Dynamics of lipid membrane tubes

Membrane tubes are structures ubiquitous in cells, and understanding their dynamics and morphology is of vital importance for cellular biophysics. This thesis will discuss several aspects of the dynamics of membrane tubes in situations where they are driven out of equilibrium by various biologically inspired processes. We analyse the inflation of membrane tubes and their subsequent instability due to ion pumps driving an osmotic pressure difference. This is inspired by the structure of an organelle called the contractile vacuole complex, and leads to a new instability with a much longer natural wavelength than a typical pearling instability. The stability of membrane tubes with a shear in the membrane ow is analysed and a novel helical instability which acts to amplify the fluctuations is found. We discuss the relevance of this instability in the process of dynamin-mediated tube scission. Finally we consider the dynamics and fluctuations of a membrane tube with active forces acting on it