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A Processive Arabidopsis Formin Modulates Actin Filament Dynamics in Association with Profilin

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Molecular Plant 2016年第6期9卷 900-910页

作者： Sha Zhang Chang Liu jiaojiao Wang Zhanhong Ren christopher j. Staiger Haiyun Ren Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education College of Life Science Beijing Normal University Beijing 100875 People'sRepublic of China Department of Biological Sciences Purdue University Hansen Life Sciences Research Building West Lafayette IN 47907-2064 USA

Formins are conserved regulators of actin cytoskeletal organization and dynamics that have been impli- cated to be important for cell division and cell polarity. The mechanism by which diverse formins regulate actin dynamics in plants is still not well understood. Using in vitro single-molecule imaging technology, we directly observed that the FH1-FH2 domain of an Arabidopsis thaliana formin, AtFH14, processively at- taches to the barbed end of actin filaments as a dimer and slows their elongation rate by 90%. The attach- ment persistence of FH1-FH2 is concentration dependent. Furthermore, by use of the triple-color total internal reflection fluorescence microscopy, we found that ABP29, a barbed-end capping protein, com- petes with FH1-FH2 at the filament barbed end, where its binding is mutually exclusive with AtFH14. In the presence of different plant profilin isoforms, FH1-FH2 enhances filament elongation rates from about 10 to 42 times. Filaments buckle when FH1-FH2 is anchored specifically to cover slides, further indicating that AtFH 14 moves processively on the elongating barbed end. At high concentration, AtFH 14 bundles actin filaments randomly into antiparallel or parallel spindle-like structures; however, the FH1-FH2-mediated bundles become thinner and longer in the presence of plant profilins. This is the direct demonstration of a processive formin from plants. Our results also illuminate the molecular mechanism of AtFH14 in regulating actin dynamics via association with profilin.

关键词： processive formin profilin capping protein actin bundle TIRF microscopy single molecule

Progress and Challenges for Live-cell Imaging of Genomic Loci Using CRISPR-based Platforms

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Genomics, Proteomics & Bioinformatics 2019年第2期17卷 119-128页

作者： Xiaotian Wu Shiqi Mao Yachen Ying christopher j.Krueger Antony K. Chen Department of Biomedical Engineering College of Engineering Peking University Beijing 100871 China School of Life Sciences Peking University Beijing 100871 China Wallace H Coulter Department of Biomedical Engineering Georgia Institute of Technology Atlanta GA 30332 USA

Chromatin conformation,localization,and dynamics are crucial regulators of cellular behaviors. Although fluorescence in situ hybridization-based techniques have been widely utilized for investigating chromatin architectures in healthy and diseased states,the requirement for cell fix-ation precludes the comprehensive dynamic analysis necessary to fully understand chromatin activ-ities. This has spurred the development and application of a variety of imaging methodologies for visualizing single chromosomal loci in the native cellular context. In this review,we describe currently-available approaches for imaging single genomic loci in cells,with special focus on clus-tered regularly interspaced short palindromic repeats (CRISPR)-based imaging approaches. In addition,we discuss some of the challenges that limit the application of CRISPR-based genomic imaging approaches,and potential solutions to address these challenges. We anticipate that,with continued refinement of CRISPR-based imaging techniques,significant understanding can be gained to help decipher chromatin activities and their relevance to cellular physiology and pathogenesis.

关键词： CRISPR Cas9 dCas9 Genomic imaging sgRNA

Deletion or underexpression of the Y-chromosome genes CDY2 and HSFY is associated with maturation arrest in American men with nonobstructive azoospermia

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Asian journal of Andrology 2012年第5期14卷 676-682页

作者： Peter j Stahl Anna N Mielnik christopher E Barbieri Peter N Schlegel Darius A Paduch Department of Urology Weill Cornell Medical CollegeNew York Presbyterian HospitaI-CornellNew YorkNY 10065USA

Maturation arrest （MA） refers to failure of germ cell development leading to clinical nonobstructive azoospermia. Although the azoospermic factor （AZF） region of the human Y chromosome is clearly implicated in some cases, thus far very little is known about which individual Y-chromosome genes are important for complete male germ cell development. We sought to identify single genes on the Y chromosome that may be implicated in the pathogenesis of nonobstructive azoospermia associated with MA in the American population. Genotype-phenotype analysis of 132 men with Y-chromosome microdeletions was performed. Protein-coding genes associated with MA were identified by visual analysis of a genotype-phenotype map. Genes associated with MA were selected as those genes within a segment of the Y chromosome that, when completely or partially deleted, were always associated with MA and absence of retrievable testicular sperm. Expression of each identified gene transcript was then measured with quantitative RT-PCR in testicular tissue from separate cohorts of patients with idiopathic MA and obstructive azoospermia. Ten candidate genes for association with MA were identified within an 8.4-Mb segment of the Y chromosome overlapping the AZFb region. CDY2and HSFYwere the only identified genes for which differences in expression were observed between the MA and obstructive azoospermia cohorts. Men with obstructive azoospermia had 12-fold higher relative expression of CDY2transcript （1.33__.0.40 vs. 0.11＋_0.04; P=O.O003） and 16-fold higher expression of HSFYtranscript （0.78__.0.32 vs. 0.05_0.02; P=O.O005） compared to men with MA. CDY2 and HSFYwere also underexpressed in patients with Sertoli cell only syndrome. These data indicate that CDY2and HSFYare located within a segment of the Y chromosome that is important for sperm maturation, and are underexpressed in testicular tissue derived from men with MA. These observations suggest that impairments in CDY2 or HSFYexpression could be impli

关键词： CDY1 protein CDY2 protein genetics histology HSFY human make infertility nonobstructive azoospermia spermato-genesis sperm maturation

Zirconium Doped Hydrotalcite-based NiAl Mixed Oxides——Enhanced Performance for Adsorption of SO2 and NO

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Chemical Research in Chinese Universities 2019年第3期35卷 490-497页

作者： ZHAO Ling ZHANG Yu LI Lexin XING Yating WANG Shuai christopher j. MARTYNIUK School cf Ecology and Environment Inner Mongolia University Huhhot 010021P.R.China College of Veterinary Medicine University of FloridaGainesvilleFL 32611USA

In the present study, the adsorptive behavior of zirconium doped hydrotalcite-based NiAl mixed oxides for reducing NO and SO2 was compared. According to tlie experimental results, the Zr^4+ cations were partially dissolved in crystalline NiO phase. With the addition of Zr, new centers for oxygen release and storage were formed, Lewis acid strength increased, and weakly and strongly alkaline sites were expanded. Moreover, in situ FTIR(Fourier transfonn infrared spectroscopy) investigation demonstrated that the amounts of surface bisulfite, sulfite, nitrite and nitrate spe? cies ofZrNiAlO were much more than those ofNiAlO. On the whole, this study concluded that the addition of Zr^4+ to NiAlO works to improve this compound as major absorbent for SO2 and NO.

关键词： SO2 NO Adsorption ZrNiAlO mixed oxide

A critical examination of compound stability predictions from machine-learned formation energies

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npj Computational Materials 2020年第1期6卷 858-868页

作者： christopher j.Bartel Amalie Trewartha Qi Wang Alexander Dunn Anubhav jain Gerbrand Ceder Department of Materials Science&Engineering University of CaliforniaBerkeleyBerkeleyCA 94720USA Energy Technologies Area Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA Materials Sciences Division Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA

Machine learning has emerged as a novel tool for the efficient prediction of material properties,and claims have been made that machine-learned models for the formation energy of compounds can approach the accuracy of Density Functional Theory(DFT).The models tested in this work include five recently published compositional models,a baseline model using stoichiometry alone,and a structural *** testing seven machine learning models for formation energy on stability predictions using the Materials Project database of DFT calculations for 85,014 unique chemical compositions,we show that while formation energies can indeed be predicted well,all compositional models perform poorly on predicting the stability of compounds,making them considerably less useful than DFT for the discovery and design of new *** critically,in sparse chemical spaces where few stoichiometries have stable compounds,only the structural model is capable of efficiently detecting which materials are *** nonincremental improvement of structural models compared with compositional models is noteworthy and encourages the use of structural models for materials discovery,with the constraint that for any new composition,the ground-state structure is not known a *** work demonstrates that accurate predictions of formation energy do not imply accurate predictions of stability,emphasizing the importance of assessing model performance on stability predictions,for which we provide a set of publicly available tests.

关键词： stability critical solids

Assessing risks from mining-induced ground movements near gas wells

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International journal of Mining Science and Technology 2020年第1期30卷 11-16页

作者： christopher Mark Gregory M.Rumbaugh Mine Safety and Health Administration PittsburghPAUSA

The proliferation of unconventional gas well development in the Northern Appalachian coalfields has raised a number of mine safety *** wells,which extract gas from deep shale formations,are characterized by gas volumes and pressures that are significantly higher than those observed at many conventional *** gas is composed largely of methane as well as other *** of planned and actively producing wells penetrate protective coal pillars or barriers within active mine boundaries,including chain pillars located between longwall *** released from a well damaged by mining-induced ground movements could pose a risk to miners by flowing into the mine *** mining-induced ground movements that may cause well damage include conventional subsidence,non-conventional subsidence(*** plane slip),pillar failure,and floor *** paper describes the known risk factors for each of the four failure *** includes a framework that can guide the risk assessment process when mining takes place near gas or oil wells.

关键词： Gas well Subsidence Coal protection pillar Risk matrix Longwall mining

Cooperation in an asymmetric volunteer's dilemma game with relatedness

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Chinese Science Bulletin 2012年第16期57卷 1972-1981页

作者： HE junZhou WANG RuiWu christopher X j jensen LI YaoTang LI ChaoQian School of Mathematics and Statistics Yunnan UniversityKunming 650091China State Key Laboratory of Genetic Resources and Evolution Kunming Institute of ZoologyChinese Academy of SciencesKunming 650223China Department of Mathematics and Science School of Liberal Arts and SciencesPratt Institute200 Willoughby AvenueBrooklynNY 11205USA

What motivates some members of a social group to voluntarily incur costs in order to provide for the common good? This question lies at the heart of theoretical and empirical studies of cooperative behavior. This is also the question that underlies the classic volunteer's dilemma model, which has been previously explored in scenarios where group members are related or interact asym- metrically. Here we present a model that combines asymmetry and relatedness, showing that the probability of volunteerism in such systems depends closely on both the degree of asymmetry and level of relatedness between interacting individuals. As has been shown in previous volunteer's dilemma models, the payoff ratio and overall group size also influence the probability of volunteerism. The probability of volunteerism decreases with increasing group size or decreasing cost-to-benefit ratio of the coplayers; in the presence of asymmetrical interactions, subordinate players were more likely to offer public goods than the dominant player. More asymmetrical interactions decrease the probability of volunteerism of the dominant player; overall volunteerism increases with increasing relatedness.

关键词：不对称性志愿者关联性合作游戏相互作用社会团体关联程度

Liver Fibrosis Helps to Distinguish Autoimmune Hepatitis from DILI with Autoimmune Features: A Review of Twenty Cases

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journal of Clinical and Translational Hepatology 2019年第1期7卷 21-26页

作者： christopher A.Febres-Aldana Sarah Alghamdi Kritika Krishnamurthy Robert j.Poppiti Department of Pathology and Laboratory Medicine Mount Sinai Medical CenterMiami BeachFLUSA Herbert Wertheim College of Medicine Florida International UniversityMiamiFLUSA

Background and Aims:Drug-induced liver injury with autoimmune features(AI-DILI)mimics the clinical presentation,and laboratory and pathologic features of idiopathic autoimmune hepatitis(AIH).We aimed to identify histopathologic hallmarks to differentiate these ***:All liver biopsies archived for the past 10 years were reviewed retrospectively to identify cases of recently detected liver injury associated with predominantly lymphoplasmacytic interphase hepatitis,positive markers for liver autoimmunity,and negative tests for viral *** cases were divided into AIH(n=12)or AI-DILI(n=8)*** qualitative evaluation of necroinflammatory changes and liver fibrosis were performed according to the Scheuer scoring *** densities were determined using Imagej(V1.51t,National Institutes of Health,Bethesda,MD,USA).Fibrosis was assessed on Masson trichrome-stained slides,and collagen deposition was estimated following a protocol of color ***:Necroinflammatory changes as well as densities(portal and lobular)of neutrophils and eosinophils,intracellular cholestasis,and regenerative changes did not differ between the two groups(P≥0.05).Neutrophil densities but not eosinophils showed a positive correlation with the severity of hepatocellular damage(r=0.6and 0.58,*** aminotransferase,P<0.05).Ceroidladen macrophages but not histiocytic aggregates appeared to be more common in AI-DILI(P<0.05).AIH patients presented more often with evidence of chronic damage,including higher scores of fibrosis and collagen deposition,in comparison to AI-DILI(P<0.05).Conclusions:Although there is no histologic feature pathognomonic for AI-DILI or AIH,advanced stages of liver fibrosis can be used to support the diagnosis of AIH in some *** diagnosis of AI-DILI requires follow-up and demonstration of complete remission after drug withdrawal with no need for immunosuppression.

关键词： DILI Autoimmune hepatitis Liver fibrosis Digital pathology

Inflation Targeting and Inflation Persistence

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Economic and Political Studies 2015年第1期3卷 3-17页

作者： GEORGE j.BRATSIOTIS jAKOB MADSEN christopher MARTIN the School of Social Sciences University of Manchester the Department of Economics Monash University the Department of Economics University of Bath

This paper argues that the adoption of an inflation target reduces the persistence of *** develop the theoretical literature on inflation persistence by introducing a Taylor Rule for monetary policy into a model of persistence and showing that inflation targets reduce inflation *** investigate changes in the time series properties of inflation in seven countries that introduced inflation targets in the late 1980s or early *** find that the persistence of inflation is greatly reduced or eliminated following the introduction of inflation targets.

关键词： Taylor Rule inflation targeting Phillips Curve inf