Novel approach for restriction mapping repetitive DNA elements using DNA transformation

We demonstrated that DNA transformation can be used to determine the linkage relationship between DNA restriction fragments in mouse genomic DNA. Using this experimental approach, we obtained linkage information which enabled us to construct a restriction map for the multiple thymidine kinase (tk) gene inserts present in a mouse L-cell line. This restriction map included cutting sites for seven restriction enzymes spanning a distance of over 10 kb. It revealed that the tk inserts in this cell line are arranged in a complex array consisting of direct and inverted repeats. In light of these results, we suggest that this approach will be particularly useful for restriction mapping DNA sequences that are repetitive as such DNA may be difficult to characterize by conventional methods alone.