HIGH-RESOLUTION MICROSCOPIC MAPPING OF DNA USING MULTICOLOR FLUORESCENT HYBRIDIZATION

We describe a procedure for microscopically mapping the relative posit ions of DNA probes along extended strands of DNA. The procedure referr ed to as direct visual hybridization (DIRVISH) DNA mapping involves th e simultaneous hybridization of multiple probes and the fluorescent co lors, red, green and blue to produce images that convey high-resolutio n mapping information. The images appear as long strings of fluorescen t signals positioned as they are in the genome. A visual multi-color m ap is generated within 2 days. Cosmid probes span a distance of 10 mu m or more and have been observed to contain patterns within the string s of signals. We have developed computer imaging programs to scan thro ugh the strings of signals and plot the intensities. Scans through mul tiple signal strings for one cosmid probe revealed consistent patterns . We have interpreted the patterns as the result of suppression of rep etitive DNA sequence hybridization. These patterns may prove useful as fingerprints for regions of DNA.