CLASSIFICATION OF ORGANELLE TRAJECTORIES USING REGION-BASED CURVE ANALYSIS

A method based on analysis of the region of movement and the functioni ng of a-he acto-myosin cytoskeleton has been elaborated to quantify an d classify patterns of organelle movement in tobacco pollen tubes. The trajectory was dilated to the region of movement, which was then redu ced to give a one-pixel-wide skeleton, represented by a graph structur e. The longest line in this skeleton mas hypothesized to represent the basic track of the organelle along a single actin filament, Quantitat ive features were derived from the graph structure, direction of movem ent on the longest skeletal line, and distance between skeletal Line a nd particle. These features corresponded to biological events like the amount of linear movement or the probability of attachment of an orga nelle to the actin filament. From 81 analyzed organelle trajectories, 17 had completely linear, 17 had completely non-linear, and 47 had alt ernating linear and non-linear movement. Selected features mere employ ed for classification and ranking of the movement patterns of a repres entative sample of the population of organelles moving in the cell tip . The presented methods can be applied to any field where analysis and classification of particle motion are intended. (C) 1997 Wiley-Liss, Inc.