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Homologous chromosome pairing

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https://www.readbyqxmd.com/read/29141207/distinct-terb1-domains-regulate-different-protein-interactions-in-meiotic-telomere-movement
#1
Jingjing Zhang, Zhaowei Tu, Yoshinori Watanabe, Hiroki Shibuya
Meiotic telomeres attach to the nuclear envelope (NE) and drive the chromosome movement required for the pairing of homologous chromosomes. The meiosis-specific telomere proteins TERB1, TERB2, and MAJIN are required to regulate these events, but their assembly processes are largely unknown. Here, we developed a germ-cell-specific knockout mouse of the canonical telomere-binding protein TRF1 and revealed an essential role for TRF1 in directing the assembly of TERB1-TERB2-MAJIN. Further, we identified a TERB2 binding (T2B) domain in TERB1 that is dispensable for the TRF1-TERB1 interaction but is essential for the subsequent TERB1-TERB2 interaction and therefore for telomere attachment to the NE...
November 14, 2017: Cell Reports
https://www.readbyqxmd.com/read/29124392/tracking-the-evolutionary-pathway-of-sex-chromosomes-among-fishes-characterizing-the-unique-xx-xy1y2-system-in-hoplias-malabaricus-teleostei-characiformes
#2
Ezequiel Aguiar de Oliveira, Alexandr Sember, Luiz Antonio Carlos Bertollo, Cassia Fernanda Yano, Tariq Ezaz, Orlando Moreira-Filho, Terumi Hatanaka, Vladimir Trifonov, Thomas Liehr, Ahmed Basheer Hamid Al-Rikabi, Petr Ráb, Hugmar Pains, Marcelo de Bello Cioffi
The Neotropical fish, Hoplias malabaricus, is one of the most cytogenetically studied fish taxon with seven distinct karyomorphs (A-G) comprising varying degrees of sex chromosome differentiation, ranging from homomorphic to highly differentiated simple and multiple sex chromosomes. Therefore, this fish offers a unique opportunity to track evolutionary mechanisms standing behind the sex chromosome evolution and differentiation. Here, we focused on a high-resolution cytogenetic characterization of the unique XX/XY1Y2 multiple sex chromosome system found in one of its karyomorphs (G)...
November 9, 2017: Chromosoma
https://www.readbyqxmd.com/read/29123917/the-telomere-bouquet-facilitates-meiotic-prophase-progression-and-exit-in-fission-yeast
#3
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
https://www.readbyqxmd.com/read/29109224/low-recombination-rates-in-sexual-species-and-sex-asex-transitions
#4
Christoph R Haag, Loukas Theodosiou, Roula Zahab, Thomas Lenormand
In most sexual, diploid eukaryotes, at least one crossover occurs between each pair of homologous chromosomes during meiosis, presumably in order to ensure proper segregation. Well-known exceptions to this rule are species in which one sex does not recombine and specific chromosomes lacking crossover. We review other possible exceptions, including species with chromosome maps of less than 50 cM in one or both sexes. We discuss the idea that low recombination rates may favour sex-asex transitions, or, alternatively may be a consequence of it...
December 19, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/29096605/genome-wide-identification-and-expression-analysis-of-calmodulin-like-cml-genes-in-chinese-cabbage-brassica-rapa-l-ssp-pekinensis
#5
Shanshan Nie, Minjuan Zhang, Lugang Zhang
BACKGROUND: Calmodulin-like (CML) proteins are a primary family of plant-specific Ca(2+) sensors that specifically bind to Ca(2+) and deliver a Ca(2+) signal. CML proteins have been identified and characterized in many plant species, such as the model plant Arabidopsis and rice. Based on considerable evidence, the roles of CML proteins are crucial in plant growth and development and in the response to various external stimuli. Nevertheless, the characterization and expression profiling of CML genes in Chinese cabbage (Brassica rapa L...
November 2, 2017: BMC Genomics
https://www.readbyqxmd.com/read/29084138/chromosome-evolution-in-the-free-living-flatworms-first-evidence-of-intrachromosomal-rearrangements-in-karyotype-evolution-of-macrostomum-lignano-platyhelminthes-macrostomida
#6
Kira S Zadesenets, Nikita I Ershov, Eugene Berezikov, Nikolay B Rubtsov
The free-living flatworm Macrostomum lignano is a hidden tetraploid. Its genome was formed by a recent whole genome duplication followed by chromosome fusions. Its karyotype (2n = 8) consists of a pair of large chromosomes (MLI1), which contain regions of all other chromosomes, and three pairs of small metacentric chromosomes. Comparison of MLI1 with metacentrics was performed by painting with microdissected DNA probes and fluorescent in situ hybridization of unique DNA fragments. Regions of MLI1 homologous to small metacentrics appeared to be contiguous...
October 30, 2017: Genes
https://www.readbyqxmd.com/read/29083416/telomeric-terb1-trf1-interaction-is-crucial-for-male-meiosis
#7
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
https://www.readbyqxmd.com/read/29083414/dissecting-the-telomere-inner-nuclear-membrane-interface-formed-in-meiosis
#8
Devon F Pendlebury, Yasuhiro Fujiwara, Valerie M Tesmer, Eric M Smith, Hiroki Shibuya, Yoshinori Watanabe, Jayakrishnan Nandakumar
Tethering telomeres to the inner nuclear membrane (INM) allows homologous chromosome pairing during meiosis. The meiosis-specific protein TERB1 binds the telomeric protein TRF1 to establish telomere-INM connectivity and is essential for mouse fertility. Here we solve the structure of the human TRF1-TERB1 interface to reveal the structural basis for telomere-INM linkage. Disruption of this interface abrogates binding and compromises telomere-INM attachment in mice. An embedded CDK-phosphorylation site within the TRF1-binding region of TERB1 provides a mechanism for cap exchange, a late-pachytene phenomenon involving the dissociation of the TRF1-TERB1 complex...
October 30, 2017: Nature Structural & Molecular Biology
https://www.readbyqxmd.com/read/29078313/ultraaccurate-genome-sequencing-and-haplotyping-of-single-human-cells
#9
Wai Keung Chu, Peter Edge, Ho Suk Lee, Vikas Bansal, Vineet Bafna, Xiaohua Huang, Kun Zhang
Accurate detection of variants and long-range haplotypes in genomes of single human cells remains very challenging. Common approaches require extensive in vitro amplification of genomes of individual cells using DNA polymerases and high-throughput short-read DNA sequencing. These approaches have two notable drawbacks. First, polymerase replication errors could generate tens of thousands of false-positive calls per genome. Second, relatively short sequence reads contain little to no haplotype information. Here we report a method, which is dubbed SISSOR (single-stranded sequencing using microfluidic reactors), for accurate single-cell genome sequencing and haplotyping...
October 24, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29069730/inhibition-of-colorectal-cancer-genomic-copy-number-alterations-and-chromosomal-fragile-site-tumor-suppressor-fhit-and-wwox-deletions-by-dna-mismatch-repair
#10
Sohail Jahid, Jian Sun, Ozkan Gelincik, Pedro Blecua, Winfried Edelmann, Raju Kucherlapati, Kathy Zhou, Maria Jasin, Zeynep H Gümüş, Steven M Lipkin
Homologous recombination (HR) enables precise DNA repair after DNA double strand breaks (DSBs) using identical sequence templates, whereas homeologous recombination (HeR) uses only partially homologous sequences. Homeologous recombination introduces mutations through gene conversion and genomic deletions through single-strand annealing (SSA). DNA mismatch repair (MMR) inhibits HeR, but the roles of mammalian MMR MutL homologues (MLH1, PMS2 and MLH3) proteins in HeR suppression are poorly characterized. Here, we demonstrate that mouse embryonic fibroblasts (MEFs) carrying Mlh1, Pms2, and Mlh3 mutations have higher HeR rates, by using 7,863 uniquely mapping paired direct repeat sequences (DRs) in the mouse genome as endogenous gene conversion and SSA reporters...
September 22, 2017: Oncotarget
https://www.readbyqxmd.com/read/29055804/high-homology-is-not-required-at-the-site-of-strand-invasion-during-recombinational-double-strand-break-repair-in-mammalian-chromosomes
#11
Kristina M Chapman, Megan M Wilkey, Kendall E Potter, Barbara C Waldman, Alan S Waldman
We investigated the impact of sequence divergence on DNA double-strand break (DSB) repair occurring via recombination in cultured thymidine kinase deficient mouse fibroblasts. We stably transfected cells with a DNA construct harboring a herpes thymidine kinase (tk) gene (the "recipient") rendered nonfunctional by insertion of an oligonucleotide containing the recognition site for endonuclease I-SceI. The construct also contained a closely linked truncated "donor" tk sequence. The donor could potentially restore function to the recipient gene via recombination provoked by induction of a DSB at the I-SceI site in the recipient...
October 16, 2017: DNA Repair
https://www.readbyqxmd.com/read/29053571/chromosome-synapsis-and-recombination-in-male-hybrids-between-two-chromosome-races-of-the-common-shrew-sorex-araneus-l-soricidae-eulipotyphla
#12
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
https://www.readbyqxmd.com/read/29052098/comparative-transcriptome-analysis-reveals-whole-genome-duplications-and-gene-selection-patterns-in-cultivated-and-wild-chrysanthemum-species
#13
So Youn Won, Soo-Jin Kwon, Tae-Ho Lee, Jae-A Jung, Jung Sun Kim, Sang-Ho Kang, Seong-Han Sohn
Comparative transcriptome analysis of wild and cultivated chrysanthemums provides valuable genomic resources and helps uncover common and divergent patterns of genome and gene evolution in these species. Plants are unique in that they employ polyploidy (or whole-genome duplication, WGD) as a key process for speciation and evolution. The Chrysanthemum genus is closely associated with hybridization and polyploidization, with Chrysanthemum species exhibiting diverse ploidy levels. The commercially important species, C...
October 19, 2017: Plant Molecular Biology
https://www.readbyqxmd.com/read/29032424/not-just-gene-expression-3d-implications-of-chromatin-modifications-during-sexual-plant-reproduction
#14
Stefanie Dukowic-Schulze, Chang Liu, Changbin Chen
DNA methylation and histone modifications are epigenetic changes on a DNA molecule that alter the three-dimensional (3D) structure locally as well as globally, impacting chromatin looping and packaging on a larger scale. Epigenetic marks thus inform higher-order chromosome organization and placement in the nucleus. Conventional epigenetic marks are joined by chromatin modifiers like cohesins, condensins and membrane-anchoring complexes to support particularly 3D chromosome organization. The most popular consequences of epigenetic modifications are gene expression changes, but chromatin modifications have implications beyond this, particularly in actively dividing cells and during sexual reproduction...
October 14, 2017: Plant Cell Reports
https://www.readbyqxmd.com/read/29030445/microhomology-mediated-high-throughput-gene-inactivation-strategy-for-hyperthermophilic-crenarchaeon-sulfolobus-islandicus
#15
Changyi Zhang, Rachel J Whitaker
Sulfolobus islandicus is rapidly emerging as a model system for studying the biology and evolution within the TACK lineage of the Archaeal domain. As the tree of life grows, identifying the cellular function of genes within this lineage will have significant impacts on our understanding of the evolution of Last Archaeal Eukaryote Common Ancestor (LEACA) and the differentiation of Archaea from Eukaryotes during the evolution of the modernday cell. To progress our understanding of this key Archaeal organism, we report a novel high-throughput method for targeted gene inactivation in S...
October 13, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29021693/a-refined-panax-ginseng-karyotype-based-on-an-ultra-high-copy-167-bp-tandem-repeat-and-ribosomal-dnas
#16
Nomar Espinosa Waminal, Hong-Il Choi, Nam-Hoon Kim, Woojong Jang, Junki Lee, Jee Young Park, Hyun Hee Kim, Tae-Jin Yang
BACKGROUND: Panax ginseng Meyer (Asian ginseng) has a large nuclear genome size of > 3.5 Gbp in haploid genome equivalent of 24 chromosomes. Tandem repeats (TRs) occupy significant portions of the genome in many plants and are often found in specific genomic loci, making them a valuable molecular cytogenetic tool in discriminating chromosomes. In an effort to understand the P. ginseng genome structure, we characterized an ultrahigh copy 167-bp TR (Pg167TR) and explored its chromosomal distribution as well as its utility for chromosome identification...
October 2017: Journal of Ginseng Research
https://www.readbyqxmd.com/read/29021238/asy2-mer2-an-evolutionarily-conserved-mediator-of-meiotic-recombination-pairing-and-global-chromosome-compaction
#17
Sophie Tessé, Henri-Marc Bourbon, Robert Debuchy, Karine Budin, Emeline Dubois, Zhang Liangran, Romain Antoine, Tristan Piolot, Nancy Kleckner, Denise Zickler, Eric Espagne
Meiosis is the cellular program by which a diploid cell gives rise to haploid gametes for sexual reproduction. Meiotic progression depends on tight physical and functional coupling of recombination steps at the DNA level with specific organizational features of meiotic-prophase chromosomes. The present study reveals that every step of this coupling is mediated by a single molecule: Asy2/Mer2. We show that Mer2, identified so far only in budding and fission yeasts, is in fact evolutionarily conserved from fungi (Mer2/Rec15/Asy2/Bad42) to plants (PRD3/PAIR1) and mammals (IHO1)...
September 15, 2017: Genes & Development
https://www.readbyqxmd.com/read/28993668/non-mendelian-assortment-of-homologous-autosomes-of-different-sizes-in-males-is-the-ancestral-state-in-the-caenorhabditis-lineage
#18
Tho Son Le, Fang-Jung Yang, Yun-Hua Lo, Tiffany C Chang, Jung-Chen Hsu, Chia-Yi Kao, John Wang
Organismal genome sizes vary by six orders of magnitude and appear positively correlated with organismal size and complexity. Neutral models have been proposed to explain the broad patterns of genome size variation based on organism population sizes. In the Caenorhabditis genus, hermaphrodite genomes are smaller than those of gonochoristic species. One possible driving force for this genome size difference could be non-random chromosome segregation. In Caenorhabditis elegans, chromosome assortment is non-independent and violates Mendel's second law...
October 9, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28992351/modification-of-meiotic-recombination-by-natural-variation-in-plants
#19
Emma J Lawrence, Catherine H Griffin, Ian R Henderson
Meiosis is a specialized cell division that produces haploid gametes required for sexual reproduction. During the first meiotic division, homologous chromosomes pair and undergo reciprocal crossing over, which recombines linked sequence variation. Meiotic recombination frequency varies extensively both within and between species. In this review, we will examine the molecular basis of meiotic recombination rate variation, with an emphasis on plant genomes. We first consider cis modification caused by polymorphisms at the site of recombination, or elsewhere on the same chromosome...
September 6, 2017: Journal of Experimental Botany
https://www.readbyqxmd.com/read/28969795/legume-isoflavone-synthase-genes-have-evolved-by-whole-genome-and-local-duplications-yielding-transcriptionally-active-paralogs
#20
Dorota Narożna, Michał Książkiewicz, Łucja Przysiecka, Joanna Króliczak, Bogdan Wolko, Barbara Naganowska, Cezary J Mądrzak
Isoflavone synthase (IFS) is the key enzyme of isoflavonoid biosynthesis. IFS genes were identified in numerous species, although their evolutionary patterns have not yet been reconstructed. To address this issue, we performed structural and functional genomic analysis. Narrow leafed lupin, Lupinus angustifolius L., was used as a reference species for the genus, because it has the most developed molecular tools available. Nuclear genome BAC library clones carrying IFS homologs were localized by linkage mapping and fluorescence in situ hybridization in three chromosome pairs...
November 2017: Plant Science: An International Journal of Experimental Plant Biology
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