Lipidomic profiling reveals lipid regulation in the snow alga Chlamydomonas nivalis in response to nitrate or phosphate deprivation

The snow alga Chlamydomonas nivalis in the exponential phase was subjected to nitrate or phosphate deprivation for 0–72 h to study its stress responses in lipid profiles analyzed by UPLC/Q-TOF-MS (ultra performance liquid chromatography/quadrupole-time of flight-mass spectrometry). Three clusters were distinguished as the control, nitrate-deprived and phosphate-deprived groups in OPLS-DA (orthogonal projection on latent structure discriminant analysis) score plots based on their lipidome data. Altogether, the lipidomic approach identified twenty-two ions in nitrate-deprived group including nine l, 2-diacylglyceryl-3-O-4′-(N, N, N-trimethyl)-homoserine (DGTSs), one phosphatidylethanolamine (PE), two monogalactosyldiacylglycerols (MGDGs), four digalactosyldiacylglycerols (DGDGs), three phosphatidylglycerols (PGs), two sulfoquinovosyl-diacylglycerols (SQDGs) and one phosphatidylinositiol (PI), and nineteen ions in phosphate-deprived group including four DGTSs, one PE, one MGDG, seven DGDGs, three PGs, two SQDGs and one PG as “differentiating lipid biomarkers”. Moreover, the common and specific biomarkers were found in the two nutrient deprived groups by SUS (shared and unique structure) plot. Biomarkers-based z-score plot and heat map further showed how lipid biomarker expressions deviate from the control. The up- or down-regulation of these lipid biomarkers provided new insights into the lipid metabolism of the snow alga in response to nitrate or phosphate deprivation stress condition.