scholarly journals Developmental regulation of SPO13, a gene required for separation of homologous chromosomes at meiosis I.

1987 ◽  
Vol 7 (4) ◽  
pp. 1425-1435 ◽  
Author(s):  
H T Wang ◽  
S Frackman ◽  
J Kowalisyn ◽  
R E Esposito ◽  
R Elder
Keyword(s):  
Genetic Recombination ◽  
Developmental Regulation ◽  
Maximum Level ◽  
Mitotic Cell ◽  
Sporulation Medium ◽  
Developmentally Regulated ◽  
Type Locus ◽  
Homologous Chromosomes ◽  
Diploid Cells ◽  
Meiosis I

Previous studies have demonstrated that the SPO13 gene is required for chromosome separation during meiosis I in Saccharomyces cerevisiae. In the presence of the spo13-1 nonsense mutation, MATa/MAT alpha diploid cells complete a number of events typical of meiosis I including premeiotic DNA synthesis, genetic recombination, and spindle formation. Disjunction of homologous chromosomes, however, fails to occur. Instead, cells proceed through a single meiosis II-like division and form two diploid spores. In this paper, we report the cloning of this essential meiotic gene and an analysis of its transcription during vegetative growth and sporulation. Disruptions of SPO13 in haploid and diploid cells show that it is dispensible for mitotic cell division. Diploids homozygous for the disruptions behave similarly to spo13-1 mutants; they sporulate at wild-type levels and produce two-spored asci. The DNA region complementing spo13-1 encodes two overlapping transcripts, which have the same 3' end but different 5' ends. The major transcript is 400 bases shorter than the larger, less abundant one. The shorter RNA is sufficient to complement the spo13-1 mutation. While both transcripts are undetectable or just barely detectable in vegetative cultures, they each undergo a greater than 70-fold induction early during sporulation, reaching a maximum level about the time of the first meiotic division. In synchronously sporulating populations, the transcripts nearly disappear before the completion of ascus formation. Nonsporulating cells homozygous for the mating-type locus show a small increase in abundance (less than 5% of the increase in sporulating cells) of both transcripts in sporulation medium. These results indicate that expression of the SPO13 gene is developmentally regulated and starvation alone, independent of the genotype at MAT, can trigger initial induction.

Developmental regulation of SPO13, a gene required for separation of homologous chromosomes at meiosis I

1987 ◽  
Vol 7 (4) ◽  
pp. 1425-1435
Author(s):  
H T Wang ◽  
S Frackman ◽  
J Kowalisyn ◽  
R E Esposito ◽  
R Elder
Keyword(s):  
Genetic Recombination ◽  
Developmental Regulation ◽  
Maximum Level ◽  
Mitotic Cell ◽  
Sporulation Medium ◽  
Developmentally Regulated ◽  
Type Locus ◽  
Homologous Chromosomes ◽  
Diploid Cells ◽  
Meiosis I

Previous studies have demonstrated that the SPO13 gene is required for chromosome separation during meiosis I in Saccharomyces cerevisiae. In the presence of the spo13-1 nonsense mutation, MATa/MAT alpha diploid cells complete a number of events typical of meiosis I including premeiotic DNA synthesis, genetic recombination, and spindle formation. Disjunction of homologous chromosomes, however, fails to occur. Instead, cells proceed through a single meiosis II-like division and form two diploid spores. In this paper, we report the cloning of this essential meiotic gene and an analysis of its transcription during vegetative growth and sporulation. Disruptions of SPO13 in haploid and diploid cells show that it is dispensible for mitotic cell division. Diploids homozygous for the disruptions behave similarly to spo13-1 mutants; they sporulate at wild-type levels and produce two-spored asci. The DNA region complementing spo13-1 encodes two overlapping transcripts, which have the same 3' end but different 5' ends. The major transcript is 400 bases shorter than the larger, less abundant one. The shorter RNA is sufficient to complement the spo13-1 mutation. While both transcripts are undetectable or just barely detectable in vegetative cultures, they each undergo a greater than 70-fold induction early during sporulation, reaching a maximum level about the time of the first meiotic division. In synchronously sporulating populations, the transcripts nearly disappear before the completion of ascus formation. Nonsporulating cells homozygous for the mating-type locus show a small increase in abundance (less than 5% of the increase in sporulating cells) of both transcripts in sporulation medium. These results indicate that expression of the SPO13 gene is developmentally regulated and starvation alone, independent of the genotype at MAT, can trigger initial induction.

Regulation of STA1 gene expression by MAT during the life cycle of Saccharomyces cerevisiae

1989 ◽  
Vol 9 (9) ◽  
pp. 3992-3998
Author(s):  
A M Dranginis
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Yeast Cells ◽  
Specific Gene ◽  
Activity Levels ◽  
Sporulation Medium ◽  
Mrna Levels ◽  
Yeast Saccharomyces Cerevisiae ◽  
Type Locus ◽  
Diploid Cells

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.

MATING TYPE AND SPORULATION IN YEAST. II. MEIOSIS, RECOMBINATION, AND RADIATION SENSITIVITY IN AN αα DIPLOID WITH ALTERED SPORULATION CONTROL

Genetics ◽  
1975 ◽  
Vol 80 (1) ◽  
pp. 61-76
Author(s):  
Anita K Hopper ◽  
J Kirsch ◽  
Benjamin D Hall
Keyword(s):  
Mating Type ◽  
Meiotic Recombination ◽  
Meiotic Chromosome ◽  
Preceding Paper ◽  
Radiation Sensitivity ◽  
Sporulation Medium ◽  
Minimal Growth ◽  
Type Locus ◽  
Entire Cell ◽  
Diploid Cells

ABSTRACT In wild-type S. cerevisiae, diploid cells must be heterozygous at the mating-type locus in order to sporulate. In the preceding paper, we described a number of mutants (CSP mutants), isolated from nonsporulating aa and αα parent strains, in which sporulation appeared to be uncoupled from control by mating type. The characterization of one of these mutants (CSP1) is now extended to other processes controlled by mating type. This mutant is indistinguishable from αα cells and unlike aα cells for mating factor production and response, zygote formation, intragenic mitotic recombination, and for X-ray sensitivity. The mutant apparently undergoes a full round of DNA synthesis in sporulation medium, but with delayed kinetics. Only 20% of the cells complete sporulation. Among spores in completed asci, the frequency of both intra- and intergenic recombination is the same as it is for spores produced by aα cells. However, experiments in which cells were shifted from sporulation medium back to minimal growth medium gave a frequency of meiotic recombination between ade2 or leu2 heteroalleles only 25% to 29% as high for CSP1 αα diploid or CSP1  aa disomic cells as for aα diploid or disomic cells. Because the latter result, indicating recombination defectiveness, measured recombinant production in the entire cell population, whereas the result indicating normal recombination sampled only completed spores, we infer that all meiotic recombination events occurring in the population of CSP1 αα cells are concentrated in those few cells which complete sporulation. This high degree of correlation between meiotic recombination and the completion of meiosis and sporulation suggests that recombination may be required for proper meiotic chromosome segregation in yeast just as it appears to be in maize and in Drosophila

scholarly journals Regulation of STA1 gene expression by MAT during the life cycle of Saccharomyces cerevisiae.

1989 ◽  
Vol 9 (9) ◽  
pp. 3992-3998 ◽  
Author(s):  
A M Dranginis
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Yeast Cells ◽  
Specific Gene ◽  
Activity Levels ◽  
Sporulation Medium ◽  
Mrna Levels ◽  
Yeast Saccharomyces Cerevisiae ◽  
Type Locus ◽  
Diploid Cells

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.

scholarly journals A ZIP1 Separation-of-Function Allele Reveals that Meiotic Centromere Pairing Drives Meiotic Segregation of Achiasmate Chromosomes in Budding Yeast

2018 ◽  
Author(s):  
Emily L. Kurdzo ◽  
Hoa H Chuong ◽  
Dean S. Dawson
Keyword(s):  
Chromosome Number ◽  
Single Unit ◽  
Genetic Recombination ◽  
Budding Yeast ◽  
Homologous Chromosomes ◽  
Normal Number ◽  
Relationship Of ◽  
Distinct Features ◽  
The Relationship ◽  
Meiosis I

ABSTRACTIn meiosis I, homologous chromosomes segregate away from each other - the first of two rounds of chromosome segregation that allow the formation of haploid gametes. In prophase I, homologous partners become joined along their length by the synaptonemal complex (SC) and crossovers form between the homologs to generate links called chiasmata. The chiasmata allow the homologs to act as a single unit, called a bivalent, as the chromosomes attach to the microtubules that will ultimately pull them away from each other at anaphase I. Recent studies, in several organisms, have shown that when the SC disassembles at the end of prophase, residual SC proteins remain at the homologous centromeres providing an additional link between the homologs. In budding yeast, this centromere pairing is correlated with improved segregation of the paired partners in anaphase. However, the causal relationship of prophase centromere pairing and subsequent disjunction in anaphase has been difficult to demonstrate as has been the relationship between SC assembly and the assembly of the centromere pairing apparatus. Here, a series of in-frame deletion mutants of the SC component Zip1 were used to address these questions. The identification of separation-of-function alleles that disrupt centromere pairing, but not SC assembly, have made it possible to demonstrate that centromere pairing and SC assembly have mechanistically distinct features and that prophase centromere pairing function of Zip1 drives disjunction of the paired partners in anaphase I.AUTHOR SUMMARYThe generation of gametes requires the completion of a specialized cell división called meiosis. This division is unique in that it produces cells (gametes) with half the normal number of chromosomes (such that when two gametes fuse the normal chromosome number is restored). Chromosome number is reduced in meiosis by following a single round of chromosome duplication with two rounds of segregation. In the first round, meiosis I, homologous chromosomes first pair with each other, then attach to cellular cables, called microtubules, that pull them to opposite sides of the cell. It has long been known that the homologous partners become linked to each other by genetic recombination in a way that helps them behave as a single unit when they attach to the microtubules that will ultimately pull them apart. Recently, it was shown, in budding yeast and other organisms, that homologous partners can also pair at their centromeres. Here we show that this centromere pairing also contributes to proper segregation of the partners away from each other at meiosis I, and demonstrate that one protein involved in this process is able to participate in multiple mechanisms that help homologous chromosomes to pair with each other before being segregated in meiosis I.

scholarly journals Saccharomyces cerevisiae C-Type Cyclin Ume3p/Srb11p Is Required for Efficient Induction and Execution of Meiotic Development

2002 ◽  
Vol 1 (1) ◽  
pp. 66-74 ◽  
Author(s):  
Katrina F. Cooper ◽  
Randy Strich
Keyword(s):  
Spindle Assembly Checkpoint ◽  
Mitotic Cell ◽  
Multiple Roles ◽  
Growth Defect ◽  
Sporulation Medium ◽  
Cyclin Dependent Kinase ◽  
Positive Role ◽  
Efficient Induction ◽  
Bud Growth ◽  
Meiosis I

ABSTRACT The yeast C-type cyclin Ume3p/Srb11p and its cyclin-dependent kinase partner Ume5p/Srb10p repress the transcription of several genes required for meiotic recombination or meiosis I nuclear division. To relieve this repression, Srb11p is destroyed early in meiosis, prior to the first meiotic division. This report identifies two roles for Srb11p in regulating meiotic development. First, SRB11 is required for the normal exit from the mitotic cell cycle prior to meiotic induction. Specifically, mutants lacking SRB11 (srb11Δ) uncouple bud growth from chromosome segregation, producing small buds with nuclei. The bud growth defect is most likely due to the failure of srb11Δ mutants to reestablish polarized actin fibers at the bud tip following exposure to sporulation medium. Second, Srb11p is required for the efficient execution of meiosis I. srb11Δ mutants either exhibited a delay in performing meiosis I and meiosis II or skipped meiosis I entirely. This meiotic defect is not due to the activation of the recombination or spindle assembly checkpoint pathways. However, the expression of several meiotic genes is delayed and reduced in the mutant strains. These results suggest a positive role for Srb10-Srb11p in regulating the transcription program. This model is supported by the finding that overexpression of the meiotic inducer IME2 partially restored the ability of srb11 mutants to perform meiosis I. In conclusion, these findings indicate that Srb11p is required for both entry into and execution of the meiotic program, thus describing multiple roles for a C-type cyclin in the regulation of a developmental pathway.

Meiotic chromosome behavior of Haworthia limifolia

2016 ◽  
Vol 5 (03) ◽  
pp. 4902
Author(s):  
Afrin Nazli ◽  
Kamini Kumar*
Keyword(s):  
Genetic Recombination ◽  
Meiotic Chromosome ◽  
Pollen Sterility ◽  
Meiotic Abnormalities ◽  
Chromosome Behavior ◽  
The Family ◽  
Medicinal Properties ◽  
Fruit Formation ◽  
Meiosis I ◽  
Chromosomal Behaviour

Haworthia limifolia is a xerophytic plant belonging to the family Liliaceae and is indigenous to Africa. It is use extensively for its medicinal properties like antibacterial, antifungal properties and used for the treatment of sores, superficial burns, as a blood purifier and to promote pregnancy in women and cattles. In present investigation chromosomal behaviour of H. limifolia in meiosis was studied. In diplotene stage chiasmata was observed showing the possibilities of genetic recombination. Chromosome clumps were observed in diakinesis indicating sticky nature of chromosomes. Meiotic abnormalities like stickiness, precocious movement, formation of bridges and laggards were also reported in both meiosis I and II. A fairly high percentage of pollen sterility that is 73.41% was recorded resulting in failure of fruit formation. This plant could be designated as facultative apomict (Swanson, 1957) as the only means of reproduction found was asexual or vegetative.

scholarly journals Mating Type in Chlamydomonas Is Specified by mid, the Minus-Dominance Gene

Genetics ◽  
1997 ◽  
Vol 146 (3) ◽  
pp. 859-869 ◽  
Author(s):  
Patrick J Ferris ◽  
Ursula W Goodenough
Keyword(s):  
Transcription Factor ◽  
Mating Type ◽  
Codon Bias ◽  
Leucine Zipper ◽  
Laboratory Strain ◽  
Leucine Zipper Motif ◽  
Type Locus ◽  
Diploid Cells ◽  
Necessary And Sufficient

Diploid cells of Chlamydomonas reinhardtii that are heterozygous at the mating-type locus (mt  +/mt  –) differentiate as minus gametes, a phenomenon known as minus dominance. We report the cloning and characterization of a gene that is necessary and sufficient to exert this minus dominance over the plus differentiation program. The gene, called mid, is located in the rearranged (R) domain of the mt  – locus, and has duplicated and transposed to an autosome in a laboratory strain. The imp11 mt  – mutant, which differentiates as a fusion-incompetent plus gamete, carries a point mutation in mid. Like the fus1 gene in the mt  + locus, mid displays low codon bias compared with other nuclear genes. The mid sequence carries a putative leucine zipper motif, suggesting that it functions as a transcription factor to switch on the minus program and switch off the plus program of gametic differentiation. This is the first sex-determination gene to be characterized in a green organism.

scholarly journals Paired arrangement of kinetochores together with microtubule pivoting and dynamics drive kinetochore capture in meiosis I

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Gheorghe Cojoc ◽  
Ana-Maria Florescu ◽  
Alexander Krull ◽  
Anna H. Klemm ◽  
Nenad Pavin ◽  
...  
Keyword(s):  
Cell Division ◽  
Fission Yeast ◽  
General Feature ◽  
Protein Complexes ◽  
Spindle Pole ◽  
Single Object ◽  
Homologous Chromosomes ◽  
Angular Movement ◽  
Spindle Microtubules ◽  
Meiosis I

Abstract Kinetochores are protein complexes on the chromosomes, whose function as linkers between spindle microtubules and chromosomes is crucial for proper cell division. The mechanisms that facilitate kinetochore capture by microtubules are still unclear. In the present study, we combine experiments and theory to explore the mechanisms of kinetochore capture at the onset of meiosis I in fission yeast. We show that kinetochores on homologous chromosomes move together, microtubules are dynamic and pivot around the spindle pole, and the average capture time is 3–4 minutes. Our theory describes paired kinetochores on homologous chromosomes as a single object, as well as angular movement of microtubules and their dynamics. For the experimentally measured parameters, the model reproduces the measured capture kinetics and shows that the paired configuration of kinetochores accelerates capture, whereas microtubule pivoting and dynamics have a smaller contribution. Kinetochore pairing may be a general feature that increases capture efficiency in meiotic cells.

scholarly journals Identification and developmental regulation of a neuron-specific subunit of cytoplasmic dynein.

1996 ◽  
Vol 7 (2) ◽  
pp. 331-343 ◽  
Author(s):  
K K Pfister ◽  
M W Salata ◽  
J F Dillman ◽  
E Torre ◽  
R J Lye
Keyword(s):  
Axonal Transport ◽  
Developmental Regulation ◽  
Cytoplasmic Dynein ◽  
Retrograde Axonal Transport ◽  
Protein Isoforms ◽  
Cultured Neurons ◽  
Developmentally Regulated ◽  
Time Period ◽  
Intermediate Chains

Cytoplasmic dynein is the microtubule minus-end-directed motor for the retrograde axonal transport of membranous organelles. Because of its similarity to the intermediate chains of flagellar dynein, the 74-kDa intermediate chain (IC74) subunit of dynein is thought to be involved in binding dynein to its membranous organelle cargo. Previously, we identified six isoforms of the IC74 cytoplasmic dynein subunit in the brain. We further demonstrated that cultured glia and neurons expressed different dynein IC74 isoforms and phospho-isoforms. Two isoforms were observed when dynein from glia was analyzed. When dynein from cultured neurons was analyzed, six IC74 isoforms were observed, although the relative amounts of the dynein isoforms from cultured neurons differed from those found in dynein from brain. To better understand the role of the neuronal IC74 isoforms and identify neuron-specific IC74 dynein subunits, the expression of the IC74 protein isoforms and mRNAs of various tissues were compared. As a result of this comparison, the identity of each of the isoform spots observed on two-dimensional gels was correlated with the products of each of the IC74 mRNAs. We also found that between the fifteenth day of gestation (E15) and the fifth day after birth (P5), the relative expression of the IC74 protein isoforms changes, demonstrating that the expression of IC74 isoforms is developmentally regulated in brain. During this time period, there is relatively little change in the abundance of the various IC74 mRNAs. The E15 to P5 time period is one of rapid process extension and initial pattern formation in the rat brain. This result indicates that the changes in neuronal IC74 isoforms coincide with neuronal differentiation, in particular the extension of processes. This suggests a role for the neuronal IC74 isoforms in the establishment or regulation of retrograde axonal transport.

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