Project description:Copper (Cu) plays an essential role in cellular metabolism and limits phytoplankton growth and production in parts of the open sea. Whole transcriptome analysis provides a powerful tool to explore gene expression profiles and cellular metabolic pathways regulated by Cu. In this study, we identified Cu-regulated genes by profiling the transcriptomes of an oceanic diatom, Thalassiosira oceanica 1005, adapted to survive in a Cu-limited and Cu-replete environment. The results provide insights to the mechanisms of adaptation and acclimation of T. oceanica to low Cu environments.
Project description:Enhanced vertical stratification brought about by warming of the ocean surface is expected to reduce vertical circulation and nutrient input with knock-on effects for phytoplankton. Increased nutrient limitation is one predicted outcome, but the response of phytoplankton is uncertain because long-term adaptation to nutrient limitation has not been studied. We used Cu as a model catalytic nutrient to explore the adaptive response of an oceanic diatom to continuous nutrient deprivation. Thalassiosira oceanica was maintained under Cu-limiting and sufficient conditions for more than 2000 generations and the evolved populations evaluated for physiological traits in a reciprocal transplant experiment. Adaptation to low Cu concentration increased Cu use efficiency, so that under Cu-limiting conditions T. oceanica maintained significantly faster rates of net C assimilation and growth than the control and ancestral populations.
Project description:The oceanic diatom Pseudo-nitzschia granii was cultured in the laboratory under steady-state iron-replete and iron-limited conditions. Transcriptomic and proteomic analyses were performed to determine how this organism reorganizes major metabolic processes as a function of iron supply.
Project description:In many regions of the ocean, anthropogenic warming will coincide with iron (Fe) limitation. Interactive effects between warming and Fe limitation on phytoplankton physiology and biochemical function are likely, as temperature and Fe availability affect many of the same essential cellular pathways. However, we lack a clear understanding of how globally significant phytoplankton such as the picocyanobacteria Synechococcus will respond to these co-occurring stressors, and what underlying molecular mechanisms will drive this response. Additionally, there are likely to be important differences in ecotype-specific adaptations between strains. In this study, Synechococcus isolates YX04-1 (oceanic) and XM-24 (coastal) from the South China Sea were acclimated to Fe limitation at two temperatures, and their physiological and proteomic responses were compared.
