Koch A L, Blumberg G
Biophys J. 1976 May;16(5):389-405. doi: 10.1016/S0006-3495(76)85696-2.
Cells in different parts of the cell cycle can be separated by brief centrifugation in a density stabilized gradient: the Mitchison-Vincent technique. The position of a cell in the tube depends upon its size, shape, and density, upon the gradients of density, viscosity, and centrifugal force through which it sediments, and upon time. A program to compute the velocities and integrate the velocity profile for particles of a particular size class is presented. Because enteric bacteria are a form intermediate between right cylinders and prolate ellipsoids of revolution, the program uses values for the frictional coefficient intermediate between those calculated for ellipsoids and for cylinders. The formula f=6pietab(a/b)1/2 possesses this property and because of its simplicity greatly speeds the calculations. A second program computes the distribution of masses and then of sedimentation constants for a bacterial population, expressed either as a frequency distribution or as total mass per s-class. The effect of the known variation in cell size at division is included in these calculations, which apply to organisms undergoing balanced, asynchronous growth in which mass increase is proportional to cell size. The two programs in conjunction compute the mass or cell-number profile in an arbitrary gradient. The programs have been used to design gradients to maximize the resolution of the technique.
即米奇森 - 文森特技术。细胞在管中的位置取决于其大小、形状和密度，取决于其沉降所经过的密度、粘度和离心力梯度，还取决于时间。本文给出了一个程序，用于计算特定尺寸类别的颗粒的速度并整合速度分布。由于肠道细菌是介于直圆柱体和长旋转椭球体之间的一种形态，该程序使用的摩擦系数值介于为椭球体和圆柱体计算的值之间。公式(f = 6\pi\eta ab(a/b)^{1/2})具有此特性，并且由于其简单性大大加快了计算速度。第二个程序计算细菌群体的质量分布，然后计算沉降常数分布，可表示为频率分布或每s类别的总质量。这些计算中考虑了已知的细胞分裂时大小变化的影响，适用于经历平衡、异步生长且质量增加与细胞大小成比例的生物体。这两个程序结合起来可计算任意梯度中的质量或细胞数分布。这些程序已用于设计梯度以最大化该技术的分辨率。
