High resolution microscopic mapping of DNA using multi-color fluorescent hybridization

We describe a procedure for microscopically mapping the relative positions of DNA probes along extended strands of DNA. The procedure referred to as direct visual hybridization (DIRVISH) DNA mapping involves the simultaneous hybridization of multiple probes and the fluorescent colors, red green and blue to produce images that convey high-resolution mapping information. The images appear as long strings of fluorescent signals positioned as they are in the genome. A visual multi-color map is generated within 2 days. Cosmid probes span a distance of 10 microms or more and have been observed to contain patterns within the strings of signals. We have developed computer imaging programs to scan through the strings of signals and plot the intensities. Scans through multiple signal strings for one cosmid probe revealed consistent patterns. We have interpreted the patterns as the result of suppression of repetitive DNA sequence hybridization. These patterns may prove useful as fingerprints for regions of DNA.