Analyzing Real‐Time Video Microscopy: The Dynamics and Geometry of Vesicles and Tubules in Endocytosis
With the advent of live cell imaging microscopy, new types of mathematical analyses and measurements are possible. Many of the real-time movies of cellular processes are visually very compelling, but elementary analysis of changes over time of quantities such as surface area and volume often show that there is more to the data than meets the eye. This unit outlines a geometric modeling methodology and applies it to tubulation of vesicles during endocytosis. Using these principles, it has been possible to build better qualitative and quantitative understandings of the systems observed, as well as to make predictions about quantities such as ligand or solute concentration, vesicle pH, and membrane trafficked. The purpose is to outline a methodology for analyzing real-time movies that has led to a greater appreciation of the changes that are occurring during the time frame of the real-time video microscopy and how additional quantitative measurements allow for further hypotheses to be generated and tested.
Keywords: endocytosis; video microscopy; endosomal trafficking; membrane trafficking
Table of Contents
- Unit Introduction
- Data and Measurement
- Conservation of Surface Area
- Measurement of Volume
- Flux Across a Membrane, Solute Concentration, and pH Change
- Pressure, Tension, and Morphology
- Vesicle Fusion
- Proportionality and Surface Area
- Literature Cited
Figure 4.16.2 The rate of decrease of surface area of the vesicle in The Movie (frames 22 to 83), with an exponential best fit curve (dotted). Surface area is given as four times the area of an ellipse fitted to the vesicle membrane surface.
Figure 4.16.6 Vesicle membrane subdomains or patches. The vesicle membrane contains subdomains (shown in grey) on which tubulation is initiated. As the tubule grows the subdomain membrane is drawn into the tubule and the subdomain decreases in size.
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