Sarkar Olivia, Mukherjee Sunanda, Islam Shehnaz, Chattopadhyay Ansuman
Department of Zoology, Visva-Bharati, Santiniketan 731235, West Bengal, India.
Department of Zoology, Visva-Bharati, Santiniketan 731235, West Bengal, India.
Sci Total Environ. 2025 Sep 10;994:180053. doi: 10.1016/j.scitotenv.2025.180053. Epub 2025 Jul 10.
Lead (Pb) and chromium (Cr) are among the most extensively studied heavy metals due to their widespread presence and hazardous impacts on aquatic life. Pb and Cr exhibit strong genotoxic potential in aquatic environments by inducing DNA damage through overproduction of reactive oxygen species, resulting in oxidative stress, DNA strand breaks, and chromosomal aberrations. Disruption of nuclear integrity, impaired DNA repair pathways, and apoptosis activation further exacerbate their toxicity. However, most studies focus on their individual effects, often overlooking their combined genotoxic effects across multiple organs using a multi-endpoint approach under chronic, environmentally relevant exposure conditions. This study investigates the individual and combined genotoxic effects of Pb and Cr in adult male zebrafish (Danio rerio), a widely accepted ecotoxicological model, focusing on the blood, liver, gut, brain, and kidney as target tissues. Zebrafish were exposed to environmentally relevant concentrations of Pb (2.5, 5, and 10 ppb), Cr (0.5, 1, and 2 ppm), and their mixtures for 15, 30, and 60 days. Genotoxicity was assessed through erythrocytic nuclear anomalies assay, DNA fragmentation via agarose gel electrophoresis, apoptotic gene expression (p53, bax, bcl-2, caspase-9, and caspase-3) using qRT-PCR, and metal bioaccumulation by atomic absorption spectrophotometry. Results demonstrated a concentration- and time-dependent increase in nuclear anomalies, particularly micronuclei, blebbed, lobed, and notched nuclei, with the combined group showing the highest frequency. DNA fragmentation analysis confirmed significant genotoxicity, particularly in the liver and gut. Gene expression profiling revealed significant upregulation of pro-apoptotic genes (p53, bax, caspase-9, and caspase-3) and downregulation of bcl-2, indicating apoptosis induction. These findings underlined the synergistic and apoptotic effects of Pb and Cr, highlighting the importance of assessing chemical mixtures in aquatic toxicology. The study also offers mechanistic insights into tissue-specific toxicity, emphasizing the efficacy of zebrafish as a robust model for environmental risk assessment.
铅（Pb）和铬（Cr）是研究最为广泛的重金属，因为它们广泛存在且对水生生物有有害影响。铅和铬在水生环境中具有很强的遗传毒性潜力，通过活性氧的过量产生诱导DNA损伤，导致氧化应激、DNA链断裂和染色体畸变。核完整性的破坏、DNA修复途径的受损以及凋亡激活进一步加剧了它们的毒性。然而，大多数研究关注它们的单一效应，常常忽略在慢性、与环境相关的暴露条件下使用多终点方法对多个器官的联合遗传毒性效应。本研究调查了铅和铬对成年雄性斑马鱼（Danio rerio）的单一和联合遗传毒性效应，斑马鱼是一种广泛接受的生态毒理学模型，重点关注血液、肝脏、肠道、大脑和肾脏作为靶组织。将斑马鱼暴露于与环境相关浓度的铅（2.5、5和10 ppb）、铬（0.5、1和2 ppm）及其混合物中15、30和60天。通过红细胞核异常试验、琼脂糖凝胶电泳检测DNA片段化、使用qRT-PCR检测凋亡基因表达（p53、bax、bcl-2、caspase-9和caspase-3）以及原子吸收分光光度法检测金属生物积累来评估遗传毒性。结果表明核异常，特别是微核、泡状核、叶状核和缺口核呈浓度和时间依赖性增加，联合组的频率最高。DNA片段化分析证实了显著的遗传毒性，特别是在肝脏和肠道。基因表达谱显示促凋亡基因（p53、bax、caspase-9和caspase-3）显著上调，bcl-2下调，表明诱导了凋亡。这些发现强调了铅和铬的协同和凋亡效应，突出了在水生毒理学中评估化学混合物的重要性。该研究还提供了关于组织特异性毒性的机制见解，强调了斑马鱼作为环境风险评估有力模型的有效性。
