本期Nature Communications上發(fā)表的一項研究報告說，魚的一個名為“血管囊”（saccus vasculosus）的器官起體內時鐘的作用,，檢測白天長短的季節(jié)差別,。
在哺乳動物中,，陽光是由眼睛捕捉的，信息被傳遞到腦垂體的結節(jié)部,，后者將季節(jié)信息再傳給大腦,。這個腺體起一個季節(jié)時鐘的作用，讓大腦知道當前是白天還是夜晚,，并將短的天與長的天區(qū)分開來,，從而能夠對不同季節(jié)進行分辨,。由于魚沒有結節(jié)部，所以一直不清楚它們是否有一個能夠充當季節(jié)傳感器作用的器官,。
Takashi Yosimura及其同事在用“馬蘇三文魚”所做的一項研究中,，通過檢測“血管囊”對光周期信號（如白天長度的變化）的反應能力演示了該器官的時鐘功能。他們觀察了調控季節(jié)性繁殖的已知基因的表達以及與那些在眼睛中或松果腺中所發(fā)現(xiàn)的光受體相似的已知的光受體,。他們還發(fā)現(xiàn),，孤立的“血管囊”會對光的變化做出反應，而且沒有“血管囊”的魚會失去它們對光的變化做出反應的能力,。（生物谷Bioon.com）
生物谷推薦英文摘要：
Nature Communications doi:10.1038/ncomms3108
The saccus vasculosus of fish is a sensor of seasonal changes in day length
Yusuke Nakane, Keisuke Ikegami, Masayuki Iigo, Hiroko Ono, Korenori Takeda, Daisuke Takahashi, Maiko Uesaka, Meita Kimijima, Ramu Hashimoto, Natsumi Arai, Takuya Suga, Katsuya Kosuge, Tomotaka Abe, Ryosuke Maeda, Takumi Senga, Noriko Amiya, Teruo Azuma, Masafumi Amano, Hideki Abe, Naoyuki Yamamoto et al.
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.
