scholarly journals The relationship between the excess-delay phenomenon and temperature-sensitive periods in Tetrahymena thermophila

1980 ◽  
Vol 43 (1) ◽  
pp. 75-91
Author(s):  
J. Frankel ◽  
J. Mohler ◽  
A.K. Frankel
Keyword(s):  
Cell Division ◽  
Transition Point ◽  
Tetrahymena Thermophila ◽  
Characteristic Parameter ◽  
Sensitive Period ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Heat Shocks ◽  
Delay Phenomenon ◽  
The Relationship

Although temperatures of 37.5 and 39 degrees C allow continuous and rapid exponential growth of wild type Tetrahymena thermophila, sudden shifts up to these temperatures can bring about long excess-delays of cell division with accompanying resorption of developing oral primordia. A characteristic parameter of this delay-phenomenon is the physiological transition point, before which delays are maximal and after which they are negligible. When measured at a restrictive temperature that does not induce excess delays (36 degrees C), the end of the temperature-sensitive period of the cell division arrest of mutant cdaA1 precedes the physiological transition point, that of cdaH1 roughly coincides with it, while the entire temperature-sensitive period of cdaC2 comes after the physiological transition point. When cdaA1 cells are exposed to 37.5 degrees C or above, the manifestations of temperature sensitivity are drastically affected: the estimate of the end of the temperature-sensitive period (the execution point) becomes spuriously late, and the characteristic division arrest following heat shocks is not manifested. The differential effects of the higher restrictive temperatures on cdaH1 are most subtle, whereas those on cdaC2 are negligible. We conclude that the excess-delay phenomenon involves a set-back of genemediated processes occurring at specific stages of the cell cycle.

Temperature-sensitive periods of mutations affecting cell division in Tetrahymena thermophila

1980 ◽  
Vol 43 (1) ◽  
pp. 59-74 ◽  
Author(s):  
J. Frankel ◽  
J. Mohler ◽  
A.K. Frankel
Keyword(s):  
Cell Division ◽  
Tetrahymena Thermophila ◽  
Sensitive Period ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Physiological Effects ◽  
Sensitive Periods ◽  
Phenotypic Abnormality ◽  
Mutant Cells

Temperature-sensitive periods were determined by application of temperature shifts and shocks to 3 temperature-sensitive cell division arrest (cda) mutants of Tetrahymena thermophila. A restrictive temperature, 36 degrees C, was found at which all 3 mutants are fully penetrant, yet other physiological effects are minimal. At this temperature, the temperature-sensitive period of cdaC2 is a unique 5-min period in mid-division, that of cdaA1 is a similarly brief period situated about 0.5 h prior to cell division, while the temperature-sensitive period of cdaH1 is 20 to 30 min long and immediately precedes cell division. These periods either coincide with (cdaC2, cdaH1) or immediately precede (cdaA1) the onset of phenotypic abnormality at the restrictive temperature. Brief exposure to 36 degrees C during the temperature-sensitive period in any of these mutants brings about irreversible arrest of division furrows in progress or preparation. Mutant cells suffering such arrest can, however, divide again at a permissive temperature by forming new furrows at different sites.

scholarly journals THE SELECTION OF S. CEREVISIAE MUTANTS DEFECTIVE IN THE START EVENT OF CELL DIVISION

Genetics ◽  
1980 ◽  
Vol 95 (3) ◽  
pp. 561-577 ◽  
Author(s):  
Steven I Reed
Keyword(s):  
Cell Division ◽  
Genetic Analysis ◽  
Linkage Map ◽  
Nuclear Genes ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Mating Pheromone ◽  
Preliminary Characterization ◽  
Complementation Groups ◽  
Selection Of

ABSTRACT Thirty-three temperature-sensitive mutations defective in the start event of the cell division cycle of Saccharomyces cereuisiae were isolated and subjected to preliminary characterization. Complementation studies assigned these mutations to four complementation groups, one of which, cdc28, has been described previously. Genetic analysis revealed that these complementation groups define single nuclear genes, unlinked to one another. One of the three newly identified genes, cdc37, has been located in the yeast linkage map on chromosome IV, two meiotic map units distal to hom2.—Each mutation produces stage-specific arrest of cell division at start, the same point where mating pheromone interrupts division. After synchronization at start by incubation at the restrictive temperature, the mutants retain the capacity to enlarge and to conjugate.

Test for temporal or spatial restrictions in gene product function during the cell division cycle

1983 ◽  
Vol 3 (7) ◽  
pp. 1255-1265
Author(s):  
S K Dutcher ◽  
L H Hartwell
Keyword(s):  
Cell Division ◽  
Gene Product ◽  
Gene Mutations ◽  
Cell Division Cycle ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Product Function ◽  
Complete Cell ◽  
Relationship Of ◽  
Gene Product Function

The ability of a functional gene to complement a nonfunctional gene may depend upon the intracellular relationship of the two genes. If so, the function of the gene product in question must be limited in time or in space. CDC (cell division cycle) gene products of Saccharomyces cerevisiae control discrete steps in cell division; therefore, they constitute reasonable candidates for genes that function with temporal or spatial restrictions. In an attempt to reveal such restrictions, we compared the ability of a CDC gene to complement a temperature-sensitive cdc gene in diploids where the genes are located within the same nucleus to complementation in heterokaryons where the genes are located in different nuclei. In CDC X cdc matings, complementation was monitored in rare heterokaryons by assaying the production of cdc haploid progeny (cytoductants) at the restrictive temperature. The production of cdc cytoductants indicates that the cdc nucleus was able to complete cell division at the restrictive temperature and implies that the CDC gene product was provided by the other nucleus or by cytoplasm in the heterokaryon. Cytoductants from cdc28 or cdc37 crosses were not efficiently produced, suggesting that these two genes are restricted spatially or temporally in their function. We found that of the cdc mutants tested 33 were complemented; cdc cytoductants were recovered at least as frequently as CDC cytoductants. A particularly interesting example was provided by the CDC4 gene. Mutations in CDC4 were found previously to produce a defect in both cell division and karyogamy. Surprisingly, the cell division defect of cdc4 nuclei is complemented by CDC4 nuclei in a heterokaryon, whereas the karyogamy defect is not.

scholarly journals Cell cycle arrest of cdc mutants and specificity of the RAD9 checkpoint.

Genetics ◽  
1993 ◽  
Vol 134 (1) ◽  
pp. 63-80 ◽  
Author(s):  
T A Weinert ◽  
L H Hartwell
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Dna Replication ◽  
Cell Cycle Control ◽  
Dna Lesions ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
A Cell ◽  
G2 Phase ◽  
Rad Mutants

Abstract In eucaryotes a cell cycle control called a checkpoint ensures that mitosis occurs only after chromosomes are completely replicated and any damage is repaired. The function of this checkpoint in budding yeast requires the RAD9 gene. Here we examine the role of the RAD9 gene in the arrest of the 12 cell division cycle (cdc) mutants, temperature-sensitive lethal mutants that arrest in specific phases of the cell cycle at a restrictive temperature. We found that in four cdc mutants the cdc rad9 cells failed to arrest after a shift to the restrictive temperature, rather they continued cell division and died rapidly, whereas the cdc RAD cells arrested and remained viable. The cell cycle and genetic phenotypes of the 12 cdc RAD mutants indicate the function of the RAD9 checkpoint is phase-specific and signal-specific. First, the four cdc RAD mutants that required RAD9 each arrested in the late S/G2 phase after a shift to the restrictive temperature when DNA replication was complete or nearly complete, and second, each leaves DNA lesions when the CDC gene product is limiting for cell division. Three of the four CDC genes are known to encode DNA replication enzymes. We found that the RAD17 gene is also essential for the function of the RAD9 checkpoint because it is required for phase-specific arrest of the same four cdc mutants. We also show that both X- or UV-irradiated cells require the RAD9 and RAD17 genes for delay in the G2 phase. Together, these results indicate that the RAD9 checkpoint is apparently activated only by DNA lesions and arrests cell division only in the late S/G2 phase.

scholarly journals RPC53 encodes a subunit of Saccharomyces cerevisiae RNA polymerase C (III) whose inactivation leads to a predominantly G1 arrest.

1992 ◽  
Vol 12 (10) ◽  
pp. 4314-4326 ◽  
Author(s):  
C Mann ◽  
J Y Micouin ◽  
N Chiannilkulchai ◽  
I Treich ◽  
J M Buhler ◽  
...  
Keyword(s):  
Cell Division ◽  
Amino Acid ◽  
Rna Polymerase ◽  
Essential Gene ◽  
Temperature Sensitive ◽  
G1 Arrest ◽  
Restrictive Temperature ◽  
Amino Acid Residues ◽  
Gene Encoding ◽  
Carboxy Terminal

RPC53 is shown to be an essential gene encoding the C53 subunit specifically associated with yeast RNA polymerase C (III). Temperature-sensitive rpc53 mutants were generated and showed a rapid inhibition of tRNA synthesis after transfer to the restrictive temperature. Unexpectedly, the rpc53 mutants preferentially arrested their cell division in the G1 phase as large, round, unbudded cells. The RPC53 DNA sequence is predicted to code for a hydrophilic M(r)-46,916 protein enriched in charged amino acid residues. The carboxy-terminal 136 amino acids of C53 are significantly similar (25% identical amino acid residues) to the same region of the human BN51 protein. The BN51 cDNA was originally isolated by its ability to complement a temperature-sensitive hamster cell mutant that undergoes a G1 cell division arrest, as is true for the rpc53 mutants.

DIPLOID SPORE FORMATION AND OTHER MEIOTIC EFFECTS OF TWO CELL-DIVISION-CYCLE MUTATIONS OF SACCHAROMYCES CEREVISIAE

Genetics ◽  
1980 ◽  
Vol 96 (4) ◽  
pp. 859-876 ◽  
Author(s):  
David Schild ◽  
Breck Byers
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Spindle Pole Body ◽  
Spindle Pole ◽  
Cell Division Cycle ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Single Spore ◽  
Diploid Cells ◽  
Meiosis I

ABSTRACT The meiotic effects of two cell-division-cycle mutations of Saccharomyces cerevisiae (cdc5 and cdc14) have been examined. These mutations were isolated by L. H. Hartwell and his colleagues and characterized as defective in mitosis, causing a temperature-sensitive arrest in late nuclear division. When subjected to the restrictive temperature in meiosis, diploid cells homozygous for either of these mutations generally proceeded through premeiotic DNA synthesis and commitment to meiotic levels of recombination, but then arrested at a stage following spindle pole body (SPB) duplication and separation. The two SPBs lacked the interconnection by spindle microtubules typical of the complete meiosis I spindle. Challenge of these homozygotes by a semi-restrictive temperature often caused the production of asci containing two diploid spores. Genetic analysis of the viable pairs of spores revealed that each spore had become homozygous for centromere-linked markers significantly more frequently than for distal markers, indicating that the two spores each contained pairs of sister centromeres that had co-segregated in the reductional division of meiosis I. Ultrastructural analysis of the cdc5 homozygote demonstrated that these cells had completed meiosis I and formed two meiosis II spindles, but that the latter remained unusually short. This resulted in the encapsulation of both poles of each spindle within a single spore wall. These mutations therefore are defective in both meiotic divisions, as well as in the mitotic division described originally.

scholarly journals THE RELATIONSHIP BETWEEN DEOXYRIBONUCLEIC ACID REPLICATION AND CELL DIVISION IN HEAT-SYNCHRONIZED TETRAHYMENA

1970 ◽  
Vol 46 (3) ◽  
pp. 533-543 ◽  
Author(s):  
William R. Jeffery ◽  
Kenneth D. Stuart ◽  
Joseph Frankel
Keyword(s):  
Cell Division ◽  
Heat Shock ◽  
Dna Synthesis ◽  
Deoxyribonucleic Acid ◽  
Heat Shock Treatment ◽  
Heat Shocks ◽  
Prolonged Heat ◽  
S Period ◽  
C 50 ◽  
The Relationship

The effect of supraoptimal temperature on macronuclear DNA synthesis in Tetrahymena was studied by radioautography during prolonged heat and heat-shock synchronization treatments. Prolonged heat treatments (34°C) delayed the initiation of S, but did not appreciably delay DNA synthesis in progress. Return to optimal temperature (28°C) 50 or 100 min later resulted in initiation of S, in delayed cells, at a rate greater than in controls. During the synchronization treatment, most cells were unable to enter S during a heat shock, but initiated S with a slight delay during the following intershock period. These cells were not appreciably delayed in completion of S by subsequent heat shocks. Supraoptimal temperature appears to affect the DNA synthetic cycle near the G1 to S transition. Cells subjected to the heat-shock treatment in early G1 all participated in one S period, and many underwent a succession of two S periods. DNA synthesis occurred in about 50% of the cells between EST and the first synchronous division, with the likelihood of DNA synthesis becoming greater the longer the interval between these two events. In some cells no detectable DNA synthesis occurred between EST and the second synchronous division. It was concluded that a precise temporal alternation of DNA replication and cell division is not obligatory in Tetrahymena.

scholarly journals Interaction between the plasmid R6K andEscherichia coliwith defective DNA polymerase I

1978 ◽  
Vol 32 (1) ◽  
pp. 25-35 ◽  
Author(s):  
D. J. Tweats ◽  
J. T. Smith
Keyword(s):  
Cell Division ◽  
Dna Polymerase ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Dna Polymerase I ◽  
E Coli ◽  
R Factor ◽  
Polymerase I

SUMMARYInitial experiments demonstrated that the plasmid R6K cannot be transferred to or maintained readily in theE. coliDNA polymerase I deficient strain JG138polA1. Results withE. coliMM386polA12(R6K), which has a temperature sensitive polymerase I enzyme, showed cell division becomes abnormal when the polymerase I enzyme of the host bacteria is inactivated at the restrictive temperature. Under conditions of polymerase I deficiency, R6K replication, as measured by monitoring R-factor-mediated β-lactamase activity, also becomes abnormal with the loss of multiple R6K copies per cell and the apparent maintenance of a single R-factor copy per cell.

RPC53 encodes a subunit of Saccharomyces cerevisiae RNA polymerase C (III) whose inactivation leads to a predominantly G1 arrest

1992 ◽  
Vol 12 (10) ◽  
pp. 4314-4326
Author(s):  
C Mann ◽  
J Y Micouin ◽  
N Chiannilkulchai ◽  
I Treich ◽  
J M Buhler ◽  
...  
Keyword(s):  
Cell Division ◽  
Amino Acid ◽  
Rna Polymerase ◽  
Essential Gene ◽  
Temperature Sensitive ◽  
G1 Arrest ◽  
Restrictive Temperature ◽  
Amino Acid Residues ◽  
Gene Encoding ◽  
Carboxy Terminal

RPC53 is shown to be an essential gene encoding the C53 subunit specifically associated with yeast RNA polymerase C (III). Temperature-sensitive rpc53 mutants were generated and showed a rapid inhibition of tRNA synthesis after transfer to the restrictive temperature. Unexpectedly, the rpc53 mutants preferentially arrested their cell division in the G1 phase as large, round, unbudded cells. The RPC53 DNA sequence is predicted to code for a hydrophilic M(r)-46,916 protein enriched in charged amino acid residues. The carboxy-terminal 136 amino acids of C53 are significantly similar (25% identical amino acid residues) to the same region of the human BN51 protein. The BN51 cDNA was originally isolated by its ability to complement a temperature-sensitive hamster cell mutant that undergoes a G1 cell division arrest, as is true for the rpc53 mutants.

scholarly journals GENETIC CONTROL OF THE CELL DIVISION CYCLE IN YEAST: V. GENETIC ANALYSIS OF cdc MUTANTS

Genetics ◽  
1973 ◽  
Vol 74 (2) ◽  
pp. 267-286
Author(s):  
Leland H Hartwell ◽  
Robert K Mortimer ◽  
Joseph Culotti ◽  
Marilyn Culotti
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Nuclear Gene ◽  
Temperature Shift ◽  
Time Lapse ◽  
Cell Division Cycle ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Gene Products ◽  
Diploid Cells

ABSTRACT One hundred and forty-eight temperature-sensitive cell division cycle (cdc) mutants of Saccharomyces cerevisiae have been isolated and characterized. Complementation studies ordered these recessive mutations into 32 groups and tetrad analysis revealed that each of these groups defines a single nuclear gene. Fourteen of these genes have been located on the yeast genetic map. Functionally related cistrons are not tightly clustered. Mutations in different cistrons frequently produce different cellular and nuclear morphologies in the mutant cells following incubation at the restrictive temperature, but all the mutations in the same cistron produce essentially the same morphology. The products of these genes appear, therefore, each to function individually in a discrete step of the cell cycle and they define collectively a large number of different steps. The mutants were examined by time-lapse photomicroscopy to determine the number of cell cycles completed at the restrictive temperature before arrest. For most mutants, cells early in the cell cycle at the time of the temperature shift (before the execution point) arrest in the first cell cycle while those later in the cycle (after the execution point) arrest in the second cell cycle. Execution points for allelic mutations that exhibit first or second cycle arrest are rather similar and appear to be cistron-specific. Other mutants traverse several cycles before arrest, and its suggested that the latter type of response may reveal gene products that are temperature-sensitive for synthesis, whereas the former may be temperature-sensitive for function. The gene products that are defined by the cdc cistrons are essential for the completion of the cell cycle in haploids of a and α mating type and in a/α diploid cells. The same genes, therefore, control the cell cycle in each of these stages of the life cycle.

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