Expression of tmod^hs.PDL using heat shock during mid-to-late pupation interferes with flight, whereas expression of tmod^hs.PDL using heat shock during early pupation has no significant effect on flight ability. Expression of tmod^hs.PDL using heat shock on day 4 after puparium formation results in shorter thin filaments in the core of indirect flight muscle (IFM) myofibrils compared to those thin filaments at the periphery. Expression of tmod^hs.PDL using heat shock during myofibril assembly appears to irreversibly prevent elongation of preexisting thin filaments during IFM development. Sarcomere lengths and myofibril diameters in heat-treated tmod^hs.PDL flies are similar to those in control flies. The Z-discs are slightly crooked. Electron dense particles are present in the core of myofibril, adjacent to the M line. Many myofibrils are missing a small population of thick filaments. In cross section, in some myofibrils, thin filaments are not visible in the core.

tmod^hs.PDL is a suppressor of embryonic peripheral nervous system & glial cell | supernumerary phenotype of spdo^H7