匙吻鲟仔稚鱼消化酶发育的研究

DIGESTIVE ENZYME ACTIVITY DURING EARLY LARVAL DEVELOPMENT OF THE PADDLEFISH POLYODON SPATHULA

对出膜后0—53d匙吻鲟的酸性蛋白酶、碱性蛋白酶、α-淀粉酶、脂肪酶以及磷酸酶的活性变化进行了测定。匙吻鲟出膜后饲养于室内水泥培育池中,从第3天开始投喂枝角类,之后于第40天将试验鱼转移至池塘。试验材料为受精卵及出膜后第3、第6、第12、第20、第30、第40、第44、第47、第53天仔稚鱼样品。研究发现主要消化酶在出膜时或卵黄期即可检测出活力。碱性蛋白酶和酸性蛋白酶分别在出膜后3d(3DAH)和刚出膜时(0DAH)检测出活力。碱性蛋白酶活力在44DAH达到最大值[(1.96±0.09)U/fish],47DAH出现下降,但在53DAH开始上升,比活力在53DAH达到最大值[(8.84±0.59)U/mg protein]。酸性蛋白酶在44DAH达到最大值[(0.52±0.05)U/fish],比活力在6DAH出现第一个峰值[(2.08±0.09)U/mg protein],并在30DAH出现最小值[(0.83±0.06)U/mg protein]。试验期间碱性蛋白酶活力高于酸性蛋白酶。在12DAH—40DAH期间α-淀粉酶活力相对稳定,并在47DAH达到最大值[(0.42±0.03)U/fish],比活力在12DAH出现一个峰值[(1.18±0.12)U/mg protein],并于47DAH出现最大值[(1.94±0.16)U/mg protein]。发育早期脂肪酶活力较高,活力和比活力分别在30DAH[(0.20±0.02)U/fish]和6DAH[(2.28±0.22)U/mg protein]出现最大值。碱性磷酸酶活力变化趋势与比活力变化趋势相似,但是最大值分别出现在44DAH[(0.08±0.00)U/fish]和30DAH[(1.96±0.15)U/mg protein]。酸性磷酸酶活力在3DAH出现一个峰值[(0.01±0.00)U/fish],之后显著升高,并在44DAH达到最大值[(0.05±0.00)U/fish],其比活分别在30DAH[(1.19±0.10)U/mg protein]和44DAH[(1.10±0.08)U/mg protein]出现两个峰值。结果表明,蛋白酶、α-淀粉酶和磷酸酶随个体发育活力增加,碱性蛋白酶在个体发育早期对蛋白质的消化具有重要作用。养殖环境发生改变时,酸性蛋白酶、α-淀粉酶、碱性磷酸酶和酸性磷酸酶活力在生长减慢时增加,生长加快时降低,而脂肪酶活力则维持稳定。

The ontogenesis of digestive enzymes （proteases, a-amylases, lipases and phosphatases） in paddlefish Polyodon spathula w±as determined in larvae between 0-53 days after hatching （DAH）. From initiation of exogenous feeding （3 DAH）, larvae were fed Cladocera for 37 days in indoor cement pit, and then transferred to pond fed natural food. Fertilized eggs and larval fish samples day 3, 6, 12, 20, 30, 40, 44, 47 and 53 after hatching were taken as the test materials. The results showed that most of the digestive enzymes activities could be detected before the onset of the exogenous feeding. Alkaline protease activity was detected at 3 DAH and acid protease activity was quantifiable from eggs. Alkaline protease activity reached to the maximum level at 44 DAH [（1.96±0.09） U/fish], followed by a decrease and then an increase on 47 DAH. The specific alkaline protease activity reached to the peak level at 53 DAH [（8.844±0.59） U/mg protein]. Acid protease had its maximum activity at 44 DAH [（0.524±0.05） U/fish], its specific activ- ity reached the first peak on 6 DAH [（2.084±0.09） U/mg protein], followed by the minimum on 30 DAH [（0.834±0.06） U/mg protein]. Alkaline protease activity was consistently higher than acid protease activity, a-Amylases activity was relatively stable during incubation period in workshop （12 DAH-40 DAH） and reached to the maximum on 47 DAH [（0.424-±0.03） U/fish]. Two peaks were found about the specific a-amylase activity, a small one on 12 DAH [（1.184±0.12） U/mg protein] and the maximum peak on 47 DAH [（1.944±0.16） U/mg protein]. Both lipase activity and specific lipase activity had one peak on 30 DAH [（0.204±0.02） U/fish] and 6 DAH [（2.284±0.22） U/mg protein] respectively. High lipase activity implied the importance of lipid utilization. The alkaline phosphatase activity and the specific phosphatase activ- ity showed similar trends, with the exception of the maximum period, 44 DAH [（0.084±0.00） U/fish] and 30 DAH [（1.964±0.15） U/mg protein] respectively. Acid phosphatase activity had one peak on 3 DAH [（0.014±0.00） U/fish], fol- lowed by a significant increase and reached maximum on 44 DAH [（0.054±0.00） U/fish]. Two main peaks were detected about the specific of acid phosphatase activity, one on 30 DAH [（1.194±0.10） U/mg protein] and the other on 44 DAH [（1.104±0.08） U/mg protein]. It suggested that protease, a-amylase and phosphatase activities increased with the onto- genesis of paddlefish, and alkaline protease was important to paddlefish larval. Acid protease, a-amylase, acid and alka- line phosphatase activities increased with growth decreasing and decreased with growth increasing when fish transferred to pond.