Ectopic expression of pb^Q50K.hs using heat shock results in ectopic sex combs, tarsus to arista transformations and twisted legs.

Heat induced expression in wild type does not affect proboscis formation. Heat induced expression in pb²⁷/pb²⁰ mutants at 36.5^oC for 15-30 minutes between 67 and 72 hours AEL transforms the tarsal mouthparts to arista. Transformation is not associated with pseudotrachea formation. Ectopic expression of Scr^hs.PP results in the formation of ectopic T1 beards in T2 and T3, coexpression with pb^Q50K.hs suppresses T1 beard formation in all three thoracic segments. Ectopic expression at late second and early third larval instar stage by a 10 or 20 minute heat shock is very toxic. Survivors exhibit a number of leg phenotypes: increased number of sex combs on male first legs, ectopic sex comb on lower tarsal segments of the first leg, a twisted and shortened leg phenotype and a tarsus-to-arista transformation at the ends of all tarsi.

Heat shock to embryos results in inhibition of germ-band retraction, inhibition of head involution, and a reduction of the T1 beard. One short heat shock of 15-30 mins between 64-72 hrs after egg laying causes shortening of the first leg, increase in the number of sex combs and induction of extra sex combs on the lower tarsal segment of the first leg. All six legs show tarsal to aristal transformations.