EXPRESSION OF GENETIC VARIATION IN CULTURED CELLS

这项研究的基本目标是确定 突变外事件，如有丝分裂重组，基因失活， 染色体重排、缺失或染色体分离 隐性突变在培养的哺乳动物细胞中的表达。我们的 最终目标是清楚地了解细胞过程和 可遗传变异的产生和表达机制 在哺乳动物的体细胞中，并定义了这些过程在 癌变的起始和促进阶段。结合古典 利用重组DNA技术的体细胞遗传学方法，我们将 研究染色体重排对基因表达和基因表达的影响 突变或缺失。我们将利用DNA介导的基因转移来研究 基因的表达和可变性如何受其染色体的影响 并对转入的中国仓鼠aprt基因 序列与内源CHO aprt基因的敏感性不同 突变、失活或缺失。此外，我们建议利用 具有四种不同连锁基因或基因的杂合子细胞系 细胞遗传学标记分析有丝分裂重组、基因失活、 染色体重排、缺失或染色体分离事件 导致aprt-隐性突变表型在水稻中的表达 诱变剂处理或未处理的对照细胞培养。我们将使用这个 确定额外突变事件是否由已知的 肿瘤启动者或促进者。这些实验应该提供 有关细胞过程和机制的信息，涉及 肿瘤的启动和促进。

The basic objective of this research is to determine the roles of extra-mutational events, such as mitotic recombination, gene inactivation, chromosomal rearrangements, deletions, or chromosome segregation, in the expression of recessive mutations in cultured mammalian cells. Our ultimate goal is a clear understanding of the cellular processes and mechanisms involved in the generation and expression of heritable variation in mammalian somatic cells, and definition of the role of such processes in the initiation and promotion stages of carcinogenesis. Combining classical somatic cell genetic approaches with recombinant DNA technologies, we will study the effects of chromosomal rearrangements on gene expression and mutation or deletion. We will utilize DNA-mediated gene transfer to study how the expression and mutability of a gene are affected by its chromosomal environment, and to determine whether transferred Chinese hamster APRT gene sequences differ from the endogenous CHO APRT genes in their susceptibility to mutation, inactivation, or deletion. In addition, we propose to utilize a cell line that is heterozygous for four different linked genetic or cytogenetic markers to assay mitotic recombination, gene inactivation, chromosomal rearrangements, deletions, or chromosome segregation events leading to the expression of APRT- recessive mutant phenotypes in mutagen-treated or untreated control cell cultures. We will use this system to determine whether extra-mutational events are induced by known tumor initiators or promoters. These experiments should provide information concerning the cellular processes and mechanisms involved in tumor initiation and promotion.