Temperature regulation of nuclear division in apomictic yeast

1984 ◽  
Vol 30 (6) ◽  
pp. 793-797 ◽  
Author(s):  
Carl A. Bilinski ◽  
John J. Miller

The effect of temperature on nuclear division and spore formation in an apomictic, two-spored strain of Saccharomyces cerevisiae (19e1) was investigated. Presporulation culture at 36 °C increased markedly the frequency of asci containing three or four spores that developed in sporulation medium, indicating a morphogenic role for temperature in control of meiosis in apomictic yeast. Mild temperature shock treatments administered to cells shortly after transfer from presporulation to sporulation medium also promoted nuclear division and three classes of asci developed: binucleate, trinucleate, and tetranucleate. Nuclear divisions were not always completed before the onset of spore formation in trinucleate asci.

1983 ◽  
Vol 3 (3) ◽  
pp. 457-465
Author(s):  
C H Kim ◽  
J R Warner

In Saccharomyces cerevisiae the synthesis of ribosomal proteins declines temporarily after a culture has been subjected to a mild temperature shock, i.e., a shift from 23 to 36 degrees C, each of which support growth. Using cloned genes for several S. cerevisiae ribosomal proteins, we found that the changes in the synthesis of ribosomal proteins parallel the changes in the concentration of mRNA of each. The disappearance and reappearance of the mRNA is due to a brief but severe inhibition of the transcription of each of the ribosomal protein genes, although the total transcription of mRNA in the cells is relatively unaffected by the temperature shock. The precisely coordinated response of these genes, which are scattered throughout the genome, suggests that either they or the enzyme which transcribes them has unique properties. In certain S. cerevisiae mutants, the synthesis of ribosomal proteins never recovers from a temperature shift. Yet both the decline and the resumption of transcription of these genes during the 30 min after the temperature shift are indistinguishable from those in wild-type cells. The failure of the mutant cells to grow at the restrictive temperature appears to be due to their inability to process the RNA transcribed from genes which have introns (Rosbash et al., Cell 24:679-686, 1981), a large proportion of which appear to be ribosomal protein genes.


1986 ◽  
Vol 6 (6) ◽  
pp. 2185-2197 ◽  
Author(s):  
E Gottlin-Ninfa ◽  
D B Kaback

Strains of the yeast Saccharomyces cerevisiae that are heterozygous for the mating-type locus (MATa/MAT alpha) undergo meiosis and spore formation when they are starved for nitrogen and are provided with a nonfermentable carbon source such as potassium acetate. Haploids and diploids homozygous for the mating-type locus (MAT alpha/MAT alpha or MATa/MATa) are asporogenous and undergo neither meiosis nor spore formation when incubated under the same conditions. A small number of genes produce transcripts that appear to be induced specifically in sporulating cells. These transcripts either are not found or are present at much lower levels both in vegetatively growing cells and in cells from asporogenous strains that have been incubated in sporulation medium. Several genes complementary to these MATa/MAT alpha-dependent sporulation-induced transcripts were isolated from a gene-size insert yeast-lambda recombinant DNA library, by differential-plaque filter hybridization. An attempt was made to determine the function of three of these genes by mutating them in the yeast genome with in vitro mutagenesis and one-step gene replacement techniques. One gene was extensively disrupted by both a 0.3-kilobase deletion and the insertion of two large DNA sequences at different sites within the gene. Surprisingly, this compound mutation did not appear to affect meiosis or the production of viable ascospores, indicating that this gene was dispensable for differentiation. The other two genes were disrupted by simple insertion mutations at a site where it was possible that they might still possess some gene activity. These mutations also did not appear to affect sporulation. These results suggest that not all sporulation-induced genes are essential for meiosis and the production of viable ascospores under the conditions examined.


1997 ◽  
Vol 17 (12) ◽  
pp. 7029-7039 ◽  
Author(s):  
D K Nag ◽  
M P Koonce ◽  
J Axelrod

During meiosis, a diploid cell undergoes two rounds of nuclear division following one round of DNA replication to produce four haploid gametes. In yeast, haploid meiotic products are packaged into spores. To gain new insights into meiotic development and spore formation, we followed differential expression of genes in meiotic versus vegetatively growing cells in the yeast Saccharomyces cerevisiae. Our results indicate that there are at least five different classes of transcripts representing genes expressed at different stages of the sporulation program. Here we describe one of these differentially expressed genes, SSP1, which plays an essential role in meiosis and spore formation. SSP1 is expressed midway through meiosis, and homozygous ssp1 diploid cells fail to sporulate. In the ssp1 mutant, meiotic recombination is normal but viability declines rapidly. Both meiotic divisions occur at the normal time; however, the fraction of cells completing meiosis is significantly reduced, and nuclei become fragmented soon after meiosis II. The ssp1 defect does not appear to be related to a microtubule-cytoskeletal-dependent event and is independent of two rounds of chromosome segregation. The data suggest that Ssp1 is likely to function in a pathway that controls meiotic nuclear divisions and coordinates meiosis and spore formation.


1962 ◽  
Vol 8 (4) ◽  
pp. 573-584 ◽  
Author(s):  
R. D. Pontefract ◽  
J. J. Miller

Parallel observations were made of respiratory activity, content of glycogen and fat, and appearance of the nucleus, during transition of cells of Saccharomyces cerevisiae from the vegetative to the sporulated state. With acetate as the carbon source in sporulation medium, the endogenous respiratory ability of the cells first increased (after about 10 hours) and finally declined. Ability to respire glucose remained high during sporogenesis but diminished somewhat by 42–43 hours, at which time most of the cells contained spores. Glycogen and fat increased in amount during the early stages of sporogenesis but appeared to diminish during formation of spore walls. In vegetative and reductional nuclear division the nuclear material appeared organized into rod-like structures, some regions of which stained more densely. Classical cytological configurations were not observed. With dihydroxyacetone as the carbon source in sporulation medium the sequence of events was similar, but required about twice as much time, possibly owing to the slower respiration of this substance.


1983 ◽  
Vol 3 (3) ◽  
pp. 457-465 ◽  
Author(s):  
C H Kim ◽  
J R Warner

In Saccharomyces cerevisiae the synthesis of ribosomal proteins declines temporarily after a culture has been subjected to a mild temperature shock, i.e., a shift from 23 to 36 degrees C, each of which support growth. Using cloned genes for several S. cerevisiae ribosomal proteins, we found that the changes in the synthesis of ribosomal proteins parallel the changes in the concentration of mRNA of each. The disappearance and reappearance of the mRNA is due to a brief but severe inhibition of the transcription of each of the ribosomal protein genes, although the total transcription of mRNA in the cells is relatively unaffected by the temperature shock. The precisely coordinated response of these genes, which are scattered throughout the genome, suggests that either they or the enzyme which transcribes them has unique properties. In certain S. cerevisiae mutants, the synthesis of ribosomal proteins never recovers from a temperature shift. Yet both the decline and the resumption of transcription of these genes during the 30 min after the temperature shift are indistinguishable from those in wild-type cells. The failure of the mutant cells to grow at the restrictive temperature appears to be due to their inability to process the RNA transcribed from genes which have introns (Rosbash et al., Cell 24:679-686, 1981), a large proportion of which appear to be ribosomal protein genes.


1986 ◽  
Vol 6 (6) ◽  
pp. 2185-2197
Author(s):  
E Gottlin-Ninfa ◽  
D B Kaback

Strains of the yeast Saccharomyces cerevisiae that are heterozygous for the mating-type locus (MATa/MAT alpha) undergo meiosis and spore formation when they are starved for nitrogen and are provided with a nonfermentable carbon source such as potassium acetate. Haploids and diploids homozygous for the mating-type locus (MAT alpha/MAT alpha or MATa/MATa) are asporogenous and undergo neither meiosis nor spore formation when incubated under the same conditions. A small number of genes produce transcripts that appear to be induced specifically in sporulating cells. These transcripts either are not found or are present at much lower levels both in vegetatively growing cells and in cells from asporogenous strains that have been incubated in sporulation medium. Several genes complementary to these MATa/MAT alpha-dependent sporulation-induced transcripts were isolated from a gene-size insert yeast-lambda recombinant DNA library, by differential-plaque filter hybridization. An attempt was made to determine the function of three of these genes by mutating them in the yeast genome with in vitro mutagenesis and one-step gene replacement techniques. One gene was extensively disrupted by both a 0.3-kilobase deletion and the insertion of two large DNA sequences at different sites within the gene. Surprisingly, this compound mutation did not appear to affect meiosis or the production of viable ascospores, indicating that this gene was dispensable for differentiation. The other two genes were disrupted by simple insertion mutations at a site where it was possible that they might still possess some gene activity. These mutations also did not appear to affect sporulation. These results suggest that not all sporulation-induced genes are essential for meiosis and the production of viable ascospores under the conditions examined.


2005 ◽  
Vol 4 (4) ◽  
pp. 832-835 ◽  
Author(s):  
Terri S. Rice ◽  
Min Ding ◽  
David S. Pederson ◽  
Nicholas H. Heintz

ABSTRACT Here we show that the Saccharomyces cerevisiae tRNAHis guanylyltransferase Thg1p interacts with the origin recognition complex in vivo and in vitro and that overexpression of hemagglutinin-Thg1p selectively impedes growth of orc2-1(Ts) cells at the permissive temperature. Studies with conditional mutants indicate that Thg1p couples nuclear division and migration to cell budding and cytokinesis in yeast.


1990 ◽  
Vol 10 (5) ◽  
pp. 2104-2110
Author(s):  
A P Mitchell ◽  
S E Driscoll ◽  
H E Smith

In the yeast Saccharomyces cerevisiae, meiosis and spore formation require the induction of sporulation-specific genes. Two genes are thought to activate the sporulation program: IME1 and IME2 (inducer of meiosis). Both genes are induced upon entry into meiosis, and IME1 is required for IME2 expression. We report here that IME1 is essential for expression of four sporulation-specific genes. In contrast, IME2 is not absolutely essential for expression of the sporulation-specific genes, but contributes to their rapid induction. Expression of IME2 from a heterologous promoter permits the expression of these sporulation-specific genes, meiotic recombination, and spore formation in the absence of IME1. We propose that the IME1 and IME2 products can each activate sporulation-specific genes independently. In addition, the IME1 product stimulates sporulation-specific gene expression indirectly through activation of IME2 expression.


1989 ◽  
Vol 9 (9) ◽  
pp. 3992-3998
Author(s):  
A M Dranginis

STA1 encodes a secreted glucoamylase of the yeast Saccharomyces cerevisiae var. diastaticus. Glucoamylase secretion is controlled by the mating type locus MAT; a and alpha haploid yeast cells secrete high levels of the enzyme, but a/alpha diploid cells produce undetectable amounts. It has been suggested that STA1 is regulated by MATa2 (I. Yamashita, Y. Takano, and S. Fukui, J. Bacteriol. 164:769-773, 1985), which is a MAT transcript of previously unknown function. In contrast, this work shows that deletion of the entire MATa2 gene had no effect on STA1 regulation but that deletion of MATa1 sequences completely abolished mating-type control. In all cases, glucoamylase activity levels reflected STA1 mRNA levels. It appears that STA1 is a haploid-specific gene that is regulated by MATa1 and a product of the MAT alpha locus and that this regulation occurs at the level of RNA accumulation. STA1 expression was also shown to be glucose repressible. STA1 mRNA was induced in diploids during sporulation along with SGA, a closely linked gene that encodes an intracellular sporulation-specific glucoamylase of S. cerevisiae. A diploid strain with a MATa1 deletion showed normal induction of STA1 in sporulation medium, but SGA expression was abolished. Therefore, these two homologous and closely linked glucoamylase genes are induced by different mechanisms during sporulation. STA1 induction may be a response to the starvation conditions necessary for sporulation, while SGA induction is governed by the pathway by which MAT regulates sporulation. The strain containing a complete deletion of MATa2 grew, mated, and sporulated normally.


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