Goldstein Raymond E, Tuval Idan, van de Meent Jan-Willem
Department of Applied Mathematics and Theoretical Physics and Cambridge Computational Biology Institute, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom.
Proc Natl Acad Sci U S A. 2008 Mar 11;105(10):3663-7. doi: 10.1073/pnas.0707223105. Epub 2008 Feb 29.
Found in many large eukaryotic cells, particularly in plants, cytoplasmic streaming is the circulation of their contents driven by fluid entrainment from particles carried by molecular motors at the cell periphery. In the more than two centuries since its discovery, streaming has frequently been conjectured to aid in transport and mixing of molecular species in the cytoplasm and, by implication, in cellular homeostasis, yet no theoretical analysis has been presented to quantify these processes. We show by a solution to the coupled dynamics of fluid flow and diffusion appropriate to the archetypal "rotational streaming" of algal species such as Chara and Nitella that internal mixing and the transient dynamical response to changing external conditions can indeed be enhanced by streaming, but to an extent that depends strongly on the pitch of the helical flow. The possibility that this may have a developmental consequence is illustrated by the coincidence of the exponential growth phase of Nitella and the point of maximum enhancement of those processes.
胞质环流存在于许多大型真核细胞中，尤其是植物细胞中，它是由细胞周边分子马达携带的颗粒所产生的流体夹带作用驱动细胞内容物循环的现象。自发现以来的两个多世纪里，人们常常推测胞质环流有助于细胞质中分子的运输和混合，进而影响细胞内稳态，但尚未有理论分析来量化这些过程。我们通过求解适用于诸如轮藻属和丽藻属等藻类典型“旋转式胞质环流”的流体流动与扩散的耦合动力学问题表明，胞质环流确实能够增强内部混合以及对外部条件变化的瞬态动力学响应，但其增强程度在很大程度上取决于螺旋流的螺距。轮藻指数生长期与这些过程增强程度最大的点相吻合，这说明了胞质环流可能具有发育方面的影响。
