2005 Fiscal Year Final Research Report Summary
Photoperiodic signal transduction in the brain regulating gonadal maturation in fish
| Project/Area Number |
16580158
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
General fisheries
|
|---|
| Research Institution | Kitasato University |
|---|
Principal Investigator |
AMANO Masafumi Kitasato University, School of Fisheries Sciences, Associate Professor, 水産学部, 助教授 (10296428)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
IIGO Masayuki Utsunomiya University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (10232109)
|
|---|
| Project Period (FY) |
2004 – 2005
|
| Keywords | masu salmon / melatonin / receptor / brain / pituitary / in situ hybridization / cDNA cloning / daily rhythm |
|---|
| Research Abstract |
1.Melatonin binding sites were detected in the preoptic area, pretectal area, optic tectum and pituitary gland of masu salmon by in vitro autoradiography.
2.The changes in melatonin binding sites in the brains of masu salmon under artificial light-dark (LD), constant light (LL) and constant dark (DD) conditions were examined by radioreceptor assay (RRA). First, fish were reared under a long (LD 16:8) or short (LD 8:16) photoperiod. The total binding capacity (Bmax) exhibited no daily variations. The affinity (Kd) slightly, but significantly, changed under LD 8:16. Next, fish reared under LD 12:12 were exposed to LL or DD. No significant differences were observed in the Kd and the Bmax between the two groups, and the Kd and the Bmax exhibited no circadian variation either in the LL or DD groups. These results indicate that light conditions have little effect on melatonin binding sites in the masu salmon brain.
3.To obtain a better understanding of the roles of melatonin in the regulation of photoperiodic signaling, the effects of photoperiodic treatment on melatonin binding sites were examined. Fish were divided into a LD 8:16 and a LD 16:8 group in June. Kd and Bmax did not significantly change in both groups and no significant differences were observed between the groups at each sampling point.
4.Melatonin receptor subtype (Mella) was cloned from the brain and retina of masu salmon.
5.Melatonin receptors were expressed in the preoptic area, pretectal area and optic tectum of the masu salmon brain.
6.We showed a possibility that melatonin stimulate the release of sGnRH from the cultured slice of hypothalamus of masu salmon.
7.We showed a possibility that melatonin stimulate the release of GTH from the cultured pituitary of masu salmon and sockeye salmon.
8.Melatonin binding sites were detected in the eye, tesitis and ovary of masu salmon by RRA.
|
