LIPID COMPOSITION OF THE BLUBBER OF MARINE MAMMALS: INFLUENCE OF GENETIC AND ENVIRONMENTAL FACTORS

participantMarine mammals are recognized as good indicators of environmental quality and changes in marine ecosystems. Their blubber is particularly interesting to study in this context. The composition of this adipose tissue has been shown to depend on genetic as well as ecological parameters, and to reflect diet specificity and availability. The blubber is specific to most marine mammals and shows a polyphyletic origin, which reinforce its importance. Multifunctional, it is a fundamental parameter of the mammalian adaptation to the aquatic environment. For the first time in marine mammals, we have developed a NMR HR-MAS (High-Resolution Magic Angle Spinning) analysis approach, which we applied to the study of the lipid blubber composition of more then 70 cetaceans and pinnipeds stranded in Brittany in the last five years. 1H NMR spectra showed a high degree of resolution, and samples can be analyzed fresh, frozen or even conserved in 95% ethanol. All the peaks detected corresponded to different functions of triacyglycerols excepted for deep diving cetaceans where HR-MAS spectra detected only wax esters. Fatty acids can also be studied more precisely: first, two short ramified FA, isovaleric and isobutyric acids, were detected. Although their accumulation is toxic for all other mammals, they are strongly present in the blubber of some cetaceans, including the harbour porpoise, the bottlenose and the common dolphins. For the other FA, mean lengths, unsaturation proportions and omega 3 presences can be quantified and compared. Intra- and inter-specific differences of these parameters have been analyzed, and data will be shown. The following of this work will consist in a more precise characterization of the influence of environmental conditions on FA blubber composition