Abstract

The aim of this study is to investigate the genotoxic effects of mixtures of five metals on zebrafish at two different concentrations; at the permissible maximum contamination levels in drinking water and irrigation waters. The drinking water limits are as follows: 300 µg/L for Aluminum (Al⁺³), 10 µg/L for Arsenic (As⁺³), 5 µg/L for Cadmium (Cd⁺²), 10 µg/L for Cobalt (Co⁺²), and 50 µg/L for Chromium (Cr⁺²). The irrigation water limits: 5000 µg/L for Al⁺³, 100 µg/L for As⁺³, 10 µg/L for Cd⁺², 50 µg/L for Co⁺², and 100 µg/L for Cr⁺². The zebrafish underwent chronic exposure for periods of 5, 10, and 20 days. The gene expressions for mitochondrial superoxide dismutase (SOD2), stress-specific receptor protein NCCRP1, the heat shock proteins: Hsp9, Hsp14, Hsp60, Hsp70, DNA repair (XRCC1 and EXO1), and apoptosis (BOK and BAX) were evaluated. It was found that exposure to the low- and high-concentrations of the heavy metal mixtures caused cell stress, an increased expression of the antioxidant genes, and repair proteins. As the duration of exposure was increased, the cells progressed through the apoptotic pathway. This was more evident in the high-concentration exposure groups. The results demonstrated the necessity for a reevaluation of the maximum values of heavy metal and toxic element concentrations as prescribed by the Local Standing Rules of Water Pollution Control Regulation, as well as a reevaluation of the limitations of heavy metal mixture interactions with respect to ecological balance and environmental health.

• Highlights

• The purpose of this study was to investigate the genotoxic effects of a mixture of Aluminum, Arsenic, Cadmium, Cobalt, Chromium on zebrafish, within drinking water, and irrigation water limits determining the concentration.

• The zebrafish were exposed to two different concentrations of each metal mixture for 5-, 10-, and 20-day periods. Following exposure, gene expressions of the zebrafish’s gill tissues were examined.

• As a result of the exposure to the metal mixtures, the following occurred: cell stress, increased antioxidant gene activity, and attempts to protect cell viability. However, the cells progressed through the apoptotic pathway after prolonged exposure.

• The results demonstrated the necessity for a reevaluation of the maximum limits of metal and toxic element concentrations as stated in the Standing Rules of Water Pollution Control Regulation.

摘要

本研究的目的是研究两种不同浓度的五种金属混合物对斑马鱼的遗传毒性影响；饮用水和灌溉用水中允许的最大污染水平。饮用水限值如下：铝 (Al ⁺³ ) 300 µg/L，砷 (As ⁺³ ) 10 µg/L，镉 (Cd ⁺² ) 5 µg/L，钴 10 µg/L (Co ⁺² )，铬 (Cr ⁺² ) 为 50 µg/L。灌溉用水限值：Al ⁺³为 5000 µg/L ，As ⁺³为 100 µg/ L，Cd ⁺²为 10 µg/ L，Co ⁺²为 50 µg/ L，Cr ^{+2为 100 µg/L}. 斑马鱼经历了 5、10 和 20 天的慢性暴露。评估了线粒体超氧化物歧化酶 (SOD2)、应激特异性受体蛋白 NCCRP1、热休克蛋白：Hsp9、Hsp14、Hsp60、Hsp70、DNA 修复（XRCC1 和 EXO1）和细胞凋亡（BOK 和 BAX）的基因表达。研究发现，暴露于低浓度和高浓度的重金属混合物会导致细胞应激、抗氧化基因表达增加和修复蛋白。随着暴露时间的增加，细胞通过凋亡途径进行。这在高浓度暴露组中更为明显。

• 强调

• 本研究的目的是研究铝、砷、镉、钴、铬的混合物对斑马鱼、饮用水和灌溉水限制浓度的遗传毒性影响。

• 斑马鱼暴露在两种不同浓度的每种金属混合物中 5 天、10 天和 20 天。暴露后，检查了斑马鱼鳃组织的基因表达。

• 由于暴露于金属混合物，发生了以下情况：细胞应激、抗氧化基因活性增加以及保护细胞活力的尝试。然而，长时间暴露后，细胞通过凋亡途径进行。

• 结果表明有必要重新评估《水污染控制条例常设规则》中规定的金属和有毒元素浓度的最大限值。