Abstract
After conjugation between Chlamydomonas gametes of opposite mating type, a transient dikaryon is formed. The two nuclei fuse within 4-6 hr after mating. The young diploid zygote differentiates into dormant zygospore competent to complete meiosis, or more rarely (2-10% of cases) it undergoes mitosis to produce a stable diploid progeny. We here bring genetical, biochemical, and cytological evidence that among the mitotic zygotes, a large proportion of them undergo cytokinesis without fusion of the nuclei-a process that has been termed "cytoduction." By using appropriate genetic markers, haploid cytoductants that possess the nuclear genotype of one parent and the chloroplast marker of the other parent can easily be isolated. Genetical analysis and hybridization experiments moreover show that many haploid cytoductants transmit the chloroplast DNA molecules of both parents and that, as in diploids, these DNA copies occasionally recombine. This process of cytoduction extends the life cycle of Chlamydomonas and provides new tools for its genetic analysis.
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- Cavalier-Smith T. Electron microscopic evidence for chloroplast fusion in zygotes of Chlamydomonas reinhardii. Nature. 1970 Oct 24;228(5269):333–335. doi: 10.1038/228333a0. [DOI] [PubMed] [Google Scholar]
- Conde J., Fink G. R. A mutant of Saccharomyces cerevisiae defective for nuclear fusion. Proc Natl Acad Sci U S A. 1976 Oct;73(10):3651–3655. doi: 10.1073/pnas.73.10.3651. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dutcher S. K. Nuclear fusion-defective phenocopies in Chlamydomonas reinhardtii: mating-type functions for meiosis can act through the cytoplasm. Proc Natl Acad Sci U S A. 1988 Jun;85(11):3946–3950. doi: 10.1073/pnas.85.11.3946. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ebersold W. T. Chlamydomonas reinhardi: heterozygous diploid strains. Science. 1967 Jul 28;157(3787):447–449. doi: 10.1126/science.157.3787.447. [DOI] [PubMed] [Google Scholar]
- Harris E. H., Burkhart B. D., Gillham N. W., Boynton J. E. Antibiotic resistance mutations in the chloroplast 16S and 23S rRNA genes of Chlamydomonas reinhardtii: correlation of genetic and physical maps of the chloroplast genome. Genetics. 1989 Oct;123(2):281–292. doi: 10.1093/genetics/123.2.281. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kim J., Ljungdahl P. O., Fink G. R. kem mutations affect nuclear fusion in Saccharomyces cerevisiae. Genetics. 1990 Dec;126(4):799–812. doi: 10.1093/genetics/126.4.799. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kuroiwa T., Kawano S., Nishibayashi S., Sato C. Epifluorescent microscopic evidence for maternal inheritance of chloroplast DNA. Nature. 1982 Jul 29;298(5873):481–483. doi: 10.1038/298481a0. [DOI] [PubMed] [Google Scholar]
- Labarca C., Paigen K. A simple, rapid, and sensitive DNA assay procedure. Anal Biochem. 1980 Mar 1;102(2):344–352. doi: 10.1016/0003-2697(80)90165-7. [DOI] [PubMed] [Google Scholar]
- Matagne R. F., Hermesse M. P. Modification of Chloroplast Gene Transmission in Somatic Fusion Products and Vegetative Zygotes of CHLAMYDOMONAS REINHARDI by 5-Fluorodeoxyuridine. Genetics. 1981 Nov;99(3-4):371–381. doi: 10.1093/genetics/99.3-4.371. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Munaut C., Dombrowicz D., Matagne R. F. Detection of chloroplast DNA by using fluorescent monoclonal anti-bromodeoxyuridine antibody and analysis of its fate during zygote formation in Chlamydomonas reinhardtii. Curr Genet. 1990 Oct;18(3):259–263. doi: 10.1007/BF00318390. [DOI] [PubMed] [Google Scholar]
- Newman S. M., Boynton J. E., Gillham N. W., Randolph-Anderson B. L., Johnson A. M., Harris E. H. Transformation of chloroplast ribosomal RNA genes in Chlamydomonas: molecular and genetic characterization of integration events. Genetics. 1990 Dec;126(4):875–888. doi: 10.1093/genetics/126.4.875. [DOI] [PMC free article] [PubMed] [Google Scholar]