Figure 3.Metabolic changes and associated affected pathways in aged mouse brain using global metabolomic approach(A) A cloud plot showing differentially expressed metabolite features (bubbles) across different regions of brain (level of significance: p ≤ 0.01, Intensity > 20,000 ion counts). Metabolite features are projected depending on their m/z ratio and retention time along HILIC gradient. The color of the bubble indicates the level of significance (p-value), with darker color (in blue tones) representing more significant changes (lower p-values). The size of the bubbles is an indicator of ion intensity. A Total Ion Chromatogram (HILIC –ESI MS) is shown in the background. (B) Predicted metabolic activity network in healthy aging brain directly from m/z feature table. Network is defined by 4 subnetworks or modules represented by glutamate, AMP, NAD and GDP-GTP that show more internal connections than expected randomly in the whole network. Metabolites are colored according to their p-values and intensities represented above in the cloud plot. Not significantly altered metabolites are represented by transparent bubbles and were included for network connectivity. (C) Metabolite set enrichment analysis (MSEA) for mammalian species based on a library containing 88 groups of biologically meaningful metabolite sets. Pathways are ranked depending on the overlap of identified significantly dysregulated metabolites (IDs validated by MS/MS analysis) and total metabolites present in the reference pathway (Table S6).
