Shotgun lipidomics and mass spectrometry imaging unveil diversity and dynamics in lipid composition inGammarus fossarum

Summary Sentinel species are playing an indispensable role in monitoring environmental pollution in aquatic ecosystems. Many pollutants found in water prove to be endocrine disrupting chemicals that could cause disruptions in lipid homeostasis in aquatic species. A comprehensive profiling of the lipidome of these species is thus an essential step towards understanding the mechanism of toxicity induced by pollutants. We here extensively examined both the composition and spatial distribution of lipids in freshwater crustacean Gammarus fossarum . The baseline lipidome of gammarids of different gender and reproductive stage was established by high throughput shotgun lipidomics. Spatial lipid mapping by high resolution mass spectrometry imaging led to the discovery of sulfate-based lipids in hepatopancreas and their accumulation in mature oocytes. We uncovered in G. fossarum a diverse and dynamic lipid composition that deepens our understanding of the biochemical changes during development and which could serve as a reference for future ecotoxicological studies.