Colleen Durkin

I am interested in the mechanisms used by phytoplankton to survive in different environments and their interactions with other organisms. I am excited to combine genome sequence information with lab and field experiments to further understand these processes. For my Master's work I am investigating the role of chitin in diatom ecology. Chitin is the most abundant polymer in the marine environment and several diatom genera are known to produce long chitin fibers. This chitin can make up 18% of their cellular nitrogen and 30% of their biomass. These extensions can also alter their interactions with zooplankton. Diatom genome sequencing has revealed a complicated array of chitin related genes for synthesis, binding, and breaking down chitin. I would like to use these genes to figure out how, when, and why chitin is important to diatom survival. Because chitin synthesis requires nitrogen and iron, the role of chitin producing organisms might change in different nutrient environments. The reasons for chitin use might be directly related to the diatom cell (for increased drag or structural support), or related to interactions with other organisms. Chitin spines change the effective size of a diatom cell, altering the trophic level of its predators. Also, the enzymes used to degrade chitin might be used as a defense mechanism against fungal parasites whose cell walls are composed of chitin. I hope to clarify the role of chitin in diatoms by studying gene expression under a variety of lab conditions. I also hope to apply these molecular methods to environmental samples taken along the equatorial Pacific.