Fig. 1

Inhibition of PKA phenocopies misexpression of hh. (A) Dorsal view (optical section) of a 28-hpf wild-type embryo. The lens (l) and pigmented retinal epithelium (pre) are evident. (B) Dorsal view (optical section) of a 28-hpf wild-type embryo injected with dnPKA RNA. Pigmented retinal epithelia have not developed; one lens is slightly reduced in size while the other has not developed. The lens was missing or reduced in size in 74% (n - 126) of eyes developing in dnPKA-injected embryos. Also, the ventricles of the brain fail to form properly in both dnPKA- and hh RNA-injected embryos. (C) pax2 RNA in a 14-hpf wild-type embryo (dorsal view). pax2 labels the anterior/proximal part of the optic vesicle (ov). (D) pax2 RNA in a 14-hpf embryo injected with dnPKA RNA (dorsal view). pax2 is expressed ectopically in the distal/posterior portion of the eye vesicle. In embryos injected with dnPKA RNA at the 1- to 8-cell stage, 89% (n - 46) displayed ectopic pax2 in the eye. (E) F-spondin RNA in a 28-hpf wild-type embryo (lateral view). Labeling is in the floor plate (fp). (F) F-spondin RNA in a 28-hpf embryo injected with dnPKA RNA (lateral view). Ectopic F-spondin was observed in 81% (n - 69) of dnPKA-injected embryos. (G) pax2 protein in the optic vesicle of a 15-hpf embryo which was injected with RNA encoding a dnPKA–GFP fusion protein. Anterior is to the upper left. The white dots roughly outline the extent of the optic vesicle. Labeling in the anterior/proximal half of the optic vesicle represents wild-type expression (compare to C) whereas labeling in the posterior/distal regions is ectopic. The white arrows indicate cells in which dnPKA–GFP was not detected (see H) but which express pax2 in ectopic regions of the eye vesicle. (H) dnPKA–GFP fusion protein in the same confocal section shown in G. dnPKA–GFP is primarily cytoplasmic. The white arrows indicate cells in which dnPKA–GFP was not detected but which express pax2 in ectopic regions of the eye vesicle (G). dnPKA–GFP was also not detected in these cells in adjacent z-series images taken 3 mm apart. (I) Superposition of G and H showing pax2 protein (red) and dnPKA-GFP (green). Key: fp, floor plate; l, lens; ov, optic vesicle; pre, pigmented retina epithelium; r, retina.