Fig. 5. Misexpression of islet1 RNA induces PMN formation and inhibits interneuron formation. (A,B) 28 hpf embryos labeled with zn1 and znp1 (green) and Islet (red) Abs. Control embryos (A) have MiP axons (arrows), CaP axons (arrowheads) and several PMN cell bodies (inset; zn1 Ab; dots). Misexpression of islet1 RNA (B) causes a thicker ventral motor nerve (arrowheads) and more zn1-positive cell bodies (inset, dots). (C,D) 20 hpf embryos labeled with islet2 riboprobe. islet2 is expressed in one or two PMNs per segment (black dots) in control embryos (C); the second cell is VaP, a duplicate CaP that is sometimes present and typically dies (Eisen et al., 1990). islet2 is expressed in two to four PMNs per segment in embryos misexpressing islet1 RNA (D). (E,F) 28 hpf embryos labeled with GABA Ab. The number of cells in the V-K position (asterisks) is decreased in embryos misexpressing islet1 RNA (F) when compared with controls (E). Scale bar: 20 µm.