Laboratory of Aquatic Bioresources and Ecosystem, Field Science Center for Northern Biosphere, Division of Biosphere Science, Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido 060-0809, Japan.
Gen Comp Endocrinol. 2011 Jan 15;170(2):222-32. doi: 10.1016/j.ygcen.2010.02.003. Epub 2010 Feb 6.
The amazing abilities of Pacific salmon to migrate long distances from the ocean to their natal streams for spawning have been investigated intensively since 1950's, but there are still many mysteries because of difficulties to follow their whole life cycle and to wait their sole reproductive timing for several years. In my laboratory, we have tried to clarify physiological mechanisms of homing migration in Pacific salmon, using four anadromous Pacific salmon (pink, Oncorhynchus gorbuscha; chum, Oncorhynchus keta; sockeye, Oncorhynchus nerka; masu, Oncorhynchus masou) in the north Pacific Ocean as well as two lacustrine salmon (sockeye and masu) in Lake Toya and Lake Shikotsu, Hokkaido, Japan, where the lakes serve as a model "ocean". Three different approaches from behavioral to molecular biological researches have been conducted using these model fish. First, the homing behaviors of adult chum salmon from the Bering Sea to Hokkaido as well as lacustrine sockeye and masu salmon in Lake Toya were examined by means of physiological biotelemetry techniques, and revealed that salmon can navigate in open water using different sensory systems. Second, the hormone profiles in the brain-pituitary-gonadal (BPG) axis were investigated in chum salmon and lacustrine sockeye salmon during their homing migration by means of hormone specific time-resolved fluoroimmunoassay (TR-FIA) systems, and clarified that salmon gonadotropin-releasing hormone (sGnRH) plays leading roles on homing migration. Third, the olfactory functions of salmon were studied by means of electrophysiological, behavioral, and molecular biological techniques, and made clear that olfactory discriminating ability of natal stream odors. These results have discussed with the evolutional aspects of four Pacific salmon, sexual differences in homing profiles, and the possibility of dissolved free amino acids (DFAA) as natal stream odors for salmon.
自 20 世纪 50 年代以来，人们对太平洋三文鱼从海洋洄游到其出生地进行产卵的惊人能力进行了深入研究，但由于难以跟踪它们的整个生命周期并等待它们唯一的繁殖时机长达数年，仍然存在许多谜团。在我的实验室里，我们尝试使用北太平洋的四种洄游性太平洋三文鱼（粉三文鱼、Oncorhynchus gorbuscha；银三文鱼、Oncorhynchus keta；红三文鱼、Oncorhynchus nerka；大麻哈鱼、Oncorhynchus masou）以及日本北海道的洞爷湖和支笏湖的两种湖栖三文鱼（红三文鱼和大麻哈鱼）来阐明太平洋三文鱼归洄洄游的生理机制，这些湖是“海洋”的模型。我们使用这些模式鱼从行为到分子生物学研究进行了三种不同的方法。首先，通过生理生物遥测技术研究了从白令海到北海道的成年银三文鱼以及洞爷湖的湖栖红三文鱼和大麻哈鱼的归洄行为，结果表明三文鱼可以使用不同的感觉系统在开阔水域中导航。其次，通过激素特异性时间分辨荧光免疫分析（TR-FIA）系统研究了洄游过程中银三文鱼和湖栖红三文鱼的脑垂体性腺（BPG）轴中的激素谱，并阐明了三文鱼促性腺激素释放激素（sGnRH）在归洄洄游中起主导作用。第三，通过电生理学、行为学和分子生物学技术研究了三文鱼的嗅觉功能，并明确了对出生地气味的嗅觉辨别能力。这些结果与四种太平洋三文鱼的进化方面、归洄洄游的性别差异以及作为三文鱼出生地气味的游离氨基酸（DFAA）的可能性进行了讨论。
