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chromosome condensation

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https://www.readbyqxmd.com/read/28914393/costunolide-induces-micronuclei-formation-chromosomal-aberrations-cytostasis-and-mitochondrial-mediated-apoptosis-in-chinese-hamster-ovary-cells
#1
Soma Shiva Nageswara Rao Singireesu, Sunil Misra, Sujan Kumar Mondal, Suresh Yerramsetty, Nivedita Sahu, Suresh Babu K
Costunolide (CE) is a sesquiterpene lactone well-known for its antihepatotoxic, antiulcer, and anticancer activities. The present study focused on the evaluation of the cytogenetic toxicity and cellular death-inducing potential of CE in CHO cells, an epithelial cell line derived from normal ovary cells of Chinese hamster. The cytotoxic effect denoting MTT assay has shown an IC50 value of 7.56 μM CE, where 50% proliferation inhibition occurs. The oxidative stress caused by CE was confirmed based on GSH depletion induced cell death, conspicuously absent in N-acetylcysteine (GSH precursor) pretreated cells...
September 15, 2017: Cell Biology and Toxicology
https://www.readbyqxmd.com/read/28903997/mitotic-post-translational-modifications-of-histones-promote-chromatin-compaction-in-vitro
#2
Alisa Zhiteneva, Juan Jose Bonfiglio, Alexandr Makarov, Thomas Colby, Paola Vagnarelli, Eric C Schirmer, Ivan Matic, William C Earnshaw
How eukaryotic chromosomes are compacted during mitosis has been a leading question in cell biology since the nineteenth century. Non-histone proteins such as condensin complexes contribute to chromosome shaping, but appear not to be necessary for mitotic chromatin compaction. Histone modifications are known to affect chromatin structure. As histones undergo major changes in their post-translational modifications during mitotic entry, we speculated that the spectrum of cell-cycle-specific histone modifications might contribute to chromosome compaction during mitosis...
September 2017: Open Biology
https://www.readbyqxmd.com/read/28899358/visualization-of-chromosome-condensation-in-plants-with-large-chromosomes
#3
Maria A Kuznetsova, Inna A Chaban, Eugene V Sheval
BACKGROUND: Most data concerning chromosome organization have been acquired from studies of a small number of model organisms, the majority of which are mammals. In plants with large genomes, the chromosomes are significantly larger than the animal chromosomes that have been studied to date, and it is possible that chromosome condensation in such plants was modified during evolution. Here, we analyzed chromosome condensation and decondensation processes in order to find structural mechanisms that allowed for an increase in chromosome size...
September 12, 2017: BMC Plant Biology
https://www.readbyqxmd.com/read/28882993/the-condensin-complex-is-a-mechanochemical-motor-that-translocates-along-dna
#4
Tsuyoshi Terakawa, Shveta Bisht, Jorine M Eeftens, Cees Dekker, Christian H Haering, Eric C Greene
Condensin plays crucial roles in chromosome organization and compaction, but the mechanistic basis for its functions remains obscure. Here, we use single-molecule imaging to demonstrate that Saccharomyces cerevisiae condensin is a molecular motor capable of ATP hydrolysis-dependent translocation along double-stranded DNA. Condensin's translocation activity is rapid and highly processive, with individual complexes traveling an average distance of ≥10 kilobases at a velocity of ~60 base pairs per second. Our results suggest that condensin may take steps comparable in length to its ~50-nanometer coiled-coil subunits, suggestive of a translocation mechanism that is distinct from any reported DNA motor protein...
September 7, 2017: Science
https://www.readbyqxmd.com/read/28882854/mutation-of-arabidopsis-smc4-identifies-condensin-as-a-corepressor-of-pericentromeric-transposons-and-conditionally-expressed-genes
#5
Jing Wang, Todd Blevins, Ram Podicheti, Jeremy R Haag, Ek Han Tan, Feng Wang, Craig S Pikaard
In eukaryotes, transcriptionally inactive loci are enriched within highly condensed heterochromatin. In plants, as in mammals, the DNA of heterochromatin is densely methylated and wrapped by histones displaying a characteristic subset of post-translational modifications. Growing evidence indicates that these chromatin modifications are not sufficient for silencing. Instead, they are prerequisites for further assembly of higher-order chromatin structures that are refractory to transcription but not fully understood...
September 7, 2017: Genes & Development
https://www.readbyqxmd.com/read/28862742/transcription-factor-retention-on-mitotic-chromosomes-regulatory-mechanisms-and-impact-on-cell-fate-decisions
#6
REVIEW
Mahé Raccaud, David M Suter
During mitosis, gene transcription stops, and the bulk of DNA-binding proteins are excluded from condensed chromosomes. While most gene-specific transcription factors are largely evicted from mitotic chromosomes, a subset remains bound to specific and non-specific DNA sites. Here, we review the current knowledge on the mechanisms leading to the retention of a subset of transcription factors on mitotic chromosomes, and discuss the implications in gene expression regulation and their potential as an epigenetic mechanism controlling stem cell self-renewal and differentiation...
September 1, 2017: FEBS Letters
https://www.readbyqxmd.com/read/28856628/primary-colonic-well-differentiated%C3%A2-%C3%A2-dedifferentiated-liposarcoma-of-the-ascending-colon-a-case-report
#7
Hiroshi Sawayama, Naoya Yoshida, Yuji Miyamoto, Tomoyuki Uchihara, Tasuku Toihata, Taisuke Yagi, Yukiharu Hiyoshi, Masaaki Iwatsuki, Yoshifumi Baba, Hideo Baba
BACKGROUND: Primary colonic and dedifferentiated liposarcomas are both remarkably rare. This work describes a case of primary colonic well-differentiated/dedifferentiated liposarcoma and reviews the clinical characteristics and current therapies for liposarcoma tumors. CASE PRESENTATION: A 52-year-old woman was referred to our hospital with a submucosal tumor of the ascending colon. Clinical analysis by ultrasound colonoscopy and computed tomography revealed a partially ossified tumor with irregular edges continuous with the muscular layer...
August 30, 2017: Surgical Case Reports
https://www.readbyqxmd.com/read/28854212/condensation-patterns-of-prophase-prometaphase-chromosome-are-correlated-with-h4k5-histone-acetylation-and-genomic-dna-contents-in-plants
#8
Lidiane Feitoza, Lucas Costa, Marcelo Guerra
Mitotic prophase chromosome condensation plays an essential role in nuclear division being therefore regulated by highly conserved mechanisms. However, degrees of chromatin condensation in prophase-prometaphase cells may vary along the chromosomes resulting in specific condensation patterns. We examined different condensation patterns (CPs) of prophase and prometaphase chromosomes and investigated their relationship with genome size and distribution of histone H4 acetylated at lysine 5 (H4K5ac) in 17 plant species...
2017: PloS One
https://www.readbyqxmd.com/read/28852823/a-proteomic-portrait-of-dinoflagellate-chromatin-reveals-abundant-rna-binding-proteins
#9
Mathieu Beauchemin, David Morse
Dinoflagellate chromatin is unique among eukaryotes, as the chromosomes are permanently condensed in a liquid crystal state instead of being packed in nucleosomes. However, how it is organized is still an unsolved mystery, in part due to the lack of a comprehensive catalog of dinoflagellate nuclear proteins. Here, we report the results of CHromatin Enrichment for Proteomics (CHEP) followed by shotgun mass spectrometry sequencing of the chromatin-associated proteins from the dinoflagellate Lingulodinum polyedra...
August 29, 2017: Chromosoma
https://www.readbyqxmd.com/read/28842486/the-bacterial-condensin-mukb-compacts-dna-by-sequestering-supercoils-and-stabilizing-topologically-isolated-loops
#10
Rupesh Kumar, Małgorzata Grosbart, Pearl Nurse, Soon Bahng, Claire L Wyman, Kenneth J Marians
MukB is a Structural Maintenance of Chromosome-like protein required for DNA condensation. The complete condensin is a large tripartite complex of MukB, the kleisin, MukF, and an accessory protein, MukE. As found previously, MukB DNA condensation is a stepwise process. We have defined these steps topologically: They proceed first via the formation of negative supercoils that are sequestered by the protein followed by hinge-hinge interactions between MukB dimers that stabilize topologically isolated loops in the DNA...
August 25, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28842485/the-mukb-topoisomerase-iv-interaction-is-required-for-proper-chromosome-compaction
#11
Rupesh Kumar, Pearl Nurse, Soon Bahng, Chong M Lee, Kenneth J Marians
The bacterial condensin MukB and the cellular decatenating enzyme Topoisomerase IV interact. This interaction stimulates intramolecular reactions catalyzed by Topoisomerase IV, supercoiled DNA relaxation and DNA knotting, but not intermolecular reactions such as decatenation of linked DNAs. In the accompanying article we demonstrated that MukB condenses DNA by sequestering negative supercoils and stabilizing topologically isolated loops in the DNA. We show here that the MukB-Topoisomerase IV interaction stabilizes MukB on DNA, increasing the extent of DNA condensation without increasing the amount of MukB bound to the DNA...
August 25, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28836096/dna-helix-the-importance-of-being-at-rich
#12
A E Vinogradov, O V Anatskaya
The AT-rich DNA is mostly associated with condensed chromatin, whereas the GC-rich sequence is preferably located in the dispersed chromatin. The AT-rich genes are prone to be tissue-specific (silenced in most tissues), while the GC-rich genes tend to be housekeeping (expressed in many tissues). This paper reports another important property of DNA base composition, which can affect repertoire of genes with high AT content. The GC-rich sequence is more liable to mutation. We found that Spearman correlation between human gene GC content and mutation probability is above 0...
August 23, 2017: Mammalian Genome: Official Journal of the International Mammalian Genome Society
https://www.readbyqxmd.com/read/28835378/density-imaging-of-heterochromatin-in-live-cells-using-orientation-independent-dic-microscopy
#13
Ryosuke Imai, Tadasu Nozaki, Tomomi Tani, Kazunari Kaizu, Kayo Hibino, Satoru Ide, Sachiko Tamura, Koichi Takahashi, Michael Shribak, Kazuhiro Maeshima
In eukaryotic cells, highly condensed inactive/silenced chromatin has long been called "heterochromatin." However, recent research suggests that such regions are in fact not fully transcriptionally silent, and that there exists only a moderate access barrier to heterochromatin. To further investigate this issue, it is critical to elucidate the physical properties of heterochromatin such as its total density in live cells. Here, using orientation-independent differential interference contrast (OI-DIC) microscopy, which is capable of mapping optical path differences, we investigated the density of the total materials in pericentric foci, a representative heterochromatin model, in live mouse NIH3T3 cells...
August 23, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28827720/label-free-in-vivo-raman-microspectroscopic-imaging-of-the-macromolecular-architecture-of-oocytes
#14
Philip Heraud, Katarzyna Maria Marzec, Qing-Hua Zhang, Wai Shan Yuen, John Carroll, Bayden R Wood
Confocal Raman spectroscopy (CRS) can provide information about oocyte competency through measurement of changes in the macromolecular architecture during oocyte development and maturation. Hitherto most spectroscopic studies have been limited to fixed oocytes due to the inherent difficulties working with live cells. Here we report the first three-dimensional images of living murine oocytes using CRS. We show that fixation induces significant changes in the macromolecular chemistry compared to living oocytes...
August 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28825727/condensin-mediated-remodeling-of-the-mitotic-chromatin-landscape-in-fission-yeast
#15
Yasutaka Kakui, Adam Rabinowitz, David J Barry, Frank Uhlmann
The eukaryotic genome consists of DNA molecules far longer than the cells that contain them. They reach their greatest compaction during chromosome condensation in mitosis. This process is aided by condensin, a structural maintenance of chromosomes (SMC) family member. The spatial organization of mitotic chromosomes and how condensin shapes chromatin architecture are not yet fully understood. Here we use chromosome conformation capture (Hi-C) to study mitotic chromosome condensation in the fission yeast Schizosaccharomyces pombe...
August 21, 2017: Nature Genetics
https://www.readbyqxmd.com/read/28812991/the-retinoblastoma-rb-tumor-suppressor-pushing-back-against-genome-instability-on-multiple-fronts
#16
REVIEW
Renier Vélez-Cruz, David G Johnson
The retinoblastoma (RB) tumor suppressor is known as a master regulator of the cell cycle. RB is mutated or functionally inactivated in the majority of human cancers. This transcriptional regulator exerts its function in cell cycle control through its interaction with the E2F family of transcription factors and with chromatin remodelers and modifiers that contribute to the repression of genes important for cell cycle progression. Over the years, studies have shown that RB participates in multiple processes in addition to cell cycle control...
August 16, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28800583/the-nucleoid-protein-dps-binds-genomic-dna-of-escherichia-coli-in-a-non-random-manner
#17
S S Antipov, M N Tutukina, E V Preobrazhenskaya, F A Kondrashov, M V Patrushev, S V Toshchakov, I Dominova, U S Shvyreva, V V Vrublevskaya, O S Morenkov, N A Sukharicheva, V V Panyukov, O N Ozoline
Dps is a multifunctional homododecameric protein that oxidizes Fe2+ ions accumulating them in the form of Fe2O3 within its protein cavity, interacts with DNA tightly condensing bacterial nucleoid upon starvation and performs some other functions. During the last two decades from discovery of this protein, its ferroxidase activity became rather well studied, but the mechanism of Dps interaction with DNA still remains enigmatic. The crucial role of lysine residues in the unstructured N-terminal tails led to the conventional point of view that Dps binds DNA without sequence or structural specificity...
2017: PloS One
https://www.readbyqxmd.com/read/28794351/unexpected-roles-of-a-shugoshin-protein-at-subtelomeres
#18
Junko Kanoh
A chromosome is composed of structurally and functionally distinct domains. Telomeres, which are located at the ends of linear chromosomes, play crucial roles in genome stability. Although substantial knowledge of telomeres has been accumulated, the regulation and function of subtelomeres, which are the domains adjacent to telomeres, remain largely unknown. In this review, I describe recent discoveries about the multiple roles of a shugoshin family protein, Sgo2, which is localized at centromeres in mitosis and contributes to precise chromosome segregation, in defining chromatin structure and functions of the subtelomeres in fission yeast...
August 9, 2017: Genes & Genetic Systems
https://www.readbyqxmd.com/read/28790150/phosphorylation-of-histone-h2a-at-serine-95-a-plant-specific-mark-involved-in-flowering-time-regulation-and-h2a-z-deposition
#19
Yanhua Su, Shiliang Wang, Fei Zhang, Han Zheng, Yana Liu, Tongtong Huang, Yong Ding
Phosphorylation of histone H3 affects transcription, chromatin condensation, and chromosome segregation. However, the role of phosphorylation of histone H2A remains unclear. Here, we found that Arabidopsis thaliana MUT9P-LIKE-KINASE (MLK4) phosphorylates histone H2A on serine 95, a plant-specific modification in the histone core domain. Mutations in MLK4 caused late flowering under long-day conditions but no notable phenotype under short days. MLK4 interacts with CIRCADIAN CLOCK ASSOCIATED1 (CCA1), which allows MLK4 to bind to the GIGANTEA (GI) promoter...
August 8, 2017: Plant Cell
https://www.readbyqxmd.com/read/28783137/acetylation-and-methylation-related-epigenetic-proteins-in-the-context-of-their-targets
#20
REVIEW
Nasir Javaid, Sangdun Choi
The nucleosome surface is covered with multiple modifications that are perpetuated by eight different classes of enzymes. These enzymes modify specific target sites both on DNA and histone proteins, and these modifications have been well identified and termed "epigenetics". These modifications play critical roles, either by affecting non-histone protein recruitment to chromatin or by disturbing chromatin contacts. Their presence dictates the condensed packaging of DNA and can coordinate the orderly recruitment of various enzyme complexes for DNA manipulation...
August 7, 2017: Genes
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