Evaluation of the fatty acid profile of sea lamprey muscles

Northern lampreys belong to the family Petromyzontidae and six of the thirty eight species known occur in Portugal. The sea lamprey (Petromyzon marinus, L.), together with the Mixines, constitute the only two groups of vertebrates without jaws (Agnatha) with its origin in the Paleozoic era, 400-500 million years ago [1]. These groups are considered living fossils, since they have no significant morphological changes from current individuals. However they presented high capacity to adapt to different environmental conditions, which has given them persistence over time. The sea lamprey life cycle contains a microphagic larval phase, which is spent in freshwater. In this phase, larvae feed mostly on microorganism and organic particles in suspension in water column. After four to seven years, a metamorphosis period occurs which transforms the microphagic filter-feeding larvae into pelagic juveniles. This is a non-trophic period. Finally, juveniles migrate downstream to sea, feeding on blood of several marine species for as much as 13 months [1,2]. Thus, the characterization of fatty acids in sea lamprey muscle will infer if there is a fatty acid profile that remains stable throughout the life-cycle, regardless of the development phase, diet and environment [2]. In this study 30 specimens of sea lamprey (15 juveniles and 15 adults) from Mondego river basin were used. The juveniles were captured in October during the beginning of downstream migration, and the adults were captured at the estuary mouth at the beginning of the spawning migration (March). For each individual, a small muscle portion was collected and lyophilized until constant mass and then aliquots of a 200 mg-portion of lyophilized muscle samples were used for analysis. The total lipids were obtained from accelerated solvent extraction (ASE), followed by saponification and methylation with boron trifluoride (BF3) in 14% methanol [3]. The samples were analyzed by gas chromatography coupled with mass spectrometry (GC/MS) in order to characterize muscle total lipids fatty acids profile.ACKNOWLEDGMENTS This work was financially supported by Foundation for Science and Technology (FCT): project PTDC/BIA-BEC/103258/2008 and project UID/MAR/04292/2013 (national funds FCT/MEC - PIDDAC through Acordo de Parceria PT2020)