Project description:<p>Organic carbon in seawater plays a significant role in the global carbon cycle. The concentration and composition of dissolved organic carbon, operationally defined in this project as organic carbon that passes through a 0.2 µm filter, reflect the actions of the biological community and chemical reactions that occur in seawater. Here, we repeatedly sampled the oligotrophic northwest Sargasso Sea in the vicinity of the Bermuda Atlantic Time-Series Study site (BATS) to quantitatively follow select known compounds within the pool of dissolved organic matter in the upper 1000 meters of the water column over a four-year period. Metabolite concentrations revealed patterns with depth and time with most metabolites showing surface enrichment and lower concentrations with depth. Select metabolites had a pattern of increased and decreased concentrations throughout the year, which was observed in each of the years sampled. Vitamins, including pantothenic acid, biotin, and riboflavin, presented annual increases in the winter period when mixed layer depths are deepest. Light-sensitive riboflavin also showed significant decreases during daylight hours under diel sampling. The metabolites examined in this study are all components of central carbon metabolism. By examining these metabolites at finer resolution and in a relatively long time series, we have clues on microbial actions in marine systems, data which are fundamental to understanding the chemical response of marine systems to future changes in climate.</p>
Project description:Anthropogenic nutrient inputs alter soil biodiversity; however, it remains largely unknown whether changes in soil microeukaryotes (fungi and protists) are primarily driven by direct effects, such as modifications in soil properties, or by indirect effects, such as plant diversity loss. To disentangle these mechanisms, we investigated the long-term effects (11 years) of fertilization and manipulated plant diversity (1, 2, or 4 plant species) on soil microeukaryote communities in a temperate grassland experiment using long-amplicon rRNA sequencing. Our results indicate that fertilization generally had a stronger influence on microeukaryote communities than plant species richness. Fertilization altered the community composition of fungi and protists, increased OTU richness by 20.8% and 52.7%, respectively, and shifted community dominance from fungi to protists. Regarding plant diversity, we observed an effect exclusively on the protist community. Changes were primarily explained by increased plant biomass (driven by both fertilization and plant diversity) and by higher soil phosphorus and lower soil pH levels (driven exclusively by fertilization). Regarding life strategies, we observed synergistic treatment effects: fertilization primarily enhanced fungal saprophytes (only richness), fungal animal pathogens, and protist consumers, whereas plant diversity affected phototrophic protists (reduction) and protist animal pathogens (enhancement). Notably, fertilization and plant diversity decline together led to a cumulative increase in fungal plant pathogens. In conclusion, we highlight that fertilisation alone has a significant effect on soil microeukaryotes, while the additional decline in plant diversity affects different soil groups that are not directly affected by fertilisation. This synergistic pattern indicates that fertilization can influence the entire microeukaryote community through direct and indirect mechanisms, with a cumulative enhancement on certain groups, such as plant pathogens.
Project description:To investigate the mechanism of annual rhythms in Japanese cedar, annual time series samples were collected from the cuttings planted in natural condition. Also, to investigate the effects of photoperiod and temperature during transition to dormancy, the samples of cuttings grown in the controlled-environmental chamber were analyzed by a microarray.
Project description:Rising atmospheric CO2 concentrations are leading to ocean acidification, altering the inorganic carbon buffer system with consequences for marine organisms. Here we applied RNA-seq and iTRAQ quantification to investigate the potential impacts of ocean acidification on the temperate coastal marine diatom Skeletonema marinoi.