INTERACTIVE COMPUTER-ASSISTED POSITION ACQUISITION PROCEDURE DESIGNEDFOR THE ANALYSIS OF ORGANELLE MOVEMENT IN POLLEN TUBES

An interactive computer-assisted video microscopy method has been deve loped for the acquisition of extensive data on the sequential position s of pollen tube organelles, which cannot be automatically tracked usi ng geometric or motion patterns. The method consists of video microsco py, analog and digital contrast enhancement, digital time-lapsing of t he images, and interactive selection of positions in a coordinate syst em corresponding to the cell shape and real size. Data on 15,000 posit ions acquired with this method have been used to make quantitative ana lyses of the movement patterns of the organelles. From these analyses and the reconstruction of 900 trajectories, it appears that movements are random in the tip of the pollen tube but become more directed in d istal regions of the cell, indicating an increase in axial arrangement of the actin filaments. (All custom-made software is available from t he authors on request.) Cytometry 32:263-267, 1998. (C) 1998 Wiley-Lis s, Inc.