Laboratory of Animal Physiology, Department of Applied Molecular Biosciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan.
Nat Commun. 2013;4:2108. doi: 10.1038/ncomms3108.
The pars tuberalis of the pituitary gland is the regulatory hub for seasonal reproduction in birds and mammals. Although fish also exhibit robust seasonal responses, they do not possess an anatomically distinct pars tuberalis. Here we report that the saccus vasculosus of fish is a seasonal sensor. We observe expression of key genes regulating seasonal reproduction and rhodopsin family genes in the saccus vasculosus of masu salmon. Immunohistochemical studies demonstrate that all of these genes are expressed in the coronet cells of the saccus vasculosus, suggesting the existence of a photoperiodic signalling pathway from light input to neuroendocrine output. In addition, isolated saccus vasculosus has the capacity to respond to photoperiodic signals, and its removal abolishes photoperiodic response of the gonad. Although the physiological role of the saccus vasculosus has been a mystery for several centuries, our findings indicate that the saccus vasculosus acts as a sensor of seasonal changes in day length in fish.
垂体的结节部是鸟类和哺乳动物季节性繁殖的调节中枢。尽管鱼类也表现出强烈的季节性反应，但它们没有解剖学上明显的结节部。在这里，我们报告鱼类的血管球囊是一个季节性传感器。我们观察到调控季节性繁殖的关键基因和视蛋白家族基因在大麻哈鱼的血管球囊中表达。免疫组织化学研究表明，所有这些基因都在血管球囊的冠状细胞中表达，这表明存在从光输入到神经内分泌输出的光周期信号通路。此外，分离的血管球囊有能力对光周期信号做出反应，并且其去除会消除性腺对光周期的反应。尽管血管球囊的生理作用已经是几个世纪的谜团，但我们的发现表明，血管球囊在鱼类中充当了日长季节性变化的传感器。
