一种制备口蹄疫抗原和高免血清的新方法

口蹄疫是一种一类传染病,其病原为口蹄疫病毒(FMDV)。FMDV衣壳蛋白VP1含有中和性抗原表位。本研究合成了编码O型FMDVVP1蛋白中和性抗原表位的双拷贝DNA片段,将其克隆于原核表达载体pGEX-6p-1中,以获得的重组质粒转化大肠杆菌,然后用IPTG进行诱导,表达出了大小约为33kDa的GST融合重组蛋白,Westernblotting分析证实,重组蛋白可以被O型FMDV抗血清所识别。用纯化的重组蛋白免疫豚鼠制备高免血清,ELISA检测表明,免疫后的豚鼠血清抗体滴度可达1∶20560以上。本研究提供了一种制备口蹄疫抗原和高免血清的新方法。     

Symptoms and Prepenetration Events Associated with the Infection of Common Bean by the Anamorph and Teleomorph of Glomerella cingulata f.sp. phaseoli

Glomerella cingulata f.sp. phaseoli and Colletotrichum lindemuthianum are the teleomorph and anamorph, respectively, of the pathogen causing anthracnose in common bean. The mechanisms relating to the sexual reproduction of this plant pathogen are still unclear, as are the infection structures involved and the symptoms produced. In the present study, bean plants were inoculated with ascospores and conidia, and the events taking place within the following 120 h were investigated using light microscopy and scanning electron microscopy. The symptoms exhibited by plants inoculated with the ascospores were milder than in those inoculated with conidia. Microscopy revealed that most of ascospores produced germ tubes and appressoria at an early stage (24 h after inoculation). From 48 h onwards, the formation of hyphae and the production of germ tubes and appressoria were great. In contrast, infections originating from conidia developed more slowly, and at 24 and 48 h, many non‐germinated conidia were present, whereas only few conidia developed germ tubes and appressoria. Ascospore germination and appressorium formation were similar on both resistant and susceptible cultivars. Hence, the symptoms and the temporal sequence of events associated with the infection of bean plants by the two fungal forms differed, although the structures produced were similar. This is the fist report comparing symptoms and prepenetration events between anamorph and teleomorph of G. cingulata f.sp. phaseoli in common bean.     

Oxidized LDL up-regulates the ascorbic acid transporter SVCT2 in endothelial cells

Endothelial dysfunction is an early manifestation of atherosclerosis caused in part by oxidized LDL (oxLDL). Since vitamin C, or ascorbic acid, prevents several aspects of endothelial dysfunction, the effects of oxLDL on oxidative stress and regulation of the ascorbate transporter, SVCT2, were studied in cultured EA.hy926 endothelial cells. Cells cultured for 18 h with 0.2 mg/ml oxLDL showed increased lipid peroxidation that was prevented by a single addition of 0.25 mM ascorbate at the beginning of the incubation. This protection caused a decrease in intracellular ascorbate, but no change in the cell content of GSH. In the absence of ascorbate, oxLDL increased SVCT2 protein and function during 18 h in culture. Although culture of the cells with ascorbate did not affect SVCT2 protein expression, the oxLDL-induced increase in SVCT2 protein expression was prevented by ascorbate. These results suggest that up-regulation of endothelial cell SVCT2 expression and function may help to maintain intracellular ascorbate during oxLDL-induced oxidative stress, and that ascorbate in turn can prevent this effect.     

Galectin-1 Enhances Astrocytic BDNF Production and Improves Functional Outcome in Rats Following Ischemia

Galectin-1, an endogenous mammalian lectin, has been implicated in a variety of CNS disorders. However, its role in cerebral ischemia is still elusive. In the present study, we investigated the effect of recombinant galectin-1 on production of astrocytic brain-derived neurotrophic factor (BDNF) and functional recovery following ischemia. Endogenous galectin-1 was found to be markedly upregulated, paralleled with increased astrocytic BDNF production under ischemic conditions both in vitro and in vivo. Administration of galectin-1significantly enhanced the expression and secretion of astrocytic BDNF in dose dependent manner. Moreover, rats subjected to photochemical cerebral ischemia showed reduced neuronal apoptosis in ischemic boundary zone and improved functional recovery after brain infusion of galectin-1 (1 μg/days, 7 days). These results suggest that induction of BDNF in astrocytes by galectin-1 may be a promising intervention to attenuate brain damage after stroke.     

骨骼的内分泌功能

既往认为骨骼是支持机体基本结构和参与运动及钙磷代谢的主要器官。近年发现组成骨骼的成骨细胞和破骨细胞能合成和分泌多种骨调节蛋白、生长因子、脂肪因子、炎症因子和心血管活性肽等多种生物活性物质,以旁/自分泌方式调节骨骼系统功能,并能通过血液循环远距分泌的方式,调节机体能量代谢、炎症反应和内分泌稳态等。     

Clusterin induces CXCR4 expression and migration of cardiac progenitor cells

Clusterin (CST) is a stress-responding protein with multiple biological functions, including the inhibition of apoptosis and inflammation and transport of lipids. It may also participate in cell traffic and migration. In the process of post-infarct cardiac tissue repair, stem cells migrate into the damaged myocardium under the influence of chemoattractive substances such as stromal cell-derived factor (SDF). This study aimed at testing whether CST enhances expression of stem cell homing receptor and migration of cardiac progenitor cells (CPCs). CPCs isolated from fetal canine hearts transduced by CST cDNA expressed high levels of CXCR4, a receptor for SDF-1. The transfected cells also showed an increased migratory response to SDF-1 stimulation. The SDF-1-mediated migration of the CST-expressing CPCs was attenuated by PI3 kinase inhibitor LY294002 but not by mitogen-activated protein/ERK kinase inhibitor PD98059. Analysis of cell cycle by flow cytometry revealed no significant difference in cell cycle between the transduced and control CPCs. Thus, CST expression may increase CPCs migration via increasing CXCR4 expression and SDF-1/chemokine receptor signaling in a PI3/Akt-dependent manner.     

Cytotoxic cassaine diterpenoid–diterpenoid amide dimers and diterpenoid amides from the leaves of Erythrophleum fordii

Detailed phytochemical investigation from the leaves of Erythrophleum fordii resulted in the isolation of 13 compounds, including three cassaine diterpenoid–diterpenoid amide dimers (1, 3 and 5), and seven cassaine diterpenoid amides (6 and 8–13), together with three previously reported ones, erythrophlesins D (2), C (4) and 3β-hydroxynorerythrosuamide (7). Compounds 1, 3 and 5 are further additions to the small group of cassaine diterpenoid dimers represented by erythrophlesins A–D. Their structures were determined by analysis of extensive one- and two-dimensional NMR experiments and ESIMS methods. Cytotoxic activities of the isolated compounds were tested against HCT-8, Bel-7402, BGC-823, A549 and A2780 human cancer cell lines in the MTT test. Results showed that compounds 1 and 3–5 exhibited significantly selective cytotoxic activities (IC₅₀ < 10 μM) against these cells, respectively.     

Molecular cloning and characterization of a novel metagenome-derived multicopper oxidase with alkaline laccase activity and highly soluble expression

Lac591, a gene encoding a novel multicopper oxidase with laccase activity, was identified through activity-based functional screening of a metagenomic library from mangrove soil. Sequence analysis revealed that lac591 encodes a protein of 500 amino acids with a predicted molecular mass of 57.4 kDa. Lac591 was overexpressed heterologously as soluble active enzyme in Escherichia coli and purified, giving rise to 380 mg of purified enzyme from 1 l induced culture, which is the highest expression report for bacterial laccase genes so far. Furthermore, the recombinant enzyme demonstrated activity toward classical laccase substrates syringaldazine (SGZ), guaiacol, and 2, 6-dimethoxyphenol (2, 6-DMP). The purified Lac591 exhibited maximal activity at 55°C and pH 7.5 with guaiacol as substrate and was found to be stable in the pH range of 7.0–10.0. The substrate specificity on different substrates was studied with the purified enzyme, and the optimal substrates were in the order of 2, 6-DMP > catechol > α-naphthol > guaiacol > SGZ > 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid). The alkaline activity and highly soluble expression of Lac591 make it a good candidate of laccases in industrial applications for which classical laccases are unsuitable, such as biobleaching of paper pulp and dyestuffs processing.