Section: New Results

Detection and estimation of membrane diffusion during exocytosis in TIRF microscopy

Participants : Antoine Basset, Charles Kervrann, Patrick Bouthemy.

Assessing the dynamics of plasma membrane diffusion processes in live cell fluorescence microscopy is of paramount interest to understand cell mechanisms. We investigated methods to detect vesicle fusion events, and estimate the associated diffusion coefficients in TIRFM image sequences [16] . In contrast to classical approaches, a diffusion coefficient is locally estimated for each detected fusing vesicle. We first detect the membrane fusion events and then select the diffusion configurations among them with a correlation test. To estimate the diffusion coefficient, a geometric model is fitted to the detected spot directly in the 2D+T subvolume. This recent estimation approach produced more satisfying results when compared to [16] . Diffusion events are reliably recognized, and the diffusion coefficient is accurately estimated for each diffusion event. This work will be integrated in a broader study, spanning from transport phase to membrane fusion, and non-diffusion events will be analyzed.

Reference:  [16]

Collaborators: Jean Salamero (UMR 144 CNRS-Institut Curie, STED team and PICT-IBiSA)

                          Jérôme Boulanger (UMR 144 CNRS-Institut Curie, STED team)

Figure 7. Left: Fusing vesicle (frame in red) in a TIRFM (UMR 144 CNRS-Institut Curie, PICT-IBiSA) sequence (frame 325, 50ms/frame). Right: Zoom-in view of the temporal evolution of the fusing vesicle.