scholarly journals PAIR3, an axis-associated protein, is essential for the recruitment of recombination elements onto meiotic chromosomes in rice

2011 ◽  
Vol 22 (1) ◽  
pp. 12-19 ◽  
Author(s):  
Kejian Wang ◽  
Mo Wang ◽  
Ding Tang ◽  
Yi Shen ◽  
Baoxiang Qin ◽  
...  
Keyword(s):  
Synaptonemal Complex ◽  
Central Element ◽  
Dependent Manner ◽  
Homologous Pairing ◽  
Homologous Chromosomes ◽  
Prophase I ◽  
Meiotic Chromosomes

During meiosis, the paired homologous chromosomes are tightly held together by the synaptonemal complex (SC). This complex consists of two parallel axial/lateral elements (AEs/LEs) and one central element. Here, we observed that PAIR3 localized to the chromosome core during prophase I and associated with both unsynapsed AEs and synapsed LEs. Analyses of the severe pair3 mutant demonstrated that PAIR3 was essential for bouquet formation, homologous pairing and normal recombination, and SC assembly. In addition, we showed that although PAIR3 was not required for the initial recruitment of PAIR2, it was required for the proper association of PAIR2 with chromosomes. Dual immunostaining revealed that PAIR3 highly colocalized with REC8. Moreover, studies using a rec8 mutant indicated that PAIR3 localized to chromosomes in a REC8-dependent manner.

scholarly journals Micromanipulation of prophase I chromosomes from mouse spermatocytes reveals high stiffness and gel-like chromatin organization

2020 ◽  
Author(s):  
Ronald Biggs ◽  
Ning Liu ◽  
Yiheng Peng ◽  
John F. Marko ◽  
Huanyu Qiao
Keyword(s):  
Meiotic Prophase ◽  
Central Element ◽  
Critical Event ◽  
Mitotic Chromosomes ◽  
Large Protein ◽  
Homologous Chromosomes ◽  
Prophase I ◽  
Meiotic Prophase I ◽  
Meiotic Chromosomes ◽  
Genetic Mutants

Meiosis produces four haploid cells after two successive divisions in sexually reproducing organisms. A critical event during meiosis is construction of the synaptonemal complex (SC), a large, protein-based bridge that physically links homologous chromosomes. The SC facilitates meiotic recombination, chromosome compaction, and the eventual separation of homologous chromosomes at metaphase I. We present experiments directly measuring physical properties of captured mammalian meiotic prophase I chromosomes. Mouse meiotic chromosomes are about ten-fold stiffer than somatic mitotic chromosomes, even for genetic mutants lacking SYCP1, the central element of the SC. Meiotic chromosomes dissolve when treated with nucleases, but only weaken when treated with proteases, suggesting that the SC is not rigidly connected, and that meiotic prophase I chromosomes are a gel meshwork of chromatin, similar to mitotic chromosomes. These results are consistent with a liquid- or liquid-crystal SC, but with SC-chromatin stiff enough to mechanically drive crossover interference.

scholarly journals Micromanipulation of prophase I chromosomes from mouse spermatocytes reveals high stiffness and gel-like chromatin organization

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Ronald J. Biggs ◽  
Ning Liu ◽  
Yiheng Peng ◽  
John F. Marko ◽  
Huanyu Qiao
Keyword(s):  
Meiotic Prophase ◽  
Central Element ◽  
Critical Event ◽  
Mitotic Chromosomes ◽  
Large Protein ◽  
Homologous Chromosomes ◽  
Prophase I ◽  
Meiotic Prophase I ◽  
Meiotic Chromosomes ◽  
Genetic Mutants

Abstract Meiosis produces four haploid cells after two successive divisions in sexually reproducing organisms. A critical event during meiosis is construction of the synaptonemal complex (SC), a large, protein-based bridge that physically links homologous chromosomes. The SC facilitates meiotic recombination, chromosome compaction, and the eventual separation of homologous chromosomes at metaphase I. We present experiments directly measuring physical properties of captured mammalian meiotic prophase I chromosomes. Mouse meiotic chromosomes are about ten-fold stiffer than somatic mitotic chromosomes, even for genetic mutants lacking SYCP1, the central element of the SC. Meiotic chromosomes dissolve when treated with nucleases, but only weaken when treated with proteases, suggesting that the SC is not rigidly connected, and that meiotic prophase I chromosomes are a gel meshwork of chromatin, similar to mitotic chromosomes. These results are consistent with a liquid- or liquid-crystal SC, but with SC-chromatin stiff enough to mechanically drive crossover interference.

scholarly journals akirin is required for diakinesis bivalent structure and synaptonemal complex disassembly at meiotic prophase I

2013 ◽  
Vol 24 (7) ◽  
pp. 1053-1067 ◽  
Author(s):  
Amy M. Clemons ◽  
Heather M. Brockway ◽  
Yizhi Yin ◽  
Bhavatharini Kasinathan ◽  
Yaron S. Butterfield ◽  
...  
Keyword(s):  
Synaptonemal Complex ◽  
Meiotic Prophase ◽  
Chromosome Condensation ◽  
Late Prophase ◽  
Homologous Chromosomes ◽  
Prophase I ◽  
Meiotic Prophase I ◽  
Evolutionarily Conserved ◽  
Key Events

During meiosis, evolutionarily conserved mechanisms regulate chromosome remodeling, leading to the formation of a tight bivalent structure. This bivalent, a linked pair of homologous chromosomes, is essential for proper chromosome segregation in meiosis. The formation of a tight bivalent involves chromosome condensation and restructuring around the crossover. The synaptonemal complex (SC), which mediates homologous chromosome association before crossover formation, disassembles concurrently with increased condensation during bivalent remodeling. Both chromosome condensation and SC disassembly are likely critical steps in acquiring functional bivalent structure. The mechanisms controlling SC disassembly, however, remain unclear. Here we identify akir-1 as a gene involved in key events of meiotic prophase I in Caenorhabditis elegans. AKIR-1 is a protein conserved among metazoans that lacks any previously known function in meiosis. We show that akir-1 mutants exhibit severe meiotic defects in late prophase I, including improper disassembly of the SC and aberrant chromosome condensation, independently of the condensin complexes. These late-prophase defects then lead to aberrant reconfiguring of the bivalent. The meiotic divisions are delayed in akir-1 mutants and are accompanied by lagging chromosomes. Our analysis therefore provides evidence for an important role of proper SC disassembly in configuring a functional bivalent structure.

Three-Dimensional reconstruction of the synaptonemal complex from high-pressure frozen maize meiocytes using IVEM Tomography

1994 ◽  
Vol 52 ◽  
pp. 14-15
Author(s):  
Jennifer C. Fung ◽  
David A. Agard ◽  
John W. Sedat
Keyword(s):  
Synaptonemal Complex ◽  
Three Dimensional ◽  
Central Element ◽  
Homologous Chromosomes ◽  
Macromolecular Assembly ◽  
Dimensional Reconstruction ◽  
Protein Components ◽  
Basic Features ◽  
General Architecture ◽  
Internal Architecture

The synaptonemal complex (SC) is a key macromolecular assembly formed during meiosis of most eukaryotes. It has a crucial role in maintaining synapsis between homologous chromosomes and in ensuring proper segregation of the homologs through the establishment of functional chiasmata. Recently, biochemical and genetic efforts have begun to identify some of the protein components of the SC. As these efforts progress, a more detailed analysis of SC structure will also be needed to incorporate these new components into the overall organization of the SC.Early efforts into the analysis of SC structure have established that its general architecture is conserved throughout many organisms. The basic features found in every SC are the two lateral elements and the central element, both which run longitudinally between the homologs during the pachytene stage of prophase I. Transverse elements which run perpendicular to the homolog axis through the central region are also often found. Although the general features of the SC are conserved, the internal architecture of these components can differ.

Three-Dimensional reconstruction of the synaptonemal complex from pachytene maize meiocytes using Electron Microscopy tomography

1993 ◽  
Vol 51 ◽  
pp. 182-183
Author(s):  
Jennifer C. Fung ◽  
Bethe A. Scalettar ◽  
David A. Agard ◽  
John W. Sedat
Keyword(s):  
Electron Microscopy ◽  
Synaptonemal Complex ◽  
Chromosome Segregation ◽  
Three Dimensional ◽  
Central Element ◽  
Amorphous Structure ◽  
Two Dimensional ◽  
Homologous Chromosomes ◽  
Exact Function ◽  
Dimensional Reconstruction

The synaptonemal complex (SC) is a structure involved in the synapsis of homologous chromosomes during the prophase I stage of meiosis. Although the exact function of the complex is unknown, it has been suggested that one possible role might be to promote recombination by ensuring close synapsis of the homologous chromosomes. In addition, it is thought that the SC may also be required to convert the resulting recombination events into functional chiasmata to provide for proper chromosome segregation at the end of the first stage of meiosis.The SC structure itself is highly conserved across a variety of species. The organization of the SC is tripartite consisting of lateral, central and transverse elements. Two-dimensional cytological observations have been made to characterize the general features of these SC components. The lateral elements are 300 - 500 Å wide proteinaceous structures which flank the synapsed regions of the chromosome bivalent. Between the two lateral elements is a central region containing the central element commonly characterized as a less dense amorphous structure.

scholarly journals SUMO Localizes to the Central Element of Synaptonemal Complex and Is Required for the Full Synapsis of Meiotic Chromosomes in Budding Yeast

PLoS Genetics ◽  
2013 ◽  
Vol 9 (10) ◽  
pp. e1003837 ◽  
Author(s):  
Karen Voelkel-Meiman ◽  
Louis F. Taylor ◽  
Pritam Mukherjee ◽  
Neil Humphryes ◽  
Hideo Tsubouchi ◽  
...  
Keyword(s):  
Synaptonemal Complex ◽  
Budding Yeast ◽  
Central Element ◽  
Meiotic Chromosomes

scholarly journals The synaptonemal complex has liquid crystalline properties and spatially regulates meiotic recombination factors

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Ofer Rog ◽  
Simone Köhler ◽  
Abby F Dernburg
Keyword(s):  
Signal Transduction ◽  
Synaptonemal Complex ◽  
Meiotic Recombination ◽  
Liquid Crystalline ◽  
Hydrophobic Interactions ◽  
Rapid Evolution ◽  
Three Dimensional ◽  
Homologous Chromosomes ◽  
Meiotic Progression ◽  
Meiotic Chromosomes

The synaptonemal complex (SC) is a polymer that spans ~100 nm between paired homologous chromosomes during meiosis. Its striated, periodic appearance in electron micrographs led to the idea that transverse filaments within this structure ‘crosslink’ the axes of homologous chromosomes, stabilizing their pairing. SC proteins can also form polycomplexes, three-dimensional lattices that recapitulate the periodic structure of SCs but do not associate with chromosomes. Here we provide evidence that SCs and polycomplexes contain mobile subunits and that their assembly is promoted by weak hydrophobic interactions, indicative of a liquid crystalline phase. We further show that in the absence of recombination intermediates, polycomplexes recapitulate the dynamic localization of pro-crossover factors during meiotic progression, revealing how the SC might act as a conduit to regulate chromosome-wide crossover distribution. Properties unique to liquid crystals likely enable long-range signal transduction along meiotic chromosomes and underlie the rapid evolution of SC proteins.

scholarly journals SYCE2 is required for synaptonemal complex assembly, double strand break repair, and homologous recombination

2007 ◽  
Vol 176 (6) ◽  
pp. 741-747 ◽  
Author(s):  
Ewelina Bolcun-Filas ◽  
Yael Costa ◽  
Robert Speed ◽  
Mary Taggart ◽  
Ricardo Benavente ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Synaptonemal Complex ◽  
Protein Interactions ◽  
Central Element ◽  
Strand Break ◽  
Protein Protein Interactions ◽  
Dna Breakage ◽  
Paired Chromosome ◽  
Meiotic Chromosomes ◽  
Males And Females

Synapsis is the process by which paired chromosome homologues closely associate in meiosis before crossover. In the synaptonemal complex (SC), axial elements of each homologue connect through molecules of SYCP1 to the central element, which contains the proteins SYCE1 and -2. We have derived mice lacking SYCE2 protein, producing males and females in which meiotic chromosomes align and axes form but do not synapse. Sex chromosomes are unaligned, not forming a sex body. Additionally, markers of DNA breakage and repair are retained on the axes, and crossover is impaired, culminating in both males and females failing to produce gametes. We show that SC formation can initiate at sites of SYCE1/SYCP1 localization but that these points of initiation cannot be extended in the absence of SYCE2. SC assembly is thus dependent on SYCP1, SYCE1, and SYCE2. We provide a model to explain this based on protein–protein interactions.

scholarly journals Speedy A–Cdk2 binding mediates initial telomere–nuclear envelope attachment during meiotic prophase I independent of Cdk2 activation

2016 ◽  
Vol 114 (3) ◽  
pp. 592-597 ◽  
Author(s):  
Zhaowei Tu ◽  
Mustafa Bilal Bayazit ◽  
Hongbin Liu ◽  
Jingjing Zhang ◽  
Kiran Busayavalasa ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Germ Cells ◽  
Meiotic Prophase ◽  
Homologous Pairing ◽  
Male And Female ◽  
Homologous Chromosomes ◽  
Cyclin Dependent Kinases ◽  
Prophase I ◽  
Meiotic Prophase I ◽  
Localization Domain

Telomere attachment to the nuclear envelope (NE) is a prerequisite for chromosome movement during meiotic prophase I that is required for pairing of homologous chromosomes, synapsis, and homologous recombination. Here we show that Speedy A, a noncanonical activator of cyclin-dependent kinases (Cdks), is specifically localized to telomeres in prophase I male and female germ cells in mice, and plays an essential role in the telomere–NE attachment. Deletion of Spdya in mice disrupts telomere–NE attachment, and this impairs homologous pairing and synapsis and leads to zygotene arrest in male and female germ cells. In addition, we have identified a telomere localization domain on Speedy A covering the distal N terminus and the Cdk2-binding Ringo domain, and this domain is essential for the localization of Speedy A to telomeres. Furthermore, we found that the binding of Cdk2 to Speedy A is indispensable for Cdk2’s localization on telomeres, suggesting that Speedy A and Cdk2 might be the initial components that are recruited to the NE for forming the meiotic telomere complex. However, Speedy A-Cdk2–mediated telomere–NE attachment is independent of Cdk2 activation. Our results thus indicate that Speedy A and Cdk2 might mediate the initial telomere–NE attachment for the efficient assembly of the telomere complex that is essential for meiotic prophase I progression.

scholarly journals A close-to-native structure of the synaptonemal complex

2021 ◽  
Author(s):  
Rosario Ortiz ◽  
Olga M Echeverria ◽  
Sergej Masich ◽  
Christer Hoog ◽  
Abrahan Hernandez-Hernandez
Keyword(s):  
Electron Microscopy ◽  
Genetic Variability ◽  
Synaptonemal Complex ◽  
Central Region ◽  
Genetic Material ◽  
Central Element ◽  
Structural Models ◽  
Super Resolution ◽  
Native Structure ◽  
Homologous Chromosomes

Genetic variability in sexually reproducing organisms results from an exchange of genetic material between homologous chromosomes. The genetic exchange mechanism is dependent on the synaptonemal complex (SC), a protein structure localized between the homologous chromosomes. Current structural models of the SC are based on electron microscopy, super resolution, and expansion microscopy studies using chemical fixatives and sample dehydration of gonads, which are methodologies known to produce structural artifacts. We have developed a novel electron microscopy sample-preparation approach where pachytene cells are isolated from mouse testis by FACS, followed by cryo-fixation and cryo-substitution to achieve visualization of a close-to-native structure of the SC. We found that the central region of the SC was wider than previously recognized, and the transverse filaments more densely packed in the central region. Furthermore, we identified a structure nucleating the central element of the SC.

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