蜘蛛丝蛋白的结构及其应用

蜘蛛的拖丝是一种既具有抗张强度又具有高度弹性的奇特蛋白质纤维。近看来,生物学者用现代生物工程技术和其它技术对蛛丝蛋白分子的结构和物理特性,主要是机械特性,进行了广泛深入的研究,取得了很大进展,指出了蛛丝蛋白的工业应用价值。1蛛丝蛋白结构研究进展概述编码一种拖丝蛋白（Spidroiril）的部分cDNA克隆以前已获分离产物,但是所预期的氨基酸顺序并不能解释拖丝蛋白的氨基酸组成。此后又分离出一种编码另一拖丝蛋白（SPidloin2）的部分dD：NA克隆,说明蜘蛛的拖丝是由复合蛋白组成的。Spidroin2的氨基酸顺序是一种与Spidro…     

Syk protein tyrosine kinase involves PECAM-1 signaling through tandem immunotyrosine inhibitory motifs in human THP-1 macrophages

Although recent evidence supports a functional relationship between platelet endothelial cell adhesion molecule (PECAM-1) and Syk tyrosine kinase, little is known about the interaction of Syk with PECAM-1. We report that down-regulation of Syk inhibits the spreading of human THP-1 macrophage cells. Moreover, our data indicate that Syk binds PECAM-1 through its immune tyrosine-based inhibitory motif (ITIM), and dual phosphorylation of the ITIM domain of PECAM-1 leads to activation of Syk. Our results indicate that the distance between the phosphotyrosines could be up to 22 amino acids in length, depending on the conformational flexibility, and that the dual ITIM tyrosine motifs of PECAM-1 facilitate immunoreceptor tyrosine-based activation motif-like signaling. The preferential binding of PECAM-1 to Src homology region 2 domain-containing phosphatase-2 or Syk may depend on their relative affinities, and could provide a mechanism by which signal transduction from PECAM-1 is internally regulated by both positive and negative signaling enzymes.     

大连渤海老虎滩海域沉积物可培养放线菌的多样性

【目的】研究大连渤海老虎滩海域可培养放线菌的多样性。【方法】利用5种不同的培养基分离、培养海洋沉积物中的放线菌,并用16S rRNA基因序列对部分放线菌株进行系统发育分析。【结果】根据菌落表型共分离到1215株放线菌。选择271株具有代表性的菌株进行16S rRNA分析,结果表明,251株(92.26%)属于放线菌门,覆盖11个科,15个属;其余20株属于厚壁门和变形菌门;有7株为潜在的新种。【结论】大连渤海老虎滩海域的沉积物中存在较为丰富的放线菌和新种资源,这些菌株为将来开发新的微生物代谢产物奠定了基础。     

Heme Oxygenase-2 Suppress TNF-α and IL6 Expression via TLR4/MyD88-Dependent Signaling Pathway in Mouse Cerebral Vascular Endothelial Cells

Heme oxygenase (HO) represents an intrinsic antiinflammatory system based on its ability to inhibit expression of proinflammatory cytokines. The constitutive isoform heme oxygenase-2 (HO-2) has high expression and activity in cerebral microvascular endothelial cells (CMVEC). This study was undertaken to evaluate the role of HO-2 in regulation of TLR4/MyD88-dependent signaling and to study the effect of HO-2 on the expression and secretion of the proinflammatory cytokines tumor necrosis factor α (TNF-α) and Interleukin-6 (IL6) in CMVEC. HO-2 short hairpin RNA (shRNA) and HO-2 overexpression plasmids were used to observe the effect of HO-2 on proinflammatory cytokines in CMVEC in vitro, and the results showed that the messenger RNA (mRNA) and protein levels of TNF-α and IL6 were increased and decreased, respectively, compared with control groups. LPS-stimulated TNF-α and IL6 mRNA and protein were also reduced in CMVEC treated with an inhibitor of TLR4 signaling, CLI-095, or HO-2 overexpression. CLI-095 and HO-2 overexpression both reduced TLR4 expression in CMVEC, and HO-2 shRNA blocked these effects of CLI-095. CLI-095 and HO-2 overexpression potently suppressed TLR4/MyD88-dependent proinflammatory cytokine expression in CMVEC. These results suggest that HO-2 plays an important role in protecting CMVEC against cytokine-mediated inflammation.     

Characterization of a fungal strain capable of degrading chlorpyrifos and its use in detoxification of the insecticide on vegetables

A fungal strain capable of utilizing chlorpyrifos as sole carbon and energy sources was isolated from soil by enrichment cultivation approach. The half-lives of degradation (DT₅₀) for chlorpyrifos at concentrations of 1, 10, and 100 mg l⁻¹ by the fungal strain DSP in mineral salt medium were measured to be 2.03, 2.93, and 3.49 days, respectively. Two cell-free extracts [E (1:10) and E (1:20)] from the fungal strain DSP in bran–glucose medium were prepared and used to enhance chlorpyrifos degradation on vegetables. Compared with the controls, the DT₅₀ of chlorpyrifos were reduced by 70.3%, 65.6%, 80.6%, 80.6%, and 86.1%, and by 53.8%, 43.2%, 66.0%, 54.3%, and 67.7% on E (1:20) and E (1:10) treated pakchoi, water spinach, Malabar spinach, haricot beans, and pepper, respectively. The 7-day residual values (R ₇) of chlorpyrifos on E (1:10) treated vegetables were all lower than the corresponding maximum residue levels of European Union (EU MRLs), except that the R ₇ value on haricot beans was slightly higher than the corresponding EU MRLs. The results indicate that cell-free extracts could rapidly degrade chlorpyrifos residues on vegetables.     

能量标签技术及其在红树林生态系统能流研究中的应用

传统上认为红树林输出的有机质产生巨大的能流,支持了巨大的河口和近岸水域生态系统的次级生产。但能量标签技术的研究结果却显示红树林输出的有机质的作用并没有如此巨大。用红树碎屑难消化特性来解释此现象,此外数学模型模拟分析发现潮汐的稀释作用也可以解释这种现象。但这两者都不能解释,在其他初级生产者稀少时,红树材输出的有机质可以被大量利用的现象。在有红树林的河口和近海岸水域生态系统中,藻类等非红树初级生产者具有比红树植物更高的初级生产力,而且更容易被动物获得和消化。可以认为是藻类等巨大初级生产力的竞争作用导致红树初级生产在消费者组织中很难被发现,如此上面提到的难题就能得到很好的解决。此外能量标签技术检测出的是红树的初级生产在消费者组织中的相对比率,不是绝对数量值,从此角度看,能量标签技术的结果与传统观点不是矛盾而是互相补充的关系。由此推测红树的初级生产应该还是被消费者所利用,只是它们在消费者初级营养来源组成中占的比例并不大,但其绝对数量并不少。这与传统观点认为的红树的初级生产被大量利用,支撑了具有巨大的次级生产稍有不同。此外,能量标签技术在红树林生态系统中的适用性尚未检验;计算食物组成的数学工具不是很完善;实验设计上考虑的不够全面;对定量研究有一定的影响。