Abstract
Conditional "cycle-blocked" (cb) mutants of Chlamydomonas reinhardtii have been detected and isolated. These mutants exhibit normal vegetative growth at permissive temperature but are unable to complete a cell cycle (or a specified number of cell cycles) at restrictive temperature. A simple technique has been devised to determine the cell cycle stage in each mutant when the defective gene product, which ultimately affects cell division, completes its function. This stage is called the "block point", and is determined by scoring the residual cell division in an exponentially growing population after shift to temperature restrictive conditions. In the cb mutants isolated so far, block points representing many stages throughout the cell cycle have been found. Two categories of cb mutants are described here: one set which prevents the subsequent cell division when the cell encounters the block point after a shift to restrictive temperature, and another set which permits an additional round of cell division after the block point is encountered. The general applicability of block point analysis to other cell systems is presented.
Full Text
The Full Text of this article is available as a PDF (807.8 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Armstrong J. J., Moll B., Surzycki S. J., Levine R. P. Genetic transcription and translation specifying chloroplast components in Chlamydomonas reinhardi. Biochemistry. 1971 Feb 16;10(4):692–701. doi: 10.1021/bi00780a022. [DOI] [PubMed] [Google Scholar]
- Chiang K. S., Sueoka N. Replication of chloroplast DNA in Chlamydomonas reinhardi during vegetative cell cycle: its mode and regulation. Proc Natl Acad Sci U S A. 1967 May;57(5):1506–1513. doi: 10.1073/pnas.57.5.1506. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hartwell L. H., Culotti J., Reid B. Genetic control of the cell-division cycle in yeast. I. Detection of mutants. Proc Natl Acad Sci U S A. 1970 Jun;66(2):352–359. doi: 10.1073/pnas.66.2.352. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hartwell L. H. Genetic control of the cell division cycle in yeast. II. Genes controlling DNA replication and its initiation. J Mol Biol. 1971 Jul 14;59(1):183–194. doi: 10.1016/0022-2836(71)90420-7. [DOI] [PubMed] [Google Scholar]
- Kates J. R., Jones R. F. Periodic increases in enzyme activity in synchronized cultures of Chlamydomonas reinhardtii. Biochim Biophys Acta. 1967 Aug 22;145(1):153–158. doi: 10.1016/0005-2787(67)90664-8. [DOI] [PubMed] [Google Scholar]
- Sueoka N., Chiang K. S., Kates J. R. Deoxyribonucleic acid replication in meiosis of Chlamydomonas reinhardi. I. Isotopic transfer experiments with a strain producing eight zoospores. J Mol Biol. 1967 Apr 14;25(1):47–66. doi: 10.1016/0022-2836(67)90278-1. [DOI] [PubMed] [Google Scholar]