Heat-map matrices of metabolite correlation in (A) WT, (B) mto1 , and (C) tt4. The metabolites are classified into 6 groups: amino acids, fatty acids, organic acids, N-containing compound, sugars, steroids and unknown compounds. Each square indicates r
(Pearson's correlation coefficient of a pair of metabolites), and the value of r
is represented by the intensity of blue or red colors as indicated on the color scale.