Evans H H, Horng M F, Beer J Z
Mutat Res. 1986 Jun;161(1):91-7. doi: 10.1016/0027-5107(86)90103-x.
In previous studies, the two closely related strains of L5178Y (LY) mouse lymphoma cells, LY-R and LY-S, have been shown to differ in their sensitivity to UV and ionizing radiation. Thus, in comparison to strain LY-R, strain LY-S has been found to be more sensitive to the lethal effects of ionizing radiation, more resistant to the lethal effects of UV radiation, but less mutable at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus by both UV and X-radiation. In the present work, the lethal and mutagenic effects of ethyl methanesulfonate (EMS), methyl nitrosourea (MNU) and UV radiation (254 nm) were compared in the two strains. Mutability at the Na+/K+-ATPase locus as well as the HGPRT locus was determined. As previously reported, we found strain LY-S to be more resistant than strain LY-R to the lethal effects of UV radiation. In contrast, strain LY-S was more sensitive to the cytotoxic effects of the two alkylating agents. In spite of these differences in sensitivity, we found strain LY-S to be less mutable than strain LY-R by all 3 agents at the HGPRT locus. At the Na+/K+-ATPase locus, strain LY-S was also less mutable than strain LY-R by equal concentrations of EMS and UV radiation and by equitoxic concentrations of MNU. However, the difference between the strains was much more pronounced at the HGPRT locus than at the Na+/K+-ATPase locus. We have suggested that the interaction of unrepaired lesions in strain LY-S tends to cause an excess of deletions and multilocus effects, which in turn result in a locus-dependent decrease in the recovery of viable LY-S mutant cells.
在先前的研究中，L5178Y（LY）小鼠淋巴瘤细胞的两个密切相关菌株LY - R和LY - S，已被证明对紫外线和电离辐射的敏感性不同。因此，与LY - R菌株相比，已发现LY - S菌株对电离辐射的致死效应更敏感，对紫外线辐射的致死效应更具抗性，但在次黄嘌呤 - 鸟嘌呤磷酸核糖转移酶（HGPRT）位点经紫外线和X射线照射后更不易发生突变。在本研究中，比较了甲磺酸乙酯（EMS）、甲基亚硝基脲（MNU）和紫外线辐射（254nm）在这两个菌株中的致死和诱变效应。测定了Na⁺/K⁺ - ATP酶位点以及HGPRT位点的突变率。如先前报道的那样，我们发现LY - S菌株比LY - R菌株对紫外线辐射的致死效应更具抗性。相反，LY - S菌株对两种烷化剂的细胞毒性效应更敏感。尽管在敏感性上存在这些差异，但我们发现LY - S菌株在HGPRT位点经所有三种试剂处理后比LY - R菌株更不易发生突变。在Na⁺/K⁺ - ATP酶位点，相同浓度的EMS和紫外线辐射以及等毒性浓度的MNU处理后，LY - S菌株也比LY - R菌株更不易发生突变。然而，菌株之间的差异在HGPRT位点比在Na⁺/K⁺ - ATP酶位点更为明显。我们认为，LY - S菌株中未修复损伤的相互作用倾向于导致过多的缺失和多位点效应，进而导致存活的LY - S突变细胞的恢复出现位点依赖性降低。
