Bienvenue sur la page publique de Serge Dmitrieff

Post-Doctorate research

• Analytical modeling of the mitotic spindle

• Modelization of endocytic events in Yeast

PhD

• Cooperative transport of proteins in cellular organelles

  
  Considering one or various species of proteins being exchanged between organelles through vesicular transport, we find under which condition cooperativity (i.e. specific fusion of vesicles according to their concentrations) enable the emergence of distinct organelle identity. We study the consequences of cooperative transport on the efficiency of an organelle such as the Golgi apparatus, responsible for protein maturation and sorting, and show that it yields a low-throughput, high-efficiency filter at high protein concentration.
  Serge Dmitrieff and Pierre Sens, Phys. Rev. E 83, 041923 (2011) -- Download main text.
  Serge Dmitrieff and Pierre Sens, Intl. J. Biochem. & Cell Biol., 2012

• Entry of pathogens in the cell

  We show how a virus (sv40), its capsid sub-units, and toxins (Shiga and Cholera) may enter the cell in a clathrin-free pathway. Proteins outside the cell bind to lipid receptors on the membrane and induce large deformation of the membrane. While membrane invagination by both viruses and isolated proteins is driven by line tension, viruses are shown to be much less sensitive to membrane tension and do no require spontaneous curvature. Our analytical predictions show a good qualitative agreement with experimental results.
  H Ewers et al., Nature Cell Biology 12, 2010 -- Download main text, Sup. mat.

• Phenomenological model of intra-cellular transport

  We show how the two competing hypothesis of transport in the Golgi apparatus, cisternal maturation and vesicular transport, can be modeled in the same formalism. We show that vesicular transport yields a predictable effective diffusion coefficient. We discuss whether the existing experiments may or may not help us distinguish between the current hypothesis.
  Serge Dmitrieff, Madan Rao and Pierre Sens, in preparation.

• Generation 'from scratch' of non-identical compartments in the cell

  Using a formalism borrowed from phase transitions, we study the generation of strong local heterogeneities of concentration in a membrane where one species of lipid is chemically transformed into another. There is a competition between the maturation of a lipid species and the dynamics of domain growth, and we may find under which conditions those domains may bud from the membrane to form new, differentiated organelles.
  Serge Dmitrieff and Pierre Sens, in preparation.