冷胁迫方式对太平洋牡蛎无水保活期氧化应激及能量消耗的影响

Effect of Cold Stress Methods on Antioxidant and Energy Metabolism of Crassostrea gigas in Water-free Live Storage Period

【目的】系统分析太平洋牡蛎(Crassostrea gigas)保活运输前的预冷方式及温度胁迫对其氧化免疫系统、能量物质代谢的影响,筛选出较好的无水保活前预冷方式。【方法】分别采用散冰自然降温、急性连续降温、线性匀速降温、梯度降温4种低温诱导休眠方式处理牡蛎,并探讨不同诱导休眠方式对牡蛎生态冰温无水保活期的存活率、失重率、抗氧化能力以及能量物质代谢的影响。【结果】1)梯度和线性降温牡蛎冰温保活9 d其存活率及失重率优于散冰和急性降温组。2)各组牡蛎在整个保活期内抗氧化酶活力均升高,且散冰降温组显著高于急性、线性和梯度降温组(P<0.05);散冰和急性降温组丙二醛(MDA)含量呈明显上升趋势,而线性和梯度降温组先降后升高;各不同降温组过氧化氢(H_(2)O_(2))含量则先升后降;总抗氧化能力(T-AOC)随胁迫时间延长呈上升趋势。3)散冰降温组在整个保活期内能量物质均显著低于各组(P<0.05),保活9 d后线性和梯度降温组水分、糖原、脂肪含量高于各组,乳酸含量则低于各组。【结论】采用线性和梯度降温方式诱导牡蛎进入生态冰温休眠状态后开始无水保活,有利于减缓牡蛎在冷胁迫下抗氧化酶活力及脂质过氧化的影响,且保活时间更长,失重率更低,能量代谢物质损失较少,更有利于牡蛎长时间无水保活。

【Objective】To systematically analyze the effects of pre-cooling and temperature stress on the oxidative immune system and energy metabolism of Crassostrea gigas before live transport,and select a better pre-cooling methods before waterless keep alive.【Method】Oysters were either treated by natural cooling,acute continuous cooling,linear uniform cooling and gradient cooling in crush ice.The survival rate,weight loss rate,antioxidant capacity,energy metabolism of the oyster were determined to evaluate the best method of dormancy induction.【Results】1)the survival rate and weight loss rate of gradient and linear cooling methods were better than the natural cooling and acute cooling.2)The antioxidant enzyme activity of each group increased during the whole live storage,ice cooling group was significantly higher than acute,linear and gradient cooling groups(P<0.05);MDA content in natural cooling and acute cooling group were increased significantly.In contrast,the MDA value showed an initial decreased then increased trend in the linear and gradient cooling groups;each groups.The H_(2)O_(2) level of all test groups showed an initial increased and then decreased pattern while the T-AOC was at an upward trend when the stress time was extended.3)The energy content of ice cooling group was significantly lower than other groups during the test period(P<0.05).The moisture,glycogen and fat content of the linear and gradient cooling groups were higher than the others groups,but lactic acid was lower than them.【Conclusion】When the C.gigas under ice are induced dormancy and are kept waterless after treatment by linear and gradient cooling methods(cooling rate≤5℃/h),the antioxidant enzyme activity and lipid peroxidation will be reduced.The survival time is extended,the weight loss rate and the loss of energy metabolites is lower for the cold stress group,which is more conductive to the waterless keep alive retention of oysters.