Migration Groups: A Poorly Explored Point of View for Genetic Damage Assessment Using Comet Assay in Human Lymphocytes

Abstract

A new point of view for genetic damage assessment using the comet assay is proposed based on the number of migration groups, the number of comets in each group, and the groups with the highest number of comets. Human lymphocytes were exposed to different concentrations of Methyl Methane Sulfonate (MMS), Maleic Hydrazide (MH), 2,4-Dichlorophenoxyacetic (2,4-D), and N-nitroso diethylamine (NDEA). Using comet assay, the migration means of the comets were determined and later grouped arbitrarily in migration groups with no higher differences than 1 µc. The number of migration groups, the number of comets in each group, and the groups with the highest number of comets (modes) were determined. All four of the genotoxic agents studied showed a significant increase (p < 0.05) in the tail length and the number of migration groups compared to the negative control. The number of migration groups did not show a significant variation between the four-genotoxic agents nor within their different concentrations. However, the comparison of the modes did show differences between the genotoxic agents, but not within the concentrations of a same genotoxic agent, which indicated a determined chemical interaction on the DNA. These parameters can improve the detection of genetic damage associated with certain genotoxic agents.

Evaluation of Genetic Damage and Antigenotoxic Effect of Ascorbic Acid in Erythrocytes of Orochromis niloticus and Ambystoma mexicanum Using Migration Groups as a Parameter

“…The comet test is a popular tool used to detect genetic damage [1] and there are several parameters used in this test such as tail length and tail moment [33]. Although the comet test is a well-established test in genetic research [3], its full potential to quantify heterogeneity in response to genotoxic agents has not been exploited [10]; for this reason, Reynoso-Silva et al [22] proposed a new parameter to detect genetic damage, called the MG. In an effort to assess the ability of the MG as a parameter to detect genetic damage, Oreochromis niloticus and Ambystoma mexicanum erythrocytes were exposed in vitro to the genotoxic agents EMS and UV-C; additionally, the antigenotoxic effect of AA was assessed.…”

“…The evaluation of MGs, using the tail length, as a product of the heterogeneity in the length of the comets, allows characteristic genetic damage to be evaluated in response to specific genotoxic agents [22]. For example, UV-C generates MGs with comet cells between 130 and 182, while EMS does it between 106 and 118.…”

“…To take advantage of the heterogeneity of genetic damage observed in the comet test, the grouping method proposed by Reynoso-Silva et al was used [22]. Additionally, Microsoft Excel 2019 software was utilized to form MGs with comet cells.…”

“…However, despite these research advances, it is currently considered that the full potential of the comet test to detect heterogeneity in response to genetic damage has not been exploited, since only the average result is used and heterogeneity loses relevance [10,22]. Reynoso-Silva et al [22] proposed a new parameter to detect genetic damage, called MGs, which take advantage of the heterogeneity of genetic damage and do not use only the average migration of the tail. It is based on the formation of groups of comets with a similar tail length and allows the use of visual scoring analysis and computerized programs.…”

“…It was also was observed that the number of MGs is directly proportional to the genetic damage as well as the concentration of the genotoxic agent. MGs have not been deeply studied and could be related to the different sensitivities of cells in response to DNA damage and/or repair due to a specific agent [22] so it is necessary to investigate the advantages that this new parameter can have. Here, the comet assay system was used to evaluate the genetic damage induced by EMS and UV-C, as well as the post-treatment protective effects of AA in UV-C-exposed blood cells of Oreochromis niloticus and Ambystoma mexicanum using the tail length, the tail moment, and the MG parameter.…”