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Meiotic recombination

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https://www.readbyqxmd.com/read/28929370/a-termite-symbiotic-mushroom-maximizing-sexual-activity-at-growing-tips-of-vegetative-hyphae
#1
Huei-Mei Hsieh, Mei-Chu Chung, Pao-Yang Chen, Fei-Man Hsu, Wen-Wei Liao, Ai-Ning Sung, Chun-Ru Lin, Chung-Ju Rachel Wang, Yu-Hsin Kao, Mei-Jane Fang, Chi-Yung Lai, Chieh-Chen Huang, Jyh-Ching Chou, Wen-Neng Chou, Bill Chia-Han Chang, Yu-Ming Ju
BACKGROUND: Termitomyces mushrooms are mutualistically associated with fungus-growing termites, which are widely considered to cultivate a monogenotypic Termitomyces symbiont within a colony. Termitomyces cultures isolated directly from termite colonies are heterokaryotic, likely through mating between compatible homokaryons. RESULTS: After pairing homokaryons carrying different haplotypes at marker gene loci MIP and RCB from a Termitomyces fruiting body associated with Odontotermes formosanus, we observed nuclear fusion and division, which greatly resembled meiosis, during each hyphal cell division and conidial formation in the resulting heterokaryons...
September 19, 2017: Botanical Studies (Taipei, Taiwan)
https://www.readbyqxmd.com/read/28924058/localization-of-cdc7-protein-kinase-during-dna-replication-in-saccharomyces-cerevisiae
#2
Daniel Rossbach, D Suzi Bryan, Jay R Hesselberth, Robert Sclafani
DDK, a conserved serine-threonine protein kinase composed of a regulatory subunit, Dbf4, and a catalytic subunit, Cdc7, is essential for DNA replication initiation during S phase of the cell cycle through MCM2-7 helicase phosphorylation. The biological significance of DDK is well characterized, but the full mechanism of how DDK associates with substrates remains unclear. Cdc7 is bound to chromatin in the Saccharomyces cerevisiae genome throughout the cell cycle, but there is little empirical evidence as to specific Cdc7 binding locations...
September 18, 2017: G3: Genes—Genomes—Genetics
https://www.readbyqxmd.com/read/28919954/immunocytological-analysis-of-meiotic-recombination-in-two-anole-lizards-squamata-dactyloidae
#3
Artem P Lisachov, Vladimir A Trifonov, Massimo Giovannotti, Malcolm A Ferguson-Smith, Pavel M Borodin
Although the evolutionary importance of meiotic recombination is not disputed, the significance of interspecies differences in the recombination rates and recombination landscapes remains under-appreciated. Recombination rates and distribution of chiasmata have been examined cytologically in many mammalian species, whereas data on other vertebrates are scarce. Immunolocalization of the protein of the synaptonemal complex (SYCP3), centromere proteins and the mismatch-repair protein MLH1 was used, which is associated with the most common type of recombination nodules, to analyze the pattern of meiotic recombination in the male of two species of iguanian lizards, Anolis carolinensis Voigt, 1832 and Deiroptyx coelestinus (Cope, 1862)...
2017: Comparative Cytogenetics
https://www.readbyqxmd.com/read/28916648/genome-dynamics-of-hybrid-saccharomyces-cerevisiae-during-vegetative-and-meiotic-divisions
#4
Abhishek Dutta, Gen Lin, Ajith V Pankajam, Parijat Chakraborty, Nahush Bhat, Lars M Steinmetz, Koodali T Nishant
Mutation and recombination are the major sources of genetic diversity in all organisms. In the baker's yeast, all mutation rate estimates are in homozygous background. We determined the extent of genetic change through mutation and loss of heterozygosity (LOH) in a heterozygous Saccharomyces cerevisiae genome during successive vegetative and meiotic divisions. We measured genome wide LOH and base mutation rates during vegetative and meiotic divisions in a hybrid (S288c/YJM789) S. cerevisiae strain. The S288c/YJM789 hybrid showed nearly complete reduction in heterozygosity within 31 generations of meioses and improved spore viability...
September 15, 2017: G3: Genes—Genomes—Genetics
https://www.readbyqxmd.com/read/28914051/chromosome-centric-human-proteome-project-allies-with-developmental-biology-a-case-study-of-the-role-of-y-chromosome-genes-in-organ-development
#5
Anna Meyfour, Paria Pooyan, Sara Pahlavan, Mostafa Rezaei-Tavirani, Hamid Gourabi, Hossein Baharvand, Ghasem Hosseini Salekdeh
One of the main goals of Chromosome-Centric Human Proteome Project is to identify protein evidence for missing proteins (MPs). Here, we present a case study of the role of Y chromosome genes in organ development and how to overcome the challenges facing MPs identification by employing human pluripotent stem cell differentiation into cells of different organs yielding unprecedented biological insight into adult silenced proteins. Y chromosome is a male-specific sex chromosome which escapes meiotic recombination...
September 15, 2017: Journal of Proteome Research
https://www.readbyqxmd.com/read/28913952/new-age-ideas-about-age-old-sex-separating-meiosis-from-mating-could-solve-a-century-old-conundrum
#6
Michael Brandeis
Ever since Darwin first addressed it, sexual reproduction reigns as the 'queen' of evolutionary questions. Multiple theories tried to explain how this apparently costly and cumbersome method has become the universal mode of eukaryote reproduction. Most theories stress the adaptive advantages of sex by generating variation, they fail however to explain the ubiquitous persistence of sexual reproduction also where adaptation is not an issue. I argue that the obstacle for comprehending the role of sex stems from the conceptual entanglement of two distinct processes - gamete production by meiosis and gamete fusion by mating (mixis)...
September 14, 2017: Biological Reviews of the Cambridge Philosophical Society
https://www.readbyqxmd.com/read/28870214/plasmodium-vivax-genetic-diversity-and-heterozygosity-in-blood-samples-and-resulting-oocysts-at-the-thai-myanmar-border
#7
Ingfar Soontarawirat, Chiara Andolina, Richard Paul, Nicholas P J Day, Francois Nosten, Charles J Woodrow, Mallika Imwong
BACKGROUND: Polyclonal blood-stage infections of Plasmodium vivax are frequent even in low transmission settings, allowing meiotic recombination between heterologous parasites. Empirical data on meiotic products are however lacking. This study examined microsatellites in oocysts derived by membrane feeding of mosquitoes from blood-stage P. vivax infections at the Thai-Myanmar border. METHODS: Blood samples from patients presenting with vivax malaria were fed to Anopheles cracens by membrane feeding and individual oocysts from midguts were obtained by dissection after 7 days...
September 5, 2017: Malaria Journal
https://www.readbyqxmd.com/read/28855712/mtopvib-interacts-with-atprd1-and-plays-important-roles-in-formation-of-meiotic-dna-double-strand-breaks-in-arabidopsis
#8
Yu Tang, Zhongnan Yin, Yuejuan Zeng, Qinxin Zhang, Liqun Chen, Yan He, Pingli Lu, De Ye, Xueqin Zhang
Meiotic recombination is initiated from the formation of DNA double-strand breaks (DSBs). In Arabidopsis, several proteins, such as AtPRD1, AtPRD2, AtPRD3, AtDFO and topoisomerase (Topo) VI-like complex, have been identified as playing important roles in DSB formation. Topo VI-like complex in Arabidopsis may consist of subunit A (Topo VIA: AtSPO11-1 and AtSPO11-2) and subunit B (Topo VIB: MTOPVIB). Little is known about their roles in Arabidopsis DSB formation. Here, we report on the characterization of the MTOPVIB gene using the Arabidopsis mutant alleles mtopVIB-2 and mtopVIB-3, which were defective in DSB formation...
August 30, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28855376/destabilization-of-the-replication-fork-protection-complex-disrupts-meiotic-chromosome-segregation
#9
Wilber Escorcia, Susan L Forsburg
The replication fork protection complex (FPC) coordinates multiple processes that are crucial for unimpeded passage of the replisome through various barriers and difficult-to-replicate areas of the genome. We examine the function of Swi1 and Swi3, fission yeast's primary FPC components, to elucidate how replication fork stability contributes to DNA integrity in meiosis. We report that destabilization of the FPC results in reduced spore viability, delayed replication, changes in recombination, and chromosome mis-segregation in MI and MII...
August 30, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28851851/multifunctional-involvement-of-a-c2h2-zinc-finger-protein-pbzfp-in-malaria-transmission-histone-modification-and-susceptibility-to-dna-damage-response
#10
Anusha M Gopalakrishnan, Ahmed S I Aly, L Aravind, Nirbhay Kumar
In sexually reproducing organisms, meiosis is an essential step responsible for generation of haploid gametes from diploid somatic cells. The quest for understanding regulatory mechanisms of meiotic recombination in Plasmodium led to identification of a gene encoding a protein that contains 11 copies of C2H2 zinc fingers (ZnF). Reverse genetic approaches were used to create Plasmodium berghei parasites either lacking expression of full-length Plasmodium berghei zinc finger protein (PbZfp) (knockout [KO]) or expressing PbZfp lacking C-terminal zinc finger region (truncated [Trunc])...
August 29, 2017: MBio
https://www.readbyqxmd.com/read/28844861/the-dna-damage-checkpoint-eliminates-mouse-oocytes-with-chromosome-synapsis-failure
#11
Vera D Rinaldi, Ewelina Bolcun-Filas, Hiroshi Kogo, Hiroki Kurahashi, John C Schimenti
Pairing and synapsis of homologous chromosomes during meiosis is crucial for producing genetically normal gametes and is dependent upon repair of SPO11-induced double-strand breaks (DSBs) by homologous recombination. To prevent transmission of genetic defects, diverse organisms have evolved mechanisms to eliminate meiocytes containing unrepaired DSBs or unsynapsed chromosomes. Here we show that the CHK2 (CHEK2)-dependent DNA damage checkpoint culls not only recombination-defective mouse oocytes but also SPO11-deficient oocytes that are severely defective in homolog synapsis...
August 16, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28840245/centromere-dynamics-in-male-and-female-germ-cells
#12
Elaine M Dunleavy, Caitríona M Collins
In sexually reproducing organisms the germ line is the cellular lineage that gives rise to gametes. All germ cells originate from germline stem cells that divide asymmetrically to generate gonial pre-cursors, which are amplified in number by mitotic divisions, undergo meiosis and eventually differentiate into mature gametes (haploid eggs and sperm). Information transmitted with gametes is inherited by offspring, and potentially by subsequent generations, instructing in organismal development and beyond. Meiosis comprises one round of DNA replication, followed by two rounds of chromosome segregation; homologous chromosomes segregate in the first division (meiosis I) and sister chromatids segregate in the second division (meiosis II)...
2017: Progress in Molecular and Subcellular Biology
https://www.readbyqxmd.com/read/28839139/loss-of-function-of-arabidopsis-microrna-machinery-genes-impairs-fertility-and-has-effects-on-homologous-recombination-and-meiotic-chromatin-dynamics
#13
Cecilia Oliver, Mónica Pradillo, Sara Jover-Gil, Nieves Cuñado, María Rosa Ponce, Juan Luis Santos
MicroRNAs (miRNAs) are ~22-nt single-stranded noncoding RNAs with regulatory roles in a wide range of cellular functions by repressing eukaryotic gene expression at a post-transcriptional level. Here, we analyzed the effects on meiosis and fertility of hypomorphic or null alleles of the HYL1, HEN1, DCL1, HST and AGO1 genes, which encode miRNA-machinery components in Arabidopsis. Reduced pollen and megaspore mother cell number and fertility were shown by the mutants analyzed. These mutants also exhibited a relaxed chromatin conformation in male meiocytes at the first meiotic division, and increased chiasma frequency, which is likely to be due to increased levels of mRNAs from key genes involved in homologous recombination...
August 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28827832/mlh3-mutations-in-baker-s-yeast-alter-meiotic-recombination-outcomes-by-increasing-noncrossover-events-genome-wide
#14
Najla Al-Sweel, Vandana Raghavan, Abhishek Dutta, V P Ajith, Luigi Di Vietro, Nabila Khondakar, Carol M Manhart, Jennifer A Surtees, K T Nishant, Eric Alani
Mlh1-Mlh3 is an endonuclease hypothesized to act in meiosis to resolve double Holliday junctions into crossovers. It also plays a minor role in eukaryotic DNA mismatch repair (MMR). To understand how Mlh1-Mlh3 functions in both meiosis and MMR, we analyzed in baker's yeast 60 new mlh3 alleles. Five alleles specifically disrupted MMR, whereas one (mlh3-32) specifically disrupted meiotic crossing over. Mlh1-mlh3 representatives for each class were purified and characterized. Both Mlh1-mlh3-32 (MMR+, crossover-) and Mlh1-mlh3-45 (MMR-, crossover+) displayed wild-type endonuclease activities in vitro...
August 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28826480/recombination-meiotic-expression-and-human-codon-usage
#15
Fanny Pouyet, Dominique Mouchiroud, Laurent Duret, Marie Sémon
Synonymous codon usage (SCU) varies widely among human genes. In particular, genes involved in different functional categories display a distinct codon usage, which was interpreted as evidence that SCU is adaptively constrained to optimize translation efficiency in distinct cellular states. We demonstrate here that SCU is not driven by constraints on tRNA abundance, but by large-scale variation in GC-content, caused by meiotic recombination, via the non-adaptive process of GC-biased gene conversion (gBGC). Expression in meiotic cells is associated with a strong decrease in recombination within genes...
August 15, 2017: ELife
https://www.readbyqxmd.com/read/28820351/genomic-and-chromatin-features-shaping-meiotic-double-strand-break-formation-and-repair-in-mice
#16
Shintaro Yamada, Seoyoung Kim, Sam E Tischfield, Maria Jasin, Julian Lange, Scott Keeney
The SPO11-generated DNA double-strand breaks (DSBs) that initiate meiotic recombination occur non-randomly across genomes, but mechanisms shaping their distribution and repair remain incompletely understood. Here, we expand on recent studies of nucleotide-resolution DSB maps in mouse spermatocytes. We find that trimethylation of histone H3 lysine 36 around DSB hotspots is highly correlated, both spatially and quantitatively, with trimethylation of H3 lysine 4, consistent with coordinated formation and action of both PRDM9-dependent histone modifications...
August 18, 2017: Cell Cycle
https://www.readbyqxmd.com/read/28803330/bime2-a-novel-gene-required-for-interhomolog-meiotic-recombination-in-the-protist-model-organism-tetrahymena
#17
Anura Shodhan, Maria Novatchkova, Josef Loidl
Meiotic recombination is initiated by DNA double-strand breaks (DSBs). Most DSBs are converted into nonreciprocal exchanges (gene conversions) or crossovers (COs) between sister chromatids. Only a minority of DSBs are processed toward interhomolog COs, the precursors of the chiasmata that connect homologous chromosomes. Dmc1, the meiosis-specific paralog of the universal recombination protein Rad51, is required for interhomolog COs; in its absence, univalents are primarily formed. Here, we report a ciliate-specific novel meiotic gene, BIME2, which also promotes interhomolog crossing over...
August 12, 2017: Chromosome Research
https://www.readbyqxmd.com/read/28801461/structural-basis-of-human-prdm9-allele-c-specific-recognition-of-its-cognate-dna-sequence
#18
Anamika Patel, Xing Zhang, Robert M Blumenthal, Xiaodong Cheng
PRDM9 is the only mammalian gene that has been associated with speciation. The PR/SET domain 9 (PRDM9) protein is a major determinant of meiotic recombination hotspots, and acts through sequence-specific DNA binding via its C2H2 zinc finger (ZF) tandem array, which is highly polymorphic within and between species. The most common human variant, PRDM9 allele A (PRDM9a), contains 13 fingers (ZF1-13). Allele C (PRDM9c) is the second-most common among African populations, and differs from PRDM9a by an arginine-to-serine change (R764S) in ZF9, and by replacement of ZF11 with two other fingers, yielding 14 fingers in PRDM9c...
August 11, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28797117/analysis-of-the-impact-of-the-absence-of-rad51-strand-exchange-activity-in-arabidopsis-meiosis
#19
Gunjita Singh, Olivier Da Ines, Maria Eugenia Gallego, Charles I White
The ploidy of eukaryote gametes must be halved to avoid doubling of numbers of chromosomes with each generation and this is carried out by meiosis, a specialized cell division in which a single chromosomal replication phase is followed by two successive nuclear divisions. With some exceptions, programmed recombination ensures the proper pairing and distribution of homologous pairs of chromosomes in meiosis and recombination defects thus lead to sterility. Two highly related recombinases are required to catalyse the key strand-invasion step of meiotic recombination and it is the meiosis-specific DMC1 which is generally believed to catalyse the essential non-sister chromatid crossing-over, with RAD51 catalysing sister-chromatid and non-cross-over events...
2017: PloS One
https://www.readbyqxmd.com/read/28794107/variation-in-recombination-rate-and-its-genetic-determinism-in-sheep-populations
#20
Morgane Petit, Jean-Michel Astruc, Julien Sarry, Laurence Drouilhet, Stéphane Fabre, Carole Moreno, Bertrand Servin
Recombination is a complex biological process that results from a cascade of multiple events during meiosis. Understanding the genetic determinism of recombination can help to understand if and how these events are interacting. To tackle this question, we studied the patterns of recombination in sheep, using multiple approaches and datasets. We constructed male recombination maps in a dairy breed from the south of France (the Lacaune breed) at a fine scale by combining meiotic recombination rates from a large pedigree genotyped with a 50K SNP array and historical recombination rates from a sample of unrelated individuals genotyped with a 600K SNP array...
August 9, 2017: Genetics
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