凝胶过滤法纯化裂褶多糖检测方法的改进

凝胶过滤洗脱液中多糖含量一般采用硫酸-苯酚等化学显色法测定,然后根据洗脱曲线得到纯化的组分,但化学方法费时且消耗试剂.本研究采用350 nm非特征性吸收波长对2种不同纯度裂褶多糖样品PSG1和PSG2的洗脱液直接测定吸光度,与硫酸-苯酚法490 nm测定得到的洗脱曲线基本一致,即分别可得到4个和2个组分,同时采用HPLC对分离效果进行了检测.研究表明,采用350 nm波长直接检测可实现不同纯度裂褶多糖的分离.利用本法检测其他多糖的效果有待进一步研究.     

萱草花粉类动力蛋白生物物理学及药理学性质

利用FPLC技术从萱草花粉中鉴定并纯化了动力蛋白,研究了它的酶学性质及部分生物化学性质。结果如下:纯化的类动力蛋白分子量为100kD,等电点pI=6·15和6·80。在280nm波长激发下,最大的荧光发射波长是346nm。荧光光谱分析结合紫外吸收光谱及导数光谱分析推断它含有色氨酸和酪氨酸残基。药理学性质研究表明巯基可能在酶的活性中心起重要作用。     

发酵液中色氨酸含量高通量快速测定

为了高通量筛选色氨酸工程菌,利用色氨酸与MAA在酸性条件下产生荧光物质(激发波长253 nm,发射波长450nm),荧光强度与色氨酸含量在一定范围内成正比的原理,建立了96孔微孔板中高通量测定发酵液色氨酸含量的方法。反应液80℃反应15 min后,测量荧光强度。线性范围为1 mg.L-1~100 mg.L-1,为大规模筛选色氨酸基因工程菌打下了基础。     

UV-B对两种藻光合色素和多糖含量的影响

本文研究了微绿球藻(Nanochloropsis sp.)和海洋原甲藻(Prorocentrum micans)在不同辐射强度的UV-B照射下的光合色素和多糖含量的变化,结果表明微绿球藻比原甲藻有更强的抗紫外辐射能力.它的叶绿素a含量在UV照射下保持相对稳定,而原甲藻的叶绿素a含量明显下降.同时发现微绿球藻中的类胡萝卜素含量有十分显著的上升,由于类胡萝卜素具有保护功能,因此它很可能保护了叶绿素a免遭破坏,从而在微绿球藻的抗紫外辐射中起到重要作用.另外,紫外处理也促进了微绿球藻中多糖含量的升高,这也有利于提高它的抗UV能力,多糖可能作为一种保护机制,对保护藻类防止UV伤害方面有一定功能.原甲藻则因为这些机能较弱,对UV的抗性较低.     

两种黄精多糖衍生物的制备及其抗病毒活性比较研究

从传统中药黄精属的两个种中分别提取到两种小分子粗多糖（ＰＤ,ＰＰ）,用吡啶－氯磺酸法分别制取到这两种粗多糖的硫酸酯（ＰＤＳ,ＰＰＳ）。产物经红外、紫外鉴定,证实多糖羟基上连上了硫酸基。用离子交换,凝胶色谱提纯得到这两种粗多糖的纯化产物（ＲＰＤ,ＲＰＰ）。体外实验研究了这６种物质对非洲绿猴肾细胞（Ｖｅｒｏ）的细胞毒性和抗单纯疱疹病毒２型（ＨＳＶ－Ⅱ）的活性。结果表明,粗多糖ＰＰ的细胞毒性是由其中的杂     

应用超滤技术提取坛紫菜多糖的研究

以截留分子量为50 KD的超滤膜对坛紫菜粗多糖提取液进行超滤分离。结果表明,超滤对坛紫菜粗多糖提取液具有较好的脱色效果,脱色率达91.65%。超滤技术能很好地保留坛紫菜粗多糖中的生理活性物质,浓缩了坛紫菜粗多糖提取物,使粗多糖中总糖含量从超滤前的34.95%提高到52.07%,明显提高了坛紫菜粗多糖的糖含量,同时进一步纯化了样品。     

基于微孔板的高通量筛选6-羟基烟酸转化菌方法的建立

建立了一种基于96孔板-酶标仪的双波长紫外分光光度法高通量筛选6-羟基烟酸转化菌的方法.实验以251nm为测定波长、231nm为参比波长测定转化样品的6-羟基烟酸含量,6-羟基烟酸与△A251-231在0.5～11 μg/mL浓度范围内有良好的线性关系,服从朗伯-比尔定律,平均回收率为99.11%～100.81%.利用96孔板-酶标仪,每天筛选量可达到2000～5000个反应,达到高通量筛选要求.     

海金沙草多糖分离纯化及空间结构初步研究

为了获得纯化多糖并对其空间结构进行研究,用煎煮法从海金沙草中提取水溶性粗多糖,考察了Savage法、TCA法、单宁法等方法对提取液中蛋白质去除率和多糖回收率的影响,用乙醇沉淀法获得精制多糖,紫外光谱扫描分析多糖纯度,刚果红结合实验分析多糖空间构象.结果表明,以TCA法蛋白质去除率和多糖回收率较高.紫外扫描图谱显示,纯化...     

裂褶多糖的羧甲基化

采用氢氧化钠-氯乙酸反应体系,以异丙醇为溶剂,利用L9(34)正交试验合成mg级的不同取代度(DS)的羧甲基化裂褶多糖。研究表明试验条件下各因素对DS值影响由大到小的顺序为:氯乙酸/裂褶多糖(g/g)>氢氧化钠/裂褶多糖(g/g)>反应时间>反应温度。其红外光谱在1600 cm-1出现-COO-特征吸收;其紫外光谱在200~300 nm没有明显的吸收峰。对其13C NMR化学位移进行了归属。     

对应分析在近红外有效波长选择的应用

针对分立波长型近红外判别仪器开发过程中遇到的组合波长优选问题,提出一种基于对应分析的有效波长选择方法.对11种蘑菇样品及其在701-2500nm的光谱信息作对应分析,在对应图上计算各样品点与波长点的距离后,首先由各样品点的最近距离波长点确定出最稳健波长组合,在此基础上,对各样品点的前10、50、200个最近距离波长点进行优选,得出用921nm、1376nm、1424nm、1720nm、2233nm、2454nm这6个波长建立的SVM模型,能在输入变量最少的情况下达到用最稳健波长组合所建模型的预测能力.     

音乐治疗效应的动物实验研究

近年来国内外关于音乐治疗效应的动物实验研究认为：音乐能影响动物的情绪;音乐还对动物的免疫功能、学习及记忆能力、以及动物的神经系统结构和功能等均有一定影响。该领域的研究有利于深入探索音乐疗法的作用机理。     

Time on task effects on safety

Reviewing the literature on time on task effects on safety shows contradictory evidence, especially with regard to 12 h shifts. It is argued that this might depend on methodological problems associated with the analysis of accident data, e.g. selectivity of samples, validity of data bases and study designs, especially for analyses at the company level. Analyses of aggregated data seem to indicate an exponential increase of accident risk with time on task beyond the normal working day. This is supported by some recent studies based on data from the Federal Republic of Germany.     

Perspectives on hair evolution based on some comparative studies on vertebrate cornification

Hair evolution contributed to the biological success of mammals. Hair origin from synapsid scales is speculative and requires extensive modifications of the morphogenetic process transforming lens-shaped dermis of scales into small dermal papillae in hair. Hair evolution from glands is hypothetical but is supported from studies on the signaling control of hair vs. glandular morphogenesis. Based on immunocytochemical and comparative studies, it is hypothesized that the onion-like organization of hair derived from glandular pegs which central part produced lipids and some keratin. In a following stage, involucrin, trichohyalin, and keratins were produced in the central cells of the gland and formed a solid medulla surrounded by keratinocytes of the inner root sheath. The origin of this protohair was possibly related to increased concentration of beta-catenin and other signaling molecules in epithelial cells following the evolution of a dermal papilla. The latter activated the keratogenic genes, already utilized in cells of the claws, in concentric layers of cells of the glandular peg. Lipidogenic genes were depressed. As new genes evolved in the genome of synapsids, new circular layers of keratinocytes containing specialized hard keratins and keratin-associated proteins were formed around medullary cells. The new keratinocytes probably originated the cortex separating medulla from the external cells that became the inner root sheath. The hypothesis indicates that in a following stage, the medulla was obliterated or replaced by cortical cells while the external part of the cortex formed a cuticular surface due to the different growth rate with inner root sheath cells.     

热带气旋对红树林的影响研究进展——基于文献计量分析

红树林在防风消浪、促淤保滩、固岸护堤等方面发挥重要的作用,是抵御台风、风暴潮、海岸侵蚀等自然灾害的重要天然屏障。热带气旋是红树林面临的最主要自然威胁之一,削弱了红树林对自然灾害的抵御及生物多性维持等功能发挥。然而,尽管热带气旋对红树林的影响日益受到全球的广泛关注,但缺乏对该领域研究进展的系统分析和总结。以Web of science核心集数据库为数据源,利用CiteSpace软件对1995—2021年间热带气旋对红树林影响研究进行文献计量分析和可视化图谱绘制,以厘清该领域研究的现状、趋势和热点,并揭示未来的发展方向。研究表明：（1）该领域研究年发文量随时间处于波动上升的趋势,尤其2013年后迅速增加,表明该领域的研究日益受到重视;（2）美国、澳大利亚和印度等国家在该领域的研究走在前列,美国的中介中心性最高,其次是德国,美国广泛地与德国、法国、日本等许多国家有密切合作;（3）美国佛罗里达、加勒比地区、澳大利亚北部和印度南部等是当前研究的热点区域;（4）研究热点随时间推移而不断发展,从红树林植被的干扰损害逐渐发展到固碳储碳、海岸防护等功能的影响。全球变化背景下热带气旋对红树林的影响、红树林对热带气旋干扰的弹性、基于遥感和大数据处理的模型模拟等日益受到关注,量化热带气旋对红树林功能的影响、探明热带气旋与海平面上升的关系及对红树林影响、构建完善的观测体系数据集等将是未来研究的重要方向。研究对长期关于热带气旋对红树林影响的研究进展进行定量和可视化分析,可为预测热带气旋对红树林的影响和风险、及减缓和应对其风险等研究提供借鉴参考。     

Studies on Biosynthesis on Biotin by Microorganisms

The accumulation of biotin-vitamers in the culture media of a large number of microorganisms (about 700 strains) was studied. The contents of the biotin-vitamers were quantitatively determined by microbiological assays with Lactobacillus arabinosus and Saccharomyces cerevisiae.

It was found that large amounts of biotin-vitamers were accumulated by various microorganisms such as Streptomyces, molds and bacteria, and that the yield of biotin-vitamers was enhanced by the addition of pimelic acid or azelaic acid to the media. It was also found that the main portion of the vitamers accumulated by many microorganisms did not support the growth of Lactobacillus arabinosus, while it did support that of Saccharomyces cerevisiae. The small amounts of true biotin were observed in the culture media of various Streptomyces and molds, but hardly in the culture media of bacteria.

The identification of biotin-vitamers accumulated by various microorganisms is described, and the distribution of the vitamers in microorganisms is also described.

The results presented in this paper show that the main component of the vitamers accumulated by many microorganisms is identified as desthiobiotin by anion exchange column chromatography, paper chromatography and chemical analysis. Small amounts of fraction B (unidentified vitamers) and Fraction D (biotin) were also detected in the culture media of various molds and Streptomyces. However, these fractions were not observed in the culture media of any bacteria tested.

It was also found that large amounts of an unknown biotin-vitamer was accumulated by various bacteria. The vitamer was avidin-uncombinable, and, from the paper electrophoretic studies, it was assumed that the vitamer might be an analogue of pelargonic acid.