Generation of transgenic mice by DNA microinjection has become one of the most important technologies in studying gene function in vivo. Ran- dom integration of transgene often results in inser- tional mutation which may complicate phenotype analysis of transgenic mice and/or create a good opportunity to study the function of endogenous gene. However,the utilization of these potentially valuable resources is hampered due to lack of efficient ap- proaches for rapid identification of multi-copy trans- gene integration sites. Here we propose two PCR-based approaches to identifying trans- gene/genome junction sequences. The efficiency of these two strategies was tested in 9 independent transgenic mouse lines. Among them,the transgene in 8 mouse lines was clearly localized to certain chromosome regions. These rapid and efficient ap- proaches will greatly facilitate the study of insertional mutation due to transgene integration.
