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91.
92.
Meng Zhang Xinkai Ding Weixiang Peng Hongliang Zhang Bingjie Wu 《Molecular simulation》2019,45(3):178-185
Radiation damage in reactor materials caused by the collision of the fast neutrons has a great impact on the reliability and safety of nuclear reactors. The element vanadium has attracted interest in many fields due to its advantageous properties in alloys. Thus, molecular dynamics simulation (MD) and first-principles calculation have been executed here to explore the radiation-resistant properties of five materials adding a layer in the bulk (pure iron and four types of Fe–V alloys containing 10%-40% V). The following results were inferred from these simulations. Firstly, the number of Frenkel pairs (FPs) at the stable quenching stage in the bulk decreases when the Fe–V alloy is added as an anti-radiation layer to the bulk. These benefits are evident for the Fe80V20 and alloy layers with more vanadium. The main reason is that the Fe–V binding energy is greater than the Fe-Fe binding energy, which can make the Primary Knock-On atom (PKA) lose more energy at the Fe–V alloy layer. Secondly, the average value of point-defect, cluster and defect clustered fractions in the bulk of Fe–V alloy is smaller than that in the pure iron at the stable quenching stage, especially for the Fe80V20 alloy. 相似文献
93.
Zi-Yun Yi Qiu-Xia Liang Tie-Gang Meng Jian Li Ming-Zhe Dong Yi Hou 《Cell cycle (Georgetown, Tex.)》2019,18(4):395-412
PKCβI, a member of the classical protein kinase C family, plays key roles in regulating cell cycle transition. Here, we report the expression, localization and functions of PKCβI in mouse oocyte meiotic maturation. PKCβI and p-PKCβI (phosphor-PKCβI) were expressed from germinal vesicle (GV) stage to metaphase II (MII) stage. Confocal microscopy revealed that PKCβI was localized in the GV and evenly distributed in the cytoplasm after GV breakdown (GVBD), and it was concentrated at the midbody at telophase in meiotic oocytes. While, p-PKCβI was concentrated at the spindle poles at the metaphase stages and associated with midbody at telophase. Depletion of PKCβI by specific siRNA injection resulted in defective spindles, accompanied with spindle assembly checkpoint activation, metaphase I arrest and failure of first polar body (PB1) extrusion. Live cell imaging analysis also revealed that knockdown of PKCβI resulted in abnormal spindles, misaligned chromosomes, and meiotic arrest of oocytes arrest at the Pro-MI/MI stage. PKCβI depletion did not affect the G2/M transition, but its overexpression delayed the G2/M transition through regulating Cyclin B1 level and Cdc2 activity. Our findings reveal that PKCβI is a critical regulator of meiotic cell cycle progression in oocytes.
Abbreviations: PKC, protein kinase C; COC, cumulus-oocyte complexes; GV, germinal vesicle; GVBD, germinal vesicle breakdown; Pro-MI, first pro-metaphase; MI, first metaphase; Tel I, telophase I; MII, second metaphase; PB1, first polar body; SAC, spindle assembly checkpoint 相似文献
94.
95.
禽致病性大肠杆菌毒力基因多重PCR方法的建立和应用 总被引:1,自引:0,他引:1
【目的】建立禽致病性大肠杆菌(Avian pathogenic Escherichia coli,APEC)黏附相关基因、侵袭及毒素相关基因、抗血清存活相关基因及铁转运相关基因的多重PCR方法,实现禽致病性大肠杆菌毒力基因的简便、快速检测。【方法】根据GenBank公布的基因序列,设计合成18对特异性引物,通过条件优化,建立四组多重PCR体系,并通过模板倍比稀释检测各组多重PCR的灵敏性。利用多重PCR检测100株APEC毒力基因的分布,验证多重PCR方法的可行性。【结果】根据PCR扩增片段大小判定,上述四组多重PCR体系均能同时扩增出该组中的各个毒力基因,且灵敏度分别为:103CFU、103CFU、105CFU、105CFU细菌和1ng、1ng、10ng、10ng DNA。100株APEC的毒力因子检测结果显示,多重PCR和单基因PCR结果一致。【结论】建立的四组多重PCR方法能够简便、快速地检测禽致病性大肠杆菌的毒力基因,可用于毒力基因的鉴定以及流行病学调查。 相似文献
96.
SDS-PAGE法测定His-tag融合蛋白分子量产生偏差的原因 总被引:10,自引:0,他引:10
Histag/NiNTA系统是新发展起来的一个亲和纯化重组蛋白的有用工具,现常用于基因编码产物的特性研究中。SDSPAGE是实验室测定蛋白质分子量通常采用的方法,而许多实验室用此方法检测Histag融合蛋白时却常发现测得的分子量偏大,产生偏差的原因尚未阐明。为弄清这一问题,本实验室在研究一个Histag融合蛋白P73His时,首先用SDSPAGE法测得其分子量确实比理论计算值大,然后对其进行C末端氨基酸顺序测定、电喷雾质谱分析,结果证实其实际分子量与理论值一致。酶切去除包括Histag在内的部分肽段使SDSPAGE法测量蛋白分子量的偏差大大降低,证实Histag确实是造成偏差的原因之一。推测由于Histag中的碱性氨基酸的作用造成蛋白在SDSPAGE中迁移变慢,而导致偏差。这一现象值得引起有关研究者的注意。 相似文献
97.
钙调素抑制剂——三氟拉嗪对肿瘤细胞增殖和微管组装的影响 总被引:1,自引:0,他引:1
本文用钙调素抑制剂——三氟拉嗪处理人胃癌MGC-803细胞,用免疫荧光细胞化学方法,放射免疫法和速流荧光分析等方法研究了钙调素对细胞增殖,环核苷酸代谢及微管组装,有丝分裂等细胞功能的调节作用。实验结果表明,TFP明显地抑制了人胃癌细胞的增殖,这种抑制增殖的作用,具有剂量和时间依赖关系,细胞群体中G_1期细胞增多,S期细胞下降,DNA合成明显地受到抑制。TFP处理的胃癌细胞仅在短时间内(5'-30')cAMP含量升高,cGMP浓度降低,cAMP/ ??cGMP比值比对照组高4.4倍,但此后环核苷酸含量又很快恢复到对照组水平。本实验还观察到TFP处理后的MGC-803细胞胞质铺展,细胞形态的改变与胞质微管的分布有密切联系,实验结果表明TFP加强了人胃癌细胞MTOC对微管的组装能力,使微管分布得到恢复,微管纤维呈放射状延伸到细胞边缘,充满胞浆,使细胞呈现出展平的多边形,趋向于正常上皮细胞形态的变化,本实验结果表明TFP抑制癌细胞增殖及使微管组装加强可能是通过对CaM活性的抑制作用。此结果有助于说明转化细胞内钙调素的变化,可能是与转化细胞增殖失控和胞质微管消退有关。 相似文献
98.
99.
100.
Zhang Y Meng Q Jiang T Wang H Xie L Zhang R 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2003,135(1):43-54
Iron is one of the most important minor elements in the shell of bivalves. This study was designed to investigate the involvement of ferritin, the principal protein for iron storage, in shell formation. A novel ferritin cDNA from the pearl oyster (Pinctada fucata) was isolated and characterized. The ferritin cDNA encodes a 206 amino acid polypeptide, which shares high similarity with snail soma ferritin and the H-chains of mammalian ferritins. Oyster ferritin mRNA shows the highest level of expression in the mantle, the organ for shell formation. In situ hybridization analysis revealed that oyster ferritin mRNA is expressed at the highest level at the mantle fold, a region essential for metal accumulation and contributes to metal incorporation into the shell. Taken together, these results suggest that ferritin is involved in shell formation by iron storage. The identification and characterization of oyster ferritin also helps to further understand the structural and functional properties of molluscan ferritins. 相似文献