Distal recognition site for classical pathway convertase located in the C345C/netrin module of complement component C5

Previous studies focused on indels in the complement C345 protein family identified a number of potential protein-protein interaction sites in components C3 and C5. Here, one of these sites in C5, near the alpha-chain C terminus, was examined by alanine-scanning mutagenesis at 16 of the 18 non-alanine residues in the sequence KEALQIKYNFSF RYIYPLD. Alanine substitutions affected activities in the highly variable manner characteristic of binding sites. Substitutions at the lysine or either phenylalanine residue in the central KYNFSF sequence had the greatest effects, yielding mutants with <20% of the normal activity. These three mutants were also resistant to the classical pathway (CP) C5 convertase, with sensitivities roughly proportional to their hemolytic activities, but had normal susceptibilities to the cobra venom factor (CVF)-dependent convertase. Synthetic peptide MGKEALQIKYNFS-NH2 was found similarly to inhibit CP but not CVF convertase activation, and the effects of alanine substitutions in this peptide largely reflected those of the equivalent mutations in C5. These results indicate that residues KYNFSF form a novel, distal binding site for the CP, but not CVF convertase. This site lies approximately 880 residues downstream of the convertase cleavage site within a module that has been independently named C345C and NTR; this module is found in diverse proteins including netrins and tissue inhibitors of metalloproteinases.     

小麦不同品种上麦蚜及其天敌的数量变动

试验结果表明小麦品种 (系 )的抗性对麦蚜种群数量影响很大 ,百株蚜量随着小麦品种抗性增强而下降。而同一小麦品种对不同种蚜虫的抗性存在质的差异 ,铭贤 1 69品种 ,蚜高峰期百株蚜量麦长管蚜 63 0头 ,禾谷缢管蚜只有 1 1 5头 ,两者相差 5 5倍。另一方面 ,小麦品种抗性对麦田天敌的种群数量影响不大 ,而对天敌的发生期有些影响。因此 ,小麦品种抗性、天敌对麦蚜的自然控制能力 ,可把小麦中后期的蚜虫虫口密度控制在经济损失允许水平之下。     

应用性外激素监测马尾松毛虫发生数量的初步研究

本研究采用持效期达 3 0天以上的复合橡胶载体的新型诱芯诱捕器对马尾松毛虫进行林间监测 ,发现诱蛾数量与田间调查的幼虫数量有很大的关联性 ,各乡镇每诱捕点平均诱蛾数与 1代、2代幼虫虫株率、平均虫口的变化趋势基本相同     

Signaling Molecule Methylglyoxal Remits the Toxicity of Plumbum by Modifying Antioxidant Enzyme and Osmoregulation Systems in Wheat (Triticum aestivum L.) Seedlings

Russian Journal of Plant Physiology - Methylglyoxal (MG) has traditionally been known as a toxic byproduct of cellular metabolism in plants, which now has been found to function as a novel...     

t-PA昆虫细胞表达及特性分析

应用RT-PCR技术,从人黑色素瘤Bowes细胞株中扩增出人组织型纤溶酶原激活剂(tissue-typeplasminogenactivator,t-PA)cDNA。序列分析证实,与国外的报道完全一致。将含完整阅读框架的人t-PAcDNA克隆至昆虫细胞表达转移载体pBacPAK8中,获得重组质粒pBac-tPA。应用脂质体共转染法,将pBactPA和线性化杆状病毒BacPAK6DNA共转染Tn-5B-1昆虫细胞。经空斑筛选获得11株重组病毒。经PCR鉴定与生物活性测定,获得一株高效表达t-PA的重组病毒BactPA3。在含胎牛血清的培养基中,t-PA表达活性在感染(MOI≈10)后72h左右达到最高,为3.04×103IU／ml,即相当于1.8×104IU／106细胞;在无血清培养基中,t-PA最高表达水平相差不大,但时间为感染后132h左右。经SDS-PAGE纤维蛋白自显影分析,分子量为68kda左右。与从人黑色素瘤细胞培养液中提纯的天然t-PA相比,其受纤维蛋白原激活的特性、和纤维蛋白的亲和力及在血浆中的失活速率基本相同。表达的t-PA在血液循环中的半衰期为7min。     

休眠期间低温累积对杏枝芽生理生化的影响

实验以３个不同低温需求量的杏品种为材料,在休眠时期进行１１种生理生化指标的测定,结果表明,随着低温累积量的增加,枝条与花芽总含水量、自由水含量,呼吸强度逐渐下降,萌芽前回升,束缚水、束／自比值、可溶性糖、可溶性蛋白质含量逐渐增加,到萌芽前减少,游离氨基酸与脯氨酸含量以及ＳＯＤ活性在完成低温需求量时最高,然后逐渐下降,游离氨基酸、脯氨酸含量与低温需求量存在着相关关系,相关系数为ｒ低需,游离＝０．９８     

成骨细胞的培养及阿伦磷酸钠对其的影响

碱性磷酸酶(ALP)活性、骨钙素、Ⅰ型胶原等通常作为骨分化的特异性指标。骨形成蛋白、转化生长因子-β、地塞米松等是促进骨髓基质细胞分裂增殖并定向分化为成骨细胞的特异性因素。矿化液诱导骨髓基质细胞转化为成骨细胞是相关领域学者普遍采用的方法。阿伦磷酸钠在一定浓度下不影响成骨细胞的增殖,甚至可能促进成骨细胞增殖或成熟分化。本文综述了该领域的最新研究进展。     

口服草原兔尾鼠卵透明带3纳米乳剂DNA疫苗免疫效果研究

用免疫不育疫苗控制有害动物的数量成为动物种群数量控制的一个有效措施,对于大多数动物来说．口服饵料发送系统是最好的选择。但是口服疫苗容易产生耐受,且生物利用度低,利用多聚物包裹口服疫苗是一种打破口服耐受．提高其生物利用度的新途径。本文以纳米乳剂作为草原兔尾鼠卵透明带3（Lugurus zone pellucida 3,LZP3）DNA疫苗的发送载体,探讨通过口服途径增强小鼠的免疫效果和抗生育率。用纳米乳剂包裹lzp3 DNA疫苗后,采用强阴离子交换色谱法测定纳米乳剂的包封率．将制备好的质粒纳米乳剂lzp3 DNA疫苗通过口服饵料免疫小鼠,检测到免疫后小鼠的体内产生了特异性的抗LZP3的IgG和IgA。对免疫后小鼠进行抗生育实验,分析生育后免疫小鼠的卵巢病理切片。研究结果表明,用质粒纳米乳剂如p3DNA疫苗通过口服途径免疫．在小鼠的血清和粘液中检测到了特异性的抗LZP3的IgG和IgA,同时也产生了相应的抗生育作用．表明纳米乳剂作为口服不育疫苗的发送载体是可行的,为草原兔尾鼠鼠害的防治提供了理论基础．     

大肠杆菌突变株高密度生长的多因素分析

[背景]pBHR68是表达聚-3-羟基丁酸酯(Poly-3-Hydroxybutyrate,PHB)合成基因簇的高拷贝质粒,大肠杆菌K-12突变菌株S17-3在携带该质粒时生长密度高,耐低pH且在低pH条件下生长时高产可拉酸(Colanic Acid,CA).[目的]系统探究与菌种(大肠杆菌S17-3)及质粒(pBHR...