原特提斯的消減極性:西昆侖128公里巖體的啟示

The Yirba (128 km) pluton is an early Paleozoic dioritic intrusion of western Kunlun orogenic belt, northwest China as an important element when reconstructing the evolution history of this belt. Due to the scarcity of field data and methodological difference in studying this pluton, however, no consensus for its age, source and tectonic setting has been adopted. In this paper, we present new geochronological and geochemical data for the Yirba pluton, aiming to better understand its age, source, and hence the early Paleozoic tectonic evolutionary history of western Kunlun. U-Pb data by single grain zircon analyses suggest that the Yirba pluton was emplaced 471 ± 5 Ma ago and contains ca. 490 Ma zircon grains inherited from source, or captured in the magma chamber. The pluton is enriched in Al 2 O 3 (15.7% ∼ 18.4%), Sr (470 ∼ 864 μg/g) and other LILEs (large ion lithosphile elements), but relatively depleted in HFSE (high field strength elements and HREE), with LREE-enriched patterns and low to medium europium anomalies (δEu = ∼ 0.7), showing typical characteristics of I-type, volcanic arc granitoids. Although its relatively high Al 2 O 3, Sr and low MgO contents make it resemble adakite, its relatively high Yb (1.92 ∼ 2.88 μg/g), Y (19.4 ∼ 34.0 μg/g) contents, low Sr/Y (24.2 ∼ 37.0) , Zr/Sm (7.3 ∼ 21) and relatively high initial Sr isotope ratios (0.7075 ∼ 0.7091) do not support a subducting slab origin. Its Nd model ages (1.06 ∼ 1.35 Ga) indicate a juvenile source, while its O isotope compositions (+5.7‰ ∼ + 7.4‰) and Sr-O isotope relationship preclude significant involvement of sialic materials. The major, trace, REE and Nd-Sr-O isotope compositions strongly suggest that the Yirba pluton was formed by partial melting of mafic lower crust in a southward growing, active continental margin environment. The existence of volcanic arc granitoids in the south margin of the North Kunlun terrane suggests that the subduction polarity of the Proto-Tethys was northward.128公里巖體是西昆侖造山帶中一個早古生代的花崗閃長巖體,長期以來一直是研究西昆侖構造演化的重要參考依據。然而由于區域地質資料的不足和研究手段的不同,對該巖體的形成年代、源區性質以及構造背景等方面還存在著不同的認識。本文試圖通過地質年代學和地球化學方面的研究,明確128公里巖體的成巖時代和構造背景,進而制約西昆侖的早古生代構造演化。單顆粒鋯石的U-Pb定年結果表明128公里巖體形成于471±5 Ma并含有可能形成于早期巖漿房或繼承自源區的490 Ma左右的鋯石。128公里巖體富Al_2O_3(15.7％～18.4％),Sr(470～864μg/g)和大離子親石元素但相對虧損 高場強元素,相對富集輕稀土且具有低到中等的負銪異常(δEu=～0.7),顯示出典型的Ⅰ型弧花崗巖特征。盡管其富集Al_2O_3、Sr、相對低的MgO含量和Y/Yb比值使其非常類似于埃達克巖,但其相對高的Yb(1.92～2.88μg/g)、Y(19.4～34.0μg/g)含量,低的Sr/Y(24.2～37.0)和Zr/Sm(7.3～21)比值以及相對高的初始Sr同位素組成(0.7075～0.7091)排除了消減板塊在石榴石穩定區發生部分熔融的可能性。低的氧同位素组成( + 5.7％～7.4％) 以及Sr-O 同位素关系表明该岩体并非形成于地慢来源的岩泉与变质围岩间的同化混染。高的稀土含量、明显的稀土分馏以及相对高的Sr 同位素组成表明12 8 公里岩体不大可能形成于受陆源物质影响较小的大洋岛弧, 而更可能形成于活动大陆边缘环境中基性地壳物质的部分熔融。北昆仑地体的南缘存在火山弧型花岗岩的事实表明, 原特提斯的消减方向应当是向北的。published_or_final_versio

Mapping Dynamic Histone Acetylation Patterns to Gene Expression in Nanog-depleted Murine Embryonic Stem Cells

Embryonic stem cells (ESC) have the potential to self-renew indefinitely and to differentiate into any of the three germ layers. The molecular mechanisms for self-renewal, maintenance of pluripotency and lineage specification are poorly understood, but recent results point to a key role for epigenetic mechanisms. In this study, we focus on quantifying the impact of histone 3 acetylation (H3K9,14ac) on gene expression in murine embryonic stem cells. We analyze genome-wide histone acetylation patterns and gene expression profiles measured over the first five days of cell differentiation triggered by silencing Nanog, a key transcription factor in ESC regulation. We explore the temporal and spatial dynamics of histone acetylation data and its correlation with gene expression using supervised and unsupervised statistical models. On a genome-wide scale, changes in acetylation are significantly correlated to changes in mRNA expression and, surprisingly, this coherence increases over time. We quantify the predictive power of histone acetylation for gene expression changes in a balanced cross-validation procedure. In an in-depth study we focus on genes central to the regulatory network of Mouse ESC, including those identified in a recent genome-wide RNAi screen and in the PluriNet, a computationally derived stem cell signature. We find that compared to the rest of the genome, ESC-specific genes show significantly more acetylation signal and a much stronger decrease in acetylation over time, which is often not reflected in an concordant expression change. These results shed light on the complexity of the relationship between histone acetylation and gene expression and are a step forward to dissect the multilayer regulatory mechanisms that determine stem cell fate.Comment: accepted at PLoS Computational Biolog

Notch signaling during human T cell development

Notch signaling is critical during multiple stages of T cell development in both mouse and human. Evidence has emerged in recent years that this pathway might regulate T-lineage differentiation differently between both species. Here, we review our current understanding of how Notch signaling is activated and used during human T cell development. First, we set the stage by describing the developmental steps that make up human T cell development before describing the expression profiles of Notch receptors, ligands, and target genes during this process. To delineate stage-specific roles for Notch signaling during human T cell development, we subsequently try to interpret the functional Notch studies that have been performed in light of these expression profiles and compare this to its suggested role in the mouse

Clutch Frequency Affects the Offspring Size-Number Trade-Off in Lizards

Background: Studies of lizards have shown that offspring size cannot be altered by manipulating clutch size in species with a high clutch frequency. This raises a question of whether clutch frequency has a key role in influencing the offspring sizenumber trade-off in lizards. Methodology/Principal Findings: To test the hypothesis that females reproducing more frequently are less likely to tradeoff offspring size against offspring number, we applied the follicle ablation technique to female Eremias argus (Lacertidae) from Handan (HD) and Gonghe (GH), the two populations that differ in clutch frequency. Follicle ablation resulted in enlargement of egg size in GH females, but not in HD females. GH females switched from producing a larger number of smaller eggs in the first clutch to a smaller number of larger eggs in the second clutch; HD females showed a similar pattern of seasonal shifts in egg size, but kept clutch size constant between the first two clutches. Thus, the egg sizenumber trade-off was evident in GH females, but not in HD females. Conclusions/Significance: As HD females (mean = 3.1 clutches per year) reproduce more frequently than do GH females (mean = 1.6 clutches per year), our data therefore validate the hypothesis tested. Our data also provide an inference that maximization of maternal fitness could be achieved in females by diverting a large enough, rather than a higher-than-usual

Disparities and risks of sexually transmissible infections among men who have sex with men in China: a meta-analysis and data synthesis.

BACKGROUND: Sexually transmitted infections (STIs), including Hepatitis B and C virus, are emerging public health risks in China, especially among men who have sex with men (MSM). This study aims to assess the magnitude and risks of STIs among Chinese MSM. METHODS: Chinese and English peer-reviewed articles were searched in five electronic databases from January 2000 to February 2013. Pooled prevalence estimates for each STI infection were calculated using meta-analysis. Infection risks of STIs in MSM, HIV-positive MSM and male sex workers (MSW) were obtained. This review followed the PRISMA guidelines and was registered in PROSPERO. RESULTS: Eighty-eight articles (11 in English and 77 in Chinese) investigating 35,203 MSM in 28 provinces were included in this review. The prevalence levels of STIs among MSM were 6.3% (95% CI: 3.5-11.0%) for chlamydia, 1.5% (0.7-2.9%) for genital wart, 1.9% (1.3-2.7%) for gonorrhoea, 8.9% (7.8-10.2%) for hepatitis B (HBV), 1.2% (1.0-1.6%) for hepatitis C (HCV), 66.3% (57.4-74.1%) for human papillomavirus (HPV), 10.6% (6.2-17.6%) for herpes simplex virus (HSV-2) and 4.3% (3.2-5.8%) for Ureaplasma urealyticum. HIV-positive MSM have consistently higher odds of all these infections than the broader MSM population. As a subgroup of MSM, MSW were 2.5 (1.4-4.7), 5.7 (2.7-12.3), and 2.2 (1.4-3.7) times more likely to be infected with chlamydia, gonorrhoea and HCV than the broader MSM population, respectively. CONCLUSION: Prevalence levels of STIs among MSW were significantly higher than the broader MSM population. Co-infection of HIV and STIs were prevalent among Chinese MSM. Integration of HIV and STIs healthcare and surveillance systems is essential in providing effective HIV/STIs preventive measures and treatments. TRIAL REGISTRATION: PROSPERO NO: CRD42013003721

Regulation of Adipose Tissue Stromal Cells Behaviors by Endogenic Oct4 Expression Control

BACKGROUND: To clarify the role of the POU domain transcription factor Oct4 in Adipose Tissue Stromal Cells (ATSCs), we investigated the regulation of Oct4 expression and other embryonic genes in fully differentiated cells, in addition to identifying expression at the gene and protein levels. The ATSCs and several immature cells were routinely expressing Oct4 protein before and after differentiating into specific lineages. METHODOLOGY/PRINCIPAL FINDINGS AND CONCLUSIONS: Here, we demonstrated the role of Oct4 in ATSCs on cell proliferation and differentiation. Exogenous Oct4 improves adult ATSCs cell proliferation and differentiation potencies through epigenetic reprogramming of stemness genes such as Oct4, Nanog, Sox2, and Rex1. Oct4 directly or indirectly induces ATSCs reprogramming along with the activation of JAK/STAT3 and ERK1/2. Exogenic Oct4 introduced a transdifferentiation priority into the neural lineage than mesodermal lineage. Global gene expression analysis results showed that Oct4 regulated target genes which could be characterized as differentially regulated genes such as pluripotency markers NANOG, SOX2, and KLF4 and markers of undifferentiated stem cells FOXD1, CDC2, and EPHB1. The negatively regulated genes included FAS, TNFR, COL6A1, JAM2, FOXQ1, FOXO1, NESTIN, SMAD3, SLIT3, DKK1, WNT5A, BMP1, and GLIS3 which are implicated in differentiation processes as well as a number of novel genes. Finally we have demonstrated the therapeutic utility of Oct4/ATSCs were introduced into the mouse traumatic brain, engrafted cells was more effectively induces regeneration activity with high therapeutic modality than that of control ATSCs. Engrafted Oct4/ATSCs efficiently migrated and transdifferentiated into action potential carrying, functionally neurons in the hippocampus and promoting the amelioration of lesion cavities

Association between RUNX3 promoter methylation and gastric cancer: a meta-analysis

<p>Abstract</p> <p>Background</p> <p>Runt-related transcription factor 3 (RUNX3) is a member of the runt-domain family of transcription factors and has been reported to be a candidate tumor suppressor in gastric cancer. However, the association between RUNX3 promoter methylation and gastric cancer remains unclear.</p> <p>Methods</p> <p>We systematically reviewed studies of RUNX3 promoter methylation and gastric cancer published in English or Chinese from January 2000 to January 2011, and quantified the association between RUNX3 promoter methylation and gastric cancer using meta-analysis methods.</p> <p>Results</p> <p>A total of 1740 samples in 974 participants from seventeen studies were included in the meta-analysis. A significant association was observed between RUNX3 promoter methylation and gastric cancer, with an aggregated odds ratio (OR) of 5.63 (95%CI 3.15, 10.07). There was obvious heterogeneity among studies. Subgroup analyses (including by tissue origin, country and age), meta-regression were performed to determine the source of the heterogeneity. Meta-regression showed that the trend in ORs was inversely correlated with age. No publication bias was detected. The ORs for RUNX3 methylation in well-differentiated <it>vs </it>undifferentiated gastric cancers, and in intestinal-type <it>vs </it>diffuse-type carcinomas were 0.59 (95%CI: 0.30, 1.16) and 2.62 (95%CI: 1.33, 5.14), respectively. There were no significant differences in RUNX3 methylation in cancer tissues in relation to age, gender, TNM stage, invasion of tumors into blood vessel or lymphatic ducts, or tumor stage.</p> <p>Conclusions</p> <p>This meta-analysis identified a strong association between methylation of the RUNX3 promoter and gastric cancer, confirming the role of RUNX3 as a tumor suppressor gene.</p

Additive Protection by Antioxidant and Apoptosis-Inhibiting Effects on Mosquito Cells with Dengue 2 Virus Infection

Cytopathic effects (CPEs) in mosquito cells are generally trivial compared to those that occur in mammalian cells, which usually end up undergoing apoptosis during dengue virus (DENV) infection. However, oxidative stress was detected in both types of infected cells. Despite this, the survival of mosquito cells benefits from the upregulation of genes related to antioxidant defense, such as glutathione S transferase (GST). A second defense system, i.e., consisting of antiapoptotic effects, was also shown to play a role in protecting mosquito cells against DENV infection. This system is regulated by an inhibitor of apoptosis (IAP) that is an upstream regulator of caspases-9 and -3. DENV-infected C6/36 cells with double knockdown of GST and the IAP showed a synergistic effect on activation of these two caspases, causing a higher rate of apoptosis (>20%) than those with knockdown of each single gene (∼10%). It seems that the IAP acts as a second line of defense with an additional effect on the survival of mosquito cells with DENV infection. Compared to mammalian cells, residual hydrogen peroxide in DENV-infected C6/36 cells may signal for upregulation of the IAP. This novel finding sheds light on virus/cell interactions and their coevolution that may elucidate how mosquitoes can be a vector of DENV and probably most other arboviruses in nature

Regulated Fluctuations in Nanog Expression Mediate Cell Fate Decisions in Embryonic Stem Cells

The notion that the differentiated state of a cell population is determined simply by expression of specific marker genes is changing. In this work, the authors reveal that a pluripotent cell population comprises cells with temporal fluctuations in the expression of Nanog

Cancer Genes Hypermethylated in Human Embryonic Stem Cells

Developmental genes are silenced in embryonic stem cells by a bivalent histone-based chromatin mark. It has been proposed that this mark also confers a predisposition to aberrant DNA promoter hypermethylation of tumor suppressor genes (TSGs) in cancer. We report here that silencing of a significant proportion of these TSGs in human embryonic and adult stem cells is associated with promoter DNA hypermethylation. Our results indicate a role for DNA methylation in the control of gene expression in human stem cells and suggest that, for genes repressed by promoter hypermethylation in stem cells in vivo, the aberrant process in cancer could be understood as a defect in establishing an unmethylated promoter during differentiation, rather than as an anomalous process of de novo hypermethylation