scholarly journals Regulation of mating in the cell cycle of Saccharomyces cerevisiae.

1977 ◽  
Vol 75 (2) ◽  
pp. 355-365 ◽  
Author(s):  
B J Reid ◽  
L H Hartwell
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
High Frequency ◽  
Nuclear Division ◽  
Diploid Cell ◽  
Yeast Cells ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Haploid Strain ◽  
Cdc 2

The capacity of haploid a yeast cells to mate (fuse with a haploid strain of alpha mating type followed by nuclear fusion to produce a diploid cell) was assessed for a variety of temperature-sensitive cell division cycle (cdc) mutants at the permissive and restrictive temperatures. Asynchronous populations of some mutants do not mate at the restrictive temperature, and these mutants define genes (cdc 1, 4, 24, and 33) that are essential both for the cell cycle and for mating. For most cdc mutants, asynchronous populations mate well at the restrictive temperature while populations synchronized at the cdc block do not. Populations of a mutant carrying the cdc 28 mutation mate well at the restrictive temperature after synchronization at the cdc 28 step. These results suggest that mating can occur from the cdc 28 step, the same step at which mating factors arrest cell cycle progress. The cell cycle interval in which mating can occur may or may not extend to the immediately succeeding and diverging steps (cdc 4 and cdc 24). High frequency mating does not occur in the interval of the cell cycle extending from the step before the initiation of DNA synthesis (cdc 7) through DNA synthesis (cdc 2, 8, and 21), medial nuclear division (cdc 13), and late nuclear division (cdc 14 and 15).

scholarly journals MEIOTIC RECOMBINATION AND DNA SYNTHESIS IN A NEW CELL CYCLE MUTANT OF SACCHAROMYCES CEREVISIAE

Genetics ◽  
1978 ◽  
Vol 90 (1) ◽  
pp. 49-68
Author(s):  
Yona Kassir ◽  
Giora Simchen
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Nuclear Division ◽  
Temperature Shift ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Essential Function ◽  
Normal Meiosis

ABSTRACT 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 recombination events, as well as for the earlier stage of recombination commitment. Temperature shift-down experiments with cdc40 homozygotes suggest that meiotic segregation depends on the final events of recombination rather than on commitment to recombination.

scholarly journals Role of Bud3p in producing the axial budding pattern of yeast.

1995 ◽  
Vol 129 (3) ◽  
pp. 767-778 ◽  
Author(s):  
J Chant ◽  
M Mischke ◽  
E Mitchell ◽  
I Herskowitz ◽  
J R Pringle
Keyword(s):  
Cell Cycle ◽  
Yeast Cells ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Alpha Cells ◽  
Double Ring ◽  
Division Site ◽  
Bud Emergence ◽  
Mother And Daughter ◽  
Associated Proteins

Yeast cells can select bud sites in either of two distinct spatial patterns. a cells and alpha cells typically bud in an axial pattern, in which both mother and daughter cells form new buds adjacent to the preceding division site. In contrast, a/alpha cells typically bud in a bipolar pattern, in which new buds can form at either pole of the cell. The BUD3 gene is specifically required for the axial pattern of budding: mutations of BUD3 (including a deletion) affect the axial pattern but not the bipolar pattern. The sequence of BUD3 predicts a product (Bud3p) of 1635 amino acids with no strong or instructive similarities to previously known proteins. However, immunofluorescence localization of Bud3p has revealed that it assembles in an apparent double ring encircling the mother-bud neck shortly after the mitotic spindle forms. The Bud3p structure at the neck persists until cytokinesis, when it splits to yield a single ring of Bud3p marking the division site on each of the two progeny cells. These single rings remain for much of the ensuing unbudded phase and then disassemble. The Bud3p rings are indistinguishable from those of the neck filament-associated proteins (Cdc3p, Cdc10p, Cdc11p, and Cdc12p), except that the latter proteins assemble before bud emergence and remain in place for the duration of the cell cycle. Upon shift of a temperature-sensitive cdc12 mutant to restrictive temperature, localization of both Bud3p and the neck filament-associated proteins is rapidly lost. In addition, a haploid cdc11 mutant loses its axial-budding pattern upon shift to restrictive temperature. Taken together, the data suggest that Bud3p and the neck filaments are linked in a cycle in which each controls the position of the other's assembly: Bud3p assembles onto the neck filaments in one cell cycle to mark the site for axial budding (including assembly of the new ring of neck filaments) in the next cell cycle. As the expression and localization of Bud3p are similar in a, alpha, and a/alpha cells, additional regulation must exist such that Bud3p restricts the position of bud formation in a and alpha cells but not in a/alpha cells.

The product of the Saccharomyces cerevisiae cell cycle gene DBF2 has homology with protein kinases and is periodically expressed in the cell cycle

1990 ◽  
Vol 10 (4) ◽  
pp. 1358-1366
Author(s):  
L H Johnston ◽  
S L Eberly ◽  
J W Chapman ◽  
H Araki ◽  
A Sugino
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Dna Synthesis ◽  
Protein Kinases ◽  
Nuclear Division ◽  
Cell Cycle Gene ◽  
Restrictive Temperature ◽  
Histone H2a ◽  
Reading Frame ◽  
Polymerase I

Several Saccharomyces cerevisiae dbf mutants defective in DNA synthesis have been described previously. In this paper, one of them, dbf2, is characterized in detail. The DBF2 gene has been cloned and mapped, and its nucleotide sequence has been determined. This process has identified an open reading frame capable of encoding a protein of molecular weight 64,883 (561 amino acids). The deduced amino acid sequence contains all 11 conserved domains found in various protein kinases. DBF2 was periodically expressed in the cell cycle at a time that clearly differed from the time of expression of either the histone H2A or DNA polymerase I gene. Its first function was completed very near to initiation of DNA synthesis. However, DNA synthesis in the mutant was only delayed at 37 degrees C, and the cells blocked in nuclear division. Consistent with this finding, the execution point occurred about 1 h after DNA synthesis, and the nuclear morphology of the mutant at the restrictive temperature was that of cells blocked in late nuclear division. DBF2 is therefore likely to encode a protein kinase that may function in initiation of DNA synthesis and also in late nuclear division.

scholarly journals The product of the Saccharomyces cerevisiae cell cycle gene DBF2 has homology with protein kinases and is periodically expressed in the cell cycle.

1990 ◽  
Vol 10 (4) ◽  
pp. 1358-1366 ◽  
Author(s):  
L H Johnston ◽  
S L Eberly ◽  
J W Chapman ◽  
H Araki ◽  
A Sugino
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Dna Synthesis ◽  
Protein Kinases ◽  
Nuclear Division ◽  
Cell Cycle Gene ◽  
Restrictive Temperature ◽  
Histone H2a ◽  
Reading Frame ◽  
Polymerase I

Several Saccharomyces cerevisiae dbf mutants defective in DNA synthesis have been described previously. In this paper, one of them, dbf2, is characterized in detail. The DBF2 gene has been cloned and mapped, and its nucleotide sequence has been determined. This process has identified an open reading frame capable of encoding a protein of molecular weight 64,883 (561 amino acids). The deduced amino acid sequence contains all 11 conserved domains found in various protein kinases. DBF2 was periodically expressed in the cell cycle at a time that clearly differed from the time of expression of either the histone H2A or DNA polymerase I gene. Its first function was completed very near to initiation of DNA synthesis. However, DNA synthesis in the mutant was only delayed at 37 degrees C, and the cells blocked in nuclear division. Consistent with this finding, the execution point occurred about 1 h after DNA synthesis, and the nuclear morphology of the mutant at the restrictive temperature was that of cells blocked in late nuclear division. DBF2 is therefore likely to encode a protein kinase that may function in initiation of DNA synthesis and also in late nuclear division.

The PHOA and PHOB Cyclin-Dependent Kinases Perform an Essential Function in Aspergillus nidulans

Genetics ◽  
2003 ◽  
Vol 165 (3) ◽  
pp. 1105-1115
Author(s):  
Xiaowei Dou ◽  
Dongliang Wu ◽  
Weiling An ◽  
Jonathan Davies ◽  
Shahr B Hashmi ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Aspergillus Nidulans ◽  
Nuclear Division ◽  
Cell Cycle Control ◽  
Dominant Negative ◽  
Null Alleles ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Cyclin Dependent Kinase ◽  
Essential Function

Abstract Unlike Pho85 of Saccharomyces cerevisiae, the highly related PHOA cyclin-dependent kinase (CDK) of Aspergillus nidulans plays no role in regulation of enzymes involved in phosphorous acquisition but instead modulates differentiation in response to environmental conditions, including limited phosphorous. Like PHO85, Aspergillus phoA is a nonessential gene. However, we find that expression of dominant-negative PHOA inhibits growth, suggesting it may have an essential but redundant function. Supporting this we have identified another cyclin-dependent kinase, PHOB, which is 77% identical to PHOA. Deletion of phoB causes no phenotype, even under phosphorous-limited growth conditions. To investigate the function of phoA/phoB, double mutants were selected from a cross of strains containing null alleles and by generating a temperature-sensitive allele of phoA in a ΔphoB background. Double-deleted ascospores were able to germinate but had a limited capacity for nuclear division, suggesting a cell cycle defect. Longer germination revealed morphological defects. The temperature-sensitive phoA allele caused both nuclear division and polarity defects at restrictive temperature, which could be complemented by expression of mammalian CDK5. Therefore, an essential function exists in A. nidulans for the Pho85-like kinase pair PHOA and PHOB, which may involve cell cycle control and morphogenesis.

scholarly journals Causal relations among cell cycle processes in Tetrahymena pyriformis. An analysis employing temperature-sensitive mutants.

1976 ◽  
Vol 71 (1) ◽  
pp. 242-260 ◽  
Author(s):  
J Frankel ◽  
L M Jenkins ◽  
L E DeBault
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Synthesis ◽  
Tetrahymena Pyriformis ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Developmental Pathway ◽  
Temperature Sensitive Mutants ◽  
Oral Development ◽  
Macronuclear Division

Utilization of temperature-sensitive mutants of Tetrahymena pyriformis affected in cell division or developmental pathway selection has permitted elucidation of causal dependencies interrelating micronuclear and macronuclear replication and division, oral development, and cytokinesis. In those mutants in which cell division is specifically blocked at restrictive temperatures, micronuclear division proceeds with somewhat accelerated periodicity but maintains normal coupling to predivision oral development. Macronuclear division is almost totally suppressed in an early acting mutant (mola) that prevents formation of the fission zone, and is variably affected in other mutants (such as mo3) that allow the fission zone to form but arrest constriction. However, macronuclear DNA synthesis can proceed for about four cycles in the nondividing mutant cells. A second class of mutants (psm) undergoes a switch of developmental pathway such that cells fail to enter division but instead repeatedly carry out an unusual type of oral replacement while growing in nutrient medium at the restrictive temperature. Under these circumstances no nuclei divide, yet macronuclear DNA accumulation continues. These results suggest that (a) macronuclear division is stringently affected by restriction of cell division, (b) micronuclear division and replication can continue in cells that are undergoing the type of oral development that is characteristic of division cycles, and (c) macronuclear DNA synthesis can continue in growing cells regardless of their developmental status. The observed relationships among events are consistent with the further suggestion that the cell cycle in this organism may consist of separate clusters of events. with a varying degree of coupling among clusters. A minimal model of the Tetrahymena cell cycle that takes these phenomena into account is suggested.

scholarly journals A search for temperature-sensitive mutants ofUstilago maydisblocked in DNA synthesis

1970 ◽  
Vol 15 (2) ◽  
pp. 157-169 ◽  
Author(s):  
P. Unrau ◽  
R. Holliday
Keyword(s):  
Dna Synthesis ◽  
Nuclear Division ◽  
Ustilago Maydis ◽  
Temperature Treatment ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Temperature Sensitive Mutants ◽  
Dna And Rna

SUMMARYOver 400 temperature-sensitive mutants ofUstilago maydishave been tested for DNA synthesis at the restrictive temperature of 32°C by measuring14C adenine incorporation into DNA and RNA. Five mutants were defective in DNA synthesis but none was completely blocked. One mutant,tsd-1, which is unlinked to the others, forms long uninucleate filaments at 32°C which die exponentially after 4h temperature treatment. The phenotype is comparable to that of thymine-starved bacteria, but it is possible that rather than being specifically defective in DNA synthesis the mutant is blocked in nuclear division.

Identification of temperature-sensitive DNA- mutants of Chinese hamster cells affected in cellular and viral DNA synthesis

1986 ◽  
Vol 6 (12) ◽  
pp. 4594-4601
Author(s):  
J J Dermody ◽  
B E Wojcik ◽  
H Du ◽  
H L Ozer
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Chinese Hamster ◽  
Human Adenovirus ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Dependent Manner ◽  
Viral Dna ◽  
Cell Functions

We described a strategy which facilitates the identification of cell mutants which are restricted in DNA synthesis in a temperature-dependent manner. A collection of over 200 cell mutants temperature-sensitive for growth was isolated in established Chinese hamster cell lines (CHO and V79) by a variety of selective and nonselective techniques. Approximately 10% of these mutants were identified as ts DNA- based on differential inhibition of macromolecular synthesis at the restrictive temperature (39 degrees C) as assessed by incorporation of [3H]thymidine and [35S]methionine. Nine such mutants, selected for further study, demonstrated rapid shutoff of DNA replication at 39 degrees C. Infections with two classes of DNA viruses extensively dependent on host-cell functions for their replication were used to distinguish defects in DNA synthesis itself from those predominantly affecting other aspects of DNA replication. All cell mutants supported human adenovirus type 2 (Ad2) and mouse polyomavirus DNA synthesis at the permissive temperature. Five of the nine mutants (JB3-B, JB3-O, JB7-K, JB8-D, and JB11-J) restricted polyomavirus DNA replication upon transfection with viral sequences at 33 degrees C and subsequent shift to 39 degrees C either before or after the onset of viral DNA synthesis. Only one of these mutants (JB3-B) also restricted Ad2 DNA synthesis after virion infection under comparable conditions. No mutant was both restrictive for Ad2 and permissive for polyomavirus DNA synthesis at 39 degrees C. The differential effect of these cell mutants on viral DNA synthesis is expected to assist subsequent definition of the biochemical defect responsible.

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