Fig. 7. FRAP of GFP-actin. Maximum projections of confocal stacks of scutellar bristles from a hs-GAL4/+; UAS-GFP-actin pupa are shown. Panel A shows the bristles immediately after bleaching. The other micrographs are equivalent images taken with a 1 hour interval. Panels A, C and E contain an insert showing a higher magnification view of the bleached/non-bleached boundary. Note that the distinction between the bleached and unbleached region remains obvious for the entire 5 hour experiment. The retrograde movement of the actin is also obvious. Panel G is a plot of the distance from the distal edge of the proximal unbleached region to the boundary of the socket cell (see arrow). This approach was taken as the actin bundles extend down into the cell and their proximal end was sometimes out of the range of z sections we obtained. The measurements in G are for the bristle on the right. This distance decreased over time and provides a measure of the retrograde movement of actin filaments. Note that the bleached/unbleached border becomes uneven over time due to the differential retrograde movement of individual actin bundles. Panel H is a plot of the fluorescence intensity at locations approximately 5 µm either distal or proximal to the bleached/unbleached border. Note that the proximal region of these bristles was substantially brighter than the distal region, which may be a consequence of the heat shock hours prior to the start of the experiment. There is a slight decrease in the intensity of the bright proximal unbleached region and a slight increase in the intensity of the bleached regions over time.