Guo Xiaoqing, Chen Ying, Moore Martha M, Mei Nan
Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, USA.
Ramboll, US Corporation, Little Rock, AR, USA.
Methods Mol Biol. 2020;2102:251-270. doi: 10.1007/978-1-0716-0223-2_14.
The mouse lymphoma assay (MLA), a forward mutation assay using the Tk-3.7.2C clone of the L5178Y mouse lymphoma cell line and the Thymidine kinase (Tk) gene, has been widely used as an in vitro genetic toxicity assay for more than four decades. The MLA can evaluate the ability of mutagens to induce a wide range of genetic events including both gene mutations and chromosomal mutations and has been recommended as one component of several genotoxicity test batteries. Tk-deficient mutants often exhibit chromosomal abnormalities involving the distal end of chromosome 11 where the Tk gene is located, in mice, and the type of chromosome alteration can be analyzed using a loss of heterozygosity (LOH) approach. LOH has been considered an important event in human tumorigenesis and can result from any of the following several mechanisms: large deletions, mitotic recombination, and chromosome loss. In this chapter, the authors describe the procedures for the detection of LOH in the Tk mutants from the MLA, and apply LOH analysis for understanding the types of genetic damage that is induced by individual chemicals.
小鼠淋巴瘤试验（MLA）是一种正向突变试验，使用L5178Y小鼠淋巴瘤细胞系的Tk - 3.7.2C克隆和胸苷激酶（Tk）基因，四十多年来一直被广泛用作体外遗传毒性试验。MLA可以评估诱变剂诱导包括基因突变和染色体突变在内的广泛遗传事件的能力，并被推荐作为几种遗传毒性试验组合的一个组成部分。在小鼠中，Tk缺陷型突变体通常表现出涉及Tk基因所在的11号染色体远端的染色体异常，并且可以使用杂合性缺失（LOH）方法分析染色体改变的类型。LOH被认为是人类肿瘤发生中的一个重要事件，可能由以下几种机制中的任何一种引起：大片段缺失、有丝分裂重组和染色体丢失。在本章中，作者描述了从小鼠淋巴瘤试验的Tk突变体中检测LOH的程序，并应用LOH分析来了解由单个化学物质诱导的遗传损伤类型。
