health programs. Need was calculated using "service target approach" and benchmark analysis with 2.97 health managers per 100,000 population (NACCHO 2011). Supply-need gap was estimated using normative need as base number for projections whereas for rest of the years (2018-2030) projections were done at a constant growth rate as per India's population projections. Results: The overall supply capacity of trained health management professionals was 3,463 for 2017. However, based upon a service target approach India requires 11,304 health management professionals in 2017. If India is to reach the normative standards of 2.97 health managers per 100,000 population, the country would need 39,774 health management professionals in 2017. This need would increase to approximately 44,936 health management professionals by the year 2030 to maintain the normative standard of 2.97 health managers per 100,000 population. Conclusions: The supply side will match the requirement of HMPs earliest by the year 2026 in a high seat occupancy scenario.Moreover, there is a need to improve the quality of the output in terms of an explicitly stated and standardized competency framework that is tailored to the Indian context.

RevDate: 2018-09-04

Kelly S, Mun T, Stougaard J, et al (2018)

Distinct Lotus japonicus Transcriptomic Responses to a Spectrum of Bacteria Ranging From Symbiotic to Pathogenic.

Frontiers in plant science, 9:1218.

Lotus japonicus is a well-studied nodulating legume and a model organism for the investigation of plant-microbe interactions. The majority of legume transcriptome studies have focused on interactions with compatible symbionts, whereas responses to non-adapted rhizobia and pathogenic bacteria have not been well-characterized. In this study, we first characterized the transcriptomic response of L. japonicus to its compatible symbiont, Mesorhizobium loti R7A, through RNA-seq analysis of various plant tissues. Early symbiotic signaling was largely Nod factor-dependent and enhanced within root hairs, and we observed large-scale transcriptional reprogramming in nodule primordia and mature nitrogen-fixing nodules. We then characterized root transcriptional responses to a spectrum of L. japonicus interacting bacteria ranging from semi-compatible symbionts to pathogens. M. loti R7A and the semi-compatible strain Sinorhizobium fredii HH103 showed remarkably similar responses, allowing us to identify a small number of genes potentially involved in differentiating between fully and semi-compatible symbionts. The incompatible symbiont Bradyrhizobium elkanii USDA61 induced a more attenuated response, but the weakest response was observed for the foliar pathogen Pseudomonas syringae pv. tomato DC3000, where the affected genes also responded to other tested bacteria, pointing to a small set of common bacterial response genes. In contrast, the root pathogen Ralstonia solanacearum JS763 induced a pronounced and distinct transcriptomic pathogen response, which we compared to the results of the other treatments. This comparative analysis did not support the concept that an early defense-like response is generally evoked by compatible rhizobia during establishment of symbiosis.

RevDate: 2018-09-04
CmpDate: 2018-09-04

Tan CW, Peiffer M, Hoover K, et al (2018)

Symbiotic polydnavirus of a parasite manipulates caterpillar and plant immunity.

Proceedings of the National Academy of Sciences of the United States of America, 115(20):5199-5204.

Obligate symbioses occur when organisms require symbiotic relationships to survive. Some parasitic wasps of caterpillars possess obligate mutualistic viruses called "polydnaviruses." Along with eggs, wasps inject polydnavirus inside their caterpillar hosts where the hatching larvae develop inside the caterpillar. Polydnaviruses suppress the immune systems of their caterpillar hosts, which enables egg hatch and wasp larval development. It is unknown whether polydnaviruses also manipulate the salivary proteins of the caterpillar, which may affect the elicitation of plant defenses during feeding by the caterpillar. Here, we show that a polydnavirus of the parasitoid Microplitis croceipes, and not the parasitoid larva itself, drives the regulation of salivary enzymes of the caterpillar Helicoverpa zea that are known to elicit tomato plant-defense responses to herbivores. The polydnavirus suppresses glucose oxidase, which is a primary plant-defense elicitor in the saliva of the H. zea caterpillar. By suppressing plant defenses, the polydnavirus allows the caterpillar to grow at a faster rate, thus improving the host suitability for the parasitoid. Remarkably, polydnaviruses manipulate the phenotypes of the wasp, caterpillar, and host plant, demonstrating that polydnaviruses play far more prominent roles in shaping plant-herbivore interactions than ever considered.

RevDate: 2018-09-04
CmpDate: 2018-09-04

Zhu F, Cusumano A, Bloem J, et al (2018)

Symbiotic polydnavirus and venom reveal parasitoid to its hyperparasitoids.

Proceedings of the National Academy of Sciences of the United States of America, 115(20):5205-5210.

Symbiotic relationships may provide organisms with key innovations that aid in the establishment of new niches. For example, during oviposition, some species of parasitoid wasps, whose larvae develop inside the bodies of other insects, inject polydnaviruses into their hosts. These symbiotic viruses disrupt host immune responses, allowing the parasitoid's progeny to survive. Here we show that symbiotic polydnaviruses also have a downside to the parasitoid's progeny by initiating a multitrophic chain of interactions that reveals the parasitoid larvae to their enemies. These enemies are hyperparasitoids that use the parasitoid progeny as host for their own offspring. We found that the virus and venom injected by the parasitoid during oviposition, but not the parasitoid progeny itself, affected hyperparasitoid attraction toward plant volatiles induced by feeding of parasitized caterpillars. We identified activity of virus-related genes in the caterpillar salivary gland. Moreover, the virus affected the activity of elicitors of salivary origin that induce plant responses to caterpillar feeding. The changes in caterpillar saliva were critical in inducing plant volatiles that are used by hyperparasitoids to locate parasitized caterpillars. Our results show that symbiotic organisms may be key drivers of multitrophic ecological interactions. We anticipate that this phenomenon is widespread in nature, because of the abundance of symbiotic microorganisms across trophic levels in ecological communities. Their role should be more prominently integrated in community ecology to understand organization of natural and managed ecosystems, as well as adaptations of individual organisms that are part of these communities.

RevDate: 2018-09-04
CmpDate: 2018-09-04

Lagarde A, Jargeat P, Roy M, et al (2018)

Fungal communities associated with Evernia prunastri, Ramalina fastigiata and Pleurosticta acetabulum: Three epiphytic lichens potentially active against Candida biofilms.

Microbiological research, 211:1-12.

Fungal communities associated to three epiphytic lichens active against Candida, were investigated using culture-based methods We hypothetized that associated fungi would contribute to lichens activities. The ability of specific fungi to grow inside or outside lichens was investigated. To detect biogenesis pathways involved in the production of secondary metabolites, genes coding for nonribosomal peptide synthetase (NRPS) and polyketide synthase I (PKS I) were screened by PCR from fungal DNA extracts. Both endo and epilichenic communities were isolated from two fructicose (Evernia prunastri and Ramalina fastigiata) and one foliose (Pleurosticta acetabulum) lichens. A total of 86 endolichenic and 114 epilichenic isolates were obtained, corresponding to 18 and 24 phylogenetic groups respectively suggesting a wide diversity of fungi. The communities and the species richness were distinct between the three lichens which hosted potentially new fungal species. Additionally, the endo- and epilichenic communities differed in their composition: Sordariomycetes were particularly abundant among endolichenic fungi and Dothideomycetes among epilichenic fungi. Only a few fungi colonized both habitats, such as S. fimicola, Cladosporium sp1 and Botrytis cinerea. Interestingly, Nemania serpens (with several genotypes) was the most abundant endolichenic fungus (53% of isolates) and was shared by the three lichens. Finally, 12 out of 36 phylogenetic groups revealed the presence of genes coding for nonribosomal peptide synthetase (NRPs) and polyketide synthase I (PKS I). This study shows that common lichens are reservoirs of diverse fungal communities, which could potentially contribute to global activity of the lichen and, therefore, deserve to be isolated for further chemical studies.

RevDate: 2018-09-04
CmpDate: 2018-09-04

Radford L, Alexander S, S Waters (2018)

On the Rocks: Using Discourse Analysis to Examine Relationships between Barbary Macaques (Macaca sylvanus) and People on Gibraltar.

Folia primatologica; international journal of primatology, 89(1):30-44.

Primates are difficult to categorise due to some of the human-like characteristics they possess. Here, we examine the complexities that exist in a commensal relationship between an introduced population of Barbary macaques and local human populations on Gibraltar. In Western culture, much has been done to recognise primates' human characteristics while simultaneously focusing on keeping them at a metaphorical distance. In the context of Gibraltar's Barbary macaques, the anomalous status of primates causes a duality of perception whereby the macaques' position makes them both more frustrating and perceived as more worthy of protection. We examine the language used by Gibraltar residents about the macaques, interpreting statements using discourse analysis to reveal the complexities of people's perceptions of the macaques. Our results indicate that Barbary macaques on Gibraltar occupy a perceptual context of internal conflict in which they are viewed both with pride and a sense of ownership as well as with mistrust and fear. The relationship between people and Barbary macaques on Gibraltar is complex, and while sensitisation programmes and awareness-raising efforts exist, we recommend greater collaboration with residents to prevent the development of more intense negative human-macaque interactions.

RevDate: 2018-09-04
CmpDate: 2018-09-04

Morales-Linares J, García-Franco JG, Flores-Palacios A, et al (2018)

Orchid seed removal by ants in Neotropical ant-gardens.

Plant biology (Stuttgart, Germany), 20(3):525-530.

Most plants that inhabit ant-gardens (AGs) are cultivated by the ants. Some orchids occur in AGs; however, it is not known whether their seeds are dispersed by AG ants because most orchid seeds are tiny and dispersed by wind. We performed in situ seed removal experiments, in which we simultaneously provided Azteca gnava ants with seeds of three AG orchid species and three other AG epiphyte species (Bromeliaceae, Cactaceae and Gesneriaceae), as well as the non-AG orchid Catasetum integerrimum. The seeds most removed were those of the bromeliad Aechmea tillandsioides and the gesneriad Codonanthe uleana, while seeds of AG orchids Coryanthes picturata, Epidendrum flexuosum and Epidendrum pachyrachis were less removed. The non-AG orchid was not removed. Removal values were positively correlated with the frequency of the AG epiphytes in the AGs, and seeds of AG orchids were larger than those of non-AG orchids, which should favour myrmecochory. Our data show that Azt. gnava ants discriminate and preferentially remove seeds of the AG epiphytes. We report for the first time the removal of AG orchid seeds by AG ants in Neotropical AGs.

RevDate: 2018-09-04
CmpDate: 2018-09-04

Liao W, Menge DNL, Lichstein JW, et al (2017)

Global climate change will increase the abundance of symbiotic nitrogen-fixing trees in much of North America.

Global change biology, 23(11):4777-4787.

Symbiotic nitrogen (N)-fixing trees can drive N and carbon cycling and thus are critical components of future climate projections. Despite detailed understanding of how climate influences N-fixation enzyme activity and physiology, comparatively little is known about how climate influences N-fixing tree abundance. Here, we used forest inventory data from the USA and Mexico (>125,000 plots) along with climate data to address two questions: (1) How does the abundance distribution of N-fixing trees (rhizobial, actinorhizal, and both types together) vary with mean annual temperature (MAT) and precipitation (MAP)? (2) How will changing climate shift the abundance distribution of N-fixing trees? We found that rhizobial N-fixing trees were nearly absent below 15°C MAT, but above 15°C MAT, they increased in abundance as temperature rose. We found no evidence for a hump-shaped response to temperature throughout the range of our data. Rhizobial trees were more abundant in dry than in wet ecosystems. By contrast, actinorhizal trees peaked in abundance at 5-10°C MAT and were least abundant in areas with intermediate precipitation. Next, we used a climate-envelope approach to project how N-fixing tree relative abundance might change in the future. The climate-envelope projection showed that rhizobial N-fixing trees will likely become more abundant in many areas by 2080, particularly in the southern USA and western Mexico, due primarily to rising temperatures. Projections for actinorhizal N-fixing trees were more nuanced due to their nonmonotonic dependence on temperature and precipitation. Overall, the dominant trend is that warming will increase N-fixing tree abundance in much of the USA and Mexico, with large increases up to 40° North latitude. The quantitative link we provide between climate and N-fixing tree abundance can help improve the representation of symbiotic N fixation in Earth System Models.

RevDate: 2018-09-04
CmpDate: 2018-09-04

Falgueras-Cano J, Carretero-Díaz JM, A Moya (2017)

Weighted fitness theory: an approach to symbiotic communities.

Environmental microbiology reports, 9(1):44-46.

RevDate: 2018-09-04
CmpDate: 2018-09-04

Diaz JM, Hansel CM, Apprill A, et al (2016)

Species-specific control of external superoxide levels by the coral holobiont during a natural bleaching event.

Nature communications, 7:13801 pii:ncomms13801.

The reactive oxygen species superoxide (O2·-) is both beneficial and detrimental to life. Within corals, superoxide may contribute to pathogen resistance but also bleaching, the loss of essential algal symbionts. Yet, the role of superoxide in coral health and physiology is not completely understood owing to a lack of direct in situ observations. By conducting field measurements of superoxide produced by corals during a bleaching event, we show substantial species-specific variation in external superoxide levels, which reflect the balance of production and degradation processes. Extracellular superoxide concentrations are independent of light, algal symbiont abundance and bleaching status, but depend on coral species and bacterial community composition. Furthermore, coral-derived superoxide concentrations ranged from levels below bulk seawater up to ∼120 nM, some of the highest superoxide concentrations observed in marine systems. Overall, these results unveil the ability of corals and/or their microbiomes to regulate superoxide in their immediate surroundings, which suggests species-specific roles of superoxide in coral health and physiology.

RevDate: 2018-09-04
CmpDate: 2018-09-04

Webster NS (2017)

Conceptual and methodological advances for holobiont research.

Environmental microbiology reports, 9(1):30-32.

RevDate: 2018-09-03

Hagymási K, Bacsárdi A, Egresi A, et al (2018)

[The role of gut microbiota in chronic liver diseases, and treatment possibilities].

Orvosi hetilap, 159(36):1465-1474.

The community of microorganisms in the intestine, namely gut microbiome lives in symbiosis with the host, contributing to its homeostasis and influencing it simultaneously. It can be suspected that gut microbiome plays a central role in the pathophysiology of intestinal and extraintestinal diseases: determining their development, progress and complications. Recently, intestinal microbiome has become a highlighted field of interest and important topic in research, especially in hepatology. It is in the focus of relevant research as the liver is the organ which meets nutrients, bacterial components, toxins and metabolites at first, as a filter. The evolvement of different liver diseases - just like alcoholic and non-alcoholic fatty liver disease, steatohepatitis, cirrhosis or hepatocellular carcinoma - correlates with the changed composition and activity of gut microbiome. Thus, it can be hypothesized that pre-, pro- and antibiotics could have an impact on the treatment of these diseases. In our review article, the relationship between intestinal flora and liver diseases with different etiologies as well as therapeutic possibilities are discussed. Orv Hetil. 2018; 159(36): 1465-1474.

RevDate: 2018-09-03
CmpDate: 2018-09-03

Pellizzaro A, Alibert B, Planchet E, et al (2017)

Nitrate transporters: an overview in legumes.

Planta, 246(4):585-595.

MAIN CONCLUSION: The nitrate transporters, belonging to NPF and NRT2 families, play critical roles in nitrate signaling, root growth and nodule development in legumes. Nitrate plays an essential role during plant development as nutrient and also as signal molecule, in both cases working via the activity of nitrate transporters. To date, few studies on NRT2 or NPF nitrate transporters in legumes have been reported, and most of those concern Lotus japonicus and Medicago truncatula. A molecular characterization led to the identification of 4 putative LjNRT2 and 37 putative LjNPF gene sequences in L. japonicus. In M. truncatula, the NRT2 family is composed of 3 putative members. Using the new genome annotation of M. truncatula (Mt4.0), we identified, for this review, 97 putative MtNPF sequences, including 32 new sequences relative to previous studies. Functional characterization has been published for only two MtNPF genes, encoding nitrate transporters of M. truncatula. Both transporters have a role in root system development via abscisic acid signaling: MtNPF6.8 acts as a nitrate sensor during the cell elongation of the primary root, while MtNPF1.7 contributes to the cellular organization of the root tip and nodule formation. An in silico expression study of MtNPF genes confirmed that NPF genes are expressed in nodules, as previously shown for L. japonicus, suggesting a role for the corresponding proteins in nitrate transport, or signal perception in nodules. This review summarizes our knowledge of legume nitrate transporters and discusses new roles for these proteins based on recent discoveries.

RevDate: 2018-09-03
CmpDate: 2018-09-03

Li Q, Ding G, Li B, et al (2017)

Transcriptome Analysis of Genes Involved in Dendrobine Biosynthesis in Dendrobium nobile Lindl. Infected with Mycorrhizal Fungus MF23 (Mycena sp.).

Scientific reports, 7(1):316 pii:10.1038/s41598-017-00445-9.

Content determination and microscopic observation proved that dendrobine accumulation in the stem of Dendrobium nobile Lindl. increased after infection with mycorrhizal fungus MF23 (Mycena sp.). Large-scale transcriptome sequencing of symbiotic and asymbiotic D. nobile revealed that 30 unigenes encoding proteins were possibly related to the biosynthesis of dendrobine sesquiterpene backbone. A qRT-PCR experiment of 16 unigenes, selected randomly, proved that there were significant changes in the expression levels of AACT, MVD, PMK and TPS21 at 9 weeks after inoculation. These results implied that MF23 might stimulate dendrobine biosynthesis by regulating the expressions of genes involved in the mevalonate (MVA) pathway. The biogenetic pathway of dendrobine was suggested systematically according to the structural features of dendrobine alkaloids and their sesquiterpene precursors, which implied that post-modification enzymes might play a major role in dendrobine biosynthesis. Thus, genes encoding post-modification enzymes, including cytochrome P450, aminotransferase and methyltransferase, were screened for their possible involvement in dendrobine biosynthesis. This study provides a good example of endophytes promoting the formation of bioactive compounds in their host and paves the way for further investigation of the dendrobine biosynthetic pathway.

RevDate: 2018-09-01

Tang J, Ni X, Zhou Z, et al (2018)

Acute microplastic exposure raises stress response and suppresses detoxification and immune capacities in the scleractinian coral Pocillopora damicornis.

Environmental pollution (Barking, Essex : 1987), 243(Pt A):66-74 pii:S0269-7491(18)32114-6 [Epub ahead of print].

Microplastics are widespread emerging contaminants that have been found globally in the marine and freshwater ecosystem, but there is limited knowledge regarding its impact on coral reef ecosystem and underpinning mechanism. In the present study, using Pocillopora damicornis as a model, we investigated cytological, physiological, and molecular responses of a scleractinian coral to acute microplastic exposure. No significant changes were observed in the density of symbiotic zooxanthellae during the entire period of microplastic exposure, while its chlorophyll content increased significantly at 12 h of microplastic exposure. We observed significant increases in the activities of antioxidant enzymes such as superoxide dismutase and catalase, significant decrease in the detoxifying enzyme glutathione S-transferase and the immune enzyme alkaline phosphatase, but no change in the other immune enzyme phenoloxidase during the whole experiment period. Transcriptomic analysis revealed 134 significantly up-regulated coral genes at 12 h after the exposure, enriched in 11 GO terms mostly related to stress response, zymogen granule, and JNK signal pathway. Meanwhile, 215 coral genes were significantly down-regulated at 12 h after exposure, enriched in 25 GO terms involved in sterol transport and EGF-ERK1/2 signal pathway. In contrast, only 12 zooxanthella genes exhibited significant up-regulation and 95 genes down-regulation at 12 h after the microplastic exposure; genes regulating synthesis and export of glucose and amino acids were not impacted. These results suggest that acute exposure of microplastics can activate the stress response of the scleractinian coral P. damicornis, and repress its detoxification and immune system through the JNK and ERK signal pathways. These demonstrate that microplastic exposure can compromise the anti-stress capacity and immune system of the scleractinian coral P. damicornis, despite the minimal impact on the abundance and major photosynthate translocation transporters of the symbiont in the short term.

RevDate: 2018-08-31

Yao S, Lyu S, An Y, et al (2018)

Microalgae-bacteria symbiosis in microalgal growth and biofuel production: a review.

Journal of applied microbiology [Epub ahead of print].

Photosynthetic microalgae can capture solar energy and convert it to bio-energy and bio-chemical products. In nature or industrial processes, microalgae live together with bacterial communities and may maintain symbiotic relationships. In general interactions, microalgae exude dissolved organic carbon that becomes available to bacteria. In return, the bacteria re-mineralize sulfur, nitrogen and phosphorous to support the further growth of microalgae. In specific interactions, heterotrophic bacteria supply B vitamins as organic cofactors or produce siderophores to bind iron, which could be utilized by microalgae, while the algae supply fixed carbon to the bacteria in return. In this review, we focus on mutualistic relationship between microalgae and bacteria, summarizing recent studies on the mechanisms involved in microalgae-bacteria symbiosis. Symbiotic bacteria on promoting microalgal growth are described and the relevance of microalgae-bacteria interactions for biofuel production processes is discussed. Symbiotic microalgae-bacteria consortia could be utilized to improve microalgal biomass production and to enrich the biomass with valuable chemical and energy compounds. The suitable control of such biological interactions between microalgae and bacteria will help to improve the microalgae-based biomass and biofuel production in the future. This article is protected by copyright. All rights reserved.

RevDate: 2018-08-31

Tsikou D, Yan Z, Holt DB, et al (2018)

Systemic control of legume susceptibility to rhizobial infection by a mobile microRNA.

Science (New York, N.Y.) pii:science.aat6907 [Epub ahead of print].

Nitrogen-fixing root nodules on legumes result from two developmental processes, bacterial infection and nodule organogenesis. To balance symbiosis and plant growth, legume hosts restrict nodule numbers through an inducible autoregulatory process. Here, we present a mechanism where repression of a negative regulator ensures symbiotic susceptibility of uninfected roots of the host Lotus japonicus We show that microRNA miR2111 undergoes shoot-to-root translocation to control rhizobial infection through posttranscriptional regulation of the symbiosis suppressor TOO MUCH LOVE in roots. miR2111 maintains a susceptible default status in uninfected hosts and functions as an activator of symbiosis downstream of LOTUS HISTIDINE KINASE1-mediated cytokinin perception in roots and HYPERNODULATION ABERRANT ROOT FORMATION1, a shoot factor in autoregulation. The miR2111-TML node ensures activation of feedback regulation to balance infection and nodulation events.

RevDate: 2018-08-31

Aguilar A, Mora Y, Dávalos A, et al (2018)

Analysis of genome sequence and symbiotic ability of rhizobial strains isolated from seeds of common bean (Phaseolus vulgaris).

BMC genomics, 19(1):645 pii:10.1186/s12864-018-5023-0.

BACKGROUND: Rhizobia are alpha-proteobacteria commonly found in soil and root nodules of legumes. It was recently reported that nitrogen-fixing rhizobia also inhabit legume seeds. In this study, we examined whole-genome sequences of seven strains of rhizobia isolated from seeds of common bean (Phaseolus vulgaris).

RESULTS: Rhizobial strains included in this study belonged to three different species, including Rhizobium phaseoli, R. leguminosarum, and R. grahamii. Genome sequence analyses revealed that six of the strains formed three pairs of highly related strains. Both strains comprising a pair shared all but one plasmid. In two out of three pairs, one of the member strains was effective in nodulation and nitrogen fixation, whereas the other was ineffective. The genome of the ineffective strain in each pair lacked several genes responsible for symbiosis, including nod, nif, and fix genes, whereas that of the effective strain harbored the corresponding genes in clusters, suggesting that recombination events provoked gene loss in ineffective strains. Comparisons of genomic sequences between seed strains and nodule strains of the same species showed high conservation of chromosomal sequences and lower conservation of plasmid sequences. Approximately 70% of all genes were shared among the strains of each species. However, paralogs were more abundant in seed strains than in nodule strains. Functional analysis showed that seed strains were particularly enriched in genes involved in the transport and metabolism of amino acids and carbohydrates, biosynthesis of cofactors and in transposons and prophages. Genomes of seed strains harbored several intact prophages, one of which was inserted at exactly the same genomic position in three strains of R. phaseoli and R. leguminosarum. The R. grahamii strain carried a prophage similar to a gene transfer agent (GTA); this represents the first GTA reported for this genus.

CONCLUSIONS: Seeds represent a niche for bacteria; their access by rhizobia possibly triggered the infection of phages, recombination, loss or gain of plasmids, and loss of symbiosis genes. This process probably represents ongoing evolution that will eventually convert these strains into obligate endophytes.

RevDate: 2018-08-30
CmpDate: 2018-08-30

Kageyama D, Yoshimura K, Sugimoto TN, et al (2017)

Maternally transmitted non-bacterial male killer in Drosophila biauraria.

Biology letters, 13(10):.

A maternally inherited, all-female trait is widely found among arthropods, which is caused by bacterial endosymbionts such as Wolbachia, Rickettsia, Spiroplasma and Cardinium We discovered a single female of Drosophila biauraria, collected from Tomakomai, Hokkaido, Japan, that produced all-female offspring. This all-female trait was maternally inherited in the iso-female line (SP12F) by backcrossing with males of a normal line (SP11-20) with a 1 : 1 sex ratio derived from the same population. The all-female trait was not affected by tetracycline treatment performed for two consecutive generations. However, the microinjection of filter-sterilized homogenate of SP12F females into SP11-20 females established all-female matrilines. Our data suggest the role of transmissible agents, most likely viruses, but not bacteria or protists, as the possible cause of the all-female phenotype, which is likely to be achieved by killing of male embryos because egg hatch rates of SP12F were nearly half those of SP11-20. This is the first report in Diptera to demonstrate a maternally inherited virus-like element as the cause of the male-killing phenotype in D. biauraria.

RevDate: 2018-08-30
CmpDate: 2018-08-30

Pawlik M, Cania B, Thijs S, et al (2017)

Hydrocarbon degradation potential and plant growth-promoting activity of culturable endophytic bacteria of Lotus corniculatus and Oenothera biennis from a long-term polluted site.

Environmental science and pollution research international, 24(24):19640-19652.

Many endophytic bacteria exert beneficial effects on their host, but still little is known about the bacteria associated with plants growing in areas heavily polluted by hydrocarbons. The aim of the study was characterization of culturable hydrocarbon-degrading endophytic bacteria associated with Lotus corniculatus L. and Oenothera biennis L. collected in long-term petroleum hydrocarbon-polluted site using culture-dependent and molecular approaches. A total of 26 hydrocarbon-degrading endophytes from these plants were isolated. Phylogenetic analyses classified the isolates into the phyla Proteobacteria and Actinobacteria. The majority of strains belonged to the genera Rhizobium, Pseudomonas, Stenotrophomonas, and Rhodococcus. More than 90% of the isolates could grow on medium with diesel oil, approximately 20% could use n-hexadecane as a sole carbon and energy source. PCR analysis revealed that 40% of the isolates possessed the P450 gene encoding for cytochrome P450-type alkane hydroxylase (CYP153). In in vitro tests, all endophytic strains demonstrated a wide range of plant growth-promoting traits such as production of indole-3-acetic acid, hydrogen cyanide, siderophores, and phosphate solubilization. More than 40% of the bacteria carried the gene encoding for the 1-aminocyclopropane-1-carboxylic acid deaminase (acdS). Our study shows that the diversity of endophytic bacterial communities in tested plants was different. The results revealed also that the investigated plants were colonized by endophytic bacteria possessing plant growth-promoting features and a clear potential to degrade hydrocarbons. The properties of isolated endophytes indicate that they have the high potential to improve phytoremediation of petroleum hydrocarbon-polluted soils.

RevDate: 2018-08-30
CmpDate: 2018-08-30

Vu DL, L Kaiser (2017)

The concept of commensal viruses almost 20 years later: redefining borders in clinical virology.

Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases, 23(10):688-690.

RevDate: 2018-08-29

Allen JL, McKenzie SK, Sleith RS, et al (2018)

First genome-wide analysis of the endangered, endemic lichen Cetradonia linearis reveals isolation by distance and strong population structure.

American journal of botany [Epub ahead of print].

PREMISE OF THE STUDY: Lichenized fungi are evolutionarily diverse and ecologically important, but little is known about the processes that drive their diversification and genetic differentiation. Distributions are often assumed to be wholly shaped by ecological requirements rather than dispersal limitations. Furthermore, although asexual and sexual reproductive structures are observable, the lack of information about recombination rates makes inferences about reproductive strategies difficult. We investigated the population genomics of Cetradonia linearis, a federally endangered lichen in the southern Appalachians of eastern North America, to test the relative contributions of environmental and geographic distance in shaping genetic structure, and to characterize the mating system and genome-wide recombination.

METHODS: Whole-genome shotgun sequencing was conducted to generate data for 32 individuals of C. linearis. A reference genome was assembled, and reads from all samples were aligned to generate a set of single-nucleotide polymorphisms for further analyses.

KEY RESULTS: We found evidence for low rates of recombination and for isolation by distance, but not for isolation by environment. The species is putatively unisexual, given that only one mating-type locus was found. Hindcast species distribution models and the distribution of genetic diversity support C. linearis having a larger range during the Last Glacial Maximum in the southern portion of its current extent.

CONCLUSIONS: Our findings contribute to the understanding of factors that shape genetic diversity in C. linearis and in fungi more broadly. Because all populations are highly genetically differentiated, the extirpation of any population would mean the loss of unique genetic diversity; therefore, our results support the continued conservation of this species.

RevDate: 2018-08-29

Cafiso A, Sassera D, Romeo C, et al (2018)

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

Ticks and tick-borne diseases pii:S1877-959X(18)30247-4 [Epub ahead of print].

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

RevDate: 2018-08-29
CmpDate: 2018-08-29

Logan SL, Thomas J, Yan J, et al (2018)

The Vibrio cholerae type VI secretion system can modulate host intestinal mechanics to displace gut bacterial symbionts.

Proceedings of the National Academy of Sciences of the United States of America, 115(16):E3779-E3787.

Host-associated microbiota help defend against bacterial pathogens; however, the mechanisms by which pathogens overcome this defense remain largely unknown. We developed a zebrafish model and used live imaging to directly study how the human pathogen Vibrio cholerae invades the intestine. The gut microbiota of fish monocolonized by symbiotic strain Aeromonas veronii was displaced by V. cholerae expressing its type VI secretion system (T6SS), a syringe-like apparatus that deploys effector proteins into target cells. Surprisingly, displacement was independent of T6SS-mediated killing of A. veronii, driven instead by T6SS-induced enhancement of zebrafish intestinal movements that led to expulsion of the resident microbiota by the host. Deleting an actin cross-linking domain from the T6SS apparatus returned intestinal motility to normal and thwarted expulsion, without weakening V. cholerae's ability to kill A. veronii in vitro. Our finding that bacteria can manipulate host physiology to influence intermicrobial competition has implications for both pathogenesis and microbiome engineering.

RevDate: 2018-08-28

Wang M, Schäfer M, Li D, et al (2018)

Blumenols as shoot markers for root symbiosis with arbuscular mycorrhizal fungi.

eLife, 7: pii:37093 [Epub ahead of print].

High-through-put (HTP) screening for functional arbuscular mycorrhizal fungi (AMF)-associations is challenging because roots must be excavated and colonization evaluated by transcript analysis or microscopy. Here we show that specific leaf-metabolites provide broadly applicable accurate proxies of these associations, suitable for HTP-screens. With a combination of untargeted and targeted metabolomics, we show that shoot accumulations of hydroxy- and carboxyblumenol C-glucosides mirror root AMF-colonization in Nicotiana attenuata plants. Genetic/pharmacologic manipulations indicate that these AMF-indicative foliar blumenols are synthesized and transported from roots to shoots. These blumenol-derived foliar markers, found in many di- and monocotyledonous crop and model plants (Solanum lycopersicum, Solanum tuberosum, Hordeum vulgare, Triticum aestivum, Medicago truncatula and Brachypodium distachyon), are not restricted to particular plant-AMF interactions, and are shown to be applicable for field-based QTL mapping of AMF-related genes.

RevDate: 2018-08-28

Russo G, Carotenuto G, Fiorilli V, et al (2018)

Ectopic activation of cortical cell division during the accommodation of arbuscular mycorrhizal fungi.

The New phytologist [Epub ahead of print].

Arbuscular mycorrhizas (AMs) between plants and soil fungi are widespread symbioses with a major role in soil nutrient uptake. In this study we investigated the induction of root cortical cell division during AM colonization by combining morphometric and gene expression analyses with promoter activation and protein localization studies of the cell-plate-associated exocytic marker TPLATE. Our results show that TPLATE promoter is activated in colonized cells of the root cortex where we also observed the appearance of cells that are half the size of the surrounding cells. Furthermore, TPLATE-green fluorescent protein recruitment to developing cell plates highlighted ectopic cell division events in the inner root cortex during early AM colonization. Lastly, transcripts of TPLATE, KNOLLE and Cyclinlike 1 (CYC1) are all upregulated in the same context, alongside endocytic markers Adaptor-Related Protein complex 2 alpha 1 subunit (AP2A1) and Clathrin Heavy Chain 2 (CHC2), known to be active during cell plate formation. This pattern of gene expression was recorded in wild-type Medicago truncatula roots, but not in a common symbiotic signalling pathway mutant where fungal colonization is blocked at the epidermal level. Altogether, these results suggest the activation of cell-division-related mechanisms by AM hosts during the accommodation of the symbiotic fungus.

RevDate: 2018-08-28

Mason CJ, Jones AG, GW Felton (2018)

Co-option of microbial associates by insects and their impact on plant-folivore interactions.

Plant, cell & environment [Epub ahead of print].

Plants possess a suite of traits that make them challenging to consume by insect herbivores. Plant tissues are recalcitrant, have low levels of protein, and may be well defended by chemicals. Insects use diverse strategies for overcoming these barriers, including co-opting metabolic activities from microbial associates. In this review, we discuss the co-option of bacteria and fungi in the herbivore gut. We particularly focus upon chewing, folivorous insects (Coleoptera and Lepidoptera), and discuss the impacts of microbial co-option on herbivore performance and plant responses. We suggest that there are two components to microbial co-option; fixed and plastic relationships. Fixed relationships are involved in integral dietary functions, and can be performed by microbial enzymes co-opted into the genome or by stably transferred associates. In contrast, the majority of gut symbionts appear to be looser, and perform more facultative, context-dependent functions. This more plastic, variable co-option of bacteria likely produces a greater number of insect phenotypes, which interact differently with plant hosts. By altering plant detection of herbivory or mediating insect interactions with plant defensive compounds, microbes can effectively improve herbivore performance in real-time within and between generations.

RevDate: 2018-08-28

Coryell RL, Turnham KE, de Jesus Ayson EG, et al (2018)

Phylogeographic patterns in the Philippine archipelago influence symbiont diversity in the bobtail squid-Vibrio mutualism.

Ecology and evolution, 8(15):7421-7435 pii:ECE34266.

Marine microbes encounter a myriad of biotic and abiotic factors that can impact fitness by limiting their range and capacity to move between habitats. This is especially true for environmentally transmitted bacteria that cycle between their hosts and the surrounding habitat. As geologic history, biogeography, and other factors such as water temperature, salinity, and physical barriers can inhibit bacterial movement to novel environments, we chose to examine the genetic architecture of Euprymna albatrossae (Mollusca: Cephalopoda) and their Vibrio fischeri symbionts in the Philippine archipelago using a combined phylogeographic approach. Eleven separate sites in the Philippine islands were examined using haplotype estimates that were examined via nested clade analysis to determine the relationship between E. albatrossae and V. fischeri populations and their geographic location. Identical analyses of molecular variance (AMOVA) were used to estimate variation within and between populations for host and symbiont genetic data. Host animals demonstrated a significant amount of variation within island groups, while symbiont variation was found within individual populations. Nested clade phylogenetic analysis revealed that hosts and symbionts may have colonized this area at different times, with a sudden change in habitat. Additionally, host data indicate restricted gene flow, whereas symbionts show range expansion, followed by periodic restriction to genetic flow. These differences between host and symbiont networks indicate that factors "outside the squid" influence distribution of Philippine V. fischeri. Our results shed light on how geography and changing environmental factors can impact marine symbiotic associations at both local and global scales.


ESP Quick Facts

ESP Origins

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

ESP Support

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

ESP Rationale

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

ESP Goal

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

ESP Usage

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

ESP Content

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

ESP Help

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

ESP Plans

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

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

E-mail: RJR8222 @

Papers in Classical Genetics

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

Digital Books

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


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


Biographical information about many key scientists.

Selected Bibliographies

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

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