Regulation of Proline Synthesis in Osmotic Response

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Research will focus on the biochemical and molecular mechanisms by which the marine copepod Tigriopus californicus responds to changes in environmental salinity. This species, like many others, is known to accumulate high intracellular concentrations of proline, a non- essential amino acid. The mechanisms regulating proline synthesis in response to osmotic stress in higher organisms remain to be determined. Previous work has shown that one regulatory site for induction of proline synthesis lies within the first two steps of the pathway between glutamate and proline; the current work will concentrate on this pathway. The goals of the proposed work are to elucidate the molecular mechanisms underlying this regulation and to determine why such regulation fails among some interpopulation hybrids. Primary objectives are: (1) to isolate (clone) the genes encoding the first two enzymes in the proline synthesis pathway, (2) to determine the normal pattern of regulation of these genes during osmotic response, (3) to screen interpopulation hybrid lines for aberrant regulation of proline synthesis at the biochemical level, and (4) to use the cloned genes as probes for determining the mechanism underlying hybrid breakdown in proline synthesis.