Lead is a metal capable of affecting physiology and metabolism in fish, including Nile tilapia (Oreochromis niloticus). However, few studies have evaluated the effects of lead on digestive enzyme activities in fry. At that stage, independent feeding begins, and there is increased demand and consumption of food, so chronic exposure to metal during this stage of development would cause null or minimal growth in organisms. In this study, fry from Nile tilapia was used to evaluate the effects of lead acetate by chronic exposure on the growth and the activities of the digestive enzymes after 30 and 60 days exposures. Four treatment groups 0.025, 0.050, 0.075 and 0.100 mg/L of lead acetate and a lead-free control were established. The activity of enzymes decreased, in the case of acidic proteases after 30 days and lipases after 60 days of exposure, from 0.025 and 0.050 mg/L of lead acetate, respectively. The amylase activity increased in metal-treated, while the chymotrypsin decreased partially at 60 days. Lipases decreasing activity might be causing an increase of triglycerides (lipids) and body mass observed during the first 30 days of exposure. Concentrations, equal to or above 0.075 mg Pb/L, cause significant effects on size and weight of fry, with nearly 54% lower than controls. At chronic exposure and early stage of development, the enzymatic activity is partially reduced along with body weight gain, which would affect subsequent growing and aquaculture production. The digestive enzyme response is discussed as a possible limited biomarker of exposure, to be used in biomonitoring.

中文翻译：

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铅暴露对尼罗罗非鱼生长和消化酶活性的影响。

铅是一种能够影响鱼类生理和代谢的金属，包括尼罗罗非鱼（Oreochromis niloticus）。但是，很少有研究评估铅对鱼苗消化酶活性的影响。在那个阶段，开始独立喂养，并且食物的需求和消耗都在增加，因此在发育的这一阶段长期接触金属会导致生物体的无效生长或最小生长。在这项研究中，尼罗罗非鱼的鱼苗被用来评估乙酸铅对慢性暴露对30和60天暴露后生长和消化酶活性的影响。建立了四个处理组，分别为0.025、0.050、0.075和0.100 mg / L乙酸铅和无铅对照。在暴露30天后为酸性蛋白酶和暴露60天后为脂肪酶的情况下，酶的活性分别从0.025和0.050 mg / L乙酸铅降低。金属处理后，淀粉酶活性增加，而胰凝乳蛋白酶在60天时部分下降。脂肪酶活性下降可能会导致在暴露的前30天内观察到的甘油三酸酯（脂质）和体重增加。浓度等于或高于0.075 mg Pb / L会对鱼苗的大小和重量产生显着影响，比对照组低近54％。在长期接触和发育的早期阶段，酶活性随体重增加而部分降低，这将影响随后的生长和水产养殖产量。消化酶反应被讨论为可能的有限暴露生物标志物，将用于生物监测。等于或高于0.075 mg Pb / L，会对鱼苗的大小和重量产生重大影响，比对照组低近54％。在长期接触和发育的早期阶段，酶活性随体重增加而部分降低，这将影响随后的生长和水产养殖产量。消化酶反应被讨论为可能的有限暴露生物标志物，将用于生物监测。等于或高于0.075 mg Pb / L，会对鱼苗的大小和重量产生重大影响，比对照组低近54％。在长期接触和发育的早期阶段，酶活性随体重增加而部分降低，这将影响随后的生长和水产养殖产量。消化酶反应被讨论为可能的有限暴露生物标志物，将用于生物监测。