Hormonal control of migration in salmon

内分泌系统在控制鱼类洄游的各个方面都有重要作用。人们普遍认为，在鲑鱼中，催乳素是淡水适应所必需的激素，而生长激素则是海水适应所必需的激素。然而，我们不知道这些激素在洄游鱼类中的作用方式，主要是因为缺乏同源激素。分子生物学的最新进展使微生物合成所谓的重组激素成为可能，这反过来又使我们能够进行受体研究，如放射性受体测定（RRA）。因此，在本项目中，我们试图将分子技术应用于鲑鱼洄游的内分泌机制研究。由于重组鲑鱼生长激素是可用的，一个放射性受体测定系统是相当容易建立，以检查其动力学的生理变化。相反，重组鲑鱼催乳素是不可用的，因此，罗非鱼的激素是可用的，以建立催乳素RRA。

The endocrine systems have important roles in controls of various aspects of fish migration. It is well accepted that, in salmonid fish, prolactin is a hormone necessary for fresh water adaptation, while growth hormone is responsible for seawater adaptation. Nonetheless, we do not know modes of actions of these hormones in migratory fish, mainly because of a lack of homologous hormones. Recent progress in molecular biology now makes it possible to have micro-organisms synthesize so-called recombinant hormones which in turn allow us to conduct receptor studies, such as a radio receptor assay (RRA). In the present project, we therefore tried to apply molecular techniques in a study on endocrine mechanisms of salmon migration. Since recombinant salmon growth hormone is available, a radio receptor assay system was rather easily established to examine physiological changes in its kinetics. Contrary, recombinant salmon prolactin is not available, so that tilapia whose hormone is available was used to establish prolactin RRA.