Tre1 regulates germ cell polarization and G protein localization. (A and B) Electron micrograph images of wild-type and tre1 germ cells at stage 9. Germ cells were identified by the presence of a large nucleus and the lack of white lipid droplets. (A) In wild-type embryos at stage 9, germ cells are organized into a group with little interaction with the surrounding midgut. Germ cells display polarized morphology, with their nuclei facing the midgut and their tails toward the center of the cluster. (B) In tre1 mutants at stage 9, germ cells are not well organized into a radial cluster and are not polarized like the wild type. (C–J) Gβ13f protein localization in the wild type and tre1 mutants. At stage 5, Gβ13f protein (red) is uniformly distributed along the cell surface in wild-type (C and D) and tre1 mutant (G and H) germ cells (green). At stage 9, Gβ13f protein is localized to the tail region of wild-type germ cells (E and F) but is uniformly distributed in tre1 mutant (I and J) germ cells (Gβ13 channel shown in D, H, F, and J). (K–R) Rho1 protein localization in the wild type and tre1 mutants. At stage 5, Rho1 protein (red) is uniformly distributed along the cell surface in wild-type (K and L) and tre1 mutant (O and P) germ cells (green). At stage 9, Rho1 protein is localized to the tail region of wild-type germ cells (M and N) but is uniformly distributed in tre1 mutant (Q and R) germ cells (Rho1 channel shown in L, P, N, and R). Germ cells are visualized by anti-Vasa antibody (green). Bars, 20 μm.