title: The in situ formation of DNA-DNA duplexes of drosophila virilis satellite DNA.
abstract: The DNA of Drosophila virilis brains and imaginal discs was labeled in vitro to a specific activity of 6 X 10(-5) dpm/mug, using an organ culture medium. The DNA was fractionated on neutral and alkaline CsC1 gradients and the heavy strands of satellite I annealed in situ to denatured polytene chromosomes from squash preparations of larval salivary glands. Nuclease S1 from Aspergillus oryzae was used to digest the unpaired ssDNA, resulting in a distinct labeling of the alpha-heterochromatin in the chromocenter and a small amount of diffused labeling in the proximal beta-heterochromatic part of the X-Chromsome.
mesh_terms: D000818:Animals; D001483:Base Sequence; D002499:Centrifugation, Density Gradient; D002875:Chromosomes / Q000032:analysis*; D004247:DNA / Q000032:analysis*; D004276:DNA, Satellite / Q000032:analysis* / Q000302:isolation & purification; D006570:Heterochromatin / Q000032:analysis; D066298:In Vitro Techniques; D009693:Nucleic Acid Hybridization
chemical_list: D004276:DNA, Satellite; D006570:Heterochromatin; D004247:DNA