渐变低温对不同规格菲律宾蛤仔斑马蛤酶活性的影响

摘要

斑马蛤是菲律宾蛤仔Ruditapes philippinarum的一个新品种,具有抗逆性强的特点,为探明其耐低温能力和机制,在实验室条件下模拟冬季低温环境,以8.2 ℃为对照,每3天降1 ℃,进行渐变低温 (5.4、2.2、0.2 ℃) 对3种规格 (壳长8、13、17 mm) 斑马蛤幼贝消化酶 (淀粉酶AMS、脂肪酶LPS和胃蛋白酶) 及抗氧化酶 (超氧化物歧化酶SOD和过氧化氢酶CAT) 酶活性的影响试验.结果表明:试验期间各组斑马蛤幼贝死亡率均小于3%;低温对淀粉酶呈诱导作用,并且对小规格幼贝 (壳长8 mm) 的诱导作用更明显,各温度下未检测到脂肪酶和胃蛋白酶;低温对SOD表现为诱导-抑制 (8 mm和13 mm蛤仔) 或诱导-抑制-诱导 (17 mm蛤仔) 的变化规律,总体上呈诱导作用,水温降至0.2 ℃时,随着规格的增大SOD酶活性升高;低温对CAT呈抑制作用 (17 mm蛤仔) 或抑制-诱导作用 (8 mm和13 mm蛤仔),总体呈抑制作用,且较小规格幼贝 (壳长8 mm, 5.4℃) 比较大规格 (壳长13 mm和17 mm, 2.2℃) 起始抑制的温度高,水温降至0.2 ℃时,随着规格的增大CAT酶活性下降;与CAT相比,幼贝以SOD为主来抵御低温带来的氧化损伤.本研究结果可为斑马蛤耐低温机制及中国北方大规模生产推广提供参考.%Digestive enzyme activities including amylase(AMS),lipase(LPS) and pepsin and antioxidant enzyme activities including superoxide dismutase (SOD) and catalase (CAT) were determined in Manila clam Ruditapes philippinarum with zebra-colored shell,as a new variety,with shell length of 8 mm,13 mm,and 17 mm in a labo-ratory at initial water temperature of 8.2℃ (as control) at a cooling rate of 1℃ per 3 days(5.4℃,2.2℃,and 0.2℃) in order to investigate the tolerance of Manila clam to low temperature and its mechanism in winter. The re-sults showed that there was no significant difference in mortality (less than 3%) among different groups. The AMS was shown to be induced by low temperature,especially in the juveniles with shell length of 8 mm,and lipase and pepsin activities were not detected. Under low temperatures,SOD activity was shown to show a first induction-then inhibition tendency in the juveniles with shell length of 8 mm and 13 mm and a tendency of first induction-then in-hibition-again induction in the juveniles with a shell length of 17 mm,wholly induction tendency.At water temper-ature of 0.2 ℃,the activity of SOD was increased with the increase in juvenile size. Low temperature led to inhibi-tory effect on CAT activity in juveniles with a shell length of 17 mm and induction-inhibition effect on juveniles with shell length of 8 and 13 mm. There was higher inhibition CAT activity temperature (5.4 ℃) in the juvenile with shell length of 8 mm than that(2.2℃) in the juvenile with shell length of 13 mm and 17 mm,with decrease in the CAT activity at 0.2 ℃ with the increase in the clam size. Compared with CAT,SOD was primarily response for resistance to oxidative damage in juvenile clam exposed to low temperatures. The findings will provide a refer-ence for understanding of the mechanism of low temperature tolerance and breeding.