Areas of Expertise
Research: Biology, anatomy, comparative physiology, membrane physiology, aquaculture, crustaceans, fishes, environment, aquaculture and nutrition
Teaching: Physiology, Anatomy & Physiology
Ph.D: Arizona State University (1970)
Post-Doctoral Work: University of Copenhagen (1972)
Sabbatic from the University of Hawaii to the University of Zurich, Switzerland (1983)
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. In the past, 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. Our most recent research direction is to study how ocean acidification, from climate change, affects calcium uptake from seawater and freshwater by animals with a calcium carbonate skeleton. Our hypothesis is that increased protons compete with calcium ions in solution and prevent their uptake into animal tissues, slowing the transfer of calcium to sites of skeletal formation and increasing mortality as a result.
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
Likely, R., Johnson, E., and Ahearn, G. A. (2015) Functional characterization of a putative disaccharide membrane transporter in crustacean intestine. J. Comp. Physiol. B. 185:173-183.
Peterson, M., Lane, A., and Ahearn, G. A. (2015) Analysis of glycylsarcosine transport by lobster intestine using gas chromatography. J. Comp. Physiol. B. 185: 37-45.
Duka, A. and Ahearn, G. A. (2014) Comparative cation dependency of sugar transport by crustacean hepatopancreas and intestine . Biology Open. 3: 635-643
Abdel-Malak, R. and Ahearn, G. A. (2014) Regulation of transmural transport of amino acid/metal conjugates by dietary calcium in crustacean digestive tract. J. Exp. Zool. 321A: 135-143.
Omran, A., Ahearn, G. A., Bowers, D., Swensen, J., Coughlin, C. B. (2013) Metabolic effects of sucralose on environmental bacteria. J. Toxicology, Vol. 2013, Article ID 372986, http//dx.doi.org/10.1144/2013/372986.
Duka, A. and Ahearn, G. A. (2013) L-Leucine, L-methionine, and L-phenylalanine share a Na+/K+-dependent amino acid transporter in shrimp hepatopancreas. J. Comp. Physiol. B. 183(6): 763-771.
Obi, I. E., Sterling, K. M. and Ahearn, G. A. (2013) K+-dependent 3H-D-glucose transport by hepatopancreatic BBMV of the marine shrimp, Litopenaeus setiferus. J. Comp. Physiol. B. 183:61-69.
Simmons, T., Mozo, J., Wilson, J., and Ahearn, G. A. (2012) Cation-dependent nutrient transport in shrimp digestive tract. J. Comp. Physiol. B. 182: 209-216.
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 co-transporter. J. Exp.Zool. 315: 465-475.
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.