Abstract
Chromatin organization and transcriptional activity in the macronucleus of the ciliate Paramecium primaurelia have been studied by electron microscopic examination of spread chromatin preparations. Under spreading conditions which inhibit the activity of endogenous nucleases and proteases, various morphologically distinct types of chromatin are seen: (1) Largely condensed chromatin in the form of 30–40 nm supranucleosomal globules which aggregate to form knobbly 40–60 nm fibres and unravel into 12 nm nucleosomal filaments; (2) In rapidly growing cells, extended chromatin arranged as groups of 4–8 adjacent nucleofilaments, each bearing numerous and very densely packed lateral fibrils. These fibrils are 20 nm thick, have a smooth outline and extend to lengths of up to 3 μm. Such transcripts are grouped in units along the chromatin axis and are apparently organized in register in adjacent filaments; (3) In starved cells, extended nucleofilaments bearing only occasional RNP fibrils. These various morphological characteristics are discussed in terms of macronuclear transcriptional activity and the polyploid nature of macronuclei.
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References
Ammermann, D., Steinbrück, G., Berger, L. von, Hennig, W.: The development of the macronucleus in the ciliated protozoan Stylonychia mytilus. Chromosoma (Berl.) 45, 401–429 (1974)
Berezney, R.: The nuclear protein matrix. In: The cell nucleus (H. Busch, ed.), vol. 8, pp. 413–455. New York, London: Academic Press 1979
Cummings, D.J.: Studies on macronuclear DNA from Paramecium aurelia. Chromosoma (Berl.) 53, 191–208 (1975)
Cummings, D.J., Tait, A.: The isolation of nuclei from Paramecium aurelia. IN: Methods in cell biology (D.M. Prescott, ed.), vol. 9, pp. 281–309. New York, London: Academic Press 1975
Findly, R.C., Gall, J.G.: Free ribosomal genes in Paramecium are tandemly repeated. Proc. nat. Acad. Sci. (Wash.) 75, 3312–3316 (1978)
Glätzer, K.H.: Regular substructure within homologous transcripts of spread Drosophila germ cells. Exp. Cell Res. 125, 519–523 (1980)
Gorovsky, M.A., Glover, C., Johmann, C.A., Keevert, J.B., Mathis, D.J., Samuelson, M.: Histones and chromatin structure in Tetrahymena macro- and micronuclei. Cold Spr. Harb. Symp. quant. Biol. 42, 493–503 (1978)
Grell, K.G.: The protozoan nucleus. In: The cell (J. Brachet and A. Mirsky, eds.), vol. 6, pp. 1–79. New York, London: Academic Press 1964
Hozier, J., Renz, M., Nehls, P.: The chromosome fibre: evidence for an ordered superstructure of nucleosomes. Chromosoma (Berl.) 61, 301–317 (1977)
Johmann, C.A., Gorovsky, M.A.: Purification and characterization of the histones associated with the macronucleus of Tetrahymena. Biochemistry 15, 1249–1256 (1976)
Jurand, A., Beale, G.H., Young, M.R.: Studies on the macronucleus of Paramecium aurelia I. With a note on ultraviolet micrography. J. Protozool. 9, 122–131 (1962)
Kosciusko, H.: Karyologic and genetic investigation of syngen 1 of Paramecium aurelia. Folia Biol. (Cracow) 13, 339–368 (1965)
Laird, D.D., Wilkinson, L.E., Foe, V.E., Chooi, W.Y.: Analysis of chromatin-associated fiber arrays. Chromosoma (Berl.) 56, 169–190 (1976)
Lipps, H.J., Hantke, K.G.: Studies on the histones of the ciliate Stylonychia mytilus. Chromosoma (Berl.) 49, 309–320 (1975)
Lipps, H.J., Morris, N.R.: Chromatin structure in the nuclei of the ciliate Stylonychia mytilus. Biochem. biophys. Res. Commun. 74, 230–234 (1977)
Lipps, H.J., Sapra, G.R., Ammermann, D.: The histones of the ciliated protozoan Stylonychia mytilus. Chromosoma (Berl.) 45, 273–280 (1974)
Lipps, H.J., Nock, A., Riewe, M., Steinbruck, G.: Chromatin structure of the macronucleus of Stylonychia mytilus. Nucleic Acids Res. 5, 4699–4709 (1978)
McTavish, C., Sommerville, J.: Macronuclear DNA organization and transcription in Paramecium primaurelia. Chromosoma (Berl.) 78, 147–164 (1980)
Meyer, G.F., Lipps, H.J.: Chromatin elimination in the hypotrichous ciliate Stylonychia mytilus. Chromosoma (Berl.) 77, 285–297 (1980)
Miller, O.L., Bakken, A.H.: Morphological studies of transcription. Acta endocr. (Copenh.) Suppl. 168, 155–177 (1972)
Miller, O.L., Beatty, B.R.: Visualization of nucleolar genes. Science 164, 955–957 (1969)
Olins, A.L., Olins, D.E.: Spheroid chromatin units (v-bodies). Science 183, 330–332 (1974)
Raikov, I.B.: The macronucleus of ciliates. In: Research in Protozoology (T.-T. Chen ed.), vol. 3, pp. 1–128. Oxford: Pergamon Press 1969
Raikov, I.B.: Evolution of macronuclear organization. Ann. Rev. Genet. 10, 413–440 (1976)
Renz, M., Nehls, P., Hozier, J.: Involvement of histone H1 in the organization of the chromosome fiber. Proc. nat. Acad. Sci. (Wash.) 74, 1879–1883 (1977)
Scheer, U.: Changes of nucleosome frequency in nucleolar and non-nucleolar chromatin as a function of transcription: an electron microscopic study. Cell 13, 535–549 (1978)
Scheer, U., Sommerville, J., Bustin, M.: Injected histone antibodies interfere with transcription of lampbrush chromosome loops in oocytes of Pleurodeles. J. Cell Sci. 40, 1–20 (1979)
Scheer, U., Sommerville, J., Müller, U.: DNA is assembled into globular supranucleosomal chromatin structures by nuclear contents of amphibian oocytes. Exp. Cell Res. 129, 115–126 (1980)
Sommerville, J.: Immunolocalization and structural organization of nascent RNP. In: The cell nucleus (H. Busch, ed.), vol. 8, pp. 1–57. New York, London: Academic Press 1981
Sonneborn, T.M.: Recent advances in the genetics of Paramecium and Euplotes. Advanc. in Genet. 1, 263–358 (1947)
Strätling, W.H., Müller, U., Zentgraf, H.: The higher order repeat structure of chromatin is built up of globular particles containing eight nucleosomes. Exp. Cell Res. 117, 301–311 (1978)
Wolfe, J.: Structural aspects of amitosis: A light and electron microscope study of the isolated macronuclei of Paramecium aurelia and Tetrahymena pyriformis. Chromosoma (Berl.) 23, 57–79 (1967)
Woodard, J., Woodard, M., Gelba, B., Swift, H.: Cytochemical studies on conjugation in Paramecium aurelia. Exp. Cell Res. 41, 55–63 (1966)
Wunderlich, F., Herlan, G.: A reversibly contractile nuclear matrix: its isolation, structure and composition. J. Cell Biol. 73, 271–278 (1977)
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Samuel, C., Mackie, J. & Sommerville, J. Macronuclear chromatin organization in Paramecium primaurelia . Chromosoma 83, 481–492 (1981). https://doi.org/10.1007/BF00328274
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DOI: https://doi.org/10.1007/BF00328274