Abstract
Macro- and micronuclei were isolated from Tetrahymena pyriformis (Syngen 1, strain WH-6) and their DNAs compared by isopycnic centrifugation in neutral and alkaline CsCl, by analysis of thermal denaturation properties and by molecular hybridization. Unlike the situation observed in Stylonychia the buoyant densities and thermal denaturation patterns of Tetrahymena macro- and micronuclear DNAs were virtually identical—the only observable differences bordering on the limits of resolution of these techniques. DNA was isolated from the two nuclei which had been labelled with different radioactive isotopes (i.e. 14C-thymidine and 3H-thymidine), and the renaturation kinetics of mixtures of macro- and micronuclear DNA were examined using a single-strand specific deoxyribonuclease (S1). Renaturation kinetics obtained using varying ratios of macro- and micronuclear DNA suggested that 80–90% of the sequences present in micronuclei were present in similar amounts in macronuclei. However, careful analyses of the renaturation kinetics indicate that approximately 10–20% of the sequences found in micronuclei are probably absent in macronuclei, and that most of these sequences are probably moderately repetitive (100 copies per genome or less). These findings place severe constraint on possible models concerning the structure of the Tetrahymena macronucleus, and are very different from the situation observed in Stylonychia where it has been suggested that only a small percentage of the sequences in micronuclei are present in significant amounts in macronuclei. Nonetheless, these results along with those in Stylonychia can be taken as an indication that the loss or under-replication of some DNA sequences accompanies macronuclear differentiation in ciliates.
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References
Allen, S., Gibson, I.: Genetics of Tetrahymena. In: Biology of Tetrahymena (A. M., Elliott, ed.), pp. 307–373. Stroudsburg: Dowden, Hutchinson and Ross. Inc. 1973
Ammermann, D., Steinbrück, G., Bergen, L., Hennig, W.: The development of the macronucleus in the ciliated protozoan Stylonychia mytilus. Chromosoma (Berl.) 45, 401–429 (1974)
Britten, J. R., Kohne, D. E.: Repeated sequences in DNA. Science 161, 529–540 (1968)
Brown, D. D., Dawid, I. B.: Specific gene amplification of oocytes. Science 160, 272–280 (1968)
Davidson, E. H., Hough, B. R., Amenson, C. S., Britten, A. J.: General interspersion of repetitive with non-repetitive sequence elements in the DNA of Xenopus. J. molec. Biol. 77, 1–23 (1973)
Elliott, A. M., Hayes, R. E.: Mating types in Tetrahymena. Biol. Bull. 105, 269–284 (1953)
Engberg, J., Nilsson, J. R., Pearlman, R. E., Leick, V.: Induction of nuclear and mitochondrial DNA replication in Tetrahymena pyriformis. Proc. nat. Acad. Sci. (Wash.) 71, 895–898 (1974)
Engberg, J., Pearlman, R. E.: The amount of ribosomal RNA genes in Tetrahymena pyriformis in different physiological states. Europ. J. Biochem. 26, 393–400 (1972)
Gall, J. G.: Differential synthesis of the genes for ribosomal RNA during oogenesis. Proc. nat. Acad. Sci. (Wash.) 60, 553–560 (1968)
Gall, J. G.: Free ribosomal RNA genes in the macronucleus of Tetrahymena. Proc. nat. Acad. Sci. (Wash.) (in press, 1974)
Gall, J. G., Cohen, E. H., Polan, M. L.: Repetitive DNA sequences in Drosophila. Chromosoma (Berl.) 33, 319–344 (1971)
Gorovsky, M. A.: Studies on nuclear structure and function in Tetrahymena pyriformis II. Isolation of Macro- and Mieronuclei. J. Cell Biol. 47, 619–630 (1970)
Gorovsky, M. A.: Macro- and micronuclei of Tetrahymena pyriformis: a model system for studying the structure and function of eukaryotic nuclei. J. Protozool. 20, 19–25 (1973)
Gorovsky, M. A., Hattman, S., Pleger, G. L.: 6N-methyl adenine in the nuclear DNA of a eukaryote, Tetrahymena pyriformis. J. Cell Biol. 56, 697–701 (1973)
Gorovsky, M. A., Yao, M.-C., Keevert, J. B., Pleger, G. L.: Isolation of micro- and macronuclei of Tetrahymena pyriformis. Methods in Cell Biol. (in press, 1974)
Marmur, J., Doty, P.: Determination of the base composition of deoxyribonueleic acid from its thermal denaturation temperature. J. molec. Biol. 5, 109–118 (1962)
McDonald, B. B.: Nucleic acids in Tetrahymena during vegetative growth and and conjugation. In: Biology of Tetrahymena (A. M. Elliott, ed.), pp. 287–306. Stroudsburg: Dowden, Hutchinson and Ross, Inc. 1973
Nanney, D. L.: Macronuclear differentiation and subnuclear assortment in ciliates. Symp. Soc, Study Develop. Growth 23, 253–273 (1964)
Prescott, D. M., Murti, K. G., Bostock, C. J.: Genetic apparatus of Stylonychia sp. Nature (Lond.) 242, 576–600 (1973)
Ray, C., Jr.: Meiosis and nuclear behavior in Tetrahymena pyriformis. J. Protozool. 3, 88–96 (1956)
Schensted, I. V.: Model of subnuclear segregation in the macronucleus of ciliates. Amer. Naturalist 92, 161–170 (1958)
Schildkraut, C. L., Marmur, J., Doty, P.: Determination of base composition of deoxyribonueleic acid from its buoyant density in CsCl. J. molec. Biol. 4, 430–443 (1962)
Tobler, H., Smith, K. D., Ursprung, H.: Molecular aspects of chromatin elimination in Ascaris lumbricoides. Develop. Biol. 27, 190–203 (1972)
Vogt, V. M.: Purification and further properties of single-strand-specific nuclease from Aspergillus oryzae. Europ. J. Biochem. 33, 192–200 (1973)
Woese, C. R., Bleyman, M. A.: Genetic code limit organisms—do they exist? J. molec. Evolution 1, 223–229 (1972)
Woodard, J., Kaneshiro, E., Gorovsky, M. A.: Cytochemical studies on the problem of macronuclear subnuclei in Tetrahymena. Genetics 70, 251–260 (1972)
Yao, M.-C., Kimmel, A. R., Gorovsky, M. A.: A small number of cistrons for ribosomal RNA in the germinal nucleus of a eukaryote, Tetrahymena pyriformis. Proc. nat. Acad. Sci. (Wash.) (in press, 1974)
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Yao, MC., Gorovsky, M.A. Comparison of the sequences of macro- and micronuclear DNA of Tetrahymena pyriformis . Chromosoma 48, 1–18 (1974). https://doi.org/10.1007/BF00284863
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DOI: https://doi.org/10.1007/BF00284863