低温休眠预处理对花鲈无水保活效果的影响

花鲈(Lateolabrax maculatus)由养殖水温22～23℃分别经1、3℃/h和5℃/h不同降温速率处理至临界温度4℃,无水活运8 h,通过检测花鲈肝组织的半胱氨酸蛋白酶-3(Caspase-3)活力、丙二醛(malonaldehyde,MDA)浓度及血清中鱼前蛋白转化酶枯草溶菌素-9(protein convertase subtilisin kexin type 9,PCSK-9)、谷丙转氨酶(alanine aminotransferase,ALT)、谷草转氨酶(aspartate aminotransferase,AST)活力,研究不同降温速率休眠处理后无水活运对花鲈肝组织损伤的影响,获得最佳降温速率处理条件,降低运输过程中鱼体损伤,提高存活率,以期获得最优的花鲈无水活运技术。结果表明:运输0 h,3个降温速率处理组花鲈肝组织Caspase-3活力、MDA浓度及血清中PCSK-9、AST、ALT活力较对照组均增高;在模拟运输8 h时,3℃/h降温处理组花鲈上述5个指标均显著低于1、5℃/h降温处理组(P0.05),且显著高于对照组;运输2 h后,3℃/h降温处理组花鲈血清中PCSK-9活力显著低于1、5℃/h降温处理组(P0.05);与运输8 h比较,唤醒后花鲈的肝组织内MDA浓度、Caspase-3活力呈下降趋势,但依然很高,PCSK-9活力增高,AST活力增长减缓或降低,表明不同降温速率条件下无水活运过程对花鲈肝脏的损伤不能在短时间内恢复。因此,花鲈可以通过低温诱导休眠的方式进行无水保活,3℃/h组处理后无水活运8 h对花鲈肝组织损害程度低,存活率高,建议将降温速率设定为3℃/h。

Effect of Precooling Treatment on Survival of Lateolabrax maculatus during Live Transportation without Using Water

Lateolabrax maculatus reared at 22–23 ℃ were acclimated at a cooling rate of 1, 3 or 5 ℃/h to the critical temperature 4 ℃ before live transportation for 8 h without using water. In order to establish the optimal cooling rate for reducing liver damage and increasing the survival rate during the transportation of fish, the effect of cold acclimation on liver damage in Lateolabrax maculatus was evaluated by detecting caspase-3 activity and malondialdehyde (MDA) content in liver and proprotein convertase subtilisin kexin type 9 (PCSK-9), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity in serum. The results showed that at 0 h of transportation all investigated biochemical parameters in three treatment groups were higher than in the control group. At 8 h of transportation, these five parameters were significantly lower in the 3 ℃/h cooling group than in two other treatment groups but higher than in the control group (P < 0.05). At 2 h, serum PCSK-9 activity was significantly lower in the 3 ℃/h cooling group than in the other treatment groups (P < 0.05). Liver MDA concentration and caspase-3 activity in Chinese sea bass after arousal were decreased compared to those at 8 h but were still high. In addition, serum PCSK-9 activity was increased and AST activity was increased more slowly or declined, indicating that the liver damage caused by precooling treatment could not be recovered in a short time during live transportation without using water. Therefore, Lateolabrax maculatus can be kept alive by low temperature-induced hibernation, and sea bass acclimated at 3 ℃/h cooling rate suffered less liver damage and showed a higher survival rate at 8 h of transportation. In conclusion, a cooling rate of 3 ℃/h is recommended for Lateolabrax maculatus to transported alive without using water.