Fig. 7. Fusions of Grk to the cytoplasmic tails of Yl, dEmp24 or Cni. (A) Wild-type egg. The anterior pole bears a micropyle, and the dorsal side carries two respiratory appendages. (B) Egg from a cni^AA12/cni^AR55 female. The egg is ventralized (reduction of dorsal appendages), but the anterior and posterior structures differentiate correctly. (C) Egg from a cni^AR55/cni^AR55 female. The egg is completely ventralized and both ends differentiate into anterior structures (micropyle), indicating complete loss of Grk function. (D) Egg from a grk^HF48/grk^2B6 female carrying a transgene replacing the Grk transmembrane and cytoplasmic domains with the corresponding domains of Yl (grk-Yl TMC). The transgene is able to rescue the grk oogenesis phenotype. (E) The grk-Yl TMC transgene shows no function in an amorphic cni background. (F) Egg from a cni^AR55/cni^AR55 female expressing the Grk extracellular and transmembrane domains fused to the dEmp24 cytoplasmic domain (grk-Emp24 Cyt). The egg is partially ventralized, but the anteroposterior axis is correctly specified. (G) Egg from a cni^AR55/cni^AR55 female expressing the Grk extracellular and transmembrane domains fused to the presumptive cytoplasmic domain of Cni (grk-Cni Cyt). The anteroposterior axis is correctly polarized and the dorsal appendages are partially rescued.