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Meiotic recombination

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https://www.readbyqxmd.com/read/28101670/recombination-correlates-with-synaptonemal-complex-length-and-chromatin-loop-size-in-bovids-insights-into-mammalian-meiotic-chromosomal-organization
#1
Aurora Ruiz-Herrera, Miluse Vozdova, Jonathan Fernández, Hana Sebestova, Laia Capilla, Jan Frohlich, Covadonga Vara, Adrià Hernández-Marsal, Jaroslav Sipek, Terence J Robinson, Jiri Rubes
Homologous chromosomes exchange genetic information through recombination during meiosis, a process that increases genetic diversity, and is fundamental to sexual reproduction. In an attempt to shed light on the dynamics of mammalian recombination and its implications for genome organization, we have studied the recombination characteristics of 112 individuals belonging to 28 different species in the family Bovidae. In particular, we analyzed the distribution of RAD51 and MLH1 foci during the meiotic prophase I that serve, respectively, as proxies for double-strand breaks (DSBs) which form in early stages of meiosis and for crossovers...
January 18, 2017: Chromosoma
https://www.readbyqxmd.com/read/28100637/a-zip3-like-protein-plays-a-role-in-crossover-formation-in-the-sc-less-meiosis-of-the-protist-tetrahymena
#2
Anura Shodhan, Kensuke Kataoka, Kazufumi Mochizuki, Maria Novatchkova, Josef Loidl
When programmed meiotic DNA double-strand breaks (DSBs) undergo recombinational repair, genetic crossovers (COs) may be formed. A certain level of these are required for the faithful segregation of chromosomes, but the majority of DSBs are processed toward a safer alternative, namely non-crossovers (NCOs), via non-reciprocal DNA exchange. At the crossroads between these two DSB fates are the Msh4-Msh5 (MutSγ) complex, which stabilizes CO-destined recombination intermediates, and members of the Zip3/RNF212 family of RING finger proteins, which in turn stabilize MutSγ...
January 18, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28100589/meiotic-consequences-of-genetic-divergence-across-the-murine-pseudoautosomal-region
#3
Beth L Dumont
The production of haploid gametes during meiosis is dependent on the homology-driven processes of pairing, synapsis, and recombination. On the mammalian heterogametic sex chromosomes, these key meiotic activities are confined to the pseudoautosomal region (PAR), a short region of near-perfect sequence homology between the X and Y chromosomes. Despite its established importance for meiosis, the PAR is rapidly evolving, raising the question of how proper X/Y segregation is buffered against the accumulation of homology-disrupting mutations...
January 18, 2017: Genetics
https://www.readbyqxmd.com/read/28073018/meiotic-recombination-taking-the-path-less-traveled
#4
Danny E Miller, R Scott Hawley
The proper distribution of crossovers during meiosis I ensures accurate chromosome segregation at the first meiotic division. A new study reveals both the consequences of improper crossover patterning in Drosophila and the role of Blm helicase in controlling this patterning.
January 9, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28069706/dna-sequence-properties-that-predict-susceptibility-to-epiallelic-switching
#5
Marco Catoni, Jayne Griffiths, Claude Becker, Nicolae Radu Zabet, Carlos Bayon, Mélanie Dapp, Michal Lieberman-Lazarovich, Detlef Weigel, Jerzy Paszkowski
Transgenerationally heritable epialleles are defined by the stable propagation of alternative transcriptional states through mitotic and meiotic cell cycles. Given that the propagation of DNA methylation at CpG sites, mediated in Arabidopsis by MET1, plays a central role in epigenetic inheritance, we examined genomewide DNA methylation in partial and complete loss-of-function met1 mutants. We interpreted the data in relation to transgenerational epiallelic stability, which allowed us to classify chromosomal targets of epigenetic regulation into (i) single copy and methylated exclusively at CpGs, readily forming epialleles, and (ii) transposon-derived, methylated at all cytosines, which may or may not form epialleles...
January 9, 2017: EMBO Journal
https://www.readbyqxmd.com/read/28059759/a-global-view-of-meiotic-double-strand-break-end-resection
#6
Eleni P Mimitou, Shintaro Yamada, Scott Keeney
DNA double-strand breaks that initiate meiotic recombination are exonucleolytically processed. This 5'→3' resection is a central, conserved feature of recombination but remains poorly understood. To address this lack, we mapped resection endpoints genome-wide at high resolution in Saccharomyces cerevisiae Full-length resection requires Exo1 exonuclease and the DSB-responsive kinase Tel1, but not Sgs1 helicase. Tel1 also promotes efficient and timely resection initiation. Resection endpoints display pronounced heterogeneity between genomic loci that reflects a tendency for nucleosomes to block Exo1, yet Exo1 also appears to digest chromatin with high processivity and at rates similar to naked DNA in vitro...
January 6, 2017: Science
https://www.readbyqxmd.com/read/28059716/a-sumo-ubiquitin-relay-recruits-proteasomes-to-chromosome-axes-to-regulate-meiotic-recombination
#7
H B D Prasada Rao, Huanyu Qiao, Shubhang K Bhatt, Logan R J Bailey, Hung D Tran, Sarah L Bourne, Wendy Qiu, Anusha Deshpande, Ajay N Sharma, Connor J Beebout, Roberto J Pezza, Neil Hunter
Meiosis produces haploid gametes through a succession of chromosomal events including pairing, synapsis and recombination. Mechanisms that orchestrate these events remain poorly understood. We found that the SUMO-modification and ubiquitin-proteasome systems regulate the major events of meiotic prophase in mouse. Interdependent localization of SUMO, ubiquitin and proteasomes along chromosome axes was mediated largely by RNF212 and HEI10, two E3 ligases that are also essential for crossover recombination. RNF212-dependent SUMO conjugation effected a checkpoint-like process that stalls recombination by rendering the turnover of a subset of recombination factors dependent on HEI10-mediated ubiquitylation...
January 5, 2017: Science
https://www.readbyqxmd.com/read/28059715/control-of-meiotic-pairing-and-recombination-by-chromosomally-tethered-26s-proteasome
#8
Jasvinder S Ahuja, Rima Sandhu, Rana Mainpal, Crystal Lawson, Hanna Henley, Patricia A Hunt, Judith L Yanowitz, G Valentin Börner
During meiosis, paired homologous chromosomes (homologs) become linked via the synaptonemal complex (SC) and crossovers. Crossovers mediate homolog segregation and arise from self-inflicted double-strand breaks (DSBs). Here, we identified a role for the proteasome, the multi-subunit protease that degrades proteins in the nucleus and cytoplasm, in homolog juxtaposition and crossing over. Without proteasome function, homologs failed to pair and instead remained associated with non-homologous chromosomes. While dispensable for non-crossover formation, a functional proteasome was required for a coordinated transition that entails SC assembly between longitudinally organized chromosome axes and stable strand exchange of crossover-designated DSBs...
January 5, 2017: Science
https://www.readbyqxmd.com/read/28051769/concerted-action-of-the-mutl%C3%AE-heterodimer-and-mer3-helicase-regulates-the-global-extent-of-meiotic-gene-conversion
#9
Yann Duroc, Rajeev Kumar, Lepakshi Ranjha, Céline Adam, Raphaël Guérois, Khan Md Muntaz, Marie-Claude Marsolier-Kergoat, Florent Dingli, Raphaëlle Laureau, Damarys Loew, Bertrand Llorente, Jean-Baptiste Charbonnier, Petr Cejka, Valérie Borde
Gene conversions resulting from meiotic recombination are critical in shaping genome diversification and evolution. How the extent of gene conversions is regulated is unknown. Here we show that the budding yeast mismatch repair related MutLβ complex, Mlh1-Mlh2, specifically interacts with the conserved meiotic Mer3 helicase, which recruits it to recombination hotspots, independently of mismatch recognition. This recruitment is essential to limit gene conversion tract lengths genome-wide, without affecting crossover formation...
January 4, 2017: ELife
https://www.readbyqxmd.com/read/28045371/the-synaptonemal-complex-has-liquid-crystalline-properties-and-spatially-regulates-meiotic-recombination-factors
#10
Ofer Rog, Simone Köhler, Abby F Dernburg
The synaptonemal complex (SC) is a polymer that spans ~100nm 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...
January 3, 2017: ELife
https://www.readbyqxmd.com/read/28031483/speedy-a-cdk2-binding-mediates-initial-telomere-nuclear-envelope-attachment-during-meiotic-prophase-i-independent-of-cdk2-activation
#11
Zhaowei Tu, Mustafa Bilal Bayazit, Hongbin Liu, Jingjing Zhang, Kiran Busayavalasa, Sanjiv Risal, Jingchen Shao, Ande Satyanarayana, Vincenzo Coppola, Lino Tessarollo, Meenakshi Singh, Chunwei Zheng, Chunsheng Han, Zijiang Chen, Philipp Kaldis, Jan-Åke Gustafsson, Kui Liu
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...
January 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28030854/the-chromosomes-of-birds-during-meiosis
#12
María I Pigozzi
The cytological analysis of meiotic chromosomes is an exceptional tool to approach complex processes such as synapsis and recombination during the division. Chromosome studies of meiosis have been especially valuable in birds, where naturally occurring mutants or experimental knock-out animals are not available to fully investigate the basic mechanisms of major meiotic events. This review highlights the main contributions of synaptonemal complex and lampbrush chromosome research to the current knowledge of avian meiosis, with special emphasis on the organization of chromosomes during prophase I, the impact of chromosome rearrangements during meiosis, and distinctive features of the ZW pair...
December 29, 2016: Cytogenetic and Genome Research
https://www.readbyqxmd.com/read/28007967/aberrant-meiotic-modulation-partially-contributes-to-the-lower-germination-rate-of-pollen-grains-in-maize-zea-mays-l-under-low-nitrogen-supply
#13
Hongyan Zheng, Huamao Wu, Xiaoying Pan, Weiwei Jin, Xuexian Li
Pollen germination is an essential step towards successful pollination during maize reproduction. How low niutrogen (N) affects pollen germination remains an interesting biological question to be addressed. We found that only low N resulted in a significantly lower germination rate of pollen grains after 4 weeks of low N, phosphorus or potassium treatment in maize production. Importantly, cytological analysis showed 7-fold more micronuclei in male meiocytes under the low N treatment than in the control, indicating that the lower germination rate of pollen grains was partially due to numerous chromosome loss events resulting from preceding meiosis...
November 15, 2016: Plant & Cell Physiology
https://www.readbyqxmd.com/read/28005992/do-exogenous-dna-double-strand-breaks-change-incomplete-synapsis-and-chiasma-localization-in-the-grasshopper-stethophyma-grossum
#14
Adela Calvente, Juan Luis Santos, Julio S Rufas
Meiotic recombination occurs as a programmed event that initiates by the formation of DNA double-strand breaks (DSBs) that give rise to the formation of crossovers that are observed as chiasmata. Chiasmata are essential for the accurate chromosome segregation and the generation of new combinations of parental alleles. Some treatments that provoke exogenous DSBs also lead to alterations in the recombination pattern of some species in which full homologous synapsis is achieved at pachytene. We have carried out a similar approach in males of the grasshopper Stethophyma grossum, whose homologues show incomplete synapsis and proximal chiasma localization...
2016: PloS One
https://www.readbyqxmd.com/read/27989672/bloom-syndrome-helicase-promotes-meiotic-crossover-patterning-and-homolog-disjunction
#15
Talia Hatkevich, Kathryn P Kohl, Susan McMahan, Michaelyn A Hartmann, Andrew M Williams, Jeff Sekelsky
In most sexually reproducing organisms, crossover formation between homologous chromosomes is necessary for proper chromosome disjunction during meiosis I. During meiotic recombination, a subset of programmed DNA double-strand breaks (DSBs) are repaired as crossovers, with the remainder becoming noncrossovers [1]. Whether a repair intermediate is designated to become a crossover is a highly regulated decision that integrates several crossover patterning processes, both along chromosome arms (interference and the centromere effect) and between chromosomes (crossover assurance) [2]...
January 9, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/27986806/repair-of-meiotic-dna-breaks-and-homolog-pairing-in-mouse-meiosis-requires-a-minichromosome-maintenance-mcm-paralog
#16
Adrian J McNairn, Vera D Rinaldi, John C Schimenti
The mammalian Mcm-domain containing 2 (Mcmdc2) gene encodes a protein of unknown function that is homologous to the mini-chromosome maintenance family of DNA replication licensing and helicase factors. Drosophila melanogaster contains two separate genes, the "Mei-MCMs," that appear to have arisen from a single ancestral Mcmdc2 gene. The Mei-MCMs are involved in promoting meiotic crossovers by blocking the anti-crossover activity of BLM helicase, a function presumably performed by MSH4 and MSH5 in metazoans...
December 16, 2016: Genetics
https://www.readbyqxmd.com/read/27974736/hed1-promotes-meiotic-crossover-formation-in-saccharomyces-cerevisiae
#17
Yoon-Ju Kong, Jeong-Hwan Joo, Keun Pil Kim, Soogil Hong
Homologous recombination (HR) occurs between homologous chromosomes and is significantly involved in programmed double-strand breaks (DSB) repair. Activation of two recombinases, Rad51 and Dmc1, is essential for an inter-homolog bias during meiosis. Rad51 participates in both mitotic and meiotic recombination, and its strand exchange activity is regulated by an inhibitory factor during meiosis. Thus, activities of Rad51 and Dmc1 are coordinated to promote homolog bias. It has been reported that Hed1, a meiosis-specific protein in budding yeast, regulates Rad51-dependent recombination activity...
December 14, 2016: Journal of Microbiology and Biotechnology
https://www.readbyqxmd.com/read/27974520/recombination-in-the-eggs-and-sperm-in-a-simultaneously-hermaphroditic-vertebrate
#18
L Theodosiou, W O McMillan, O Puebla
When there is no recombination (achiasmy) in one sex, it is in the heterogametic one. This observation is so consistent that it constitutes one of the few patterns in biology that may be regarded as a 'rule' and Haldane (Haldane 1922 J. Genet. 12, 101-109. (doi:10.1007/BF02983075)) proposed that it might be driven by selection against recombination in the sex chromosomes. Yet differences in recombination rates between the sexes (heterochiasmy) have also been reported in hermaphroditic species that lack sex chromosomes...
December 14, 2016: Proceedings. Biological Sciences
https://www.readbyqxmd.com/read/27965412/rmi1-and-top3%C3%AE-limit-meiotic-co-formation-through-their-c-terminal-domains
#19
Mathilde Séguéla-Arnaud, Sandrine Choinard, Cécile Larchevêque, Chloé Girard, Nicole Froger, Wayne Crismani, Raphael Mercier
At meiosis, hundreds of programmed DNA double-strand breaks (DSBs) form and are repaired by homologous recombination. From this large number of DSBs, only a subset yields crossovers (COs), with a minimum of one CO per chromosome pair. All DSBs must be repaired and every recombination intermediate must be resolved to avoid subsequent entanglement and chromosome breakage. The conserved BLM-TOP3α-RMI1 (BTR) complex acts on early and late meiotic recombination intermediates to both limit CO outcome and promote chromosome integrity...
December 13, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27956467/linc-complexes-promote-homologous-recombination-in-part-through-inhibition-of-nonhomologous-end-joining
#20
Katherine S Lawrence, Erin C Tapley, Victor E Cruz, Qianyan Li, Kayla Aung, Kevin C Hart, Thomas U Schwartz, Daniel A Starr, JoAnne Engebrecht
The Caenorhabditis elegans SUN domain protein, UNC-84, functions in nuclear migration and anchorage in the soma. We discovered a novel role for UNC-84 in DNA damage repair and meiotic recombination. Loss of UNC-84 leads to defects in the loading and disassembly of the recombinase RAD-51. Similar to mutations in Fanconi anemia (FA) genes, unc-84 mutants and human cells depleted of Sun-1 are sensitive to DNA cross-linking agents, and sensitivity is rescued by the inactivation of nonhomologous end joining (NHEJ)...
December 19, 2016: Journal of Cell Biology
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