Dataset Information

Characterization of Gut Microbiome in the Mussel Mytilus galloprovincialis in Response to Thermal Stress.

ABSTRACT: The gut microbiota is essential for utilization of energy and nutrition and may have a role in host immunity in response to environmental shifts. The present study evaluated the temperature stress (increasing from 21 to 27°C) on gut microbiome and dynamics of the mussel Mytilus galloprovincialis by 16S rRNA gene sequencing with the aim of discovering the gut microbiome resilience to warming. Exposure to high temperature of 27°C significantly reduced the survival of M. galloprovincialis associated with increased microbial diversity of gut. The microbial communities were shifted with elevated temperature (from 21 to 27°C) and different exposure time (from day 0 to day 7) by principal coordinate analysis (PCoA). Linear discriminant analysis effect size (LEfSe) revealed that the relative abundance of Vibrio and Arcobacter presented in live animals as the top genus-level biomarkers during the initial exposure to 27°C and followed by microbiomes fluctuation with increasing exposure time at day 4 and day 7. The proliferation of opportunistic pathogens such as genus Vibrio and Arcobacter might increase host susceptibility to disease and contributed greatly to mortality. The results obtained in this study provide the knowledge on ecological adaptation for south domestication of M. galloprovincialis and host-bacteria interaction during temperature stress (27°C).

SUBMITTER: Li YF

PROVIDER: S-EPMC6714297 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Characterization of Gut Microbiome in the Mussel Mytilus galloprovincialis in Response to Thermal Stress.

Li Yi-Feng YF Xu Jia-Kang JK Chen Yan-Wen YW Ding Wen-Yang WY Shao An-Qi AQ Liang Xiao X Zhu You-Ting YT Yang Jin-Long JL

Frontiers in physiology 20190822

The gut microbiota is essential for utilization of energy and nutrition and may have a role in host immunity in response to environmental shifts. The present study evaluated the temperature stress (increasing from 21 to 27°C) on gut microbiome and dynamics of the mussel Mytilus galloprovincialis by 16S rRNA gene sequencing with the aim of discovering the gut microbiome resilience to warming. Exposure to high temperature of 27°C significantly reduced the survival of M. galloprovincialis ...[more]

PMID: 31507449

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Project description:Adaptive responses to thermal stress in poikilotherms plays an important role in determining competitive ability and species distributions. Amino acid substitutions that affect protein stability and modify the thermal optima of orthologous proteins may be particularly important in this context. Here, we examine a set of 2,770 protein-coding genes to determine if proteins in a highly invasive heat tolerant blue mussel (Mytilus galloprovincialis) contain signals of adaptive increases in protein stability relative to orthologs in a more cold tolerant M. trossulus. Such thermal adaptations might help to explain, mechanistically, the success with which the invasive marine mussel M. galloprovincialis has displaced native species in contact zones in the eastern (California) and western (Japan) Pacific. We tested for stabilizing amino acid substitutions in warm tolerant M. galloprovincialis relative to cold tolerant M. trossulus with a generalized linear model that compares in silico estimates of recent changes in protein stability among closely related congeners. Fixed substitutions in M. galloprovincialis were 3,180.0 calories per mol per substitution more stabilizing at genes with both elevated dN/dS ratios and transcriptional responses to heat stress, and 705.8 calories per mol per substitution more stabilizing across all 2,770 loci investigated. Amino acid substitutions concentrated in a small number of genes were more stabilizing in M. galloprovincialis compared with cold tolerant M. trossulus. We also tested for, but did not find, enrichment of a priori GO terms in genes with elevated dN/dS ratios in M. galloprovincialis. This might indicate that selection for thermodynamic stability is generic across all lineages, and suggests that the high change in estimated protein stability that we observed in M. galloprovincialis is driven by selection for extra stabilizing substitutions, rather than by higher incidence of selection in a greater number of genes in this lineage. Nonetheless, our finding of more stabilizing amino acid changes in the warm adapted lineage is important because it suggests that adaption for thermal stability has contributed to M. galloprovincialis' superior tolerance to heat stress, and that pairing tests for positive selection and tests for transcriptional response to heat stress can identify candidates of protein stability adaptation.

Project description:BACKGROUND: Sessile bivalves of the genus Mytilus are suspension feeders relatively tolerant to a wide range of environmental changes, used as sentinels in ecotoxicological investigations and marketed worldwide as seafood. Mortality events caused by infective agents and parasites apparently occur less in mussels than in other bivalves but the molecular basis of such evidence is unknown. The arrangement of Mytibase, interactive catalogue of 7,112 transcripts of M. galloprovincialis, offered us the opportunity to look for gene sequences relevant to the host defences, in particular the innate immunity related genes. RESULTS: We have explored and described the Mytibase sequence clusters and singletons having a putative role in recognition, intracellular signalling, and neutralization of potential pathogens in M. galloprovincialis. Automatically assisted searches of protein signatures and manually cured sequence analysis confirmed the molecular diversity of recognition/effector molecules such as the antimicrobial peptides and many carbohydrate binding proteins. Molecular motifs identifying complement C1q, C-type lectins and fibrinogen-like transcripts emerged as the most abundant in the Mytibase collection whereas, conversely, sequence motifs denoting the regulatory cytokine MIF and cytokine-related transcripts represent singular and unexpected findings. Using a cross-search strategy, 1,820 putatively immune-related sequences were selected to design oligonucleotide probes and define a species-specific Immunochip (DNA microarray). The Immunochip performance was tested with hemolymph RNAs from mussels injected with Vibrio splendidus at 3 and 48 hours post-treatment. A total of 143 and 262 differentially expressed genes exemplify the early and late hemocyte response of the Vibrio-challenged mussels, respectively, with AMP trends confirmed by qPCR and clear modulation of interrelated signalling pathways. CONCLUSIONS: The Mytibase collection is rich in gene transcripts modulated in response to antigenic stimuli and represents an interesting window for looking at the mussel immunome (transcriptomes mediating the mussel response to non-self or abnormal antigens). On this basis, we have defined a new microarray platform, a mussel Immunochip, as a flexible tool for the experimental validation of immune-candidate sequences, and tested its performance on Vibrio-activated mussel hemocytes. The microarray platform and related expression data can be regarded as a step forward in the study of the adaptive response of the Mytilus species to an evolving microbial world.

Project description:Transcriptional profiling of mussel (Mytilus galloprovincialis) digestive gland tissue comparing control tissue with tissue obtained from animals exposed for four days to sublethal amounts of Nickel, Chlorpyrifos, or their mixture. Background: Mixtures of chemicals present in aquatic environments may elicit toxicity due to additive or synergistic effects among the constituents or ‘vice versa’ the adverse outcome may be reduced by antagonistic interactions. Deviations from additivity should be explained either by the perturbations of toxicokinetic parameters and/or chemical toxicodynamics. We addressed this important question in marine mussels exposed subchronically to a binary mixture made of two wide-spread pollutants: the heavy metal Nickel and the organic phosphorus pesticide Chlorpyrifos. To this aim, we proposed the use of a systems approach based on the evaluation and integration of different disciplines, i.e. high throughput gene expression profiling, functional genomics, stress biomakers and toxicokinetics. Results: Stress biomarkers showed statistically significant antagonistic deviations from the reference model systems to predict mixture toxicity which are based either on simple additivity or non-interaction. While toxicokinetic modeling did not explain mixture interactions, gene expression profiling and further functional genomics analysis provided clues that the decrement of toxicity may arise from the development of specific toxicodynamics. Multivariate statistics of microarray and quantitative PCR data showed two separate patterns for the single chemicals and a composite complex profile for the mixture suggesting the occurrence of interactive molecular responses. The latter signature accounted for differentially expressed genes whose relative expression values were either in trend or in contrast with those found due to single substance treatments and a relevant set of sequences which were exclusive of the mixture gene list. Conclusion: The functional genomics assessment fits with biological data to indicate the occurrence of different toxicodynamic events and ‘in general’ a decrease of toxicity, driven by the mitigation or even abolishment of lysosomal responses such as the lipid metabolic disorder observed exclusively in single chemical-exposed samples. Furthermore, our results emphasized the importance of the application of mechanistic approaches and the power of systems assessment to study toxicological responses in ecological relevant organisms.

Project description:Endogenously determined inter-individual differences in growth rate of bivalve molluscs have been widely analyzed at different organizational levels. Most studies have focused on the characterization of the physiological differences between fast (F) and slow (S) growing individuals. Although several genes have been described to be up regulated on fast growing individuals, the molecular basis underlying the mechanisms at the origin of growth variation is still poorly understood. In the present study we reared mussel spat of the species Mytilus galloprovincialis under diets below the pseudofaeces threshold (BP) and above the pseudofaeces threshold (AP). After 3 months, F and S mussels on each condition were selected, so that 4 experimental groups were obtained: FBP, SBP, FAP and SAP. We hypothesized that nurturing conditions during their growing period would modify the molecular basis of growth rate differences. However, results of feeding experiments showed that F mussels displayed higher clearance and ingestion rates and higher efficiencies of food selection prior to ingestion, as well as higher gill surface areas, irrespective of the rearing nutritional environment. To decipher molecular mechanism at the origin of growth variation, gills of the 4 mussel groups were dissected, and used for transcriptome analysis with a custom Agilent single channel microarray. Gene expression analysis revealed i) a low number (12) of genes differentially expressed associated to maintenance condition differences and ii) 117 genes differentially expressed when comparing fast and slow growing mussels (FBP + FAP vs. SBP + SAP). We further investigated this comparison: GO terms and KEGG pathway association of the differentially expressed genes allowed us to analyze the functions involved on the differentially expressed encoding. Transcriptomic differences between F and S mussels were mainly based on the up-regulation of response to stimulus, growth and cell activity Biological Process GO terms. Regarding the KEGG terms, carbohydrate metabolism and Krebs cycle were found to be up-regulated in F mussels whereas biosynthetic processes were up-regulated in S mussels. Among the differentially expressed genes that are annotated, the following ones were found to be up regulated in F mussels: i) Mucin, related to mucus secretion, known to be crucial in food acquisition and pre-ingestive selection processes in bivalves, ii) genes related to growth such as Myostatin or Insulin-like growth factor, iii) genes involved in feeding activity, such as Fibrocystin or Dynein and iv) genes involved in the energetic metabolism; Citrate synthase. S mussels mainly over-expressed genes related to immune system and defence (Leucine-rich repeat-containing protein, Metalloendopeptidase, Small heat shock protein 24, Multidrug resistance,…).The present results suggest that differences in feeding activity and in the allocation of metabolic energy between growth groups could account for the differences in growth rate in spat of Mytilus galloprovincialis. In accordance with their higher feeding rates and growth, fast growing mussels were found to mainly over-express genes involved in the development and maintenance of such activities, however, slow growing mussels needed to expend energy in immune and defence processes to ensure survival at the expense of growth rate.

Dataset Information

Characterization of Gut Microbiome in the Mussel Mytilus galloprovincialis in Response to Thermal Stress.

Publications

Characterization of Gut Microbiome in the Mussel <i>Mytilus galloprovincialis</i> in Response to Thermal Stress.

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