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https://www.readbyqxmd.com/read/29668119/n-heterocyclic-carbene-analogues-of-thiele-and-chichibabin-hydrocarbons
#1
Dennis Rottschäfer, Nga Kim T Ho, Beate Neumann, Hans-Georg Stammler, Maurice van Gastel, Diego M Andrada, Rajendra S Ghadwal
Stable N-heterocyclic carbene analogues of Thiele and Chichibabin hydrocarbons, [(IPr)(C6 H4 )(IPr)] and [(IPr)(C6 H4 )2 (IPr)] (4 and 5, respectively; IPr=C{N(2,6-iPr2 C6 H3 )}2 CHCH), are reported. In a nickel-catalyzed double carbenylation of 1,4-Br2 C6 H4 and 4,4'-Br2 (C6 H4 )2 with IPr (1), [(IPr)(C6 H4 )(IPr)](Br)2 (2) and [(IPr)(C6 H4 )2 (IPr)](Br)2 (3) were generated, which respectively afforded 4 and 5 as crystalline solids upon reduction with KC8 . Experimental and computational studies support the semiquinoidal nature of 5 with a small singlet-triplet energy gap ΔES-T of 10...
April 18, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29667342/middle-down-characterization-of-the-cell-cycle-dependence-of-histone-h4-post-translational-modifications-and-proteoforms
#2
Tingting Jiang, Michael E Hoover, Matthew V Holt, Michael A Freitas, Alan G Marshall, Nicolas L Young
Post-translational modifications (PTMs) of histones are important epigenetic regulatory mechanisms that are often dysregulated in cancer. We employ middle-down proteomics to investigate the PTMs and proteoforms of histone H4 during cell cycle progression. We use pH gradient weak cation exchange-hydrophilic interaction liquid chromatography (WCX-HILIC) for on-line liquid chromatography-mass spectrometry analysis to separate and analyze the proteoforms of histone H4. This provides enhanced separation of proteoforms, including positional isomers, and simplifies downstream data analysis...
April 17, 2018: Proteomics
https://www.readbyqxmd.com/read/29667226/probing-long-range-spin-spin-coupling-constants-in-2-halo-substituted-cyclohexanones-and-cyclohexanethiones-the-role-of-solvent-and-stereoelectronic-effects
#3
Fátima M P de Rezende, Matheus P Freitas, Teodorico C Ramalho
Earlier studies with 2-bromocyclohexanone demonstrated a measurable long-range coupling constant (4 JH2,H6 ) for the equatorial conformer, while 4 JH2,H4 and 4 JH4,H6 were not observed; as a consequence, it is inferred that the carbonyl group plays an important role particularly due to hyperconjugative interactions σC2H2 →π*C=O and σC6H6 →π*C=O. In the present study, NBO analysis and coupling constant calculations were performed to cyclohexanone and cyclohexanethione alpha substituted with F, Cl and Br, aiming to evaluate the halogen effect and acceptor character of the π* orbital on the long-range coupling pathway...
April 17, 2018: Magnetic Resonance in Chemistry: MRC
https://www.readbyqxmd.com/read/29665845/deletion-of-hp1%C3%AE-in-cardiac-myocytes-affects-h4k20me3-levels-but-does-not-impact-cardiac-growth
#4
Kyohei Oyama, Danny El-Nachef, Chen Fang, Hidemi Kajimoto, Jeremy P Brown, Prim B Singh, W Robb MacLellan
BACKGROUND: Heterochromatin, which is formed when tri-methyl lysine 9 of histone H3 (H3K9me3) is bound by heterochromatin 1 proteins (HP1s), plays an important role in differentiation and senescence by silencing cell cycle genes. Cardiac myocytes (CMs) accumulate heterochromatin during differentiation and demethylation of H3K9me3 inhibits cell cycle gene silencing and cell cycle exit in CMs; however, it is unclear if this process is mediated by HP1s. In this study, we created a conditional CM-specific HP1 gamma (HP1γ) knockout (KO) mouse model and tested whether HP1γ is required for cell cycle gene silencing and cardiac growth...
April 17, 2018: Epigenetics & Chromatin
https://www.readbyqxmd.com/read/29664998/compatible-ecological-niche-signals-between-biological-and-archaeological-datasets-for-late-surviving-neandertals
#5
Rachael C Bible, A Townsend Peterson
OBJECTIVES: To assess ecological niche similarity for biological and archaeological samples representing late-surviving Neandertals in Europe to evaluate the validity of combining these two types of data in ecological niche modeling analyses. MATERIALS AND METHODS: Tests of niche conservatism were used to assess niche similarity and niche identity of samples of morphologically diagnostic Neandertal remains and Middle Paleolithic (MP) archaeological sites dating to the time period leading up to Neandertal extinction...
April 17, 2018: American Journal of Physical Anthropology
https://www.readbyqxmd.com/read/29661843/functional-analysis-of-hif1-histone-chaperone-in-saccharomyces-cerevisiae
#6
Nora S Dannah, Syed Nabeel-Shah, Christoph F Kurat, Sarah A Sabatinos, Jeffrey Fillingham
The Hif1 protein in the yeast Saccharomyces cerevisie is an evolutionarily conserved H3/H4-specific chaperone and a subunit of the nuclear Hat1 complex that catalyzes the acetylation of newly synthesized histone H4. Hif1, as well as its human homolog NASP, has been implicated in an array of chromatin-related processes including histone H3/H4 transport, chromatin assembly and DNA repair. In this study, we elucidate the functional aspects of Hif1. Initially we establish the wide distribution of Hif1 homologs with an evolutionarily conserved pattern of four tetratricopeptide repeats (TPR) motifs throughout the major fungal lineages and beyond...
April 16, 2018: G3: Genes—Genomes—Genetics
https://www.readbyqxmd.com/read/29659581/an-interplay-between-multiple-sirtuins-promotes-completion-of-dna-replication-in-cells-with-short-telomeres
#7
Antoine Simoneau, Étienne Ricard, Hugo Wurtele
The evolutionarily-conserved sirtuin family of histone deacetylases regulates a multitude of DNA-associated processes. A recent genome-wide screen conducted in the yeast Saccharomyces cerevisiae identified Yku70/80, which regulate nonhomologous end-joining (NHEJ) and telomere structure, as being essential for cell proliferation in the presence of the pan-sirtuin inhibitor nicotinamide (NAM). Here, we show that sirtuin-dependent deacetylation of both histone H3 lysine 56 and H4 lysine 16 promotes growth of yku70Δ and yku80Δ cells, and that the NAM sensitivity of these mutants is not caused by defects in double-strand break repair by NHEJ, but rather by their inability to maintain normal telomere length...
April 16, 2018: PLoS Genetics
https://www.readbyqxmd.com/read/29657341/coordination-polymers-based-on-the-neutral-ditopic-ligand-c-6-h-4-po-och-3-2-2-involving-some-f-block-elements
#8
Kristijan Krekić, Eireen Käkel, Dieter Klintuch, Dana Bloß, Rudolf Pietschnig
An improved synthesis using microwave heating affords (C6 H4 PO(OCH3 )2 )2 in excellent isolated yield (95 %). The ligand properties of this bisphosphonateester were explored towards hard metal centers M 2+ ( M = Ca, UO2 ) and M 3+ ( M = La, Ce, Sm, Eu) resulting in coordination polymers, for which the reduction of ionic size of the central metal atom resulted in lower-dimensional structural motifs as opposed to higher dimensional networks obtained for the larger ions. All coordination polymers were characterized by single-crystal X-ray diffraction, IR spectroscopy, and combustion analysis...
February 15, 2018: Zeitschrift Für Anorganische und Allgemeine Chemie
https://www.readbyqxmd.com/read/29655943/effects-of-a-histamine-h-4-receptor-antagonist-on-cisplatin-induced-anorexia-in-mice
#9
Kouichi Yamamoto, Rikuya Okui, Atsushi Yamatodani
Cancer chemotherapy often induces gastrointestinal symptoms such as anorexia, nausea, and vomiting. Antiemetic agents are effective in inhibiting nausea and vomiting, but patients still experience anorexia. We previously reported that chemotherapeutic agent-induced anorexia is associated with an increase of inflammatory cytokines. Other studies also reported that antagonism of the histamine H4 receptor is anti-inflammatory. In this study, we investigated the involvement of the H4 receptor in the development of chemotherapy-induced anorexia in mice...
April 12, 2018: Neuroscience Letters
https://www.readbyqxmd.com/read/29655483/chromatin-fiber-folding-directed-by-cooperative-histone-tail-acetylation-and-linker-histone-binding
#10
Gavin D Bascom, Tamar Schlick
In eukaryotic chromatin, islands of histone tail acetylation are found near transcription start sites and enhancers, whereas linker histones (LHs) are localized in intergenic regions with wild-type (WT) histone tails. However, the structural mechanisms by which acetylation, in combination with LH binding, modulates chromatin compaction and hence transcription regulation are unknown. To explore the folding propensity by which these features may govern gene expression, we analyze 20 kb fibers that contain regularly spaced acetylation islands of two sizes (2 or 5 kb) with various LH levels by mesoscale modeling...
April 11, 2018: Biophysical Journal
https://www.readbyqxmd.com/read/29649476/h2a-z-containing-nucleosomes-are-evicted-to-activate-atmyb44-transcription-in-response-to-salt-stress
#11
Nguyen Hoai Nguyen, Jong-Joo Cheong
Transcripts of the Arabidopsis transcription factor gene, AtMYB44, accumulate rapidly to mediate a tolerance mechanism in response to salt stress. The AtMYB44 promoter is activated by salt stress, as illustrated in AtMYB44pro::GUS transgenic plants. Chromatin immunoprecipitation (ChIP) assays revealed that RNA polymerases were enriched on the AtMYB44 gene, especially on TSS-proximal regions, and nucleosome density was markedly reduced in the AtMYB44 gene-body region in response to salt stress. In addition, H2A...
April 9, 2018: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/29644260/biochemical-analysis-of-dimethyl-suberimidate-crosslinked-yeast-nucleosomes
#12
Yuichi Ichiakwa, Paul D Kaufman
Nucleosomes are the fundamental unit of eukaryotic chromosome packaging, comprised of 147 bp of DNA wrapped around two molecules of each of the core histone proteins H2A, H2B, H3, and H4. Nucleosomes are symmetrical, with one axis of symmetry centered on the homodimeric interaction between the C-termini of the H3 molecules. To explore the functional consequences of nucleosome symmetry, we designed an obligate pair of H3 heterodimers, termed H3X and H3Y, allowing us to compare cells with single or double H3 alterations...
March 20, 2018: Bio-protocol
https://www.readbyqxmd.com/read/29643506/structure-and-regulation-of-the-human-ino80-nucleosome-complex
#13
Rafael Ayala, Oliver Willhoft, Ricardo J Aramayo, Martin Wilkinson, Elizabeth A McCormack, Lorraine Ocloo, Dale B Wigley, Xiaodong Zhang
Access to DNA within nucleosomes is required for a variety of processes in cells including transcription, replication and repair. Consequently, cells encode multiple systems that remodel nucleosomes. These complexes can be simple, involving one or a few protein subunits, or more complicated multi-subunit machines 1 . Biochemical studies2-4 have placed the motor domains of several chromatin remodellers in the superhelical location 2 region of the nucleosome. Structural studies of yeast Chd1 and Snf2-a subunit in the complex with the capacity to remodel the structure of chromatin (RSC)-in complex with nucleosomes5-7 have provided insights into the basic mechanism of nucleosome sliding performed by these complexes...
April 11, 2018: Nature
https://www.readbyqxmd.com/read/29643389/histone-h3-3-sub-variant-h3mm7-is-required-for-normal-skeletal-muscle-regeneration
#14
Akihito Harada, Kazumitsu Maehara, Yusuke Ono, Hiroyuki Taguchi, Kiyoshi Yoshioka, Yasuo Kitajima, Yan Xie, Yuko Sato, Takeshi Iwasaki, Jumpei Nogami, Seiji Okada, Tetsuro Komatsu, Yuichiro Semba, Tatsuya Takemoto, Hiroshi Kimura, Hitoshi Kurumizaka, Yasuyuki Ohkawa
Regulation of gene expression requires selective incorporation of histone H3 variant H3.3 into chromatin. Histone H3.3 has several subsidiary variants but their functions are unclear. Here we characterize the function of histone H3.3 sub-variant, H3mm7, which is expressed in skeletal muscle satellite cells. H3mm7 knockout mice demonstrate an essential role of H3mm7 in skeletal muscle regeneration. Chromatin analysis reveals that H3mm7 facilitates transcription by forming an open chromatin structure around promoter regions including those of myogenic genes...
April 11, 2018: Nature Communications
https://www.readbyqxmd.com/read/29643253/in-vitro-in-vivo-extrapolation-of-oatp1b-mediated-drug-drug-interactions-in-cynomolgus-monkey
#15
Ayse Ufuk, Rachel E Kosa, Hongying Gao, Yi-An Bi, Sweta Modi, Dana Gates, A David Rodrigues, Larry M Tremaine, Manthena V S Varma, J Brian Houston, Aleksandra Galetin
Hepatic organic anion transporting polypeptides (OATP) 1B1 and 1B3 are clinically relevant transporters associated with significant drug-drug interactions (DDIs) and safety concerns. Given that OATP1Bs in cynomolgus monkey share >90% degree of gene and amino acid sequence identity with human orthologs, we evaluated the in vitro-in vivo translation of OATP1B-mediated DDI risk using this preclinical model. In vitro studies using cynomolgus monkey hepatocytes showed active uptake Km values of 2.0 and 3.9 µM for OATP1B probe substrates, pitavastatin and rosuvastatin, respectively...
April 11, 2018: Journal of Pharmacology and Experimental Therapeutics
https://www.readbyqxmd.com/read/29629154/models-for-aerobic-carbon-monoxide-dehydrogenase-synthesis-characterization-and-reactivity-of-paramagnetic-mo-v-o-%C3%AE-s-cu-i-complexes
#16
Craig Gourlay, David J Nielsen, David J Evans, Jonathan M White, Charles G Young
Reaction of [CoCp2 ][TpiPr MoOS(OAr)] [Cp = η5 -cyclopentadienyl; TpiPr = hydrotris(3-isopropylpyrazol-1-yl)borate; OAr = phenolate or derivative thereof] with [Cu(NCMe)(Me3 tcn)]BF4 (Me3 tcn = 1,4,7-trimethyl-1,4,7-triazacyclononane) in MeCN at -30 °C results in the formation of red-brown/black, paramagnetic, μ-sulfido-Mo(v)/Cu(i) complexes, TpiPr MoO(OAr)(μ-S)Cu(Me3 tcn). The complexes possess the MoO(μ-S)Cu core found in aerobic carbon monoxide dehydrogenases (CODHs) and exhibit X-band EPR spectra closely related to those of semi-reduced CODH, with g iso ∼ 1...
January 28, 2018: Chemical Science
https://www.readbyqxmd.com/read/29626919/the-4d-nucleome-genome-compartmentalization-in-an-evolutionary-context
#17
REVIEW
T Cremer, M Cremer, C Cremer
4D nucleome research aims to understand the impact of nuclear organization in space and time on nuclear functions, such as gene expression patterns, chromatin replication, and the maintenance of genome integrity. In this review we describe evidence that the origin of 4D genome compartmentalization can be traced back to the prokaryotic world. In cell nuclei of animals and plants chromosomes occupy distinct territories, built up from ~1 Mb chromatin domains, which in turn are composed of smaller chromatin subdomains and also form larger chromatin domain clusters...
April 2018: Biochemistry. Biokhimii︠a︡
https://www.readbyqxmd.com/read/29625896/co-inhibitory-molecule-b7-superfamily-member-1-expressed-by-tumor-infiltrating-myeloid-cells-induces-dysfunction-of-anti-tumor-cd8-t-cells
#18
Jing Li, Younghee Lee, Yanjian Li, Yu Jiang, Huiping Lu, Wenjuan Zang, Xiaohong Zhao, Liguo Liu, Yang Chen, Haidong Tan, Zhiying Yang, Michael Q Zhang, Tak W Mak, Ling Ni, Chen Dong
The molecular mechanisms whereby CD8+ T cells become "exhausted" in the tumor microenvironment remain unclear. Programmed death ligand-1 (PD-L1) is upregulated on tumor cells and PD-1-PD-L1 blockade has significant efficacy in human tumors; however, most patients do not respond, suggesting additional mechanisms underlying T cell exhaustion. B7 superfamily member 1 (B7S1), also called B7-H4, B7x, or VTCN1, negatively regulates T cell activation. Here we show increased B7S1 expression on myeloid cells from human hepatocellular carcinoma correlated with CD8+ T cell dysfunction...
March 29, 2018: Immunity
https://www.readbyqxmd.com/read/29624162/streptomyces-boninensis-sp-nov-isolated-from-soil-from-a-limestone-cave-in-the-ogasawara-islands
#19
Akira Také, Yuki Inahashi, Satoshi Ōmura, Yōko Takahashi, Atsuko Matsumoto
Actinomycete strain K11-0400T was isolated from a soil sample collected in the Ogasawara Islands (also known as the Bonin Islands), Tokyo, Japan. Mature spore chains of strain K11-0400T had more than 20 spores per chain. The strain contained ll-diaminopimelic acid as the diamino acid in whole-cell hydrolysates, and MK-9(H6) and MK-9(H4) were the predominant menaquinones. The polar lipids were phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylinositol, and no diagnostic whole-cell sugar was detected...
April 6, 2018: International Journal of Systematic and Evolutionary Microbiology
https://www.readbyqxmd.com/read/29623757/icariin-a-flavonoid-with-anti-cancer-effects-alleviated-paclitaxel-induced-neuropathic-pain-in-a-sirt1-dependent-manner
#20
Yulong Gui, Jie Zhang, Liang Chen, Shunyuan Duan, Jing Tang, Wei Xu, Aiyuan Li
Background One of the most common side effects of paclitaxel was dosage-dependently painful neuropathy. Various reports indicated that spinal neuroinflammation was involved in paclitaxel-induced neuropathic pain. This study investigated the effect of icariin on paclitaxel-induced neuroinflammation and peripheral neuropathy in rats. Methods Two parts were included in this study. In part one, the effect of icariin on paclitaxel-induced neuropathic pain was investigated. Mechanical thresholds were measured as primary outcomes...
January 2018: Molecular Pain
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