Recently, in vivo gene transfer techniques have become popular as a tool for gene therapy and biological analysis at the whole-organ level, and several different methods have been developed thus far. Virus-mediated gene transfer is the most widely used because of its high gene transfer efficiency; however, it is a high-risk biohazard. In contrast, nonviral vectors such as lipid-mediated systems are safe and easy, but the transfection efficiency is relatively low. Another nonviral method, in vivo electroporation (EP), has been shown to be an efficient method for transferring genes to the tissues of living animals. This system indiscriminately delivers DNA molecules into any type of tissue cell and has a markedly higher transfer efficiency than other nonviral transfer systems. ampicillin antibiotic
In this study, as a possible alternative method for generating transgenic mice, we investigated an in vivo EP method using the testes of living mice to develop a simple assay system with which to analyze the regulatory elements of spermatogenic specific genes. A combination of foreign DNA injection into the seminiferous tubules and subsequent EP demonstrated an efficiency high enough for a transient expression assay to detect the activities of sper-matogenic specific enhancer elements, which also enabled us to detect the histological distribution of cells expressing the transgenes.