scholarly journals Three-Dimensional Microscopy of the Rad51 Recombination Protein during Meiotic Prophase

1999 ◽  
Vol 11 (5) ◽  
pp. 809-824 ◽  
Author(s):  
Amie E. Franklin ◽  
John McElver ◽  
Ivana Sunjevaric ◽  
Rodney Rothstein ◽  
Ben Bowen ◽  
...  
Keyword(s):  
Meiotic Prophase ◽  
Three Dimensional ◽  
Recombination Protein

Three-Dimensional Microscopy of the Rad51 Recombination Protein during Meiotic Prophase

1999 ◽  
Vol 11 (5) ◽  
pp. 809 ◽  
Author(s):  
Amie E. Franklin ◽  
John McElver ◽  
Ivana Sunjevaric ◽  
Rodney Rothstein ◽  
Ben Bowen ◽  
...  
Keyword(s):  
Meiotic Prophase ◽  
Three Dimensional ◽  
Recombination Protein

scholarly journals Identification of a meiosis-specific chromosome movement pattern induced by persistent DNA damage

2020 ◽  
Author(s):  
Daniel León-Periñán ◽  
Alfonso Fernández-Álvarez
Keyword(s):  
Dna Damage ◽  
Meiotic Prophase ◽  
Meiotic Chromosome ◽  
Three Dimensional ◽  
Model Organism ◽  
Movement Pattern ◽  
Time Lapse ◽  
Chromosome Movement ◽  
Nuclear Movement ◽  
Chromosome Associations

ABSTRACTAs one of the main events occurring during meiotic prophase, the dynamics of meiotic chromosome movement is not yet well understood. Currently, although it is well-established that chromosome movement takes an important role during meiotic recombination promoting the pairing between homologous chromosomes and avoiding excessive chromosome associations, it is mostly unclear whether those movements follow a particular fixed pattern, or are stochastically distributed. Using Schizosaccharomyces pombe as a model organism, which exhibits dramatic meiotic nuclear oscillations, we have developed a computationally automatized statistical analysis of three-dimensional time-lapse fluorescence information in order to characterize nuclear trajectories and morphological patterns during meiotic prophase. This approach allowed us to identify a patterned oscillatory microvariation during the meiotic nuclear motion. Additionally, we showed evidence suggesting that this unexpected oscillatory motif might be due to the detection of persistent DNA damage during the nuclear movement, supporting how the nucleus also regulates its oscillations. Our computationally automatized tool will be useful for the identification of new patterns of nuclear oscillations during gametogenesis.

Elimination of multivalents during meiotic prophase in Scilla autumnalis. I. Diploid and triploid

Genome ◽  
1988 ◽  
Vol 30 (6) ◽  
pp. 930-939 ◽  
Author(s):  
J. White ◽  
G. Jenkins ◽  
J. S. Parker
Keyword(s):  
Meiotic Prophase ◽  
Three Dimensional ◽  
Low Frequency ◽  
Chiasma Formation ◽  
Root Tip ◽  
Synaptonemal Complexes ◽  
Dimensional Reconstruction ◽  
Scilla Autumnalis ◽  
Surface Spreading ◽  
Pairing Behaviour

The ultrastructure and pairing behaviour of the chromosomes of two diploid cytotypes and a triploid of Scilla autumnalis were investigated using the techniques of three-dimensional reconstruction from serial electron micrographs and whole-mount surface spreading of synaptonemal complexes. The diploids, designated AA and B7B7, have karyotypes that are virtually identical in appearance at mitotic metaphase but differ in length by 47% and in DNA content by 66%. All the chromosomes were identified during meiotic prophase in both diploids, enabling construction of accurate karyotypes, which were the same as those derived from root tip metaphases. Chromosome pairing was largely regular with very few structural chromosome rearrangements. These two observations permitted confident interpretations of multivalent configurations observed in polyploids containing multiples of the A and B7 genomes. In the triploid (AB7B7) during meiotic prophase lateral components are associated in groups of three, either as trivalents with several exchanges of pairing partners, or as bivalents and univalents in close alignment. The overall difference in length between A and B7 chromosomes is close to expected, but varies to some degree depending on the extent of pairing between the two chromosome types. Most of the synaptonemal complexes between A and B7 homoeologues are ineffective in terms of chiasma formation, as revealed by the low frequency of multivalents and heteromorphic bivalents at metaphase I. In other words, there is an elimination of multivalents during meiotic prophase in the triploid.Key words: Scilla autumnalis, synaptonemal complex, multivalents, elimination.

scholarly journals Recombination protein Tid1p controls resolution of cohesin-dependent linkages in meiosis in Saccharomyces cerevisiae

2005 ◽  
Vol 171 (2) ◽  
pp. 241-253 ◽  
Author(s):  
Anna V. Kateneva ◽  
Anton A. Konovchenko ◽  
Vincent Guacci ◽  
Michael E. Dresser
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Meiotic Prophase ◽  
Primary Defect ◽  
Homologous Chromosomes ◽  
Sister Chromatids ◽  
Recombination Protein ◽  
Chromatid Cohesion ◽  
Recombination Repair ◽  
Established Role

Sister chromatid cohesion and interhomologue recombination are coordinated to promote the segregation of homologous chromosomes instead of sister chromatids at the first meiotic division. During meiotic prophase in Saccharomyces cerevisiae, the meiosis-specific cohesin Rec8p localizes along chromosome axes and mediates most of the cohesion. The mitotic cohesin Mcd1p/Scc1p localizes to discrete spots along chromosome arms, and its function is not clear. In cells lacking Tid1p, which is a member of the SWI2/SNF2 family of helicase-like proteins that are involved in chromatin remodeling, Mcd1p and Rec8p persist abnormally through both meiotic divisions, and chromosome segregation fails in the majority of cells. Genetic results indicate that the primary defect in these cells is a failure to resolve Mcd1p-mediated connections. Tid1p interacts with recombination enzymes Dmc1p and Rad51p and has an established role in recombination repair. We propose that Tid1p remodels Mcd1p-mediated cohesion early in meiotic prophase to facilitate interhomologue recombination and the subsequent segregation of homologous chromosomes.

scholarly journals High Temporal Resolution 3D Live-Cell Imaging of Budding Yeast Meiosis Defines Discontinuous Actin/Telomere-Mediated Chromosome Motion, Correlated Nuclear Envelope Deformation and Actin Filament Dynamics

2021 ◽  
Vol 9 ◽  
Author(s):  
Tadasu Nozaki ◽  
Frederick Chang ◽  
Beth Weiner ◽  
Nancy Kleckner
Keyword(s):  
Nuclear Envelope ◽  
Temporal Resolution ◽  
Meiotic Prophase ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Budding Yeast ◽  
Three Dimensional ◽  
Live Cell ◽  
High Temporal Resolution ◽  
Homolog Pairing

Chromosome movement is prominent at mid-meiotic prophase and is proposed to enhance the efficiency and/or stringency of homolog pairing and/or to help prevent or resolve topological entanglements. Here, we combine fluorescent repressor operator system (FROS) labeling with three-dimensional (3D) live-cell imaging at high spatio-temporal resolution to define the detailed kinetics of mid-meiotic prophase motion for a single telomere-proximal locus in budding yeast. Telomere motions can be grouped into three general categories: (i) pauses, in which the telomere “jiggles in place”; (ii) rapid, straight/curvilinear motion which reflects Myo2/actin-mediated transport of the monitored telomere; and (iii) slower directional motions, most of which likely reflect indirectly promoted motion of the monitored telomere in coordination with actin-mediated motion of an unmarked telomere. These and other findings highlight the importance of dynamic assembly/disassembly of telomere/LINC/actin ensembles and also suggest important roles for nuclear envelope deformations promoted by actin-mediated telomere/LINC movement. The presented low-SNR (signal-to-noise ratio) imaging methodology provides opportunities for future exploration of homolog pairing and related phenomena.

scholarly journals Genome-wide variability in recombination activity is associated with meiotic chromatin organization

2021 ◽  
Author(s):  
Xiaofan Jin ◽  
Geoff Fudenberg ◽  
Katherine S Pollard
Keyword(s):  
Meiotic Prophase ◽  
Three Dimensional ◽  
Strand Break ◽  
Early Prophase ◽  
Recombination Activity ◽  
Homologous Chromosomes ◽  
Genome Wide ◽  
Wide Variability ◽  
Genomic Regions ◽  
Negative Health Outcomes

Background: Recombination enables reciprocal exchange of genomic information between parental chromosomes and successful segregation of homologous chromosomes during meiosis. Errors in this process lead to negative health outcomes, while variability in recombination rate affects genome evolution. In mammals, most crossovers occur in hotspots defined by PRDM9 motifs, though PRDM9 binding sites are not all equally hot. We hypothesize that dynamic patterns of meiotic genome folding are linked to recombination activity. Results: We apply an integrative bioinformatics approach to analyze how three-dimensional (3D) chromosomal organization during meiosis relates to rates of double-strand-break (DSB) and crossover formation at PRDM9 hotspots. We show that active, spatially accessible genomic regions during meiotic prophase are associated with DSB-favoured hotspots, which further adopt a transient locally active configuration in early prophase. Conversely, crossover formation is depleted among DSBs in spatially accessible regions during meiotic prophase, particularly within gene bodies. We also find evidence that active chromatin regions have smaller average loop sizes in mammalian meiosis. Collectively, these findings establish that differences in chromatin architecture along chromosomal axes are associated with variable recombination activity. Conclusions: We propose an updated framework describing how 3D organization of brush-loop chromosomes during meiosis may modulate recombination.

The orbit of Pluto over a long interval of time

1966 ◽  
Vol 25 ◽  
pp. 227-229 ◽  
Author(s):  
D. Brouwer
Keyword(s):  
Periodic Orbit ◽  
Numerical Integration ◽  
Restricted Problem ◽  
Three Dimensional ◽  
The Third ◽  
Circular Restricted Problem ◽  
Resonance Relation

The paper presents a summary of the results obtained by C. J. Cohen and E. C. Hubbard, who established by numerical integration that a resonance relation exists between the orbits of Neptune and Pluto. The problem may be explored further by approximating the motion of Pluto by that of a particle with negligible mass in the three-dimensional (circular) restricted problem. The mass of Pluto and the eccentricity of Neptune's orbit are ignored in this approximation. Significant features of the problem appear to be the presence of two critical arguments and the possibility that the orbit may be related to a periodic orbit of the third kind.

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