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A study of putative brain circadiom oscillators in amphibians and fish

两栖动物和鱼类假定的大脑昼夜节律振荡器的研究

基本信息

批准号：
11640686
负责人：
CHIBA Atsuhiko
金额：
$ 2.3万
依托单位：
Sophia University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

1. To obtain the insight on the molecular mechanisms of the circadian clock in amphibians and fish, we isolated partial cDNAs encoding Per2 from the Japanese newt (Cynops pyrrhogaster) and Per2, Per3, Clock and Bmall from the ayu (Plecoglossus altivels).2. Plasma melatonin levels in the newt, ayu and rainbow trout (Oncorhynchus mykiss) determined by radioimmuno-assay exhibited significant daily variation under light-dark cycles. In the newt, the day-night change in plasma melatonin level was abolished by either pinealectomy or bilateral ocular enucleation. Plasma melatonin levels exhibit circadian variation under constant darkness in the ayu but not in the rainbow trout.3. We characterized and localized melatonin receptors in the newt brain. The melatonin receptors are highly specific for melatonin with picomolar affinity. Autoradiographic studies revealed uneven distribution in the brain with the highest density observed in the optic tectum.4. By using the number of synaptic ribbon in … More the pineal photoreceptor as a phase marker of the pineal circadian clock, we showed that daily melatonin injections entrained the pineal circadian clock as well as circadian locomotor activity rhythm in the newt.5. We covered the newt's skull with aluminum foil and simultaneously reversed the light-dark cycle. Locomotor activity rhythm of the head-covered animals was entrained to the reversed light-dark cycle while the rhythm of pineal synaptic ribbon number remained almost the same phase as the original one. These data suggest that under light-dark cycle retinally perceived light can entrain the circadian clock in the brain without help from the pineal circadian clock.6. The effects of pinealectomy on circadian rhythms in the demand-feeding activity of the rainbow trout were examined. Pinealectomy affected the demand-feeding activity under neither light-dark nor constant light conditions, indicating that the pineal organ is not essential to maintain the function of the circadian clock in the brain. Less

1. 为了深入了解两栖动物和鱼类生物钟的分子机制，我们从日本蝾螈（Cynopspyrrhogaster）中分离出了编码Per2的部分cDNA，从香鱼（Plecoglossus altivels）中分离出了编码Per2、Per3、Clock和Bmall的部分cDNA。2．通过放射免疫测定法测定的蝾螈、香鱼和虹鳟鱼（Oncorhynchus mykiss）的血浆褪黑激素水平在光暗循环下表现出显着的每日变化。在蝾螈中，血浆褪黑激素水平的昼夜变化可以通过松果体切除术或双侧眼剜除术消除。香鱼的血浆褪黑素水平在持续黑暗的情况下表现出昼夜节律变化，但虹鳟鱼则不然。3。我们对蝾螈大脑中的褪黑激素受体进行了表征和定位。褪黑激素受体对褪黑激素具有高度特异性，具有皮摩尔亲和力。放射自显影研究显示大脑中分布不均匀，在视顶盖中观察到密度最高。4．通过使用松果体光感受器中突触带的数量作为松果体生物钟的相位标记，我们发现每天注射褪黑激素会影响松果体生物钟以及蝾螈的昼夜运动活动节律。5。我们用铝箔覆盖蝾螈的头骨，同时颠倒明暗循环。蒙头动物的运动活动节律被引入相反的明暗周期，而松果体突触带数量的节律与原始节律几乎保持相同的相位。这些数据表明，在明暗循环下，视网膜感知的光可以在没有松果体生物钟帮助的情况下将生物钟带入大脑。6。研究了松果体切除术对虹鳟鱼按需摄食活动昼夜节律的影响。松果体切除术既不影响明暗条件下的需求喂养活动，也不影响恒定光照条件下的需求喂养活动，这表明松果体器官对于维持大脑中生物钟的功能并不是必需的。较少的