Fig. 7. upd expression is induced by eyg and mediates eyg function. (A) The hypomorphic upd allele os¹ has small eyes. Similarly, the hypomorphic eyg¹ mutants also have small eyes. (B) The os¹; eyg¹ double mutants have total absence of eyes. (C) The os¹ eye phenotype was enhanced by removing one copy of eyg in eyg^M3-12/+ heterozygote. (D) upd-lacZ (anti-ß-galactosidase, red) expression is not detected in eyg¹ mutant eye disc. Arrow indicates its normal expression site. (E,F) Clonal expression of eyg (marked by GFP, green) at the eye disc margin non-autonomously induced upd-lacZ (red) expression (arrowhead in F, magnified view of fromed area in E. (G) dpp>upd fully rescued the eye development which is absent in eyg¹/eyg^M3-12. The eyes are slightly larger than wild-type (compare with Fig. 2A). (H) In os¹ mutant, the overexpression of eyg (ey>eyg) did not cause eye enlargement, which ey>eyg did in wild-type background (I).