School of Ecology and Environmental Sciences, Yunnan University, Kunming 650091, PR China; Department of Fisheries, University of Dhaka, Dhaka 1000, Bangladesh.
Department of Fisheries, University of Dhaka, Dhaka 1000, Bangladesh.
Comp Biochem Physiol C Toxicol Pharmacol. 2024 Feb;276:109800. doi: 10.1016/j.cbpc.2023.109800. Epub 2023 Nov 20.
Waterborne cadmium (Cd) accumulates in the fish intestine and causes irreversible toxicity by disrupting intestinal immunity and microbial diversity. To explore the toxicity of environmentally available high Cd concentration on intestinal immunity and microbial diversity of fish, we selected the widely used bioindicator model species, Common carp (Cyprinus carpio). Literature review and Cd pollution data supported sequential doses of 0.2, 0.4, 0.8, 1.6, 3.2, and 6.4 mg/L Cd for 30 days. Based on intestinal tissue Cd accumulation, previous studies, and environmentally available Cd data, 0.4 and 1.6 mg/L Cd were selected for further studies. Intestinal Cd bioaccumulation increased significantly to ~100 times in fish exposed to 1.6 mg/L Cd. We observed villous atrophy, increased goblet cells with mucus production, muscularis erosion, and thickened lamina propria due to intense inflammatory cell infiltration in the intestine at this Cd concentration. Cd-induced immunosuppression occurred with increased lysozyme, alkaline phosphate (AKP), and acid phosphate (ACP). High levels of catalase (CAT), total antioxidant capacity (T-AOC), malondialdehyde (MDA), and hydrogen peroxide (HO) suggested induced oxidative stress and poor metabolism by α-amylase and lipase suppression for Cd toxicity. Proteobacteria (41.2 %), Firmicutes (21.8 %), and Bacteroidetes (17.5 %) were the dominant bacterial phyla in the common carp intestine. Additionally, potential pathogenic Cyanobacteria increased in Cd-treated fish. The decrease of beneficiary bacteria like Aeromonas, and Cetobacterium indicated Cd toxicity. Overall, these findings indicate harmful consequences of high Cd concentration in the intestinal homeostasis and health status of fish.
水中的镉（Cd）在鱼类肠道中积累，并通过破坏肠道免疫和微生物多样性而导致不可逆转的毒性。为了探索环境中高浓度 Cd 对鱼类肠道免疫和微生物多样性的毒性，我们选择了广泛使用的生物指示剂模型物种——鲤鱼（Cyprinus carpio）。文献综述和 Cd 污染数据支持以 0.2、0.4、0.8、1.6、3.2 和 6.4 mg/L Cd 的顺序剂量进行 30 天的实验。基于肠道组织中的 Cd 积累、先前的研究以及环境中可利用的 Cd 数据，选择了 0.4 和 1.6 mg/L Cd 进行进一步研究。在暴露于 1.6 mg/L Cd 的鱼类中，肠道 Cd 生物积累显著增加了约 100 倍。在该 Cd 浓度下，我们观察到肠道绒毛萎缩、杯状细胞增多伴有黏液分泌、肌层侵蚀和固有层增厚，这是由于强烈的炎症细胞浸润所致。Cd 诱导的免疫抑制表现为溶菌酶、碱性磷酸酶（AKP）和酸性磷酸酶（ACP）的增加。过氧化氢酶（CAT）、总抗氧化能力（T-AOC）、丙二醛（MDA）和过氧化氢（HO）的高水平表明，α-淀粉酶和脂肪酶的抑制导致了氧化应激和代谢不良。在鲤鱼肠道中，优势细菌门为变形菌门（41.2%）、厚壁菌门（21.8%）和拟杆菌门（17.5%）。此外，在 Cd 处理的鱼类中，潜在的致病性蓝藻增加。有益细菌如气单胞菌和产甲烷菌的减少表明 Cd 具有毒性。总的来说，这些发现表明高浓度 Cd 对鱼类肠道内稳态和健康状况具有有害影响。
