Suppr超能文献

甲磺酸乙酯和丝裂霉素C诱导的L5178Y小鼠淋巴瘤细胞tk位点突变的分子分析

Molecular analysis of mutations at the tk locus of L5178Y mouse-lymphoma cells induced by ethyl methanesulphonate and mitomycin C.

作者信息

Davies M J, Phillips B J, Rumsby P C

机构信息

BIBRA Toxicology International, Carshalton, Surrey, UK.

出版信息

Mutat Res. 1993 Dec;290(2):145-53. doi: 10.1016/0027-5107(93)90154-8.

Abstract

Mutations at the tk locus of mouse-lymphoma L5178Y cells were induced by treatment with ethyl methanesulphonate (EMS), primarily a point mutagen and mitomycin C (MMC), a potent clastogen. Mutant colony size was distinctly bimodal with 35% of spontaneous mutants growing as small colonies and 65% large. The proportion of small colonies increased only slightly to 41% in EMS-treated cultures but to 64% after MMC treatment. Mutations were analysed by Southern and Northern blotting. Digestion of DNA with the restriction enzyme, Nco I, revealed that many mutants had lost a 6.3-kb fragment which constituted the loss of the entire tk gene. Almost all of the EMS-induced large-colony mutants analysed (9/10) retained the tk+ allele suggesting the presence of an intragenic mutation. Of the small-colony mutants, half (6/12) had lost the tk+ gene and presumably other genes affecting growth and half retained the tk+ allele suggesting point mutations in both the tk gene and other sites in the genome affecting growth. A very different spectrum of mutation was induced with MMC. Only 1/12 of the large-colony mutants were due to intragenic mutation, the remaining large-colony mutants having lost the tk+ allele while all the small-colony mutants had lost the tk+ gene presumably with the deletion extending to genes essential for normal growth. Northern blot analysis showed no changes in the size of tk transcript in any mutants. Alterations in the amount of tk mRNA were not detectable since all mutants produced an mRNA of similar size and amount, which may indicate the production of an abnormal mRNA from the tk- allele. Unlike cell-mutation assays that use hemizygous loci (such as hprt+/0) for detecting potential chemical carcinogens, the mouse-lymphoma tk+/- assay allows the recovery of both intragenic and intergenic mutations thus enabling the detection of both point mutagens such as EMS and potent clastogens like MMC.

摘要

用甲磺酸乙酯(EMS,主要是一种点突变剂)和丝裂霉素C(MMC,一种有效的致断裂剂)处理小鼠淋巴瘤L5178Y细胞,诱导其tk基因座发生突变。突变菌落大小明显呈双峰分布,35%的自发突变体长成小菌落,65%长成大菌落。在EMS处理的培养物中,小菌落的比例仅略有增加,达到41%,但在MMC处理后则增加到64%。通过Southern印迹和Northern印迹分析突变。用限制性内切酶Nco I消化DNA显示,许多突变体丢失了一个6.3kb的片段,这意味着整个tk基因的缺失。几乎所有分析的EMS诱导的大菌落突变体(9/10)都保留了tk+等位基因,表明存在基因内突变。在小菌落突变体中,一半(6/12)丢失了tk+基因,可能还有其他影响生长的基因,另一半保留了tk+等位基因,表明tk基因和基因组中其他影响生长的位点都发生了点突变。MMC诱导的突变谱非常不同。大菌落突变体中只有1/12是由于基因内突变,其余大菌落突变体丢失了tk+等位基因,而所有小菌落突变体都丢失了tk+基因,推测缺失延伸到了正常生长所必需的基因。Northern印迹分析显示,任何突变体中tk转录本的大小都没有变化。由于所有突变体产生的mRNA大小和数量相似,因此无法检测到tk mRNA量的变化,这可能表明从tk-等位基因产生了异常mRNA。与使用半合子基因座(如hprt+/0)检测潜在化学致癌物的细胞突变试验不同,小鼠淋巴瘤tk+/-试验能够检测基因内和基因间的突变,从而能够检测出EMS等点突变剂和MMC等有效的致断裂剂。

文献AI研究员

20分钟写一篇综述,助力文献阅读效率提升50倍。

立即体验

用中文搜PubMed

大模型驱动的PubMed中文搜索引擎

马上搜索

文档翻译

学术文献翻译模型,支持多种主流文档格式。

立即体验