三叶崖爬藤中的新黄酮碳甙

从三叶崖爬藤(Tetrastigma hemsleyanum Diels et Gilg.)的95%乙醇提取物中分离得到3个黄酮碳甙,经化学方法和光谱分析鉴定为:5,7,4′-三羟基黄酮-6-α-L-吡喃鼠李糖(1-4)-α-L-吡喃阿拉伯糖甙(1),5,7,4′-三羟基黄酮-8-α-L-吡喃鼠李糖(1-4)-α-L-吡喃阿拉伯糖甙(2),5,7,4′-三羟基黄酮-6,8-二-C-β-D-吡喃葡萄糖甙(3),1和2为新化合物,分别命名为崖爬藤甙和异崖爬藤甙.     

Expression of the tobacco mosaic virus movement protein alters starch accumulation inNicotiana benthamiana

Nicotiana benthamiana plants were transformed with the movement protein (MP) gene of tobacco mosaic virus (TMV), usingAgrobacterium-mediated transformation. Plants regenerated from the transformed cells accumulated 30-kDa MP and complemented the activity of TMV MP when infected with chimeric TMVs containing defective MR These transgenic plants displayed stunting, pale-green leaves, and starch accumulations, indicating that TMV MP altered the carbon partitioning for leaves involved in TMV cell-to-cell movement.     

Sphingosylphosphorylcholine-induced contraction of feline ileal smooth muscle cells is mediated by Gαi3 protein and MAPK

We studied the mechanism of sphingosylphosphorylcholine (SPC)-induced contraction in feline ileal smooth muscle cells. Western blotting revealed that G protein subtypes of Gα_i1, Gα_i3 and Gα_o existed in feline ileum. Gα_i3 antibody penetration into permeabilized cells decreased SPC-induced contraction. In addition, incubation of [³⁵S]guanosine 5′-O-(3-thiotriphosphate) ([³⁵S]GTPγS) with membrane fraction increased its binding to Gα_i3 subtype after SPC treatment, suggesting that the signalling pathways invoked by SPC were mediated by Gα_i3 protein. MAPK kinase (MEK) inhibitor PD98059 blocked the contraction significantly, but p38 mitogen-activated protein kinase (MAPK) inhibitor SB202190 did not. Chelerythrine and neomycin also inhibited the contraction. However, cotreatment of PD98059 and chelerythrine showed no significant difference. Phosphorylation of p44/42 MAPK was increased by SPC treatment, which was reversed by pretreatment of inhibitors of signalling molecules that decreased SPC-induced contraction previously. The same result was obtained in the assay of MAPK activity.     

烟草质体分裂蛋白NtFtsZs在大肠杆菌中的定位分析

分别构建了两个烟草(Nicotiana tabacum L.)质体分裂基因NtFtsZ1和NtFtsZ2与编码绿色荧光蛋白的gfpS65A、V68L、S72A基因相融合的原核表达载体,并导入大肠杆菌( Escherichia coli ) JM109菌株中进行表达.全长NtFtsZs∶GFP融合蛋白在菌体中有规律地定位,暗示NtFtsZs能识别大肠杆菌潜在的分裂位点,并能与大肠杆菌的内源FtsZ发生聚合作用;融合蛋白的诱导表达抑制了宿主菌的分裂,形成了明显的丝状菌体,证明真核生物的 ftsZ 基因与大肠杆菌的 ftsZ 基因有相似的作用.同时构建了NtFtsZs不同缺失的原核表达载体,对这两个基因所编码蛋白不同结构域的功能做了初步分析.实验结果表明,烟草FtsZ蛋白的C端结构域与其在大肠杆菌细胞中的正确定位有关;而N端结构域与NtFtsZs∶GFP融合蛋白的聚合有关.     

Matrix metalloproteinase-14 is a mechanically regulated activator of secreted MMPs and invasion

Matrix metalloproteinases (MMPs) are extracellular matrix (ECM) degrading enzymes and have complex and specific regulation networks. This includes activation interactions, where one MMP family member activates another. ECM degradation and MMP activation can be initiated by several different stimuli including changes in ECM mechanical properties or intracellular contractility. These mechanical stimuli are known enhancers of metastatic potential. MMP-14 facilitates local ECM degradation and is well known as a major mediator of cell migration, angiogenesis and invasion. Recently, function blocking antibodies have been developed to specifically block MMP-14, providing a useful tool for research as well as therapeutic applications. Here we utilize a selective MMP-14 function blocking antibody to delineate the role of MMP-14 as an activator of other MMPs in response to changes in cellular contractility and ECM stiffness. Inhibition using function blocking antibodies reveals that MMP-14 activates soluble MMPs like MMP-2 and -9 under various mechanical stimuli in the pancreatic cancer cell line, Panc-1. In addition, inhibition of MMP-14 abates Panc-1 cell extension into 3D gels to levels seen with non-specific pan-MMP inhibitors at higher concentrations. This strengthens the case for MMP function blocking antibodies as more potent and specific MMP inhibition therapeutics.     

仿脑组织体模研究进展

仿脑组织体模是指可以有效模拟人脑组织形状、性质的等效材料组织或数字模型,可以在实验中代表人脑组织的某些生理特性从而达到特定的研究目标,根据其物理形态,通常可分为固体、液体、数字体模3类。仿脑组织体模具有安全经济,配置简单并且可重复使用的优势,被广泛应用于脑部疾病诊断、系统安全性评估等研究。本文就仿脑组织体模的分类、物理特性和脑科学研究应用3方面进行论述,在阐述当前仿脑组织体模与真实脑组织存在一定性质差异的同时也说明其在替代真实脑组织实验上有良好的应用前景。     

Dieckol,a natural polyphenolic drug,inhibits the proliferation and migration of colon cancer cells by inhibiting PI3K,AKT, and mTOR phosphorylation

This study investigated that dieckol (DKL), a natural drug, inhibits colon cancer cell proliferation and migration by inhibiting phosphoinositide-3-kinase (PI3K), protein kinase B (AKT), and mammalian target of rapamycin (mTOR) phosphorylation in HCT-116 cells. The cells were treated with DKL in various concentrations (32 and 50 μM) for 24 h and then analyzed for various experiments. MTT (tetrazolium bromide) and crystal violet assay investigated DKL-mediated cytotoxicity. Dichlorodihydrofluorescein diacetate staining was used to assess the reactive oxygen species (ROS) measurement, and apoptotic changes were studied by dual acridine orange and ethidium bromide staining. Protein expression of cell survival, cell cycle, proliferation, and apoptosis protein was evaluated by western blot analysis. Results indicated that DKL produces significant cytotoxicity in HCT-116, and the half-maximal inhibitory concentration was found to be 32 μM for 24-h incubation. Moreover, effective production of ROS and enhanced apoptotic signs were observed upon DKL treatment in HCT-116. DKL induces the expression of phosphorylated PI3K, AKT, and mToR-associated enhanced expression of cyclin-D1, proliferating cell nuclear antigen, cyclin-dependent kinase (CDK)-4, CDK-6, and Bcl-2 in HCT-116. In addition, proapoptotic proteins such as Bax, caspase-9, and caspase-3 were significantly enhanced by DKL treatment in HCT-116. Hence, DKL has been considered a chemotherapeutic drug by impeding the expression of PI3K-, AKT-, and mTOR-mediated inhibition of proliferation and cell cycle-regulating proteins.