SIMULATION OF THE EFFECTS OF MICROTUBULES IN THE CORTICAL ROTATION OF AMPHIBIAN EMBRYOS IN NORMAL AND ZERO GRAVITY

摘要

Microtubules in the first cell cycle of an amphibian embryo are modeled as initially randomly oriented semi-flexible rods, composed of several point-masses interacting with one another like masses on springs with longitudinal and transverse stiffness. They are also considered to be space-filling rods floating in a viscous fluid (cytoplasm) experiencing drag forces and buoyancy from the fluid under a variable gravity field. Their randomly distributed pushes on the surrounding spherical container (the cortex of the one-cell stage amphibian embryo) have a statistical nonzero average that creates a torque causing a rotational relative displacement between the cytoplasm and the rigid cortex. The simulation has been done in zero and normal gravity and it confirms the observation that the cortical rotation occurs in zero gravity as well as on Earth.