Department of Cell Biochemistry, University of Groningen, AG, Groningen, the Netherlands.
Methods Mol Biol. 2024;2828:185-204. doi: 10.1007/978-1-0716-4023-4_14.
Amoeboid cells such as the protist Dictyostelium, human neutrophils, and the fungus B.d. chytrid move by extending pseudopods. The trajectories of cell movement depend on the size, rhythm, and direction of long series of pseudopods. These pseudopod properties are regulated by internal factors such as memory of previous directions and by external factors such as gradients of chemoattractants or electric currents. Here a simple method is described that defines the X, Y time coordinates of a pseudopod at the start and the end of the extension phase. The connection between the start and end of an extending pseudopod defines a vector, which is the input of different levels of analysis that defines cell movement. The primary information of the vector is its spatial length (pseudopod size), temporal length (extension time), extension rate (size divided by time), and direction. The second layer of information describes the sequence of two (or more) pseudopods: the direction of the second pseudopod relative to the direction of the first pseudopod, the start of the second pseudopod relative to the extension phase of the first pseudopod (the second starts while the first is still extending or after the first has stopped), and the alternating right/left extension of pseudopods. The third layer of information is provided by specific and detailed statistical analysis of these data and addresses question such as: is pseudopod extension in buffer in random direction or has the system internal directional memory, and how do shallow external electrical or chemical gradients bias the intrinsic pseudopod extension. The method is described for Dictyostelium, but has been used successfully for fast-moving neutrophils, slow-moving stem cells, and the fungus B.d. chytrid.
变形细胞，如原生动物 D.dictyostelium、人类中性粒细胞和真菌 B.d. chytrid，通过延伸伪足运动。细胞运动的轨迹取决于长串伪足的大小、节奏和方向。这些伪足特性受内部因素（如对先前方向的记忆）和外部因素（如趋化因子或电流梯度）的调节。这里描述了一种简单的方法，用于定义延伸阶段开始和结束时伪足的 X、Y 时间坐标。延伸伪足的起点和终点之间的连接定义了一个向量，这是定义细胞运动的不同层次分析的输入。向量的主要信息是其空间长度（伪足大小）、时间长度（延伸时间）、延伸率（大小除以时间）和方向。信息的第二层次描述了两个（或更多）伪足的序列：第二个伪足相对于第一个伪足的方向、第二个伪足相对于第一个伪足延伸阶段的起点（第二个开始时第一个仍在延伸或第一个已经停止），以及伪足的交替右/左延伸。信息的第三层是通过对这些数据进行特定和详细的统计分析提供的，解决了诸如：伪足在缓冲液中的延伸是否是随机方向的，还是系统内部有定向记忆，以及浅的外部电或化学梯度如何使内在的伪足延伸产生偏差等问题。该方法已用于 D.dictyostelium，但也已成功用于快速运动的中性粒细胞、缓慢运动的干细胞和真菌 B.d. chytrid。
