title: Organization of the ribosomal RNA genes of Dictyostelium discoideum: mapping of the nontranscribed spacer regions.
abstract: Most of the Dictyostelium ribosomal nontranscribed spacer DNA has been mapped using Eco R1, Hind III, and Sal I restriction digests and recombinant plasmids containing parts of the rDNA (ribosomal DNA). The repeat units are at least 42 kb (1 kilobase = 1000 base pairs = 1 kb) long; of this, 8 kb codes for the 36S rRNA precursor. The repeat units give a homogeneous pattern of Sal I, Eco R1, and Hind III restriction fragments. The repeats could be linked by a heterogeneous region in the nontranscribed spacer, not tandemly repeated, or linked in a more complicated structural arrangement. The total rDNA comprises at least 18% of the nuclear DNA.
mesh_terms: D000818:Animals; D002874:Chromosome Mapping; D004247:DNA; D004262:DNA Restriction Enzymes; D004274:DNA, Recombinant; D004023:Dictyostelium / Q000378:metabolism*; D005796:Genes; D009235:Myxomycetes / Q000378:metabolism*; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D012335:RNA, Ribosomal / Q000096:biosynthesis*
chemical_list: D004274:DNA, Recombinant; D012335:RNA, Ribosomal; D004247:DNA; D004262:DNA Restriction Enzymes