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https://www.readbyqxmd.com/read/27918550/selective-y-centromere-inactivation-triggers-chromosome-shattering-in-micronuclei-and-repair-by-non-homologous-end-joining
#1
Peter Ly, Levi S Teitz, Dong H Kim, Ofer Shoshani, Helen Skaletsky, Daniele Fachinetti, David C Page, Don W Cleveland
Chromosome missegregation into a micronucleus can cause complex and localized genomic rearrangements known as chromothripsis, but the underlying mechanisms remain unresolved. Here we developed an inducible Y centromere-selective inactivation strategy by exploiting a CENP-A/histone H3 chimaera to directly examine the fate of missegregated chromosomes in otherwise diploid human cells. Using this approach, we identified a temporal cascade of events that are initiated following centromere inactivation involving chromosome missegregation, fragmentation, and re-ligation that span three consecutive cell cycles...
December 5, 2016: Nature Cell Biology
https://www.readbyqxmd.com/read/27917322/bioinformatical-analysis-of-eukaryotic-shugoshins-reveals-meiosis-specific-features-of-vertebrate-shugoshins
#2
Tatiana M Grishaeva, Darya Kulichenko, Yuri F Bogdanov
BACKGROUND: Shugoshins (SGOs) are proteins that protect cohesins located at the centromeres of sister chromatids from their early cleavage during mitosis and meiosis in plants, fungi, and animals. Their function is to prevent premature sister-chromatid disjunction and segregation. The study focused on the structural differences among SGOs acting during mitosis and meiosis that cause differences in chromosome behavior in these two types of cell division in different organisms. METHODS: A bioinformatical analysis of protein domains, conserved amino acid motifs, and physicochemical properties of 32 proteins from 25 species of plants, fungi, and animals was performed...
2016: PeerJ
https://www.readbyqxmd.com/read/27913618/meiotic-centromere-coupling-and-pairing-function-by-two-separate-mechanisms-in-saccharomyces-cerevisiae
#3
Emily L Kurdzo, David Obeso, Hoa Chuong, Dean S Dawson
In meiosis I, chromosomes become paired with their homologous partners and then are pulled towards opposite poles of the spindle. In the budding yeast, Saccharomyces cerevisiae, in early meiotic prophase, centromeres are observed to associate in pairs in a homology-independent manner, a process called centromere coupling. Later, as homologous chromosomes align, their centromeres associate in a process called centromere pairing. The synaptonemal complex protein Zip1 is necessary for both types of centromere association...
December 2, 2016: Genetics
https://www.readbyqxmd.com/read/27912109/characterization-and-fine-mapping-of-a-novel-premature-leaf-senescence-mutant-yellow-leaf-and-dwarf-1-in-rice
#4
Luchang Deng, Peng Qin, Zhi Liu, Geling Wang, Weilan Chen, Jianhua Tong, Langtao Xiao, Bin Tu, Yuantao Sun, Wei Yan, Hang He, Jun Tan, Xuewei Chen, Yuping Wang, Shigui Li, Bingtian Ma
Leaves are the main organs in which photosynthates are produced. Leaf senescence facilitates the translocation of photosynthates and nutrients from source to sink, which is important for plant development and especially for crop yield. However, the molecular mechanism of leaf senescence is unknown. Here, we identified a mutant, yellow leaf and dwarf 1 (yld1), which exhibited decreased plant height and premature leaf senescence. Nitroblue tetrazolium and diamiobenzidine staining analyses revealed that the concentrations of reactive oxygen species were higher in yld1 leaves than in wild type leaves...
November 22, 2016: Plant Physiology and Biochemistry: PPB
https://www.readbyqxmd.com/read/27911702/the-unconventional-kinetoplastid-kinetochore-from-discovery-toward-functional-understanding
#5
REVIEW
Bungo Akiyoshi
The kinetochore is the macromolecular protein complex that drives chromosome segregation in eukaryotes. Its most fundamental function is to connect centromeric DNA to dynamic spindle microtubules. Studies in popular model eukaryotes have shown that centromere protein (CENP)-A is critical for DNA-binding, whereas the Ndc80 complex is essential for microtubule-binding. Given their conservation in diverse eukaryotes, it was widely believed that all eukaryotes would utilize these components to make up a core of the kinetochore...
October 15, 2016: Biochemical Society Transactions
https://www.readbyqxmd.com/read/27910025/cytogenetics-for-biological-dosimetry
#6
Michelle Ricoul, Tamizh Gnana-Sekaran, Laure Piqueret-Stephan, Laure Sabatier
Cytogenetics is the gold-standard in biological dosimetry for assessing a received dose of ionizing radiation. More modern techniques have recently emerged, but none are as specific as cytogenetic approaches, particularly the dicentric assay. Here, we will focus on the principal cytogenetic techniques used for biological dosimetry: the dicentric assay in metaphase cells, the micronuclei assay in binucleated cells, and the premature condensed chromosome (PCC) assay in interphase cells. New fluorescence in situ hybridization (FISH) techniques (such as telomere-centromere hybridization) have facilitated the analysis of the dicentric assay and have permitted to assess the dose a long time after irradiation by translocation analysis (such as by Tri-color FISH or Multiplex-FISH)...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/27910014/chromosome-bandings
#7
Huifang Huang, Jiadi Chen
Chromosome banding is an essential technique used in chromosome karyotyping to identify normal and abnormal chromosomes for clinical and research purposes. Giemsa (G)-, reverse (R)-, and centromere (C)-banding are the most commonly dye-based chromosome-banding techniques. G-banding involves the staining of trypsin-treated chromosomes and R-banding involves denaturing in hot acidic saline followed by Giemsa staining. C-banding is specifically used for identifying heterochromatin by denaturing chromosomes in a saturated alkaline solution followed by Giemsa staining...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/27899719/a-novel-hypothesis-for-histone-to-protamine-transition-in-bos-taurus-spermatozoa
#8
Gerly Sillaste, Lauris Kaplinski, Riho Meier, Ülle Jaakma, Elo Eriste, Andres Salumets
DNA compaction with protamines in sperm is essential for successful fertilization. However, a portion of sperm chromatin remains less tightly packed with histones, which genomic location and function remain unclear. We extracted and sequenced histone-associated DNA from sperm of nine ejaculates from three bulls. We found that the fraction of retained histones varied between samples but the variance was similar between samples from the same and different individuals. The most conserved regions showed similar abundance across all samples, while in other regions their presence correlated with the size of histone fraction...
November 29, 2016: Reproduction: the Official Journal of the Society for the Study of Fertility
https://www.readbyqxmd.com/read/27899648/genetic-selection-for-mistranslation-rescues-a-defective-co-chaperone-in-yeast
#9
Kyle S Hoffman, Matthew D Berg, Brian H Shilton, Christopher J Brandl, Patrick O'Donoghue
Despite the general requirement for translation fidelity, mistranslation can be an adaptive response. We selected spontaneous second site mutations that suppress the stress sensitivity caused by a Saccharomyces cerevisiae tti2 allele with a Leu to Pro mutation at residue 187, identifying a single nucleotide mutation at the same position (C70U) in four tRNA(Pro)UGG genes. Linkage analysis and suppression by SUF9G3:U70 expressed from a centromeric plasmid confirmed the causative nature of the suppressor mutation...
November 28, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27894815/the-histone-variant-h3-3-in-transcriptional-regulation-and-human-disease
#10
REVIEW
Leilei Shi, Hong Wen, Xiaobing Shi
Histone proteins wrap around DNA to form nucleosomes, which further compact into higher order structure of chromatin. In addition to the canonical histones, there are also variant histones that often have pivotal roles in regulating chromatin dynamics and the accessibility of the underlying DNA. H3.3 is the most common non-centromeric variant of histone H3 that differs from the canonical H3 by just 4-5 amino acids. Here we discuss the current knowledge of H3.3 in transcriptional regulation and the recent discoveries and molecular mechanisms of H3...
November 25, 2016: Journal of Molecular Biology
https://www.readbyqxmd.com/read/27894682/molecular-mechanisms-by-which-in-vivo-exposure-to-exogenous-chemical-genotoxic-agents-can-lead-to-micronucleus-formation-in-lymphocytes-in-vivo-and-ex-vivo-in-humans
#11
REVIEW
Michael Fenech, Siegfried Knasmueller, Claudia Bolognesi, Stefano Bonassi, Nina Holland, Lucia Migliore, Fabrizio Palitti, Adayapalam T Natarajan, Micheline Kirsch-Volders
The purpose of this review is to summarise current knowledge on the molecular mechanisms by which in vivo exposure to exogenous chemical genotoxins in humans induces micronuclei (MNi) and other nuclear anomalies in lymphocytes in vivo and ex vivo after nuclear division in vitro. MNi originate from acentric chromosome fragments and/or whole chromosomes that are unable to engage with the mitotic spindle and/or fail to segregate properly to the daughter nuclei during anaphase. The lagging fragments or whole chromosomes are surrounded by membrane and become MNi...
October 2016: Mutation Research
https://www.readbyqxmd.com/read/27893298/replication-checkpoint-suppression-and-structure-of-centromeric-dna
#12
Francesco Romeo, Lucia Falbo, Vincenzo Costanzo
Human centromeres contain large amounts of repetitive DNA sequences known as α satellite DNA, which can be difficult to replicate and whose functional role is unclear. Recently, we have characterized protein composition, structural organization and checkpoint response to stalled replication forks of centromeric chromatin reconstituted in Xenopus laevis egg extract. We showed that centromeric DNA has high affinity for SMC2-4 subunits of condensins and for CENP-A, it is enriched for DNA repair factors and suppresses the ATR checkpoint to ensure its efficient replication...
November 28, 2016: Nucleus
https://www.readbyqxmd.com/read/27890612/in%C3%A2-vitro-reconstitution-and-biochemical-analyses-of-the-schizosaccharomyces-pombe-nucleosome
#13
Masako Koyama, Wataru Nagakura, Hiroki Tanaka, Tomoya Kujirai, Yuji Chikashige, Tokuko Haraguchi, Yasushi Hiraoka, Hitoshi Kurumizaka
Schizosaccharomyces pombe, which has a small genome but shares many physiological functions with higher eukaryotes, is a useful single-cell, model eukaryotic organism. In particular, many features concerning chromatin structure and dynamics, including heterochromatin, centromeres, telomeres, and DNA replication origins, are well conserved between S. pombe and higher eukaryotes. However, the S. pombe nucleosome, the fundamental structural unit of chromatin, has not been reconstituted in vitro. In the present study, we established the method to purify S...
November 24, 2016: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/27889481/mitotic-nuclear-envelope-breakdown-and-spindle-nucleation-are-controlled-by-interphase-contacts-between-centromeres-and-the-nuclear-envelope
#14
Alfonso Fernández-Álvarez, Cécile Bez, Eileen T O'Toole, Mary Morphew, Julia Promisel Cooper
Faithful genome propagation requires coordination between nuclear envelope (NE) breakdown, spindle formation, and chromosomal events. The conserved linker of nucleoskeleton and cytoskeleton (LINC) complex connects fission yeast centromeres and the centrosome, across the NE, during interphase. During meiosis, LINC connects the centrosome with telomeres rather than centromeres. We previously showed that loss of telomere-LINC contacts compromises meiotic spindle formation. Here, we define the precise events regulated by telomere-LINC contacts and address the analogous possibility that centromeres regulate mitotic spindle formation...
November 22, 2016: Developmental Cell
https://www.readbyqxmd.com/read/27881713/gtse1-tunes-microtubule-stability-for-chromosome-alignment-and-segregation-by-inhibiting-the-microtubule-depolymerase-mcak
#15
Shweta Bendre, Arnaud Rondelet, Conrad Hall, Nadine Schmidt, Yu-Chih Lin, Gary J Brouhard, Alexander W Bird
The dynamic regulation of microtubules (MTs) during mitosis is critical for accurate chromosome segregation and genome stability. Cancer cell lines with hyperstabilized kinetochore MTs have increased segregation errors and elevated chromosomal instability (CIN), but the genetic defects responsible remain largely unknown. The MT depolymerase MCAK (mitotic centromere-associated kinesin) can influence CIN through its impact on MT stability, but how its potent activity is controlled in cells remains unclear. In this study, we show that GTSE1, a protein found overexpressed in aneuploid cancer cell lines and tumors, regulates MT stability during mitosis by inhibiting MCAK MT depolymerase activity...
December 5, 2016: Journal of Cell Biology
https://www.readbyqxmd.com/read/27881300/structure-of-the-mind-complex-defines-a-regulatory-focus-for-yeast-kinetochore-assembly
#16
Yoana N Dimitrova, Simon Jenni, Roberto Valverde, Yadana Khin, Stephen C Harrison
Kinetochores connect centromeric nucleosomes with mitotic-spindle microtubules through conserved, cross-interacting protein subassemblies. In budding yeast, the heterotetrameric MIND complex (Mtw1, Nnf1, Nsl1, Dsn1), ortholog of the metazoan Mis12 complex, joins the centromere-proximal components, Mif2 and COMA, with the principal microtubule-binding component, the Ndc80 complex (Ndc80C). We report the crystal structure of Kluyveromyces lactis MIND and examine its partner interactions, to understand the connection from a centromeric nucleosome to a much larger microtubule...
November 3, 2016: Cell
https://www.readbyqxmd.com/read/27880912/cenp-a-is-dispensable-for-mitotic-centromere-function-after-initial-centromere-kinetochore-assembly
#17
Sebastian Hoffmann, Marie Dumont, Viviana Barra, Peter Ly, Yael Nechemia-Arbely, Moira A McMahon, Solène Hervé, Don W Cleveland, Daniele Fachinetti
Human centromeres are defined by chromatin containing the histone H3 variant CENP-A assembled onto repetitive alphoid DNA sequences. By inducing rapid, complete degradation of endogenous CENP-A, we now demonstrate that once the first steps of centromere assembly have been completed in G1/S, continued CENP-A binding is not required for maintaining kinetochore attachment to centromeres or for centromere function in the next mitosis. Degradation of CENP-A prior to kinetochore assembly is found to block deposition of CENP-C and CENP-N, but not CENP-T, thereby producing defective kinetochores and failure of chromosome segregation...
November 22, 2016: Cell Reports
https://www.readbyqxmd.com/read/27879390/phosphorylation-of-map65-1-by-arabidopsis-aurora-kinases-is-required-for-efficient-cell-cycle-progression
#18
Joanna Boruc, Annika Weimer, Virginie Stoppin-Mellet, Evelien Mylle, Ken Kosetsu, Cesyen Cedeno, Michel Jaquinod, Maria Njo, Liesbeth De Milde, Peter Tompa, Nathalie Gonzalez, Dirk Inze, Tom Beeckman, Marylin Vantard, Daniel van Damme
Aurora kinases are key effectors of mitosis. Plant Auroras are functionally divided into two clades. The α Auroras (Aurora1 and Aurora2) associate with the spindle and the cell plate and are implicated in controlling formative divisions throughout plant development. The β Aurora (Aurora3) localizes to centromeres and likely functions in chromosome separation. In contrast to the wealth of data available on the role of Aurora in other kingdoms, knowledge on their function in plants is merely emerging. This is exemplified by the fact that only histone H3 and the plant homologue of TPX2 have been identified as Aurora substrates in plants...
November 22, 2016: Plant Physiology
https://www.readbyqxmd.com/read/27871933/a-molecular-prospective-for-hira-complex-assembly-and-h3-3-specific-histone-chaperone-function
#19
REVIEW
M Daniel Ricketts, Ronen Marmorstein
Incorporation of variant histone sequences, in addition to post-translational modification of histones, serves to modulate the chromatin environment. Different histone chaperone proteins mediate the storage and chromatin deposition of variant histones. Although the two non-centromeric histone H3 variants, H3.1 and H3.3, differ by only 5 aa, replacement of histone H3.1 with H3.3 can modulate the transcription for highly expressed and developmentally required genes, lead to the formation of repressive heterochromatin, or aid in DNA and chromatin repair...
November 19, 2016: Journal of Molecular Biology
https://www.readbyqxmd.com/read/27866013/a-whole-genome-gene-content-phylogenetic-analysis-of-anopheline-mosquitoes
#20
Jeffrey A Rosenfeld, Sara Oppenheim, Rob DeSalle
Construction of stringent gene content matrices was accomplished for 21 Anopheline mosquito species and strains and four outgroups species. The presence absence matrix using e(-75) as a cutoff in single linkage clustering had over 17,000 ortholog groups. We used the gene content matrix to generate a phylogenetic hypothesis that is in general agreement with gene sequence based phylogenies. In addition to establishing a congruent gene content phylogeny we examined the consistency of three methods for analyzing presence absence data - unweighted parsimony, dollo parsimonly and maximum likelihood using a BINGAMMA model...
November 16, 2016: Molecular Phylogenetics and Evolution
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