水龙骨中总黄酮的含量分析

目的:对水龙骨中总黄酮含量进行测定,为水龙骨质量评价提供依据.方法:芦丁-UV方法进行测定.结果:总黄酮在0.001 68～0.067 2 mg/mL范围有良好的线性关系(r=0.999 1),加样回收率为98.23%,RSD=3.52%.结论:该法样品处理简单、迅速,可以做为水龙骨中总黄酮的含量测定方法.     

Regulation of Actin Dynamics in Pollen Tubes: Control of Actin Polymer Level

Actin cytoskeleton undergoes rapid reorganization in response to internal and external cues. How the dynamics of actin cytoskeleton are regulated, and how its dynamics relate to its function are fundamental questions in plant cell biology. The pollen tube is a well characterized actin-based cell morphogenesis in plants. One of the striking features of actin cytoskeleton characterized in the pollen tube is its surprisingly low level of actin polymer. This special phenomenon might relate to the function of actin cytoskeleton in pollen tubes. Understanding the molecular mechanism underlying this special phenomenon requires careful analysis of actin-binding proteins that modulate actin dynamics directly. Recent biochemical and biophysical analyses of several highly conserved plant actin-binding proteins reveal unusual and unexpected properties, which emphasizes the importance of carefully analyzing their action mechanism and cellular activity. In this review, we highlight an actin monomer sequestering protein, a barbed end capping protein and an F-actin severing and dynamizing protein in plant. We propose that these proteins function in harmony to regulate actin dynamics and maintain the low level of actin polymer in pollen tubes.     

Differences in growth and physiological traits of two poplars originating from different altitudes as affected by UV‐B radiation and nutrient availability

Cuttings of Populus kangdingensis and Populus cathayana originating from altitudes of 3500 and 1500 m in southwestern China, respectively, were grown for one growing season in the field under ambient or ambient plus supplemental ultraviolet‐B (UV‐B) radiation with two levels of nutrients. In both species, enhanced UV‐B radiation significantly increased UV‐B absorbing compounds and guaiacol peroxidase (GPX) activity, while no significant effects were observed in photosynthetic pigments and proline content. On the other hand, cuttings grown with high‐nutrient availability had larger leaf area, higher total biomass and GPX activity as well as higher water use efficiency (WUE) (as measured by stable carbon isotope composition, δ¹³C) when compared with low‐nutrient conditions, while UV‐B absorbing compounds and ascorbic acid (AsA) content significantly decreased. Differences in responses to enhanced UV‐B radiation and nutrient availability were observed between the two species. Nutrient‐induced increases in chlorophyll a, chlorophyll b and total chlorophyll as well as in carotenoids were greater in P. kangdingensis than in P. cathayana. In P. cathayana, enhanced UV‐B radiation significantly decreased leaf area and total biomass, while it significantly increased WUE and ascorbate peroxidase (APX). In contrast, such changes were not observed in P. kangdingensis. In addition, the effects of enhanced UV‐B radiation on leaf area, total biomass and UV‐B absorbing compounds were closely related to the nutrient status. Our results indicated that P. kangdingensis, which originates from the altitude of 3500 m and is apparently adapted to low‐nutrient and high‐UV‐B habitats, exhibits better tolerance to enhanced UV‐B radiation and greater growth under low‐nutrient availability than does P. cathayana originating from the altitude of 1500 m.     

伤寒头对CCl_4致小鼠急性肝损伤的保护作用及其机理

本研究将健康昆明种小鼠36只,雌雄各半,随机分为空白对照组、模型组、药物联苯组、伤寒头高剂量、中剂量及低剂量组。各分组连续给药3d,末次给药1h后,除正常对照组外,其余各组腹腔注射1%CCl4花生油溶液0.1mL/10g建立小鼠急性肝损伤模型。测试小鼠禁食24h后,摘眼球取血并处死动物,分离血清进行血清生化指标的测定,检测小鼠血清中门冬氨酸氨基转氨酶(AST)、丙氨酸氨基转氨酶(ALT)、白蛋白(ALB)和总蛋白(TP)水平;剖检并取肝脏组织测肝脏重量,取部分肝组织研磨成匀浆测定超氧化物歧化酶(SOD),丙二醛(MDA)和谷胱甘肽过氧化物酶(GSH-PX)。观察伤寒头处理下小鼠血清中AST、ALT、ALB和TP以及肝脏中SOD、MDA和GSH-PX的变化。结果表明,各伤寒头治疗组对AST、ALT均有明显的降低作用(P0.01),对TP、ALB没有影响(P0.05);各伤寒头治疗组对SOD和GSH-PX有升高作用(P0.05),对MDA有降低作用(P0.05),对肝脏指数没有影响(P0.05)。根据本研究结果,我们推断伤寒头对四氯化碳所致小鼠急性肝损伤具有明显的保护作用,主要是通过提高SOD和GSH-PX酶的活性,降低MDA来达到保护肝脏的作用。     

Thiol redox proteomics: Characterization of thiol-based post-translational modifications

Redox post-translational modifications on cysteine thiols (redox PTMs) have profound effects on protein structure and function, thus enabling regulation of various biological processes. Redox proteomics approaches aim to characterize the landscape of redox PTMs at the systems level. These approaches facilitate studies of condition-specific, dynamic processes implicating redox PTMs and have furthered our understanding of redox signaling and regulation. Mass spectrometry (MS) is a powerful tool for such analyses which has been demonstrated by significant advances in redox proteomics during the last decade. A group of well-established approaches involves the initial blocking of free thiols followed by selective reduction of oxidized PTMs and subsequent enrichment for downstream detection. Alternatively, novel chemoselective probe-based approaches have been developed for various redox PTMs. Direct detection of redox PTMs without any enrichment has also been demonstrated given the sensitivity of contemporary MS instruments. This review discusses the general principles behind different analytical strategies and covers recent advances in redox proteomics. Several applications of redox proteomics are also highlighted to illustrate how large-scale redox proteomics data can lead to novel biological insights.     

IQ67 DOMAIN protein 21 is critical for indentation formation in pavement cell morphogenesis

In plants, cortical microtubules anchor to the plasma membrane in arrays and play important roles in cell shape. However, the molecular mechanism of microtubule binding proteins, which connect the plasma membrane and cortical microtubules in cell morphology remains largely unknown. Here, we report that a plasma membrane and microtubule duallocalized IQ67 domain protein, IQD21, is critical for cotyledon pavement cell(PC) morphogenesis in Arabidopsis. iqd21 mutation caused increased indentation wi...     

Antibacterial activity of lyase-depolymerized products of alginate

A series of mannuronic acid (M-block) and guluronic acid (G-block) fractions (M1–M5 and G1–G5) with different molecular weights were obtained by lyase depolymerization of alginate and evaluated for in vitro antibacterial activity against 19 bacterial strains. The antibacterial data revealed that both types of fractions generally showed activity against certain tested bacteria, whereas M-block fractions showed broader spectra and more potent inhibition than G-block fractions. Among these fractions, M3 (molecular weight 4.235 kDa) exhibited the broadest spectrum of inhibition and high inhibitory activity against Escherichia coli (minimal inhibitory concentration, MIC = 0.312 μg mL⁻¹), Salmonella paratyphi B (MIC = 0.225 μg mL⁻¹), Staphylococcus aureus (MIC = 0.016 μg mL⁻¹) and Bacillus subtilis (MIC = 0.325 μg mL⁻¹).     

Production of a Highly Protease-Resistant Fungal α-Galactosidase in Transgenic Maize Seeds for Simplified Feed Processing

Raffinose-family oligosaccharide (RFO) in soybeans is one of the major anti-nutritional factors for poultry and livestocks. α-Galactosidase is commonly supplemented into the animal feed to hydrolyze α-1,6-galactosidic bonds on the RFOs. To simplify the feed processing, a protease-resistant α-galactosidase encoding gene from Gibberella sp. strain F75, aga-F75, was modified by codon optimization and heterologously expressed in the embryos of transgentic maize driven by the embryo-specific promoter ZM-leg1A. The progenies were produced by backcrossing with the commercial inbred variety Zheng58. PCR, southern blot and western blot analysis confirmed the stable integration and tissue specific expression of the modified gene, aga-F75m, in seeds over four generations. The expression level of Aga-F75M reached up to 10,000 units per kilogram of maize seeds. In comparison with its counterpart produced in Pichia pastoris strain GS115, maize seed-derived Aga-F75M showed a lower temperature optimum (50°C) and lower stability over alkaline pH range, but better thermal stability at 60°C to 70°C and resistance to feed pelleting inactivation (80°C). This is the first report of producing α-galactosidase in transgenic plant. The study offers an effective and economic approach for direct utilization of α-galactosidase-producing maize without any purification or supplementation procedures in the feed processing.     

Correlation between Serum Level of Monocyte Chemoattractant Protein-1 and Postoperative Recurrence of Spinal Tuberculosis in the Chinese Han Population

ObjectiveTo correlate serum level of monocyte chemoattractant protein-1 (MCP-1) with postoperative recurrence of spinal tuberculosis in the Chinese Han population.MethodsPatients of Han nationality with newly diagnosed spinal tuberculosis were consecutively included in this study. At different time points postoperatively, serum level of MCP-1 was determined using an enzyme linked immunosorbent assay. Recurrence of spinal tuberculosis after surgery and during the follow-up period was recorded. The correlation between serum MCP-1 level and recurrence of spinal tuberculosis was analyzed.ResultsA total of 169 patients with spinal tuberculosis were included in the study and followed up for an average of2.2±1.3 years (range, 1–5 years). Of these patients, 11 had postoperative recurrence of spinal tuberculosis. The patients’ serum level of MCP-1 increased significantly after postoperative recurrence of spinal tuberculosis. Once the symptoms of recurrence were cured, the serum level of MCP-1 decreased significantly and it did not differ from patients without disease recurrence.ConclusionPostoperative recurrence of spinal tuberculosis is likely to increase the serum level of MCP-1.