Direct sequencing of flanking regions of a transgene amplified by inverted PCR.

In transgenic mice, recombinant DNAsmicroinjected into pronuclei of fertilized eggs are generally integrated into host chromosomes.1} The integration mechanism of microinjected DNA is not fully understood because of limited information concerning the structures of integrated foreign DNAs(transgenes) and their flanking chromosomalDNAs.Transgenes of a few transgenic mice and their flanking regions have been cloned and analyzed.2~6) However, these methods included time-consuming steps, such as construction of genomic libraries, cloning, and subcloning. We have reported that polymerase chain reaction (PCR)7) and inverted PCR (IPCR)8~10) techniques were