1998 Fiscal Year Final Research Report Summary
Endocrinological Research on Hormonal Control of Salmon Homing Migration
| Project/Area Number |
09460082
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
General fisheries
|
|---|
| Research Institution | HOKKAIDO UNIVERSITY |
|---|
Principal Investigator |
UEDA Hiroshi Fac.of Fish., Hokkaido Univ., Asso.Pro., 水産学部, 助教授 (00160177)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KAERIYAMA Masahide School of Eng., Hokkaido Tokai Univ., Pro., 工学部, 教授 (80305937)
NAITO Yasuhiko National Institute of Polar Research, Po., 教授 (80017087)
SHOJI Takayuki Grad.School of Pharm.Sci., Hokkaido Univ., Inst., 大学院・薬学研究科, 助手 (00241349)
URANO Akihisa Grad.School of Sci., Hokkaido Univ., Pro., 大学院・理学研究科, 教授 (00142232)
HARA Akihiko Fac.of Fish., Hokkaido Univ., Pro., 水産学部, 教授 (40091483)
|
|---|
| Project Period (FY) |
1997 – 1998
|
| Keywords | Chum salmon / Lacustrine sockeye salmon / Lacustrine masu salmon / Homing migration / Gonadal maturation / Gonadotropin-releasing hormone / Gonadotropin / Steroid hormone |
|---|
| Research Abstract |
The salmon homing migration is closely related to gonadal maturation, which is regulated mainly by the brain-pituitary-gonadal axis. In particular, gonadotropin-releasing hormone (GnRH) produced from the olfactory system and the preoptic area, gonadotropin (GtH) from pituitary gland, and gonadal steroid hormones seem to play important roles in both the homing migration and gonadal maturation in salmonids. The present research presents the activation of salmon GnRH (sGnRH) gene in the preoptic area, the activation of GtHII gene in the pituitary gland, and the increase of serum 17alpha, 20beta-dihydroxy-4-pregnen-3-one (DHP) levels in chum salmon (Oncorhynchus keta) during the homing migration. The intramuscular GnRH analog (GnRHa) implantation is efficient to shorten homing duration in lacustrine, maturing sockeye salmon (0. nerka) of both sexes in early spawning season. The implantation causes dramatic activation of GtHII gene in the pituitary gland, and significant increases of serum DHP level. DHP implantation also shortenes homing duration in females, but not in males. The electrophysiological study suggests that the olfactory organ of masu salmon (0. masou) can discriminate the composition and concentration of amino acids in various freshwater odors regardless of sex and sexual maturity. The micro datalogger analysis hypothesize that temperature is not an important parameter for upstream migration in lacustrine masu salmon during the spawning season.
|
