Characterization of lipid structures in femoral secretions of Galápagos marine iguanas by shotgun lipidomics

Abstract

The lipidome of femoral gland secretions of the marine iguana (Amblyrhynchus cristatus) was studied. The main aim of this work was to identify and quantify the lipids present in femoral secretions using mass spectrometry-based shotgun lipidomics. Lipids belonging to seven lipid classes were identified: ceramides (43.41%), triacylglycerols (42.15%), cholesteryl esters (4.18%), sphingomyelins (3.61%), phosphatidylcholines (2.67%), phosphatidylinositols (2.50%) and phosphatidylethanolamines (1.48%). The second aim of the study was to explore whether lipid composition matches the different subspecies or populations of marine iguanas. The different subspecies of iguanas did not group together in relation to their lipidome. The authors’ findings are discussed in an ecological context and compared with the results of a previous study that characterized volatile lipids in marine iguana secretions using gas chromatography. Given the high diversity of lipid structures in femoral secretions discovered in this study, it is likely that some of these could be involved in intraspecific communication. Certain lipids could have other functions, such as building a barrier to avoid water loss. More data needs to be added to explore this hypothesis. This study is the first to use a lipidomics-based approach to characterize lipid composition in lizard femoral secretions. The application of shotgun lipidomics to reptilian glandular secretions will shed new light on the potential function of lipids in intraspecific chemical communication.