Collaborative Research: A Proteomic approach to understanding cytoprotective biogenic sulfur production in sea-ice diatoms.

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Intellectual Merit: Biogenic sulfur compounds such as dimethylsulfide (DMS) and its precursor dimethylsulfoniopropionate (DMSP) are climatically important compounds due to their effects on the Earth's radiation budget. Sea ice algal communities are significant producers of DMSP and DMS, and paradoxically, these communities are also often dominated by diatoms, which in pelagic environments produce negligible DMSP and DMS. Using a laboratory-based approach involving both semi-continuous batch cultures and chemostats, a series of incubation experiments will be conducted that mimic the extreme environmental conditions found within sea-ice. These experiments will reveal the stress physiology and cold adaptation of sea-ice diatoms. In parallel with the physiological analyses, a novel approach using proteomics tools, such as 2-D Difference Gel Electrophoresis will be used to determine which proteins are differentially expressed during acclimation to the environmental stressors. Artificial neural networks will assess the relationship between changes in DMSP production and changes in protein abundances, and find biomarker information on the pathways regulating cold acclimation, stress avoidance and DMSP production. Broader Impacts: At a global level, the proposed study would improve scientific understanding of what factors cause the high DMSP production in ice-algal communities and subsequently how DMSP production in sea ice diatoms could change as a result of global warming. As part of a high school outreach program, we will develop an interactive website to disseminate information on polar ecosystems and the role of the sulfur cycle in climate modulation. The proposed study will also provide support for a Ph.D. level student who will be directly involved in the proteomics component of the study and a Masters level student will be directly involved in the physiology component of the study. In addition, high school students involved in the outreach program and students from the REU program at the Grice Marine Laboratory (College of Charleston) will be offered opportunities to participate in the research effort.