Figure 1. (A) Mitochondrial electron transport chain proteins that we found to be more highly expressed in the old are indicated in red by their location (Complex II, IV, and V) in the cartoon schema. (B) Gene pathways identified for proteins upregulated in the old using DAVID to convert protein identifiers to their genes (DAVID Bioinformatics Resources 6.7 (https://david.ncifcrf.gov). These genes fall into pathways related to oxidative phosphorylation, neurodegenerative disease, and integration of energy metabolism (Oxidative phosphorylation [16 from KEGG pathway database], Neurodegenerative disease [16 from KEGG], Cardiac muscle contraction [6 from KEGG], Integration of energy metabolism [16 from REACTOME pathway database], Diabetes [16 from REACTOME], Metabolism of nucleotides [8 from REACTOME]).