Fig. 2: Principal component analysis (PCA) of the metabolic profiles of 14 different lamprey tissues.

a PCA score plots of the metabolic profiles acquired at positive and negative ion modes, respectively (n = 3 for each tissue except that n = 5 for QC samples). b Hierarchical clustering heatmaps of the metabolic profiles acquired at positive and negative ion modes, respectively (n = 3 for each tissue except that n = 5 for QC samples). Each row represents a sample, and each column represents a metabolite. Each colored cell (red higher, blue lower) on the map corresponds to a z-score normalized mass feature.