Figure 8 .

dp32^EC1 mutant retains wild-type mitochondrial membrane potential (ΔΨm) and ATP production. (A, B) ΔΨm measurements using tetramethylrhodamine ethyl ester perchlorate (TMRE) and GFP targeted to the mitochondrial matrix (mito-GFP). (A) Examples of live confocal images of TMRE at DLM neuromuscular synapses exhibiting neuronal expression of UAS-mito-GFP in a WT or dp32^EC1 genetic background. Mito-GFP serves as a mitochondrial marker within presynaptic terminals. (B) dp32^EC1 retains wild-type ΔΨm. The ratio of TMRE to GFP (TMRE/GFP) from the same region of interest was used to represent the relative ΔΨm, which should be independent of mitochondrial size, shape, and orientation. The relative ΔΨm from dp32^EC1 is shown as a mean percentage of that from WT. The ΔΨm in dp32^EC1 is not significantly different from WT at either temperature. The respective ratios of TMRE to GFP at WT and dp32^EC1 synapses were 1.32 ± 0.11 (n = 26) and 1.30 ± 0.11 (n = 23) at 20°. The corresponding values at 36° were 0.60 ± 0.06 (n = 22) and 0.56 ± 0.05 (n = 24). (C) Head homogenates from dp32^EC1 contain wild-type levels of ATP. Head homogenates prepared from WT and dp32^EC1 flies were exposed to 38° for 10 min and subjected to a luciferin-luciferase ATP detection assay. The relative ATP levels were calculated by dividing the luminescence by the total protein concentration. The relative ATP levels in WT and dp32^EC1 were 1.28 ± 0.24 nmol/mg protein (n = 5) and 1.27 ± 0.23 nmol/mg protein (n = 5), respectively, and not significantly different.