Localization of circadian clock and its structure

昼夜节律是一种由时间测量机制(生物钟)支撑的大约-24小时的内源性振荡。阐明这一机制的策略包括三个进展阶段：(1)候选时钟组织的定位，(2)组织自振荡能力的证明，(3)从细胞或分子生物学的角度探讨更深层次的机制。该项目团队由12名积极参与这一战略的研究人员组成。时钟在后生动物中的定位：板球视叶的自振荡能力也得到了确凿的证明。对啮齿动物进行了视交叉上核种间移植。对脊椎动物松果体和眼睛中控制显性节律的关键因素--褪黑素产生的研究进一步深入。细胞水平的时钟：一项分子生物学研究阐明，脉孢子虫节律的时钟突变的特征是钙代谢异常。利用计算机监测细胞运动的系统，分析草履虫游动节律的生物物理机制。对甲状旁腺激素细胞进行免疫组织化学定位，发现甲状旁腺激素细胞可能是昆虫大脑时钟的重要组成部分。光周期时钟：光周期如何与昼夜节律相关也进行了研究。在一项板球研究中，得到了一个有趣的结果，即重水延长了运动的自由运行周期，但不影响临界光周期。现在被广泛接受的外部符合模型可能不适用于这种情况。基因克隆技术：这项新发展的技术在昆虫的大脑和前胸钟以及鸟类松果钟的研究中得到了重视。

Circadian rhythm is an about-24 hr endogenous oscillation underlain by a time measuring mechanism (circadian clock). A strategy for elucidating the mechanism includes three progressive stages: (1) localization of candidate clock tissues, (2) demonstrat-tion of a self-oscillating ability of the tissue, and (3) approaches to deeper mechanisms from aspects of cell or molecular biology. This project team comprised 12 active researchers working along this strategy.Results were obtained as follows.1. Localization of the clock in Metazoa: Self-oscillating ability of the cricket optic lobe were demonstrated alomst conclusively. Interspecies transplantation of the suprachiasmatic nuclei were attempted with rodents. Studies on melatonin production , a key factor for controlling overt rhythms, in the pineal body and the eye of vertebrates were deepened.2. Clocks at cellular level: A molecular-biological study clarified that a clock mutant of a Neurospora rhythm is characterized by an abnormal calcium metabolism. Biophysical mechanisms of Paramecium swimming rhythm were analysed using a computerized system for monitoring cell movements. PTTH cells, which may form an essential part of the insect brain clock, were tried to be located by an immunohistochemical method.3. Photoperiodic clocks: How photoperiodism is related to circadian rhythm was also studied. An interesting result was obtained, in a cricket study,that heavy water lengthened the freerunning period of locomotion but did not affect the critical photoperiod. External coincidence model now widely accepted may not apply to this case.4. Gene cloning techniques: Utility of this newly developed techniques was emphasized in studies on brain and prothoracic clock of insects and bird pineal clock.