SS2.03 Phytoplankton Ecology Using Molecular Approach
Date: Thursday, June 13, 2002
Time: 5:00:00 PM
Location: Colwood
 
SmithGJ, Moss Landing Marine Laboratories, Moss Landing, USA, jsmith@mlml.calstate.edu
Kudela, R, , Ocean Sciences Dept., UCSC, Santa Cruz, USA, kudela@cats.ucsc.edu
 
BIOINFORMATIC APPROACHES TO INVESTIGATION OF PHYTOPLANKTON METABOLISM: PATHWAY ANALYSIS OF PROLINE METABOLISM IN THE TOXIC DIATOM PSEUDO-NITZSCHIA MULTISERIES
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Continuous culture experiments with phytoplankton represent tractable systems for computational analysis of metabolism. Metabolite profiling of the quasi-steady-state conditions obtained permit modeling of associated biochemical pathways using generalized mass action (GMA) systems and related approaches. Hypothesis-driven model runs can help identify critical targets for gene expression studies. The development of a GMA model of proline (PRO) metabolism in P. multiseries will be described and used to characterize the dynamics of pathway intermediates under growth conditions supporting different levels of domoic acid (DA) biosynthesis. Analysis of intracellular free amino acid (FAA) pools in Si-limited cultures (Si/NO3 supply ratio of 0.1) revealed that DA content increased by over 100-fold in cells subjected to low Si (0.2/d) compared to high Si (1.2/d) supply rates. Cellular FAA, GLU and PRO contents did not exhibit significant trends over this range of growth rates whereas PON content increased by 2-fold. These observations are used to parameterize the GMA model in order to assess whether the accumulation of the potentially toxic intermediate of PRO catabolism, pyrroline-5-carboxylate, is correlated with DA biosynthesis.