Ectopic expression of bnl in hairy mutant embryos.

In h⁶⁷⁴ heterozygous embryos (A), bnl RNA is expressed in clusters close to the tracheal visceral branch (vis) (A, large arrows), in dorsal clusters (dor) (A, small arrowheads) and in lateral clusters (lat) (A, large arrowhead). In h⁶⁷⁴ homozygous embryos (B), the dorsal clusters of bnl RNA are expanded (B, small arrowheads). In h⁴⁷ homozygous embryos (C and D), clusters of bnl RNA close to the tracheal visceral branch (vis) (C, large arrow) and dorsal clusters (dor) (D, small arrowheads) are expanded. In wild-type embryos (E and E'), a cluster of bnl expression is found close to the tracheal ganglionic branch (gan) (E and E', small arrows). In h^ACT embryos (F and G), bnl RNA close to the tracheal visceral branch (vis) (F, large arrows) and close to the ganglionic branch (gan) (G, small arrows) are expanded. All embryos shown are at stage 13 and were processed for ISH for bnl RNA and lac-Z to distinguish h⁶⁷⁴ heterozygous from homozygous embryos. Embryos in panels A and B are lateral views whereas embryos in panels C–G are ventral-lateral views. Panel E' is a more internal focal plane than that shown in panel E.