Figure 5.

Cortical microtubule ordering and polarity in a recently divided BY-2 cell. A cultured BY-2 cell stably expressing HSP18.2 promoter-driven EB1b-GFP was observed after completion of cytokinesis to follow the pattern of cortical MT array organization and polarity. Images acquired at different times are accompanied by scatter plots of the direction in which the individual EB1b-GFP comets are headed. The angles of the comet trajectories were measured relative to the long axis of the cell (in degrees). The progressive acquisition of MT parallelism is closely associated with the establishment of net array polarity (∼90° in this cell). The Kolmogorov-Smirnov test showed that the distribution of MT angles is statistically indistinguishable from 10 min up to 45 min (p ∼ 0.5), but becomes statistically significant from 120 min onward (p ∼ 0.001) in this cell. Scale bar, 2 μm.