Doctoral thesis viva voce : Serge Dmitrieff

Biological membranes : transport and identity

In this theoretical work, we studied the relation between membrane identity, transport and organelle structure in cells.

We first study the entry of pathogens such as viruses or toxins in cells. We showed how the chemical and physical properties of the cell membrane can control the entry of molecules or bodies.

We then focus on transport in the Golgi apparatus. We see that by an adequate formulation of transport in the Golgi, we can give an accurate interpretation of existing experimental data. We show that differences of identity allow the localization of molecules in one cisterna of the Golgi stack.

Then, we show that we can write general requirements on the transport processes to enable the heterogeneity of compartments. We show that this requirements may have dramatic functional consequences on transport.

Eventually, we study the building of new compartments in the cell. We consider one membrane compartment, which we can see as the precursor of the Golgi apparatus, in which the membrane lipids undergo a chemical reaction and are transformed into another lipid species (as occurs in the Golgi apparatus). There can be a competition between the kinetics of phase separation and the kinetics of the chemical reaction which control the structure of the compartment.