Unsaturated fatty acids profiling in live C. elegans using real-time NMR spectroscopy

Unsaturated fatty acids (UFAs) impact central cellular process in animals such as membrane function, development and disease. Perturbations of UFAs homeostasis contribute to the onset of metabolic, cardiovascular and neurodegenerative disorders. Nevertheless, links between lipid desaturation fluctuations and the dynamics of mono and polyunsaturated fatty acid synthesis in live animal physiology are poorly understood. To advance in the understanding of this process, we decided to study de novo UFAs synthesis with the highest resolution possible in live Caenorhabditis elegans. Conventional lipid analysis in this organism involves solvent extraction procedures coupled with analytical techniques such as chromatography and/or mass spectrometry. These methodologies are destructive and prevent the access of information, linking in vivo UFA dynamics and functionality. To overcome these limitations, we used uniform 13C isotope labeling and real-time 2D heteronuclear NMR spectroscopy in live C. elegans to identify their UFA compositions and the dynamic response of these fatty acids during cold adaptation. Our methodology allowed us to monitor in real time the upregulation of UFA synthesis when ambient temperature is decreased. The analysis of UFAs synthesis in worms lacking the adiponectin receptor AdipoR2 homolog PAQR-2 during a temperature drop supports the pivotal role of this protein in low temperature adaptation and survival. Our results provide new insights about the environmental regulation of UFAs and establish methodological benchmarks for future investigations of fatty acid regulation under experimental conditions that recapitulate human diseases.