The study of biological clock responsible for suprachiasmatic nucleus-independent circadian rhythm induced by restricted feeding

1.LD（光-暗）周期相移与摄食时间的影响（野生型小鼠（WT）与Cry 1&2双突变、行为节律不调小鼠（DKO）的比较）LD周期相移后，WT经过几个短暂周期后重新进入新的LD周期，而DKO在新的LD周期的黑暗期立即进入活跃阶段。在持续黑暗（DD）条件下，WT和DKO均表现出对限制摄食的预期活动节律，尽管在WT条件下，它们的动态图中也观察到视交叉上核（SCN）依赖的自由奔跑成分。在对摄食时间进行相移后，WT和DKO均在几天内建立了响应新摄食时间的活动节律。然而，在前一种喂养时间建立的节奏在两种类型的小鼠中也保持了几个周期。这表明限制性摄食诱导节律的产生和携带机制的分子基础与依赖于scn的昼夜节律至少部分不同。在短周期小鼠（SP）中，WT和SP的动态图显示，无论给定的限制性摄食节律的时间长短，DD中都存在scn依赖的自由奔跑成分。WT （N=6）和SP （N=8）小鼠均在26h ~ 34h的限定摄食期，但有一半的SP小鼠在34h摄食期未表现出明显的摄食诱导节律。这可能说明限制摄食诱导的SP节律的可携带上限往往比WT短。自由摄食条件下，所有WT和SP小鼠的LD周期在26 ~ 31 h之间。SP小鼠的LD周期上限是否比WT小鼠的LD周期上限更短，还有待于采用更长的LD周期进行进一步研究。然而，SP小鼠scn依赖性活动节律的携带机制可能与WT至少部分不同，因为在本研究中，SP小鼠随着LD周期的延长，活动期有提前的趋势。少

1.Effects of phase-shift of LD(light-dark) cycle and feeding time (Comparison between Wild-type mice(WT) and Cry 1&2 double mutant, behaviorally arrhythmic mice (DKO))After phase-shift of LD cycle, WT reentrained to the new LD cycle after several transient cycles while DKO immediately showed active phase during the dark period of the new LD cycle. In constant darkness (DD), both WT and DKO showed the anticipatory activity rhythm in response to restricted feeding, although in WT, suprachiasmatic nucleus(SCN)-dependent free-running component was also observed in their actograms. After phase-shift of the feeding time, the activity rhythm in response to the new feeding time was established within a couple of days in both WT and DKO. The rhythm which had established by the former feeding time, however, was also maintained for several cycles in both types of mice. This suggests that the molecular basis of the mechanisms for generation and entrainment of restricted feeding-induced rhythm is a … More t least in part different from that of SCN-dependent circadian rhythm.2.The entrainable range of SCN-dependent rhythm and restricted feeding-induced rhythm (WT vs.Cry1 mutant, short-period mice (SP))The actogram from both WT and SP showed SCN-dependent free-running component in DD irrespective of the period of given restricted feeding rhythms. Restricted feeding period ranging from 26h to 34h entrained all WT (N=6) and SP (N=8) mice except the fact that a half of SP mice failed to show clear feeding-induced rhythm when they were subjected to the 34 h feeding rhythm. This may suggest that upper entrainable limit of restricted feeding-induced rhythm of SP tends to be shorter than that of WT. LD cycles with the periods ranging from 26 h to 31 h under free access to food entrained all WT and SP mice. Further study using LD cycles with longer period is required to examine if upper entrainable limit of the period of LD cycle is shorter in SP mice than that in WT mice. Entraining mechanism of SCN-dependent activity rhythm of SP mouse, however, may be at least in part different from that in WT because, in the present study, the activity phase tended to be advanced as the period of LD cycle increases in SP mice. Less