SC-CO2和乙酸乙酯萃取芸香中活性成分的比较分析

为了探讨超临界二氧化碳(supercritical carbon dioxide, SC-CO2)技术与提取物的分级分离在萃取芸香活性成分的应用价值,本研究采用SC-CO2和乙酸乙酯萃取芸香中植物蜡和活性成分,并调查粒径和CO2流量对提取产量的影响。在250 bar、40℃条件下提取,并使第一个分离器冷却到-10℃,可获得较好的提取效率。当粒径较小时,提取过程更快,即内部传质控制该过程。分级分离可选择性去除表皮植物蜡,约占由SC-CO2处理产生的总提取物的77.5%W/W。第二分离器中的获得的提取物中活性化合物可达86.3%W/W。随后采用气相色谱-质谱联用仪(gas chromatography-mass spectrometry, GC-MS)分析表明,乙酸乙酯提取物低于SC-CO2提取物的萃取效率,主要是由于提取物中含有大量的植物蜡。本研究为超临界二氧化碳技术在萃取芸香活性成分方面的提供技术参考。     

长足大竹象消化道不同分段菌群异质性及竹木质纤维素降解能力

[目的]长足大竹象Cyrtotrachelus buqueti消化道共生菌群参与了竹纤维素的降解.本研究旨在揭示长足大竹象幼虫消化道不同分段共生菌群异质性及木质纤维素的降解能力.[方法]通过对16S rRNA测序对长足大竹象幼虫消化道分段口器(YB)、前肠(YFG)、中肠(YMG)和后肠(YHG)进行菌群组成分析及功能...     

适于癌基因表达数据集的新特征提取标准NFEC及其分类新算法研究

癌基因表达数据集具有小样本、高维数之特点,一般的机器学习机难以对其有效分类。因此,通常需要采用某些特征提取度量标准来进行降维处理。可是常用的一些特征提取度量标准亦会导致分类效果欠佳之问题。依据微分容量控制学习机DCCM,提出了一个新的特征提取度量标准NFEC,然后依据NFEC和DCCM,提出了适于癌基因表达数据集的特征提取算法DCCFE。实验表明,新的度量NFEC和新的特征提取算法DCCFE较之现有方法对癌基因表达数据集分类时更为有效。本文的工作意义在于:(1)提出了一个新的更有意义的特征提取度量标准;(2)DCCM可以采用比核函数更为一般的一阶可微函数,因而提出的新的特征提取算法更具普遍应用意义。     

G145R rHBsAg抗原衰减对抗体亲和层析的影响

目的：探讨G145R rHBsAg抗原衰减对抗体亲和纯化的影响与意义。方法：采用抗野生重组HBs G6-McAb制备层析载体,对含rG145R HBsAg的2A8细胞上清做亲和层析。以SDS-PAGE、Western Blot及ELISA等对产物纯度、含量及回收率进行评价,并与同法纯化之野生HBsAg进行比较。结果：梯度洗脱层析显示G145R rHBsAg、自然表达野生HBsAg及其r-wHBsAg三者纯化产物的纯度分别为90.3%、95.2%及93.1%;回收率为43.3%、72.0%及66.4%,其亲和洗脱峰型前者较后两者略宽,主峰前部出现明显顿挫;pH线性梯度洗脱显示,G145R rHBsAg洗脱曲线主峰较前梯度洗脱进一步增宽,顿挫更为明显,并在主峰前出现一低平的蛋白峰。ELISA检测显示HBsAg活性贯穿主峰始终,SDS-PAGE与Weistern blot显示两法洗脱产物纯度（92.5%与89.3%）大致相似,分子大小与野生HBsAg相同。结论：洗脱峰加宽与顿挫作为G145RrHBsAg抗原性渐进性衰减的特征性表现,在同类生物材料实验性制备与产品考评中有一定参考价值。     

萝藦科马利筋族植物化学成分研究进展(Ⅱ)

综述了到目前为止,从马利筋族植物中发现的黄酮、强心甙、生物碱、萜类、苯衍生物类等成分的种类及其分布,并介绍了一些化合物的药理作用以及黄酮类和C21甾体化合物在鹅绒藤属化学分类中的作用.     

重组蛋白质纯化中切割蛋白酶的选择与应用进展

现代生物医药的发展越来越依赖大分子药物的开发与应用,其中蛋白质药物所占的比重越来越高,生产需求进一步加大.重组蛋白质技术作为一种方便的蛋白质生产来源,日益得到广泛运用.重组蛋白质纯化过程中往往使用到融合亲和纯化标签,然而这些冗余的标签在蛋白质精细化生产中,尤其是作为蛋白质医药存在时,是必须被予以去除的.切割蛋白酶发挥着不可替代的作用.本文就现有的各种常用切割蛋白酶进行比较和总结,为重组蛋白质生产与科研者提供参考.     

Functional Genomics Approach to Identifying Genes Required for Biofilm Development by Streptococcus mutans

Streptococcus mutans, the primary etiological agent of human dental caries, is an obligate biofilm-forming bacterium. The goals of this study were to identify the gene(s) required for biofilm formation by this organism and to elucidate the role(s) that some of the known global regulators of gene expression play in controlling biofilm formation. In S. mutans UA159, the brpA gene (for biofilm regulatory protein) was found to encode a novel protein of 406 amino acid residues. A strain carrying an insertionally inactivated copy of brpA formed longer chains than did the parental strain, aggregated in liquid culture, and was unable to form biofilms as shown by an in vitro biofilm assay. A putative homologue of the enzyme responsible for synthesis of autoinducer II (AI-2) of the bacterial quorum-sensing system was also identified in S. mutans UA159, but insertional inactivation of the gene (luxS_Sm) did not alter colony or cell morphology or diminish the capacity of S. mutans to form biofilms. We also examined the role of the homologue of the Bacillus subtilis catabolite control protein CcpA in S. mutans in biofilm formation, and the results showed that loss of CcpA resulted in about a 60% decrease in the ability to form biofilms on an abiotic surface. From these data, we conclude that CcpA and BrpA may regulate genes that are required for stable biofilm formation by S. mutans.     

Synchronous Elicitation of Development in Root Caps Induces Transient Gene Expression Changes Common to Legume and Gymnosperm Species

Root cap development in cereals and legumes is self-regulated by a repressor that accumulates in the extracellular environment, and immersing the root tip into water results in renewed cap development. By exploiting this phenomenon, root cap mitosis and differentiation can be synchronously induced among populations. In Pisum sativum L., messenger RNA (mRNA) differential display revealed changes in expression of approximately 1% of the sample mRNA population within minutes of induced cap turnover. This profile changes sequentially over a period of 30 min, then stabilizes. Microarray analysis of Medicago truncatula root caps confirmed changes in expression of approximately 1% of the target population, within minutes. A cell specific marker for cap turnover exhibited the same temporal and spatial expression profile in the gymnosperm species Norway spruce (Picea abies) as in pea. Induced cap development provides a means to profile cell-specific gene expression among phylogenetically diverse species from the early moments of mitosis and cellular differentiation.     

贮藏条件对河西走廊四种旱生灌木种子萌发的影响

不同贮藏条件下,探讨了河西走廊枸杞(Lycium barbarum)、黑果枸杞(L.rutheni-cum)、花棒(Hedysarum scorpaium)和泡果白刺(Nitraria sphaerocarpa)4种旱生灌木种子萌发情况。结果表明:枸杞、黑果枸杞和花棒种子萌发对贮藏条件有一致性的响应,即经过低温湿润(-5℃和4℃)贮藏后有较高的萌发率、较快的萌发速度和较早的萌发开始时间,贮藏条件对泡果白刺的种子萌发(<30%)的影响较小;冬季冷屋贮藏后(-5℃,湿润)的枸杞种子萌发率(68%)显著大于冰箱贮藏(4℃,湿润)和室温干燥贮藏(<20%);冰箱和冬季冷屋贮藏后黑果枸杞种子萌发率约80%,室温干燥贮藏后萌发率仅为5%;冰箱和冬季冷屋贮藏后的花棒种子萌发率达到88%和65%,干燥贮藏后为40%。低温层积(-5℃和4℃)是打破枸杞、花棒和黑果枸杞种子休眠的有效方法之一。