Impact of nuclear actin on the prophase chromosome construction of Physarum polycephalum

A cell-free system efficiently promoting mitosis has been developed using the precise natural synchronous plasmodium of Physarum polycephalum. The content changes of nuclear cyclin B were exploited to represent the prophase process of Physarum polycephalum. The possible function of nuclear actin on chromosome construction was investigated by detecting the content changes of nuclear cyclin B in the late G2 phase nuclei treated with cytochalasin B and incubated in the cell-free system. Our results showed that nuclear actin plays an important role in the process of the chromosome construction.     

Tilting Ratchet肌动蛋白双足运动模型的研究

针对肌动蛋白两足交替行走的事实提出TTilting ratchet双足运动模型,并对其运动轨道进行了数学模拟．从而说明所提出的模型能够清楚的描述这种交替行走的运动机制,表明了模型的可行性和有效性．同时还对这种模型中的粒子运动速度和系统效率进行了研究,给出了一些数值模拟结果．     

Molecular mechanisms of phagocytic uptake in mammalian cells

Phagocytosis is a highly conserved, complex process that has evolved to counter the constant threat posed by pathogens, effete cells and debris. Classically defined as a mechanism for internalising and destroying particles greater than 0.5 mum in size, it is a receptor-mediated, actin-driven process. The best-studied phagocytic receptors are the opsono-receptors, FcgammaR and CR3. Phagocytic uptake involves actin dynamics including polymerisation, bundling, contraction, severing and depolymerisation of actin filaments. Recent evidence points to the importance of membrane remodelling during phagocytosis, both in terms of changes in lipid composition and delivery of new membrane to the sites of particle binding. Here we review the molecular mechanisms of phagocytic uptake and some of the strategies developed by microbial pathogens to manipulate this process.     

鸭胚B淋巴细胞中间纤维的研究

从26天北京鸭胚胎的腔上囊中分离B淋巴细胞。应用细胞选择性系列抽提方法与DGD包埋——去包埋剂的电镜制样技术相结合,显示出了B细胞的中间纤维的超微结构及分布特点:纤维致密交织呈网络状,其特点是均匀地遍布于整个胞质空间,纤维单丝直径在9—11nm。间接免疫荧光实验结果表明,B细胞的胞质对波形蛋白单抗呈阳性反应,且也显示出了波形纤维呈网络状的结构形式。本文采用单向电泳、双向电泳和蛋白质免疫印迹技术,证实了B细胞中间纤维波形蛋白的分子量约为55KD。     

Icariin suppresses bone resorption activity of rabbit osteoclasts in vitro

The effect of icariin on the bone resorption activity of rabbit osteoclasts is assessed in vitro. Osteoclasts were isolated from Japanese white rabbits and cultured on plates with a sterilized bone slice in each well. After treatment with icariin at various concentrations, the bone resorption activity of osteoclasts was evaluated by examining pit areas, superoxide anion (·O2-) generation, size and number of actin rings and intracellular calcium concentration [Ca2 ]i. As revealed by these data, icariin elicited continuous decline of [Ca2 ]i, making actin ring constricted and ·O2- generation decreased. These events resulted in smaller and fewer pits which indicate suppressed bone resorption activity of rabbit osteoclasts by icariin.     

The effects of ethanol on embryonic actin: A possible role in teratogenesis

Summary When the neural crest is cultured in the long or short term presence of ethanol, monoclonal anti-actin reveals the development of a disorganized actin cytoskeleton. In the long term, many cells fail to differentiate morphologically, whereas in the short term already differentiated cells rapidly alter their shape and their cell-to-cell contacts.     

三叶青两个肌动蛋白基因片段的克隆及其分析

根据GenBank中登录的植物肌动蛋白保守序列设计1对引物,对三叶青的块根进行RT‐PCR ,在1次扩增中得到2个不同的肌动蛋白基因片段,分别命名为 ThAct1和 ThAct2．测序结果显示：ThAct1基因片段长度为867 bp ,编码252个氨基酸;ThAct2基因片段长度为1079 bp ,编码152个氨基酸．经Blast分析,ThAct1和ThAct2基因均属于NBD＿sugar‐kinase＿HSP70＿actin superfamily家族,与其它物种Actin基因序列和编码的蛋白质均具有同源性．RT‐PCR结果初步表明：在茎、普通根和块根中 ThAct1和 ThAct2基因的表达未见差异;但在叶中,ThAct1的表达稍强,而 ThAct2的表达稍弱．另外,在茎、普通根和块根中,ThAct1表达比ThAct2强;但在叶中 ThAct1表达比ThAct2弱．结果为分析肌动蛋白基因在三叶青块根发育中的功能奠定了基础;获得的肌动蛋白也可以作为内参基因,在三叶青功能基因组的研究中用于其它基因的定量表达分析．     

Effect of TiO2@SiO2 nanoparticles on the mechanical and UV-resistance properties of polyphenylene sulfide fibers

In order to avoid the inherent photo-catalysis and aggregation of TiO2 in PPS, TiO2 nanoparticles were coated with SiO2 layers, which were chosen as the UV absorbent to improve the UV stability of polyphenylene sul fi de(PPS) fi ber. The PPS–TiO2@SiO2 nanocomposites fi bers were prepared via melt spinning, and the nanocomposites fi bers displayed different crystallization behaviors on variation of the diameters of TiO2@SiO2 nanoparticles, as con fi rmed by Differential Scanning Calorimetry(DSC). The spinnability, breaking strength and UV-resistance properties of PPS nanocomposites fi bers, as measured by homemade melt spinning machine, Xenon-lamp Weather Resistance Test Chamber and Yarn Tensile Tester, manifested the dependence on the diameters. The addition of nanoparticles with the diameter of 25 nm improved the spinnability and the mechanical performance of PPS most, which is attributed to the heterogeneous nucleation effect of nanoparticles. The UVresistance properties of the PPS nanocomposites were improved by the addition of TiO2@SiO2 nanoparticles. After aging for 180 h, PPS nanocomposites fi ber still maintained a high strength.