Development of Simulator for Vesicular Transport in Cells - Application to Study of Mechanism of Vesicular Transportation and Cell Locomotion.

基于细胞分子生物学的最新知识，开发了一个细胞内囊泡运输模拟器。为了实现这一目标，采用了解析法和有限元法。(1)当将球形膜壳的开口周长与膜壳轴线平行展开时，存在几个点，其形状和张力变化较大，开口半径变化较小。这被认为是具有自发曲率的膜的屈曲现象。(2)在链状囊泡的重复单元中，发现圆柱管形和沙漏形在能量方面是稳定的。(3)理论上认为，链状囊泡和由链状囊泡衍生的圆柱形通道是能量稳定的形状，在血管内皮细胞中可能形成和呈现。(4)计算形状表明，面内剪切弹性和外周细胞质膜的影响是显著的，应在理论分析中加以考虑。(5)当开口半径较初始形状略有增大时，链泡的形状也发生了显著变化。在每次收缩消失的地方，经常观察到应变能的跳变现象。利用Mathematica开发囊泡输运模拟器的具体有限元方法(1)建立了基于弹性势能函数的有限元方法公式。通过施加附加表面压力，满足了膜表面积恒定的要求。(2)膜表面积恒定的要求对囊泡的变形形状有显著影响。(3)采用针对橡胶红细胞模型开发的Mooney-Rivlin型应变能密度函数。计算皮层张力为0.003-0.18 dyn/cm。该结果支持已知的0.03 dyn/cm的实验数据。少

A simulator for vesicular transport in cells was developed based on recent knowledge of molecular biology of the cell. Analytical method as well as finite element method were utilized to achieve the goal.1. Simulation of vesicular transport based on the analytical method(1) When the opening perimeter of a spherical membrane shell is unfolded with its perimeter kept parallel to its axis, there exists several points where the shapes and the tensions change significantly with slight changes of the opening radius. This is considered to be the bucking-like phenomena of the membrane with a spontaneous curvature.(2) In the repeating units of chained vesicles, it is found that the cylindrical tube shape and the hourglass shape are stable with respect to energy.(3) It is theoretically suggested that the chained vesicles and the cylindrical channel derived from the chained vesicles are some of the stable shapes with respect to energy and can potentially be formed and presented in the vascular en … More dothelial cell.(4) The computed shape suggests that the effects of in-plane shear elasticity and outer surrounding cytoplasmic membrane are significant and these should be taken into account in theoretical analysis.(5) The chained vesicle changes its shape dramatically even when the opening radius slightly increases from the starting shape. The jump-like phenomena of strain energy was often observed where each constriction disappears.2. Development of the specific finite element method for vesicular transport simulator by utilizing Mathematica(1) Formulation of the finite element method was developed based on elastic potential energy function. The requirement of constant surface area of the membrane was satisfied by implementing additional surface pressure.(2) The requirement of constant surface area of the membrane has significant effect on deformed shape of the vesicle.(3) Mooney-Rivlin type strain energy density function, which was developed for rubber red cell model, was utilized. The computed cortical tension was given as 0.003-0.18 dyn/cm. This results support the know experimental data of 0.03 dyn/cm. Less