En-Gen: Genome-Enabled Environmental Functional Genomics and Expression Profiling of Diatoms in the Ocean

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Diatoms contribute up to 25 % of total ocean productivity and are the basis of the world's greatest fisheries. Their genomes appear to be finely tuned to succeed under the environmental conditions of the modern world. They grow rapidly into blooms and draw down the ambient carbon dioxide to very low levels, and respond rapidly to essential nutrients such as nitrate and iron when they become available. Even in non-bloom conditions, they can grow as rapidly as the small and abundant cyanobacteria. Unlike the cyanobacteria, however, insights into their success from functional and comparative genomics have not been possible until now. This project will use newly available diatom genomes to discover which genes are highly expressed by natural assemblages in the environment in order to learn directly from the organisms about the nature and time frame of their response to different environmental conditions. The approach in this project builds on previous results from these investigators using single gene studies and data from libraries of gene sequences derived from cultures under conditions of iron and nitrogen stress. The investigators have identified a suite of candidate genes to study that are involved in carbon and nitrogen metabolism, and the stress response to nutrient limitation. These genes will be deployed on a diagnostic microarray to discover which genes are highly expressed in natural seawater under bloom and nutrient limiting conditions. These approaches will allow the investigators to identify critical gene targets for functional genomics research in diatoms in order to investigate the response of marine diatoms to environmental factors, including changes resulting from elevated temperatures and decreasing pH as a result of increasing atmospheric carbon dioxide, and to predict physiological and possibly community responses to nutrient stress. Diatoms are relative newcomers to the modern world, having evolved under dramatically different environmental conditions than those present at the beginning of the era of oxygenic photosynthesis. Given the great ecological success of diatoms in the modern world, it is important to understand the genetic basis of their success, and thus their possible responses to changing conditions in the future. The investigators, their postdoctoral fellows, and graduate students will participate in a summer program to train science teachers and provide them with curriculum support on the importance of diatoms in the worlds oceans and the modern genomic approaches to studying these important members of the phytoplankton community. The project will also support and sponsor undergraduate research by recruiting summer intern students from the local junior colleges as well as from the home institution of the investigators.