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Meiotic recombination

Shintaro Yamada, Kazuto Kugou, Da-Qiao Ding, Yurika Fujita, Yasushi Hiraoka, Hiroshi Murakami, Kunihiro Ohta, Takatomi Yamada
Meiotic recombination is initiated by programmed formation of DNA double strand breaks (DSBs), which are mainly formed at recombination hotspots. Meiotic DSBs require multiple proteins including the conserved protein Spo11 and its cofactors, and are influenced by chromatin structure. For example, local chromatin around hotspots directly impacts DSB formation. Moreover, DSB is proposed to occur in a higher-order chromatin architecture termed 'axis-loop', in which many loops protrude from cohesin-enriched axis...
November 14, 2017: Nucleic Acids Research
Reka K Kelemen, Beatriz Vicoso
The t-haplotype, a mouse meiotic driver found on chromosome 17, has been a model for autosomal segregation distortion for close to a century, but several questions remain regarding its biology and evolutionary history. A recently published set of population genomics resources for wild mice includes several individuals heterozygous for the t-haplotype, which we use to characterize this selfish element at the genomic and transcriptomic level. Our results show that large sections of the t-haplotype have been replaced by standard homologous sequences, possibly due to occasional events of recombination, and that this complicates the inference of its history...
November 14, 2017: Genetics
Robert A Sclafani, Jay R Hesselberth
Although Cdc7 protein kinase is important for regulating DNA replication in all eukaryotes and is a target for cancer therapy, it has never been localized in cells. Recently, a novel molecular genomic method used by our laboratory to localize Cdc7 to regions of chromosomes. Originally, mutations in the CDC7 gene were found in the classic cdc mutant collection of Hartwell et al. (Genetics 74:267-286, 1973). The CDC7 gene was found to encode a protein kinase called DDK that has been studied for many years, establishing its precise role in the initiation of DNA replication at origins...
November 13, 2017: Current Genetics
Vera Moiseeva, Hanna Amelina, Laura C Collopy, Christine A Armstrong, Siân R Pearson, Kazunori Tomita
During meiotic prophase, chromosome arrangement and oscillation promote the pairing of homologous chromosomes for meiotic recombination. This dramatic movement involves clustering of telomeres at the nuclear membrane to form the so-called telomere bouquet. In fission yeast, the telomere bouquet is formed near the spindle pole body (SPB), which is the microtubule organising centre, functionally equivalent to the metazoan centrosome. Disruption of bouquet configuration impedes homologous chromosome pairing, meiotic recombination and spindle formation...
2017: Cell Discovery
Guanqing Jia, Haigang Wang, Sha Tang, Hui Zhi, Sichen Liu, Qifen Wen, Zhijun Qiao, Xianmin Diao
Meiotic recombination is essential to sexual reproduction and the generation of genetic diversity. Variation in recombination rates is presently of particular interest due to efforts being made to increase the rate of genetic gain in agricultural crops by breaking up large linkage disequilibrium blocks containing both beneficial and detrimental alleles. Here, a high-density genetic linkage map of Setaria was constructed using tunable genotyping by sequencing (tGBS) analysis of a population of recombinant inbred lines (RILs)...
November 9, 2017: Scientific Reports
Elias ElInati, Helen R Russell, Obah A Ojarikre, Mahesh Sangrithi, Takayuki Hirota, Dirk G de Rooij, Peter J McKinnon, James M A Turner
Meiotic synapsis and recombination between homologs permits the formation of cross-overs that are essential for generating chromosomally balanced sperm and eggs. In mammals, surveillance mechanisms eliminate meiotic cells with defective synapsis, thereby minimizing transmission of aneuploidy. One such surveillance mechanism is meiotic silencing, the inactivation of genes located on asynapsed chromosomes, via ATR-dependent serine-139 phosphorylation of histone H2AFX (γH2AFX). Stimulation of ATR activity requires direct interaction with an ATR activation domain (AAD)-containing partner...
November 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
Harris Bernstein, Carol Bernstein, Richard E Michod
We review the sexual processes common in pathogenic microorganisms and assess the primary adaptive benefit of such processes. The pathogenic microorganisms considered include bacteria, microbial eukaryotes, and viruses. The sexual processes include bacterial transformation, eukaryotic meiotic sex and virus multiplicity reactivation. Recent evidence shows that sexual processes are common in microbial pathogens. A major general challenge to pathogen survival and infectivity is the need to overcome the hostile defenses of their target host...
October 27, 2017: Infection, Genetics and Evolution
Christopher H Morgan, Huakun Zhang, Kirsten Bomblies
Meiosis is unusual among cell divisions in shuffling genetic material by crossovers among homologous chromosomes and partitioning the genome into haploid gametes. Crossovers are critical for chromosome segregation in most eukaryotes, but are also an important factor in evolution, as they generate novel genetic combinations. The molecular mechanisms that underpin meiotic recombination and chromosome segregation are well conserved across kingdoms, but are also sensitive to perturbation by environment, especially temperature...
December 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Amy L Dapper, Bret A Payseur
Meiotic recombination is necessary for successful gametogenesis in most sexually reproducing organisms and is a fundamental genomic parameter, influencing the efficacy of selection and the fate of new mutations. The molecular and evolutionary functions of recombination should impose strong selective constraints on the range of recombination rates. Yet, variation in recombination rate is observed on a variety of genomic and evolutionary scales. In the past decade, empirical studies have described variation in recombination rate within genomes, between individuals, between sexes, between populations and between species...
December 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Isabel Alves, Armande Ang Houle, Julie G Hussin, Philip Awadalla
Recombination promotes genomic integrity among cells and tissues through double-strand break repair, and is critical for gamete formation and fertility through a strict regulation of the molecular mechanisms associated with proper chromosomal disjunction. In humans, congenital defects and recurrent structural abnormalities can be attributed to aberrant meiotic recombination. Moreover, mutations affecting genes involved in recombination pathways are directly linked to pathologies including infertility and cancer...
December 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Laurie S Stevison, Stephen Sefick, Chase Rushton, Rita M Graze
For over a century, scientists have known that meiotic recombination rates can vary considerably among individuals, and that environmental conditions can modify recombination rates relative to the background. A variety of external and intrinsic factors such as temperature, age, sex and starvation can elicit 'plastic' responses in recombination rate. The influence of recombination rate plasticity on genetic diversity of the next generation has interesting and important implications for how populations evolve...
December 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Tyler V Kent, Jasmina Uzunović, Stephen I Wright
One of the most striking patterns of genome structure is the tight, typically negative, association between transposable elements (TEs) and meiotic recombination rates. While this is a highly recurring feature of eukaryotic genomes, the mechanisms driving correlations between TEs and recombination remain poorly understood, and distinguishing cause versus effect is challenging. Here, we review the evidence for a relation between TEs and recombination, and discuss the underlying evolutionary forces. Evidence to date suggests that overall TE densities correlate negatively with recombination, but the strength of this correlation varies across element types, and the pattern can be reversed...
December 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Juanjuan Long, Chenhui Huang, Yanyan Chen, Ying Zhang, Shaohua Shi, Ligang Wu, Yie Liu, Chengyu Liu, Jian Wu, Ming Lei
During meiotic prophase, the meiosis-specific telomere-binding protein TERB1 regulates chromosome movement required for homologous pairing and recombination by interacting with the telomeric shelterin subunit TRF1. Here, we report the crystal structure of the TRF1-binding motif of human TERB1 in complex with the TRFH domain of TRF1. Notably, specific disruption of the TERB1-TRF1 interaction by a point mutation in the mouse Terb1 gene results in infertility only in males. We find that this mutation causes an arrest in the zygotene-early pachytene stage and mild telomere abnormalities of autosomes but unpaired X and Y chromosomes in pachytene, leading to massive spermatocyte apoptosis...
October 30, 2017: Nature Structural & Molecular Biology
Kim Osman, Jianhua Yang, Elisabeth Roitinger, Christophe Lambing, Stefan Heckmann, Elaine Howell, Maria Cuacos, Richard Imre, Gerhard Dürnberger, Karl Mechtler, Sue Armstrong, F Chris H Franklin
During meiosis, formation of crossovers (COs) generates genetic variation and provides physical links essential for accurate chromosome segregation. COs occur in the context of a proteinaceous chromosome axis. The transcriptomes and proteomes of anthers and meiocytes comprise several thousand genes and proteins but due to the level of complexity relatively few have been functionally characterised. Understanding of the physical and functional interactions between meiotic proteins is also limited. Here we use affinity proteomics to analyse the proteins that are associated with the meiotic chromosome axis protein, ASY1, in Brassica oleracea anthers and meiocytes...
October 27, 2017: Plant Journal: for Cell and Molecular Biology
Nicolas Altemose, Nudrat Noor, Emmanuelle Bitoun, Afidalina Tumian, Michael Imbeault, J Ross Chapman, A Radu Aricescu, Simon R Myers
PRDM9 binding localizes almost all meiotic recombination sites in humans and mice. However, most PRDM9-bound loci do not become recombination hotspots. To explore factors that affect binding and subsequent recombination outcomes, we mapped human PRDM9 binding sites in a transfected human cell line and measured PRDM9-induced histone modifications. These data reveal varied DNA-binding modalities of PRDM9. We also find that human PRDM9 frequently binds promoters, despite their low recombination rates, and it can activate expression of a small number of genes including CTCFL and VCX...
October 26, 2017: ELife
Steven J Foulis, Kyle R Fowler, Walter W Steiner
Homologous recombination occurs at a greatly elevated frequency in meiosis compared to mitosis and is initiated by programmed double-strand DNA breaks (DSBs). DSBs do not occur at uniform frequency throughout the genome in most organisms, but occur preferentially at a limited number of sites referred to as hotspots. The location of hotspots have been determined at nucleotide-level resolution in both the budding and fission yeasts, and while several patterns have emerged regarding preferred locations for DSB hotspots, it remains unclear why particular sites experience DSBs at much higher frequency than other sites with seemingly similar properties...
October 25, 2017: Genetica
Hideo Tsubouchi, Bilge Argunhan, Tomomi Tsubouchi
The meiotic cell cycle provides a unique model to study the relationship between recombinational DNA repair and the cell cycle, since homologous recombination, induced by programmed DNA double-strand breaks (DSBs), is integrated as an essential step during meiosis. The pachytene checkpoint, which is situated towards the end of meiotic prophase I, coordinates homologous recombination and cell cycle progression, similar to the DNA damage checkpoint mechanisms operating in vegetative cells. However, there are a number of features unique to meiosis, making the system optimized for the purpose of meiosis...
October 25, 2017: Current Genetics
(no author information available yet)
[This corrects the article DOI: 10.1371/journal.pgen.1006974.].
October 2017: PLoS Genetics
Yixin Wang, Long Jin, Jideng Ma, Li Chen, Yuhua Fu, Keren Long, Silu Hu, Yang Song, Dazhi Shang, Qianzi Tang, Xun Wang, Xuewei Li, Mingzhou Li
Purpose: Hemicastration is a unilateral orchiectomy to remove an injured testis, which can induce hormonal changes and compensatory hypertrophy of the remaining testis, and may influence spermatogenesis. However, the underlying molecular mechanisms are poorly understood. Here, we investigated the impact of hemicastration on remaining testicular function. Methods: Prepubertal mice (age 24 days) were hemicastrated, and their growth was monitored until they reached physical maturity (age 72 days)...
October 20, 2017: Asian-Australasian Journal of Animal Sciences
Nadezhda M Belonogova, Andrei V Polyakov, Tatyana V Karamysheva, Anna A Torgasheva, Jeremy B Searle, Pavel M Borodin
Hybrid zones between chromosome races of the common shrew (Sorex araneus) provide exceptional models to study the potential role of chromosome rearrangements in the initial steps of speciation. The Novosibirsk and Tomsk races differ by a series of Robertsonian fusions with monobrachial homology. They form a narrow hybrid zone and generate hybrids with both simple (chain of three chromosomes) and complex (chain of eight or nine) synaptic configurations. Using immunolocalisation of the meiotic proteins, we examined chromosome pairing and recombination in males from the hybrid zone...
October 20, 2017: Genes
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