Figure 4.

Comparative metabolic pathway analysis. (a) Analysis of the metabolic profiles resulting from D. rerio injected by 70 μg malic acid provides a better insight into the effects of 90 significant metabolites (p < 0.01). Based on the KEGG compound (http://www.kegg.jp/kegg/compound/), metabolic network pathways in D. rerio are further analyzed with iPath2.0 (http://pathways.embl.de/iPath2.cgi). Red and blue lines represent increase and decrease in the malic acid group, respectively. (b) The activity of a-ketoglutaric dehydrogenase (KGDH) and succinate dehydrogenase (SDH). Twenty zebrafish spleens were collected in each group. Five were pooled as a sample, yielding four biological repeats for analysis of enzyme activity. Samples were collected in 24 h after the injection of malate for 3 days. Results (b) are displayed as mean ± SEM, and significant differences are identified (*p < 0.05, **p < 0.01) as determined by two-tailed Student’s t-test.