Cell surface engineering by a modified Staudinger reaction

Selective chemical reactions enacted within a cellular environment can be powerful tools for elucidating biological processes or engineering novel interactions. A chemical transformation that permits the selective formation of covalent adducts among richly functionalized biopolymers within a cellular context is presented. A ligation modeled after the Staudinger reaction forms an amide bond by coupling of an azide and a specifically engineered triarylphosphine. Both reactive partners are abiotic and chemically orthogonal to native cellular components. Azides installed within cell surface glycoconjugates by metabolism of a synthetic azidosugar were reacted with a biotinylated triarylphosphine to produce stable cell-surface adducts. The tremendous selectivity of the transformation should permit its execution within a cell's interior, offering new possibilities for probing intracellular interactions.     

无硫复合护色剂处理的干制苹果片中差异蛋白表达的分析

[目的]分析经无硫复合护色剂处理的苹果片在干制后差异蛋白的表达情况。[方法]采用无标记(Label-free)定量蛋白质组学技术对复合护色剂处理的干制苹果片进行蛋白质组学研究,探讨蛋白质组表达水平的差异。所提取的蛋白质样品经酶解、色谱质谱检测分析,用Label-free定性定量软件maxquant(1.5.0.12)结合搜库定性软件Andromeda,对每个样本进行定性定量,通过蛋白质相对定量的比较寻找差异表达蛋白。[结果]与非处理苹果片相比,差异蛋白总数为909个,上调差异蛋白质319个,下调差异蛋白质590个;生物学过程主要集中在代谢过程、细胞过程。分子功能主要在绑定、催化活性、能量代谢等部分。细胞组件主要集中在细胞膜相关的部件。[结论]该研究可为解析复合护色剂处理后干制苹果片中次生代谢物差异的成因及其抑制褐变的蛋白质机制提供参考。     

四氯虫酰胺对棉铃虫生物活性的温度效应及其解毒酶相关机制

【目的】研究四氯虫酰胺对棉铃虫生物活性的温度效应及其影响程度,分析棉铃虫体内4种解毒酶系对该温度效应的影响机制。【方法】采用浸叶法,分别测定15、20、25、30和35℃条件下,四氯虫酰胺对棉铃虫的室内生物活性,测定四氯虫酰胺亚致死剂量下,棉铃虫体内羧酸酯酶(CarE)、谷胱甘肽S-转移酶(GST)、多功能氧化酶(MFO)和尿苷二磷酸糖基转移酶(UGT)比活力的变化。【结果】四氯虫酰胺对棉铃虫的生物活性具有明显的正温度效应,与15℃时相比,其温度系数从+5.52增长为+1 257.35。四氯虫酰胺对棉铃虫的正温度效应可能与GST和MFO有关,其中GST在较低温下的活性变化尤为显著,而CarE和UGT则未发现与四氯虫酰胺生物活性的正温度效应明显相关。【结论】四氯虫酰胺对棉铃虫表现为明显的正温度系数药剂,高温时使用生物活性最佳,低温时抑制GST活性,可能会提高四氯虫酰胺对棉铃虫的生物活性。     

Microinjected c-myc as a competence factor

While a number of oncogenes are expressed in a cell cycle-dependent manner, their role in the control of cell proliferation can only be established by a direct functional assay. The c-myc protein, upon microinjection into nuclei of quiescent Swiss 3T3 cells, cooperated with platelet-poor plasma in the stimulation of cellular DNA synthesis. This suggests that c-myc protein, like platelet-derived growth factor (PDGF), may act as a competence factor in the cell cycle to promote the progression of cells to S phase. The presence in the medium of an antibody against PDGF abolished DNA synthesis induced by microinjected PDGF; however, the microinjected c-myc protein stimulated DNA synthesis even when its own antibody was present in the medium. The c-myc protein may act as an intracellular competence factor, while PDGF expresses its biological activity only from outside the cells.     

枯草芽孢杆菌NCD-2对棉花根系分泌物L-脯氨酸响应的转录-蛋白质组学联合分析

【目的】棉花根系分泌物L-脯氨酸是影响生防菌株定殖的关键因素之一,前期研究发现L-脯氨酸能够提高枯草芽孢杆菌（Bacillus subtilis）NCD-2生物膜形成能力。通过高通量测序技术分析L-脯氨酸调控枯草芽孢杆菌NCD-2生物膜形成和生防潜力相关的基因,为深入认识棉花根系分泌物与生防菌株的分子互作关系打下基础。【方法】以枯草芽孢杆菌NCD-2菌株为供试材料,外源添加浓度为10 mg·mL^-1的L-脯氨酸共培养24 h后,分别进行转录组（RNA-seq）和同位素标记相对定量蛋白质组技术（iTRAQ）分析,对所获得的转录组和蛋白质组数据进行生物信息学分析,利用实时荧光定量PCR（RT-qPCR）验证不同代谢通路中部分差异基因的表达情况。 【结果】转录组分析发现,L-脯氨酸和NCD-2菌株共培养后,获得1 071个差异表达基因（DEG）,其中602个基因上调,469个基因下调。GO分析发现在生物过程、细胞组分和分子功能方面分别有49、14和30个功能条目显著富集。KEGG代谢通路主要富集在化合物代谢、鞭毛组装、细菌运动和趋化作用。蛋白质组学分析发现,筛选到211个差异表达蛋白（DEP）,其中118个蛋白上调,93个蛋白下调。GO分析发现在生物过程和分子功能方面分别有13和8个功能条目显著富集。KEGG代谢通路主要富集在氨基酸代谢、碳水化合物类代谢、鞭毛组装和ABC转运蛋白。进一步转录-蛋白质组学联合分析发现,在L-脯氨酸作用下,检测到共有的显著差异表达基因（或蛋白）112个,其中38个基因（或蛋白）下调,74个基因（或蛋白）上调。GO功能显著富集主要集中在营养库活性、催化活性、细胞膜、定位、细胞脂质代谢过程、氧化还原过程、sigma因子活性、转运活性、芽孢形成9个方面。KEGG代谢通路主要富集在能量代谢、ABC转运蛋白、抗生素生物合成、鞭毛组装、运动或趋化作用和双组分系统方面。RT­qPCR验证了26个差异表达显著基因,结果发现在表达量上存在一定的差异,但表达趋势与RNA­seq和iTRAQ组学分析结果基本一致。【结论】棉花根系分泌物L-脯氨酸与枯草芽孢杆菌NCD-2之间的互作存在一个复杂的生物过程,依赖于不同代谢通路网络中的多个基因。双组分系统、抗生素生物合成、能量代谢、运动或趋化作用、鞭毛组装和ABC转运蛋白通路中的差异基因（或蛋白）可能在棉花根系分泌物与枯草芽孢杆菌互作过程方面发挥着重要作用。     

枯草芽孢杆菌G87抗菌蛋白对稻瘟病菌和稻恶苗病菌的抑制作用

为明确枯草芽孢杆菌(Bacillus subtilis)G87抗菌蛋白的生物活性,采用菌丝生长、分生孢子萌发和芽管伸长抑制的方法,研究其对稻瘟病菌(Magnaporthe grisea)和稻恶苗病菌(Gibberella fujikuroi)的抑制作用。结果表明:抗菌蛋白能明显抑制2种病菌菌丝生长、分生孢子萌发和芽管伸长。1.20mg·mL-1抗菌蛋白对稻瘟病菌菌落直径和菌丝干重的抑制率分别达60%和80%以上;2.40mg·mL-1抗菌蛋白对稻恶苗病菌分生孢子萌发和芽管伸长的抑制率均达60%以上。抗菌蛋白还能显著破坏2种病菌菌丝形态,使菌丝细胞畸形膨大、原生质浓缩和外渗、细胞壁破损以及菌体崩溃等。因此,枯草芽孢杆菌G87抗菌蛋白具有重要的抗菌生物活性。     

Sickle-cell trait in human biological and cultural evolution. Development of agriculture causing increased malaria is bound to gene-pool changes causing malaria reduction

The particular agricultural adaptation we have been considering is the ultimate determinant of the presence of malaria parasites in the intracellular environment of the human red blood cell. This change in the cellular environment is deleterious for normal individuals, but individuals with the sickle-cell gene are capable of changing their red-cell environment so that intense parasitism never develops. Normal individuals suffer higher mortality rates and lower fertility rates in a malarious environment than individuals with the sickle-cell trait do, so the latter contribute proportionately more people to succeeding generations.     

2 种原代培养方法对新生大鼠大脑皮质神经元生物学特性的影响

为明确不同培养方法对新生大鼠大脑皮质神经元成熟时间、形态特征、纯度及活力等生物学特性的影响,采用DMEM培养基加Neurobasal无血清培养基法或Neurobasal无血清培养基法原代培养新生24h内SD大鼠大脑皮质神经元,倒置显微镜下观察细胞形态,MTT法检测细胞活力,免疫荧光细胞化学染色法检测神经元纯度及活性.结果显示,2种方法培养的神经元形态差异无统计学意义;但与DMEM培养基加Neurobasal无血清培养基法相比,Neurobasal无血清培养基法培养的神经元成熟更早,数目更多,纯度更高,活力更强(p0.05).结果提示,原代培养的大脑皮质神经元部分生物学特性受培养方法直接影响;Neurobasal无血清培养基法所得神经元纯度与活性较高,这为实验目的导向的神经元原代培养方法选择提供了借鉴.     

基于ATM网络路由选择对多国协作解决“完美风暴”问题的研究

根据约翰.贝丁顿关于＂完美风暴＂的理论,提出了2个全新的概念：气候因子与＂完美风暴＂发生率。对全球以及主要国家进行相关气候因子与＂完美风暴＂发生率的量化分析,并借助ATM网络的路由选择对多国协作解决＂完美风暴＂的最优效果进行有效的预测。模拟的结果表明：参与协作的国家越多,＂完美风暴＂的发生率越低。当世界有20个国家共同面对危机问题时,可有效地将＂完美风暴＂发生率降低至0.34。     

细胞和个体水平沉默效应的差异

[目的]研究3种不同长度的四联shRNA载体及其在细胞与个体水平的沉默效应差异。[方法]以EGFP为靶标基因,用hU6、mU6、h7SK、hH1 4种启动子,构建21、27、29 bp的3种四联沉默载体,通过转染Vero细胞和注射小鼠肌肉,以实时荧光定量PCR的方法检测绿色荧光蛋白基因的mRNA水平。[结果]3种载体都有很强的沉默效应,其在细胞水平上的沉默效应远高于个体水平上,可以通过未成年鼠的肌肉注射进行转基因。[结论]多位点串联表达shRNA是一种可以达到较好干扰效果的方法,肌肉注射将是一个简便的转基因途径。     

A synthetic peptide from fibronectin inhibits experimental metastasis of murine melanoma cells

Adhesive interactions between cells and the extracellular matrix occur at several stages of metastasis. Such interactions might be inhibited by synthetic peptide probes derived from the cell-binding regions of matrix molecules. Gly-Arg-Gly-Asp-Ser (GRGDS) is a pentapeptide sequence that appears to be critical for cell interaction with fibronectin. Coinjection of GRGDS with B16-F10 murine melanoma cells dramatically inhibited the formation of lung colonies in C57BL/6 mice. Two closely related control peptides, in which specific amino acids within the GRGDS sequence were transposed or substituted, displayed little or no activity. Inhibition by GRGDS was dose-dependent, noncytotoxic, and did not result from an impairment of cellular tumorigenicity. GRGDS may function by inhibiting tumor cell retention in the lung since radiolabeled B16-F10 tumor cells injected with the peptide were lost at a substantially greater rate than control cells.     

A cytoplasmic protein inhibits the GTPase activity of H-Ras in a phospholipid-dependent manner

A cytoplasmic protein has been identified that inhibits the guanosine triphosphatase (GTPase) activity of bacterially synthesized, cellular H-Ras protein. This GTPase inhibiting protein is able to counteract the activity of GTPase activating protein (GAP), which has been postulated to function as a negative regulator of Ras activity. The potential biological importance of the GTPase inhibiting protein is further supported by its interaction with lipids. Phospholipids produced in cells as a consequence of mitogenic stimulation increase the activity of the GTPase inhibiting protein, as well as inhibit the activity of GAP. The interaction of such lipids with each of these two regulatory proteins would, therefore, tend to increase the biological activity of Ras and stimulate cell proliferation.     

Kinetic characterization of ribonuclease-resistant 2'-modified hammerhead ribozymes

The incorporation of 2'-fluoro- and 2'-aminonucleotides into a hammerhead ribozyme was accomplished by automated chemical synthesis. The presence of 2'-fluorouridines, 2'-fluorocytidines, or 2'-aminouridines did not appreciably decrease catalytic efficiency. Incorporation of 2'-aminocytidines decreased ribozyme activity approximately by a factor of 20. The replacement of all adenosines with 2'-fluoroadenosines abolished catalysis in the presence of MgCl2 within the limits of detection, but some activity was retained in the presence of MnCl2. This effect on catalysis was localized to a specific group of adenines within the conserved single-stranded region of the ribozyme. The decrease in catalytic efficiency was caused by a decrease in the rate constant; the Michaelis constant was unaltered. The 2'-fluoro and 2'-amino modifications conferred resistance toward ribonuclease degradation. Ribozymes containing 2'-fluoro- or 2'-aminonucleotides at all uridine and cytidine positions were stabilized against degradation in rabbit serum by a factor of at least 10(3) compared to unmodified ribozyme.     

‘仓方早生’桃及其早熟芽变不同发育时期果实的转录组分析

【目的】通过对桃品种‘仓方早生’及其早熟芽变不同发育时期的果实进行转录组分析，挖掘参与调控桃果实成熟的关键因子，为深入研究桃果实成熟调控机理提供理论依据。【方法】以桃品种‘仓方早生’及其早熟芽变为试材，每个品种分别选择长势一致的样品树5株，分别于花后30 d（对应‘仓方早生’c1、早熟芽变y1）、45 d（对应c2、y2）、59 d（对应c3、y3）、71 d（对应c4、y4）及89 d（对应c5）对不同发育时期的桃去皮果肉进行取样和转录组测序，并利用实时荧光定量PCR(qRT-PCR)对筛选的差异表达基因进行定量验证；利用GO和KEGG对‘仓方早生’及其早熟芽变的差异表达基因进行分析；基于差异表达基因构建加权基因共表达网络分析（weighted gene co-expression network analysis,WGCNA），从中鉴定出与果实成熟密切相关的枢纽模块和枢纽基因。【结果】将处于果实相同发育时期的转录组数据进行比较，得到y1与c1、y2与c2、y3与c4和y4与c5四组对比数据，共筛选出差异表达基因4 395个，其中上调表达基因2 212个，下调表达基因2 183个。其...     

Radiosensitivity and rate of cell division: "law of Bergonié and Tribondeau"

The rate of cell division decreases as tobacco leaves grow, and older leaves grow without any cell divisions. Disks were cut from leaves having differing degrees of cell division at various developmental stages. In the chlorenchy, induced susceptibility to photodestruction of chloroplasts was used to measure sensitivity to gamma radiation as a function of the rate of cell division. The same biological effect can thereby be studied both in dividing and in nondividing tissues of the same morphological and physiological cell types. The radiosensitivities were approximately the same, irrespective of the extent of cell divisions.     

Imidazole: fungitoxic derivatives

Study of several new types of fungitoxic derivatives of imidazole reveals that imidazoles substituted on the imine nitrogen atom are likely to be active if the substituent is electron-attracting, and if the atom connecting it to the imidazolyl moiety has tetrahedral geometry. Fungitoxicity is high with phosphinamidothionate and triarylmethyl groups as substituents. The presence of an asymmetric phosphorus atom in the substituent has no effect on fungitoxicity, but affects mammalian toxicity.     

Modeling the heart--from genes to cells to the whole organ

Successful physiological analysis requires an understanding of the functional interactions between the key components of cells, organs, and systems, as well as how these interactions change in disease states. This information resides neither in the genome nor even in the individual proteins that genes code for. It lies at the level of protein interactions within the context of subcellular, cellular, tissue, organ, and system structures. There is therefore no alternative to copying nature and computing these interactions to determine the logic of healthy and diseased states. The rapid growth in biological databases; models of cells, tissues, and organs; and the development of powerful computing hardware and algorithms have made it possible to explore functionality in a quantitative manner all the way from the level of genes to the physiological function of whole organs and regulatory systems. This review illustrates this development in the case of the heart. Systems physiology of the 21st century is set to become highly quantitative and, therefore, one of the most computer-intensive disciplines.     

Effect of rare earth application on the growth of Trichoderma spp. and several plant pathogenic fungi

Rare earth elements (REEs) enriched fertilisers are currently used in China for soil and foliar applications to crops, but little is known about the effect of REEs applications on the growth of beneficial and detrimental soilborne microorganisms. The growth of biological control agents Trichoderma atroviride strain P1, Trichoderma harzianum strain A6 and strain T22, plant pathogens Botrytis cinerea, Alternaria alternata, Fusarium solani, Rhizoctonia solani and Sclerotinia scleroti…     

Quantifying the information content of lattice images

Quantitative information may be extracted from local areas of images that consist of one or more types of unit cell. Fourier-space analysis, real-space intensity analysis, and real-space vector pattern recognition are discussed. The pattern recognition approach efficiently exploits the available information by representing the intensity distribution within each unit cell of the image as a multidimensional vector. Thus, the amount and the effect of noise present are determined, statistically significant features are identified, and quantitative comparisons are made with model images. In the case of chemical lattice images, the position of a vector can be directly related to the atomic composition of the unit cell it represents, allowing quantitative chemical mapping of materials at near-atomic sensitivity and resolution. More generally, the vector approach allows the efficient and quantitative extraction of information from images, which consist of mosaics of unit cells.