Dai Caijiao, Xiao Lin, Mo Aijie, Yuan Yongchao, Yuan Junfa, Gu Zemao, Wang Jianghua
College of Fisheries, Huazhong Agricultural University, Wuhan, 430070, China.
Hubei Engineering Technology Research Center for Aquatic Animal Disease Control and Prevention, Wuhan, 430070, China.
Environ Sci Pollut Res Int. 2023 Mar;30(15):43914-43926. doi: 10.1007/s11356-023-25297-x. Epub 2023 Jan 21.
Cadmium (Cd), a non-biodegradable contaminant in freshwater ecosystems, can pose a serious threat to aquatic animals at high levels. In this study, the Cd toxicokinetics and the immune and antioxidant defense were explored in Procambarus clarkii exposed to different levels of Cd (0, 0.1, 1.0 mg Cd/L) or treated with 1.0 mg Cd/L and dietary Bacillus subtilis supplementation (1 × 10 cfu/g). Results from the 21-day uptake and depuration experiment revealed that Cd exposure elicited a dose- and time-dependent uptake in all crayfish tissues, and the rank order of Cd concentration was gill > hepatopancreas > exoskeleton > muscle. The one-compartment model demonstrated that gills had the highest uptake rate (k) value after Cd aqueous exposure and the k and elimination rate (k) values in gill, hepatopancreas, and exoskeleton of the group with 1.0 mg Cd/L were higher than those of the group at alow Cd concentration (0.1 mg Cd/L). However, B. subtilis could decrease Cd k and increase Cd k in hepatopancreas, resulting in the reduction of bioconcentration factors (BCF), steady-state concentrations (C), and biological half-life (T). A positive correlation was found between aqueous Cd concentration and the severity of hepatopancreas histopathological injury, while B. subtilis could ameliorate the pathological damage in the high Cd group. Similarly, aqueous exposure to Cd elevated malonaldehyde (MDA) content and suppressed the activities of lysozyme (LZM), acid phosphatase (ACP) in hepatopancreas and alkaline phosphatase (AKP) in hemolymph. The activities of superoxide dismutase (SOD) and catalase (CAT) in hepatopancreas were also inhibited. Nevertheless, they were all recovered with the dietary addition of B. subtilis. In conclusion, our results indicated that exposure to Cd significantly increased Cd accumulation and toxic damages in crayfish hepatopancreas, while dietary administration of B. subtilis to crayfish significantly decreased Cd accumulation and improved the immune and antioxidant defense, leading to the prevention in toxic effects of Cd.
镉（Cd）是淡水生态系统中一种不可生物降解的污染物，高浓度时会对水生动物构成严重威胁。在本研究中，探究了克氏原螯虾在暴露于不同浓度Cd（0、0.1、1.0 mg Cd/L）或用1.0 mg Cd/L处理并添加饲料芽孢杆菌（1×10 cfu/g）时的Cd毒代动力学以及免疫和抗氧化防御情况。为期21天的吸收和净化实验结果显示，Cd暴露在所有小龙虾组织中引发了剂量和时间依赖性吸收，Cd浓度排序为鳃＞肝胰腺＞外骨骼＞肌肉。单室模型表明，Cd水溶液暴露后鳃的吸收速率（k）值最高，且1.0 mg Cd/L组鳃、肝胰腺和外骨骼中的k值及消除速率（k）值高于低Cd浓度（0.1 mg Cd/L）组。然而，芽孢杆菌可降低肝胰腺中Cd的k值并增加其k值，从而导致生物富集系数（BCF）、稳态浓度（C）和生物半衰期（T）降低。发现水体Cd浓度与肝胰腺组织病理学损伤严重程度呈正相关，而芽孢杆菌可改善高Cd组的病理损伤。同样，水体暴露于Cd会提高丙二醛（MDA）含量，并抑制肝胰腺中溶菌酶（LZM）、酸性磷酸酶（ACP）以及血淋巴中碱性磷酸酶（AKP）的活性。肝胰腺中超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的活性也受到抑制。不过，饲料中添加芽孢杆菌后这些指标均恢复正常。总之，我们的结果表明，暴露于Cd会显著增加小龙虾肝胰腺中Cd的积累和毒性损伤，而给小龙虾投喂芽孢杆菌可显著降低Cd积累并改善免疫和抗氧化防御，从而预防Cd的毒性作用。
