title: Ribosomal RNA cistrons in Allomyces arbuscula.
abstract: Bulk and nuclear DNA have been fractionated by preparative neutral CsCl equilibrium density gradient centrifugation and each fraction hybridized to labeled rRNA (25 + 18 S). The cistrons coding for rRNA appeared on the light side of the main peak. Hybridization of the nuclear DNA fractionated by preparative Ag+-Cs2SO4 gradients at different pHs showed that the banding profile did not change as compared to the CsCl pattern. In Hg2+-Cs2SO4 gradients, however, the peak of the fRNA-DNA hybrids shifted on the heavier side of the profile. This indicates that the ribosomal RNA cistrons in Allomyces are A-T-rich. Hybridization with homologous rRNA showed that, at saturation, 3.25% of the DNA is complementary to rRNA. With the genome size of 1.7-10(10) daltons, the multiplicity of rRNA cistrons has been found to be close to 270.
mesh_terms: D001483:Base Sequence; D002499:Centrifugation, Density Gradient; D008411:Chytridiomycota / Q000235:genetics*; D004247:DNA / Q000235:genetics*; D004276:DNA, Satellite / Q000235:genetics; D005658:Fungi / Q000235:genetics*; D005796:Genes; D006358:Hot Temperature; D009693:Nucleic Acid Hybridization; D012335:RNA, Ribosomal / Q000235:genetics*
chemical_list: D004276:DNA, Satellite; D012335:RNA, Ribosomal; D004247:DNA