黄条仔稚幼鱼消化酶活性变化研究

The Variations of Digestive Enzymes in Larval and Juvenile Seriola aureovittata

为了解黄条(Seriola aureovittata)早期发育阶段的消化生理特性,测定了黄条胚胎、仔稚幼鱼阶段脂肪酶、淀粉酶、胰蛋白酶和碱性磷酸酶活性变化。结果显示,在黄条仔鱼出膜前胚胎阶段,即能检测到脂肪酶、淀粉酶和碱性磷酸酶活性;初孵仔鱼体内(1 d)初次检测出胰蛋白酶的活性。脂肪酶和碱性磷酸酶比活力在仔鱼孵化后迅速增强(P<0.05),在4 d开口时,2种酶比活力达最高值;淀粉酶比活力在7 d时达最大值;胰蛋白酶比活力在仔鱼阶段缓慢上升,15 d时比活力最大。稚鱼阶段内脏团中脂肪酶、碱性磷酸酶和胰蛋白酶活性基本维持稳定,幼鱼阶段内脏团脂肪酶、碱性磷酸酶和胰蛋白酶活性都呈现上升趋势;稚鱼和幼鱼阶段内脏团中淀粉酶活性下降并基本稳定于较低水平。研究表明,黄条仔稚幼鱼发育过程中,各种消化酶活性变化明显,且与其发育阶段和食性密切相关。在尚未摄食饵料的早期仔鱼体内已存在消化酶,认为其是母源传递而来,不是由外源性饵料所致;幼鱼阶段内脏团脂肪酶、碱性磷酸酶和胰蛋白酶比活力明显提高,这反映出随苗种生长发育,其肠道结构和消化机能逐渐完善,并且对脂肪、蛋白质的需求逐渐增强。

To clarify the digestive and physiological characteristics in the early developmental stage of Seriola aureovittata,the activity of different digestive enzymes(lipase,amylase,trypsin,and alkaline phosphatase)were studied.Fertilized eggs and 1-to 60-day-old larvae and juveniles of S.aureovittata were selected as the research objects.The relationship between total length and days after hatching was also studied.The results indicated that the total length of larvae and juveniles increased with age within 60 days after hatching and increased significantly after 25 days.Lipase,amylase,and alkaline phosphatase were detectable during the embryonic stage while trypsin was detected in newly hatched larvae,which indicated that S.aureovittata can digest lipid,carbohydrate,and proteins before feeding.The specific activities of lipase and alkaline phosphatase increased rapidly after hatching(P<0.05),reached a peak at(5.88±0.45)and(5.56±0.41)U/mg,respectively at first feeding.The amylase activity reached its peak at(1.59±0.02)U/mg on day 7.The specific activity of trypsin increased slowly after hatching,and reached the highest value((1098.67±24.03)U/mg on day 15(P<0.05).Lipase,alkaline phosphatase,and trypsin were basically stable in the visceral mass of juvenile fish.However,the activity of lipase,alkaline phosphatase,and trypsin increased with the development of S.aureovittata.The amylase activity in the visceral mass of juvenile fish showed a downward trend and was basically stable at a lower specific activity level.The results of this study showed significant changes in various digestive enzyme activities during the development of larvae and juveniles,which were closely related to the development stage and feeding habits.The digestive enzymes were detected in early larvae that had not yet eaten food which was considered that the digestive enzymes were maternal in origin and not from exogenous food.The lipase,alkaline phosphatase,and trypsin activities in juveniles significantly increased,which reflect the improvement of intestinal structure and digestive function and the increasing demand for fat and protein.