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. 1988 Apr;8(4):1664–1669. doi: 10.1128/mcb.8.4.1664

Transformation of Tetrahymena thermophila with hypermethylated rRNA genes.

K M Karrer 1, M C Yao 1
PMCID: PMC363326  PMID: 3380092

Abstract

The extrachromosomal rRNA genes (rDNA) of Tetrahymena thermophila contain 0.4% N6-methyladenine. C3 strain rDNA was isolated, hypermethylated in vitro, and microinjected into B strain host cells. Clonal cell lines were established, and transformants were selected on the basis of resistance to paromomycin, conferred by the injected rDNA. The effects of methylation by three enzymes which methylate the sequence 5'-NAT-3', the dam, EcoRI, and ClaI methylases, were tested. Hypermethylation of the injected rDNA had no effect on transformation efficiency relative to mock-methylated controls. The injected C3 strain rDNA efficiently replaced host rDNA as the major constituent of the population of rDNA molecules. Hypermethylation of the injected DNA was not maintained through 20 to 25 cell generations.

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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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