Abstract
Most cells of the male PTK2 cell line contain one nucleolus, and they are diploid. However, a proportion of cells have more than one nucleolus. Cells with two and three nucleoli were isolated and cloned into viable populations. Greater than 90% of the cells in these clonal populations maintained the abnormal nucleolar number of the originally isolated cell. Karyotype analysis of cells with two and three nucleoli demonstrated that the cells were respectively tetraploid and hexaploid. It was concluded that in PTK2 cells, nucleolarity is a good index of ploidy even if the ploidy level is abnormal. Furthermore, long term monitoring of the tetraploid cells demonstrated virtually no tendency towards reversion to the diploid condition as suggested by other studies in Potorous.
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Alvarez-Lomeli, B.: Algunas relaciones nucleo-nucleolares en células Hela. Bol. Inst. Estud. méd. biol. 21, 15–23 (1963)
Avanzi, S., Durante, M., Cionini, P.G., D'Amato, F.: Cytological localization of ribosomal cistrons in polytene chromosomes of Phaseolus coccineus. Chromosoma (Berl.) 39, 191–203 (1972)
Berns, M.W.: Laser microirradiation of chromosomes. Cold Spr. Harb. Symp. quant. Biol. 38, 165–174 (1974)
Berns, M.W., Floyd, A.D., Adkisson, K., Cheng, W.K., Moore, L., Hoover, G., Ustick, K., Burgott, S., Osial, T.: Laser microirradiation of the nucleolar organizer in cells of the rat kangaroo (Potorous tridactylis). Exp. Cell Res. 75, 424–432 (1972)
Brady, T., Clutter, M.E.: Cytolocalization of ribosomal cistrons in plant polytene chromosomes. J. Cell Biol. 53, 827–832 (1972)
Brown, D.D., Blackler, A.W.: Gene amplification proceeds by a chromosome copy mechanism. J. molec. Biol. 63, 75–84 (1972)
Brown, D.D., Gurdon, J.: Absence of ribosomal RNA synthesis in the anucleolate mutant of Xenopus laevis. Proc. nat. Acad. Sci. (Wash.) 51, 139–146 (1964)
Gerbi, S.: Localization and characterization of the ribosomal RNA cistrons in Sciara coprophila. J. molec. Biol. 58, 199–211 (1971)
Gonzalez, P., Nardone, R.: Cyclic nucleolar changes during the cell cycle. Exp. Cell Res. 50, 599–615 (1968)
Macgregor, H.C., Kezer, J.: The nucleolar organizer of Plethodon cinereus cinereus (Green). I. Location of the nucleolar organizer by in situ nucleic acid hybridization. Chromosoma (Berl.) 42, 415–426 (1973)
Martin, G., Sprague, C.: Parasexual cycle in cultivated human somatic cells. Science 166, 761–763 (1969)
Miller, L., Knowland, J.: The number and activity of ribosomal RNA genes in Xenopus laevis embryos carrying partial deletions in both nucleolar organizers. Biochem. Genet. 6, 65–73 (1972)
Ohnuki, Y., Olson, R.S., Rounds, D.E.: Modification of nucleolar formation in Pt-K2 rat-kangaroo cells by laser microbeam irradiation. Jap. J. Genet. 50, 67–72 (1975)
Pardue, M.L., Hsu, T.C.: Locations of 18S and 28S ribosomal genes on the chromosomes of the Indian muntjac. J. Cell Biol. 64, 251–254 (1975)
Phillips, S.G., Phillips, D.M.: Sites of nucleolus production in cultured Chinese hamster cells. J. Cell Biol. 40, 248–268 (1969)
Prescott, D.M., Bender, M.A.: Preparation of mammalian metaphase chromosomes for autoradiography. In: Methods in cell physiology, vol. I (D.M. Prescott, ed.), p. 382. New York: Academic Press Inc. 1964
Shaw, M.W., Krooth, R.S.: The chromosomes of the Tasmanian rat-kangaroo (Potorous tridactylis apicalis). Cytogenetics 3, 19–33 (1964)
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Branch, A.D., Berns, M.W. Nucleoli and ploidy in Potorous cells (PTK2) in vitro. Chromosoma 56, 33–40 (1976). https://doi.org/10.1007/BF00293727
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DOI: https://doi.org/10.1007/BF00293727