蜂毒素与紫膜的相互作用机理研究──与三种表面活性剂的比较

用吸收光谱和圆二色谱的方法研究了蜂毒素与嗜血菌紫膜的相互作用机理．通过与三种在结构和电荷上不同的表面活性剂与紫膜的作用相比较,可以年出蜂毒作为带正电荷的分子与同样带正电的表面活性剂ＤＴＡＢ在引起紫膜凝聚方面表现相同;但在对紫膜可见光区的吸收光谱和圆二色谱的影响上却与具有刚性结构的ＣＨＡＰＳ相似,表明蜂毒可在紫膜表面以一种刚性较大的构象（如α螺旋）存在,不能进入膜蛋白流水区的深层．另外,从紫膜－Ｔｒｉｔｏｎ－蜂毒混合作用体系的研究中得到如下推测：蜂毒与Ｔｒｉｔｏｎ竞争菌紫质分子周围的结合位点,可排斥位于菌紫质周围的Ｔｒｉｔｏｎ分子．表明蜂毒具有比Ｔｒｉｔｏｎ更强的与菌紫质的亲和力,从而提供了支持蜂毒分子存在与膜蛋白－菌紫质的直接相互作用的有力证据．     

天花粉蛋白与FMP复合物的晶体结构

用浸泡法得到了天花粉蛋白（ＴＣＳ）与ＦＭＰ复合物的晶体,在ＳＩＭＥＮＮＳＸ－２００Ｂ面探测器系统上收集了一套２．０分辨率的Ｘ射线衍射数据。用同晶差值傅立叶法解析了复合物的结构,经Ｘ—ＰＬＯＲ程序修正得到了ＴＣＳ—ＦＭＰ复合物的分子结构并找出了１９７个水分子,最后的Ｒ因子为０．１７２,键长和键角的ＲＭＳ偏差分别为０．０１５和２．９２２度。ＴＣＳ—ＦＭＰ复合物中,ＦＭＰ与天花粉蛋白分子有较好的结合,其结合位置正处于根据三维结构和突变体信息推测的Ｎ一糖苷酶活性口袋之中。它的类嘌呤环夹在Ｙ７０和Ｙ１１１两个侧链环之间,与Ｙ７０环近乎平行,其Ｎ７和Ｎ６分别与ＴＣＳ分子的Ｇ１０９４羰基氧和Ｉ７１的Ｎ成氢键,Ｎ３靠近Ｒ１６３的侧链,其磷酸根则伸向活性口袋的底部,与Ｅ１８９、Ｅ１６０和Ｒ１６３等残基作用。     

The influence of the type of contraction on the masseter muscle EMG power spectrum

Different behaviours of the EMG power spectrum across increasing force levels have been reported for the masseter muscle. A factor that could explain these different behaviours may be the type of contraction used, as was recently shown for certain upper limb muscles⁵. The purpose of this study was to compare, between two types of isometric contractions, the behaviour of EMG power spectrum statistics (median frequency (MF) and mean power frequency (MPF)) obtained across increasing force levels. Ten women exerted, while biting in the intercuspal position, three 5 s ramp contractions that increased linearly from 0 to 100% of the maximal voluntary contraction (MVC). They also completed three step contractions (constant EMG amplitude) at each of the following levels: 20, 40, 60 and 80% MVC. EMG signals from the masseter muscle were recorded with miniature surface electrodes. The RMS, as well as the MPF and MF of the power spectrum were calculated at 20, 40, 60 and 80% MVC for each type of contraction. As expected, the RMS values showed similar increases with increasing levels of effort for both types of contractions. Different behaviours for both MPF (contraction^*force interaction, ANOVA, P<0.05) and MF (contraction^*force interaction, ANOVA, P>0.05) across increasing levels of effort were found between the two types of contraction. The use of step contractions gave rise to a decrease of both MPF and MF with increasing force, while the use of ramp contractions gave rise to an increase in both statistics up to at least 40% MVC followed by a decrease at higher force levels. These findings suggest that the type of contraction used does influence the behaviour of the spectral statistics across increasing force levels and that this could explain the differences obtained in previous studies for the masseter muscle.     

Preservation and computer-aided microscopic analysis of planktonic Protozoa and algae

Samples of microplankton and larger nanoplankton (5 to 200 m) are preserved with a combination of Lugol's solution and DaFano's fixative. Organisms are then settled on a gelatin-coated slide, dried and embedded in 40 percent glycerin. Counting and sizing is performed under a microscope using a drawing tube, which facilitates measuring the organisms with a microcomputer-interfaced caliper. An interactive computer program, written in BASIC, allows for estimating the volumes of cells in up to 40 shape/species categories. The program then saves data on a disk, retrieves them, and calculates the results either for individual species (abundance, biomass, and mean cell volume) or as a pooled size spectrum of all organisms measured.     

别藻蓝蛋白藻蓝胆素发色团分子构象研究

主要研究了蓝绿藻污棕席藻(Phormidium luridum)别藻蓝蛋白在不同 pH值条件下的吸收光谱和共振拉曼光谱.发现低聚化的结果导致了三聚体别藻蓝蛋白 650nm 特征吸收峰的消失和一些共振拉曼带强度和位置的移动.结果表明在低 pH 值作用下的低聚化的别藻蓝蛋白中藻蓝胆素发色团分子的构象和自由胆素分子类似,比三聚体的别藻蓝蛋白的发色团分子更趋于卷曲,折叠的构象态.而三聚体的别藻蓝蛋白,主要的拉曼带 1645cm^-1是其发色团分子构象处于更线性延展的标志,其光谱行为和吸收光谱 A_vis/A_uv所表征的发色团分子构象的结果相一致.     

聚球藻(Synechococcus leopoliensis625)藻胆体-类囊体膜光化学活性和亚显微结构的研究

聚球藻藻胆体-类囊体膜吸收光谱中有五个吸收峰,它们位于420nm,438nm,490nm,624nm 和678nm。放氧速率为161—179mol O2/mg Chl.hr.电镜照片中显示在类囊体膜上有大量藻胆体。     

油麻藤凝集素的荧光光谱研究

用化学修饰、内源荧光和荧光淬灭等方法研究了油麻藤凝集素（ＭＳＬ）的溶液构象变化和微环境的构象特征。研究发现ＭＳＬ分子中总共有９个色氨酸（Ｔｒｐ）残基,它们的荧光能被丙烯酰胺淬灭,但不易为ＫＩ接近而淬灭,ＭＳＬ经Ｎ－溴代琥珀酰亚胺（ＮＢＳ）修饰后,其内源性荧光发射谱发生相应变化,结果表明ＭＳＬ分子中部分Ｔｒｐ残基埋藏于分子内部,而位于分子表面的Ｔｒｐ残基可能处于分子的疏水袋中。     

高原鼠兔与达乌尔鼠兔食物资源维生态位的研究

作者于１９９３年在青海省刚察县年诺索玛地区发现高原鼠兔（Ｏｃｈｏｔｏｎａ ｃｕｒｚｏｎｉａｅ）和达乌尔鼠兔（０．ｄａｕｒｉｃａ）在布哈河谷二阶同域且重叠分布之现象,并从这两种鼠兔的食物资源利用出发,研究了其生态位关系问题。在食物资源维上的生态位宽度（ＰＳ）,高原鼠兔为０．４７４４,达乌尔鼠兔为０．４９６４,即它们具有相近似的生态位宽度。这两种动物的生态位在食物资源谱维上的重叠值（ＦＴ）为０．８０９     

细胞色素bc_1复合物的喇曼光谱研究

对提纯的细胞色素ｂｃ１复合物的氧化态和底物琥珀酸还原态两个样品进行了共振喇曼和富立叶喇曼光谱测定和比较。琥珀酸还原态与氧化态的共振谱比较明显有变化,而富立叶红外谱没有什么差别。说明呼吸链的电子传递体在氧化态与还原态交替变化进行电子传递时,蛋白总体构象不发生大的改变,而活性中心血红素辅基局部构象变化很大。