一种测量细胞面积的显微光度方法

细胞生物学研究中广泛应用显微分光光度计测定单个细胞中特定物质的含量。通常在测含量的同时还要求获得单个细胞内此种物质分布的面积。对形状规则的被测物质,一般常用目镜测微尺测出长度,再算出面积。但这种方法不仅费时,费力,而且不适于测量形状不规则的单个细胞。我们在采用双区法,在测量物质含量的同时,可以很方便地测出不规则形状细胞內被测物质所占的面积。显微分光光度计测量物质含量的方法中常用的有两种——双区法和双波法。在公式推导中有一项被测物面积:B(1-F),其中(1-F)是测量光阑面积中含有被测物部份所占的百分数,B是测量光阑面积。在双区法中(1-F)=(1-T)/(1-T~*)(其中T~*是测量     

一种测量细胞面积的显微光度方法

细胞生物学研究中广泛应用显微分光光度计测定单个细胞中特定物质的含量。通常在测含量的同时还要求获得单个细胞内此种物质分布的面积。对形状规则的被测物质,一般常用目镜测微尺测出长度,再算出面积。但这种方法不仅费时,费力,而且不适于测量形状不规则的单个细胞。我们在采用双区法,在测量物质含量的同时,可以很方便地测出不规则形状细胞内被测物质所占的面积。显微分光光度计测量物质含量的方法中常用的有两种——双区法和双波法。在公式推导中有一项被测物面积:B(1—F),其中(1—F)是测量光阑面积中含有被测物部份所占的百分数,B是测量光阑面积。     

苹果果实表面积的一种新测算方法

本文提出一个描述苹果果实的数学模型，基于此模型推导出计算苹果果实表面积的新方法．只需测知果实纵径、横径、梗洼深和萼洼深，即可利用新方法计算出果实表面积，且测算精度高，其平均测算误差仅约1.5％．     

一种从酵母细胞中提取组蛋白的方法

为了制备体外酵母DNA序列组装核小体所需的组蛋白,利用酸抽提方法从未经饥饿处理和经过不同时间饥饿处理的酿酒酵母细胞中分离组蛋白,经SDS-PAGE电泳分析和Bradford法测定蛋白浓度,发现抽提物中含有组蛋白H1、H2A、H2B、H3和H4,电泳条带位置正确、纯度较高,正常细胞的抽提物中蛋白总量达到158 μg/mL.试验结果表明该方法可以提取出较高质量的酿酒酵母组蛋白.     

一种改良的细胞计数方法

库尔特计数器(Coulter Counter)是国内实验室较为常用的仪器,多用于血细胞计数,也可做其它细胞或颗粒的计数。库尔特计数器工作的基本原理是将需要计数的颗粒或细胞悬浮在可导电的介质溶液中,并将测定管浸于此悬浮液。测定管下端有一微孔,管内充满同种介质溶液。管的内外各有一电极(见图1)。测定时外加一定的真空度,从而迫使一定量的细胞     

一种定量分析水稻细胞过敏反应的方法

在定量分析水稻细胞过敏反应(HR)方法中,溴酚蓝染色法的效果明显优于伊文氏蓝染色法。线形回归分析显示,在0.625￣20ΜG·ML-1范围内的溴酚蓝最大光吸收值与其浓度间的相关系数为0.9994。溴酚蓝染色法优化的测定条件为:0.03%溴酚蓝染色15MIN,水洗去除未结合染料,再在50℃下用含50%甲醇和1%SDS抽提液抽提与死亡细胞结合的染料30MIN,测定抽提液光吸收值(OD595),以甲醇处理15MIN的细胞作为全杀死细胞参照。用优化方法测定的水稻细胞死亡率与实际死亡率一致。     

一种改进的杂交瘤细胞电融合方法

一种改进的杂交瘤细胞电融合方法邹翔（南京大学医学院南京２１０００８）刘琴芝,裴红英,郁文芳,安节,陈伯权（中国预防医学科学院病毒学研究所北京１０００５２）陈刚,赵南明（清华大学生物科学与技术系生物膜与膜生物工程国家重点实验室北京１０００８４）我们对国...     

显示细胞有丝分裂的一种理想方法

本文介绍一种显示植物细胞有丝分裂各个时期的方法,该方法效果明显,易于掌握,是一种较理想的实验教学方法。     

一种检测早期凋亡细胞的方法

本文介绍了一种定量检测早期凋亡细胞的流式细胞术——Annexin V-PI双染色法,并作了一些改进。     

介绍一种超薄切片中细胞定位的薄层包埋方法

电子显微技术中,对研究材料中的特定组织或细胞的定位在超薄切片时是最困难的一步。曾提出的用还氧树脂厚切片重新包埋的方法以及类似的厚切片重新粘贴法在克服这一困难上有很好的效果。对于单细胞或分离的原生质体,以及花粉和萌发的花粉管等材料,电镜样品的制作常用离心进行材料的收集、固定、脱水和渗透等步骤,并按寻常的方法     

颅骨某些角度的测量计算法

本文根据余弦定理对颅骨20项与法兰克福平面无关的角度,采用测量计算法,即用直脚规或弯脚规测量各角三个测点间的三边直线距离,将余弦定理公式输入袖珍电子计算器内,再由计算器算出角度。经实践我们认为此法具有操作简单易行、无需投影描绘仪和定颅器等设备、节约时间、精确度高和误差小等优点。     

METABOLISM OF TISSUE CULTURES : III. A METHOD FOR MEASURING THE PERMEABILITY OF TISSUE CELLS TO SOLUTES

By using radioactive isotopes in tissue cultures, the rate of permeation of substances into cells can be measured independently of concurrent metabolic reactions of these substances. Techniques of obtaining and analyzing data are described. Examples are given using radioactive potassium and phosphorus. Using cultures of chick embryo muscle, turnover time for cell potassium is 6 hours, and for cell inorganic phosphate is 7 hours in the examples cited. Permeability rates, based on estimates of the cell surface involved and expressed as millimoles per cm.² per hour, are of the order of magnitude of 10^–6 for potassium and of 10^–7 for phosphate.     

A METHOD FOR THE REMOVAL OF THE JELLY AND VITELLINE MEMBRANE FROM THE EMBRYOS OF XENOPUS LAEVIS

A simple procedure is described for removing the jelly and vitelline membrane of Xenopus laevis embryos. The method is based on the observation that incubation of the embryos in the mixed solution of trypsin and sodium thioglycolate at pH 8.0 causes effective dissolution of these structures. This solution is equally effective in this respect on the embryos at different developmental stages. Normal development is obtained from all of the denuded neurulae and from many of the denuded earlier embryos. Some chemical properties of the jelly and the vitelline membrane of Xenopus laevis are discussed based upon these observations.     

THE SYNTHESIS OF PHOSPHOLIPIDS IN THE NUCLEUS AND NUCLEAR MEMBRANE OF SYNCHRONIZED HeLa CELLS

HeLa cells were synchronized by a double thymidine block and pulse labeled at different stages of the cell cycle with ³H-choline. The specific activity of phospholipids extracted from the cell, the nucleus and the nuclear membrane showed a progressive increase from S to G₁; the incorporation of choline into phospholipids of asynchronous cells showed a specific activity intermediate between the values of S and G₁ cells. Similar results were obtained when ³²phosphorus was used as a precursor instead of choline. Thin layer chromatographic analysis of phospholipids extracted from cells in S and from cells in G₁ failed to show any difference in the distribution of radioactivity among the various phospholipid classes. Choline uptake by HeLa cells in different phases of the cell cycle did not show significant variations. However, during the synchronization process, shortly after the addition of excess thymidine, an increased uptake of choline by cells and an increased incorporation of choline into phospholipids were found. The results indicate that some of the changes occurring in phospholipids synthesis may not be cell cycle dependent, but may be the effect of the synchronizing process.     

A STOPPED-FLOW FLUORESCENCE ANISOTROPY METHOD FOR MEASURING HORMONE BINDING AND DISSOCIATION KINETICS WITH CELL-SURFACE RECEPTORS IN LIVING CELLS

ABSTRACT

We have developed a system for extending stopped-flow analysis to the kinetics of ligand capture and release by cell surface receptors in living cells. While most mammalian cell lines cannot survive the shear forces associated with turbulent, stopped-flow mixing, we determined that 32D cells, murine hematopoietic precursor cells, can survive rapid mixing, even at the high flow rates necessary to achieve dwell times as short as 10?msec. In addition, 32D cells do not express any member of the ErbB family of receptors, providing a null background for studying this receptor family. We have established a series of stable, monoclonal 32D-derived cell lines that express the epidermal growth factor (EGF) receptor, ErbB2, or a combination of both at different ratios. Using these cell lines and a homogeneous fluorescent derivative of H22Y-mEGF modified with fluorescein at the amino terminus (F-EGF), we have measured association and dissociation of F-EGF with its receptor. Association was measured by following the time-dependent changes in fluorescence anisotropy after rapidly mixing cells at various cell densities with F-EGF at 1–15?nM. Dissociation was measured both by chase experiments in which unlabeled EGF was mixed with cells pre-equilibrated with F-EGF or by dilution of cells equilibrated with F-EGF. Comparison of these dissociation experiments demonstrated that little or no ligand-induced dissociation occurs in the chase dissociation experiments. For each cell line, data from a series of association experiments and dilution dissociation experiments were subjected to global analysis using a two independent receptor-class model. Our analysis is consistent with the presence of two distinct receptor populations, even in cells bearing only the EGF receptor. Increasing the relative expression of ErbB2 leads to an increase in the fraction of high affinity class receptors observed, without altering the total number of EGF binding sites.     

滤膜法测定水中大肠菌群简便方法的研究

本研究方法为ＩＳＯ９３０８－１规定的滤膜法测定水中大肠菌群的方法,该方法操作简便只需分离和证实两步实验即可得出结果;分离培养基上的阴阳性菌落颜色分明,易于分辩;所用培养基不含致癌物质。本研究方法的准确度高,回收率的均值为９４７％,批内变异系数小于１０％,检出限为５００ｍｌ水样可检出１个ＣＦＵ,检出率是传统方法的３１倍。本研究还探讨了分离培养基的ｐＨ值对菌落颜色的影响。本研究内容经查新在国内尚无报道。