密度胁迫对大口黑鲈游泳行为及肌肉能量代谢的影响

Effects of density stress on swimming behavior and muscle energy metabolism of Micropterus salmoides

过高的养殖密度会导致鱼类生长受到抑制,为探明大口黑鲈(Micropterus salmoides)应对密度胁迫的行为生理响应,设置了低(90尾·m^(-3))、中(110尾·m^(-3))、高(130尾·m^(-3))3个密度梯度,研究了大口黑鲈在胁迫1周后的游泳行为及红、白肌肉能量代谢相关酶的基因表达和活性变化。结果表明:大口黑鲈游泳频率、摆尾频率和游泳速度均随密度呈显著升高趋势(P<0.05)。密度对大口黑鲈红肌己糖激酶(HK)、磷酸果糖激酶(PFK)和乳酸脱氢酶(LDH)等无氧代谢酶的基因表达和活性无显著性影响(P>0.05)。密度由低水平升至中水平时,大口黑鲈红肌丙酮酸脱氢酶(PDH)、柠檬酸合酶(CS)和苹果酸脱氢酶(MDH)等有氧代谢酶的基因相对表达量显著上调且酶活性显著上升(P<0.05),密度由低水平升至高水平时,大口黑鲈红肌PDH、CS和MDH等有氧代谢酶以及白肌HK、PFK和LDH等无氧代谢酶的基因相对表达量显著上调且酶活性显著上升(P<0.05)。研究表明,密度通过改变大口黑鲈游泳行为来影响肌肉能量代谢,中密度主要依靠红肌有氧代谢供能,高密度则主要依靠红肌有氧代谢和白肌无氧代谢来参与能量供应。

Excessive aquaculture density may inhibit fish growth.To investigate the behavioral and physiological responses of largemouth bass(Micropterus salmoides)to density stress,we conducted an experiment with three densities[Low(90 individuals·m^(-3)),medium(110 individuals·m^(-3))and high(130 individuals·m^(-3))].Then we determined the swimming behavior,enzyme activity and gene relative expression of energy metabolism in red and white muscles of M.salmoides after one week of density stress.The results show that the swimming frequency,tail-beat frequency and swimming speeds increased with density(P<0.05).Density did not significantly affect the gene expression and activities of anaerobic metabolic enzymes such as hexokinase(HK),phosphofructokinase(PFK)and lactate dehydrogenase(LDH)in red muscles(P>0.05).When the density increased from low to medium level,the gene relative expression of aerobic metabolism enzymes such as pyruvate dehydrogenase(PDH),citrate synthase(CS)and malate dehydrogenase(MDH)in red muscles increased significantly(P<0.05),so did the activities of these enzymes(P<0.05).When the density increased from low to high level,the gene relative expression levels of aerobic metabolism enzymes such as PDH,CS and MDH in red muscles,as well as anaerobic metabolism enzymes such as HK,PFK and LDH in white muscles increased significantly(P<0.05),so did the activities of these enzymes(P<0.05).It is indicated that density affects the energy metabolism of muscles by altering the swimming behavior of M.salmoides.Medium density mainly relies on aerobic metabolism of the red muscle for energy supply,while high density mainly relies on aerobic metabolism of the red muscle and anaerobic metabolism of the white muscle to participate in energy supply.