Molecular cloning of gonadotropin genes and their regulation of expression.

Research Project

Project/Area Number	06660229
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	General fisheries
Research Institution	The University of Tokyo
Principal Investigator	KOBAYASHI Makito The University of Tokyo, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (30183809)
Project Period (FY)	1994 – 1995
Project Status	Completed (Fiscal Year 1995)
Budget Amount *help	¥1,900,000 (Direct Cost: ¥1,900,000) Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000) Fiscal Year 1994: ¥1,100,000 (Direct Cost: ¥1,100,000)
Keywords	goldfish / gonadotropin gene / gene expression / reproductive endocrinology of fish / cDNAクローニング
Research Abstract	As in other vertebrates, reproductive activities in fish is regulated by an endocrine system, consisting of brain-pituitary-gonad axis. It had been thought that fish had only single type of pituitarty gonadotropin (GTH), but recently two types of GTH were identified in salmon.Althogh cyprinid species have been used as model species for the study of reproductive endocrinology of fish, it is not well studied on the regulation of GTH synthesis in these species. For the study of regulatory mechanism of GTH synthesis or GTH gene expression in the pituitary, specific cDNA probes are necessities. I cloned cDNA of GTH subunits (I and II) from the pituitary of goldfish last year and obtained specific probes for goldfish GTH. This year, I examined GTH gene expression during gonadal maturation by Norhtern blot analysis. Unlike salmonids in which GTHI dominates during eary stage of gonadal development and GTHII in maturational stage, expression of both GTHI and II showed an increase with the progression of gonadal maturation in goldfish. The results may reflect different patterns of spawning cycle between salmonids and goldfish ; salmonids spawn once during their spawning period, whereas goldfish spawns several times. I also examined effects of water temperature on GTH gene expression. Expression of GTHI was higher at low temperature and that of GTHII at moderate temperature. These results suggest that water temperature is involved in the regulation of differential expression in goldfish GTH genes.