Dropping like flies: environmentally induced impairment and protection of locomotor performance in adult Drosophila melanogaster.

In Drosophila, heat shock (HS) during the pupal stage chronically hinders adult locomotor performance by disrupting wing development and cellular and/or tissue-level mechanisms that support walking and flight. Furthermore, heat pretreatment (PT) protects locomotor function against these disruptions. HS flies with abnormal wings were less able to alter trajectory in free fall relative to control, PT-only, and PT+HS wild-type flies. This deficit was less severe but still present in HS-only flies with wild-type wings. Transgenic increases in the copies of genes encoding the major inducible heat-shock protein of Drosophila melanogaster, Hsp70, also protected walking ability from disruption due to pupal HS. Walking velocity did not differ between excision (five natural hsp70 copies) and extra-copy (five natural and six transgenic hsp70 copies) flies in the control, PT, and PT+HS groups, nor did velocity vary among these thermal treatment groups. HS dramatically reduced walking velocity, however, but this effect occurred primarily in the excision flies. These results suggest that Hsp70 and other mechanisms protect against heat-induced locomotor impairment.