scholarly journals Meiotic disjunction of homologs in Saccharomyces cerevisiae is directed by pairing and recombination of the chromosome arms but not by pairing of the centromeres.

Genetics ◽  
1988 ◽  
Vol 119 (2) ◽  
pp. 273-287
Author(s):  
R T Surosky ◽  
B K Tye
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Meiotic Chromosome ◽  
Chromosomal Rearrangements ◽  
Normal Chromosome ◽  
Telocentric Chromosome ◽  
Meiotic Chromosomes ◽  
Chromosome Recombination ◽  
Left And Right ◽  
Chromosome Iii

Abstract We explored the behavior of meiotic chromosomes in Saccharomyces cerevisiae by examining the effects of chromosomal rearrangements on the pattern of disjunction and recombination of chromosome III during meiosis. The segregation of deletion chromosomes lacking part or all (telocentric) of one arm was analyzed in the presence of one or two copies of a normal chromosome III. In strains containing one normal and any one deletion chromosome, the two chromosomes disjoined in most meioses. In strains with one normal chromosome and both a left and right arm telocentric chromosome, the two telocentrics preferentially disjoined from the normal chromosome. Homology on one arm was sufficient to direct chromosome disjunction, and two chromosomes could be directed to disjoin from a third. In strains containing one deletion chromosome and two normal chromosomes, the two normal chromosomes preferentially disjoined, but in 4-7% of the tetrads the normal chromosomes cosegregated, disjoining from the deletion chromosome. Recombination between the two normal chromosomes or between the deletion chromosome and a normal chromosome increased the probability that these chromosomes would disjoin, although cosegregation of recombinants was observed. Finally, we observed that a derivative of chromosome III in which the centromeric region was deleted and CEN5 was integrated at another site on the chromosome disjoined from a normal chromosome III with fidelity. These studies demonstrate that it is not pairing of the centromeres, but pairing and recombination along the arms of the homologs, that directs meiotic chromosome segregation.

scholarly journals Meiotic Chromosome Segregation in Triploid Strains of Saccharomyces cerevisiae

Genetics ◽  
2010 ◽  
Vol 186 (2) ◽  
pp. 537-550 ◽  
Author(s):  
Jordan St. Charles ◽  
Monica L. Hamilton ◽  
Thomas D. Petes
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Meiotic Chromosome

scholarly journals Construction and behavior of circularly permuted and telocentric chromosomes in Saccharomyces cerevisiae.

1986 ◽  
Vol 6 (9) ◽  
pp. 3166-3172 ◽  
Author(s):  
A W Murray ◽  
J W Szostak
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Very High Frequency ◽  
Telocentric Chromosome ◽  
Artificial Chromosomes ◽  
Telocentric Chromosomes ◽  
Novel Variants ◽  
Chromosome Iii ◽  
And Behavior ◽  
Mitosis And Meiosis ◽  
Very High

We developed techniques that allow us to construct novel variants of Saccharomyces cerevisiae chromosomes. These modified chromosomes have precisely determined structures. A metacentric derivative of chromosome III which lacks the telomere-associated X and Y' elements, which are found at the telomeres of most yeast chromosomes, behaves normally in both mitosis and meiosis. We made a circularly permuted telocentric version of yeast chromosome III whose closest telomere was 33 kilobases from the centromere. This telocentric chromosome was lost at a frequency of 1.6 X 10(-5) per cell compared with a frequency of 4.0 X 10(-6) for the natural metacentric version of chromosome III. An extremely telocentric chromosome whose closet telomere was only 3.5 kilobases from the centromere was lost at a frequency of 6.0 X 10(-5). The mitotic stability of telocentric chromosomes shows that the very high frequency of nondisjunction observed for short linear artificial chromosomes is not due to inadequate centromere-telomere separation.

scholarly journals Nucleosome depletion alters the chromatin structure of Saccharomyces cerevisiae centromeres.

1990 ◽  
Vol 10 (11) ◽  
pp. 5721-5727 ◽  
Author(s):  
M J Saunders ◽  
E Yeh ◽  
M Grunstein ◽  
K Bloom
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Mutational Analysis ◽  
Base Pairs ◽  
Centromere Function ◽  
Nuclease Digestion ◽  
Dna Elements ◽  
Chromosome Iii ◽  
Sequence Requirements

Saccharomyces cerevisiae centromeric DNA is packaged into a highly nuclease-resistant chromatin core of approximately 200 base pairs of DNA. The structure of the centromere in chromosome III is somewhat larger than a 160-base-pair nucleosomal core and encompasses the conserved centromere DNA elements (CDE I, II, and III). Extensive mutational analysis has revealed the sequence requirements for centromere function. Mutations affecting the segregation properties of centromeres also exhibit altered chromatin structures in vivo. Thus the structure, as delineated by nuclease digestion, correlated with functional centromeres. We have determined the contribution of histone proteins to this unique structural organization. Nucleosome depletion by repression of either histone H2B or H4 rendered the cell incapable of chromosome segregation. Histone repression resulted in increased nuclease sensitivity of centromere DNA, with up to 40% of CEN3 DNA molecules becoming accessible to nucleolytic attack. Nucleosome depletion also resulted in an alteration in the distribution of nuclease cutting sites in the DNA surrounding CEN3. These data provide the first indication that authentic nucleosomal subunits flank the centromere and suggest that nucleosomes may be the central core of the centromere itself.

Structural Analysis of Aberrant Chromosomes That Occur Spontaneously in Diploid Saccharomyces cerevisiae: Retrotransposon Ty1 Plays a Crucial Role in Chromosomal Rearrangements

Genetics ◽  
2002 ◽  
Vol 160 (1) ◽  
pp. 97-110
Author(s):  
Keiko Umezu ◽  
Mina Hiraoka ◽  
Masaaki Mori ◽  
Hisaji Maki
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Structural Analysis ◽  
Molecular Mechanisms ◽  
Chromosomal Rearrangements ◽  
Yeast Cells ◽  
Yeast Genome ◽  
Complex Construction ◽  
Functional Inactivation ◽  
Chromosome Iii ◽  
The Right

Abstract The structural analysis of aberrant chromosomes is important for our understanding of the molecular mechanisms underlying chromosomal rearrangements. We have identified a number of diploid Saccharomyces cerevisiae clones that have undergone loss of heterozygosity (LOH) leading to functional inactivation of the hemizygous URA3 marker placed on the right arm of chromosome III. Aberrant-sized chromosomes derived from chromosome III were detected in ~8% of LOH clones. Here, we have analyzed the structure of the aberrant chromosomes in 45 LOH clones with a PCR-based method that determines the ploidy of a series of loci on chromosome III. The alterations included various deletions and amplifications. Sequencing of the junctions revealed that all the breakpoints had been made within repeat sequences in the yeast genome, namely, MAT-HMR, which resulted in intrachromosomal deletion, and retrotransposon Ty1 elements, which were involved in various translocations. Although the translocations involved different breakpoints on different chromosomes, all breakpoints were exclusively within Ty1 elements. Some of the resulting Ty1 elements left at the breakpoints had a complex construction that indicated the involvement of other Ty1 elements not present at the parental breakpoints. These indicate that Ty1 elements are crucially involved in the generation of chromosomal rearrangements in diploid yeast cells.

scholarly journals Meiotic chromosome pairing in triploid and tetraploid Saccharomyces cerevisiae.

Genetics ◽  
1995 ◽  
Vol 139 (4) ◽  
pp. 1511-1520 ◽  
Author(s):  
J Loidl
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Complex Formation ◽  
Chromosome Segregation ◽  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Low Frequency ◽  
Spore Viability ◽  
Homologous Chromosomes ◽  
Meiotic Chromosome Pairing ◽  
Synaptonemal Complex Formation

Abstract Meiotic chromosome pairing in isogenic triploid and tetraploid strains of yeast and the consequences of polyploidy on meiotic chromosome segregation are studied. Synaptonemal complex formation at pachytene was found to be different in the triploid and in the tetraploid. In the triploid, triple-synapsis, that is, the connection of three homologues at a given site, is common. It can even extend all the way along the chromosomes. In the tetraploid, homologous chromosomes mostly come in pairs of synapsed bivalents. Multiple synapsis, that is, synapsis of more than two homologues in one and the same region, was virtually absent in the tetraploid. About five quadrivalents per cell occurred due to the switching of pairing partners. From the frequency of pairing partner switches it can be deduced that in most chromosomes synapsis is initiated primarily at one end, occasionally at both ends and rarely at an additional intercalary position. In contrast to a considerably reduced spore viability (approximately 40%) in the triploid, spore viability is only mildly affected in the tetraploid. The good spore viability is presumably due to the low frequency of quadrivalents and to the highly regular 2:2 segregation of the few quadrivalents that do occur. Occasionally, however, quadrivalents appear to be subject to 3:1 nondisjunction that leads to spore death in the second generation.

scholarly journals Nucleosome depletion alters the chromatin structure of Saccharomyces cerevisiae centromeres

1990 ◽  
Vol 10 (11) ◽  
pp. 5721-5727
Author(s):  
M J Saunders ◽  
E Yeh ◽  
M Grunstein ◽  
K Bloom
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Mutational Analysis ◽  
Base Pairs ◽  
Centromere Function ◽  
Nuclease Digestion ◽  
Dna Elements ◽  
Chromosome Iii ◽  
Sequence Requirements

Saccharomyces cerevisiae centromeric DNA is packaged into a highly nuclease-resistant chromatin core of approximately 200 base pairs of DNA. The structure of the centromere in chromosome III is somewhat larger than a 160-base-pair nucleosomal core and encompasses the conserved centromere DNA elements (CDE I, II, and III). Extensive mutational analysis has revealed the sequence requirements for centromere function. Mutations affecting the segregation properties of centromeres also exhibit altered chromatin structures in vivo. Thus the structure, as delineated by nuclease digestion, correlated with functional centromeres. We have determined the contribution of histone proteins to this unique structural organization. Nucleosome depletion by repression of either histone H2B or H4 rendered the cell incapable of chromosome segregation. Histone repression resulted in increased nuclease sensitivity of centromere DNA, with up to 40% of CEN3 DNA molecules becoming accessible to nucleolytic attack. Nucleosome depletion also resulted in an alteration in the distribution of nuclease cutting sites in the DNA surrounding CEN3. These data provide the first indication that authentic nucleosomal subunits flank the centromere and suggest that nucleosomes may be the central core of the centromere itself.

scholarly journals Mutations in CEN3 cause aberrant chromosome segregation during meiosis in Saccharomyces cerevisiae.

Genetics ◽  
1989 ◽  
Vol 121 (3) ◽  
pp. 477-489
Author(s):  
A Gaudet ◽  
M Fitzgerald-Hayes
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Point Mutations ◽  
High Rate ◽  
Wild Type ◽  
Rich Region ◽  
Aberrant Chromosome ◽  
Chromosome Iii ◽  
Diploid Cells ◽  
Sequence Characteristics

Abstract We investigated the structural requirements of the centromere from chromosome III (CEN3) of Saccharomyces cerevisiae by analyzing the ability of chromosomes with CEN3 mutations to segregate properly during meiosis. We analyzed diploid cells in which one or both copies of chromosome III carry a mutant centromere in place of the wild-type centromere and found that some alterations in the length, base composition and primary sequence characteristics of the central A+T-rich region (CDE II) of the centromere had a significant effect on the ability of the chromosome to segregate properly through meiosis. Chromosomes containing mutations which delete a portion of CDE II showed a high rate of premature disjunction at meiosis I. Chromosomes containing point mutations in CDE I or lacking CDE I appeared to segregate properly through meiosis; however, plasmids carrying centromeres with CDE I completely deleted showed an increased frequency of segregation to nonsister spores.

scholarly journals Variation in Crossover Frequencies Perturb Crossover Assurance Without Affecting Meiotic Chromosome Segregation in Saccharomyces cerevisiae

Genetics ◽  
2014 ◽  
Vol 199 (2) ◽  
pp. 399-412 ◽  
Author(s):  
Gurukripa N. Krishnaprasad ◽  
Mayakonda T. Anand ◽  
Gen Lin ◽  
Manu M. Tekkedil ◽  
Lars M. Steinmetz ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Meiotic Chromosome

scholarly journals Eco1-dependent cohesin acetylation anchors chromatin loops and cohesion to define functional meiotic chromosome domains

2021 ◽  
Author(s):  
Rachael E Barton ◽  
Lucia F Massari ◽  
Daniel Robertson ◽  
Adele L Marston
Keyword(s):  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Meiotic Chromosome ◽  
Chromatin Loops ◽  
Meiotic Chromosomes ◽  
Sister Chromatids ◽  
Gamete Formation ◽  
Chromosome Domains ◽  
Chromatid Cohesion ◽  
Cohesin Subunit

Cohesin organizes the genome by forming intra-chromosomal loops and inter-sister chromatid linkages. During gamete formation by meiosis, chromosomes are reshaped to support crossover recombination and two consecutive rounds of chromosome segregation. Here we show that Eco1 acetyltransferase positions both chromatin loops and sister chromatid cohesion to organize meiotic chromosomes into functional domains in budding yeast. Eco1 acetylates the Smc3 cohesin subunit in meiotic S phase to establish chromatin boundaries, independently of DNA replication. Boundary formation by Eco1 is critical for prophase exit and for the maintenance of cohesion until meiosis II, but is independent of the ability of Eco1 to antagonize the cohesin-release factor, Wpl1. Conversely, prevention of cohesin release by Wpl1 is essential for centromeric cohesion, kinetochore monoorientation and co-segregation of sister chromatids in meiosis I. Our findings establish Eco1 as a key determinant of chromatin boundaries and cohesion positioning, revealing how local chromosome structuring directs genome transmission into gametes.

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