Altered autophagy flux response to fasting in young Ulk1 MKO muscles. (A) Quantification of total red fluorescence intensity in fasted and control MKO and LM muscles (Main effect of fasting, p = 0.003). (B) Green:Red fluorescent protein ratio after fasting compared to control levels of autophagosome degradation in Ulk1 MKO and LM muscles, Significant interaction (p = 0.006) All data are presented as mean ± SEM * = significantly different from both control groups, # = significantly different from LM control. Representative two photon z-stack images taken from the TA muscle of (C) LM control, (D) LM fasted, (E) MKO Control, (F) MKO fasted mice. Green = LC3II incorporated into autophagosome membrane, Red = LC3II in cytosol, Blue = second harmonic generation labeling skeletal muscle contractile proteins for identifying muscle fiber location.