Figure 1.

Polymer mass decay in Listeria actin comet tails is best fit by a simple exponential. (A) Maximum intensity projection of GFP-actin in a Listeria comet tail in a BSC-1 cell, taken over a timelapse movie. Red contour shows a trace of the Listeria trajectory. Scale bar = 5 μm. (B) GFP-actin decay curve (blue circles) for the Listeria trajectory in panel A. Error bars give the standard deviation in the decay curve across the trajectory. Smooth curves give best fits of the polymer mass decay to a simple exponential exp(–τ) (red, χ²_exp = 0.0087); inflected exponential (1 + τ) · exp(– τ), (green, χ²_inf = 0.24); hyperbola 1/(1 + τ), (black, χ²_hyp = 0.40); and squared hyperbola 1/(1 + τ)², (purple, χ²_sqh = 0.11). All fits contain a single fitting parameter k, where τ = kt. (C) Ratio of sum-squared errors comparing best fits of other candidate curves to that of a simple exponential: (I) F = χ²_inf/χ²_exp, 〈F〉 = 5.9; (II) F = χ²_hyp/χ²_exp, 〈F〉 = 22.7); and (III) F = χ²_sqh//χ²_exp, 〈F〉 = 8.2. Fits from 23 Listeria comet tails were used. The simple exponential is the best fit to experimental data.