The Two-dimensional Restriction Analysis of Drosophila DNAs: Males and Females

Two-dimensional restriction analysis has been applied to terminally labeled restriction segments from adult male and female flies that were the progeny of ten successive single-pair, brother-sister matings. Many of the 2500-4000 different bands that can be seen on autoradiographs are of widely different density, a fact that suggests the superposition of multiple restriction segments of similar sequence. The number of bands observed is significantly fewer than expected. Nearly all of the bands seen in male-DNA displays appear equivalent to those seen in female-DNA displays, but a few sex differences (male-dense and female-dense bands) can be identified--much fewer than expected. When the HpaII-MspI test was applied to fractionated BamHI fragments, between 900 and 1800 discrete C-C-G-G sites were found to be cleaved in a completely equivalent fashion by each isoschizomer.