Department of Biology, Institute of Science, Giresun University, Giresun, Turkey.
Faculty of Science and Art, Department of Biology, Giresun University, Giresun, Turkey.
Environ Sci Pollut Res Int. 2024 Sep;31(44):56140-56152. doi: 10.1007/s11356-024-34940-0. Epub 2024 Sep 11.
In this study, the toxicity of the trace element zinc (Zn) in Allium cepa L. test material was examined. Toxicity was investigated in terms of physiological, cytogenetic, biochemical, and anatomical aspects. Germination percentage, root length, weight gain, mitotic index (MI), micronucleus (MN) frequency, chromosomal abnormalities (CAs), malondialdehyde (MDA), proline and chlorophyll levels, superoxide dismutase (SOD) and catalase (CAT) enzyme activities, and meristematic cell damage were used as indicators of toxicity. Additionally, the comet test was used to measure the degree of DNA damage. Four groups of A. cepa bulbs-one for control and three for applications-were created. While the bulbs in the treatment groups were germinated with Zn at concentrations of 35, 70, and 140 mg/L, the bulbs in the control group were germinated with tap water. Germination was carried out at room temperature for 72 h and 144 h. When the allotted time was over, the root tips and leaf samples were collected and prepared for spectrophotometric measurements and macroscopic-microscopic examinations. Consequently, Zn treatment led to significant reductions in physiological indicators such as weight gain, root length, and germination percentage. Zn exposure caused genotoxicity by decreasing the MI ratios and increasing the frequency of MN and CAs (p < 0.05). Zn promoted various types of CAs in root tip cells. The most observed of CAs was the sticky chromosome. Depending on the dose, Zn was found to cause an increase in tail lengths in comet analyses, which led to DNA damage. Exposure to Zn led to a significant decrease in chlorophyll levels and an increase in MDA and proline levels. It also promoted significant increases in SOD and CAT enzyme activities up to 70 mg/L dose and statistically significant decreases at 140 mg/L dose. Additionally, Zn exposure caused different types of anatomical damage. The most severe ones are epidermis and cortex cell damage. Besides, it was found that the Zn dose directly relates to all of the increases and decreases in physiological, cytogenetic, biochemical, and anatomical parameters that were seen as a result of Zn exposure. As a result, it has been determined that the Zn element, which is absolutely necessary in trace amounts for the continuation of the metabolic activities of the organisms, can cause toxicity if it reaches excessive levels.
在这项研究中，研究了微量元素锌 (Zn) 在洋葱鳞茎测试材料中的毒性。从生理、细胞遗传学、生化和解剖学方面研究了毒性。发芽率、根长、增重、有丝分裂指数 (MI)、微核 (MN) 频率、染色体异常 (CAs)、丙二醛 (MDA)、脯氨酸和叶绿素水平、超氧化物歧化酶 (SOD) 和过氧化氢酶 (CAT) 酶活性以及分生组织细胞损伤被用作毒性指标。此外，还使用彗星试验来测量 DNA 损伤程度。创建了四组洋葱鳞茎——一组对照和三组应用。在处理组中，用浓度为 35、70 和 140 mg/L 的 Zn 发芽，而在对照组中，用自来水发芽。在室温下进行发芽 72 小时和 144 小时。时间结束后，收集根尖和叶片样本，准备进行分光光度测量和宏观-微观检查。结果，Zn 处理导致增重、根长和发芽率等生理指标显著降低。Zn 通过降低 MI 比值和增加 MN 和 CAs 的频率导致遗传毒性（p<0.05）。Zn 促进了根尖细胞中各种类型的 CAs。观察到的最常见的 CAs 是粘性染色体。根据剂量，Zn 被发现会导致彗星分析中尾巴长度增加，从而导致 DNA 损伤。暴露于 Zn 会导致叶绿素水平显著降低，MDA 和脯氨酸水平增加。它还促进 SOD 和 CAT 酶活性显著增加至 70 mg/L 剂量，在 140 mg/L 剂量下则显著降低。此外，Zn 暴露会导致不同类型的解剖损伤。最严重的是表皮和皮层细胞损伤。此外，还发现 Zn 剂量与 Zn 暴露导致的生理、细胞遗传学、生化和解剖参数的所有增加和减少直接相关。因此，已确定在痕量水平上对生物体代谢活动绝对必需的锌元素，如果达到过高水平，可能会产生毒性。
