Figure 3. Automated analysis of peroxisome movement along axon-like processes.
(A–E) Images from a time-lapse movie of a control axon-like process at the times indicated. GFP-labelled peroxisomes are evident (green dots). Three example peroxisomes (P1-P3, circled) indicate peroxisomes moving different distances during the four minutes. (F) The computer-generated representation of the peroxisomes in the image shown in A (red dots). (G) The computer-generated tracks of movement of P1-P3 assessed from successive 2 second images over the 4 minute observation period. Scale bar in (G) applies to (A–G) 10 μm. (H–J) The speed of peroxisome movement was plotted against time for the three identified peroxisomes. At this time scale, peroxisome movement was characterised by saltatory movement with bursts of movement separated by rest periods. The fastest moving peroxisomes were characterised by multiple fast saltatory movements with rest periods, as for peroxisome P1. The majority of peroxisomes moved either like peroxisome P2, with multiple slow saltatory movements characterised as Brownian-like motion, or were immobile like peroxisome P3.