高浓度Cd,Pb污染水域中的微生物生态

用选择性培养基和滤纸片法研究了Cd、Pb污染水域中的微生物生态分布、对Cd、Pb的抗性及富集力。结果表明,污水中微生物量的变化与Cd、Pb浓度不相关。抗性微生物生物量受环境温度影响较大。微生物对Cd、Pb的抗性是霉菌>酵母和细菌,Pb>Cd。霉菌最高抗Cd、Pb浓度可达2×10~4mg·L~(-1)。酵母和细菌最高抗Cd浓度为5000mg·L~(-1)、Pb浓度为1×10~4mg·L~(-1),抗性微生物对Cd、Pb的富集力与其抗性及Cd、Pb的毒性密切相关。含Cd、Pb污水中的优势菌有欧文氏菌、产碱杆菌、节细菌、假丝酵母、曲霉和枝孢霉。     

蜘蛛杀虫肽基因的合成及其在植物中表达质粒的构建

近年来用生物制剂防治害虫,虽然可以避免环境污染,但效果往往不稳定,而用基因工程方法,将抗虫基因导入植物的基因组中,让植物自身产生抗虫物质,将是一种理想的途径［１,２］。抗虫的植物基因工程主要是利用苏云金杆菌的内毒素蛋白,转化此基因的烟草和番茄显示了对虫的抗性［３—６］。澳大利亚Ｄｅａｋｉｎ大学从一种蜘蛛毒液中分离纯化到一种只有３７个氨基酸的小肽,体外实验发现其能杀死多种对农业生产有害的昆虫,但对哺乳动物没有毒害作用［７］。我们根据此肽的氨基酸序列,采用植物偏爱的密码子,人工合成并克隆了此肽的基因…     

副溶血性弧菌免疫逃逸及其可能机制的研究进展

副溶血性弧菌是全球范围内威胁人体健康和食品安全的食源性致病菌。在感染人体的过程中,副溶血性弧菌通过将其效应蛋白直接注射至宿主细胞中操纵宿主,介导毒力的发挥,并进化出了一套完美的免疫逃逸策略,成功躲避免疫系统的攻击,引起急性肠胃炎、败血症和坏死性筋膜炎等疾病。副溶血性弧菌入侵上皮细胞,使胞内囊泡酸化,在与溶酶体融合之前逃逸到细胞质中,并且限制活性氧的产生,促进其在胞内生存。副溶血性弧菌可以诱导自噬,抑制NLRC4炎症小体介导的caspase-1的激活,还可以通过抑制TAK1激酶,阻止MAPK和NF-κB信号通路的激活,干扰免疫系统激活,借助多种手段共同协作从而达到免疫逃逸。本文系统总结了副溶血性弧菌现已研究的免疫逃逸机制,并对其可能存在的免疫逃逸机制提供了新的见解和方向,对深入了解副溶血性弧菌的致病机理和防控药物靶向位点的选择及研发具有重要意义。     

汽车碰撞中的人体动力学仿真

将多则体系统动力学中的Ｌ－Ｅ法与经典碰撞理论相结合,推导了树形系统下的Ｌ－Ｅ碰撞动力学方程,并运用面向对象的编程方法开发出汽车碰撞中人体动力学仿真软件,成功地仿真出汽车碰撞后人体运动响应．     

电场对完整青蛙横纹肌收缩机理的椭圆偏振法研究

利用能反映肌纤维内部结构的椭圆偏振参数研究恒定电场,脉冲电场对完整的青蛙横纹肌收缩的影响,研究表明,电场对肌纤维作用后,肌质网释放钙离子,致使肌纤维中蛋白质分子运动后出现收缩效应。实验发现：椭圆偏参数的测量灵敏度和肌小节长度有关,蛋白质运动规律和电场的性质的关系无的差异,只有量的不同。它们的共同特点是,随着电场强度的逐渐增强,其退偏率的变化呈先下降一上升的凹形曲线,这是由于电场引起的肌球蛋白分子极     

Comparative Structural and Functional Characterization of Sorghum and Maize Duplications Containing Orthologous Myb Transcription Regulators of 3-Deoxyflavonoid Biosynthesis

Sequence characterization of the genomic region of sorghum yellow seed 1 shows the presence of two genes that are arranged in a head to tail orientation. The two duplicated gene copies, y1 and y2 are separated by a 9.084 kbp intergenic region, which is largely composed of highly repetitive sequences. The y1 is the functional copy, while the y2 may represent a pseudogene; there are several sequence indels and rearrangements within the putative coding region of y2. The y1 gene encodes a R2R3 type of Myb domain protein that regulates the expression of chalcone synthase, chalcone isomerase and dihydroflavonol reductase genes required for the biosynthesis of 3-deoxyflavonoids. Expression of y1 can be observed throughout the plant and it represents a combination of expression patterns produced by different alleles of the maize p1. Comparative sequence analysis within the coding regions and flanking sequences of y1, y2 and their maize and teosinte orthologs show local rearrangements and insertions that may have created modified regulatory regions. These micro-colinearity modifications possibly are responsible for differential patterns of expression in maize and sorghum floral and vegetative tissues. Phylogenetic analysis indicates that sorghum y1 and y2 sequences may have arisen by gene duplication mechanisms and represent an evolutionarily parallel event to the duplication of maize p2 and p1 genes.     

水圈微生物专栏序言

<正>国家自然科学基金委员会于2017年启动了“水圈微生物驱动地球元素循环的机制”重大研究计划(简称“水圈微生物”计划)。“水圈微生物”计划聚焦典型水圈生境,通过多学科交叉研究,借助新技术、新方法,揭示水圈微生物在物种、群落和生态水平驱动碳氮硫循环的机制及其环境响应,认识水圈微生物在元素地球生物化学循环中的宏观生态作用,为应对全球变化、保护水圈生态服务功能、实施双碳战略、     

昆虫杆状病毒表达系统表达人载脂蛋白A-Ⅰ

载脂蛋白apoA-Ⅰ是高密度脂蛋白中最主要的蛋白,在胆固醇代谢及动脉粥样硬化等疾病的发生和控制中有重要作用。为了建立大量生产和制备该蛋白的方法,昆虫杆状病毒表达系统被用来高效表达了两种形式的人apoA-Ⅰ。不带有信号肽序列的proapoA-Ⅰ蛋白表达后主要在细胞内,但在感染的晚期也有相当量的重组蛋白进入细胞培养液中。用蛇磷脂酶A2抑制因子α亚基信号肽序列引导表达的apoA-Ⅰ蛋白在感染早期可以被分泌到培养液中。在此基础上,通过Phenyl Sepharose疏水柱层析,从感染细胞的培养液中初步分离纯化了成熟的apoA-Ⅰ蛋白。这一结果为apoA-Ⅰ的进一步研究和应用奠定了基础。     

Molecular genetic characterization of rice seed lipoxygenase 3 and assessment of its effects on seed longevity

Lipoxygenases (LOXs) are enzymes involved in lipid peroxidation. Here we reported the identification, molecular and functional characterization of the gene encoding rice (Oryza sativa L.) seed LOX3 (sLOX3). Via a map-based cloning strategy we identified Os03g0700400 as the candidate gene encoding sLOX3. Further functional complementary test and biochemical characterization of the recombinant Os03g0700400 protein verified the identification. The sLOX3 gene was highly expressed in roots, moderately in embryos and very weakly in leaves, leaf sheaths and stems. Transient expression experiment (in rice protoplasts) and subsequent laser confocal microscopic analysis demonstrated that the sLOX3 protein was localized into the cytosol. We next showed that overexpression of sLOX3 in a japonica sLOX3-normal rice cultivar, Wuyunjing 7 accelerated the decrease of seed germination ability when the seeds were routinely stored, which demonstrated that sLOX3 had a negative effect on seed longevity (storability). Meanwhile, an increased occurrence of embryo decay was observed in the same transgenic seeds, suggesting that sLOX3 might negatively affect seed longevity by facilitating colonization of particular seed pathogens. Our result forwarded the understanding of the effects of 9-LOX on rice seed longevity.