1. Human Ribosomal RNA Genes: Orientation of the Tandem Array and Conservation of the 5′ End
- Author
-
Huntington F. Willard, Sharon Bodrug, Roy D. Schmickel, Vanora Kean, Peter N. Ray, James E. Sylvester, Ian Dubé, Joanne Sutherland, Ronald G. Worton, and Catherine Duff
- Subjects
Chromosomes, Human, Pair 14 ,Genetics ,Chromosomes, Human, Pair 15 ,Multidisciplinary ,Concerted evolution ,Chromosomes, Human, Pair 13 ,Transcription, Genetic ,Chromosomes, Human, Pair 21 ,Chromosomes, Human, Pair 22 ,Ribosomal RNA ,Biology ,Biological Evolution ,DNA, Ribosomal ,Restriction map ,Genes ,Tandem repeat ,RNA, Ribosomal ,Sequence Homology, Nucleic Acid ,Humans ,Gene family ,Cloning, Molecular ,Gene ,Ribosomal DNA ,Repeat unit - Abstract
The multiple copies of the human ribosomal RNA genes (rDNA) are arranged as tandem repeat clusters that map to the middle of the short arms of chromosomes 13, 14, 15, 21, and 22. Concerted evolution of the gene family is thought to be mediated by interchromosomal recombination between rDNA repeat units, but such events would also result in conservation of the sequences distal to the rDNA on these five pairs of chromosomes. To test this possibility, a DNA fragment spanning the junction between rDNA and distal flanking sequence has been cloned and characterized. Restriction maps, sequence data, and gene mapping studies demonstrate that (i) the rRNA genes are transcribed in a telomere-to-centromere direction, (ii) the 5' end of the cluster and the adjacent non-rDNA sequences are conserved on the five pairs of chromosomes, and (iii) the 5' end of the cluster is positioned about 3.7 kb upstream from the transcription initiation site of the first repeat unit. The data support a model of concerted evolution by interchromosomal recombination.
- Published
- 1988
- Full Text
- View/download PDF