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1.
Proc Biol Sci ; 287(1922): 20200049, 2020 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-32126963

RESUMO

The density of dinoflagellate microalgae in the tissue of symbiotic corals is an important determinant for health and productivity of the coral animal. Yet, the specific mechanism for their regulation and the consequence for coral nutrition are insufficiently understood due to past methodological limitations to resolve the fine-scale metabolic consequences of fluctuating densities. Here, we characterized the physiological and nutritional consequences of symbiont density variations on the colony and tissue level in Stylophora pistillata from the Red Sea. Alterations in symbiont photophysiology maintained coral productivity and host nutrition across a broad range of symbiont densities. However, we demonstrate that density-dependent nutrient competition between individual symbiont cells, manifested as reduced nitrogen assimilation and cell biomass, probably creates the negative feedback mechanism for symbiont population growth that ultimately defines the steady-state density. Despite fundamental changes in symbiont nitrogen assimilation, we found no density-related metabolic optimum beyond which host nutrient assimilation or tissue biomass declined, indicating that host nutrient demand is sufficiently met across the typically observed range of symbiont densities under ambient conditions.


Assuntos
Antozoários/fisiologia , Dinoflagelados/fisiologia , Simbiose/fisiologia , Animais , Recifes de Corais , Nitrogênio/metabolismo
3.
PLoS One ; 15(2): e0228880, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32040535

RESUMO

Despite its high ecological importance, the commensal interactions at community level are poorly studied. In tropical dry forests (TDF) there is a great diversity of species adapted to the high seasonality that characterizes them; however, little is known regarding how the spatial and temporal availability of resources generates changes in the pattern of commensal interactions. We experimentally studied changes in the diversity, composition, and pattern of interactions in spatio-temporal associations between the saproxylophagous beetles and their host trees in a TDF in Morelos, Mexico. A total of 65 host tree species were selected, from which 16 wood sections were obtained per species. These sections were exposed in the field to allow oviposition by the cerambycids under four different (spatio-temporal) treatments. We analyzed the network structure and generated indices at species level (i.e., specialization, species strength, and effective partners) and those related to physical characteristics of the wood (hardness and degradation rate) and the cerambycids (body size). In total, 1,323 individuals of 57 species of cerambycids emerged. Our results showed that, independently of the space and time, the network presented a nested and modular structure, with a high specialization degree and a high turnover of cerambycid species and their interactions. In general, we found that the cerambycids are mostly associated with softwood species with a lower decomposition rate of wood, as well as with the most abundant host species. The commensalistic interactions between the cerambycids and their host trees are highly specialized but are not spatio-temporally static. The high turnover in the interactions is caused by the emergence patterns of cerambycids, which seem to restrict their use to certain species. The knowledge of the spatio-temporal variation in Cerambycidae-host tree interactions allows us to predict how environmental and structural changes in the habitat can modify the species ensemble, and therefore its interactions.


Assuntos
Besouros/fisiologia , Interações Hospedeiro-Parasita/fisiologia , Árvores/parasitologia , Animais , Biodiversidade , Besouros/patogenicidade , Ecossistema , Feminino , Florestas , Especificidade de Hospedeiro , México , Oviposição , Análise Espaço-Temporal , Simbiose/fisiologia , Clima Tropical , Madeira
4.
Proc Natl Acad Sci U S A ; 117(3): 1806-1815, 2020 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-31900357

RESUMO

Leguminous plants establish endosymbiotic associations with rhizobia and form root nodules in which the rhizobia fix atmospheric nitrogen. The host plant and intracellular rhizobia strictly control this symbiotic nitrogen fixation. We recently reported a Lotus japonicus Fix- mutant, apn1 (aspartic peptidase nodule-induced 1), that impairs symbiotic nitrogen fixation. APN1 encodes a nodule-specific aspartic peptidase involved in the Fix- phenotype in a rhizobial strain-specific manner. This host-strain specificity implies that some molecular interactions between host plant APN1 and rhizobial factors are required, although the biological function of APN1 in nodules and the mechanisms governing the interactions are unknown. To clarify how rhizobial factors are involved in strain-specific nitrogen fixation, we explored transposon mutants of Mesorhizobium loti strain TONO, which normally form Fix- nodules on apn1 roots, and identified TONO mutants that formed Fix+ nodules on apn1 The identified causal gene encodes an autotransporter, part of a protein secretion system of Gram-negative bacteria. Expression of the autotransporter gene in M. loti strain MAFF3030399, which normally forms Fix+ nodules on apn1 roots, resulted in Fix- nodules. The autotransporter of TONO functions to secrete a part of its own protein (a passenger domain) into extracellular spaces, and the recombinant APN1 protein cleaved the passenger protein in vitro. The M. loti autotransporter showed the activity to induce the genes involved in nodule senescence in a dose-dependent manner. Therefore, we conclude that the nodule-specific aspartic peptidase, APN1, suppresses negative effects of the rhizobial autotransporter in order to maintain effective symbiotic nitrogen fixation in root nodules.


Assuntos
Lotus/metabolismo , Fixação de Nitrogênio/fisiologia , Rhizobium/metabolismo , Simbiose/fisiologia , Sistemas de Secreção Tipo V/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Regulação da Expressão Gênica de Plantas , Genes Bacterianos/genética , Bactérias Gram-Negativas , Mesorhizobium/genética , Mesorhizobium/metabolismo , Modelos Moleculares , Fixação de Nitrogênio/genética , Fenótipo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Conformação Proteica , Domínios Proteicos , Rhizobium/genética , Nódulos Radiculares de Plantas/crescimento & desenvolvimento , Nódulos Radiculares de Plantas/metabolismo , Simbiose/genética , Transcriptoma , Sistemas de Secreção Tipo V/química , Sistemas de Secreção Tipo V/genética
5.
Arch Microbiol ; 202(2): 369-375, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31673721

RESUMO

Methanol, a by-product associated with plant metabolism, is a substrate for pink pigmented facultative methylotrophs (PPFMs) of phyllosphere. The symbiotic interaction of PPFMs has many desirable effects on plant growth and disease resistance. The present study investigated the potential of native PPFMs for mitigating biotic stress and plant growth promotion in ginger. PPFMs were isolated from ginger phyllosphere by leaf imprint technique and screened against major fungal phytopathogens of ginger viz. Macrophomina phaseolina, Sclerotium rolfsii, Pythium myriotylum, Colletotrichum gloeosporioides and Fusarium oxysporum. Among the 60 PPFMs, IISRGPPFM13 was selected for its highly inhibitory activity against the target pathogens. The isolate was useful for mineral solubility, production of IAA, siderophores and hydrolytic enzymes like cellulase, pectinase, lipase, amylase and chitinase. On in planta experiments revealed that IISRGPPFM13 considerably increased plant growth parameters when the bacterium was applied as soil drenching cum foliar spraying. Methanol utilization potential of the isolate was confirmed by mxaF gene analysis where the sequence showing 95.51% identity towards Methylobacterium platani and M. iners. Further, 16S rRNA gene sequence showing 98.73% identity with M. komagatae 002-079 T (AB252201). This is the first report of its kind that a genus of Methylobacterium with biostimulant potential isolated from the phyllosphere of ginger.


Assuntos
Gengibre/crescimento & desenvolvimento , Gengibre/microbiologia , Metanol/metabolismo , Methylobacterium/metabolismo , Celulase/metabolismo , Methylobacterium/genética , Folhas de Planta/microbiologia , Plantas/metabolismo , RNA Ribossômico 16S/genética , Solo , Microbiologia do Solo , Simbiose/fisiologia
6.
ISME J ; 14(2): 649-656, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31680119

RESUMO

Deep-sea Bathymodiolus mussels and their chemoautotrophic symbionts are well-studied representatives of mutualistic host-microbe associations. However, how host-symbiont interactions vary on the molecular level between related host and symbiont species remains unclear. Therefore, we compared the host and symbiont metaproteomes of Pacific B. thermophilus, hosting a thiotrophic symbiont, and Atlantic B. azoricus, containing two symbionts, a thiotroph and a methanotroph. We identified common strategies of metabolic support between hosts and symbionts, such as the oxidation of sulfide by the host, which provides a thiosulfate reservoir for the thiotrophic symbionts, and a cycling mechanism that could supply the host with symbiont-derived amino acids. However, expression levels of these processes differed substantially between both symbioses. Backed up by genomic comparisons, our results furthermore revealed an exceptionally large repertoire of attachment-related proteins in the B. thermophilus symbiont. These findings imply that host-microbe interactions can be quite variable, even between closely related systems.


Assuntos
Bactérias/genética , Bactérias/metabolismo , Mytilidae/microbiologia , Simbiose/genética , Aminoácidos/genética , Aminoácidos/metabolismo , Animais , Anidrases Carbônicas/metabolismo , Crescimento Quimioautotrófico , Genoma Bacteriano/genética , Brânquias/metabolismo , Interações entre Hospedeiro e Microrganismos , Mytilidae/metabolismo , Proteômica , Simbiose/fisiologia
7.
Arch Microbiol ; 202(2): 391-398, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31680188

RESUMO

Bacterial surface molecules have an important role in the rhizobia-legume symbiosis. Ensifer meliloti (previously, Sinorhizobium meliloti), a symbiotic Gram-negative rhizobacterium, produces two different exopolysaccharides (EPSs), termed EPS I (succinoglycan) and EPS II (galactoglucan), with different functions in the symbiotic process. Accordingly, we undertook a study comparing the potential differences in alfalfa nodulation by E. meliloti strains with differences in their EPSs production. Strains recommended for inoculation as well as laboratory strains and native strains isolated from alfalfa fields were investigated. This study concentrated on EPS-II production, which results in mucoid colonies that are dependent on the presence of an intact expR gene. The results revealed that although the studied strains exhibited different phenotypes, the differences did not affect alfalfa nodulation itself. However, subtle changes in timing and efficacy to the effects of inoculation with the different strains may result because of other as-yet unknown factors. Thus, additional research is needed to determine the most effective inoculant strains and the best conditions for improving alfalfa production under agricultural conditions.


Assuntos
Galactanos/metabolismo , Glucanos/metabolismo , Medicago sativa/metabolismo , Medicago sativa/microbiologia , Polissacarídeos Bacterianos/metabolismo , Sinorhizobium meliloti/metabolismo , Proteínas de Bactérias/genética , Fertilizantes/microbiologia , Regulação Bacteriana da Expressão Gênica , Nodulação/fisiologia , Simbiose/fisiologia
8.
Arch Microbiol ; 202(1): 1-16, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31552478

RESUMO

The acerbic elevation of toxic metal ions in arable lands, enhance the risk of their accumulation and biomagnification in crops as well as in humans. Phytoremediation is an eco-friendly approach to clear metal-contaminated lands by making use of metal accumulation potential of plants; which are referred to as hyperaccumulators. This phytoremediation potential can be enhanced with the symbiotic association between the root of hyperaccumulators and arbuscular mycorrhizae. Modification of root morphology, enhancement of antioxidants biosynthesis, and the increase in shoot biomass are the changes observed in plants as a result of indirect influence of arbuscular mycorrhizae. Direct influence of arbuscular mycorrhizae on enhancing metal tolerance of plants includes immobilization strategies, adsorption of metals on to the hyphal wall and glomalin exudation. Furthermore, we have discussed arbuscular mycorrhizal induced increment in the metal tolerance potential of plants through the alteration in various metabolic processes with special emphasis to the phenylpropanoid pathway.


Assuntos
Biodegradação Ambiental , Metais/toxicidade , Micorrizas/metabolismo , Raízes de Plantas/microbiologia , Plantas/efeitos dos fármacos , Plantas/microbiologia , Simbiose/fisiologia , Biomassa , Poluentes do Solo/toxicidade
9.
Nat Commun ; 10(1): 5606, 2019 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-31811209

RESUMO

Feeding on unicellular photosynthetic organisms by unicellular eukaryotes is the base of the aquatic food chain and evolutionarily led to the establishment of photosynthetic endosymbionts/organelles. Photosynthesis generates reactive oxygen species and damages cells; thus, photosynthetic organisms possess several mechanisms to cope with the stress. Here, we demonstrate that photosynthetic prey also exposes unicellular amoebozoan and excavates predators to photosynthetic oxidative stress. Upon illumination, there is a commonality in transcriptomic changes among evolutionarily distant organisms feeding on photosynthetic prey. One of the genes commonly upregulated is a horizontally transferred homolog of algal and plant genes for chlorophyll degradation/detoxification. In addition, the predators reduce their phagocytic uptake while accelerating digestion of photosynthetic prey upon illumination, reducing the number of photosynthetic cells inside the predator cells, as this also occurs in facultative endosymbiotic associations upon certain stresses. Thus, some mechanisms in predators observed here probably have been necessary for evolution of endosymbiotic associations.


Assuntos
Cadeia Alimentar , Fotossíntese/fisiologia , Comportamento Predatório/fisiologia , Simbiose/fisiologia , Amebozoários/fisiologia , Amebozoários/efeitos da radiação , Animais , Bactérias/metabolismo , Fenômenos Fisiológicos Bacterianos , Evolução Biológica , Clorofila , Técnicas de Cocultura , Eucariotos , Evolução Molecular , Luz/efeitos adversos , Naegleria/crescimento & desenvolvimento , Naegleria/fisiologia , Organelas/fisiologia , Estresse Oxidativo , Fagocitose/fisiologia , Comportamento Predatório/efeitos da radiação , Domínios Proteicos , Espécies Reativas de Oxigênio , Simbiose/efeitos da radiação , Transcriptoma
10.
PLoS Biol ; 17(11): e3000533, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31710600

RESUMO

The significance of symbioses between eukaryotic hosts and microbes extends from the organismal to the ecosystem level and underpins the health of Earth's most threatened marine ecosystems. Despite rapid growth in research on host-associated microbes, from individual microbial symbionts to host-associated consortia of significantly relevant taxa, little is known about their interactions with the vast majority of marine host species. We outline research priorities to strengthen our current knowledge of host-microbiome interactions and how they shape marine ecosystems. We argue that such advances in research will help predict responses of species, communities, and ecosystems to stressors driven by human activity and inform future management strategies.


Assuntos
Organismos Aquáticos/microbiologia , Microbiota/fisiologia , Simbiose/fisiologia , Animais , Bactérias/classificação , Ecossistema , Interações entre Hospedeiro e Microrganismos/fisiologia , Humanos
11.
Nat Commun ; 10(1): 5047, 2019 11 06.
Artigo em Inglês | MEDLINE | ID: mdl-31695035

RESUMO

Plants associate with beneficial arbuscular mycorrhizal fungi facilitating nutrient acquisition. Arbuscular mycorrhizal fungi produce chitooligosaccharides (COs) and lipo-chitooligosaccharides (LCOs), that promote symbiosis signalling with resultant oscillations in nuclear-associated calcium. The activation of symbiosis signalling must be balanced with activation of immunity signalling, which in fungal interactions is promoted by COs resulting from the chitinaceous fungal cell wall. Here we demonstrate that COs ranging from CO4-CO8 can induce symbiosis signalling in Medicago truncatula. CO perception is a function of the receptor-like kinases MtCERK1 and LYR4, that activate both immunity and symbiosis signalling. A combination of LCOs and COs act synergistically to enhance symbiosis signalling and suppress immunity signalling and receptors involved in both CO and LCO perception are necessary for mycorrhizal establishment. We conclude that LCOs, when present in a mix with COs, drive a symbiotic outcome and this mix of signals is essential for arbuscular mycorrhizal establishment.


Assuntos
Quitina/análogos & derivados , Lipopolissacarídeos/metabolismo , Medicago truncatula/microbiologia , Micorrizas/fisiologia , Morte Celular , Parede Celular/metabolismo , Quitina/metabolismo , Quitina/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Lipopolissacarídeos/farmacologia , Medicago truncatula/efeitos dos fármacos , Medicago truncatula/genética , Medicago truncatula/imunologia , Oligossacarídeos/metabolismo , Imunidade Vegetal , Folhas de Planta , Proteínas de Plantas/genética , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Proteínas Serina-Treonina Quinases/metabolismo , Transdução de Sinais/efeitos dos fármacos , Simbiose/efeitos dos fármacos , Simbiose/fisiologia , Tabaco
12.
BMC Biol ; 17(1): 91, 2019 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-31739792

RESUMO

BACKGROUND: Symbiotic relationships between microbes and their hosts are widespread and diverse, often providing protection or nutrients, and may be either obligate or facultative. However, the genetic mechanisms allowing organisms to maintain host-symbiont associations at the molecular level are still mostly unknown, and in the case of bacterial-animal associations, most genetic studies have focused on adaptations and mechanisms of the bacterial partner. The gutless tubeworms (Siboglinidae, Annelida) are obligate hosts of chemoautotrophic endosymbionts (except for Osedax which houses heterotrophic Oceanospirillales), which rely on the sulfide-oxidizing symbionts for nutrition and growth. Whereas several siboglinid endosymbiont genomes have been characterized, genomes of hosts and their adaptations to this symbiosis remain unexplored. RESULTS: Here, we present and characterize adaptations of the cold seep-dwelling tubeworm Lamellibrachia luymesi, one of the longest-lived solitary invertebrates. We sequenced the worm's ~ 688-Mb haploid genome with an overall completeness of ~ 95% and discovered that L. luymesi lacks many genes essential in amino acid biosynthesis, obligating them to products provided by symbionts. Interestingly, the host is known to carry hydrogen sulfide to thiotrophic endosymbionts using hemoglobin. We also found an expansion of hemoglobin B1 genes, many of which possess a free cysteine residue which is hypothesized to function in sulfide binding. Contrary to previous analyses, the sulfide binding mediated by zinc ions is not conserved across tubeworms. Thus, the sulfide-binding mechanisms in sibgolinids need to be further explored, and B1 globins might play a more important role than previously thought. Our comparative analyses also suggest the Toll-like receptor pathway may be essential for tolerance/sensitivity to symbionts and pathogens. Several genes related to the worm's unique life history which are known to play important roles in apoptosis, cell proliferation, and aging were also identified. Last, molecular clock analyses based on phylogenomic data suggest modern siboglinid diversity originated in 267 mya (± 70 my) support previous hypotheses indicating a Late Mesozoic or Cenozoic origins of approximately 50-126 mya for vestimentiferans. CONCLUSIONS: Here, we elucidate several specific adaptations along various molecular pathways that link phenome to genome to improve understanding of holobiont evolution. Our findings of adaptation in genomic mechanisms to reducing environments likely extend to other chemosynthetic symbiotic systems.


Assuntos
Crescimento Quimioautotrófico , Genoma/fisiologia , Poliquetos/genética , Poliquetos/microbiologia , Simbiose/fisiologia , Animais , Fontes Hidrotermais
13.
Proc Natl Acad Sci U S A ; 116(49): 24712-24718, 2019 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-31740601

RESUMO

The thermal tolerance of an organism limits its ecological and geographic ranges and is potentially affected by dependence on temperature-sensitive symbiotic partners. Aphid species vary widely in heat sensitivity, but almost all aphids are dependent on the nutrient-provisioning intracellular bacterium Buchnera, which has evolved with aphids for 100 million years and which has a reduced genome potentially limiting heat tolerance. We addressed whether heat sensitivity of Buchnera underlies variation in thermal tolerance among 5 aphid species. We measured how heat exposure of juvenile aphids affects later survival, maturation time, and fecundity. At one extreme, heat exposure of Aphis gossypii enhanced fecundity and had no effect on the Buchnera titer. In contrast, heat suppressed Buchnera populations in Aphis fabae, which suffered elevated mortality, delayed development and reduced fecundity. Likewise, in Acyrthosiphon kondoi and Acyrthosiphon pisum, heat caused rapid declines in Buchnera numbers, as well as reduced survivorship, development rate, and fecundity. Fecundity following heat exposure is severely decreased by a Buchnera mutation that suppresses the transcriptional response of a gene encoding a small heat shock protein. Similarly, absence of this Buchnera heat shock gene may explain the heat sensitivity of Ap. fabae Fluorescent in situ hybridization revealed heat-induced deformation and shrinkage of bacteriocytes in heat-sensitive species but not in heat-tolerant species. Sensitive and tolerant species also differed in numbers and transcriptional responses of heat shock genes. These results show that shifts in Buchnera heat sensitivity contribute to host variation in heat tolerance.


Assuntos
Afídeos/fisiologia , Buchnera/fisiologia , Simbiose/fisiologia , Termotolerância/fisiologia , Animais , Afídeos/microbiologia , Buchnera/isolamento & purificação , Feminino , Especificidade de Hospedeiro/fisiologia , Temperatura Alta/efeitos adversos
14.
Protist ; 170(6): 125698, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31760169

RESUMO

Strigomonas culicis is a kinetoplastid parasite of insects that maintains a mutualistic association with an intracellular symbiotic bacterium, which is highly integrated into the protist metabolism: it furnishes essential compounds and divides in synchrony with the eukaryotic nucleus. The protist, conversely, can be cured of the endosymbiont, producing an aposymbiotic cell line, which presents a diminished ability to colonize the insect host. This obligatory association can represent an intermediate step of the evolution towards the formation of an organelle, therefore representing an interesting model to understand the symbiogenesis theory. Here, we used shotgun proteomics to compare the S. culicis endosymbiont-containing and aposymbiotic strains, revealing a total of 11,305 peptides, and up to 2,213 proteins (2,029 and 1,452 for wild type and aposymbiotic, respectively). Gene ontology associated to comparative analysis between both strains revealed that the biological processes most affected by the elimination of the symbiont were the amino acid synthesis, as well as protein synthesis and folding. This large-scale comparison of the protein expression in S. culicis marks a step forward in the comprehension of the role of endosymbiotic bacteria in monoxenous trypanosomatid biology, particularly because trypanosomatids expression is mostly post-transcriptionally regulated.


Assuntos
Fenômenos Fisiológicos Bacterianos , Proteoma/genética , Simbiose/fisiologia , Trypanosomatina/microbiologia , Trypanosomatina/genética
15.
FEMS Microbiol Lett ; 366(23)2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31750894

RESUMO

Symbiosis between intracellular bacteria (endosymbionts) and animals are widespread. The alphaproteobacterium Wolbachia pipientis is known to maintain a variety of symbiotic associations, ranging from mutualism to parasitism, with a wide range of invertebrates. Wolbachia infection might deeply affect host fitness (e.g. reproductive manipulation and antiviral protection), which is thought to explain its high prevalence in nature. Bacterial loads significantly influence both the infection dynamics and the extent of bacteria-induced host phenotypes. Hence, fine regulation of bacterial titers is considered as a milestone in host-endosymbiont interplay. Here, we review both environmental and biological factors modulating Wolbachia titers in arthropods.


Assuntos
Artrópodes/microbiologia , Simbiose/fisiologia , Wolbachia/fisiologia , Animais , Carga Bacteriana , Meio Ambiente
16.
PLoS Comput Biol ; 15(10): e1007323, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31581264

RESUMO

Mutualisms may be "key innovations" that spur lineage diversification by augmenting niche breadth, geographic range, or population size, thereby increasing speciation rates or decreasing extinction rates. Whether mutualism accelerates diversification in both interacting lineages is an open question. Research suggests that plants that attract ant mutualists have higher diversification rates than non-ant associated lineages. We ask whether the reciprocal is true: does the interaction between ants and plants also accelerate diversification in ants, i.e. do ants and plants cooperate-and-radiate? We used a novel text-mining approach to determine which ant species associate with plants in defensive or seed dispersal mutualisms. We investigated patterns of lineage diversification across a recent ant phylogeny using BiSSE, BAMM, and HiSSE models. Ants that associate mutualistically with plants had elevated diversification rates compared to non-mutualistic ants in the BiSSE model, with a similar trend in BAMM, suggesting ants and plants cooperate-and-radiate. However, the best-fitting model was a HiSSE model with a hidden state, meaning that diversification models that do not account for unmeasured traits are inappropriate to assess the relationship between mutualism and ant diversification. Against a backdrop of diversification rate heterogeneity, the best-fitting HiSSE model found that mutualism actually decreases diversification: mutualism evolved much more frequently in rapidly diversifying ant lineages, but then subsequently slowed diversification. Thus, it appears that ant lineages first radiated, then cooperated with plants.


Assuntos
Mineração de Dados/métodos , Simbiose/fisiologia , Animais , Formigas/genética , Evolução Biológica , Ecossistema , Variação Genética/fisiologia , Fenótipo , Filogenia , Plantas/metabolismo
17.
PLoS Biol ; 17(10): e3000268, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31622337

RESUMO

Imaging dense and diverse microbial communities has broad applications in basic microbiology and medicine, but remains a grand challenge due to the fact that many species adopt similar morphologies. While prior studies have relied on techniques involving spectral labeling, we have developed an expansion microscopy method (µExM) in which bacterial cells are physically expanded prior to imaging. We find that expansion patterns depend on the structural and mechanical properties of the cell wall, which vary across species and conditions. We use this phenomenon as a quantitative and sensitive phenotypic imaging contrast orthogonal to spectral separation to resolve bacterial cells of different species or in distinct physiological states. Focusing on host-microbe interactions that are difficult to quantify through fluorescence alone, we demonstrate the ability of µExM to distinguish species through an in vitro defined community of human gut commensals and in vivo imaging of a model gut microbiota, and to sensitively detect cell-envelope damage caused by antibiotics or previously unrecognized cell-to-cell phenotypic heterogeneity among pathogenic bacteria as they infect macrophages.


Assuntos
Acetobacter/ultraestrutura , Escherichia coli/ultraestrutura , Lactobacillus plantarum/ultraestrutura , Microscopia/métodos , Muramidase/farmacologia , Acetobacter/efeitos dos fármacos , Acidaminococcus/efeitos dos fármacos , Acidaminococcus/ultraestrutura , Animais , Antibacterianos/farmacologia , Parede Celular/química , Parede Celular/efeitos dos fármacos , Parede Celular/ultraestrutura , Drosophila melanogaster/microbiologia , Escherichia coli/efeitos dos fármacos , Microbioma Gastrointestinal/fisiologia , Humanos , Hidrólise , Lactobacillus plantarum/efeitos dos fármacos , Camundongos , Microscopia/instrumentação , Muramidase/química , Platelmintos/microbiologia , Células RAW 264.7 , Estresse Mecânico , Simbiose/fisiologia , Vancomicina/farmacologia
18.
Commun Biol ; 2: 368, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31633059

RESUMO

Microbes can enter into healthy plants as endophytes and confer beneficial functions. The entry of commensal microbes into plants involves penetrating plant defense. Most mechanisms about overcoming plant defense are focused on adapted pathogens, while the mechanism involved in beneficial endophyte evades plant defense to achieve harmonious commensalism is unclear. Here, we discover a mechanism that an endophyte bacterium Bacillus subtilis BSn5 reduce to stimulate the plant defensive response by producing lantibiotic subtilomycin to bind self-produced flagellin. Subtilomycin bind with flagellin and affect flg22-induced plant defense, by which means promotes the endophytic colonization in A. thaliana. Subtilomycin also promotes the BSn5 colonization in a distinct plant, Amorphophallus konjac, where the BSn5 was isolated. Our investigation shows more independent subtilomycin/-like producers are isolated from distinct plants. Our work unveils a common strategy that is used for bacterial endophytic colonization.


Assuntos
Bacillus subtilis/metabolismo , Bacteriocinas/metabolismo , Endófitos/metabolismo , Flagelina/metabolismo , Imunidade Vegetal , Amorphophallus/metabolismo , Amorphophallus/microbiologia , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Imunidade Vegetal/fisiologia , Simbiose/fisiologia
19.
PLoS One ; 14(10): e0212655, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31596856

RESUMO

Photorhabdus luminescens is an entomopathogenic bacterium found in symbiosis with the nematode Heterorhabditis. Dam DNA methylation is involved in the pathogenicity of many bacteria, including P. luminescens, whereas studies about the role of bacterial DNA methylation during symbiosis are scarce. The aim of this study was to determine the role of Dam DNA methylation in P. luminescens during the whole bacterial life cycle including during symbiosis with H. bacteriophora. We constructed a strain overexpressing dam by inserting an additional copy of the dam gene under the control of a constitutive promoter in the chromosome of P. luminescens and then achieved association between this recombinant strain and nematodes. The dam overexpressing strain was able to feed the nematode in vitro and in vivo similarly as a control strain, and to re-associate with Infective Juvenile (IJ) stages in the insect. No difference in the amount of emerging IJs from the cadaver was observed between the two strains. Compared to the nematode in symbiosis with the control strain, a significant increase in LT50 was observed during insect infestation with the nematode associated with the dam overexpressing strain. These results suggest that during the life cycle of P. luminescens, Dam is not involved the bacterial symbiosis with the nematode H. bacteriophora, but it contributes to the pathogenicity of the nemato-bacterial complex.


Assuntos
Proteínas de Bactérias/metabolismo , Insetos/microbiologia , Nematoides/microbiologia , Photorhabdus/enzimologia , DNA Metiltransferases Sítio Específica (Adenina-Específica)/metabolismo , Simbiose/fisiologia , Animais
20.
Proc Natl Acad Sci U S A ; 116(43): 21758-21768, 2019 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-31591240

RESUMO

Several Bradyrhizobium species nodulate the leguminous plant Aeschynomene indica in a type III secretion system-dependent manner, independently of Nod factors. To date, the underlying molecular determinants involved in this symbiotic process remain unknown. To identify the rhizobial effectors involved in nodulation, we mutated 23 out of the 27 effector genes predicted in Bradyrhizobium strain ORS3257. The mutation of nopAO increased nodulation and nitrogenase activity, whereas mutation of 5 other effector genes led to various symbiotic defects. The nopM1 and nopP1 mutants induced a reduced number of nodules, some of which displayed large necrotic zones. The nopT and nopAB mutants induced uninfected nodules, and a mutant in a yet-undescribed effector gene lost the capacity for nodule formation. This effector gene, widely conserved among bradyrhizobia, was named ernA for "effector required for nodulation-A." Remarkably, expressing ernA in a strain unable to nodulate A. indica conferred nodulation ability. Upon its delivery by Pseudomonas fluorescens into plant cells, ErnA was specifically targeted to the nucleus, and a fluorescence resonance energy transfer-fluorescence lifetime imaging microscopy approach supports the possibility that ErnA binds nucleic acids in the plant nuclei. Ectopic expression of ernA in A. indica roots activated organogenesis of root- and nodule-like structures. Collectively, this study unravels the symbiotic functions of rhizobial type III effectors playing distinct and complementary roles in suppression of host immune functions, infection, and nodule organogenesis, and suggests that ErnA triggers organ development in plants by a mechanism that remains to be elucidated.


Assuntos
Bradyrhizobium/metabolismo , Fabaceae/microbiologia , Organogênese Vegetal/fisiologia , Nodulação/fisiologia , Nódulos Radiculares de Plantas/metabolismo , Bradyrhizobium/genética , Nitrogenase/genética , Nitrogenase/metabolismo , Organogênese Vegetal/genética , Raízes de Plantas/metabolismo , Pseudomonas fluorescens/genética , Simbiose/fisiologia , Sistemas de Secreção Tipo III/metabolismo
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