Abstract
The temporal schedule of DNA replication in heat-synchronized Tetrahymena was studied by autoradiographic and cytofluorometric methods. It was shown that some cells, which were synchronized by selection of individual dividing cells or by temporary thymidine starvation, incorporated [3H]thymidine into macronuclei in a periodic fashion during the heat-shock treatment. It was concluded that supernumerary S periods occurred while cell division was blocked by high temperature. The proportion of cells which initiated supernumerary S periods was found to be dependent on the duration of the heat-shock treatment and on the cell cycle stage when the first heat shock was applied. Cytofluorometric measurements of Feulgen-stained macronuclei during the heat-shock treatment indicated that the DNA complement of these cells was substantially increased and probably duplicated during the course of each S period. Estimates of DNA content also suggested that the rate of DNA synthesis progressively declined during long heat-shock treatments. These results indicate that the mechanism which brings about heat-induced division synchrony is not an interruption of the process of DNA replication. Further experiments were concerned with the regulation of DNA synthesis during the first synchronized division cycle. It was shown that participation in DNA synthesis at this time increased as more cells were able to conclude the terminal S period during the preceding heat-shock treatment. It is suggested that a discrete period of time is necessary after the completion of DNA synthesis before another round of DNA synthesis can be initiated.
Full Text
The Full Text of this article is available as a PDF (790.1 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Andersen H. A., Brunk C. F., Zeuthen E. Studies on the DNA replication in heat synchronized Tetrahymena pyriformis. C R Trav Lab Carlsberg. 1970;38(7):123–131. [PubMed] [Google Scholar]
- Byfield J. E., Lee Y. C. The effect of synchronizing temperature shifts on the synthesis and translation of replication-supporting messengers in Tetrahymena pyriformis. Exp Cell Res. 1970 Jul;61(1):42–50. doi: 10.1016/0014-4827(70)90255-7. [DOI] [PubMed] [Google Scholar]
- Byfield J. E., Scherbaum O. H. Incomplete inhibition of synchronized cell division by hydroxyurea and its relevance to the normal cellular life cycle. Nature. 1967 Dec 9;216(5119):1017–1018. doi: 10.1038/2161017a0. [DOI] [PubMed] [Google Scholar]
- Böhm N., Sprenger E. Fluorescence cytophotometry: a valuable method for the quantitative determination of nuclear Feulgen-DNA. Histochemie. 1968;16(2):100–118. doi: 10.1007/BF00280607. [DOI] [PubMed] [Google Scholar]
- CERRONI R. E., ZEUTHEN E. Asynchrony of nuclear incorporation of tritiated thymidine into Tetrahymena cells synchronized for division. C R Trav Lab Carlsberg. 1962;32:499–511. [PubMed] [Google Scholar]
- Charret R. L'ADN nucléolaire chez Tetrahymena pyriformis: chronoloe de sa réplication. Exp Cell Res. 1969 Mar;54(3):353–361. doi: 10.1016/0014-4827(69)90214-6. [DOI] [PubMed] [Google Scholar]
- Cleffmann G. Bildung zusätzlicher DNS nach Blockierung der Zellteilung von Tetrahymena durch Actinomycin. Z Zellforsch Mikrosk Anat. 1966;70(3):290–297. [PubMed] [Google Scholar]
- Cleffmann G. Regulierung der DNS-Menge im Makronucleus von Tetrahymena. Exp Cell Res. 1968 Apr;50(1):193–207. doi: 10.1016/0014-4827(68)90407-2. [DOI] [PubMed] [Google Scholar]
- ELFTMAN H. A Schiff reagent of calibrated sensitivity. J Histochem Cytochem. 1959 Mar;7(2):93–97. doi: 10.1177/7.2.93. [DOI] [PubMed] [Google Scholar]
- FRANKEL J. MORPHOGENESIS AND DIVISION IN CHAINS OF TETRAHYMENA PYRIFORMIS GL. J Protozool. 1964 Nov;11:514–526. doi: 10.1111/j.1550-7408.1964.tb01791.x. [DOI] [PubMed] [Google Scholar]
- Frankel J. The effect of nucleic acid antagonists on cell division and oral organelle development in Tetrahymena pyriformis. J Exp Zool. 1965 Jun;159(1):113–147. doi: 10.1002/jez.1401590109. [DOI] [PubMed] [Google Scholar]
- Hjelm K. K., Zeuthen E. Synchronous DNA synthesis following heat-synchronized cell division in Tetrahymena. Exp Cell Res. 1967 Oct;48(1):231–232. doi: 10.1016/0014-4827(67)90311-4. [DOI] [PubMed] [Google Scholar]
- Hjelm K. K., Zeuthen E. Synchronous DNA-synthesis induced by synchronous cell division in Tetrahymena. C R Trav Lab Carlsberg. 1967;36(8):127–160. [PubMed] [Google Scholar]
- IVERSON R. M., GIESE A. C. Nucleic acid content and ultraviolet susceptibility of Tetrahymena pyriformis. Exp Cell Res. 1957 Oct;13(2):213–223. doi: 10.1016/0014-4827(57)90001-0. [DOI] [PubMed] [Google Scholar]
- Jauker F., Cleffmann G. Oscillation of individual generation times in cells lines of Tetrahymena pyriformis. Exp Cell Res. 1970 Oct;62(2):477–480. doi: 10.1016/0014-4827(70)90582-3. [DOI] [PubMed] [Google Scholar]
- Jeffery W. R. Evidence for a temporal incompatibility between DNA replication and division during the cell cycle of Tetrahymena. J Cell Biol. 1972 Jun;53(3):624–634. doi: 10.1083/jcb.53.3.624. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jeffery W. R., Stuart K. D., Frankel J. The relationship between deoxyribonucleic acid replication and cell division in heat-synchronized tetrahymena. J Cell Biol. 1970 Sep;46(3):533–543. doi: 10.1083/jcb.46.3.533. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lee Y. C., Scherbaum O. H. Nucleohistone composition in stationary and division synchronized Tetrahymena cultures. Biochemistry. 1966 Jun;5(6):2067–2075. doi: 10.1021/bi00870a039. [DOI] [PubMed] [Google Scholar]
- Lowy B. A., Leick V. The synthesis of DNA in synchronized cultures of Tetrahymena pyriformis GL. Exp Cell Res. 1969 Oct;57(2):277–288. doi: 10.1016/0014-4827(69)90151-7. [DOI] [PubMed] [Google Scholar]
- PRESCOTT D. M. Change in the physiological state of a cell population as a function of culture growth and age (Tetrahymena geleit). Exp Cell Res. 1957 Feb;12(1):126–134. doi: 10.1016/0014-4827(57)90300-2. [DOI] [PubMed] [Google Scholar]
- PRESCOTT D. M. Variations in the individual generation times of Tetrahymena geleii HS. Exp Cell Res. 1959 Feb;16(2):279–284. doi: 10.1016/0014-4827(59)90255-1. [DOI] [PubMed] [Google Scholar]
- SCHERBAUM O. H., LOUDERBACK A. L., JAHN T. L. DNA synthesis, phosphate content and growth in mass and volume in synchronously dividing cells. Exp Cell Res. 1959 Aug;18:150–166. doi: 10.1016/0014-4827(59)90298-8. [DOI] [PubMed] [Google Scholar]
- SCHERBAUM O. The content and composition of nucleic acids in normal and synchronously dividing mass cultures of Tetrahymena pyriformis. Exp Cell Res. 1957 Aug;13(1):24–30. doi: 10.1016/0014-4827(57)90040-x. [DOI] [PubMed] [Google Scholar]
- SCHERBAUM O., ZEUTHEN E. Induction of synchronous cell division in mass cultures of Tetrahymena piriformis. Exp Cell Res. 1954 Feb;6(1):221–227. doi: 10.1016/0014-4827(54)90164-0. [DOI] [PubMed] [Google Scholar]
- THORMAR H. Delayed division in tetrahymena pyriformis induced by temperature changes. C R Trav Lab Carlsberg. 1959;31:207–225. [PubMed] [Google Scholar]
- Villadsen I. S., Zeuthen E. Synchronization of DNA synthesis in Tetrahymena populations by temporary limitation of access to thymine compounds. Exp Cell Res. 1970 Aug;61(2):302–310. doi: 10.1016/0014-4827(70)90452-0. [DOI] [PubMed] [Google Scholar]
- Zeuthen E. Independent synchronization of DNA synthesis and of cell division in same culture of Tetrahymena cells. Demonstration that heat-shock induced division-synchrony is by differential extension of the G2 phase. Exp Cell Res. 1970 Aug;61(2):311–325. doi: 10.1016/0014-4827(70)90453-2. [DOI] [PubMed] [Google Scholar]
- Zeuthen E. Thymine starvation by inhibition of uptake and synthesis of thymine-compounds in Tetrahymena. Exp Cell Res. 1968 Apr;50(1):37–46. doi: 10.1016/0014-4827(68)90391-1. [DOI] [PubMed] [Google Scholar]
