Numbers of 5S and tRNA genes in macro- and micronuclei of Tetrahymena pyriformis - PubMed (original) (raw)

Numbers of 5S and tRNA genes in macro- and micronuclei of Tetrahymena pyriformis

A R Kimmel et al. Chromosoma. 1976.

Abstract

Macronuclei of Tetrahymena pyriformis contain approximately 200 copies of the genes for 25S and 17S ribosomal RNA (rRNA) per haploid genome. Micronuclei, however, contain only a few copies of the rRNA genes per haploid complement. Since macronuclei develop from products of meiosis, fertilization and division of micronuclei, we suggested that the multiple copies of the rRNA genes in macronuclei are generated by amplification of the small number of genes in micronuclei (Yao et al., 1974). This process provides a simple mechanism for maintaining the homogeneity of the repeated rRNA gnes. To test if amplification is a general mechanism operating on all repeated genes in Tetrahymena, we have examined the numbers of 5S RNA and tRNA genes in macro- and micronuclei. 5S RNA was purified by polyacrylamide gel electrophoresis and hybridized to saturation against macro- and micronuclear DNA. Approximately 0.013-0.014% of macronuclear DNA and about 0.009% of micronuclear DNA is complementary to 5S RNA. After correcting for the differences in the DNA sequence complexities between the two nuclei, we calculate that there are 300-350 5S genes per haploid macro- or micronuclear genome. From these data we conclude that there is little or no detectable amplification of the 5S genes in macronuclei relative to micronuclei. Similar studies using tRNA indicate that these genes are also highly repeated in both nuclei; about 800 genes are present per haploid genome. Thus, amplification from a small number of genes can be excluded as the mechanism for generating the repeated copies of the 5S and tRNA genes in Tetrahymena and it is likely that another, as yet unidentified, mechanism operates to maintain the homogeneity of these genes.

PubMed Disclaimer

Similar articles

• Organization of the 5S RNA genes in macro- and micronuclei of Tetrahymena pyriformis.
  Kimmel AR, Gorovsky MA. Kimmel AR, et al. Chromosoma. 1978 Jun 23;67(1):1-20. doi: 10.1007/BF00285644. Chromosoma. 1978. PMID: 99292
• A small number of cistrons for ribosomal RNA in the germinal nucleus of a eukaryote, Tetrahymena pyriformis.
  Yao MC, Kimmel AR, Gorovsky MA. Yao MC, et al. Proc Natl Acad Sci U S A. 1974 Aug;71(8):3082-6. doi: 10.1073/pnas.71.8.3082. Proc Natl Acad Sci U S A. 1974. PMID: 4606151 Free PMC article.
• Studies on the amount and location of the tRNA and 5-S rRNA genes in Tetrahymena pyriformis GL.
  Tonnesen T, Engberg J, Leick V. Tonnesen T, et al. Eur J Biochem. 1976 Apr 1;63(2):399-407. doi: 10.1111/j.1432-1033.1976.tb10241.x. Eur J Biochem. 1976. PMID: 816653
• Macro- and micronuclei of Tetrahymena pyriformis: a model system for studying the structure and function of eukaryotic nuclei.
  Gorovsky MA. Gorovsky MA. J Protozool. 1973 Feb;20(1):19-25. doi: 10.1111/j.1550-7408.1973.tb05995.x. J Protozool. 1973. PMID: 4632259 Review. No abstract available.
• Nucleic acids of Entamoeba histolytica.
  Albach RA. Albach RA. J Protozool. 1989 Mar-Apr;36(2):197-205. doi: 10.1111/j.1550-7408.1989.tb01074.x. J Protozool. 1989. PMID: 2470900 Review.

Cited by

• Organization of the 5S RNA genes in macro- and micronuclei of Tetrahymena pyriformis.
  Kimmel AR, Gorovsky MA. Kimmel AR, et al. Chromosoma. 1978 Jun 23;67(1):1-20. doi: 10.1007/BF00285644. Chromosoma. 1978. PMID: 99292
• Sequence organization within and flanking clusters of 5S ribosomal RNA genes in Tetrahymena.
  Pederson DS, Yao MC, Kimmel AR, Gorovsky MA. Pederson DS, et al. Nucleic Acids Res. 1984 Mar 26;12(6):3003-21. doi: 10.1093/nar/12.6.3003. Nucleic Acids Res. 1984. PMID: 6324137 Free PMC article.
• The tRNATyr-isoacceptors and their genes in the ciliate Tetrahymena thermophila: cytoplasmic tRNATyr has a QPsiA anticodon and is coded by multiple intron-containing genes.
  Junker V, Teichmann T, Hekele A, Fingerhut C, Beier H. Junker V, et al. Nucleic Acids Res. 1997 Nov 1;25(21):4194-200. doi: 10.1093/nar/25.21.4194. Nucleic Acids Res. 1997. PMID: 9336446 Free PMC article.
• The 5S ribosomal RNA gene clusters in Tetrahymena thermophila: strain differences, chromosomal localization, and loss during micronuclear ageing.
  Allen SL, Ervin PR, McLaren NC, Brand RE. Allen SL, et al. Mol Gen Genet. 1984;197(2):244-53. doi: 10.1007/BF00330970. Mol Gen Genet. 1984. PMID: 6596476
• A family of DNA sequences is reproducibly rearranged in the somatic nucleus of Tetrahymena.
  Allitto BA, Karrer KM. Allitto BA, et al. Nucleic Acids Res. 1986 Oct 24;14(20):8007-25. doi: 10.1093/nar/14.20.8007. Nucleic Acids Res. 1986. PMID: 2877440 Free PMC article.

References

1. 1. J Biol Chem. 1973 Nov 10;248(21):7530-9 - PubMed
2. 1. Biochim Biophys Acta. 1974 Oct 11;366(2):215-23 - PubMed
3. 1. J Mol Biol. 1972 Oct 14;70(3):637-49 - PubMed
4. 1. J Mol Biol. 1973 Aug 15;78(3):397-415 - PubMed
5. 1. Biochem Biophys Res Commun. 1974 Aug 19;59(4):1356-65 - PubMed

Publication types

MeSH terms

Substances