Hormonal control of migration in salmon

内分泌系统在鱼类洄游的各个方面起着重要的控制作用。人们普遍认为，在鲑科鱼类中，催乳素是适应淡水所必需的激素，而生长激素则负责适应海水。然而，我们不知道这些激素在洄游鱼类中的作用模式，主要是因为缺乏同源激素。分子生物学的最新进展现在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，例如无线电受体测定（RRA）。因此，在本项目中，我们尝试应用分子技术研究鲑鱼洄游的内分泌机制。由于重组鲑鱼生长激素是可用的，因此很容易建立一个无线电受体测定系统来检查其动力学中的生理变化。而重组鲑鱼催乳素缺乏，因此利用有催乳素激素的罗非鱼建立催乳素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.