Polytene chromosomes normal.
Embryos hemizygous for gtQ292 and homozygous for tsh8 show normal lobe-like morphology of the labial segment. The dorsal ridge is enlarged, but is separate from the labial segment in late-stage mutant embryos.
Expression of tioScer\UAS.cLa, under the control of Scer\GAL469B, partially rescues the denticle row phenotype of tsh8 mutants at 25oC, but fails to rescue this phenotype at 22oC. At 25oC, the partially-rescued larvae have five denticle rows, but types 1 and 2 are missing and types 3-6 are not in the same sequential order seen in wild-type larvae. The identity of the T1 segment is restored, shown by the presence of a T1 beard. However, expression of tioScer\UAS.cLa causes a new phenotype: ectopic denticles appear in the head region.
The denticle types present (5 and 6) in tsh8 mutant embryos are unchanged if they are also expressing hhScer\UAS.cIa under the control of Scer\GAL4prd.RG1, although in some segments the denticle belts are reduced and the shape of the denticle belt is modified. Cuticle from tsh8 ; ci94 double mutant embryos produces only weakly pigmented, type 5 denticles and no naked cuticle.
At 22oC, the presence of Mmus\Sdccag33Scer\UAS.T:Hsap\MYC and Scer\GAL469B results in partial rescue of the T1 segment and trunk cuticle phenotypes of tsh8/tsh8 embryos. At 29oC this rescue is more complete. At 22oC, the presence of Mmus\Sdccag33lScer\UAS.T:Hsap\MYC and Scer\GAL469B leads to little or no rescue of the segment transformations apparent in the cuticle phenotype of tsh8/tsh8 embryos. However, at 29oC this phenotype is partially rescued. At 22oC, the presence of Mmus\Zfp537Scer\UAS.T:Hsap\MYC and Scer\GAL469B results in partial rescue of the T1 segment and trunk cuticle phenotypes of tsh8/tsh8 embryos. All these larvae show significant but incomplete rescue of the T1 denticle belt phenotype but none of them displays beard-specific denticles. The size of the naked cuticle bands in the trunk appears normal. At 29oC this rescue is more complete.
Expression of tshScer\UAS.cGa at 22oC, under the control of Scer\GAL469B, rescues the denticle and naked cuticle phenotype of tsh8 mutants and Ti segment identity is restored. However, this expression induces ectopic denticle formation in the head region.