Articles by Tanumoy Saha in JoVE
A Graphical User Interface for Software-assisted Tracking of Protein Concentration in Dynamic Cellular Protrusions Tanumoy Saha1, Isabel Rathmann1, Milos Galic1 1DFG Cluster of Excellence 'Cells in Motion', (EXC 1003), Institute of Medical Physics and Biophysics, University of Muenster We present a software solution for semi-automated tracking of relative protein concentration along the length of dynamic cellular protrusions.
Other articles by Tanumoy Saha on PubMed
Automated Analysis of Filopodial Length and Spatially Resolved Protein Concentration Via Adaptive Shape Tracking Molecular Biology of the Cell. Nov, 2016 | Pubmed ID: 27535428 Filopodia are dynamic, actin-rich structures that transiently form on a variety of cell types. To understand the underlying control mechanisms requires precise monitoring of localization and concentration of individual regulatory and structural proteins as filopodia elongate and subsequently retract. Although several methods exist that analyze changes in filopodial shape, a software solution to reliably correlate growth dynamics with spatially resolved protein concentration along the filopodium independent of bending, lateral shift, or tilting is missing. Here we introduce a novel approach based on the convex-hull algorithm for parallel analysis of growth dynamics and relative spatiotemporal protein concentration along flexible filopodial protrusions. Detailed in silico tests using various geometries confirm that our technique accurately tracks growth dynamics and relative protein concentration along the filopodial length for a broad range of signal distributions. To validate our technique in living cells, we measure filopodial dynamics and quantify spatiotemporal localization of filopodia-associated proteins during the filopodial extension-retraction cycle in a variety of cell types in vitro and in vivo. Together these results show that the technique is suitable for simultaneous analysis of growth dynamics and spatiotemporal protein enrichment along filopodia. To allow readily application by other laboratories, we share source code and instructions for software handling.
Simultaneous Measurement of Mass and Rotation of Trapped Absorbing Particles in Air Optics Letters. Sep, 2016 | Pubmed ID: 27628396 We trap absorbing micro-particles in air by photophoretic forces generated using a single loosely focused Gaussian trapping beam. We measure a component of the radial Brownian motion of a trapped particle cluster and determine the power spectral density, mean squared displacement, and normalized position and velocity autocorrelation functions to characterize the photophoretic body force in a quantitative fashion for the first time. The trapped particles also undergo spontaneous rotation due to the action of this force. This is evident from the spectral density that displays clear peaks at the rotation and the particles' inertial resonance frequencies. We fit the spectral density to the well-known analytical function derived from the Langevin equation, measure the resonance and rotation frequencies, and determine the values for particle mass that we verify at different trapping laser powers with reasonable accuracy.