Fig. 8. spen is not required for Wg signaling in the embryo. (A,D) Micrographs of cuticles of wild type (A) and embryos containing transgenes P[da-Gal4] and P[UAS-spen^DN]^III (D) reared at 25°C. Expression from P[UAS-spen^DN] has variable effects on cuticle patterning, ranging from wild type (P[UAS-spen^DN]^II at 25°C, data not shown), moderate reduction of denticles (D) to complete disruption of cuticle formation (P[da-Gal4], P[UAS-spen^DN]^III containing embryos reared at 29°C, data not shown). (B,C,E,F) Confocal images of stage 11 embryos containing P[prd-Gal4] and either P[UAS-TCF^DN] (25°C; B,C) or P[UAS-spen^DN]^III (29°C; E,F). Samples were stained for En (B,E) or Slp1 (C,F). En and Slp1 stripes remain wild type in spen^DN-expressing embryos. (G-I) Confocal images of stage 13 wild-type embryos (G) and embryos containing transgenes P[twi-Gal4] and P[UAS-spen^DN]^II (H,I) reared at 25°C. Expression from P[UAS-spen^DN] has variable effects on the Eve pericardial expression, ranging from wild type (H) to an increase in Eve-positive cells (I). Some embryos containing transgenes P[twi-Gal4], P[24B-Gal4] and P[UAS-spen^DN]^II reared at 25°C or 29°C also display disorganization of Eve-expressing cells or occasional gaps missing Eve expression, in addition to an overall increase in Eve-positive cells (data not shown). These effects are qualitatively different from a blockage of Wg signaling [ectopic denticles, loss of En (B) and Slp-1 (C) stripes and loss of Eve in pericardial cells].

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