Wessels D, Murray J, Soll D R
Department of Biology, University of Iowa, Iowa City 52242.
Cell Motil Cytoskeleton. 1992;23(2):145-56. doi: 10.1002/cm.970230207.
The instantaneous velocity plots of Dictyostelium discoideum amoebae responding to natural waves and simulated temporal waves of cAMP with periods of 7 min are highly similar. This similarity has been used to deduce the dynamics of a natural wave crossing an amoeba, and the behavior of amoebae has been characterized during the different phases of a natural wave with a computer-assisted dynamic image analyzing system. During the first approximately 150 sec of the front of a natural wave, cells move persistently toward the aggregation center, with high instantaneous velocity and a decreased frequency of lateral pseudopod formation. During the last 30 sec of the front of the wave and the first 30 sec of the back of the wave, there is a "freeze" in cell shape and a dramatic depression in cell motility, pseudopod formation, and intracellular particle movement. During the last 180 sec of the back of the wave, there is a rebound in pseudopod formation, but it is random in direction and leads to no net cellular translocation. The data suggest that all of the behavior of a cell but orientation during the translocation phase is mediated by the temporal dynamics of the wave. The data also suggest that orientation toward the aggregation center occurs early in the front of the wave and that, once oriented, cells move in a blind fashion during the translocation phase.
盘基网柄菌变形虫对周期为7分钟的自然波和模拟cAMP时间波的瞬时速度图高度相似。这种相似性已被用于推断自然波穿过变形虫的动力学，并且使用计算机辅助动态图像分析系统对变形虫在自然波不同阶段的行为进行了表征。在自然波前沿的大约前150秒内，细胞持续朝着聚集中心移动，瞬时速度高，侧向伪足形成频率降低。在波前沿的最后30秒和波后沿的前30秒内，细胞形状“冻结”，细胞运动性、伪足形成和细胞内颗粒运动急剧下降。在波后沿的最后180秒内，伪足形成出现反弹，但方向是随机的，不会导致细胞净移位。数据表明，细胞在移位阶段除定向外的所有行为均由波的时间动态介导。数据还表明，朝着聚集中心的定向在波前沿早期发生，并且一旦定向，细胞在移位阶段以盲目方式移动。
