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. 1988 Sep;120(1):123–134. doi: 10.1093/genetics/120.1.123

Organization of the Micronuclear Genome of Oxytricha Nova

C L Jahn 1, K E Prescott 1, M W Waggener 1
PMCID: PMC1203484  PMID: 17246474

Abstract

In the hypotrichous ciliated protozoan Oxytricha nova, approximately 95% of the micronuclear genome, including all of the repetitive DNA and most of the unique sequence DNA, is eliminated during the formation of the macronuclear genome. We have examined the interspersion patterns of repetitive and unique and eliminated and retained sequences in the micronuclear genome by characterizing randomly selected clones of micronuclear DNA. Three major classes of clones have been defined: (1) those containing primarily unique, retained sequences; (2) those containing only unique, eliminated sequences; and (3) those containing only repetitive, eliminated sequences. Clones of type one and three document two aspects of organization observed previously: clustering of macronuclear destined sequences and the presence of a prevalent repetitive element. Clones of the second type demonstrate for the first time that eliminated unique sequence DNA occurs in long stretches uninterrupted by repetitive sequences. To further examine repetitive sequence interspersion, we characterized the repetitive sequence family that is present in 50% of the clones (class three above). A consensus map of this element was obtained by mapping approximately 80 phage clones and by hybridization to digests of micronuclear DNA. The repeat element is extremely large (approximately 24 kb) and is interspersed with both macronuclear destined sequences and eliminated unique sequences.

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Selected References

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

  1. Altschuler M. I., Yao M. C. Macronuclear DNA of Tetrahymena thermophila exists as defined subchromosomal-sized molecules. Nucleic Acids Res. 1985 Aug 26;13(16):5817–5831. doi: 10.1093/nar/13.16.5817. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Austerberry C. F., Yao M. C. Nucleotide sequence structure and consistency of a developmentally regulated DNA deletion in Tetrahymena thermophila. Mol Cell Biol. 1987 Jan;7(1):435–443. doi: 10.1128/mcb.7.1.435. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Cartinhour S. W., Herrick G. A. Three different macronuclear DNAs in Oxytricha fallax share a common sequence block. Mol Cell Biol. 1984 May;4(5):931–938. doi: 10.1128/mcb.4.5.931. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Conover R. K., Brunk C. F. Macronuclear DNA molecules of Tetrahymena thermophila. Mol Cell Biol. 1986 Mar;6(3):900–905. doi: 10.1128/mcb.6.3.900. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Dawson D., Herrick G. Telomeric properties of C4A4-homologous sequences in micronuclear DNA of Oxytricha fallax. Cell. 1984 Jan;36(1):171–177. doi: 10.1016/0092-8674(84)90086-2. [DOI] [PubMed] [Google Scholar]
  6. Feinberg A. P., Vogelstein B. A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity. Anal Biochem. 1983 Jul 1;132(1):6–13. doi: 10.1016/0003-2697(83)90418-9. [DOI] [PubMed] [Google Scholar]
  7. Frischauf A. M., Lehrach H., Poustka A., Murray N. Lambda replacement vectors carrying polylinker sequences. J Mol Biol. 1983 Nov 15;170(4):827–842. doi: 10.1016/s0022-2836(83)80190-9. [DOI] [PubMed] [Google Scholar]
  8. Helftenbein E. Nucleotide sequence of a macronuclear DNA molecule coding for alpha-tubulin from the ciliate Stylonychia lemnae. Special codon usage: TAA is not a translation termination codon. Nucleic Acids Res. 1985 Jan 25;13(2):415–433. doi: 10.1093/nar/13.2.415. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Herrick G., Cartinhour S., Dawson D., Ang D., Sheets R., Lee A., Williams K. Mobile elements bounded by C4A4 telomeric repeats in Oxytricha fallax. Cell. 1985 Dec;43(3 Pt 2):759–768. doi: 10.1016/0092-8674(85)90249-1. [DOI] [PubMed] [Google Scholar]
  10. Herrick G., Hunter D., Williams K., Kotter K. Alternative processing during development of a macronuclear chromosome family in Oxytricha fallax. Genes Dev. 1987 Dec;1(10):1047–1058. doi: 10.1101/gad.1.10.1047. [DOI] [PubMed] [Google Scholar]
  11. Howard E. A., Blackburn E. H. Reproducible and variable genomic rearrangements occur in the developing somatic nucleus of the ciliate Tetrahymena thermophila. Mol Cell Biol. 1985 Aug;5(8):2039–2050. doi: 10.1128/mcb.5.8.2039. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Karrer K. M. Germ line-specific DNA sequences are present on all five micronuclear chromosomes in Tetrahymena thermophila. Mol Cell Biol. 1983 Nov;3(11):1909–1919. doi: 10.1128/mcb.3.11.1909. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Klobutcher L. A., Vailonis-Walsh A. M., Cahill K., Ribas-Aparicio R. M. Gene-sized macronuclear DNA molecules are clustered in micronuclear chromosomes of the ciliate Oxytricha nova. Mol Cell Biol. 1986 Nov;6(11):3606–3613. doi: 10.1128/mcb.6.11.3606. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Lauth M. R., Spear B. B., Heumann J., Prescott D. M. DNA of ciliated protozoa: DNA sequence diminution during macronuclear development of Oxytricha. Cell. 1976 Jan;7(1):67–74. doi: 10.1016/0092-8674(76)90256-7. [DOI] [PubMed] [Google Scholar]
  15. Moritz K. B., Roth G. E. Complexity of germline and somatic DNA in Ascaris. Nature. 1976 Jan 1;259(5538):55–57. doi: 10.1038/259055a0. [DOI] [PubMed] [Google Scholar]
  16. Orgel L. E., Crick F. H. Selfish DNA: the ultimate parasite. Nature. 1980 Apr 17;284(5757):604–607. doi: 10.1038/284604a0. [DOI] [PubMed] [Google Scholar]
  17. Prescott D. M., Murti K. G. Chromosome structure in ciliated protozoans. Cold Spring Harb Symp Quant Biol. 1974;38:609–618. doi: 10.1101/sqb.1974.038.01.065. [DOI] [PubMed] [Google Scholar]
  18. Pruitt R. E., Meyerowitz E. M. Characterization of the genome of Arabidopsis thaliana. J Mol Biol. 1986 Jan 20;187(2):169–183. doi: 10.1016/0022-2836(86)90226-3. [DOI] [PubMed] [Google Scholar]
  19. Ribas-Aparicio R. M., Sparkowski J. J., Proulx A. E., Mitchell J. D., Klobutcher L. A. Nucleic acid splicing events occur frequently during macronuclear development in the protozoan Oxytricha nova and involve the elimination of unique DNA. Genes Dev. 1987 Jun;1(4):323–336. doi: 10.1101/gad.1.4.323. [DOI] [PubMed] [Google Scholar]
  20. Swanton M. T., Greslin A. F., Prescott D. M. Arrangement of coding and non-coding sequences in the DNA molecules coding for rRNAs in Oxytricha sp. DNA of ciliated protozoa. VII. Chromosoma. 1980;77(2):203–215. doi: 10.1007/BF00329545. [DOI] [PubMed] [Google Scholar]
  21. Swanton M. T., Heumann J. M., Prescott D. M. Gene-sized DNA molecules of the macronuclei in three species of hypotrichs: size distributions and absence of nicks. DNA of ciliated protozoa. VIII. Chromosoma. 1980;77(2):217–227. doi: 10.1007/BF00329546. [DOI] [PubMed] [Google Scholar]
  22. Yao M. C., Choi J., Yokoyama S., Austerberry C. F., Yao C. H. DNA elimination in Tetrahymena: a developmental process involving extensive breakage and rejoining of DNA at defined sites. Cell. 1984 Feb;36(2):433–440. doi: 10.1016/0092-8674(84)90236-8. [DOI] [PubMed] [Google Scholar]
  23. Yao M. C., Gorovsky M. A. Comparison of the sequences of macro- and micronuclear DNA of Tetrahymena pyriformis. Chromosoma. 1974;48(1):1–18. doi: 10.1007/BF00284863. [DOI] [PubMed] [Google Scholar]

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