The longitudinal differentiation produced by photo-oxidation and acridine-orange staining in eukaryote chromosomes: role and involvement of DNA base composition.

Photo-oxidation and staining with acridine-orange result in a longitudinal green/orange-red/brown-red color differentiation in fixed chromosomes of Drosophila melanogaster, D. virilis, Culiseta longiareolata, and Mus musculus. Such a result has been correlated with specific DNA base sequences situated in specific chromosomal areas. In fact, given the known base composition of satellite DNA's in three of the species we studied, a correspondence seems to exist between molecular hybridization in situ of AT-rich satellite DNA's and the location of specific stain reactions in specific chromosome regions. Moreover, our results support previous findings suggesting preferential guanine destruction as a consequence of photo-oxidation.