Independent synaptic behavior of sister chromatids in Coprinus cinereus

1995 ◽  
Vol 73 (S1) ◽  
pp. 215-220 ◽  
Author(s):  
Patricia J. Pukkila ◽  
Katie B. Shannon ◽  
Cécile Skrzynia
Keyword(s):  
Dna Replication ◽  
Key Words ◽  
Synaptonemal Complex ◽  
Single Unit ◽  
Coprinus Cinereus ◽  
Normal Appearance ◽  
Meiotic Mutants ◽  
Sister Chromatids ◽  
Homologous Alignment

Sister and nonsister chromatids behave in distinct ways during meiosis. We have shown that homologous synapsis does not require the presence of sister chromatids. In mutants that fail to undergo premeiotic DNA replication, synaptonemal complex of normal appearance is observed in diploid nuclei, but not in triploid nuclei. Our results indicate that homologous alignment does not depend on DNA replication. In addition, the differences observed in diploid and triploid nuclei indicate that sister chromatids can exhibit independent synaptic behavior, although ordinarily, they are constrained to act as a single unit. Key words: Coprinus cinereus, meiosis, synaptonemal complex, meiotic mutants, DNA replication, triploid nuclei.

scholarly journals Yeast Meiotic Mutants Proficient for the Induction of Ectopic Recombination

Genetics ◽  
1998 ◽  
Vol 148 (2) ◽  
pp. 581-598
Author(s):  
JoAnne Engebrecht ◽  
Sherie Masse ◽  
Luther Davis ◽  
Kristine Rose ◽  
Therese Kessel
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Meiotic Division ◽  
Ectopic Recombination ◽  
Meiotic Mutants ◽  
Chromosome Synapsis

Abstract A screen was designed to identify Saccharomyces cerevisiae mutants that were defective in meiosis yet proficient for meiotic ectopic recombination in the return-to-growth protocol. Seven mutants alleles were isolated; two are important for chromosome synapsis (RED1, MEK1) and five function independently of recombination (SPO14, GSG1, SPOT8/MUM2, 3, 4). Similar to the spoT8-1 mutant, mum2 deletion strains do not undergo premeiotic DNA synthesis, arrest prior to the first meiotic division and fail to sporulate. Surprisingly, although DNA replication does not occur, mum2 mutants are induced for high levels of ectopic recombination. gsg1 diploids are reduced in their ability to complete premeiotic DNA synthesis and the meiotic divisions, and a small percentage of cells produce spores. mum3 mutants sporulate poorly and the spores produced are inviable. Finally, mum4-1 mutants produce inviable spores. The meiotic/sporulation defects of gsg1, mum2, and mum3 are not relieved by spo11 or spo13 mutations, indicating that the mutant defects are not dependent on the initiation of recombination or completion of both meiotic divisions. In contrast, the spore inviability of the mum4-1 mutant is rescued by the spo13 mutation. The mum4-1 spo13 mutant undergoes a single, predominantly equational division, suggesting that MUM4 functions at or prior to the first meiotic division. Although recombination is variably affected in the gsg1 and mum mutants, we hypothesize that these mutants define genes important for aspects of meiosis not directly related to recombination.

scholarly journals Meiotic mutants tomatoes with desynaptic phenotype

1970 ◽  
pp. 31-36
Author(s):  
T. P. Lisovska
Keyword(s):  
Recombination Frequency ◽  
Low Fertility ◽  
Published Data ◽  
Recessive Character ◽  
Pollen Mother Cells ◽  
Meiotic Mutants ◽  
Sister Chromatids ◽  
Mother Cells ◽  
Meiotic Mutations ◽  
Premature Removal

Aim. A comparative analysis of the cytological manifestation in the meiosis of six meiotic mutants was carried out. Methods. Buds with anthers 2–3 mm long fixed in ethanol: glacial acetic acid in a ratio of 3:1, were stored in 70 % ethanol, stained with acetocarmine. For cytology preparations prepared pressure anthers at various stages of meiosis. Pollen fertility was determined by staining with acetocarmine. Results. Meiotic mutations tomato dsm1, dsm2, dsm3, as1, as5 and asb not affect the vegetative growth of plants, but have low fertility of pollen and number of seeds in the fruit. They are similar cytological manifestation. The beginning of meiosis occurred apparently normal, as violations of premature decay bivalent observed since diplotenе. Chiasma frequencies in pollen mother cells ranged from 8.13 to dsm3 / dsm3 to 6.73 in asb / asb. All investigated mutations revealed monogenic recessive character of inheritance. Mutations as1, as5 and asb and dsm2 are not allelic to each other. The mutation dsm1 appeared allelic to mutations dsm2 and asb. Conclusions. Investigated meiotic mutations failure of chiasma maintenance in the pollen mother cells with varying degrees of desynapsis. Based on the fact that the previously published data did not reveal a reduction in the recombination frequency in marked areas of the genome, we anticipate premature removal of cohesin that hold sister chromatids distal chiasmata.Keywords: meiosis, meiotic mutants, sister chromatids cohesion, premature separation of the bivalents, Lycopersicon esculentum Mill.

Movement and stability analysis of the Beaver Creek landslide, Saskatchewan, Canada

1985 ◽  
Vol 22 (3) ◽  
pp. 277-285 ◽  
Author(s):  
R. T. Yoshida ◽  
J. Krahn
Keyword(s):  
Stability Analysis ◽  
Key Words ◽  
Residual Strength ◽  
Case History ◽  
Single Unit ◽  
Slip Surface ◽  
Friction Angle ◽  
Slide Mass ◽  
History Of ◽  
Residual Values

This paper presents a case history of a multiblock landslide where the blocks move at varying rates along a common horizontal slip surface which follows the contact between stratified drift and underlying till. Movement measurements indicate that the blocks towards the toe move at a higher rate than blocks towards the scarp. Stability analyses show that the entire slide mass can be analyzed as a single unit as opposed to considering each block separately. This finding is compared with the analysis of other multiblock slides. The friction angle mobilized along the horizontal slip surface falls within the range of residual values measured in the laboratory. Key words: landslides, stability, analysis, translational slides, residual strength.

scholarly journals Inverted meiosis: an alternative way of chromosome segregation for reproduction

2020 ◽  
Vol 52 (7) ◽  
pp. 702-707 ◽  
Author(s):  
Wenzhu Li ◽  
Xiangwei He
Keyword(s):  
Dna Replication ◽  
Fission Yeast ◽  
Chromosome Segregation ◽  
Chromosome Structure ◽  
Adaptive Strategy ◽  
Homologous Chromosomes ◽  
Working Model ◽  
Sister Chromatids ◽  
Holocentric Chromosome ◽  
Inverted Order

Abstract Canonical meiosis is characterized by two sequential rounds of nuclear divisions following one round of DNA replication—reductional segregation of homologous chromosomes during the first division and equational segregation of sister chromatids during the second division. Meiosis in an inverted order of two nuclear divisions—inverted meiosis has been observed in several species with holocentromeres as an adaptive strategy to overcome the obstacle in executing a canonical meiosis due to the holocentric chromosome structure. Recent findings of co-existence of inverted and canonical meiosis in two monocentric organisms, human and fission yeast, suggested that inverted meiosis could be common and also lead to the puzzle regarding the mechanistic feasibility for executing two meiosis programs simultaneously. Here, we discuss apparent conflicts for concurrent canonical meiosis and inverted meiosis. Furthermore, we attempt to provide a working model that may be compatible for both forms of meiosis.

PATTERN OF SEGREGATION OF LABELED DNA AT THE CHROMATID LEVEL OF CHROMOSOMES WITH DIFFUSE CENTROMERES

1969 ◽  
Vol 11 (4) ◽  
pp. 928-936 ◽  
Author(s):  
Janet S. R. Nelson
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Sister Chromatid ◽  
Cycle Time ◽  
Full Length ◽  
Sister Chromatids ◽  
Labeling Pattern ◽  
Shoot Meristems

After pulse labeling Luzula purpurea shoot meristems with3H-thymidine, the cell cycle and its subdivisions were determined autoradiographically using the labeled mitoses method. The cycle time was 20 hr. G1 = 4.3 hr; C = 9.5 hr; G2 = 2.9 hr; and M = 3.3 hr. In subsequent experiments seedlings were labeled for 4 to 5 hr, long enough to label the chromosomes' full length, eliminating problems associated with asynchronous DNA replication. The longer labeling period did not alter the cell cycle parameters.Cells were designated as being in the first or second division after labeling by the time from the midpoint of the labeling period. Seedlings were placed in 0.1% cycloheximide solution to cause sister chromatids in metaphase cells to separate from each other. Autoradiographs were then made to determine segregation of labeled DNA at the chromatid level. At the first division after labeling all chromatids appeared to be labeled. At the second division after labeling with 3H-thymidine the labeling pattern was consistent with semiconservative segregation of labeled DNA and with sister chromatid exchange.These results are discussed in relation to cytological and photometric studies on chromosome strandedness in Luzula and in other organisms with chromosomes with diffuse centromeres.

scholarly journals Meiotic cohesin REC8 marks the axial elements of rat synaptonemal complexes before cohesins SMC1β and SMC3

2003 ◽  
Vol 160 (5) ◽  
pp. 657-670 ◽  
Author(s):  
Maureen Eijpe ◽  
Hildo Offenberg ◽  
Rolf Jessberger ◽  
Ekaterina Revenkova ◽  
Christa Heyting
Keyword(s):  
Synaptonemal Complex ◽  
Sister Chromatid ◽  
Meiotic Prophase ◽  
S Phase ◽  
Synaptonemal Complexes ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Axial Element ◽  
Striking Contrast ◽  
Metaphase I

In meiotic prophase, the sister chromatids of each chromosome develop a common axial element (AE) that is integrated into the synaptonemal complex (SC). We analyzed the incorporation of sister chromatid cohesion proteins (cohesins) and other AE components into AEs. Meiotic cohesin REC8 appeared shortly before premeiotic S phase in the nucleus and formed AE-like structures (REC8-AEs) from premeiotic S phase on. Subsequently, meiotic cohesin SMC1β, cohesin SMC3, and AE proteins SCP2 and SCP3 formed dots along REC8-AEs, which extended and fused until they lined REC8-AEs along their length. In metaphase I, SMC1β, SMC3, SCP2, and SCP3 disappeared from the chromosome arms and accumulated around the centromeres, where they stayed until anaphase II. In striking contrast, REC8 persisted along the chromosome arms until anaphase I and near the centromeres until anaphase II. We propose that REC8 provides a basis for AE formation and that the first steps in AE assembly do not require SMC1β, SMC3, SCP2, and SCP3. Furthermore, SMC1β, SMC3, SCP2, and SCP3 cannot provide arm cohesion during metaphase I. We propose that REC8 then provides cohesion. RAD51 and/or DMC1 coimmunoprecipitates with REC8, suggesting that REC8 may also provide a basis for assembly of recombination complexes.

An ultrastructural pachytene karyotype for Puccinia graminis f.sp. tritici

1992 ◽  
Vol 70 (2) ◽  
pp. 401-413 ◽  
Author(s):  
E. W. A. Boehm ◽  
J. C. Wenstrom ◽  
D. J. McLaughlin ◽  
L. J. Szabo ◽  
A. P. Roelfs ◽  
...  
Keyword(s):  
Key Words ◽  
Synaptonemal Complex ◽  
Electron Micrographs ◽  
Three Dimensional ◽  
Chromosome Length ◽  
Epifluorescence Microscopy ◽  
Puccinia Graminis ◽  
Morphological Markers ◽  
Dimensional Reconstruction ◽  
Pachytene Karyotype

The karyotype for Puccinia graminis f.sp. tritici was determined from reconstructions of electron micrographs of serially sectioned pachytene nuclei. Epifluorescence microscopy was used to select DAPI-stained, pachytene nuclei in teliospore protoplasts from which walls were mechanically removed. Selection increased the probability that pachytene nuclei could be found in the absence of morphological markers. Six pachytene nuclei were reconstructed from four geographically disparate North American isolates. One nucleus was used to obtain a computer-enhanced, three-dimensional reconstruction that could be rendered as rotatable colorized stereo pairs. A karyotype of n = 18 was determined for all six nuclei. The 18 bivalents varied only slightly in size, each ranging from 3.0 to 8.8% of the total length of the genome. Total genomic lengths also proved highly comparable among isolates. Centromeres were not found, precluding use of the centromeric index as an aid in karyotyping. Only the nucleolus-associated bivalent could be cross-correlated among the six reconstructed nuclei. Heterogeneity in length among, but not within, isolates was observed for this bivalent, suggesting that chromosome length may be polymorphic in P. graminis f.sp. tritici, despite a constant total number of chromosomes. Key words: chromosomes, heterobasidiomycete, synaptonemal complex, Uredinales.

scholarly journals Dynamics of sister chromatids through the cell cycle: Together and apart

2018 ◽  
Vol 217 (6) ◽  
pp. 1887-1889 ◽  
Author(s):  
Motoko Takahashi ◽  
Toru Hirota
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Sister Chromatid ◽  
Fundamental Question ◽  
Live Cells ◽  
Sister Chromatids ◽  
Cell Biol

When and how sister chromatid resolution occurs after DNA replication is a fundamental question. Stanyte et al. (2018. J. Cell Biol. https://doi.org/10.1083/jcb.201801157) used CRISPR/Cas9 technology to label and track genomic loci in live cells throughout the cell cycle, shedding light on how replication is linked to mitotic sister chromatid organization.

scholarly journals Multivalent interaction of ESCO2 with the replication machinery is required for cohesion

2019 ◽  
Author(s):  
Dawn Bender ◽  
Eulália Maria Lima Da Silva ◽  
Jingrong Chen ◽  
Annelise Poss ◽  
Lauren Gawey ◽  
...  
Keyword(s):  
Cell Division ◽  
Dna Replication ◽  
Cohesin Complex ◽  
Replication Machinery ◽  
Replicative Helicase ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Mcm Helicase ◽  
N Terminus ◽  
Processivity Factor

AbstractThe tethering together of sister chromatids by the cohesin complex ensures their accurate alignment and segregation during cell division. In vertebrates, the establishment of cohesion between sister chromatids requires the activity of the ESCO2 acetyltransferase, which modifies the Smc3 subunit of cohesin. It was shown recently that ESCO2 promotes cohesion through interaction with the MCM replicative helicase. However, ESCO2 does not significantly colocalize with the MCM helicase, suggesting there may be additional interactions that are important for ESCO2 function. Here we show that ESCO2 is recruited to replication factories, the sites of DNA replication. We show that ESCO2 contains multiple conserved PCNA-interaction motifs in its N-terminus, and that each of these motifs are essential to ESCO2’s ability to establish sister chromatid cohesion. We propose that multiple PCNA interaction motifs embedded in a largely flexible and disordered region of the protein underlie the ability of ESCO2 to establish cohesion between sister chromatids precisely as they are born during DNA replication.SummaryCohesin modification by the ESCO2 acetyltransferase is required for cohesion between sister chromatids. Here we identify multiple motifs in ESCO2 that mediate its interaction with the replication processivity factor PCNA, and show that their mutation abrogates the ability of ESCO2 to ensure cohesion.

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