Departamento de Fisiología (Fisiología Animal ), Facultad de Biología, Universidad Complutense de Madrid, Madrid, Spain.
J Biol Rhythms. 2011 Feb;26(1):24-33. doi: 10.1177/0748730410388600.
Little is known about the feeding time dependence of clock gene expression in fish. The aim of the present study was to investigate whether a scheduled feeding time can entrain the rhythmic expression of several clock genes (period and cryptocrome) in the brain and liver of a teleost, the goldfish. Fish maintained under continuous light (LL) conditions were divided into 3 groups. Two groups were fed daily at 1000 h and 2200 h, respectively, and the third group was subjected to a random schedule regime. After 30 days, the fishes under 24-h food deprivation were sacrificed through a 24-h cycle, and clock gene expression in the optic tectum, hypothalamus, and liver was quantified by real-time PCR. The findings pointed to differences between the central and peripheral tissues studied. In the absence of a light-dark cycle (constant light), a scheduled feeding regime was necessary and sufficient to maintain both the rhythmic expression of several clock genes in the optic tectum and hypothalamus, as well as daily rhythms in locomotor activity. In contrast, neither locomotor activity nor clock gene expression in brain tissues was synchronized in randomly fed fish. However, in the liver, most of the clock genes studied presented significant daily rhythms in phase (related to the time of the last meal) in all 3 experimental groups, suggesting that the daily rhythm of clock genes in this organ only depends on the last meal time. The data suggest that, as in mammals, the smooth running of the food entrainable oscillator (FEO) in fish involves the rhythmic expression of several clock genes (Per1 and Cry3) in the central and peripheral structures. The results also indicate that the food anticipatory activity (FAA) in goldfish is not only the result of rhythmic clock gene expression in the liver because rhythmic clock gene expression was observed in randomly fed fishes, while FAA was not observed.
关于鱼类时钟基因表达的摄食时间依赖性知之甚少。本研究旨在探讨定时摄食是否能使鱼类中枢和外周组织中几种时钟基因（周期和隐色素）的节律表达得到同步。将连续光照（LL）条件下的鱼分为 3 组，两组分别在 1000 h 和 2200 h 定时喂食，第三组则采用随机喂食方案。30 天后，对禁食 24 h 的鱼进行 24 h 周期的处死，并通过实时 PCR 定量检测视顶盖、下丘脑和肝脏中的时钟基因表达。研究结果表明，中枢和外周组织之间存在差异。在没有光-暗周期（持续光照）的情况下，定时喂食方案对于维持视顶盖和下丘脑的几种时钟基因的节律表达以及运动活动的昼夜节律是必要且充分的。相反，在随机喂食的鱼中，脑组织的运动活动和时钟基因表达均未同步。然而，在肝脏中，所研究的大多数时钟基因均表现出与最后一餐时间相关的相位（即每日节律），这表明该器官中时钟基因的每日节律仅取决于最后一餐的时间。这些数据表明，与哺乳动物一样，鱼类的食物可预测振荡器（FEO）的正常运转涉及中枢和外周结构中几种时钟基因（Per1 和 Cry3）的节律表达。研究结果还表明，金鱼的摄食前活动（FAA）不仅是肝脏中时钟基因节律表达的结果，因为在随机喂食的鱼中观察到了节律时钟基因表达，而 FAA 则没有观察到。
