Section: New Results

Correlation-based method for membrane diffusion estimation during exocytosis in TIRFM

Participants : Ancageorgiana Caranfil, Charles Kervrann.

The dynamics of the plasma membrane of the cell is not fully understood yet; one of the crucial aspects to clarify is the diffusion process during exocytosis. Several image acquisition modalities exist, including TIRFM (Total Internal Reflection Fluorescence Microscopy), that have successfully been used to determine the successive steps of exocytosis. However, computing characteristic values for plasma membrane dynamics is problematic, as the experimental conditions have a strong influence on the obtained data, and a general model of molecular interaction dynamics cannot be determined.

In the PhD thesis of A. Caranfil, we have developed a computational approach to adapt the popular temporal image correlation spectroscopy (TICS) method to the analysis of a single fusing vesicle. The biophysical diffusion model parameters (for TfR protein) are estimated by an Approximate Bayesian Computing procedure which supplies the conditional expectation and maximum a posteriori estimators from temporal correlation data. Unlike TICS, our approach is robust to noise, estimation window size, spot location and non-uniform background. It can serve in biological studies investigating diffusion processes involved in exocytosis mechanisms.

Collaborators: Francois Waharte (UMR 144 CNRS-Institut Curie, PICT-IBiSA).