阿扎霉素B(Azalomycin B)研究进展

介绍阿扎霉素B的生物学来源,研究历史,主要理化性质和结构确定,同时阐述了阿扎霉素B的生物合成途径,构效关系,生物学特性和应用前景。     

B.B.Brodie(1907～1989)

B.B.Brodie博土,一个先驱药理学家和美国国家科学院院士,1989年2月28日逝世。生前是美国国立卫生研究院心脏研究所化学药理实验室的创始人和第一任主任。     

Bücherbesprechung (Book Reviews)

Abstract

A field experiment was conducted during 2002 – 2003 and 2003 – 2004 to study the impact of controlling the insect vector, Whitefly, of yellow mosaic virus on the performance of green gram grown under rainfed lowland rice fallow situation. Insecticide, Imidachloprid 12.5 kg a.i./ha, was applied at 15- and 30-days growth to four green gram varieties, direct-sown under residual soil moisture conditions after the harvest of kharif rice. Results showed crops under YMV-management achieved 65.67% more seed yield producing 11.68 q/ha, which was significantly higher than the crops under no YMV management (7.05 q ha^?1). Plants which had been treated with insecticide were found to be less affected (8.50%) by YMV compared to those which had no treatment (20.10%). Varieties PDM 54 and PDM 11 emerged as superior, producing significantly higher seed yields, 12.73 and 11.69 q/ha respectively; while Pusa vishal (8.21 q ha^?1) and Pusa 105 (7.85 q ha^?1) produced moderately compared with the local variety (6.31 q ha^?1). In addition, PDM 54 and PDM 11 showed relatively more resistance against YMV infestation recording 5.23% and 6.01% infected plants.     

恐龙遗址旅游指南(3)欧洲篇(中B)

第三站:英国西德纳姆镇(Sydenhm)水晶宫公园(Crystal Palace Park) 离开刘易斯镇,我们原路返回伦敦市,继续这次朝圣之旅.我们先到著名的伦敦桥南端的伦敦桥站火车站(London Bridge),这个车站于1836年12月开始运营,以连结东南郊的通勤及短程列车为主,因此车站的早晚高峰时间极为拥挤混杂.     

Total synthesis of (±)-elegansidiol, (±)-farnesiferol B,and (±)-farnesiferol D

The racemic total synthesis of elegansidiol, farnesiferol B, and farnesiferol D has been obtained following a Diels–Alder approach. Gillman addition, cross metathesis reaction are the other key steps involved in the target synthesis.     

提高枯草杆菌(B.subtilis)原生质体再生率的研究(简报)

细菌原生质体制备和再生是研究细胞融合的前提条件,但关于其原生质体形成及再生的最适条件迄今尚缺乏系统的研究。再生率不高,且不稳定。本文研究了有关诸因素对供试菌株原生质体化及其活性的影响,尤其是提高再生率的措施。试验所用材料,菌株B.Subtilis Ki-2-132(Thr~-,Val~-,Ile~-,Str~+)由中国科学院遗传所赠送;溶菌酶由汉口蛋厂1981     

Thioredoxin-mediated Denitrosylation Regulates Cytokine-induced Nuclear Factor κB (NF-κB) Activation

S-nitrosylation of nuclear factor κB (NF-κB) on the p65 subunit of the p50/p65 heterodimer inhibits NF-κB DNA binding activity. We have recently shown that p65 is constitutively S-nitrosylated in the lung and that LPS-induced injury elicits a decrease in SNO-p65 levels concomitant with NF-κB activation in the respiratory epithelium and initiation of the inflammatory response. Here, we demonstrate that TNFα-mediated activation of NF-κB in the respiratory epithelium similarly induces p65 denitrosylation. This process is mediated by the denitrosylase thioredoxin (Trx), which becomes activated upon cytokine-induced degradation of thioredoxin-interacting protein (Txnip). Similarly, inhibition of Trx activity in the lung attenuates LPS-induced SNO-p65 denitrosylation, NF-κB activation, and airway inflammation, supporting a pathophysiological role for this mechanism in lung injury. These data thus link stimulus-coupled activation of NF-κB to a specific, protein-targeted denitrosylation mechanism and further highlight the importance of S-nitrosylation in the regulation of the immune response.     

第11届国际生物奥林匹克竞赛(2000)理论试题B(1)

细胞生物学1.删除2 .下列陈述是关于通过细胞膜的转运。在下列空格中从左向右以逐渐增大的顺序 1)～ 7)写出正确陈述的序号。1)大分子被胞吞作用摄入细胞内 ;2 )离子和糖被胞吞作用摄入细胞内 ;3)胶体溶液 (蛋白质、脂类、碳水化合物 )被胞饮作用摄入细胞内 ;4 )脂类可溶性化合物被通道蛋白摄入细胞内 ;5 )细菌被吞噬作用摄入细胞内 ;6)细胞废物被吞噬作用摄入细胞内 ;7)离子通过通道蛋白3.删除4 .在下面 ,你能看到一些蛋白质 ,并列举了一些蛋白质的功能 [(1)～ 8) ]。在蛋白质前方空白处写上适合的功能的序号 (一种蛋白质可能有多于一种的…     

第11届国际生物奥林匹克竞赛(2000)理论试题B(4)

(续 2 0 0 1年第 11期第 4 5页 )5 3.下图是氧气与血红蛋白结合的 5个饱和曲线 ,每 1个曲线从 1个不同的动物获得。根据动物的基础新陈代谢 ,这些曲线的形状各不同。把这些曲线与下面所给动物联系起来 (把曲线的序号填在动物前方 )。象　　　　蛇鸟 (麻雀 )　人鼠5 4 .对在动脉的化学感受器、呼吸速率和肾脏中排出H 的速率和血中 CO2 分压方面的正确的变化作出记号。这些变化发生是为了纠正血中 p H值的下降。动脉的化学感受器呼吸速率兴奋抑制增加减少肾脏中 H 的排泄 血液 CO2 分压增加减少增加减少5 5 .写下与胚外膜相应的数字 :羊…     

Liver Kinase B1 Suppresses Lipopolysaccharide-induced Nuclear Factor κB (NF-κB) Activation in Macrophages

Liver kinase B1 (LKB1), a serine/threonine kinase, is a tumor suppressor and metabolic regulator. Recent data suggest that LKB1 is essential in regulating homeostasis of hematopoietic cells and immune responses. However, its role in macrophages and innate immune system remains unclear. Here we report that macrophage LKB1 inhibits pro-inflammatory signaling in response to LPS. LPS-induced pro-inflammatory cytokines and pro-inflammatory enzymes were monitored in bone marrow-derived macrophages isolated from myeloid cell-specific LKB1 knock out mice and their wild type littermate control mice. LPS induced higher levels of pro-inflammatory cytokines and pro-inflammatory enzymes in bone marrow-derived macrophages from LKB1 KO than those from wild type mice. Consistently, LPS induced higher levels of NF-κB activation in LKB1-deficient macrophages than those in wild type. Further, LPS stimulation significantly increased LKB1 phosphorylation at serine 428, which promoted its binding to IκB kinaseβ (IKKβ), resulting in the inhibition of NF-κB. Finally, LPS injection caused higher levels of cytokine release and more severe tissue injury in the lung tissues of LKB1 KO mice than in those of control mice. We conclude that LKB1 inhibits LPS-induced NF-κB activation in macrophages.     

第11届国际生物奥林匹克竞赛(2000)理论试题B(2)

(续 2 0 0 1年第 10期第 4 2页 )植物解剖和生理学2 4 .下图代表根的水分输导 ,用×标记正确选择 (复数 )A.温度在 1～ 2和 4～ 5状态之间下降B.在 0～ 1和 2～ 4状态之间介质中添加了氰化物C.在 1～ 2和 4～ 5状态之间有足够的氧气D.在 1～ 2和 4～ 5状态之间根不能得到足够的营养2 5 .见下图红或白色闪光 (RF)远红外线闪光 (FRF)上图代表长日照和短日照植物在光照不同变化的情况下的反应。在上述所给的状态之下 ,决定长日照 (短夜 )和短日照 (长夜 )植物是开花 ( )还是不开花 (- )长日照 (短夜 )植物短日照 (长夜 )植物ABCDEF　　…     

Allophycocyanin B (λmax 671, 618 nm)

A hitherto undescribed red fluorescent phycobiliprotein (maximum emission at ∼ 680 nm), characterized by long wavelength absorption maxima in the visible region at 671 nm (ε=172000 M⁻¹·cm⁻¹ per monomer of mol. wt. 30600) and 618 nm, has been purified to homogeneity from a unicellular cyanobacterium, Synechococcus sp., and from a filamentous cyanobacterium, Anabaena variabilis. The name allophycocyanin B has been proposed for the new protein. A. variabilis allophycocyanin B is characterized by a native molecular weight of 89000 ± 5000 (in 0.05 M phosphate at pH 7.2), an isoelectric point of 5.09, and a subunit molecular weight, based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, of 15300. The protein contains one phycocyanobilin chromophore per subunit. In common with allophycocyanin from the same organism, allophycocyanin B does not contain either histidine or tryptophan. In other respects, the amino acid compositions of the two proteins are significantly different. Synechococcus sp. (Anacystis nidulans) allophycocyanin B gives two components of 16000 and 17000 mol. wt., of equal staining intensity, on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Allophycocyanins B from both organisms cross-react with rabbit antisera directed against either Synechococcus sp. or Anabaena sp. allophycocyanin, but not with antisera against the phycocyanins of the same organisms. It is suggested that allophycocyanin B occupies a position between allophycocyanin and chlorophyll a in the energy transfer path from the accessory pigments to species of chlorophyll a with absorption maxima at λ>670 nm.     

B链C端去七肽(B24～B30)胰岛素的分子置换法

一个几近失活的胰岛素类似物———B链C端去七肽 (B2 4～B30 )胰岛素(DHPI)已被结晶 .该晶体属于空间群P2 ₁2 ₁2 ₁,晶胞的 1个独立区内包含有 2个DHPI分子 .应用分子置换法确定了DHPI分子在晶胞中的取向和位置 ,并在 0 .3nm分辨率水平上构建了结构模型 .研究结果表明 ,一个独立区内的 2个DHPI单体分子由一个非晶体学 2次轴联系着 ,该局部 2次轴近似平行于晶体学c轴 .这一特性直接影响了自身旋转函数对该局部对称轴取向的确定     

产生霍乱毒素B亚单位(CT—B)工程菌的发酵条件

高效表达霍乱毒索B亚单位的工程菌MM2菌株．在玉米浆培养基中能高效合成B亚单位,观察了吸光度(OD)、pH及B亚单位产生的动态变化。玉米浆培养基不仅成本低、制备工艺简易,而且B亚单位产量高,在50L发酵罐中培养,B亚单位产量可达40μg／mL。     

B链N端去二肽(B1～2)C端去五肽(B26～30)胰岛素晶体结构的分子置换法研究

以B链羧端去五肽胰岛素(DPI)结构为模型,应用分子置换法对B链N端去二肽(B1～2)C端去五肽(B26～30)胰岛素(DesB1～2DPI)晶体结构进行了研究.DesB1～2DPI晶体单位晶胞中每个结晶学不对称单位包含1个DesB1～2DPI分子.交叉旋转函数和平移函数搜索均找到了明显突出的峰,确定了DesB1～2DPI分子在晶胞中的取向和位置.进一步的三维模型重建和结构精化结果巩固了DesB1～2DPI的分子置换法研究的正确性.