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Meiotic recombination

Kristoffer Krogerus, Tuulikki Seppänen-Laakso, Sandra Castillo, Brian Gibson
BACKGROUND: Interspecific hybridization has proven to be a potentially valuable technique for generating de novo lager yeast strains that possess diverse and improved traits compared to their parent strains. To further enhance the value of hybridization for strain development, it would be desirable to combine phenotypic traits from more than two parent strains, as well as remove unwanted traits from hybrids. One such trait, that has limited the industrial use of de novo lager yeast hybrids, is their inherent tendency to produce phenolic off-flavours; an undesirable trait inherited from the Saccharomyces eubayanus parent...
April 21, 2017: Microbial Cell Factories
Bilge Argunhan, Yasuto Murayama, Hiroshi Iwasaki
Homologous recombination (HR) is the process whereby two DNA molecules that share high sequence similarity are able to recombine to generate hybrid DNA molecules. Throughout evolution, the ability of HR to identify highly similar DNA sequences has been adopted for numerous biological phenomena including DNA repair, meiosis, telomere maintenance, ribosomal DNA amplification, and immunological diversity. Although Rad51 and Dmc1 are the key proteins that promote HR in mitotic and meiotic cells, respectively, accessory proteins that allow Rad51 and Dmc1 to effectively fulfil their functions have been identified in all examined model systems...
April 19, 2017: FEBS Letters
Yufei Xu, Jian Wang
Primary ovarian insuffiency (POI), which accounts for female infertility, is characterized by amenorrhea before the age of 40 and high serum level of follicular stimulating hormone (>40 U/L) at two measurements taken at least one month apart. The disorder is believed to have a strong genetic component. A large number of candidate genes have been proposed, though few of them were extensively studied. With the rapid evolvement of genome sequencing technology, recent research raised the possibility that the genes involved in essential steps of meiosis such as chromosome synapsis and recombination play an important role in the pathogenesis of POI...
April 10, 2017: Zhonghua Yi Xue Yi Chuan Xue za Zhi, Zhonghua Yixue Yichuanxue Zazhi, Chinese Journal of Medical Genetics
Shintaro Yamada, Mika Okamura, Arisa Oda, Hiroshi Murakami, Kunihiro Ohta, Takatomi Yamada
Meiotic homologous recombination, a critical event for ensuring faithful chromosome segregation and creating genetic diversity, is initiated by programed DNA double strand breaks (DSBs) formed at recombination hotspots. Meiotic DSB formation is likely to be influenced by other DNA-templated processes including transcription, but how DSB formation and transcription interact with each other has not been understood well. In this study, we used fission yeast to investigate a possible interplay of these two events...
April 10, 2017: Genetics
Ying Zhao, Margaret Dominska, Aleksandra Petrova, Halle Bagshaw, Robert J Kokoska, Thomas D Petes
In the yeast Saccharomyces cerevisiae, the genes encoding the metallothionein protein Cup1 are located in a tandem array on chromosome VIII. Using a diploid strain that is heterozygous for an insertion of a selectable marker (URA3) within this tandem array, and heterozygous for markers flanking the array, we measured inter-homolog recombination and intra-/sister-chromatid exchange in the CUP1 locus. The rate of intra-/sister chromatid recombination exceeded the rate of inter-homolog recombination by more than ten-fold...
April 4, 2017: Genetics
Y Q Shirleen Soh, Maria M Mikedis, Mina Kojima, Alexander K Godfrey, Dirk G de Rooij, David C Page
The meiosis-specific chromosomal events of homolog pairing, synapsis, and recombination occur over an extended meiotic prophase I that is many times longer than prophase of mitosis. Here we show that, in mice, maintenance of an extended meiotic prophase I requires the gene Meioc, a germ-cell specific factor conserved in most metazoans. In mice, Meioc is expressed in male and female germ cells upon initiation of and throughout meiotic prophase I. Mouse germ cells lacking Meioc initiate meiosis: they undergo pre-meiotic DNA replication, they express proteins involved in synapsis and recombination, and a subset of cells progress as far as the zygotene stage of prophase I...
April 2017: PLoS Genetics
O Mihola, Z Trachtulec
PRDM9 is a protein with histone-3-methyltransferase activity, which specifies the sites of meiotic recombination in mammals. Deficiency of the Prdm9 gene in the laboratory mouse results in complete arrest of the meiotic prophase of both sexes. Moreover, the combination of certain PRDM9 alleles from different mouse subspecies causes hybrid sterility, e.g., the male-specific meiotic arrest found in the (PWD/Ph × C57BL/6J)F1 animals. The fertility of all these mice can be rescued using a Prdm9-containing transgene...
2017: Folia Biologica (Praha)
Lian Zhou, Jingluan Han, Yuanling Chen, Yingxiang Wang, Yao-Guang Liu
Meiosis is essential for eukaryotic sexual reproduction and plant fertility. In comparison with over 80 meiotic genes identified in Arabidopsis, there are only ~30 meiotic genes characterized in rice (Oryza sativa L.). Many genes involved in the regulation of meiotic progression remain to be determined. In this study, we identified a sterile rice mutant and cloned a new meiotic gene, OsBVF1 (Bivalent Formation 1) by map-based cloning. Molecular genetics and cytological approaches were carried out to address the function of OsBVF1 in meiosis...
March 24, 2017: Journal of Experimental Botany
Roseanne Rosario, Richard W P Smith, Ian R Adams, Richard A Anderson
Study question: Can novel meiotic RNA targets of DAZL (deleted in azoospermia-like) be identified in the human foetal ovary? Summary answer: SYCP1 (synaptonemal complex protein-1), TEX11 (testis expressed 11) and SMC1B (structural maintenance of chromosomes 1B) are novel DAZL targets in the human foetal ovary, thus DAZL may have previously unrecognised roles in the translational regulation of RNAs involved in chromosome cohesion and DNA recombination in the oocyte from the time of initiation of meiosis...
March 1, 2017: Molecular Human Reproduction
Judith Nicholson, Sarah Jevons, Blaz Groselj, Sophie Ellermann, Rebecca Konietzny, Martin Kerr, Benedikt M Kessler, Anne E Kiltie
The MRE11/RAD50/NBS1 (MRN) complex mediates DNA repair pathways, including double-strand breaks induced by radiotherapy. Meiotic recombination 11 homolog (MRE11) is downregulated by histone deacetylase inhibition (HDACi), resulting in reduced levels of DNA repair in bladder cancer cells and radiosensitization. In this study, we show that the mechanism of this downregulation is post-translational and identify a C-terminally truncated MRE11, which is formed after HDAC inhibition as full-length MRE11 is downregulated...
March 31, 2017: Cancer Research
Matthias H Weissensteiner, Andy W C Pang, Ignas Bunikis, Ida Höijer, Olga Vinnere-Petterson, Alexander Suh, Jochen B W Wolf
Accurate and contiguous genome assembly is key to a comprehensive understanding of the processes shaping genomic diversity and evolution. Yet, it is frequently constrained by constitutive heterochromatin, usually characterized by highly repetitive DNA. As a key feature of genome architecture associated with centromeric and subtelomeric regions, it locally influences meiotic recombination. In this study, we assess the impact of large tandem repeat arrays on the recombination rate landscape in an avian speciation model, the Eurasian crow...
March 30, 2017: Genome Research
Kathryn R Ritz, Mohamed A F Noor, Nadia D Singh
Rates of meiotic recombination are widely variable both within and among species. However, the functional significance of this variation remains largely unknown. Is the observed within-species variation in recombination rate adaptive? Recent work has revealed new insight into the scale and scope of population-level variation in recombination rate. These data indicate that the magnitude of within-population variation in recombination is similar among taxa. The apparent similarity of the variance in recombination rate among individuals between distantly related species suggests that the relative costs and benefits of recombination that establish the upper and lower bounds may be similar across species...
March 27, 2017: Trends in Genetics: TIG
Santiago Cavero, Esther Herruzo, David Ontoso, Pedro A San-Segundo
In meiotic cells, the pachytene checkpoint or meiotic recombination checkpoint is a surveillance mechanism that monitors critical processes, such as recombination and chromosome synapsis, which are essential for proper distribution of chromosomes to the meiotic progeny. Failures in these processes lead to the formation of aneuploid gametes. Meiotic recombination occurs in the context of chromatin; in fact, the histone methyltransferase Dot1 and the histone deacetylase Sir2 are known regulators of the pachytene checkpoint in Saccharomyces cerevisiae...
December 4, 2016: Microbial Cell
Martin A White, Shunxin Wang, Liangran Zhang, Nancy Kleckner
Many morphological features, in both physical and biological systems, exhibit spatial patterns that are specifically characterized by a tendency to occur with even spacing (in one, two, or three dimensions). The positions of crossover (CO) recombination events along meiotic chromosomes provide an interesting biological example of such an effect. In general, mechanisms that explain such patterns may (a) be mechanically based, (b) occur by a reaction-diffusion mechanism in which macroscopic mechanical effects are irrelevant, or (c) involve a combination of both types of effects...
2017: Methods in Molecular Biology
Silvia Bonaccorsi, Maurizio Gatti
In Drosophila males, there is no synaptonemal complex and recombination does not occur. Thus, Drosophila male meiosis is a good model system for the analysis of achiasmate chromosome segregation. In addition, due to their large size, the meiotic spindles of Drosophila males are an excellent system for mutational dissection of the mechanisms of spindle assembly. Here, we describe the main techniques for visualization of live Drosophila testes and for preparation of fixed meiotic chromosomes and spindles.
2017: Methods in Molecular Biology
Stacie E Hughes, R Scott Hawley
Drosophila melanogaster has been studied for a century as a genetic model to understand recombination, chromosome segregation, and the basic rules of inheritance. However, it has only been about 25 years since the events that occur during nuclear envelope breakdown, spindle assembly, and chromosome orientation during D. melanogaster female meiosis I were first visualized by fixed cytological methods (Theurkauf and Hawley, J Cell Biol 116:1167-1180, 1992). Although these fixed cytological studies revealed many important details about the events that occur during meiosis I, they failed to elucidate the timing or order of these events...
2017: Methods in Molecular Biology
Harry Scherthan
The mouse (Mus musculus) represents the central mammalian genetic model system for biomedical and developmental research. Mutant mouse models have provided important insights into chromosome dynamics during the complex meiotic differentiation program that compensates for the genome doubling at fertilization. Homologous chromosomes (homologues) undergo dynamic pairing and recombine during first meiotic prophase before they become partitioned into four haploid sets by two consecutive meiotic divisions that lack an intervening S-phase...
2017: Methods in Molecular Biology
Lorinda K Anderson
Immunolocalization using either fluorescence for light microscopy (LM) or gold particles for electron microscopy (EM) has become a common tool to pinpoint proteins involved in recombination during meiotic prophase. Each method has its advantages and disadvantages. For example, LM immunofluorescence is comparatively easier and higher throughput compared to immunogold EM localization. In addition, immunofluorescence has the advantages that a faint signal can often be enhanced by longer exposure times and colocalization using two (or more) probes with different absorbance and emission spectra is straightforward...
2017: Methods in Molecular Biology
Frederick J Bowring, P Jane Yeadon, David E A Catcheside
We have built a series of Neurospora crassa strains containing alleles of green fluorescent protein (GFP) to provide a visual phenotype for investigating meiotic recombination. These strains provide a convenient means of screening the Neurospora knockout library for genes involved in genetic recombination. They permit rapid analysis of recombination outcomes by allowing visualization of segregation patterns in a large number of octads from crosses heterozygous for GFP. Using this system the effect of a knockout on gene conversion and/or on crossing over between the fluorescent marker and the centromere can be measured...
2017: Methods in Molecular Biology
Isabel Lam, Neeman Mohibullah, Scott Keeney
Meiosis is a specialized form of cell division resulting in reproductive cells with a reduced, usually haploid, genome complement. A key step after premeiotic DNA replication is the occurrence of homologous recombination at multiple places throughout the genome, initiated with the formation of DNA double-strand breaks (DSBs) catalyzed by the topoisomerase-like protein Spo11. DSBs are distributed non-randomly in genomes, and understanding the mechanisms that shape this distribution is important for understanding how meiotic recombination influences heredity and genome evolution...
2017: Methods in Molecular Biology
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