大菱鲆仔稚鱼期消化酶及碱性磷酸酶活性的变化

Development of Some Digestive Enzymes and Alkaline Phosphatase Activities in Turbot Scophthalmus maximus Larvae and Juveniles

针对海水鱼类仔稚鱼期高死亡率的现状,本实验采集不同发育阶段的大菱鲆,分析测定了酸、碱性蛋白酶、淀粉酶和脂肪酶以及消化道碱性磷酸酶的活性变化,以期为提高大菱鲆仔稚鱼期的成活率和生长率以及优化饵料配方提供理论依据。结果表明,大菱鲆初孵仔鱼体内就已具有碱性蛋白酶活性,而酸性蛋白酶活性在15日龄左右胃腺出现时才测得。蛋白酶活性的3个极低值分别出现于仔鱼开口期,卵黄囊完全消失期和仔鱼向稚鱼的转变期。早期仔鱼体内表现出较强的淀粉酶活性,5日龄时其活性急剧下降,并一直保持较低的比活力水平。脂肪酶活性在仔稚鱼期一直很弱,进入幼鱼期后比活力迅速升高。碱性磷酸酶活性从初孵到5 0日龄左右始终保持较小幅度的上升,直到60日龄变态完成时才出现大幅度的升高。大菱鲆仔稚鱼发育过程中,消化道中各种酶活性变化显著,仔稚鱼变态完成后,蛋白酶、脂肪酶和碱性磷酸酶活性显著增强,这标志着大菱鲆由稚鱼期向幼鱼期的转变及消化机能的完善。

In order to provide a further theoretic basis for improving the survival rate, growth rate and optimizing the diet, the activities of some digestive enzymes and alkaline phosphatase were investigated during the larval and juvenile development of the turbot. The alkaline protease activity was identified after hatching. Acid protease was not present until the appearance of the gastric gland (about 15 days old). Three extremely low protease activities were observed during the period of the first feeding, the complete absorption of yolk sac and the transition from larva to juvenile. The noticeable amylase activity was present during the early stage of larvae and decreased significantly after they were 5 days old; from then on, it always remained at a low relative activity. The activity of lipase was very low before entering the young stage. The activity of alkaline phosphatase increased slowly from day 1 to day 50 but thereafter it showed a sharp increase. Important variations in specific activities of all the enzymes were observed during the period of development. At the end of metamorphosis, the activities of protease, lipase and alkaline phosphatase increased significantly, indicating the transition from juvenile to young and the improvement of the digestive system of turbot.