Initiation of meiosis in cell cycle initiation mutants of Saccharomyces cerevisiae (original) (raw)
Related papers
Commitment to the mitotic cell cycle in yeast in relation to meiosis*1
Experimental Cell Research, 1977
Under restrictive vegetative conditions, cells of celldivision cycle (cdc) temperature-sensitive mutants arrest at specific points in the cycle. Meiotic and mitotic behaviour of such arrested cells was examined under permissive sporulation conditions. Those mutants which were committed to mitosis at their specific point of arrest finished the cell cycle and could only then go into meiosis. It was found that commitment to mitosis occurred early in the cell cycle, prior to DNA replication, and that this commitment was dependent upon the gene function of cdd.
Meiotic recombination and DNA synthesis in a new cell cycle mutant of Saccharomyces cerevisiae
Genetics, 1978
Vegetative cells carrying the new temperature-sensitive mutation cdc40 arrest at the restrictive temperature with a medial nuclear division phenotype. DNA replication is observed under these conditions, but most cells remain sensitive to hydroxyurea and do not complete the ongoing cell cycle if the drug is present during release from the temperature block. It is suggested that the cdc40 lesion affects an essential function in DNA synthesis. Normal meiosis is observed at the permissive temperature in cdc40 homozygotes. At the restrictive temperature, a full round of premeiotic DNA replication is observed, but neither commitment to recombination nor later meiotic events occur. Meiotic cells that are already committed to the recombination process at the permissive temperature do not complete it if transferred to the restrictive temperature before recombination is realized. These temperature shift-up experiments demonstrate that the CDC40 function is required for the completion of recom...
Journal of Cell Science, 1978
Yeast cells were cultivated at different growth rates in a chemostat by alterations in the flow of the limiting nutrient glucose and in batch cultures where variations in growth rate were achieved by alterations in the composition of nutrients. It was observed that the stage in the cycle at which 5-phase was completed varied with growth rate. The faster the growth rate, the earlier the stage in the cycle in which completion of S-phase occurred. When stage in the cycle is converted into time before division it was observed that the time from completion of S-phase to cell division varied only slightly with growth rate except at extremely slow growth rates. Expansion of cell cycle transit time as the growth rate was slowed was achieved primarily by an expansion in time of the period from division to the completion of .S-phase. In contrast, when cells were grown at different rates by alterations in the temperature of cultivation, completion of S-phase occurred at approximately the same stage in the cell cycle at all growth rates.
Transcriptional regulation of meiosis in budding yeast
International review of cytology, 2003
Initiation of meiosis in Saccharomyces cerevisiae is regulated by mating type and nutritional conditions that restrict meiosis to diploid cells grown under starvation conditions. Specifically, meiosis occurs in MATa/MATalpha cells shifted to nitrogen depletion media in the absence of glucose and the presence of a nonfermentable carbon source. These conditions lead to the expression and activation of Ime 1, the master regulator of meiosis. IME1 encodes a transcriptional activator recruited to promoters of early meiosis-specific genes by association with the DNA-binding protein, Ume6. Under vegetative growth conditions these genes are silent due to recruitment of the Sin3/Rpd3 histone deacetylase and Isw2 chromatin remodeling complexes by Ume6. Transcription of these meiotic genes occurs following histone acetylation by Gcn5. Expression of the early genes promote entry into the meiotic cycle, as they include genes required for premeiotic DNA synthesis, synapsis of homologous chromosom...
Regulation of mating and meiosis in yeast by the mating-type region
Genetics, 1976
A supposed sporulation-deficient mutation of Saccharomyces cerevisiae is found to affect mating in haploids and in diploids, and to be inseparable from the mating-type locus by recombination. The mutation is regarded as a defective a allele and is designated a*. This is confirmed by its dominance relations in diploids, triploids, and tetraploids. Tetrad analysis of tetraploids and of their sporulating diploid progeny suggests the existence of an additional locus, RME, which regulates sporulation in yeast strains that can mate. Thus the recessive homozygous constitution rme/rm- enables the diploids a*/alpha, a/a*, and alpha/alpha to go through meiosis. Haploids carrying rme show apparent premeiotic DNA replication in sporulation conditions. This new regulatory locus is linked to the centromere of the mating-type chromosome, and its two alleles, rme and RME, are found among standard laboratory strains.
Analysis of the kar3 Meiotic Arrest in Saccharomyces cerevisiae
Cell Cycle, 2004
The motor protein Kar3p and its associated protein Cik1p are essential for passage through meiosis I. In the absence of either protein, meiotic cells arrest in prophase I. Experiments were performed to determine whether the arrest was caused by a structural inability to proceed through meiosis, or by a regulatory mechanism. The data demonstrate that the meiotic arrest is not structural; kar3 and cik1 mutants are able to form normal looking bipolar spindles and divide their DNA into two masses in spo11 mutant backgrounds. To identify the regulatory system necessary for the kar3/cik1 meiotic arrest, we tested whether the arrest could be bypassed by eliminating the pachytene checkpoint or the spindle checkpoint. The arrest is not solely dependent upon the pachytene checkpoint that monitors recombination and aspects of chromosome synapsis. Elimination of the spindle checkpoint failed to allow kar3 mutants to undergo meiosis I nuclear division, but phenotypes of the kar3/spindle checkpoint double mutants suggest that the kar3 meiotic arrest may be mediated by the spindle checkpoint.
Synchronized meiosis and recombination in fission yeast: observations with pat1-114 diploid cells
Current Genetics, 1991
The mutation patl-II4 has been used to synchronize meiosis in the fission yeast Schizosaccharomyces pombe. We have investigated several aspects of such synchronized meiotic cultures. In both patl-ll4 and patl + diploids, meiotic landmark events are initiated at the same time after meiosis induction, but synchrony is much more pronounced in the patl-ll4-driven meiosis. Commitment to recombination and to meiosis have been timed at 2 h after meiotic induction. Due to a seven-fold reduction of intragenic recombination frequency in the ade6 region ofpatl-ll4 diploids, physical analysis of recombination has not been possible. We have distinguished three factors that inflhence intragenic recombination frequencies: temperature, azygotic versus zygotic meiosis, and the nature of the patl allele. Differences and similarities in the timing of meiotic landmarks in S. cerevisiae and S. pombe are discussed.
Effects of Age on Meiosis in Budding Yeast
Developmental Cell, 2009
In humans, the frequency with which meiotic chromosome mis-segregation occurs increases with age. Whether age-dependent meiotic defects occur in other organisms is unknown. Here, we examine the effects of replicative aging on meiosis in budding yeast. We find that aged mother cells show a decreased ability to initiate the meiotic program and fail to express the meiotic inducer IME1. The few aged mother cells that do enter meiosis complete this developmental program but exhibit defects in meiotic chromosome segregation and spore formation. Furthermore, we find that mutations that extend replicative life span also extend the sexual reproductive life span. Our results indicate that in budding yeast, the ability to initiate and complete the meiotic program as well as the fidelity of meiotic chromosome segregation decrease with cellular age and are controlled by the same pathways that govern aging of asexually reproducing yeast cells.