Generation and antitumor effects of an engineered and energized fusion protein VL-LDP-AE composed of single-domain antibody and lidamycin

Type IV collagenase plays a pivotal role in invasion, metastasis and angiogenesis of tumor. Single domain antibodies are attractive as tumor-targeting vehicle because of their much smaller size com-pared with antibody molecules produced by conventional methods. Lidamycin (LDM) is a potent enediyne-containing antitumor antibiotic. In this study an engineered and energized fusion protein VL-LDP-AE composed of lidamycin and VL domain of mAb 3G11 directed against type IV collagenase was prepared using a novel two-step method. First a VL-LDP fusion protein was constructed by DNA recombination. Secondly VL-LDP-AE was obtained by molecular reconstitution. In MTT assay, VL-LDP-AE showed potent cytotoxicity to HT-1080 cells and KB cells with IC50 values of 8.55×10-12 and 1.70×10-11 mol/L, respectively. VL-LDP-AE showed antiangiogenic activity in chick chrorioallantoic membrane (CAM) assay and tube formation assay. In in vivo experiments, VL-LDP-AE was proved to be more effective than free LDM against the growth of subcutaneously transplanted hepatoma 22 in mice. Drugs were given intravenously on day 3 and 10 after tumor transplantation. Compared in terms of maximal tolerated doses, VL-LDP-AE at 0.25 mg/kg suppressed the tumor growth by 89.5%, LDM at 0.05 mg/kg by 69.9%, and mitomycin at 1 mg/kg by 35%. Having a molecular weight of 25.2 kDa, VL-LDP-AE was much smaller than other reported antibody-based drugs. The results suggested that VL-LDP-AE would be a promising candidate for tumor targeting therapy. And the 2-step approach could serve as a new technology platform for making a series of highly potent engineered antibody-based drugs for a variety of cancers.     

猪生长激素基因在杆状病毒载体系统中的表达

通过对猪生长激素(pGH)基因的cDNA进行测序,得到pGH cDNA的全序列,并与Seeburg等报道的序列进行了比较和讨论.然后利用具人工合成启动子和多角体蛋白XIV启动子的转移载体质粒pSXIVVI+X3/4构建出含pGH基因的重组质粒pX3/4-pGH.将pX3/4-pGH与致死缺失型线性化AcMNPV-OCC- DNA共转染Sf9细胞,构建出既能形成多角体又能表达pGH基因的苜蓿丫纹夜蛾核多角体重组病毒AcMNPV-pX3/4-pGH-OCC+.感染重组毒株的Hi 5细胞可溶蛋白及其培养上清的SDS-PAGE和Western blot的分析结果表明,感染细胞的蛋白电泳带的20.7 kDa处有一条猪生长激素特异带,但培养上清中没有.凝胶黑度扫描估测结果显示pGH蛋白占细胞可溶蛋白的4.48%.     

非线性奇摄动多种群生态竞争-捕食系统的渐近解

利用局部坐标系统和边界层函数。讨论了一类多种群生态竞争——捕食非线性奇摄动系统的渐近性,得出了其任意r阶的渐近估计。     

一株非谷氨酸依赖型聚γ-谷氨酸高产菌株的鉴定与诱变育种

从发酵制品中分离到一株不依赖谷氨酸作为发酵底物的高产菌株PGA-N, 通过形态、生理生化试验和遗传学研究, 确定PGA-N为地衣芽胞杆菌(Bacillus licheniformis)。根据该菌株的产生环境, 设计了无L-谷氨酸发酵基础培养基, 并对该培养基进行了碳氮源优化和菌种诱变筛选。PGA-N经过亚硝基胍和紫外线诱变筛选后得一突变株——PGA-N-C10, 其γ-PGA的产量提高到8.82 g/L。实验还考察了搅拌转速与细胞生物量、γ-PGA产量以及γ-PGA分子量之间的关系, 在搅拌速度为400 r/min时, γ-PGA产率可高达11.00 g/L。     

湖南地区1013例亲子鉴定中的STR突变位点研究

对亲子鉴定常用的ABI公司Indentifiler荧光标记复合扩增试剂盒中的15个短串联重复序列及D14S306、D16S3391、D5S2500、D12S391、D13S796、D1S518位点的突变现象进行研究.在1013例认定亲子关系案例中,对发现有一个基因位点发生突变的案例增加8个常染色体STR（short tandem repeat）基因座检测,使其父权相对机会（RCP）大于99.999%以上,并对突变位点进行测序.在1013例认定亲子关系案例中,发现11例有一个基因位点发生突变,8次突变事件为父源性突变,突变位点包括vWA、FGA、D14S306、D13S317、D21S11、CSFIPO、D16S3391;其余3例突变来源不明,包括FGA、D13S796、D3S1358.以vWA和FGA的突变率最高,为0.15%,平均突变率为（0.09±0.370×10^-3）%.本鉴定所常用的21个基因座,突变率低,具有较高的推广价值.     

米根霉利用纯糖和不同预处理玉米秸秆酶解糖生产L-乳酸

通过单因素实验设计,优化米根霉摇瓶发酵产L-乳酸。在此基础上,以蒸气爆破和碱处理玉米秸秆酶解液为混合C源,与纯糖对比,研究不同预处理玉米秸秆混合C源对米根霉发酵产L-乳酸的影响。结果显示:在初始葡萄糖质量浓度100g/L、(NH4)2SO4质量浓度2g/L、接种量6%(体积分数)、转速170r/min、发酵12h后添加30g/LCaCO3的条件下,米根霉发酵产L-乳酸质量浓度为69.15g/L。米根霉发酵不同预处理玉米秸秆酶解混合C源,木糖的存在影响了米根霉的C代谢网络,降低L乳酸的产量。     

微生物对工业杀菌剂的抗药性研究进展

就微生物对工业杀菌剂的抗药性概念、研究概况及抗药性的产生机理进行了介绍,为科学合理使用和开发新型工业杀菌剂提供科学依据。     

海河流域农田生态系统环境损益分析

根据生态系统服务的内涵,建立了海河流域农田生态系统服务功能评价指标体系,并利用市场价值法、影子工程法和机会成本法等,定量评价了海河流域农田生态系统服务的经济价值和农田环境成本.结果表明：2005年,海河流域农田生态系统环境效益总价值为1802.64亿元;其中,调节功能的价值（794.16亿元）占44.06%,支持功能的价值（1008.48亿元）占55.94%,提供产品和文化功能未进行核算.从不同的功能类型来看,其价值量大小依次为释氧>涵养水源>营养元素循环>土壤保持>废弃物净化>环境净化>固碳>秸秆还田.2005年,海河流域化肥流失和温室气体排放的环境成本较大,为422.93亿元.其中,化肥流失量为427.42×10⁴ t,成本为151.91亿元;产生的温室气体折算为CO₂的量为3599.65×10⁴ t,成本为271.02亿元.     

Soil carbon sequestrations by nitrogen fertilizer application, straw return and no-tillage in China's cropland

Soil as the largest global carbon pool has played a great role in sequestering the atmospheric carbon dioxide (CO₂). Although global carbon sequestration potentials have been assessed since the 1980s, few investigations have been made on soil carbon sequestration (SCS) in China's cropland. China is a developing country and has a long history of agricultural activities. Estimation of SCS potentials in China's cropland is very important for assessing the potential measures to prevent the atmospheric carbon rise and predicting the atmospheric CO₂ concentration in future. After review of the available results of the field experiments in China, relationships between SCS and nitrogen fertilizer application, straw return and no‐tillage (NT) practices were established for each of the four agricultural regions. According to the current agricultural practices and their future development, estimations were made on SCS by nitrogen fertilizer application, straw return and NT in China's cropland. In the current situation, nitrogen fertilizer application, straw return and zero tillage can sequester 5.96, 9.76 and 0.800 Tg C each year. Carbon sequestration potential will increase to 12.1 Tg C yr⁻¹ if nitrogen is fertilized on experts' recommendations. The carbon sequestration potentials of straw return and NT can reach 34.4 and 4.60 Tg C yr⁻¹ when these two techniques are further popularized. In these measures, straw return is the most promising one. Full popularization of straw return can reduce 5.3% of the CO₂ emission from fossil fuel combustion in China in 1990, which meets the global mean CO₂ reduction requested by the Kyoto Protocol (5.2%). In general, if more incentive policies can be elaborated and implemented, the SCS in China's cropland will be increased by about two times. So, popularization of the above‐mentioned agricultural measures for carbon sequestration can be considered as an effective tool to prevent the rapid rise of the atmospheric CO₂ in China.     

山姜素对鱼源耐药性嗜水气单胞菌体外抗菌作用的研究

旨为探究山姜素对耐药性嗜水气单胞菌的体外抑菌效果及其作用机制.通过测定山姜素对嗜水气单胞菌生长、细菌形态、电导率、乳酸脱氢酶(LDH)、蛋白质代谢和DNA的影响,研究山姜素对耐药性嗜水气单胞菌的抑菌机制.山姜素对5株鱼源耐药性嗜水气单胞菌的最小抑菌浓度(MIC)和最小杀菌浓度(MBC)分别为128-256μg/mL和5...