Tracheal invagination initiates in rho7M43 btlLG19 double mutants, but rotation of dorsal cells does not occur, as in rho7M43 single mutants. However, a finger-like structure is never formed, instead, the tracheal cells remain as a cavity.
Expression of Mkp3GS801 under the control of Scer\GAL4btl.PS in a btlLG19/+ background does not affect the penetrance of the Scer\GAL4btl.PS>Mkp3GS801 branch integrity phenotype but results in a significant increase in failure of branch formation.
Expression of btl::tor4021.Scer\UAS under the control of Scer\GAL4btl.PS in btlLG19 mutant embryos partially rescues tracheal cell migration, and additional tracheal branching is seen, as in embryos expressing btl::tor4021.Scer\UAS under the control of Scer\GAL4btl.PS in a wild-type background. Expression of Ras85DV12.Scer\UAS under the control of Scer\GAL4btl.PS in btlLG19 mutant embryos partially rescues tracheal morphogenesis. Expression of phl::tor13D.hs.sev in btlLG19 mutant embryos partially rescues tracheal morphogenesis.
Multiple heat shocks of the constitutively active btl::tort4021b.hs.sev protein can partially rescue tracheal migration in homozygous embryos, a single early heat shock allows reduced correction of the mutant phenotype. Partial rescue can also be achieved by the constitutively active proteins tor13D.hs.sev, Ras85DQ13.hs, phl::tor13D.hs.sev, sev::tor13D.hs.sev, Egfr::tort4021E.hs.sev and htl::tort4021F.hs.sev.