  In this work we demonstrate how the first order phase transition in giant
unilamellar vesicles (GUVs) can function as a trigger for membrane fission.
When driven through their gel-fluid phase transition GUVs exhibit budding or
pearl formation. These buds remain connected to the mother vesicle presumably
by a small neck. Cooling these vesicles from the fluid phase (T>Tm) through the
phase transition into the gel state (T<Tm), leads to complete rupture and
fission of the neck, while the mother vesicle remains intact. Pearling tubes
which formed upon heating break-up and decay into multiple individual vesicles
which then diffuse freely. Finally we demonstrate that mimicking the
intracellular bulk viscosity by increasing the bulk viscosity to 40cP does not
affect the overall fission process, but leads to a significant decrease in size
of the released vesicles.
