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Homologous chromosome pairing

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https://www.readbyqxmd.com/read/28711872/cell-scientist-to-watch-kevin-corbett
#1
(no author information available yet)
Kevin Corbett graduated in biology and biochemistry from the University of Virginia. He then went to the University of California, Berkeley, to work on the structure and function of DNA topoisomerases in bacteria and archaea for his PhD with James Berger. In 2005, he moved to the laboratory of Stephen Harrison at Harvard Medical School for his postdoctoral work on kinetochore structure and function, particularly the yeast monopolin complex, which promotes proper chromosome segregation in the first meiotic division...
July 15, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28710064/time-course-analysis-of-early-meiotic-prophase-events-informs-mechanisms-of-homolog-pairing-and-synapsis-in-caenorhabditis-elegans
#2
Susanna Mlynarczyk-Evans, Anne M Villeneuve
Segregation of homologous chromosomes during meiosis depends on their ability to reorganize within the nucleus, discriminate among potential partners, and stabilize pairwise associations through assembly of the synaptonemal complex (SC). Here we report a high-resolution time-course analysis of these key early events during Caenorhabditis elegans meiosis. Labeled nucleotides are incorporated specifically into the X chromosomes during the last two hours of S phase, a property we exploit to identify a highly synchronous cohort of nuclei...
July 14, 2017: Genetics
https://www.readbyqxmd.com/read/28694245/fundamental-cell-cycle-kinases-collaborate-to-ensure-timely-destruction-of-the-synaptonemal-complex-during-meiosis
#3
Bilge Argunhan, Wing-Kit Leung, Negar Afshar, Yaroslav Terentyev, Vijayalakshmi V Subramanian, Yasuto Murayama, Andreas Hochwagen, Hiroshi Iwasaki, Tomomi Tsubouchi, Hideo Tsubouchi
The synaptonemal complex (SC) is a proteinaceous macromolecular assembly that forms during meiotic prophase I and mediates adhesion of paired homologous chromosomes along their entire lengths. Although prompt disassembly of the SC during exit from prophase I is a landmark event of meiosis, the underlying mechanism regulating SC destruction has remained elusive. Here, we show that DDK (Dbf4-dependent Cdc7 kinase) is central to SC destruction. Upon exit from prophase I, Dbf4, the regulatory subunit of DDK, directly associates with and is phosphorylated by the Polo-like kinase Cdc5...
July 10, 2017: EMBO Journal
https://www.readbyqxmd.com/read/28692038/par-terra-directs-homologous-sex-chromosome-pairing
#4
Hsueh-Ping Chu, John E Froberg, Barry Kesner, Hyun Jung Oh, Fei Ji, Ruslan Sadreyev, Stefan F Pinter, Jeannie T Lee
In mammals, homologous chromosomes rarely pair outside meiosis. One exception is the X chromosome, which transiently pairs during X-chromosome inactivation (XCI). How two chromosomes find each other in 3D space is not known. Here, we reveal a required interaction between the X-inactivation center (Xic) and the telomere in mouse embryonic stem (ES) cells. The subtelomeric, pseudoautosomal regions (PARs) of the two sex chromosomes (X and Y) also undergo pairing in both female and male cells. PARs transcribe a class of telomeric RNA, dubbed PAR-TERRA, which accounts for a vast majority of all TERRA transcripts...
July 10, 2017: Nature Structural & Molecular Biology
https://www.readbyqxmd.com/read/28681469/differential-expression-of-homologous-recombination-dna-repair-genes-in-the-early-and-advanced-stages-of-myelodysplastic-syndrome
#5
Jan Valka, Jitka Vesela, Hana Votavova, Michaela Dostalova-Merkerova, Zuzana Horakova, Vit Campr, Jana Brezinova, Zuzana Zemanova, Anna Jonasova, Jaroslav Cermak, Monika Belickova
BACKGROUND: The high incidence of mutations and cytogenetic abnormalities in patients with myelodysplastic syndrome (MDS) suggests that defects in DNA repair mechanisms. We monitored DNA repair pathways in MDS and their alterations during disease progression. METHODS: Expression profiling of DNA repair genes was performed on CD34+ cells and paired samples were used for monitoring of RAD51 and XRCC2 gene expression during disease progression. Immunohistochemical staining for RAD51 was done on histology samples...
July 5, 2017: European Journal of Haematology
https://www.readbyqxmd.com/read/28668977/organization-and-evolution-of-four-differentially-amplified-tandem-repeats-in-the-cucumis-hystrix-genome
#6
Shuqiong Yang, Xiaodong Qin, Chunyan Cheng, Ziang Li, Qunfeng Lou, Ji Li, Jinfeng Chen
Three subtelomeric satellites and one interstitial 5S rDNA were characterized in Cucumis hystrix, and the pericentromeric signals of two C. hystrix subtelomeric satellites along C. sativus chromosomes supported the hypothesis of chromosome fusion in Cucumis. Tandem repeats are chromosome structural fractions consisting of highly repetitive sequences organized in large tandem arrays in most eukaryotes. Differentiation of tandem repeats directly affects the chromosome structure, which contributes to species formation and evolution...
July 1, 2017: Planta
https://www.readbyqxmd.com/read/28668862/clinicopathological-characteristics-of-metaplastic-papillary-tumor-of-the-fallopian-tube
#7
M I Jang, Ji-Youn Sung, Ji-Ye Kim, Hyun-Soo Kim
Metaplastic papillary tumor (MPT) of the fallopian tube is a very uncommon lesion, displaying papillary growth of bland-appearing cells with abundant, eosinophilic cytoplasm and mucinous metaplasia. It is difficult for pathologists to determine whether to categorize this lesion as a metaplastic proliferative lesion or a true neoplasm. We recently experienced a case of tubal MPT and initiated a comprehensive review of previously published cases with thorough analysis of clinicopathological characteristics. MPT is typically related to pregnancy, but we describe the first case of pregnancy-unrelated, incidentally detected tubal MPT in a 51-year-old woman who underwent surgery for endometrial cancer...
July 2017: Anticancer Research
https://www.readbyqxmd.com/read/28667016/an-rna-recognition-motif-containing-protein-functions-in-meiotic-silencing-by-unpaired-dna
#8
Dilini A Samarajeewa, Pennapa Manitchotpisit, Miranda Henderson, Hua Xiao, David G Rehard, Kevin A Edwards, Patrick K T Shiu, Thomas M Hammond
Meiotic silencing by unpaired DNA (MSUD) is a biological process that searches pairs of homologous chromosomes (homologs) for segments of DNA that are unpaired. Genes found within unpaired segments are silenced for the duration of meiosis. In this report, we describe the identification and characterization of Neurospora crassa sad-7, a gene that encodes a protein with an RNA recognition motif. Orthologs of sad-7 are found in a wide range of ascomycete fungi. In N. crassa, sad-7 is required for a fully-efficient MSUD response to unpaired genes...
June 30, 2017: G3: Genes—Genomes—Genetics
https://www.readbyqxmd.com/read/28663070/poetry-in-motion-increased-chromosomal-mobility-after-dna-damage
#9
REVIEW
Michael J Smith, Rodney Rothstein
Double-strand breaks (DSBs) are among the most lethal DNA lesions, and a variety of pathways have evolved to manage their repair in a timely fashion. One such pathway is homologous recombination (HR), in which information from an undamaged donor site is used as a template for repair. Although many of the biochemical steps of HR are known, the physical movements of chromosomes that must underlie the pairing of homologous sequence during mitotic DSB repair have remained mysterious. Recently, several groups have begun to use a variety of genetic and cell biological tools to study this important question...
June 9, 2017: DNA Repair
https://www.readbyqxmd.com/read/28652620/differential-cohesin-loading-marks-paired-and-unpaired-regions-of-platypus-sex-chromosomes-at-prophase-i
#10
Aaron E Casey, Tasman J Daish, Jose Luis Barbero, Frank Grützner
Cohesins are vital for chromosome organisation during meiosis and mitosis. In addition to the important function in sister chromatid cohesion, these complexes play key roles in meiotic recombination, DSB repair, homologous chromosome pairing and segregation. Egg-laying mammals (monotremes) feature an unusually complex sex chromosome system, which raises fundamental questions about organisation and segregation during meiosis. We discovered a dynamic and differential accumulation of cohesins on sex chromosomes during platypus prophase I and specific reorganisation of the sex chromosome complex around a large nucleolar body...
June 26, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28646875/genome-analysis-of-diploscapter-coronatus-insights-into-molecular-peculiarities-of-a-nematode-with-parthenogenetic-reproduction
#11
Hideaki Hiraki, Hiroshi Kagoshima, Christopher Kraus, Philipp H Schiffer, Yumiko Ueta, Michael Kroiher, Einhard Schierenberg, Yuji Kohara
BACKGROUND: Sexual reproduction involving the fusion of egg and sperm is prevailing among eukaryotes. In contrast, the nematode Diploscapter coronatus, a close relative of the model Caenorhabditis elegans, reproduces parthenogenetically. Neither males nor sperm have been observed and some steps of meiosis are apparently skipped in this species. To uncover the genomic changes associated with the evolution of parthenogenesis in this nematode, we carried out a genome analysis. RESULTS: We obtained a 170 Mbp draft genome in only 511 scaffolds with a N50 length of 1 Mbp...
June 24, 2017: BMC Genomics
https://www.readbyqxmd.com/read/28642366/saccharomyces-cerevisiae-red1-protein-exhibits-nonhomologous-dna-end-joining-activity-and-potentiates-hop1-promoted-pairing-of-double-stranded-dna
#12
Rucha Kshirsagar, Indrajeet Ghodke, Kalappa Muniyappa
Elucidation of the function of synaptonemal complex (SC) in <Saccharomyces cerevisiae> has mainly focused on in vivo analysis of recombination-defective meiotic mutants. Consequently, significant gaps remain in the mechanistic understanding of the activities of different SC proteins and the functional relationships among them. S. cerevisiae Hop1 and Red1 are essential structural components of the SC axial/lateral elements. Previous studies have demonstrated that Hop1 is a structure-specific DNA-binding protein that exhibits high affinity for the Holliday junction, promotes DNA bridging, condensation and pairing between duplex DNA molecules...
June 22, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28640973/production-of-red-flowered-oilseed-rape-via-the-ectopic-expression-of-orychophragmus-violaceus-ovpap2
#13
Wenqin Fu, Daozong Chen, Qi Pan, Fengfeng Li, Zhigang Zhao, Xianhong Ge, Zaiyun Li
Oilseed rape (Brassica napus L.), which has yellow flowers, is both an important oil crop and a traditional tourism resource in China, whereas the Orychophragmus violaceus, which has purple flowers, likely possesses a candidate gene or genes to alter the flower color of oilseed rape. A previously established B. napus line has a particular pair of O. violaceus chromosomes (M4) and exhibits slightly red petals. In this study, the transcriptomic analysis of M4, B. napus (H3), and O. violaceus with purple petals (OvP) and with white petals (OvW) revealed that most anthocyanin biosynthesis genes were up-regulated in both M4 and OvP...
June 22, 2017: Plant Biotechnology Journal
https://www.readbyqxmd.com/read/28630130/how-a-genetically-stable-extremophile-evolves-modes-of-genome-diversification-in-the-archaeon-sulfolobus-acidocaldarius
#14
Dominic Mao, Dennis W Grogan
In order to analyze in molecular terms how Sulfolobus genomes diverge, damage-induced mutations and natural polymorphisms (PMs) were identified in laboratory constructs and wild-type isolates, respectively, of Sulfolobus acidocaldarius Among wild-type isolates drawn from one local population, pairwise nucleotide divergence averaged 4 x 10(-6), which is about 0.15% of the corresponding divergence reported for Sulfolobus islandicus The most variable features of wild-type S. acidocaldarius genomes were homopolymer (mononucleotide) tracts and longer tandem repeats, consistent with the spontaneous mutations that occur under laboratory conditions...
June 19, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28627638/meiotic-defects-and-decreased-expression-of-genes-located-around-the-chromosomal-breakpoint-in-the-testis-of-a-patient-with-a-novel-46-x-t-y-1-p11-3-p31-translocation
#15
Guangyuan Li, Furhan Iqbal, Liu Wang, Zhipeng Xu, Xiaoyan Che, Wen Yu, Liang Shi, Tonghang Guo, Guixiang Zhou, Xiaohua Jiang, Huan Zhang, Yuanwei Zhang, Dexin Yu
Balanced translocations are known to be associated with infertility, spontaneous abortions and birth defects in mammals. Spermatocyte spreading and immunostaining were applied to detect meiotic prophase I progression, homologous chromosome pairing, synapsis and recombination in an azoospermic reciprocal translocation 46,X,t(Y;1)(p11.3;p31) carrier. Histological examination of testicular sections revealed a severely reduced number of germ cells with no spermatids or sperm in the carrier. A significant reduction in XY recombination was observed in the patient...
June 14, 2017: International Journal of Molecular Medicine
https://www.readbyqxmd.com/read/28623274/reduction-in-chromosome-mobility-accompanies-nuclear-organization-during-early-embryogenesis-in-caenorhabditis-elegans
#16
Ritsuko Arai, Takeshi Sugawara, Yuko Sato, Yohei Minakuchi, Atsushi Toyoda, Kentaro Nabeshima, Hiroshi Kimura, Akatsuki Kimura
In differentiated cells, chromosomes are packed inside the cell nucleus in an organised fashion. In contrast, little is known about how chromosomes are packed in undifferentiated cells and how nuclear organization changes during development. To assess changes in nuclear organization during the earliest stages of development, we quantified the mobility of a pair of homologous chromosomal loci in the interphase nuclei of Caenorhabditis elegans embryos. The distribution of distances between homologous loci was consistent with a random distribution up to the 8-cell stage but not at later stages...
June 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28602622/homoeologous-chromosome-pairing-across-the-eukaryote-phylogeny
#17
REVIEW
Amanda L Grusz, Erin M Sigel, Colby Witherup
During the past quarter century, molecular phylogenetic inferences have significantly resolved evolutionary relationships spanning the eukaryotic tree of life. With improved phylogenies in hand, the focus of systematics will continue to expand from estimating species relationships toward examining the evolution of specific, fundamental traits across the eukaryotic tree. Undoubtedly, this will expose knowledge gaps in the evolution of key traits, particularly with respect to non-model lineages. Here, we examine one such trait across eukaryotes-the regulation of homologous chromosome pairing during meiosis-as an illustrative example...
June 8, 2017: Molecular Phylogenetics and Evolution
https://www.readbyqxmd.com/read/28591177/identification-and-characterization-of-constans-like-col-gene-family-in-upland-cotton-gossypium-hirsutum-l
#18
Darun Cai, Hui Liu, Na Sang, Xianzhong Huang
The CONSTANS/FLOWERING LOCUS T (CO/FT) regulon plays a central role in the control of flowering time in photoperiod-sensitive plants. Flowering time in wild cotton (Gossypium spp.) has strict photoperiod sensitivity, but domesticated cotton is day-neutral. Information on the molecular characterization of the CO and CO-like (COL) genes in cotton is very limited. In this study, we identified 42 COL homologs (GhCOLs) in the G. hirsutum genome, and many of them were previously unreported. We studied their chromosome distribution, phylogenetic relationships, and structures of genes and proteins...
2017: PloS One
https://www.readbyqxmd.com/read/28590593/the-proteasome-enters-the-meiotic-prophase-fray
#19
REVIEW
Aleksandar Vujin, Monique Zetka
The segregation of homologous chromosomes in meiosis depends on their ability to locate one another in the nucleus and establish a physical association through crossing over. A tightly regulated number of crossovers (COs) emerges following repair of induced DNA double-strand breaks by homologous recombination (HR), but the process of how HR intermediates transition into COs is still poorly understood. Two recent studies by Ahuja et al. and Rao et al. have revealed a role for chromosomally localized proteasomes in choreographing both homologous chromosome pairing and the evolution of HR intermediates into segregation-competent COs...
June 7, 2017: BioEssays: News and Reviews in Molecular, Cellular and Developmental Biology
https://www.readbyqxmd.com/read/28588601/in-favor-of-establishment-regulation-of-chromatid-cohesion-in-plants
#20
REVIEW
Pablo Bolaños-Villegas, Kuntal De, Mónica Pradillo, Desheng Liu, Christopher A Makaroff
In eukaryotic organisms, the correct regulation of sister chromatid cohesion, whereby sister chromatids are paired and held together, is essential for accurate segregation of the sister chromatids and homologous chromosomes into daughter cells during mitosis and meiosis, respectively. Sister chromatid cohesion requires a cohesin complex comprised of structural maintenance of chromosome adenosine triphosphatases and accessory proteins that regulate the association of the complex with chromosomes or that are involved in the establishment or release of cohesion...
2017: Frontiers in Plant Science
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