Meeting Abstract
19.5 Sunday, Jan. 4 NEUROENDOCRINE CONTROL OF SEX CHANGE IN THE ROCK HIND, Epinephelus adscensionis KLINE, RJ*; HOLT, GJ; KHAN, IA; Univ. of Texas Marine Science Institute; Univ. of Texas Marine Science Institute; Univ. of Texas Marine Science Institute rjkline@mail.utexas.edu
The following research is being conducted to investigate the linkage between behavioral and gonadal sex change in hermaphroditic fish. In fish, the brain produces both arginine vasotocin (AVT) and gonadotropin releasing hormone (GnRH) within the preoptic area anterior hypothalamus (POAH). Both of these hormones have been implicated in sexual change in hermaphroditic species of wrasse and goby. However, little is known about these hormones regulating sex change in grouper species. In our laboratory, a small protogynous grouper, rock hind Epinephelus adscensionis, is being used as a model to investigate neuroendocrine control of sex change. We have placed rock hind in small social groups and have successfully induced sex change by removing the dominant male from the group. Video documentation of male type behavior will be presented demonstrating striking but temporary changes in color pattern during dominance displays. The AVT V1a receptor has been identified as a key receptor mediating behavioral sex change. In other species, blocking this receptor by an antagonist inhibits male type behavior. In the present study, AVT V1a receptor cDNA was isolated and cloned from rock hind brains. Based on the predicted amino acid sequence, an AVT V1a receptor antibody specific to rock hind was developed. This antibody recognizes a single band of the expected size (~ 45 kDa) in Western blots from rock hind brain membrane fractions. The antibody is being used to quantify changes in AVT receptor levels in the POAH from male and female rock hind and to examine changes in AVT V1a receptor expression during behavioral sex change. Ongoing research will also identify the relationship of AVT to GnRH in the POAH using co-localization and quantification of mRNA in fish undergoing sex change.
