In this study, we have shown that the combination of intratubular DNA injection followed by in vivo EP results in the efficient delivery of foreign genes into various types of spermatogenic cells. Mammalian spermatogenesis is an excellent model system with which to study specific gene expression during differentiation of a defined cell lineage as well as to study the molecular mechanism responsible for switching from mitotic to meiotic cell division. However, because of unsolved difficulties in culturing and manipulating spermatogenic cells in vitro, we have no choice but to make transgenic mice for the functional analyses of such spermatogenic genes. buy cipro
Our EP transfection system will provide a new method that is much easier and more time-saving than transgenic techniques, at least for a transient expression assay to specify an enhancer and/or promoter sequence of such a gene. In fact, the present study has illustrated that the Prm-1 enhancer, which has been shown to be a cis-element responsible for spermatid stage-specific gene expression in transgenic analyses, exhibited significant elevation of the reporter expression compared to that of the enhancerless form using the EP transfection method. Furthermore, cell-type-specific reporting was also proven by histochemical analysis. The p-gal-pos-itive cells in the seminiferous tubule-transfected Prm-lacZ were restricted to within the haploid spermatid cell layer (Fig. 2).