Figure 4. dGMF promotes the migration of border cells and increases the dynamics of cellular extensions.

(A) Time lapse image of the egg chamber where border cells have reached 50% of their migration path. Border cells are marked by expression of actin-GFP, the tissue surrounding them with red membrane dye FM4-64. For analysis, the movies were divided to early and late phases according to the time point where border cells first reach 50% of their migration path. Bar, 20 µm. (B) Quantification of net speed (yellow bars) and speed of tracked single cells (blue bars) from live movies. Net speed was calculated based on distance between the start position and end position of the border cluster center (yellow lines). Single cell speed was calculated based on the path that nucleus of a single border cell travelled (white line in panel A, blue line in panel B). N= 17–38. Data are represented as mean ± SEM. *** p < 0.001, ** P < 0.01, Students T-test. (C) Still images from time lapse movies representing typical morphology of border cell clusters during early and late phases of posterior migration. Bar, 10 µm. (D) Left hand side: Extensions (bottom image, black objects are extensions detected from the macro) of the border cell clusters were extracted from projected 2D GFP-channels (upper image) by using automated macros. Right hand side: the persistence of extensions in minutes was quantitated by using the customized macros. Data are represented as mean ± SEM.** P < 0.01, Students T-test. (E) Average areas of the front, side and back extensions. For measuring the area of extensions, each time frame was analysed and extensions were separated according to their direction into forward (0–45° and 315–360°), backward (135–225°) and sideway (the rest) directions. Data are represented as mean ± SEM. Genotypes in Figure 4 are: 2xsblo-Actin-GFP/+ (control), 2xsblo-Actin-GFP. gmf¹/gmf¹ (dGMF −/−). See also Figure S4 and movies S2 and S3.