Skeletal Muscle Lipidomics as a New Tool to Determine Altered Lipid Homeostasis in Fish Exposed to Urban and Industrial Wastewaters

This work applies ultrahigh performance liquid chromatography coupled with high-resolution mass spectrometry (UPLC-HRMS) to characterize for the first time the lipidome of the skeletal muscle of two fish species (Barbus meridionalis, Squalius laietanus) collected in a Mediterranean River affected by urban and industrial wastewater outflows. The untargeted analysis allowed a clear separation of the lipidome of fish from polluted and reference sites; phosphatidylcholines (PCs), phosphatidylethanolamines (PEs), and their lyso and ether-linked forms were among the distinctive features. The targeted analysis consistently detected a decrease in PC-plasmalogens (36:4, 36:6, 38:6) and highly unsaturated PCs (36:5, 36:6, 38:6, 40:6, 40:7) and an increase in plasmanyl-PCs (36:5, 38:5), lyso-PCs (16:1, 18:1, 22:4) and cholesteryl esters (CEs) (16:0, 18:0, 20:4) in fish from polluted sites. These lipid profiles were indicative of oxidative stress and dysregulation of cholesterol homeostasis in fish from polluted sites. This methodology represents a promising tool for the development of novel noninvasive diagnostic methods based on muscle tissue biopsies to assess the effects of water pollution in wildlife.