James B. Claiborne, Ph.D.
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Visiting Faculty, Georgia Southern University
Environmental Stress Biology
Ph.D., Univerisity of Miami, Biology (Physiology), 1981
B.S., Florida State University, Biology, 1977
Professor, Department of Biology
Georgia Southern University
We conduct research on a variety of bony fish and sharks, studying the physiological systems involved with the regulation of salts, water and pH in aquatic organisms. In a fashion analogous to the mammalian kidney, fish use their gills to transfer ions between their blood and the surrounding water. Our experiments examine these systems both in vivo and at the molecular level.
Our current NSF project focuses on the molecular and immunological detection of the RNA and protein(s) which allow these fish to excrete hydrogen in exchange for external sodium across the gills. Our laboratory was the first to demonstrate the presence of this Na /H
antiporter in the fish gill and we are now in the process of determining the distribution and regulation of this protein during physiological challenges to the animal.
The molecular and biochemical physiology of H+ excretion in the gills of marine fish.
The long-range goal of Dr. Claiborne’s research is to understand the role of gill membrane ion exchange systems in fish acid-base and ion regulation. The hypothesis is that Na+/H+ antiporters of the NHE family are located within the branchial epithelium and play an important role in compensating systemic acid-base stress and maintaining ion balance. Specific aims of the current NSF project are to
- determine the presence and cellular distribution of Na+/H+ antiporter ortholog NHE3 expression in gill tissue of stenohaline marine, freshwater and a euryhaline teleosts
- characterize the effects of systemic acid-base stress or variations in environmental salinity on gill NHE3 expression and distribution
- perform a functional analysis of fish NHE2 and NHE3 transfected and expressed in cell culture.
Examples of undergraduate projects include the in vivo detection of ammonia and acid-base transfers in the killifish adapted to salt and freshwater; the measurement of mRNA expression of NHE2 and NHE3 using quantitative PCR; and immunohistochemical localization of NHE proteins using light and laser confocal microscopy with fish-specific antibodies against the transporter of interest.