Expression of Sb^hs.PB using heat shock at 0 or 3 hours after pupariation (AP) results in malformed legs; heat shock at 0 hours AP results in 50% of flies having malformed legs, heat shock at 3 hours AP results in 59% of flies having malformed legs. Prepupal heat shocks after 4 hours AP do not result in a malformed leg phenotype.

Expression of Sb^hs.PB using a double heat shock at 30 hours and 33 hours AP results in all segments of all legs being shortened, with the severity of the phenotype increasing on a distal-to-proximal axis. First and third legs are more severely affected than second legs. Defects are also seen in the dorsal thorax, including a mild cleft and disorientation of the bristles. Bristle morphology and length is normal in these flies.

Expression of Sb^hs.PB using heat shock at 27.5 hours AP results in a slight shortening of prothoracic femurs.

Expression of Sb^hs.PB using heat shock after 42 hours AP does not result in abnormal leg or thoracic phenotypes.

Expression of Sb^hs.PB in a wild-type background using a 1 hour 37^o heat shock in staged 0 hour or 3 hour prepupae results in a high frequency of severe leg malformation in adults, involving the second and third pair of legs. Overexpression of Sb^hs.PB either 12 hours before or 12 hours after pupariation does not affect leg morphogenesis.