Betaine lipids in chlorarachniophytes

P>Evolving from the endosymbiosis of a green algal cell by a filose amoeba or amoeboflagellate, the chimearic chlorarachniophytes combine unique features retained from both of their ancestral units. They have preserved from the endosymbiont only the nucleomorph and chloroplast. Four strains from three genera of this algal class were studied to identify a set of non-phosphorous-containing polar lipids and their associated fatty acids using the techniques of positive-ion electrospray ionization/mass spectrometry (ESI/MS) and electrospray ionization/mass spectrometry/mass spectrometry (ESI/MS/MS). Fourteen non-phosphorous-containing polar lipids, classified as betaine lipids were primarily identified as forms of diacylglyceryl-N,N,N-trimethylhomoserine (DGTS) and its structural isomer diaclyglycerylhydroxymethyl-N,N,N-trimethyl-beta-alanine (DGTA). Though the number of forms of DGTA and DGTA were roughly equal, DGTS composed more of the polar lipid portion present in three of the strains tested, while the fourth, Lotharella globosa, was dominated by forms of DGTA. In addition, a lipid tentatively identified as diacylglycerylcarboxyhydroxymethylcholine (DGCC) was observed twice in minor amounts. The polar lipid-associated fatty acids of the aforementioned algal strains generally included dodecanoic acid (12:0), tetradecanoic acid (14:0), hexadecanoic acid (16:0), octadecanoic acid (18:0), octadecenoic acid (18:1), and eicosapentaenoic acid [20:5(n-3)]. The differences in betaine lipid content among the species studied may allow for further conclusions to be drawn regarding the taxonomy of chlorarachniophytes.