Time-lapsed films of particle motion on the leading lamella of chick heart fibroblasts and mouse peritoneal macrophages were analyzed. The particles were composed of powdered glass or powdered aminated polystyrene and were 0.5-1.0 micrometer in radius. Particle motions were described by steps in position from one frame to the time-lapse movies to the next. The statistics of the step-size distribution of the particles were consistent with a particle in Brownian motion subject to a constant force. From the Brownian movement, we have calculated the two-dimensional diffusion coefficient of different particles. These vary by more than an order of magnitude (10(-11)-10(-10) cm2/s) even for particles composed of the same material and located very close to each other on the surface of the cell. This variation was not correlated with particle size but is interpretable as a result of different numbers of adhesive bonds holding the particles to the cells. The constant component of particle movement can be interpreted as a result of a constant force acting on each particle (0.1-1.0 x 10(-8) dyn). Variations in the fractional coefficient for particles close to each other on the cell surface do not yield corresponding differences invelocity, suggesting that the frictional coefficient and the driving forcevary together. This is consistent with the hypothesis that the particlesare carried by flow of the membrane as a whole or by flow of somesubmembrane material. The utility of our methods for monitoring cell motilebehavior in biologically interesting situations, such as a chemotacticgradient, is discussed.
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机译:分析了鸡心成纤维细胞和小鼠腹膜巨噬细胞前片上的粒子运动的延时电影。颗粒由粉末玻璃或粉末胺化聚苯乙烯组成,半径为0.5-1.0微米。粒子运动通过从一帧到定时影片到下一帧的位置步进来描述。颗粒的步长分布的统计数据与布朗运动中受到恒定力的颗粒一致。根据布朗运动,我们计算了不同粒子的二维扩散系数。即使对于由相同材料组成且位于细胞表面上非常靠近的粒子,它们的变化幅度也超过一个数量级(10(-11)-10(-10)cm2 / s)。这种变化与颗粒大小无关,但是可以解释为将颗粒固定在细胞上的粘合剂数量不同。粒子运动的恒定分量可以解释为作用在每个粒子上的恒定力的结果(0.1-1.0 x 10(-8)dyn)。在细胞表面上彼此靠近的粒子的分数系数变化不会在速度,表明摩擦系数和驱动力一起变化。这与粒子的假设一致通过整个膜或某些膜的流动来承载膜材料。我们用于监测细胞运动的方法的实用性在生物学上有趣的情况下的行为,例如趋化渐变,进行了讨论。
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