Interactive computer-aided assignment of multiple probes to cytogenetic bands by simultaneous dual color fluorescence in situ hybridization and DAPI banding

A macro function was developed to run in conjunction with the popular image analysis package NIH Image, to allow simultaneous determination of mapping positions of one or two separate probes with respect to cytogenetic bands by dual color fluorescence in situ hybridization (FISH) and DAPI banding, and by determination of their fractional distance from pter (FLpter). In order to allow maximal flexibility, a user-defined line along the chromosome is used for measurements. Algorithms were developed to detect the ends of the chromosome and the cytogenetic bands. Results of the analysis are presented in graphical form, comprising a display of the DAPI intensity along the chromosome, the positions of the probe(s), the locations of bands as determined by analysis of the second derivative of the DAPI intensity profile, and a standard ideogram of the chromosome for comparison. The approach was validated and compared to visual assignment of probes to DAPI bands using the cosmid clone PYGM, which has been previously mapped to chromosome 11q13, and has been used as a landmark for mapping of other probes (3).