低温胁迫对云纹石斑鱼(♀)×鞍带石斑鱼(♂)杂交后代血清生化指标的影响

选取云纹石斑鱼(Epinephelus moara♀)×鞍带石斑鱼(E.lanceolatus♂)的杂交种(俗称云龙石斑鱼)为研究对象,设定20℃、16℃、15℃、13℃和10℃共5个温度梯度(20℃为对照组),从20℃开始,采取1℃/d的降温速率,对其进行低温胁迫实验,并对云龙石斑鱼血清中生化指标和代谢酶活力进行检测.同时对棕点石斑鱼(E fuscoguttatus♀)和鞍带石斑鱼(♂)的杂交种(俗称珍珠龙胆石斑鱼)、斜带石斑鱼(E.coioides♀)×鞍带石斑鱼(♂)的杂交种(俗称青龙石斑鱼)进行低温胁迫,每天记录3种杂交石斑鱼的存活率.当存活率低于50％时,记录半致死温度.结果显示,云龙石斑鱼半致死温度为8℃,珍珠龙胆石斑鱼的半致死温度为11℃,青龙石斑鱼的半致死温度为9.5℃.云龙石斑鱼血清中肌酐(CREA)含量和总胆固醇(T-CHO)含量随低温胁迫强度增加呈先降低后上升的趋势,血清甘油三酯(TG)含量呈现波动,在15℃和10℃时与对照组比较,出现显著性差异(P＜0.05).血清葡萄糖(GLU)含量随胁迫强度的增加呈现波动,在16℃和13℃时与对照组之间有显著性差异(P＜0.05).碱性磷酸酶(AKP)活性在16℃时有所升高,但整体上与对照组无显著性差异(P＞0.05).过氧化氢酶(CAT)活性呈现波动,除13℃以外,其余各组均与对照组有显著性差异(P＜0.05).血清中谷草转氨酶(GOT)的活性在13℃和16℃时略高于对照组.谷丙转氨酶(GPT)活性呈现先升后降的趋势,在16℃和15℃时,与对照组差异显著(P＜0.05).结果表明,3种杂交石斑鱼中,云龙石斑鱼最耐受低温;低温胁迫会导致幼鱼免疫力和抗氧化能力下降,实际生产中仍应降低胁迫强度和缩短胁迫时间.

Effects of Low Temperature Stress on Serum Biochemical Indices of the Juvenile Hybrid of Epinephelus moara♀ × Epinephelus lanceolatus♂

Low temperature tolerance of Epinephelus moara♀ × E.lanceolatus♂(hereinafier Yunlong) was investigated in this study.The initial water temperature (20℃) was served as control,and then was dropped at a rate of 1 ℃/d,the changes in serum biochemical indices and metabolic enzyme activities of Yunlong were determined when the water temperatures reached 16℃,15℃,13℃ and 10℃.During the cold stress period,survival rates and the semi-lethal temperatures of Yunlong,E.fuscoguttatus♀× E.lanceolatus♂ (Pearl Gentian),and E.coioides♀ × Eo lanceolatus♂(Qinglong) were observed and recorded.The semi-lethal temperature was recorded when the survival rate reached 50％.We found that the semi-lethal temperatures for Pearl Gentian,Qinglong and Yunlong were ll℃,9.5℃,9℃,and 8℃ respectively.The levels of serum creatinine (CREA) and total cholesterol (T-CHO) were first increased and then decreased along with increase of the intensity and duration of the low temperature stress.The level of serum triglycerides (TG) fluctuated at different temperatures,and the values at 15℃ and 10℃C were significantly different from that of the control group (P＜0.05).The content of serum glucose (GLU) also varied with the temperatures,the levels at 16℃ and 13℃ were different from that of the control group (P＜0.05).The activity of serum alkaline phosphatase (AKP) at 16℃ was slightly and insignificantly increased (P＞0.05).The activity of serum catalase (CAT) fluctuated and showed significant differences between the control group and low temperatures at 16℃,15℃ and 10℃ (P＜0.05).The activity of serum glutamic-oxaloacetic transaminase (GOT) was slightly higher than that of the control group (P＞0.05).The activity of serum glutamate pyruvate transaminase (GPT) was elevated followed by a decline along with the increase in the intensity and duration of low temperature stress.At 16℃ and 15℃,the activity of GPT was different from that of the control group (P＜0.05).In conclusion,Yunlong was the most tolerant to low temperature stress among the three hybrids.Our data also suggested that low temperature could impair the immunity and the antioxidant capacity of juvenile fish,therefore the intensity and duration of the low temperature condition should be limited during practice.