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Monday, June 23, 2008
10:00 AM - 11:00 AM
CNLS Conference Room (TA-3, Bldg 1690)

Seminar

Molecular and Genomic Approaches to Nutrient Metabolism in Aquatic Microbes

Andrew Allen
J. Craig Ventor Institute, San Diego CA

Genome enabled approaches to cellular physiology, ecology, and biogeochemistry of marine microbes are having a major impact on our understanding of microbial life in the marine environment. Processes such as siderophore or nitrate assimilation which were previously believed to be carried out exclusively by prokaryotes or eukaryotes respectively are now known to occur in organisms from different kingdoms. New information coming from functional and meta-genomics studies regarding gene repertoire and cellular trade-offs that govern constraints on microbial life in the ocean are having a profound impact on our view of various biogeochemical processes. For example, whole genome sequence analysis for the centric diatom Thalassiosira pseudonana and the pennate diatom Phaeodactylum tricornutum has revealed that diatoms contain genes and pathways that were known previously in only in prokaryotes and metazoans and are novel in photosynthetic eukaryotes. A complete urea cycle is an example of such a pathway that was known previously only in vertebrate lineages. Various reverse genetics based approaches are beginning to provide clues regarding the integration of a metazoan-type urea cycle into the photosynthetic life style of diatoms. Many aspects of nitrogen (N) and (Fe) metabolism and cell signaling appear to be linked in diatoms. Understanding the factors which control and regulate nitrogen (N) and (Fe) iron sensing and metabolism in marine phytoplankton and bacteria is essential for understanding and modeling the ecology and biogeochemistry of plankton communities. Comparative and functional genomics approaches are currently being utilized in order to understand the molecular evolution and metabolic ecology of marine microbes and to identify regulatory and metabolic networks that control the extraordinary ecological flexibility and dominance of diatoms and other marine microbes.

Host: John Pearson, T-10, 7-7585, pearson@lanl.gov