基因打靶及其应用

用活细胞染色体DNA可与外源性DNA同源序列发生同源重组的性质，达到定点修饰改造染色体某基因的目的，此法称基因打靶．基因的同源重组是较普遍的生物现象，其分子机理尚未阐明，但活细胞内确有一酶系可使DNA的同源序列在细胞内发生重组，这一事实已无可争辨．此事实为基因打靶的理论基础．基因打靶技术操作的关键是建立一含筛选基因的重组载体，并有效地把它转入细胞核内．基因打靶命中的细胞可稳定遗传．基因打靶在改造生物品种，一些复杂生命现象（如发育的分子机制等）及临床理论研究均有广阔的前景．

Gene Targeting and Its Application

In living cells,exploiting homologous recombination between sequences both from genomic DNA and extracellular DNA to accomplish site-modification in a certain gene on chromosome,is a method called gene targeting.Although the molecular mechanism of DNA homologous recombination is far from being elucidated, it is a common biological phenomenon.It is true that in cells there is an enzyme system that plays the role to make recombination of homologous DNAs, which is the theoretical foundation of gene targeting. The technology of gene targeting has been fully developed. The key step for operation is to construct a recombinant carrier including one or two genes for selection and to transfer it into the nucleus effectively. The targeted cells can be inherited stably. Gene targeting has promising prospects in production of new strains of living things, in clinical usage and in theoretical research of some complicated biological phenomena such as the molecular mechanism of development.