Abstract
In a generation time of 8 hr in Paramecium caudatum, the bulk of DNA synthesis detected by thymidine-3H incorporation takes place in the latter part of the cell cycle. The micronuclear cycle includes a G1 of 3 hr followed by an S period of 3–3½ hr. G2 and division occupies the remaining period of the cycle. Macronuclear RNA synthesis detected by 5'-uridine-3H incorporation is continuous throughout the cell cycle. Micronuclear RNA synthesis is restricted to the S period. Ribonuclease removes 80–90% of the incorporated label. Pulse-chase experiments showed that part of the RNA is conserved and released to the cytoplasm during the succeeding G1 period.
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Selected References
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- Chen T. T. Conjugation in Paramecium Bursaria between Animals with Very Different Chromosome Numbers and between Animals with and without Micronuclei. Proc Natl Acad Sci U S A. 1940 Apr 15;26(4):243–246. doi: 10.1073/pnas.26.4.243. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chen T. T. Evidences of Exchange of Pronuclei during Conjugation in Paramecium Bursaria. Proc Natl Acad Sci U S A. 1940 Apr 15;26(4):241–243. doi: 10.1073/pnas.26.4.241. [DOI] [PMC free article] [PubMed] [Google Scholar]
- KIMBALL R. F., BARKA T. Quantitative cytochemical studies on Paramecium aurelia. II. Feulgen microspectrophotometry of the macronucleus during exponential growth. Exp Cell Res. 1959 Apr;17(1):173–182. doi: 10.1016/0014-4827(59)90162-4. [DOI] [PubMed] [Google Scholar]
- KIMBALL R. F., PERDUE S. W. Quantitative cytochemical studies on Paramecium. V. Autoradiographic studies of nucleic acid syntheses. Exp Cell Res. 1962 Sep;27:405–415. doi: 10.1016/0014-4827(62)90005-8. [DOI] [PubMed] [Google Scholar]
- WALKER P. M., MITCHISON J. M. DNA synthesis in two ciliates. Exp Cell Res. 1957 Aug;13(1):167–170. doi: 10.1016/0014-4827(57)90060-5. [DOI] [PubMed] [Google Scholar]
- WOODARD J., GELBER B., SWIFT H. Nucleoprotein changes during the mitotic cycle in Paramecium aurelia. Exp Cell Res. 1961 Mar;23:258–264. doi: 10.1016/0014-4827(61)90036-2. [DOI] [PubMed] [Google Scholar]