This award supports Professor Gregory Ahearn and two graduate students of the University of Hawaii to collaborate with Professor Helmut Wieczorek of the University of Munich in a study of cation transport by crustacean gastrointestinal and renal cells. Professor Wieczorek is an expert in molecular techniques for investigating the mechanism of ion regulation, particularly potassium secretion, by intestinal epithelial cells in insects. His current research focuses on the physiological properties of the cation antiporter protein in the secretory process. Dr. Ahearn's group has developed complementary expertise in applying radioisotopic tracer methods to assess the exchange kinetics of the antiporter protein in crustacea. The cooperating U.S. and German groups will link their research effort through reciprocal exchanges of graduate students for two three month periods per year. This should be an effective way to transfer their complementary expertise in molecular biology and transport physiology studies, and to save time and other resources in pursuing their research goal. This collaborative work is directly related to and enhances Dr. Ahearn's ongoing NSF-funded research on the transport physiology and molecular biology of the invertebrate cation exchange process. Sodium-proton exchange is an important physiological process which regulates intracellular pH and cell volume. While this fundamental ion movement occurs in similar fashion across the plasma membrane of both vertebrate and invertebrate cells, it is effected by very different exchange proteins. The molecular structure and function of the vertebrate exchange proteins or `transporters` are now well understood, but we know very little about the analogous sodium and calcium transporters in invertebrates. In crustacea, for example, such transport proteins are involved in the processes of food digestion, heavy metal sequestration and calcium regulation associated with the molt cycle. The analogous proteins in vertebrate cells has none of these functions. The collaboration between the University of Hawaii and the University of Munich will produce a major contribution to our knowledge of the molecular biology and the physiological roles of the sodium-proton transport protein in crustacea. Considering the significance of these transporters in the molt cycle and growth rate of the lobster, for example, one can imagine potential practical applications to aquaculture from this new knowledge.
