The project was designed to develop and apply a novel unconventional approach to genome mapping based on physical properties of DNA that are a sensitive function of the base sequence, and so does not depend on the clonability of the sequences to be mapped nor on the presence of particular restriction sites. We have shown that a broad array of DNA fragments are retarded at nearly the same level in denaturing gradient gel electrophoresis (DGGE) if the segment with the lowest thermal stability has the same melting temperature, regardless of the length of the fragment. The retarded pattern remain steady in the gel, changing little with continued field exposure. Mapping proceeds by the analysis of two-dimensional patterns produced by random fragmentation of genomic DNA and denaturing gradient gel electrophoresis. Random fragments are first separated according to length by conventional agarose electrophoresis. The result is a two- dimensional pattern which can be idealized as an array of nearly parallel, mostly separated lines of DNA. The pattern is blotted onto a membrane and probed sequentially with oligos or relevant DNA or RNA fragments. The endpoints on the fragment length scale of each line hybridizing with each probe, the distribution along each line, …