Fig. 7. Sra-1 affects F-actin formation. During pupal development, bristle morphology is prefigured by an apical F-actin extension, which can be visualized by phalloidin staining. All pupae were dissected 36 hours after puparium formation. (A) Wild type. (B) After expression of sra-1, dsRNA expression (one copy) using sca-GAL4 bent F-actin bundles, which are never seen in wild type, can be detected. (C) After expression of one copy of the sra-1CMyr construct, no F-actin forms at the site where bristles are expected to develop (star). (D) Following expression of full-length membrane tethered Sra-1 protein using the sca-GAL4 driver, F-actin formation is initiated in a broader region of the apical cell surface (arrow). In addition, the F-actin at the cell boundary appears to have a `fuzzier' organization (arrowheads).