Figure 2. Flies overexpressing Ldh have increased mRNA levels, LDH activity, elevated lactate, and shortened lifespan. (A) Ldh mRNA levels were significantly increased in the heads of young and old tim>Ldh compared to age-matched tim>w control flies. Values are reported as a percentage of expression relative to age-matched tim>w set to 100% (n=4). (B) LDH enzyme activity was significantly increased for the pyruvate to lactate reaction in the heads of 55-day old tim>Ldh flies compared to tim>w controls (n=4). (C) Lactate concentrations were significantly higher in the heads of tim>Ldh flies compared to age-matched tim>w controls (n=4). Error bars in A-C indicate SEM. Statistical significance was determined by Unpaired t-test with Welch’s correction (***p<0.001; **p<0.01; *p<0.05). (D) Survival curves of tim>Ldh (n=193) and tim>w (n=170) males. Median lifespan was significantly reduced in tim>Ldh flies compared to control (Gehan-Breslow-Wilcoxon test; p<0.0001).