College of Life and Environmental Sciences, Hunan University of Arts and Science, Changde, Hunan 415000, China; Hunan Provincial Key Laboratory for Health Aquaculture and Product Processing in Dongting Lake Area, Changde, Hunan 415000, China; Hunan Provincial Key Laboratory for Molecular Immunity Technology of Aquatic Animal Diseases, Changde, Hunan 415000, China.
College of Life and Environmental Sciences, Hunan University of Arts and Science, Changde, Hunan 415000, China.
Ecotoxicol Environ Saf. 2022 Sep 1;242:113895. doi: 10.1016/j.ecoenv.2022.113895. Epub 2022 Jul 21.
Red swamp crayfish (Procambarus clarkii) has increasingly become a high-value freshwater product in China. During the intensive cultivation, excessive ammonia exposure is an important lethal factor of crayfish. We investigated the toxic effects and mechanisms of ammonia on crayfish at two different developmental stages. A preliminary ammonia stress test showed a 96-h LC of 135.10 mg/L and 299.61 mg/L for Stage_1 crayfish (8.47 ± 1.68 g) and Stage_2 crayfish (18.33 ± 2.41 g), respectively. During a prolonged ammonia exposure (up to 96 h), serum acid phosphatase and alkaline phosphatase showed a time-dependent decrease. Histological assessment indicated the degree of hepatopancreatic injury, which was mainly characterized as tubule lumen dilatation, degenerated tubule, vacuolization and dissolved hepatic epithelial cell, increased with exposure time. Enhanced malondialdehyde level and reduced antioxidant capacity of hepatopancreas were also observed. The mRNA expression and activity of catalase and superoxide dismutase showed an initial up-regulation within 24 h, and then gradually down-regulated with the exposure time. In the post-treatment recovery period, the Stage_2 crayfish exerted a stronger antioxidant and detoxification capacity than that of the Stage_1 crayfish, and thus quickly recovered from the ammonia exposure. Our findings provide a further understanding of the adverse effects of ammonia stress and suggest guidelines for water quality management during crayfish farming.
红螯螯虾（Procambarus clarkii）在中国已逐渐成为一种高价值的淡水产品。在集约化养殖过程中，过高的氨暴露是虾类的一个重要致死因素。我们研究了氨对两个不同发育阶段的螯虾的毒性作用和机制。初步的氨胁迫试验表明，阶段 1 的螯虾（8.47±1.68 g）和阶段 2 的螯虾（18.33±2.41 g）的 96 h 半数致死浓度（LC）分别为 135.10 mg/L 和 299.61 mg/L。在长时间的氨暴露（长达 96 h）中，血清酸性磷酸酶和碱性磷酸酶表现出时间依赖性下降。组织学评估表明，肝胰腺损伤的程度主要表现为管腔扩张、退化的小管、空泡化和溶解的肝上皮细胞，随着暴露时间的增加而增加。还观察到丙二醛水平升高和肝胰腺抗氧化能力降低。过氧化氢酶和超氧化物歧化酶的 mRNA 表达和活性在 24 h 内表现出初始上调，然后随着暴露时间的延长逐渐下调。在治疗后的恢复期，阶段 2 的螯虾比阶段 1 的螯虾表现出更强的抗氧化和解毒能力，因此能够更快地从氨暴露中恢复。我们的研究结果进一步了解了氨胁迫的不良影响，并为虾类养殖中的水质管理提供了指导。
