UASt regulatory sequences drive expression of a full-length trh cDNA, in which the sequence of the basic domain have been changed to the sequence of the basic domain of sim. The amino acid changes are R83K, D84N and S88T.
When trhbSim.Scer\UAS is expressed ubiquitously in the embryo using Scer\GAL4hs.2sev, two additional tracheal pits are seen in additional to the 10 seen in wild-type embryos.