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. 1978 Jul;75(7):3312–3316. doi: 10.1073/pnas.75.7.3312

Free ribosomal RNA genes in Paramecium are tandemly repeated.

R C Findly, J G Gall
PMCID: PMC392765  PMID: 277929

Abstract

The genes coding for 17S and 25S rRNA in Paramecium tetraurealia were isolated. The macronuclear ribosomal DNA (rDNA) exists as relatively small, extrachromosomal molecules with both linear and circular forms. Electron microscopy and restriction endonuclease analysis revealed that the rDNA is arranged as tandem repeats with an average repeat size of 5.5 X 10(6) daltons. Some heterogeneity of repeat lengths was found both by electron microscopy and by restriction enzyme analysis. The rDNA does not snap back after denaturation. This study provides additional evidence that extrachromosomal rDNA may be a common feature among lower eukaryotes. However, in contrast to several other cases, the rDNA of Paramecium is not palindromic, but occurs as tandem repeats as in higher eukaryotes.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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