Holthues Heike, Engel Lydia, Spessert Rainer, Vollrath Lutz
Department of Anatomy, Johannes Gutenberg University, 55099 Mainz, Germany.
Biochem Biophys Res Commun. 2005 Jan 7;326(1):160-5. doi: 10.1016/j.bbrc.2004.11.022.
The directly light-sensitive chick pineal gland contains at least two photopigments. Pinopsin seems to mediate the acute inhibitory effect of light on melatonin synthesis, whereas melanopsin may act by phase-shifting the intrapineal circadian clock. In the present study we have investigated, by means of quantitative RT-PCR, the daily rhythm of photopigment gene expression as monitored by mRNA levels. Under a 12-h light/12-h dark cycle, the mRNA levels of both pigments were 5-fold higher in the transitional phase from light to dark than at night, both in vivo and in vitro. Under constant darkness in vivo and in vitro, the peak of pinopsin mRNA levels was attenuated, whereas that of melanopsin was not. Thus, whereas the daily rhythm of pinopsin gene expression is dually regulated by light plus the intrapineal circadian oscillator, that of melanopsin appears to depend solely on the oscillator.
直接对光敏感的鸡松果体至少含有两种光色素。视蛋白似乎介导了光对褪黑素合成的急性抑制作用，而黑视蛋白可能通过使松果体内的生物钟相位移动来发挥作用。在本研究中，我们通过定量逆转录聚合酶链反应，以mRNA水平监测光色素基因表达的昼夜节律。在12小时光照/12小时黑暗周期下，无论是在体内还是体外，两种色素的mRNA水平在从光到暗的过渡阶段都比夜间高5倍。在体内和体外持续黑暗条件下，视蛋白mRNA水平的峰值减弱，而黑视蛋白的峰值未减弱。因此，视蛋白基因表达的昼夜节律受光和松果体内生物钟振荡器的双重调节，而黑视蛋白的昼夜节律似乎仅取决于生物钟振荡器。
