Purification, Biological Activities, and Molecular Cloning of a Novel Mannose-Binding Lectin from Bulbs of Zephyranthes candida Herb （Amaryllidaceae）

A novel mannose-bindlng aggiutinln was purified from bulbs of Zephyranthes candida Herb by extraction, precipitation with 80% （NH4）2SO4, and ion-exchange chromatography on DEAE-Sepharose followed by gel flitration on Sephscryl S-100. The purified Z. candida agglutlnln （ZCA） migrated as a single band of 12 kDa on sodium dodecyi suifate-poiyecryiamide gel electrophoresis under reducing and non-reducing conditions. The apparent molecular mass of the iectln, as datermlned by gel filtration chromatography, was 48 kDa. The results Indicated that ZCA was composed of four Identical subunlts of 12 kDa each （homotetramerlc nature）. The ZCA agglutlhated rabbit erythrocytes, Escherichla coil and Saccharomyces cerevislae ceils at concentrations of 0.95, 1.90, and 31.30 μg/mL, respectively. Bloassays Indicated that ZCA has a significant effect on wheat aphid survival. Mortality after 7 d was 〉 90% at 0.26%. A degenerate primer was designed In accordance with the N-terminal partial sequence of purified ZCA. The full-length cDNA was cloned by 3＇- and 5＇-rapid amplification of cDNA ends. The full-length cDNA had 661 bp and the sequence encoded an open reading frame of 168 amino acids. The mature protein of ZCA Includes 109 amino acid residues and the molecular weight of the protein was 12.1 kDa. The result show that the zca gene encodes a protein precursor with a signal peptlde, a mature protein, and a C-terminal cleavage amino acids sequence. Molecular modeling of ZCA Indicated that Its three-dimensional atructure strongly resembies that of the snowdrop aggiutinin. Blocks＇ analysis revealed that the deduced amino acid sequence of ZCA has three functional domains specific for agglutination and three carbohydrate binding boxes （QDNY）.     

蛋白质组学研究揭示的甘蓝型油菜非生物胁迫应答机制

油菜(Brassica napus L.)是我国的主要油料作物之一,在生长发育过程中经常受到干旱、高温、高盐和营养缺乏等非生物胁迫。这些胁迫通常会阻碍油菜的生长发育,导致品质和产量下降。近年来,快速发展的高通量蛋白质组学技术为揭示油菜胁迫响应分子机制提供了新线索。本文综合分析了油菜不同组织/器官(如:叶片、根、下胚轴和种子)在响应盐、高温、干旱、草酸和缺素(磷、硫和硼)等逆境过程中675种蛋白质的丰度变化特征,揭示了其胁迫应答机制,主要包括:(1)通过G蛋白介导的信号通路感知与传递胁迫信号;(2)通过改变参与糖类与能量代谢相关酶的丰度调节代谢水平;(3)通过叶绿素合成的变化调节光合作用;(4)调节转录因子、蛋白质合成与命运相关蛋白质的丰度,从而在转录、翻译以及翻译后修饰等水平上应答逆境;(5)通过调节膜联蛋白、V型H+-ATP酶等质膜蛋白质,促进细胞内物质吸收与转运;(6)通过细胞骨架动态重塑保持正常细胞结构;(7)利用调节抗氧化酶系统清除活性氧,并通过合成多种防御物质减轻细胞受到的伤害。本综述为解析油菜逆境应答网络体系中的关键调控及代谢通路的变化提供了重要信息。     

AGEs Induce Cell Death via Oxidative and Endoplasmic Reticulum Stresses in Both Human SH-SY5Y Neuroblastoma Cells and Rat Cortical Neurons

Advanced glycation endproducts (AGEs) are elevated in aging and neurodegenerative diseases such as Alzheimer??s disease (AD), and they can stimulate the generation of reactive oxygen species (ROSs) via NADPH oxidase, induce oxidative stress that lead to cell death. In the current study, we investigated the molecular events underlying the process that AGEs induce cell death in SH-SY5Y cells and rat cortical neurons. We found: (1) AGEs increase intracellular ROSs; (2) AGEs cause cell death after ROSs increase; (3) oxidative stress-induced cell death is inhibited via the blockage of AGEs receptor (RAGE), the down-regulation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, and the increase of scavenging by anti-oxidant alpha-lipoic acid (ALA); (4) endoplasmic reticulum (ER) stress was triggered by AGE-induced oxidative stress, resulting in the activation of C/EBP homologous protein (CHOP) and caspase-12 that consequently initiates cell death, taurine-conjugated ursodeoxycholic acid (TUDCA) inhibited AGE-induced ER stress and cell death. Blocking RAGE?CNADPH oxidase, and RAGE?CNADPH oxidase?CROSs and ER stress scavenging pathways could efficiently prevent the oxidative and ER stresses, and consequently inhibited cell death. Our results suggest a new prevention and or therapeutic approach in AGE-induced cell death.     

Effect of amino acid residue and oligosaccharide chain chemical modifications on spectral and hemagglutinating activity of Millettia dielsiana Harms. ex Diels. lectin

The effects of modifying the carbohydrate chain and amino acids on the conformation and activity of Millettia dielsiana Harms. ex Diels. lectin (MDL) were studied by hemagglutination, fluorescence and circular dichroism analysis. The modification of tryptophan residues led to a compete loss of hemagglutinating activity; however, the addition of mannose was able to prevent this loss of activity. The results indicate that two tryptophan residues are involved in the carbohydrate-binding site. Modifications of the carboxyl group residues produced an 80% loss of activity, but the presence of mannose protected against the modification. The results suggest that the carboxyl groups of aspartic and glutamic acids are involved in the carbohydrate-binding site of the lectin. However, oxidation of the carbohydrate chain and modification of the histidine and arginine residues did not affect the hemagglutinating activity of MDL. Fluorescence studies of MDL indicate that tryptophan residues are present in a relatively hydrophobic region, and the binding of mannose to MDL could quench tryptophan fluorescence without any change in λmax. The circular dichroism spectrum showed that all of these modifications affected the conformation of the MDL molecule to different extents, except the modification of arginine residues. Fluorescence quenching showed that acrylamide and iodoacetic acids are able to quench 77% and 98% of the fluorescence of tryptophan in MDL, respectively. However, KI produced a barely perceptible effect on the fluorescence of MDL, even when the concentration of I^- was 0.15M. This demonstrates that most of tryptophan residues are located in relatively hydrophobic or negatively charged areas near the surface of the MDL molecule.     

一种新的甘露糖结合凝集素--朱顶兰凝集素基因的克隆及序列分析

运用同源克隆的方法设计简并引物,通过3′和5′RACE技术,从石蒜科植物朱顶兰(Amaryllis vittata Ait)总RNA中克隆了编码此凝集素(AVA)的全长cDNA序列.该基因全长686 bp,起始密码子位于第41～43 bp,终止密码子位于515～517 bp处,开放阅读框长474 bp,编码158个氨基酸,包含信号肽序列、成熟蛋白序列和C-末端剪切序列的前体蛋白.成熟蛋白由109个氨基酸残基组成,分子量为11.9kD.成熟蛋白在氨基酸水平上与雪花莲凝集素、水仙凝集素、石蒜凝集素和君子兰凝集素分别有73.4%、85.3%、80.7%和83.5%的同源性;朱顶兰凝集素的分子模式显示其与雪花莲凝集素有极其相似的三维结构;在Blocks数据库中检索AVA蛋白氨基酸序列的结构域,发现有3个凝集素功能结构域,并具有3个典型的甘露糖专一结合位点盒(QDNY).     

Role and mechanism of neural stem cells of the subventricular zone in glioblastoma

Glioblastoma multiforme (GBM), the most frequently occurring malignant brain tumor in adults, remains mostly untreatable. Because of the heterogeneity of invasive gliomas and drug resistance associated with the tumor microenvironment, the prognosis is poor, and the survival rate of patients is low. Communication between GBMs and non-glioma cells in the tumor microenvironment plays a vital role in tumor growth and recurrence. Emerging data have suggested that neural stem cells (NSCs) in the subventricular zone (SVZ) are the cells-of-origin of gliomas, and SVZ NSC involvement is associated with the progression and recurrence of GBM. This review highlights the interaction between SVZ NSCs and gliomas, summarizes current findings on the crosstalk between gliomas and other non-glioma cells, and describes the links between SVZ NSCs and gliomas. We also discuss the role and mechanism of SVZ NSCs in glioblastoma, as well as the interventions targeting the SVZ and their therapeutic implications in glioblastoma. Taken together, understanding the biological mechanism of glioma-NSC interactions can lead to new therapeutic strategies for GBM.     

基于SNP分子标记的凹叶木兰遗传多样性初步研究

凹叶木兰是我国特有的木兰属植物,仅分布于我国四川和云南两省相邻地区,目前已被列入中国物种红皮书名录,属易危物种。该研究以采自四川南部麻咪泽和美姑大风顶两个自然保护区的野生凹叶木兰为材料,利用以PCR和测序为基础的SNP分子标记方法,初步研究了凹叶木兰的遗传多样性。结果表明:在扩增出的4条510bp长的序列上,平均在73bp左右的序列长度上能够检测到一个SNP位点,说明两个自然保护区内不同居群的凹叶木兰具有较高遗传多样性;序列间相似度达97%,与引物所对原序列相似度达36%,表明该序列适宜进行凹叶木兰遗传多样性研究。研究结果为进一步开展凹叶木兰遗传多样性的研究及其保护政策的制定提供了参考。     

一种新的甘露糖结合凝集素——朱顶兰凝集素基因的克隆及序列分析

运用同源克隆的方法设计简并引物,通过3′和5′RACE技术,从石蒜科植物朱顶兰(Amaryllis vittata Ait)总RNA中克隆了编码此凝集素(AVA)的全长cDNA序列。该基因全长686 bp,起始密码子位于第41～43 bp,终止密码子位于515～517bp处,开放阅读框长474 bp,编码158个氨基酸,包含信号肽序列、成熟蛋白序列和C-末端剪切序列的前体蛋白。成熟蛋白由109个氨基酸残基组成,分子量为11.9kD。成熟蛋白在氨基酸水平上与雪花莲凝集素、水仙凝集素、石蒜凝集素和君子兰凝集素分别有73.4％、85.3％、80.7％和83.5％的同源性;朱顶兰凝集素的分子模式显示其与雪花莲凝集素有极其相似的三维结构;在Blocks数据库中检索AVA蛋白氨基酸序列的结构域,发现有3个凝集素功能结构域,并具有3个典型的甘露糖专一结合位点盒(QDNY)。     

体能相关基因研究的新进展

近年来体能与基因的关系又成为一个热点话题,人类遗传学的研究证实 ,人类体能的差异有遗传基础。 2000年以来,有关体能分子遗传学的研究飞速发展,发表的文章数及报道的相关基因座超过过去几年的总量,已经报到了70多个关注的基因座,证明基因与VO_2MAX、肌肉力量和乳酸阈值等有关。我国航空航天事业和载人航天器的开发、国防建设的需求等都提示,今后特殊体能人才的基因选材将不容忽视。对于具有特殊体能的个体进行科学选材,可以提高针对性和降低后期培养的资金浪费。同样,对于早期发现和培养具备体育运动天赋的人才将是经济快速和实用的方法。体能相关基因的研究还将为揭示这些基因座的功能、促进健康事业起重要作用。通过对国际已报道的主要与有氧运动相关的基因座和试验结果进行综述,为我国尽早开展相关研究提供基础信息。