ABSTRACT

Effects of different regimes of photoperiod (12L–12D, 16L–8D, 8L–16D, LL and DD) were studied on the circadian rhythm of expression of core clock genes (clock, bmal1, per1, per2, per3, cry1 and cry2) in the photosensitive pineal organ of air-breathing catfish, Clarias gariepinus during summer and winter seasons under both in vivo and in vitro conditions using qPCR. Our findings indicate that all major core clock genes are expressed in the photosensitive pineal organ of C. gariepinus, and exhibit significant circadian rhythm of their expression under both in vivo and in vitro conditions irrespective of photoperiods and seasons. However, photoperiods had season-dependent differential effects on mesor (24 h average), amplitude, and acrophase (peak) of the circadian rhythm of expression of the clock genes under both in vivo and in vitro conditions. Based on these findings, we suggest that the photosensitive pineal organ of the fish possesses internal autonomous clockwork composed of clock genes, and different photoperiods deferentially affect rhythm parameters of the rhythmic expression of the pineal clock genes in a season-dependent manner.

摘要

研究了不同光周期方案（12L-12D、16L-8D、8L-16D、LL 和 DD）对核心时钟基因（clock、bmal1、per1、per2、per3、cry1和cry2）表达昼夜节律的影响在使用 qPCR的体内和体外条件下，在夏季和冬季期间，在呼吸鲶鱼的光敏松果体中，Clarias gariepinus 。我们的研究结果表明，所有主要的核心时钟基因都在C. gariepinus的光敏松果体器官中表达，并且在体内和体外均表现出显着的昼夜节律。不受光周期和季节的影响。然而，光周期对体内和体外条件下时钟基因表达的昼夜节律的中值（24 小时平均值）、幅度和顶相（峰值）具有季节依赖性差异影响。基于这些发现，我们认为鱼的光敏松果体器官具有由时钟基因组成的内部自主发条，不同的光周期以季节依赖性方式依次影响松果体时钟基因节律表达的节律参数。