In response to pheromone treatment, low-intensity MFA2 mRNA-containing granules are distributed all over the cell, whereas a high-intensity granule localizes to the shmoo before and during its growth. Cells coexpressing MFA2-U1A and U1A-GFP (yAS20) were treated with 3 nM αF for 1 h. The distribution of MFA2 mRNA-containing granules (green) was analyzed by time-lapse confocal microscopy, 30 min after addition of αF using a laser-scanning confocal microscope (LSM 510; Carl Zeiss). Images were captured every 3 min during 1 h, for a total of 20 frames. The video shows a fast-forward version, in which the 60 min are shown in 4 s (speed rate 5 frames/s). Note that during αF treatment, the high-intensity and immotile granules were localized in the shmoo as early as 30 min after αF addition and remained associated with the shmoo tip during its growth. These granules remained immotile during the entire course of the experiment. In parallel experiments, we noticed that their size first increased during the first 2 h after αF addition, and later it decreased. In contrast, the low-intensity granules were distributed all over the cell and were motile throughout imaging. Fig. 2 C shows representative snapshots that were chosen from the Video 1.
