Viscoelastic stress change from the 1931 M_(w)7.8 Fuyun earthquake and its impacts on seismic activity around the Altai mountains

The 1931 M_(w)7.8 Fuyun earthquake occurred around the Altai mountains, an intracontinental deformation belt with limited active strain-rate accumulation. To explore whether seismic activity in this deformation belt was affected by stress interaction among different active faults, we calculate the Coulomb failure stress change(ΔCFS) induced by the Fuyun earthquake due to coseismic deformation of the elastic crust and postseismic viscoelastic relaxation of the lower crust and upper mantle. Numerical results show that the total ΔCFS at a 10-km depth produced by the Fuyun earthquake attains approximately 0.015-0.134 bar near the epicenter, and just before the occurrence of the 2003 M_(w)7.2 Chuya earthquake, which distances about 400 km away from the Fuyun earthquake. Among the increased ΔCFS,viscoelastic relaxation from 1931 to 2003 contributes to approximately 0.014-0.131 bar, accounting for>90% of the total ΔCFS. More importantly, we find that for the recorded seismicity in the region with a radius of about 270 km to the Fuyun earthquake from 1970 to 2018, the percentage of earthquakes that fall in positive lobes of ΔCFS resolved on the NNW-SSE Fuyun strike-slip fault, on the NWW-SEE Irtysh strike-slip fault, and on the NW-SE Kurti reverse fault is up to 67.22%-91.36%. Therefore, the predictedΔCFS suggests that the impact of the 1931 M_(w)7.8 Fuyun earthquake on seismic activity around the Altai mountains is still significant as to hasten occurrence of the 2003 M_(w)7.2 Chuya earthquake at a relatively far distance and to trigger its aftershocks in the near-field even after several decades of the mainshock.

Isolation and Functional Characterization of a B3 Transcription Factor Gene <i>FUSCA3</i>Involved in Pre-Harvest Sprouting Resistance in Wheat

Pre-harvest sprouting (PHS) reduces yields and grain quality, resulting in seriously economic losses in wheat. It has been showed that PHS is significantly correlated to seed dormancy levels. FUSCA3 (FUS3) gene is considered to be the key regulator of seed dormancy. However, little information is available about the function of FUS3 gene (TaFUS3) in wheat. In this study, three homologous genes were identified in wheat grain, and their functions were investigated by gene silencing. Three full-length DNA (3477, 3534 and 3501 bp) and cDNA (1015, 1012 and 1015 bp) sequences encoding a B3 transcription factor, designated TaFUS3-3A, TaFUS3-3B and TaFUS3-3D, were first isolated from common wheat. The transcription of three TaFUS3 genes in seed development and germination process was detected. TaFUS3-3B and TaFUS3-3D had similar expression profiles, and high levels of gene transcripts were detected in seeds at 25 DAP (days after pollination) and after 24 h of imbibition. However, the transcription of TaFUS3-3A was not detected. Silencing of TaFUS3 in common wheat spikes resulted in increased seed germination and PHS. Compared with wild-type, the TaFUS3-silenced plants showed increased expression of genes related to GA biosynthesis and ABA metabolism, and decreased expression of genes associated with ABA biosynthesis. Moreover, silencing of TaFUS3 in wheat plants led to a decrease in embryo sensitivity to ABA and changed the expression of genes involved in ABA signal transduction. The results of gene silencing indicated that TaFUS3 plays a positive role in wheat seed dormancy and PHS-resistance, which might be associated with ABA, GA level and signal transduction.

Molecular characterization and expression analysis of three homoeologous Ta14S genes encoding 14-3-3 proteins in wheat(Triticum aestivum L.)

The purpose of this study was to characterize Ta14 S homoeologs and assess their functions in wheat seed development.The genomic and c DNA sequences of three Ta14 S homoeologous genes encoding 14-3-3 proteins were isolated.Sequence analysis revealed that the three homoeologs consisted of five exons and four introns and were very highly conserved in the coding regions and in exon/intron structure,whereas the c DNA sequences were variable in the 5′ and 3′-UTR.The three genes,designated as Ta14S-2A,Ta14S-2B and Ta14S-2D,were located in homoeologous group 2 chromosomes.The polypeptide chains of the three Ta14 S genes were highly similar.These genes were most homologous to Hv14 A from barley.Real-time quantitative PCR indicated that the three Ta14 S genes were differentially expressed in different organs at different developmental stages and all exhibited greater expression in primary roots of 1-day-old germlings than in other tissues.Comparison of the expression patterns of the three homoeologous genes at different times after pollination also revealed that their expression was developmentally regulated.The transcription of Ta14S-2B was clearly higher during seed germination,whereas expressions of Ta14S-2A and Ta14S-2D were up-regulated at the beginning of seed imbibition(0–12 h),but declined thereafter.The results suggested that the three Ta14 S homoeologous genes have regulatory roles in seed development and germination.

独柱塔宽幅钢箱梁斜拉桥主梁设计研究

随着铁路安全要求的越来越严格,上跨铁路的市政工程桥梁跨径正在逐渐增大。为解决跨越高速铁路及大型铁路编组站的建设难题,以一座大跨度独柱中央索转体斜拉桥为研究对象,针对主梁设计进行详细研究。跨铁路通道一般为稀缺通道资源,搭载交通功能需求多,桥面往往较宽,若采用混凝土截面,其横向应力很难有效控制,且施工质量很难保证。钢混组合梁工艺复杂且需向铁路局要天窗点,施工时间长,考虑跨越铁路尽量施工方便且对铁路影响降到最低,同时尽量降低转体重量,推荐钢箱梁作为跨铁路桥主梁结构形式。根据斜拉索布置形式及整、分幅钢箱梁类型,共对三种钢主梁横向布置进行比选。由于采用独柱形桥塔且塔高较低,钢箱梁两侧布置的斜拉索将会倾入行车道净空,同时分幅钢箱梁中央护栏区仍存在车辆或异物坠入桥下铁路的危险,推荐中央索面整幅钢箱梁结构形式。在确定斜拉桥主梁结构形式为整幅钢箱梁的基础上,进一步优化钢箱梁梁高。以斜拉桥结构受力状态和钢材用量为优化目标,初步选定三种钢箱梁梁高方案,其截面高度分别为3.0,3.3,3.5 m。从结构受力状态和工程经济性两个方面综合考虑,3.3 m梁高方案对于主梁、桥塔受力及工程材料的节约方面为最佳配置。为研究宽幅钢箱梁受力性能,以独柱塔宽幅钢箱梁斜拉桥工程实例,开展宽幅钢箱梁设计研究。基于极限状态法,依托JTG D64—2015《公路钢结构桥梁设计规范》开展了钢箱梁静载计算和疲劳计算分析。静载分析包括加载模式、钢箱梁桥面板刚度条件等指标的确定,并基于ANSYS开展了标准钢箱梁和压重区钢箱梁的空间局部应力分析;疲劳验算通过选择合理的疲劳荷载模型和全面考虑疲劳荷载的不同加载位置。静载计算和疲劳验算结果表明:大桥钢箱梁的静载变形和应力满足JTG D64—2015要求,各构件和连接的疲劳应力幅均小于规范限值,并有适当的安全富余,疲劳性能良好。采用杆系、板壳混合有限元法建立混合有限元模型,对独柱宽幅钢箱梁斜拉桥控制性区域跨中节段、塔梁交汇区域与边跨辅助墩区域进行剪力滞效应分析,提炼参数指标,对设计起到了重要指导作用。独柱塔宽幅钢箱斜拉桥主梁具有良好的经济性和美观性,可为大跨度宽幅桥面结构提供借鉴和参考。

Identification of Global DNA Methylation Signatures in Glioblastoma-Derived Cancer Stem Cells

Glioblastoma （GBM） is the most common and most aggressive primary brain tumor in adults. The existence of a small population of stem-like tumor cells that efficiently propagate tumors and resist cytotoxic therapy is one proposed mechanism leading to the resilient behavior of tumor cells and poor prognosis. In this study, we performed an in-depth analysis of the DNA methylation landscape in GBM- derived cancer stem ceils （GSCs）. Parallel comparisons of primary tumors and GSC lines derived from these tumors with normal controls （a neural stem cell （NSC） line and normal brain tissue） identified groups of hyper- and hypomethylated genes that display a trend of either increasing or decreasing methylation levels in the order of controls, primary GBMs, and their counterpart GSC lines, respectively. Interestingly, concurrent promoter hypermethylation and gene body hypomethylation were observed in a subset of genes including MGMT, AJAP1 and PTPRN2. These unique DNA methylation signatures were also found in primary GBM-derived xenograft tumors indicating that they are not tissue culture-related epigenetic changes. Integration of GSC-specific epigenetic signatures with gene expression analysis further identified candidate tumor suppressor genes that are frequently down-regulated in GBMs such as SPINT2, NEFM and PENK. Forced re-expression of SPINT2 reduced glioma cell proliferative capacity, anchorage independent growth, cell motility, and tumor sphere formation in vitro. The results from this study demonstrate that GSCs possess unique epigenetic signatures that may play important roles in the pathogenesis of GBM.