温度及光照驯化对南方鲇线粒体代谢补偿调节的影响

摘要

为了检验在季节驯化中温度和光周期分别对南方鲇(Silurus meridionalis Chen)组织线粒体代谢补偿效应的调节作用,研究对实验鱼进行了4个系列的驯化处理：(1)低温等光周期[12.5℃,12L︰12D,体重：(186.36±2.77) g]；(2)高温等光周期[27.5℃,12L︰12D,体重：(202.80±7.99) g]；(3)短光照中等温[8L︰16D,20℃,体重：(284.80±13.47) g]；(4)长光照中等温度[16L︰8D,20℃,体重：(283.70±15.60) g],每组均为24尾鱼。驯化8周后取样,测定了各驯化组鱼体心脏、肝脏和肾脏的器官质量(器官指数),以及这3种器官组织线粒体在测定温度为12.5℃、20℃和27.5℃时的呼吸率和细胞色素C氧化酶(CCO)活性。结果显示,在等光周期条件下,低温驯化组(12.5℃,12L︰12D)实验鱼的心脏、肝脏和肾脏的器官指数均显著高于高温驯化组(27.5℃,12L︰12D)；在中等温度条件下不同光照处理的实验鱼之间器官指数无显著差异。在中等温度条件下短光照驯化组(8L︰16D,20℃)鱼体的心脏、肾脏和肝脏组织线粒体呼吸率和CCO活性均显著高于长光照组(16L︰8D,20℃)；而在等光周期条件下的不同温度驯化并没引起这3种组织线粒体的呼吸率和CCO活性的明显差异。综合认为：在季节驯化过程中,光周期改变是引起线粒体代谢能力的主要因素,温度变化则是调整器官组织重量的主要因素,光周期与温度对南方鲇线粒体代谢机制的调整具有协同作用。%To evaluate the effects of ambient temperature and day-length respectively in setting metabolic com-pensation of mitochondria in juvenile of the southern catfish (Silurus meridionalis Chen), the organ index of the heart, kidney and liver and their state 3 rates of mitochondria and cytochrome C oxidase activity (CCO) were measured in the tested fishes at different acclimations. Two experimental groups were acclimated to high tem-perature (27.5℃) and low temperature (12.5℃) at equivalent photoperiod (12L︰12D), and other two groups were kept at long day-length (16L︰8D) and short day-length (8L︰16D) condition at same moderate temperature (20℃). There were 24 individuals in each group. Fish were maintained at these acclimation conditions for 8 weeks before sampling. In condition of the equivalent photoperiod, the organ index of the heart, kidney, and liver in the cold-acclimatized group (12.5℃, 12L︰12D) were all significantly higher than that in the warm group (12L︰12D, 27.5℃) (P<0.05). The acclimation of day-length did not cause any change in organ mass at same moderate tem-perature. At assay temperature of 12.5, 20, and 27.5℃, both state 3 rates of mitochondria and activity of CCO in the heart, kidney, and liver in the short day-length group (8L︰16D, 20℃) were significantly higher than those in long day-length group (16L︰8D, 20℃). State 3 rates of mitochondria and activity of CCO in the three tissues were not influenced by thermal acclimation. The results showed that day-length initiates changes in the mitochon-drial oxidative capacity and the temperature was the major ambient factor to alter the organ mass. It is suggested that during seasonal acclimatization photoperiod signal and thermal condition might have a cooperative effect on the adjustment for metabolic compensation in the southern catfish.