Fig. 4. Fab-8 is not able to substitute for Fab-7. (A-C) Cuticles were prepared from adult males (note that A7 does not contribute to any visible cuticle structures in the adult male). (A) Wild-type: the A6 sternite is recognizable by the absence of bristles (black arrow). (B) In Fab-7² homozygote males, A6 is partially transformed into A7 as revealed by the reduction of the A6 tergite (Mihaly et al., 1997). (C) In F7F8 males, the transformation of A6 to A5 is visible on the sixth sternite, which exhibits an A5 shape and has bristles (black arrow). (D) Diagram of the F7F8 substitution. (E-G) Abd-B expression in the embryonic CNS. (E) Wild-type. (F) Fab-7²: the Abd-B expression level in PS11 increases to the level normally observed in PS12. (G) F7F8: the Abd-B expression level in PS11 decreases to a level similar to that seen in PS10.