ABSTRACT: Metabolic activity and community structure of prokaryotes associated with Particulate Organic Carbon in the Twilight Zone of the South China Sea
Project description:In the present study, we studied microbial composition and metabolic activity in the bathypelagic zone of the South China Sea. 12 samples were collected and subjected to metaproteomic analysis. Our data provide a novel view of the roles of two lifestyle prokaryotes and their link in substrate utilization in dark ocean.
Project description:In the present study, we studied microbial composition and metabolic activity in the euphotic zone of the South China Sea. 8 samples were collected and subjected to metaproteomic analysis. Our results suggested that mixotrophic phototrophs-driven NDL carbon fixation along with phytoplankton-driven NRL carbon fixation determined primary production in the oligotrophic ocean’s euphotic zone.
Project description:Particulate Organic Matter from filter samples (0.2um Supor, 3um Supor, 52 Nitex) in the oxygen deficient zone of the Eastern tropical Northern Pacific.
Project description:This study was designed to identify differentially expressed (DE) genes between natural breastfeeding young South China tiger whole blood and artificial feeding young South China tiger whole blood through microarray and bioinformatics analysis, thus trying to identify modified metabolic pathways as a consequence of milk replacer during the suckling period.
Project description:we characterized the microbial communities and proteomes of POC collected from the twilight zone at three contrasting sites in the northwest Pacific Ocean using a metaproteomic approach.Particle-attached bacteria, Alteromonadales, Rhodobacterales and Enterobacteriales, were the major remineralizers of POC in the twilight zone.
Project description:Anthropogenic nitrogen (N) deposition may affect soil organic carbon (SOC) decomposition, thus affecting the global terrestrial carbon (C) cycle. However, it remains unclear how the level of N deposition affects SOC decomposition by regulating microbial community composition and function, especially C-cycling functional genes structure. We investigated the effects of short-term N addition on soil microbial C-cycling functional gene composition, SOC-degrading enzyme activities, and CO2 emission in a 5-year field experiment established in an artificial Pinus tabulaeformis forest on the Loess Plateau, China.
Project description:To investigate the cellular responses induced by air pollution exposures, we performed genome-wide gene expression microarray analysis using whole blood RNA sampled at three time-points across the work weeks of 63 non-smoking employees in the trucking industry. Our objective was to identify the genes and gene networks differentially activated in response to micro-environmental measures of occupational exposure to three pollutants: PM2.5 (particulate matter ≤ 2.5 microns in diameter) and elemental carbon (EC) and organic carbon (OC).
Project description:<p>Metabolites, or the small organic molecules that are synthesized by cells during metabolism, comprise a complex and dynamic pool of carbon in the ocean. They are an essential form of information, linking genotype to phenotype at the individual, population and community levels of biological organization. Characterizing metabolite distributions inside microbial cells and dissolved in seawater is essential to understanding the controls on their production and fate, as well as their roles in shaping marine microbial food webs. Here, we apply a targeted metabolomics method to quantify particulate and dissolved distributions of a suite of biologically relevant metabolites including vitamins, amino acids, nucleic acids, osmolytes, and intermediates in biosynthetic pathways along a latitudinal transect in the western Atlantic Ocean. We find that, in the euphotic zone, most particulate or intracellular metabolites positively co-vary with the most abundant microbial taxa. In contrast, dissolved metabolites exhibited greater variability with differences in distribution between ocean regions. Although fewer particulate metabolites were detected below the euphotic zone, molecules identified in the deep ocean may be linked to preservation of organic matter or adaptive physiological strategies of deep-sea microbes. Based on the identified metabolite distributions, we propose relationships between certain metabolites and microbial populations, and find that dissolved metabolite distributions are not directly related to their particulate abundances.</p>
Project description:<p>Particulate organic matter (fecal pellets) from zooplankton has been demonstrated to be important nutrient sources for the pelagic prokaryotic community. Significantly less is known about the chemical composition of the dissolved organic matter (DOM) produced by these eukaryotes and its influence on pelagic ecosystem structure. Zooplankton migrators, which daily transport surface-derived compounds to depth, may act as important vectors of limiting nutrients for mesopelagic microbial communities. In this role, zooplankton may increase the DOM remineralization rate by heterotrophic prokaryotes through the creation of nutrient rich “hot spots” that could potentially increase niche diversity. To explore these interactions, we collected the migratory copepod Pleuromamma xiphias from the northwestern Sargasso Sea and sampled its excreta after 12-16 h of incubation. We measured bulk dissolved organic carbon, dissolved free amino acids via high performance liquid chromatography and dissolved targeted metabolites via quantitative mass spectrometry (UPLC-ESI-MSMS) to quantify organic zooplankton excreta production and characterize its composition. We observed production of labile DOM, including amino acids, vitamins and nucleosides. Additionally, we harvested a portion of the excreta and subsequently used it as the growth medium for mesopelagic (200m) bacterioplankton dilution cultures. In zooplankton excreta treatments we observed a four-fold increase in bacterioplankton cell densities that reached stationary growth phase after five days of dark incubation. Analyses of 16s rDNA amplicons suggested a shift from oligotrophs typical of open ocean and mesopelagic prokaryotic communities to more copiotrophic bacterial lineages in the presence of zooplankton excreta. These results support the hypothesis that zooplankton and prokaryotes are engaged in complex and indirect ecological interactions, broadening our understanding of the microbial loop.</p>
