Saxena P N, Chauhan L K S, Gupta S K
Cell Biology Division, Industrial Toxicology Research Centre, P.O. Box No. 80, M.G. Road, Lucknow 226001, India.
Toxicology. 2005 Dec 15;216(2-3):244-52. doi: 10.1016/j.tox.2005.08.008. Epub 2005 Sep 15.
To validate the use of Allium sativum as a sensitive test model for genotoxicity, the cytogenetic effects of a commercial formulation of the pyrethroid insecticide, cypermethrin, were evaluated in the root meristem cells of A. sativum. Ultraviolet (UV) and Fourier transform infrared (FTIR) spectral measurements were also carried out to understand the interaction of cypermethrin with DNA. In a preliminary toxicity assay, the EC50 for Allium root growth was estimated to be 8 ppm. For the cytogenetic assay, root meristem cells were exposed to 1, 2, 4, 8 and 16 ppm of the test compound for 24 h, and either processed immediately for analysis or incubated in water for 24 h of recovery and then processed. Cells analyzed immediately after the exposure had a significant, dose-dependent inhibition of mitotic index (MI) and induction of mitotic and chromosomal aberrations (MAs and CAs). The 24 h recovery period reduced the effect of the test compound on the MI and percent aberrations; however, cells exposed to 8 and 16 ppm showed a significant frequency of aberrations despite the recovery period. One part per million cypermethrin was consistently negative in the assay. The data indicate that higher doses of cypermethrin produce toxicity, CAs and MAs in A. sativum. The present study indicates that A. sativum is a sensitive and reliable test system. A bathochromic shift observed in UV absorption spectra reveals that cypermethrin binds with DNA. Role of vibrational modes of the active site in the recognition and reaction of cypermethrin with DNA has been discussed. Based on spectroscopic data and structural properties, a possible mechanism has been proposed for the interaction of cypermethrin with DNA resulting in chromosomal aberrations.
为验证大蒜作为遗传毒性敏感测试模型的用途，在大蒜的根尖分生组织细胞中评估了拟除虫菊酯类杀虫剂氯氰菊酯商业制剂的细胞遗传学效应。还进行了紫外（UV）和傅里叶变换红外（FTIR）光谱测量，以了解氯氰菊酯与DNA的相互作用。在初步毒性试验中，大蒜根生长的半数有效浓度（EC50）估计为8 ppm。在细胞遗传学试验中，将根尖分生组织细胞暴露于1、2、4、8和16 ppm的受试化合物中24小时，然后立即进行分析处理，或者在水中孵育24小时进行恢复，然后再进行处理。暴露后立即分析的细胞有丝分裂指数（MI）受到显著的剂量依赖性抑制，且有丝分裂和染色体畸变（MA和CA）诱导增加。24小时的恢复期降低了受试化合物对MI和畸变率的影响；然而，暴露于8和16 ppm的细胞尽管经过恢复期仍显示出显著的畸变频率。百万分之一的氯氰菊酯在试验中始终呈阴性。数据表明，较高剂量的氯氰菊酯会在大蒜中产生毒性、CA和MA。本研究表明，大蒜是一个敏感且可靠的测试系统。紫外吸收光谱中观察到的红移表明氯氰菊酯与DNA结合。讨论了活性位点振动模式在氯氰菊酯与DNA识别和反应中的作用。基于光谱数据和结构特性，提出了氯氰菊酯与DNA相互作用导致染色体畸变的可能机制。
