Characterization of Metabolite Compositions in Wild and Farmed Red Sea Bream ( Pagrus major) Using Mass Spectrometry Imaging.

Nutritional profiles and consumer preferences differ between wild and farmed fish, and identification of fish sources can be difficult. We analyzed the metabolite molecules of wild and farmed red sea bream ( Pagrus major) to identify specific metabolic differences. The total lipid content and molecular composition of wild and farmed red sea bream muscles were analyzed using thin-layer chromatography and mass spectrometry imaging. Triacylglycerol levels were significantly higher in farmed fish. Wild fish contained saturated-fatty-acid-containing triacylglycerols as a major molecular species, while docosahexaenoic-acid-containing triacylglycerol levels were significantly higher in farmed fish than in wild fish. The localization of each muscle-fiber-type-specific marker demonstrated that wild fish exhibit myosin heavy chain (MHC)-type-IIb-specific phospholipids, while farmed fish exhibit MHC-type-IIa-specific phospholipids in their white muscle. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analyses separated the identified myosins and revealed that farmed fish possess additional myosin isoforms when compared to wild fish. In addition, we found a farmed-fish-specific distribution of anserine in their white muscle. These molecules can be used as new molecular markers for determining the geographic origins of wild versus farmed red sea bream.