Areas of Expertise
Research: Biology, anatomy, physiology, aquaculture, crustaceans, environment, aquaculture and nutrition
Teaching: Physiology, Anatomy & Physiology
Ph.D: Arizona State University (1970)
Post-Doctoral Work: University of Copenhagen
My laboratory is using electrophysiology, membrane vesicle techniques, cell culture, dissociated tissue cell suspensions, and molecular biology to investigate the physiology of molecular transport by epithelial cell membranes of fish and crustacean gastrointestinal and renal organs. Over the past 25 years we have used a variety of experimental techniques to investigate membrane transport processes in the crustacean gastrointestinal tract and antennal glands for nutrients, ions, and heavy metals. For the past 12 years, we have investigated the mechanisms of sugar, amino acid, and vitamin transport in the fish intestine as a scientific cooperative exchange program with the University of Lecce, Italy. Recently we have focused our work on investigating ion transport processes of crustacean epithelial cells and have discovered a novel 2Na+/1H+ transport protein in crustacean cell membranes which significantly differs physiologically from its mammalian counterpart. We are currently investigating this interesting invertebrate protein with molecular biology techniques which will allow us to identify the gene that codes for the protein and compare it to the DNA sequences responsible for analogous proteins in vertebrates. In addition, we have recently shown that this transporter is involved in heavy metal uptake from the environment and are currently investigating the interaction of this carrier system with epithelial detoxification processes for a variety of heavy metals.
Recipient of The John A. Delaney Endowed Presidential Professorship (2008-2011)
Grants and Contracts Awarded
US Department of Agriculture: Synergistic Absorption of Essential Amino Acids and Metals by Shrimp Digestive Tract - $350,000 (2010)
National Science Foundation: RUI: Heavy Metal Detoxification in Crustaceans - $144,907 (2004)
Publications & Presentations
Obi, I., Wells, A.L., Ortega, P., Patel, D., Farah, L., Zanotto, F. P. and Ahearn, G. A. (2011) 3H-L-leucine transport by the promiscuous crustacean dipeptide-like cotransporter. J. Exp.Zool. (in press).
Obi, I. E., Sterling, K. M., and Ahearn, G. A. (2011) Transepithelial D-glucose and D-fructose transport across the American lobster, Homarus americanus, intestine. J. Exp. Biol. 214: 2337-2344.
William R. Harvey, Bernard A. Okech, Paul J. Linser, David A. Price, James J. Becnel,Gregory A. Ahearn, and Kenneth M. Sterling. (2010) H+ V-ATPase-energized transporters in brush border membrane vesicles from whole larvae of Aedes aegypti. J. Insect Physiol. 56:1377-1389..
Sterling, K. M. and Ahearn, G. A. (2011) Glucose and fructose uptake by Limulus polyphemus hepatopancreatic brush border and baso-lateral membrane vesicles - Evidence for Na+-dependent sugar transport activity. J. Comp. Physiol. B. .181: 467-475.
Ahearn, G. A. (2010) Heavy metal transport and detoxification in crustacean gastrointestinal and renal epithelial cells, IN: J. Koropatnick and R. K. Zalups, eds, Cellular and Molecular Biology of Metals, Taylor and Francis, CRC Press, pp.295-326.
Sterling, K. M., Roggenbeck, B., and Ahearn, G. A. (2010) Dual control of cytosolic metals by lysosomal transporters in lobster hepatopancreas. J. Exp. Biol. 213: 769-774.
Ahearn, G. A., Sterling, K. M., Mandal, P. K.. and Roggenbeck, B. (2009) Heavy metal transport and detoxification by crustacean epithelial lysosomes, IN: G. A. Gerencser, ed., Comparative epithelial transport processes, The Humana Press, Inc., pp. 49-71.
Gerencser, G. A. and Ahearn, G. A. (2009) Divalent anion transport in crustacean and molluscan gastrointestinal epithelia, IN: G. A. Gerencser, ed., Comparative epithelial transport processes, The Humana Press, Inc., pp. 29-47.