Research interests
Our laboratory utilizes many molecular biological techniques to study the effects of environmental toxicants on numerous biological processes. Of particular interest to our research laboratory are non-essential heavy metals and the effects such pollutants exert on essential metaleffects such pollutants exert on essential metal homeostasis.
Transgenic Zebrafish
Zebrafish have rapidly become a major model organism for the study of a variety of questions related to human health, including development, cancer, and the effects of toxicological agents. Their small size, low cost, and the ease of exposure to toxic compounds in the aquatic environment make them particularly attractive and tractable for toxicological studies. The above photographs are of transgenic zebrafish containing a green flourescent protein under control of a metallothionein gene promoter. The metallothionein protein binds heavy metals within the cell, and the promoter or "on/off" signal for this gene is highly responsive to increased intracellular heavy-metal concentrations. Thus when intracellular heavy-metal concentrations increase the metallothionein promoter is activated and "turns on" transcription of the green flourescent protein. Studies are underway to utilize this transgenic model as a sentinel organism for the indication of heavy-metal polluted water.
Another model our laboratory utilizes for the study of zinc homeostasis is the squirrelfish (Holocentrus adscensionis). The squirrelfish is a tropical coral reef fish that exhibits an ecxeptional zinc metabolism. this family of fish (Holocentridae) are able to sequester copious amounts of zinc in the liver and pass this zinc to the reproductive organs when needed for embryo development. By utilizing this zinc hyperaccumulator we are able to map several processes involved in zinc mediated metabolism.
Publications
Mayer, G.D., Berry, J.P., Patenaude, C.A., Walsh, P.J. Effect of lipopolysaccharides from Microcystis and Lyngbya on metal toxicity in Fundulus Heteroclitus. Bull. MDIBL 43: 143-44 (2004)Mayer G.D., Leach D.A., Kling, P., Olsson, P.-E. and Hogstrand C. Activation of the rainbow trout metallothionein-A promoter by silver and zinc. Comp. Biochem. Physiol.-B 134: 181-188 (2003).
Walsh, P.J., Mayer, G.D., Bookman, R.J., Zaias, J., Abraham, W., Bordelais, A., Baden, D.G. Toxicogenomic effects of Marine Brevetoxins in Liver and Brain of Mouse. Comp. Biochem.Physiol.-B 136: 173-182 (2003).
Walsh, P.J., Mayer, G.D., Medina, M., Bernstein, M.L., Barimo, J., and Mommsen, T.P. A Second Glutamine Synthetase Gene with Expression in the Gills of the Ureotelic Gulf Toadfish (Opsanus beta). J.Exp.Biol. 206 (9): 1523-1533 (2003).
Thompson, E.D., Mayer, G.D., Balesaria, S., Walsh,P.J., and Hogstrand, C. Physiology and endocrinology of zinc accumulation during the female squirrelfish reproductive cycle. Comp. Physiol. Biochem. A-Molecular & Integrative Physiology 134 (4): 819-828 (2003)
Glover, C.N., Balesaria, S., Mayer, G.D., Thompson, E.D., Walsh, P.J., and Hogstrand, C. Intestinal zinc uptake in the marine teleosts, squirrelfish (Holocentrus adscensionis) and Gulf toadfish (Opsanus beta). Physiol. Biochem. Zool. 76(3): 321-330 (2003).
Thompson, E.D., Mayer, G.D., Walsh, P.J., and Hogstrand, C. Sexual maturation and reproductive zinc physiology in the female squirrelfish. J. Exp. Biol. 205: 3367-3376 (2002).
Galvez F., Mayer G.D., Wood C.M. and Hogstrand C. The distribution kinetics of waterborne silver-110m in juvenile rainbow trout. Comp. Biochem. Physiol. C 131: 367-378 (2002)
Thompson E.D., Olsson P.E., Mayer G.D., Haux C, Walsh P.J., Burge E., Hogstrand C. Effects of 17ß-estradiol on levels and distribution of metallothionein and zinc in squirrelfish. Am. J. Physiol. 280:R527-R535 (2001).
Thompson E.D., Olsson P.-E., Mayer G.D., Haux C., Walsh P.J. and Hogstrand C. (1998) Involvement of metallothionein in female squirrelfish reproduction. In: Metallothionein IV (Ed. C.D. Klaassen), pp. 157-165, Birkhäuser Verlag, Basel, Switzerland.
