Bacillus subtilis Z-3菌株纤溶酶的分离纯化研究

为获取微生物源溶栓药物,从土壤中获得产纤溶酶活性较高的1株枯草芽孢杆菌(Bacillus subtilis)Z-3。从Z-3菌株的发酵液中提取纤溶酶,利用DEAE-Sepharose Fast Flow阴离子交换层析和聚丙烯酰凝胶电泳等方法,对纤溶酶进行分离纯化。分离纯化得到1个单一组分(BSFE-1),SDS-PAGE电泳检测为单一条带,BSFE-1表观分子量为48 kDa,等电点为10.5,属丝氨酸蛋白酶类,纤维蛋白平板法检测纤溶酶活性BSFE-1的比活力为4 494.099 U/mg,BSFE-1在4~50℃和pH 4~11之间活性较稳定。     

BICHARACTERISTICAL THEORY AND ITS APPLICATION FOR UNSTEADY COMPRESSIBLE AND INVISCID FLOW WITH SYMMETRIC AXIS

The Bicharacteristics-Method for unsteady, compressible and inviscid flow has been developed in four . dimensional time-space. A new shock-tracing has been presented. A successful numerical solution for reflexion and focusing of a shock has been made.     

基于改进广义回归神经网络和主成分分析的宽带DOA估计

为了获取较高的宽带信号的DOA(direction-of-arrival)估计精度,提出了基于改进的广义回归神经网络(IGRNN,improved generalized regression neural network)和主成分分析(PCA,principalcomponent analysis)的宽带DOA估计算法。选用PCA方法对训练样本进行降维,以降低神经网络的复杂度;利用粒子群算法优化GRNN的参数;根据选取不同的聚焦角度确定粗估计、精估计的训练模型,通过粗估计得出目标的大致方位后,利用精估计模型得出最终的估计结果,避免了聚焦角度对估计精度的影响。仿真结果表明,本文提出的算法具有较好的估计精度和较高的工作效率。     

Isolation by isoelectric focusing of humic-urease complexes from earthworm (Eisenia fetida)-processed sewage sludges

 Vermicomposting is an eco-biotechnological process that transforms energy-rich and complex organic substances into a stabilized humus-like product. In a laboratory experiment, Eisenia fetida (Sav.) earthworms were employed to process putrescible sewage sludges into a high-value biofertilizer, very rich in urease activity and humic-urease complexes (stabilized extracellular enzymes). Extracellular humic-urease complexes were extracted by a single 24-h extraction at 37  °C using neutral pyrophosphate (0.1 M); then, the extracts were dialysed and characterized by means of an analytical isoelectric focusing technique. This technique gave a multiplicity of humic bands enzymatically active, with isoelectric points ranging from 4.8 to 5.6. The results demonstrated that, after an 18-week incubation period, sewage sludge had undergone a biochemical evolution, which caused a doubling of absolute urease activity and a six-fold increase in specific activity (activity with reference to the humic C fraction). The biochemical evolution of the vermicompost was evaluated also from the sharp decrease in pyrophosphate-extractable C and water-soluble C. Stabilization of organic C during vermicomposting and the activity of humic-urease complexes expressed at low pH values are of extreme importance when organic wastes are used in acid soils for biochemical restoration purposes. Received: 10 June 1999     

一种新型血栓溶酶的分离提纯及等电点测定

中国根霉12（Rizopus chinesis 12）菌株产生的血栓溶酶存在于发酵液中,首先经过饱和度为60%的硫酸铵盐析处理,再经半透膜透析去离子浓缩后,通过CM-C和Sephadex-G100凝胶层析,浓缩含有活性组分的层析洗脱兴,得到血栓溶酶组制品。经等电聚焦法证明为一纯组分,而且得到它的等电点为8.2。     

等电聚焦电泳法测定羽衣甘蓝自交不亲和性的研究

利用聚丙烯酰胺凝胶等电聚焦电泳法,研究了羽衣甘蓝强自交不亲和系、弱自交不亲和系与自交亲和系的柱头和花粉蛋白质谱带,并进行自交,以考察亲和指数。结果表明:强自交不亲和系的成熟柱头(S)和弱自交不亲和系的成熟柱头的蛋白谱带有明显差异;强自交不亲和系有特异谱带的出现,而弱自交不亲和系和自交亲和系柱头上没有特异谱带。对比自交不亲和系开花前2~3 d的柱头(S′)与成熟柱头(S)的蛋白质谱带发现了S特异蛋白质的准确位置,其等电点为8.5~9.1。此法可用于鉴定羽衣甘蓝的自交不亲和性。用同种方法处理花粉,没有发现自交不亲和系的特征谱带。     

壳聚糖絮凝回收分级等电沉淀后鱼糜漂洗水中蛋白质

为实现鱼糜漂洗水中蛋白质的洁净回收,同时达到净化鱼糜漂洗水及提高资源利用率的目的,该文针对分级等电沉淀回收蛋白质之后的低蛋白浓度废水,研究了蛋白-壳聚糖絮凝过程,探索了主要动力学和热力学因素对絮凝过程的影响;并根据Box-Benhnken设计进行了优化试验。结果表明,狭鳕鱼鱼糜漂洗水中蛋白质等电点主要集中在4.30和5.50,分级回收后蛋白质的回收率达到77.7%。其中絮凝时间、壳聚糖用量和脱乙酰度、絮凝温度和p H值对壳聚糖絮凝蛋白质均有影响,而絮凝温度的影响更多体现在50℃以上的较高温度区域。根据响应面分析结果,在脱乙酰度95%,反应时间90 min,p H值8.04,壳聚糖用量369 mg/L,温度19.6℃的条件下,可获得94.75%的蛋白总回收率,废水中蛋白质量浓度降至0.37 mg/m L以下。研究结果为富蛋白生产废水处理提供了技术参考。     

Peroxidase isozyme differences in tall fescue cultivars and allopolyploid accessions

Summary The use of isoelectric focusing for the isozymic identification of cultivars and wild forms in tall fescue (Festuca arundinacea Schreb.) and determination of ploidy effects was investigated. Peroxidase zymograms from allopolyploid accessions (4x, 6x, 8x, and 10x, x=7) and randomly sampled plants of the cultivars Kenhy, Kentucky 31, and Missouri 96, were compared for band number, position, and staining intensity. There was little isozymic variation among plants in the tetraploid and hexaploid, but considerably more in the octoploid and decaploid members of the series. Yet no significant effects of ploidy on isozyme complexity or band number were observed. There were no consistent differences in band number, position, or frequencies among the three cultivars in spite of their diverse parentage. Isoclectric focusing can be used successfully in tall fescue, but the limited variability of the peroxidases encourages investigation of other isozyme systems in the future.Contribution from the Missouri Agricultural Experiment Station. Journal Series No. 8627. Research supported by USDA-SEA Competitive Research Grant 5901-0410-9-0366-0.     

野生稻酯酶等电聚焦电泳分析

 对16个野生稻种(基因组分别为AA、BB、CC、CCDD、BBCC、EE和FF)的酯酶等电聚焦电泳分析表明:普通野生稻组的普通野生稻系和宽叶野生稻系、狭叶野生稻组的酯酶酶谱各有其特定模式,这和传统的稻属分类结果相一致。同种野生稻不同地理分布地收集的样品酯酶酶谱模式基本相同,但有些物种有差异。酯酶酶谱可以作为野生稻分类的依据之一,又能揭示同一野生稻种内细微遗传差异。     

Extreme air pollution as a focusing event: A case study of the ‘Airpocalypse’ in Beijing,January 2013

Sudden events of crisis (‘focusing events’) trigger intense media reporting, which in turn can prompt political decision‐makers to respond with an adjustment of existing policies. As such, focusing events can potentially lead to long‐term policy change on a certain issue. This article explores the sudden and intense period of air pollution in Beijing in January 2013 as a focusing event. The episode, which international media referred to as ‘Airpocalypse’, triggered widespread discussion and policy adjustments that can be assumed to have accelerated the control of air pollution in China. The ‘Airpocalypse’ was not the first event of intense air pollution in Beijing, but the only one which seemingly caused lasting sociopolitical changes. The aim of this article is to explore the underlying situational factors that enabled the ‘Airpocalypse’ to be more relevant than other events of severe air pollution. This paper argues that a combination of historically high pollution, improved access to information, increasing government willingness to address the issue, and the ability of media to more openly discuss air pollution created a public pressure situation to which the government was prompted to respond in a stronger way than during previous events of heavy air pollution.