Figure 3.

Flies lacking iPLA2-VIA have reduced mitochondrial membrane potential and decreased mitochondrial respiratory chain activity. (A) The mitochondrial membrane potential measured using TMRM fluorescence in the brains of 25-day-old flies was significantly decreased in iPLA2-VIA^−/− brains compared to w¹¹¹⁸ controls (***P < 0.001; n = 6 brains for each genotype). (B) The respiratory chain activity was measured by assessing oxygen consumption and demonstrated that mitochondria from young Day 2 and old Day 32 iPLA2-VIA^−/− flies have reduced complex I and II–dependent respiration compared with w¹¹¹⁸ control flies, manifested as significantly decreased oxygen consumption in state 3 respiration (*P < 0.05, **P < 0.001). (C) The respiratory control ratio was significantly lower in iPLA2-VIA^−/− mitochondria compared with age-matched control w¹¹¹⁸ mitochondria. Furthermore, the respiratory control ratio of iPLA2-VIA^−/− flies in the presence of glutamate/malate was dependent on the age of the flies: older flies having lower respiratory control ratio values (*P < 0.05, **P < 0.001).