Enhanced Dynamics of Confined Cytoskeletal Filaments Driven by Asymmetric Motors.

Cytoskeletal filaments and molecular motors facilitate the micron-scale force generation necessary for the distribution of organelles and the restructuring of the cytoskeleton within eukaryotic cells. Although the mesoscopic structure and the dynamics of such filaments have been studied in vitro and in vivo, their connection with filament polarity-dependent motor-mediated force generation is not well understood. Using 2D Brownian dynamics simulations, we study a dense, confined mixture of rigid microtubules (MTs) and active springs that have arms that cross-link neighboring MT pairs and move unidirectionally on the attached MT.

Phase transitions and gelation of silica-polystyrene mixtures in benzene.

We have performed experiments on mixtures of sterically stabilised silica particles and large poly(styrene) polymers in benzene. Using this model system, we were able to independently vary short and long ranged attractive interactions by changing the temperature and/or the polymer concentration. We show that the addition of long ranged attractions to particles with initially only short ranged attractions leads to the appearance of a gas-liquid phase transition.