Adult flies are stress sensitive; when subjected to mechanical shock they become paralysed. Mosaic analysis reveals separate mesodermal foci for this phenotype. Adults show temperature-sensitive lethality; they die 2-12 days after eclosion at 29^oC. There is also a temperature-sensitive semi-lethal period during preimaginal development.

Adults briefly paralyzed after movement, especially when they are induced to move rapidly; recovery occurs within one min, followed by uncoordinated movements and a period refractory to induction of further paralysis of at least one hr (Grigliatti et al., 1973); rex is temperature-sensitive for lethality, i.e., as induced by holding adults about ten days at 29^oC (Homyk et al., 1979); also there are semi-lethal effects on development [i.e., ca. 50% viability after rearing at 29^oC (Homyk, Sinclair, Wong and Grigliatti, 1986). rex also hypersensitive to killing effects of caffeine (Homyk et al., 1979). Causes an abnormally slow recovery from blue-light induction of prolonged depolarizing afterpotential (PDA) of photoreceptors; recovery induced rapidly by orange light (Homyk and Pye). Mosaic analysis of leg paralysis induced by rex suggests mesodermal (possibly muscle) foci, separate focus for each leg (Homyk et al., 1986).