Project description:Eutrophication can lead to an uncontrollable increase in algal biomass, which has repercussions for the entire microbial and pelagic community. Studies have shown how nutrient enrichment affects microbial species succession, however details regarding the impact on community functionality are rare. Here, we applied a metaproteomic approach to investigate the functional changes to algal and bacterial communities, over time, in oligotrophic and eutrophic conditions, in freshwater microcosms. Samples were taken early during algal and cyanobacterial dominance and later under bacterial dominance. 1048 proteins, from the two treatments and two timepoints, were identified and quantified by their exponentially modified protein abundance index. In oligotrophic conditions, Bacteroidetes express extracellular hydrolases and Ton-B dependent receptors to degrade and transport high molecular weight compounds captured while attached to the phycosphere. Alpha- and Beta-proteobacteria were found to capture different substrates from algal exudate (carbohydrates and amino acids, respectively) suggesting resource partitioning to avoid direct competition. In eutrophic conditions, environmental adaptation proteins from cyanobacteria suggested better resilience compared to algae in a low carbon nutrient enriched environment. This study provides insight into differences in functional microbial processes between oligo- and eutrophic conditions at different timepoints and highlights how primary producers control bacterial resources in freshwater environments.
Project description:Xiangjiang River (Hunan, China) has been contaminated with heavy metal for several decades by surrounding factories. However, little is known about the influence of a gradient of heavy metal contamination on the diversity, structure of microbial functional gene in sediment. To deeply understand the impact of heavy metal contamination on microbial community, a comprehensive functional gene array (GeoChip 5.0) has been used to study the functional genes structure, composition, diversity and metabolic potential of microbial community from three heavy metal polluted sites of Xiangjiang River. Three groups of samples, A, B and C. Every group has 3 replicates.
Project description:Three-spined stickleback (Gasterosteus aculeatus) represents a convenient model to study microevolution - adaptation to freshwater environment. While genetic adaptations to freshwater are well-studied, epigenetic adaptations attracted little attention. In this work, we investigated the role of DNA methylation in the adaptation of marine stickleback population to freshwater conditions. DNA methylation profiling was performed in marine and freshwater populations of sticklebacks, as well as in marine sticklebacks placed into freshwater environment and freshwater sticklebacks placed into seawater. For the first time, we demonstrated that genes encoding ion channels kcnd3, cacna1fb, gja3 are differentially methylated between marine and freshwater populations. We also showed that after placing marine stickleback into fresh water, its DNA methylation profile partially converges to the one of a freshwater stickleback. This suggests that immediate epigenetic response to freshwater conditions can be maintained in freshwater population. Interestingly, we observed enhanced epigenetic plasticity in freshwater sticklebacks that may serve as a compensatory regulatory mechanism for the lack of genetic variation in the freshwater population. Some of the regions that were reported previously to be under selection in freshwater populations also show differential methylation. Thus, epigenetic changes might represent a parallel mechanism of adaptation along with genetic selection in freshwater environment. This is the RNA-seq experiment, DNA methylation data (bisulfite-seq) is provided under accession number GSE82310.
Project description:Xiangjiang River (Hunan, China) has been contaminated with heavy metal for several decades by surrounding factories. However, little is known about the influence of a gradient of heavy metal contamination on the diversity, structure of microbial functional gene in sediment. To deeply understand the impact of heavy metal contamination on microbial community, a comprehensive functional gene array (GeoChip 5.0) has been used to study the functional genes structure, composition, diversity and metabolic potential of microbial community from three heavy metal polluted sites of Xiangjiang River.
Project description:Three-spined stickleback (Gasterosteus aculeatus) represents a convenient model to study microevolution - adaptation to freshwater environment. While genetic adaptations to freshwater are well-studied, epigenetic adaptations attracted little attention. In this work, we investigated the role of DNA methylation in the adaptation of marine stickleback population to freshwater conditions. DNA methylation profiling was performed in marine and freshwater populations of sticklebacks, as well as in marine sticklebacks placed into freshwater environment and freshwater sticklebacks placed into seawater. For the first time, we demonstrated that genes encoding ion channels kcnd3, cacna1fb, gja3 are differentially methylated between marine and freshwater populations. We also showed that after placing marine stickleback into fresh water, its DNA methylation profile partially converges to the one of a freshwater stickleback. This suggests that immediate epigenetic response to freshwater conditions can be maintained in freshwater population. Interestingly, we observed enhanced epigenetic plasticity in freshwater sticklebacks that may serve as a compensatory regulatory mechanism for the lack of genetic variation in the freshwater population. Some of the regions that were reported previously to be under selection in freshwater populations also show differential methylation. Thus, epigenetic changes might represent a parallel mechanism of adaptation along with genetic selection in freshwater environment.