SGER: Exploratory studies of marine microbes using nanoSIMS

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This Small Grant for Exploratory Research provides support for post doctoral research and training using NanoSIMS or nano scale secondary ion mass spectrometry. Nano SIMS is a state of the art approach for analyzing the distribution of metals and isotopic composition in biological materials at 50 nm resolution. Hence, one may examine the intracellular and intercellular distributions of relevant metals such as iron and molybdenum as well as the isotopic composition of many elements.This approach provides the means to reveal the intricacies of uptake and metabolism of these elements. The investigator has established a collaboration with Lawrence Livermore National Laboratory (LLNL) to explore the application of nanoSIMS for studies of marine microorganisms. While access time on the system is at a premium with many competing users, beam time has been made available to the investigator in 2007- 2008. This opportunity allows the post doc to undertake exploratory research with the nanoSIMS group at LLNL into biogeochemically and biologically oriented areas of relevance to marine ecosystems. These include the cellular distribution of biochemically important metals such Fe, Mo, Co and Zn in marine phytoplankton and bacteria as indicators of their cellular metabolism and physiology, the fine scale intra- and intercellular distribution of stable isotopes such as 13C and 15N as indicators of cellular function, and in enriched tracer studies in order to discern metabolism and metabolite exchange within and among cells.Processes of relevance are nitrogen fixation and nitrate uptake, vitamin B12 metabolism and carbonic anhydrase activity.The postdoctoral associate (Sophie Bonnet) will interact with several researchers at USC (Capone, Sanudo-Wilhelmy, Moffett, Hutchins, Nealson, Berelson) as well as the scientists and technicians at the Livermore Lab in undertaking experiments at the nanoSIMS facility.