A METHOD FOR THE QUANTITATIVE DETERMINATION OF TRYPSIN AND PEPSIN

A quantitative method is described which permits a determination of the relative amount of trypsin or pepsin present in a gelatin-enzyme digestion mixture, provided the gelatin and trypsin solutions are purified. This method is dependent upon the change in viscosity of such solutions. It is found that the time required to cause a given percentage change in the viscosity is nearly inversely proportional to the amount of enzyme present. It is pointed out that the particular value of the method lies in the fact that enzyme reactions which take place in the presence of "buffer" salts may be studied.     

A METHOD FOR THE QUANTITATIVE AND QUALITATIVE DETERMINATION OF PLANKTONIC DIATOMS

SUMMARY

A method for the quantitative and qualitative determination of planktonic diatoms was developed. The method uses the Utermöhl counting technique (in which an inverted microscope is employed) as a basis but also involves the calculation of the relative density of each species in the association (as determined with the ordinary light microscope). A combination of the results thus obtained ensures that even the smallest diatoms (2,5 μm) are accounted for. These often constitute a significant proportion of the population, but are often overlooked or may not even be resolved using Utermöhl's method.     

对分子置换法中积分半径选取方法的探讨

通过对晶胞中帕特逊向量的统计分布的研究,从理论上阐述了根据模型结构单元的线度确定旋转函数的积分半径这种作法的合理性,并且指出了估算积分半径取值范围的具体方法,以及自身旋转函数与交叉旋转函数的积分半径取值范围的区别。经过我们将此方法应用于酚胰岛素Ｂ链羰端六肽胰岛素的旋转函数求解,计算结果证实了这种积分半径的估算方法的可靠性。     

浮游植物叶绿素与脱镁叶绿素的测定方法

叶绿素含量的测定,早已受到生理学家的重视。在生态学范畴内,浮游藻类的叶绿素含量既是浮游藻类现存量的一个指标,又是推算浮游藻类生产量的重要参量。故生态学家、水产与环境科学工作者,均日益重视叶绿素含量的测定。本文在综合国内外有关资料的基础上,结合作者的工作经验,对浮游藻类的光合色素组成、叶绿素与脱镁叶绿素的测算原理、测算方法作了详细介绍。     

A NEW METHOD FOR THE STUDY OF DIFFUSION OF BIOLOGICALLY ACTIVE MATERIAL

A simple diffusion apparatus has been described in which a layer of solution is allowed to diffuse upward into a layer of solvent. Accurate sampling is performed at various heights and the concentration of the samples is determined. The method has been illustrated with a determination of the diffusion constant of crystalline catalase, which was found to be 3.1 x 10^–7 cm.²/sec. at 4°C. The method should be especially suited to the study of biological substances endowed with specific activity and which cannot be obtained in pure solution.     

A NEW METHOD FOR THE DETERMINATION OF OSMOTIC PRESSURE

Lockhart , James A. (California Inst. Tech., Pasadena.) A new method for the determination of osmotic pressure. Amer. Jour. Bot. 46(10): 704–708. Illus. 1959.—A new method for the determination of osmotic pressure in appropriate plant tissues is described. This method is based on the observation that the degree of deformability of tissue equilibrated in hypertonic solution is a linear function of the extent by which the external osmotic pressure exceeds the osmotic pressure of the cell contents. Extrapolation of the deformability vs. external osmotic pressure to zero deformation yields, then, the osmotic pressure of the tissue at limiting plasmolysis. It is shown that the osmotic pressure determinations are independent of incubation time and magnitude of applied force. A simple device is described for measuring bending throughout a wide range of angles, while keeping the applied force constant.     

树鼩血红蛋白正常值测定

本文报道了30只产于我国云南的成年树鼩(Tupaia belangeri chinensis)的血红蛋白正常值。结果如下:抗碱血红蛋白均数(％)为0.90±0.09,HbF细胞均数(％)0.10±0.05,Heinz小体生成率均数(％)为12.35±0.81,热变性血红蛋白均数(％)为2.48±0.35,血红蛋白溶解度均数(％) 为83.58±1.12。异丙醇试验为阴性,未见H包涵体。上述结果与人的血红蛋白正常值进行了分析比较。血红蛋白的醋酸纤维素薄膜电泳显示了树鼩Hb的五个区带,树鼩Hb的电泳迁移率慢于人的Hb。     

从灰分及氮含量计算鱼体能量含量的一个简易方法

鱼体能量含量的测定是鱼类能量学研究的一个重要内容1。近来的研究表明,测定鱼体能量含量上的误差,是造成估算鱼类能量收支误差的一个重要原因3。测定生物能量含量的最可靠的方法为用热量计(calorimeter)直接测定。但热量计价格昂贵,不易普及;测量中需用铂丝作引燃材料,成本较高;热量计的操作也较费时。       

水生植物生产量测定的种群统计学方法

以Ａｌｌｅｎ曲线法为例,介绍了水生植物生产量测定的种群统计学方法的原理,并以同龄群的指数增长,与死亡模型为基础,得出了同龄群生产量的计算公式,以湖北斧头湖菰群落的调查数据为例计算了菰的生产量。     

THE DETERMINATION OF THE EQUIVALENT WEIGHT OF PROTEINS

The magnitude of the correction in the fifth column of Table III may be open to some doubt, as are all corrections of such a character, and the significance of the above experiment in the author''s mind lies not so much in the actual magnitude of the values given in the last column of this table as in their comparative magnitudes. For this reason the entire experiment reported was performed in a single session using the same gelatin solution, so that, whatever the magnitude of the correction, it would be the same in all cases. Actually the results in the case of the acid titrations are in fair agreement with those of Hitchcock (8). In the present experiment it is seen that, within the limits of experimental error, one gets the same value for the number of cc. of tenth normal acid bound by 1 gm. of gelatin whether one titrates with the acid or with the gelatin. In the case of the base there is a small difference, due probably to carbon dioxide, but this effect is in a direction opposite to that which one would expect on the assumption that it is due to appreciable adsorption. From this it is concluded that the binding due to adsorption in the case of gelatin is not significant compared to that due to chemical neutralization. The author realizes that gelatin is a poor choice for a basis of generalizations, and similar work is at present in progress on various other proteins. He does feel, however, that the conclusions of Hoffman and Gortner from their work on the prolamines may also be too widely generalized, and that, on the whole, the acid or alkali bound by adsorption in the case of proteins will not constitute the large majority of the total amounts bound, though certainly one will expect a certain amount of such binding in all cases. It also seems that before placing undue emphasis on the conclusions of these workers the possibilities of equivocal results due to specific technique should be considered. This technique consisted in introducing weighed amounts of dry protein into a definite volume of standard acid or base at the equilibrium temperature, in general, and, "after about 15 minutes, during which time the flask was shaken several times," determining the pH of the equilibrium solution. Is it possible that the actual speed of solution of the protean is such that, even though reproducible results are obtained using identical technique, actual equilibrium conditions are approached only when comparatively high concentrations of acid or alkali are employed, in which cases the solution velocity of the protein may he expected to be greater, other factors remaining constant?