Laboratorio de Calidad de Agua y Acuicultura Experimental, Centro Universitario de la Costa, Universidad de Guadalajara, Puerto Vallarta, Jalisco, México.
Doctoral program in BEMARENA, Universidad de Guadalajara, Puerto Vallarta, Jalisco, México.
Fish Physiol Biochem. 2024 Dec;50(6):2535-2550. doi: 10.1007/s10695-024-01400-y. Epub 2024 Sep 16.
The Pacific fat sleeper, Dormitator latifrons, is an omnivorous freshwater fish that primarily feeds on detritus. Our understanding of the digestive physiology of this species still needs to be completed, particularly concerning the characterization of its digestive enzymes. This information is crucial in guiding the design of diets that promote optimal digestion of this species, which has the potential for aquaculture. Thus, this study aimed to optimize enzymatic methods and characterize the digestive enzymes of the digestive tract regions: anterior region (AR), middle region (MR), posterior region (PR), and hepatopancreas (HP). Total acid protease, total alkaline protease, amylase, and lipase activities were measured. The enzymatic methods were optimized at an eco-physiological temperature of 25 °C based on extract volume, extract dilution, incubation time, pH, and CaCl concentration to determine specific activity (U/mg of protein). The optimal pH for acid protease (AR) was pH 2.0; while for alkaline protease, the optimal pH was between 7.5 and 11.0. For AR, chymotrypsin was pH 7.0; for the remaining digestive regions, it was pH 9.0-11.0. The optimal pH for amylase was 6.0 to 7.5 (all regions), and for lipase, it was between 7.0 and 11.0, with two apparent in vitro activity peaks (PR). HP experimental samples showed low or no chymotrypsin, amylase, and lipase activity. CaCl did not affect enzyme activity except for amylase and lipase (only in PR and HP, respectively). The acid proteolytic activity (pH 2.0) found in AR and the proteolytic inhibition by pepstatin suggest the presence of a stomach.
太平洋肥脂睡鲨，Dormitator latifrons，是一种杂食性淡水鱼，主要以碎屑为食。我们对该物种消化生理学的了解仍有待完善，特别是其消化酶的特征。这些信息对于指导设计促进该物种最佳消化的饮食至关重要，因为该物种具有水产养殖的潜力。因此，本研究旨在优化酶法并表征消化道区域的消化酶：前区（AR）、中区（MR）、后区（PR）和肝胰腺（HP）。测量了总酸性蛋白酶、总碱性蛋白酶、淀粉酶和脂肪酶的活性。根据提取体积、提取稀释度、孵育时间、pH 和 CaCl 浓度，在生态生理温度 25°C 下优化了酶法，以确定比活度（U/mg 蛋白）。酸性蛋白酶（AR）的最佳 pH 值为 2.0；而碱性蛋白酶的最佳 pH 值在 7.5 和 11.0 之间。对于 AR，糜蛋白酶的最适 pH 值为 7.0；对于其余消化区，最适 pH 值为 9.0-11.0。淀粉酶的最佳 pH 值为 6.0 至 7.5（所有区域），脂肪酶的最佳 pH 值在 7.0 和 11.0 之间，在 PR 和 HP 中分别有两个体外活性峰。HP 实验样品显示出低或无糜蛋白酶、淀粉酶和脂肪酶活性。除了淀粉酶和脂肪酶（仅在 PR 和 HP 中）外，CaCl 不影响酶活性。在 AR 中发现的酸性蛋白水解活性（pH 2.0）和胃蛋白酶抑制剂对蛋白水解的抑制作用表明存在胃。
