| Abstract: | The embryonic stem (ES) cell system in combination with gene targeting have become an important approach to studying gene function in vivo. Many important genes were knocked out through this system. Establishment of ES cell lines, introduction of foreign genes into ES cells and production of germline chimeras are three important links of ES cell system. Of them, the production of germline chimeras is most important. Because the production of ES cell system needs complicated techniques and strict experimental conditions, no formal report was published in China at present, although hundreds of gene knock out experiments were reported in the world. Now, we report the successful production of germline chimeras in China. By using HM 1 cells and three kinds of mouse embryos (C57BL/6J, ICR, KM), manipulating 207 embryos, two germline chimeras were obtained. Studying two factors (feeder cells and host embryo) affecting the production of chimeras, two results were found: 1)embryos of C57BL/6J mice were more fit for producing chimeras than that of KM and ICR; 2) using STO feeder cells and C57BL/6J as host embryos, the rate of producing chimeric mice was low (9.7%), however, using MEF feeder cells, the rate was significantly improved (48.6%). Our work suggested that the number of ES cells which could form germline chimeras was improved in the total number of ES cells when the STO feeder layers were changed into the MEF layers. |
