胭脂鱼仔鱼的生长和消化酶活力变化

对胭脂鱼(Myxocyprinus asiaticus)孵化后1～37 d仔鱼的体长、体重、RNA/DNA比率、胰蛋白酶、脂肪酶和淀粉酶的酶活力变化进行了测定。结果显示:胭脂鱼仔鱼1～37 d体长稳定增长。体重增加呈阶段性,在1～21 d体重增长缓慢,21～29 d体重增加较快,29～37 d体重快速增加。仔鱼从7 d开始摄食,1～6 d,RNA/DNA比率变化很小,蛋白含量逐渐降低;7～21 d,RNA/DNA比率波动较大,蛋白含量增长缓慢;21～37 d,RNA/DNA比率和蛋白质均增长迅速。生长率(GR)与RNA/DNA比率的回归方程为:GR=1.01RNA/DNA+1.6077(R2=0.8516)。从2、5和7 d开始分别检测到明显的胰蛋白酶、脂肪酶和淀粉酶活力,之后,消化酶活力随着发育先快速地上升然后波动性地下降到一个稳定水平。结果表明:胭脂鱼仔鱼从内源性到外源性营养转化过程中,不同的消化酶能够检测到明显酶活力的时间不同,到仔鱼开始摄食时已经具备消化蛋白质、脂肪和淀粉的能力;RNA/DNA比率可以作为判定仔鱼生长率的可靠指标。

Variations of growth and digestive enzymes activities in the developmental Chinese sucker larvae(Myxocyprinus asiaticus Bleeker)

To better understand the development of Chinese sucker larvae,body length,body weight,RNA/DNA ratio,and the variations of trypsin,lipase and amylase enzymatic activities were measured during Chinese sucker larval development(1~37d).Results showed that the body length of Chinese sucker larvae were increased stably during 1~37 d.Weight gain displayed a step increases,it was slow during 1~21 d,fast during 21~29 d,and faster in 29~37 d.The larvae start initial feeding on the 7 d.RNA/DNA ratio changed a little bit and protein content decreased gradually during 1~6 d;RNA/DNA ratio and protein content increase slowly during 7~21 d;RNA/DNA ratio and protein content increased rapidly during 21~37 d.Linear regression equation of growth rate(GR) and RNA/DNA ratio is GR=1.01RNA/DNA+1.6077(R2=0.8516).The enzymatic activities of trypsin,lipase and amylase were detected obviously in 2,5 and 7 d respectively,then sharply rose and fluctuated down to a stable level at last.The results suggested that during the transition from endogenous nutrition to endogenous nutrition in Chinese sucker larvae,different digestive enzymatic activities initially appeared at different time.On the 7 d,larvae were able to digest the protein,lipid and starch in diet.RNA/DNA ratio was a reliable index to determine growth rate of Chinese sucker larvae.