The Biological Bulletin, Vol 181, Issue 3 459-462, Copyright © 1991 by Marine Biological Laboratory

PHYSIOLOGY

Biological Activity of Biosynthetic Rainbow Trout Growth Hormone in the Eastern Oyster, Crassostrea virginica

K. T. Paynter and T. T. Chen
Department of Zoology, University of Maryland, College Park, Maryland 20742

Juvenile oysters were exposed to seawater containing 10-9, 10-8, and 10-7 M biosynthetic rainbow trout growth hormone (rtGH); the treatment was applied for one five-hour period per week for five weeks. At the end of the five weeks, the animals treated with the two highest concentrations of hormone were significantly longer and had dry tissue weights 50% greater than did the lowest treatment group or the control group. Continuing in vitro experiments on isolated oyster tissue showed that the hormone treatment significantly increased oxygen consumption. Boiled hormone had no effect. In both sets of experiments (whole animals and isolated tissues), the % dry wt (dry wt/wet wt) was significantly higher in all animals and tissues that responded to rtGH. The results demonstrate that rtGH has biological activity in oyster tissues, and this activity may be directly associated with growth regulation in the whole animal. The results further show that bivalve growth is not directly limited by environmental parameters.