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XB-ART-30581
Biochim Biophys Acta 1982 Aug 30;6982:204-10.
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Cloning in a cosmid vector of complete 37 kb and 25 kb ribosomal DNA repeat units from the chicken.

Mattaj IW , Mackenzie A , Jost JP .


Abstract
DNA fragments of up to 40 kb containing rRNA-coding sequences have been isolated from a chicken liver DNA library prepared in the cosmid pHC79. Characterization of the cloned DNA by R-loop and restriction mapping has shown that there are two size classes of repeat unit, one of 37 kb and one of 25 kb, the larger of which is a family of units which vary slightly in size. These two classes were shown to be present in the DNA of a single chicken. The size of the internal transcribed spacer in the chicken was measured to be 4.4 kb from analysis of R-loops and heteroduplexes between chicken and Xenopus laevis rDNAs. No introns were observed in either the 18 S or the 28 S coding sequences. The number of copies of the chicken rDNA unit was measured by titration against the cloned sequences to be 202 +/- 51 per haploid genome.

PubMed ID: 6289899
Article link: Biochim Biophys Acta