PDF(Pubmed)
Abstract：
Gliding motility proceeds with little changes in cell shape and often results from actively driven surface flows of adhesins binding to the extracellular environment. It allows for fast movement over surfaces or through tissue, especially for the eukaryotic parasites from the phylum apicomplexa, which includes the causative agents of the widespread diseases malaria and toxoplasmosis. We have developed a fully three-dimensional active particle theory which connects the self-organized, actively driven surface flow over a fixed cell shape to the resulting global motility patterns. Our analytical solutions and numerical simulations show that straight motion without rotation is unstable for simple shapes and that straight cell shapes tend to lead to pure rotations. This suggests that the curved shapes of Plasmodium sporozoites and Toxoplasma tachyzoites are evolutionary adaptations to avoid rotations without translation. Gliding motility is also used by certain myxo- or flavobacteria, which predominantly move on flat external surfaces and with higher control of cell surface flow through internal tracks. We extend our theory for these cases. We again find a competition between rotation and translation and predict the effect of internal track geometry on overall forward speed. While specific mechanisms might vary across species, in general, our geometrical theory predicts and explains the rotational, circular, and helical trajectories which are commonly observed for microgliders. Our theory could also be used to design synthetic microgliders.
摘要：
滑翔运动的细胞形状几乎没有变化，通常是由于与细胞外环境结合的粘附素的主动驱动表面流动所致。它允许在表面或组织中快速移动，特别是对于来自顶孔门的真核寄生虫，其中包括广泛传播的疟疾和弓形虫病的病原体。我们开发了一个完全三维的活动粒子理论，它连接了自组织，在固定的细胞形状上主动驱动表面流动到最终的全局运动模式。我们的解析解和数值模拟表明，对于简单的形状，没有旋转的直线运动是不稳定的，并且笔直的细胞形状往往会导致纯旋转。这表明疟原虫子孢子和弓形虫速殖子的弯曲形状是进化适应，以避免旋转而不翻译。某些粘细菌或黄细菌也使用滑翔运动，主要在平坦的外表面上移动，并且对通过内部轨道的细胞表面流量有更高的控制。我们为这些案例扩展了我们的理论。我们再次发现旋转和平移之间的竞争，并预测内部轨道几何形状对整体前进速度的影响。虽然具体机制可能因物种而异，总的来说,我们的几何理论预测和解释了旋转，圆形,以及微滑翔机通常观察到的螺旋轨迹。我们的理论也可以用来设计合成的小滑翔机。
