Flatness and intrinsic curvature of linked-ring membranes

摘要

Recent experiments have elucidated the physical properties of kinetoplasts,which are chain-mail-like structures found in the mitochondria of trypanosome parasites formed from catenated DNA rings.Inspired by these studies,we use Monte Carlo simulations to examine the behavior of two-dimensional networks(“membranes'')of linked rings.For simplicity,we consider only identical rings that are circular and rigid and that form networks with a regular linking structure.We find that the scaling of the eigenvalues of the shape tensor with membrane size are consistent with the behavior of the flat phase observed in self-avoiding covalent membranes.Increasing ring thickness tends to swell the membrane.Remarkably,unlike covalent membranes,the linked-ring membranes tend to form concave structures with an intrinsic curvature of entropic origin associated with local excluded-volume interactions.The degree of concavity increases with increasing ring thickness and is also affected by the type of linking network.The relevance of the properties of linked-ring model membranes to those observed in kinetoplasts is discussed.