In ftz-f1ex7/ftz-f103649 mutants, no pupation occurs; when ftz-f1hs.PM is induced at 8hr APF or later, pupation occurs and is delayed (length of delay depends on the timing of the heat shock).
Nervous system MARCM somatic cell clones of ftz-f1ex7 mutants, under the control of Scer\GAL4Tab2-201Y retain their larval-type branching of axons into the adult stage. The mutant phenotype can also be seen in single- and two-cell clones. Approximately 80% of ftz-f1ex7 mutant cell clones appear wild-type, with 20% appearing unpruned. ftz-f1ex7 neuroblast clones are indistinguishable from wild-type at the third instar larval stage but display no signs of pruning at 24 hours after puparium formation, in contrast to their wild-type counterparts in which most axons are fully pruned.
ftz-f1ex7 heterozygotes display normal γ neuron pruning.
ftz-f1ex7 homozygotes which have been rescued by expression of ftz-f1hs.PM using heat shock 13-16 hours after egg laying (AEL) survive for a few days, but do not progress to second instar larvae even 24 hours after hatching. If the larvae are heat shocked again at 33oC for 60 minutes during the later period of the first instar stage (within 42-47 hours AEL) about 30% succeed in ecdysis and progress to the second instar stage. Again, they survive for a few days, but cannot progress to third instar larvae. The larvae have two pairs of mouth hooks, cephalopharyngeal skeletons, anterior and posterior spiracles and double tubular tracheae, and cuticle for the third instar is present in addition to that for the second instar. This indicates that the larvae have prepared the structures appropriate to third instar larvae, but failed in the second ecdysis. The rescued second instar larvae progress to third instar larvae upon heat shock at 33oC for 60 minutes during the late period of the second instar stage (within 66-71 hours AEL), although efficiency of rescue is very low (only 2.5% progress to prepupae). Most ftz-f1ex7/ftz-f103649 transheterozygotes die before reaching the prepupal stage, but 3% do progress to prepupae. The development of this 3% arrests before prepupal stage P4. Most ftz-f1ex7/ftz-f103649 transheterozygotes die before reaching the prepupal stage, but 3% do progress to prepupae. The development of this 3% arrests before prepupal stage P4. Larval salivary glands are still present even 24 hours after puparium formation (in contrast to wild type). The optic lobes do not expand as in wild type and the subesophageal neuromeres and thoracic neuromeres do not separate. Arrested development is also manifested as leg elongation, edge constriction of the wing disc and morphological changes in the midgut and Malpighian tubules.