Kroeger Jens H, Daher Firas Bou, Grant Martin, Geitmann Anja
McGill University, Montréal, Québec, Canada.
Biophys J. 2009 Oct 7;97(7):1822-31. doi: 10.1016/j.bpj.2009.07.038.
The dynamics of cellular organelles reveals important information about their functioning. The spatio-temporal movement patterns of vesicles in growing pollen tubes are controlled by the actin cytoskeleton. Vesicle flow is crucial for morphogenesis in these cells as it ensures targeted delivery of cell wall polysaccharides. Remarkably, the target region does not contain much filamentous actin. We model the vesicular trafficking in this area using as boundary conditions the expanding cell wall and the actin array forming the apical actin fringe. The shape of the fringe was obtained by imposing a steady state and constant polymerization rate of the actin filaments. Letting vesicle flux into and out of the apical region be determined by the orientation of the actin microfilaments and by exocytosis was sufficient to generate a flux that corresponds in magnitude and orientation to that observed experimentally. This model explains how the cytoplasmic streaming pattern in the apical region of the pollen tube can be generated without the presence of actin microfilaments.
细胞器的动态变化揭示了有关其功能的重要信息。生长中的花粉管中囊泡的时空运动模式受肌动蛋白细胞骨架控制。囊泡流动对于这些细胞的形态发生至关重要，因为它确保了细胞壁多糖的靶向递送。值得注意的是，靶区域不含太多丝状肌动蛋白。我们以扩张的细胞壁和形成顶端肌动蛋白边缘的肌动蛋白阵列作为边界条件，对该区域的囊泡运输进行建模。通过施加肌动蛋白丝的稳态和恒定聚合速率获得边缘的形状。让囊泡进出顶端区域的通量由肌动蛋白微丝的方向和胞吐作用决定，足以产生在大小和方向上与实验观察到的通量相对应的通量。该模型解释了在没有肌动蛋白微丝的情况下，花粉管顶端区域的细胞质流动模式是如何产生的。
