Fig. 7. Effects of ectopic ttx-3 expression and dependence on ceh-10 activity. (A,B) RID and CAN can adopt AIY-like features upon ectopic expression of ttx-3. (A) A transgenic animal is shown that expresses ttx-3prom::gfp (normally only expressed in AIY; see Fig. 3B) and unc-119::ttx-3 from the independently integrated arrays mgIs18 and otIs97IV, respectively, in a ttx-3(ks5) background. Note that the autoregulatory defect of ttx-3prom::gfp in AIY is completely rescued and that ectopic expression is induced in RID and CAN. The animal is slightly twisted owing to the presence of a rol-6 injection marker. Ectopic RID and CAN expression could be observed with several independent transgenic lines (see Materials and Methods). (B) Ectopic expression of ceh-23::gfp in RID upon pan-neuronal ttx-3 expression. The genotype of this strain is kyIs5IV; otEx65. Eleven out of 14 examined adults show expression in RID. kyIs5 animals never show GFP expression in RID (n>20). (C) ceh-10 dependence of ectopic ttx-3prom::gfp expression. Homozygous ceh-10(gm58) offspring of ceh-10(gm58)/+; otIs97mgIs18IV hermaphrodites arrest as L1 larvae and were identified based on their clr phenotype. In these animals, no GFP signal can be detected in RID, CAN, or AIY (the approximate position of the AIY interneurons is indicated with an arrow), showing that expression of ttx-3 from an exogenous promoter can not rescue the ceh-10(gm58) phenotype. White dots derive from autofluorescent gut granules. (D) Summary of expression of several AIY cell fate markers in RID and CAN either in wild-type animals or in animals that pan-neuronally express ttx-3. Ectopic sra-11::gfp expression in RID was observed in 19/19 animals (data not shown) and was never observed in wild-type animals (n>20).
