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chromosome condensation

Tsubasa Fuke, Takaaki Sato, Savyasachee Jha, Myra L Tansengco, Haruyuki Atomi
Phytoene (C40H64) is an isoprenoid and a precursor of various carotenoids which are of industrial value. Archaea can be considered to exhibit a relatively large capacity to produce isoprenoids, as they are components of their membrane lipids. Here, we aimed to produce isoprenoids such as phytoene in the hyperthermophilic archaeon Thermococcus kodakarensis. T. kodakarensis harbors a prenyltransferase gene involved in the biosynthesis of farnesyl pyrophosphate and geranylgeranyl pyrophosphate, which are precursors of squalene and phytoene, respectively...
January 16, 2018: Extremophiles: Life Under Extreme Conditions
Mariana Diaz, Ales Pecinka
Chromosome organization, dynamics and stability are required for successful passage through cellular generations and transmission of genetic information to offspring. The key components involved are Structural maintenance of chromosomes (SMC) complexes. Cohesin complex ensures proper chromatid alignment, condensin complex chromosome condensation and the SMC5/6 complex is specialized in the maintenance of genome stability. Here we summarize recent knowledge on the composition and molecular functions of SMC5/6 complex...
January 12, 2018: Genes
Xiaoming Sun, Paul D Kaufman
Ki-67 protein has been widely used as a proliferation marker for human tumor cells for decades. In recent studies, multiple molecular functions of this large protein have become better understood. Ki-67 has roles in both interphase and mitotic cells, and its cellular distribution dramatically changes during cell cycle progression. These localizations correlate with distinct functions. For example, during interphase, Ki-67 is required for normal cellular distribution of heterochromatin antigens and for the nucleolar association of heterochromatin...
January 10, 2018: Chromosoma
Nan Wu, Dong Ren, Su Li, Wenli Ma, Shaoyan Hu, Yan Jin, Sheng Xiao
BACKGROUND: Small GTP binding protein Rac1 is a component of NADPH oxidases and is essential for superoxide-induced cell death. Rac1 is activated by guanine nucleotide exchange factors (GEFs), and this activation can be blocked by regulator of chromosome condensation 2 (RCC2), which binds the switch regions of Rac1 to prevent access from GEFs. METHODS: Three cancer cell lines with up- or down-regulation of RCC2 were used to evaluate cell proliferation, apoptosis, Rac1 signaling and sensitivity to a group of nine chemotherapeutic drugs...
January 10, 2018: BMC Cancer
Emily J Platt, Leslie Smith, Mathew J Thayer
Mammalian cells replicate their chromosomes via a temporal replication program. The ASAR6 and ASAR15 genes were identified as loci that when disrupted result in delayed replication and condensation of entire human chromosomes. ASAR6 and ASAR15 are monoallelically expressed long noncoding RNAs that remain associated with the chromosome from which they are transcribed. The chromosome-wide effects of ASAR6 map to the antisense strand of an L1 retrotransposon within ASAR6 RNA, deletion or inversion of which delayed replication of human chromosome 6...
December 29, 2017: Journal of Cell Biology
Paulo Michel Pinheiro Ferreira, Kátia da Conceição Machado, Lívia Queiroz de Sousa, Daisy Jereissati Barbosa Lima, Bruno Marques Soares, Bruno Coêlho Cavalcanti, Sarah Sant' Anna Maranhão, Janaina da Costa de Noronha, Domingos de Jesus Rodrigues, Gardenia Carmen Gadelha Militão, Mariana Helena Chaves, Gerardo Magela Vieira-Júnior, Cláudia Pessoa, Manoel Odorico de Moraes, João Marcelo de Castro E Sousa, Ana Amélia de Carvalho Melo-Cavalcante
Skin toad secretion present physiologically active molecules to protect them against microorganisms, predators and infections. This work detailed the antiproliferative action of marinobufagin on tumor and normal lines, investigate its mechanism on HL-60 leukemia cells and its toxic effects on Allium cepa meristematic cells. Initially, cytotoxic action was assessed by colorimetric assays. Next, HL-60 cells were analyzed by morphological and flow cytometry techniques and growing A. cepa roots were examined after 72 h exposure...
December 26, 2017: Toxicology Letters
Hui Fan, Pin Lv, Xiangru Huo, Jicheng Wu, Qianfeng Wang, Lu Cheng, Yun Liu, Qiqun Tang, Ling Zhang, Feng Zhang, Xiaoqi Zheng, Hao Wu, Bo Wen
The eukaryotic chromosomes are folded into higher-order conformation to coordinate genome functions. Besides long-range chromatin loops, recent chromosome conformation capture (3C)-based studies indicated the higher level of chromatin structures including compartments and topologically associating domains (TADs), which may serve as units of genome organization and functions. However, the molecular machinery underlying these hierarchically three-dimensional (3D) chromatin architectures remains poorly understood...
December 22, 2017: Genome Research
Firdos Fatma, Sonam Verma, Aisha Kamal, Alka Srivastava
The present experiment was designed to monitor the morphotoxic, cytotoxic and genotoxic potential of Mancozeb (fungicide) in non-target plants using bulbs of Allium cepa. Mancozeb is classified as a contact fungicide and is registered for use on a variety of crop plants. In the present monitoring, Allium cepa bulbs were exposed to different concentrations of mancozeb viz., 10, 30, 50, 70, 90, 110, 130 and 150 ppm for 24 and 48 h. The potential morphotoxic and cytotoxic effects of mancozeb were examined by determining the average root number, average root length, mitotic index, relative abnormality rate (%) and frequency of abnormalities (%)...
December 19, 2017: Chemosphere
Gemma Lm Fisher, César L Pastrana, Victoria A Higman, Alan Koh, James A Taylor, Annika Butterer, Timothy Craggs, Frank Sobott, Heath Murray, Matthew P Crump, Fernando Moreno-Herrero, Mark S Dillingham
The ParB protein forms DNA bridging interactions around parS to condense DNA and earmark the bacterial chromosome for segregation. The molecular mechanism underlying the formation of these ParB networks is unclear. We show here that while the central DNA binding domain is essential for anchoring at parS, this interaction is not required for DNA condensation. Structural analysis of the C-terminal domain reveals a dimer with a lysine-rich surface that binds DNA non-specifically and is essential for DNA condensation in vitro...
December 15, 2017: ELife
Rachel Howard-Till, Josef Loidl
Condensin is a protein complex with diverse functions in chromatin packaging and chromosome condensation and segregation. We studied condensin in the evolutionarily distant protist model Tetrahymena, which features non-canonical nuclear organization and divisions. In Tetrahymena, the germline and soma are partitioned into two different nuclei within a single cell. Consistent with their functional specializations in sexual reproduction and gene expression, condensins of the germline nucleus and the polyploid somatic nucleus are composed of different subunits...
December 13, 2017: Molecular Biology of the Cell
Antônio P R Filho, Maruhen A D Silveira, Camila B do Nascimento, Luciana P G d'Arce
Gas station attendants are potentially exposed to carcinogenic substances. This study aimed to evaluate chronic occupational exposed gas station attendant's according to genetic parameters and its relationship with cancer predisposition. Forty gas station attendants were recruited and paired with 40 control subjects. Thousand cells from each subject were analyzed counting the number of pyknotic (PYC), karyolitic (KYL), karyorrhetic (KHC), condensed chromatin (CC), binucleated (BN), basal cells (BC), Nuclear buds (Nbud), and differentiated cells (DIFF)...
December 12, 2017: International Journal of Environmental Health Research
Gordana Wutz, Csilla Várnai, Kota Nagasaka, David A Cisneros, Roman R Stocsits, Wen Tang, Stefan Schoenfelder, Gregor Jessberger, Matthias Muhar, M Julius Hossain, Nike Walther, Birgit Koch, Moritz Kueblbeck, Jan Ellenberg, Johannes Zuber, Peter Fraser, Jan-Michael Peters
Mammalian genomes are spatially organized into compartments, topologically associating domains (TADs), and loops to facilitate gene regulation and other chromosomal functions. How compartments, TADs, and loops are generated is unknown. It has been proposed that cohesin forms TADs and loops by extruding chromatin loops until it encounters CTCF, but direct evidence for this hypothesis is missing. Here, we show that cohesin suppresses compartments but is required for TADs and loops, that CTCF defines their boundaries, and that the cohesin unloading factor WAPL and its PDS5 binding partners control the length of loops...
December 7, 2017: EMBO Journal
Johanna Gassler, Hugo B Brandão, Maxim Imakaev, Ilya M Flyamer, Sabrina Ladstätter, Wendy A Bickmore, Jan-Michael Peters, Leonid A Mirny, Kikuë Tachibana
Fertilization triggers assembly of higher-order chromatin structure from a condensed maternal and a naïve paternal genome to generate a totipotent embryo. Chromatin loops and domains have been detected in mouse zygotes by single-nucleus Hi-C (snHi-C), but not bulk Hi-C. It is therefore unclear when and how embryonic chromatin conformations are assembled. Here, we investigated whether a mechanism of cohesin-dependent loop extrusion generates higher-order chromatin structures within the one-cell embryo. Using snHi-C of mouse knockout embryos, we demonstrate that the zygotic genome folds into loops and domains that critically depend on Scc1-cohesin and that are regulated in size and linear density by Wapl...
December 7, 2017: EMBO Journal
Scott F Rusin, Mark E Adamo, Arminja N Kettenbach
Protein phosphorylation is a crucial regulatory mechanism that controls many aspects of cellular signaling. Casein kinase 2 (CK2), a constitutively expressed and active kinase, plays key roles in an array of cellular events including transcription and translation, ribosome biogenesis, cell cycle progression, and apoptosis. CK2 is implicated in cancerous transformation and is a therapeutic target in anti-cancer therapy. The specific and selective CK2 ATP competitive inhibitor, CX-4945 (silmitaseratib), is currently in phase 2 clinical trials...
2017: Frontiers in Cell and Developmental Biology
Sergey Mursalimov, Elena Deineko
The migration of nuclei between plant cells (cytomixis) is a mysterious cellular phenomenon frequently observable in the male meiosis of higher plants. Cytomixis attracts attention because of unknown cellular mechanisms underlying migration of nuclei and its potential evolutionary significance, since the genetic material is transferred between the cells that form pollen. Although cytomixis was discovered over a century ago, the advance in our understanding of this process has been rather insignificant because of methodological difficulties...
December 1, 2017: Protoplasma
Pavel Tchelidze, Aassif Benassarou, Hervé Kaplan, Marie-Françoise O'Donohue, Laurent Lucas, Christine Terryn, Levan Rusishvili, Giorgi Mosidze, Nathalie Lalun, Dominique Ploton
The nucleolus produces the large polycistronic transcript (47S precursor) containing the 18S, 5.8S and 28S rRNA sequences and hosts most of the nuclear steps of pre-rRNA processing. Among numerous components it contains condensed chromatin and active rRNA genes which adopt a more accessible conformation. For this reason, it is a paradigm of chromosome territory organization. Active rRNA genes are clustered within several fibrillar centers (FCs), in which they are maintained in an open configuration by Upstream Binding Factor (UBF) molecules...
2017: PloS One
Brett Robison, Vincent Guacci, Douglas Koshland
Cohesin is a conserved protein complex required for sister chromatid cohesion, chromosome condensation, DNA damage repair, and regulation of transcription. Although cohesin functions to tether DNA duplexes, the contribution of its individual domains to this activity remains poorly understood. We interrogated the Smc3p subunit of cohesin by random insertion mutagenesis. Analysis of a mutant in the Smc3p hinge revealed an unexpected role for this domain in cohesion maintenance and condensation. Further investigation revealed that the Smc3p hinge functions at a step following cohesin's stable binding to chromosomes and independently of Smc3p's regulation by the Eco1p acetyltransferase...
November 29, 2017: Molecular Biology of the Cell
Donglai Shen, Robert V Skibbens
Chl1 DNA helicase promotes sister chromatid cohesion and associates with both the cohesion establishment acetyltransferase Eco1/Ctf7 and the DNA polymerase processivity factor PCNA that supports Eco1/Ctf7 function. Mutation in CHL1 results in precocious sister chromatid separation and cell aneuploidy, defects that arise through reduced levels of chromatin-bound cohesins which normally tether together sister chromatids (trans tethering). Mutation of Chl1 family members (BACH1/BRIP/FANCJ and DDX11/ChlR1) also exhibit genotoxic sensitivities, consistent with a role for Chl1 in trans tethering which is required for efficient DNA repair...
2017: PloS One
Jamie Culkin, Lennart de Bruin, Marco Tompitak, Rob Phillips, Helmut Schiessel
Roughly 3/4 of human genomes are sequestered by nucleosomes, DNA spools with a protein core, dictating a broad range of biological processes, ranging from gene regulation, recombination, and replication, to chromosome condensation. Nucleosomes are dynamical structures and temporarily expose wrapped DNA through spontaneous unspooling from either end, a process called site exposure or nucleosome breathing. Here we ask how this process is influenced by the mechanical properties of the wrapped DNA, which is known to depend on the underlying base pair sequence...
November 30, 2017: European Physical Journal. E, Soft Matter
Katherine Furniss, Amit C J Vas, Andrew B Lane, Duncan J Clarke
Topoisomerase II activity is crucial to maintain genome stability through the removal of catenanes in the DNA formed during DNA replication and scaffolding the mitotic chromosome. Perturbed Topo II activity causes defects in chromosome segregation due to persistent catenations and aberrant DNA condensation during mitosis. Recently, novel top2 alleles in the yeast Saccharomyces cerevisiae revealed a checkpoint control which responds to perturbed Topo II activity. Described in this chapter are protocols for assaying the phenotypes seen in top2 mutants on a cell biological basis in live cells: activation of the Topo II checkpoint using spindle morphology, chromosome condensation using fluorescently labeled chromosomal loci and cell cycle progression by flow cytometry...
2018: Methods in Molecular Biology
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