title: Structure and organization of ribosomal DNA.
abstract: Three trends are seen in the organization of ribosomal DNA genes during evolution: 1) gradual separation and separability of the regulation of transcription of 5S and larger subunit rRNAs; 2) retention of a transcription unit containing both large and small rRNAs; and 3) clustering of genes for both 5S and 18S-28S rDNAs, with the possible association of other 'non-rDNA' in the clusters of 18S-28S rDNA genes by the time mammals evolve.
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO 63110.
authors.forename: A K
authors.initials: AK
authors.lastname: Srivastava
authors.forename: D
authors.initials: D
authors.lastname: Schlessinger
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004275:DNA, Ribosomal / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D008322:Mammals / Q000235:genetics; D012335:RNA, Ribosomal / Q000235:genetics*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D012339:RNA, Ribosomal, 28S / Q000235:genetics; D012341:RNA, Ribosomal, 5S / Q000235:genetics; D014158:Transcription, Genetic; D015003:Yeasts / Q000235:genetics; D012407:rRNA Operon / Q000235:genetics*
chemical_list: D004275:DNA, Ribosomal; D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D012337:RNA, Ribosomal, 18S; D012338:RNA, Ribosomal, 23S; D012339:RNA, Ribosomal, 28S; D012341:RNA, Ribosomal, 5S