饥饿和温度驯化对中华倒刺鲃静止代谢和游泳能力的影响

The effects of fasting andacclimation temperature on the resting metabolism and swimming performance in qingbo( Spinibarbus sinensis)

为了探讨饥饿和温度驯化对中华倒刺鲃(Spinibarbus sinensis)幼鱼维持代谢和游泳运动能力的影响,在不同温度(15、25℃)条件下分别测定了经0(对照)、1、2、4周饥饿后中华倒刺钯的静止代谢率(M_(O_2_(rest))和匀加速最大游泳速度(U_(CAT))。饥饿和低温对M_(o_2_(rest))和U_(CAT)均有负效应。在高温条件下,实验鱼经1周饥饿后其M_(o_2_(rest))和U_(CAT)均显著下降(P<0.05);但在低温条件下,仅4周饥饿组的M_(o_2_(rest))和U_(CAT)显著下降(P<0.05)。U_(CAT)与M_(o_2_(rest))在不同的饥饿周期具有相似的变化趋势;在低温条件下,前期饥饿阶段M_(o_2_(rest))和U_(CAT)变化较小,后期饥饿阶段变化较大;但在高温条件下则相反。无论是在低温还是在高温条件下,U_(CAT)与M_(o_2_(rest))之间均呈显著线性正相关(P<0.05),但低温组回归方程斜率显著高于高温组回归方程斜率(F_(1,4)=11.416,P=0.028)。在不同温度下,中华倒刺钯游泳运动能力对饥饿的反应不尽相同可能与维持代谢、生化反应速率、机体能量储存、代谢酶活性及底物利用类型等的差异相关,这种对策的差异可能是其对栖息地环境温度和食物资源季节性变化的适应。

Long and/or short periods of fasting are common for aquatic species,because of the temporal and spatial patchiness of food availability that is a consequence of environmental and seasonal changes.It is generally accepted that in the temperate zone,the food supply for fish displays strong seasonal oscillations due to seasonal temperature fluctuations.Fish species must face two exogenous stresses in the winter：low temperatures and insufficient food resources.The aim of this study was to test whether fasting affects the maintenance metabolism and swimming performance of fish and whether the possible effects varied with acclimation temperature.To achieve our goal,we measured the resting metabolic rate（M（o2（rest）））and constant acceleration test speed（U（CAT）） of juvenile qingbo（Spirinbarbus sinensis） after 0（control）,1,2,and 4 weeks of fasting at both low and high acclimation temperatures（15 and 25 ℃）.Both fasting treatment and temperature acclimation had significant effects on M（O2（rest）） and U（CAT）（P0.05）.At the higher temperature,fasting had a negative effect on M（O2（rest）） and U（CAT） after 1 week（P0.05）.However,when acclimated to the lower temperature,fasting had a negative effect on M（o2rest）and U（CAT） until up to week 4（P0.05）.The values of the M（o2rest）and U（CAT） in the lower temperature treatment were significantly lower than those in the higher temperature treatment,in groups experiencing identical fasting periods（P〈0.05）.The relationship between M（O2（rest）） and fasting time（t） was described as M（o2（rest（15））=-1.96t^2-5.39t＋117.02（R^2 = 161,P0.001,n=24） and M（o2（rest（25））=11.36t^2-76.59t＋246.55（R^2=0.505,P0.001,n=24） at 15 and 25 ℃.respectively.Both U（CAT） and M（o2（rest）） showed similar decreases in response to fasting,in either the lower or higher temperature treatments.The relationship between U（CAT） and fasting time（t） was described as U（CAT）（15））=-0.91t^2＋0.89t＋54.16（R^2=0.343,P0.001,n= 32） and U（CAT（25））=1.18t^2-8.48t＋74.14（R^2=0.532,P0.001,n=32） at 15 and 25℃.respectively.A positive correlation between U（CAT） and M（o2（rest）） was found in both the low and high temperature treatments.The relationship between U（CAT） and M（o2（rest）） was described as U（CAT（15））=0.23 M（o2（rest））＋28.99（R^2 =0.961,P=0.020,n=4） and U（CAT（25）） = 0.12 M（o2（rest））＋45.59（R=0.980,P=0.010,n=4） at 15 and 25℃,respectively.The slope value of the regression equation in the low temperature treatment was significantly greater than that in the high temperature treatment（F（1,4）=11.416,P = 0.028）.Swimming performance decreased less in the early stage of fasting,but decreased more in the later fasting stage in the low temperature treatment than in the high temperature treatment.This might be related to differences in resting metabolism,biochemical reaction rates,energy stores,enzyme activity in muscle tissue,and energy substrate utilization between fish subjected to low or high acclimation temperatures.The divergent responses of swimming performance to fasting in qingbo at different acclimation temperatures might be an adaptive strategy to seasonal temperature and food resource variations.