Two characteristics of diatoms that influence biogeochemical cycles are their high productivity and their unique silica cell walls. As a result, diatoms control the silicon cycle in the ocean and couple the carbon and silicon cycles. The largest particle export in the ocean is associated with sinking diatoms, which sequesters carbon into the deep ocean. My research is motivated by the complicated factors that influence whether diatoms bloom, how much silica they incorporate into their cells, and their tendency to sink. I am identifying which genes are involved in cell wall formation and how they respond to different nutrient conditions. This involves comparing gene content among diatom genomes, measuring gene expression in controlled lab experiments, and correlating changes in gene expression with changes in cell wall physiology. I am also applying what we learn about these genes in lab experiments to understanding natural populations. My goal is to use these genes to directly measure how diatoms in the ocean are responding in a particular environment. This will help us to identify which diatoms are responding, how they are changing their physiology, and under what conditions. Ultimately, this type of information will help us understand the conditions, timing, and community composition that most influence biogeochemical cycles.
Durkin, C.A., T. Mock, E.V. Armbrust. 2009. Chitin in diatoms and its association with the cell wall. Eukaryotic Cell 8:1038-1050
1. Identifying shared genes among diverse diatoms that are likely associated with the cell wall, and measuring gene expression in different nutrient limiting conditions. Genes found among diverse lab diatoms will be easier to find in diverse field populations.
Franzika Lutz and Tiffany Truong and two undergrads helping with this project.
2. Measuring diatom cell wall changes along the Line P transect in the subarctic North Pacific using both a silica stain (PDMPO) and gene expression.
Adrian Marchetti and Rhonda Morales collecting water from the CTD on the JP Tully in June 2008
3. Measuring community responses to different silicic acid concentrations along the Washington and Oregon Coasts with the CMOP program.
Sara Bender and Jarred Swalwell deploying a CTD in rough seas aboard the RV New Horizon in May 2009.