Expression of ftzhs.PS using heat shock results in pair-rule defects in 36% of embryos; odd-numbered parasegments are eliminated.
Expression of ftzhs.PS using heat shock from 2.25-2.75 hours after egg laying results in a pair rule phenotype. The segments that remain are about 1.4 times wider than wild-type segments and the cuticle is about 70% the length of a wild-type cuticle. The number of embryos that hatch and the number of adults eclosing is dramatically reduced compared to controls. Parasegments 3 to 6 are unevenly spaced at stage 6-7 with parasegments 4 and 6 being about 1.4 times wider than wild-type and parasegments 3 and 5 being about 0.6 times the wild-type width. The wider parasegments contain about twice the number of cells of the narrower parasegments. The total width and number of cells in all four parasegments is equivalent to wild type. Each of the narrow parasegments maintains a constant relative width until around stage 12. After this time they decrease further in both width and cell number. The wide parasegments remain about 1.3-1.5 times wider and contain about 1.4 times as many cells as a normal parasegment.
Ectopic expression between 2.5 and 3 hours of development causes pair rule deletion in the pattern of cuticular structures formed at the end of embryogenesis.
Ectopic ftz expression causes severe pattern defects.
The dorsal pattern of embryos in which ftzhs.PS has been expressed during the blastoderm stage using heat shock indicates that the apparent segments have a mixed segmental character. The 'A1-like' segment includes the posterior row of dorsal hairs characteristic of pA2 (posterior second abdominal segment). The anterior band of dorsal hairs in the 'T2-like' segment extends past the dorsal sense organs as is usually found in pT3 (posterior third thoracic segment).
Ectopic expression between 2.5 and 3.5 hours of development causes a pair rule phenotype. Larvae show deletion of even numbered segments. Heat induction after blastoderm stage or during embryogenesis does not give a pair rule phenotype.