9629572 Powers Differences in the expression of genes that encode intracellular enzymes are a particularly important potential source of genetic diversity for species; these differences may provide the kind of genetic plasticity that allow adaptation to large changes in environmental parameters, like temperature, salinity, and others. While studies documenting changes in gene expression in relation to such environmental parameters are few, studies delineating the mechanisms responsible for these changes are even fewer. The present research project will provide one of the very few detailed studies of the molecular mechanisms that differentially regulate the expression of one of these loci. Dr. Powers and his colleagues take advantage of the well characterized model teleost, Fundulus heteroclitus, and an equally well characterized gene system, i.e., the intracellular enzyme common to heart and other aerobic red muscle tissue, the lactate dehydrogenase-B gene (Ldh-B). Because the teleost model is distributed along the east coast of North America, i.e., from Newfoundland to Florida, populations at the extremes of the species range are exposed to very different environmental temperatures. Since fish are "cold blooded" animals, this temperature difference could have a profound effect on them, if there were no compensatory adaptive changes. One such change already uncovered is a difference in gene expression of Ldh-B between fish from the cold waters of Maine and those from the warm waters of Florida. The proposed research will delineate the detailed molecular mechanisms underlying this difference in gene regulation of Ldh-B. Factors involved in the regulation of the Ldh-B gene will be identified and variation in these factors and their functional consequences will be examined using a wide variety of modern molecular techniques. Identifying the molecular mechanisms underlying the variation in transcriptional regulation between populations of this model teleost, is a first important step toward a detailed understanding of the evolution of gene regulation, in general. In addition to addressing the basic research issue of the molecular mechanisms that underlie direct evolutionary change at the regulatory level, this research will also provide important fundamental information about the regulation of a critical enzyme system in intermediate metabolism that has not been previously determined. The new knowledge uncovered about the details of Ldh-B gene regulation will provide an important scientific basis for a better understanding of the regulation of genes encoding metabolic enzymes. This knowledge can be used to provide insight about other organisms, including humans. This study will also provide gene regulation information that may eventually be useful in the genetic engineering of disease-resistant, fast growing, environmentally safe, fish for the aquaculture industry in the future.
