Attachment of marine sponge cells of Hymeniacidon perleve on microcarriers

Toward the development of an in vitro cultivation of marine sponge cells for sustainable production of bioactive metabolites, the attachment characteristics of marine sponge cells of Hymeniacidon perleve on three types of microcarriers, Hillex, Cytodex 3, and glass beads, were studied. Mixed cell population and enriched cell fractions of specific cell types by Ficoll gradient centrifugation (6%/8%/15%/20%) were also assessed. Cell attachment ratio (defined as the ratio of cells attached on microcarrier to the total number of cells in the culture) on glass beads is much higher than that on Cytodex 3 and Hillex for both mixed cell population and cell fraction at Ficoll 15-20% interface. The highest attachment ratio of 41% was obtained for the cell fraction at Ficoll 15-20% interface on glass beads, which was significantly higher than that of a mixed cell population (18%). The attachment kinetics on glass beads indicated that the attachment was completed within 1 h. Cell attachment ratio decreases with increase in cell-to-microcarrier ratio (3-30 cells/bead) and pH (7.6-9.0). The addition of serum and BSA (bovine serum albumin) reduced the cell attachment on glass beads.

地衣芽孢杆菌GXN151的纤维素酶基因cel12A的序列分析及其在大肠杆菌中的表达

地衣芽孢杆菌菌株GXN151的cel12A基因为783bp,可编码含261个氨基酸的羧甲基纤维素酶Cel12A,Cel12A的N末端第1～28氨基酸具典型的信号肽特征、第9～31氨基酸具跨膜功能域特征、第104～261氨基酸形成家族12糖基水解酶(glycosylhydrolase)功能域。将编码其第73～261氨基酸的DNA序列克隆到大肠杆菌表达载体pET30a(+)得表达质粒pGXN12A,用1mmol/LIPTG诱导处理JM109(DE3)/pGXN12A的培养液6hpGXN12A的表达量达到最高,在JM109(DE3)和BL21(DE3)pLysS中该表达蛋白质可分别占菌体胞内总蛋白的54.3%和20.9%。在含羧甲基纤维素的LA平板上JM109(DE3)/pGXN12A和BL21(DE3)pLysS/pGXN12A表现有较弱的羧甲基纤维素酶活性,说明重组的Cel12A的催化功能域具有独立的催化活性。包含体检测表明pGXN12A在JM109(DE3)中的表达产物大部分形成不溶性包含体。

Highly enantioselective resolution of terminal epoxides with cross-linked polymeric salen-Co(III) complexes

Crosslinked polymeric salen-Co(III) complexes derived from a novel dialdehyde and a trialdehyde were synthesized and employed in the hydrolytic kinetic resolution (HKR) of terminal epoxides. Up to 99%, ee were obtained with only 0.16-0.02 mol%,, of catalyst (based on catalytic unit). (C) 2003 Elsevier Ltd. All rights reserved.

丁香幼胚离体培养及组织快繁(英文)

利用正交试验进行了丁香的幼胚离体培养和增殖培养两方面的研究,对基本培养基、糖浓度、谷氨酰胺浓度、BA浓度、NAA浓度都进行了仔细的筛选。结果表明:幼胚培养的最适胚龄为50天;幼胚培养所需要的最适培养基为附加BA(0.1mg稬-1)、NAA(0.001mg稬-1),糖50(g稬-1),Gln(400mg稬-1)的Monnier培养基,幼胚萌发率可达91.7%;Gln的加入对幼胚培养有显著影响。此外,丁香实生苗最适的增值培养基为MS+BA(2mg稬-1)、NAA(0.01mg稬-1)、IBA(0.5mg稬-1)、Gln(100mg稬-1),此时繁殖系数大于3.6,可以满足生产需要。图1表7参8。

Combined single-pass conversion of methane via oxidative coupling and dehydroaromatization

A new reaction mode, i.e., the combined single-pass conversion of methane via oxidative coupling (OCM) over mixed metal oxide (SLC) catalysts and dehydroaromatization (MDA) over Mo/HZSM-5 catalysts, is reported. With the assistance of an OCM reaction over SLC catalysts in the top layer of the reactor, the deactivation resistance of Mo/HZSM-5 catalysts is remarkably enhanced. Under the selected reaction conditions, the CH(4) conversion decreased from similar to18 to similar to1% and the aromatics yield decreased from 12.8 to 0.1%, respectively, after running the reaction for 960 min on both 6Mo/HZSM-5 and SLC-6Mo/HZSM-5 catalyst system without O(2) in the feed. On the other hand, for the SLC-6Mo/HZSM-5 catalyst system with O(2) in the feed, the deactivation was improved greatly, and after 960 min onstream the CH(4) conversion and aromatics yield were still as high as 12.0 and 8.0%, respectively. The promotion effect mainly appears to be associated with in situ formation of CO(2) in the OCM layer, which reacts with coke via the reverse Boudouard reaction.

In situ IR spectroscopic studies on molybdenum nitride catalysts: active sites and surface reactions

Recent IR spectroscopic studies on the surface properties of fresh Mo2N/gamma-Al2O3 catalyst are presented in this paper. The surface sites of fresh Mo2N/gamma-Al2O3, both Modelta+ (0<δ<2) and N sites, are probed by CO adsorption. Two characteristic IR bands were observed at 2045 and 2200 cm(-1), due to linearly adsorbed CO on Mo and N sites, respectively. The surface N sites are highly reactive and can react with adsorbed CO to form NCO species. Unlike adsorbed CO on reduced passivated one, the adsorbed CO on fresh Mo2N/gamma-Al2O3 behaves similarly to that of group VIII metals, suggesting that fresh nitride resembles noble metals. It is found that the surface of Mo nitrides slowly transformed into sulfide under hydrotreating conditions, which could be the main reason for the activity drop of molybdenum nitride catalysts in the presence of sulfur-containing species. Some surface reactions, such as selective hydrogenation of 1,3-butadiene, isomerization of 1-butene, and hydrodesulfurization of thiophene, were studied on both fresh and reduced passivated Mo2N/gammaAl(2)O(3) catalysts using IR spectroscopy. The mechanisms of these reactions are proposed. The adsorption and reaction behaviors of these molecules on fresh molybdenum nitride also resemble those on noble metals, manifesting the unique properties of fresh molybdenum nitride catalysts. Mo and N sites are found to play different roles in the adsorption and catalytic reactions on the fresh Mo2N/gammaAl(2)O(3) catalyst. Generally, Mo sites are the main active sites for the adsorption and reactions of adsorbates; N sites are not directly involved in catalytic reactions but they modify the electronic properties of Mo sites.

The synthesis of nanostructured W2C on ultrahigh surface area carbon materials via carbothermal hydrogen reduction

Nanostructured tungsten carbides were synthesized, for the first time, with a size distribution of 5-12 nm on ultrahigh surface area carbon material, by carbothermal hydrogen reduction (CHR) at 850degreesC and metal Ni promoted CHR at 650 degreesC.

分散型流域农业非点源污染模型研究

本文以探讨农业非点源污染形成的主要机制和预测流域农业非点源污染为目标 ,从研究方法和实践应用两方面进行了深入的研究。以辽西地区典型农业小流域非点源污染形成的特点为基础 ,将机理与建模理论相结合 ,通过建立一个包含流域水文模型、产污模型、汇污模型等子模型的模型系统 ,进行农业非点源污染的预测。建模中针对流域内非点源污染现象的空间差异 ,采用分散参数结构的建模思想 ,运用一种以等级为基础 ,兼顾尺度效应的流域空间单元划分方法 ,同时还探讨了 GIS与模型相结合的途径 ,包括利用 GIS进行空间分析 ,建立和管理模型所需的数据库等。应用结果显示了该模型系统具有良好的适用性和灵活性。

Simultaneous genotyping of multiplex single nucleotide polymorphisms of the K-ras gene with a home-made kit

Accurate and fast genotyping of single nucleotide polymorphisms (SNPs) is important in the human genome project. Here an automated fluorescent method that can rapidly and accurately genotype multiplex known SNPs was developed by using a homemade kit, which has lower cost but higher resolution than commercial kit. With this method, oncogene K-ras was investigated, four known SNPs of K-ras gene exon 1 in 31 coloerctal cancer patients were detected. Results indicate that mutations were present in 8(26%) of 31 patients, and most mutations were localized in codon 12. The presence of these mutations is thought to be a critical step and plays an important role in human colorectal carcinogenesisas. (C) 2003 Elsevier B.V. All rights reserved.

Reversed capillary electrochromatography: Investigation of peak symmetry for eluting curves of solutes

The transport processes of components in capillary electrochromatographic column was investigated based on the basic model of relaxation theory. A principal transport equation of chromatographic relaxation theory was established and mathematical expressions for eluting curves were obtained under the situations of both capillary electrophoresis and chromatography. Characteristics of peak symmetry and its effecting factors are discussed. Tailing peaks, symmetrical peaks and fronting peaks would be observed simultaneously, which was further proved with reversed capillary electrochromatographic experiments.

红皮云杉幼树不同光环境下生理生态特征研究

为了探讨红皮云杉光合特征与树木枝叶分布格局,生物量及其分配的关系,采用人工控制光照环境,在4个光照条件下进行红皮云杉生长试验,结果表明,红皮云杉幼树瞬时最大净光合速率以透光70%处理最大,10%处理最小,对数据进行方差分析,结果差异显著;并且净光合速率最大的处理其暗呼吸速率也最大,光补偿点和光饱和点也随透光率而变化,透光率小(10%)的处理光补偿点也小,说明云杉幼树对庇荫环境的适应;不同光照条件下幼树的形态特征也表现出明显差异,长期生活在相对较暗的光环境中,形成细而高的树干,侧枝数量增加、长度加长,侧枝角度增大;云杉小苗(9年生以前)以相对照度70%处理生物量最大,9年生以后以全光区生物量最大,说明云杉在9年生以前耐庇荫,9年生以后喜光。

环境中基因工程微生物生态学研究

详细阐述了基因工程微生物(GEM)在环境释放中需考虑的主要问题:GEM的构建、基因转移、适合度、扩散、转运和潜在的生态影响等,并针对GEM特定的生态学特征和生态影响,提出了基因工程微生物生态学研究宜采取“具体问题具体分析”的策略,制定相应的研究方案,为安全有效地在非受控条件下应用GEM铺平道路。

交叉接种后固氮放线菌基因稳定性研究

放线菌Frankia与放线菌根植物在根瘤中共生的现象发生在8科24属被子植物上.系统发育分析表明:Frankia可分为4个族,其菌株对寄主植物有明显的偏好性.用大理旱冬瓜根瘤接种昆明和武定旱冬瓜幼苗,收集幼苗上的根瘤,再对幼苗接种数次.用武定旱冬瓜和川滇桤木幼苗做同样实验,最后对Frankia的16SrRNA基因进行ARDRA分析,发现接种幼苗根瘤中Frankia与接种根瘤中Frankia产生相同的16SrRNA基因ARDRA带型.

科尔沁沙地15种禾本科植物种子萌发特性比较

在实验室条件下,观测了科尔沁沙地乌兰敖都地区禾本科植物当年新采种子的萌发特点。15种植物中,披碱草、糙隐子草、冠芒草、大油芒、芦苇、虎尾草、野古草、狼尾草的发芽率超过80％,水稗草、牛鞭草、虱子草、狗尾草的发芽率不足10％。1～3d开始发芽的植物有大油芒、画眉、芦苇、虎尾草、披碱草、冠芒草、毛马唐、糙隐子草、超过10d基本不发芽的植物包括狗尾草、虱子草、牛鞭草.发芽持续期小于10d的植物包括毛马唐、水稗草、芦苇、画眉草、大油芒;发芽持续期21～30d的植物有披碱草、冠芒草。发芽种子超过总发芽种子的50％需要天数为虎尾草2d,芦苇3d,大油芒4d,披碱草5d,糙隐子草5d,野古草7d,冠芒草7d,狼尾草10d。与英国Sheffield地区相比,乌兰敖都地区一年生禾草发芽率低的所占比重更大,发芽更为缓慢;乌兰敖都地区多年生禾草的发芽率差别很小,但发芽更为缓慢。杂草植物萌发的风险分摊能力相对明显,因此抗干扰能力相对较强。