[Production of mammary gland bioreactor by gene targeting of somatic cells].

Producing mammary gland bioreactor showed great advantage over many years, but the level of transgenic expression was low in transgenic animals and the diversity was more great because of the position effect of transgene and the artificial recombination of the gene elements. Gene targeting based on the principle of gene homologous recombination had been studied and applied, because the transgene could be integrated precisely in the chromosome. This review summary the current status of producing mammary gland bioreactor by the technology of gene targeting and nuclear transfer using the somatic cell lines. These aspects were discussed, including the characteristic and difficulties of gene targeting, the strategies to improve the efficiency of gene targeting, the different features of between the strategy of promoter-trap and the Cre-LoxP system, etc; for the others, how to select the cell lines with the different strategies of gene targeting, how to raise the times of cell lines that was cultured after the gene targeting. Somatic cell nuclear transfer offers new and exciting opportunities in the areas of the gene targeting. However, the field as a whole is still difficult and complex. In this paper, we described recent advances and novel approaches, which resulted in progress during the last year. Key problems hindering further progress are addressed, for example, how to increase the efficiency of nuclear transfer. With the technology of gene targeting and nuclear transfer, it should provide a general way to produce specific genetic changes in several mammalian species. We are clearly at the dawn of a new era in mammalian genetic technology.