| Project/Area Number |
07404046
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (A)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
生物形態・構造
|
|---|
| Research Institution | HOKKAIDO UNIVERSITY |
|---|
Principal Investigator |
ANDO Hironori Graduate School of Sci., Hokkaido University, Assist.Pro., 大学院・理学研究科, 助手 (60221743)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KAERIYAMA Masahide Facalty of Engineering, Hokkaido Tokai University, Pro., 工学部, 教授 (80305937)
UEDA Hiroshi Facalty of Fish., Hokkaido University, Asso.Pro., 水産学部, 助教授 (00160177)
ITO Etsuro Graduate School of Sci., Hokkaido University, Asso.Pro., 大学院・理学研究科, 助教授 (80203131)
URANO Akihisa Graduate School of Sci., Hokkaido University, Pro., 大学院・理学研究科, 教授 (00142232)
|
|---|
| Project Period (FY) |
1995 – 1998
|
| Keywords | Migration / Salmonid fish / Neurohormone / Pituitary hormone / Gene expression / GnRH / Spawning behavior / Preoptic nucleus |
|---|
| Research Abstract |
The spawning migration is a kind of innate behavior which is essential for successful reproduction in salmon. To realize a genetic program of the behavior. we have examined molecular basis of neuro-endocrine mechanisms of salmon migration. Our research has been focused mainly on the following three points ; 1)Changes in expression levels of hypothalamic and pituitary hormone genes during spawning migration, 2)Structural analysis of the neurohormone genes. 3)Roles of gonadotropin-releasing hormone (GnRH) in the control of spawning behavior. The results of this project are summarized as follows.
1. The levels in neurohypophysial hormone (NH) mRNAs decrease in the pre-spawning females. The sexual dimorphic expression of the NH genes suggests that the NH may be involved in reproductive behavior as well as osmotic regulation in the homing salmon. The gonadal and adrenocortical stroid hormones may be concerned in the control of the NH gene expression.
2. The expression of salmon GnRH (sGnRH) gene in the preoptic area increases during final maturation. The 5' upstream regions of the two sGnRH genes (sGnRH-I and-II) are distinctively divergent. The expression of gonadotropin alpha and IIbeta genes also. increases temporally in the final maturation, and is stimulated by the administration of genre.
3. The adminiatration of GnRH shortens duration of the homing migration. The GnRH may play roles in the stimulation of not only gonadal maturation but also migratory behavior.
The molecular neuroendocrine basis of spawning migration is considered to be mostly established at present. In the new project ''Moleclular neuroendocrine regulation of spawning migration in salmon", which is supported by the Grant-in-Aid for Specially Promoted Research, further investigations on the molecular mechanisms of neurohormone action in the control of salmon spawning migration will be progressively done.
|
