IDENTIFICATION OF GERM-LINE CHIMERAS BY POLYMERASE CHAIN-REACTION ANDISOENZYME ANALYSIS OF MOUSE SPERMATOZOA

In this study a rapid, simple and inexpensive procedure is described w hich allows potential germ-line male mice to be identified with confid ence. Spermatozoa recovered by uterine washing following mating with n ormal female mice was analysed in two ways. First, the patterns of exp ression of the different isoforms of glucose phosphate isomerase were determined. Since the glucose phosphate isomerase isoforms expressed i n embryo stem (ES) cell lines are frequently different from those asso ciated with the host blastocyst, it is possible to determine the propo rtion of spermatozoa produced by an individual animal that was of ES c ell or host-blastocyst origin. Second, DNA of spermatozoa was subjecte d to polymerase chain reaction (PCR) analysis using primers with speci ficity for the targeted mutation in the ES cells. The PCR analysis was particularly valuable in identifying germ cell chimaeras in which the contribution of ES-derived spermatozoa was significantly less than th at specified by the host blastocyst.