Mono- and digalactosyldiacylglycerol composition of chlorarachniophytes (Chlorarachniophyceae): production of a novel lauric acid (12:0)-containing form of monogalactosyldiacylglycerol

Chlorarachniophytes are unicellular eukaryotic algae typically found in marine habitats. Because chlorarachniophytes are hypothesized to have originated from a secondary endosymbiosis of a green algal cell by an amoeba or ;amoeboflagellate, they have garnered significant attention from those interested in endosymbiosis-mediated evolution. In comparison to the wealth of molecular data that now exist for chlorarachniophytes, very little is known about their fundamental biochemistry. To date, only one published study (Leblond et al. 2005) exists on their lipid biochemistry. This study found that chlorarachniophyte glycolipids have a simple fatty acid profile dominated by hexadecanoic acid (16:0) and eicosapentaenoic acid [20:5(n-3)]. The work presented here extends beyond their initial finding to elucidate via positive-ion electrospray ionization/mass spectrometry and electrospray ionization/mass spectrometry/mass spectrometry the intact molecular forms of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG). Two forms of MGDG and two forms of DGDG were identified, including a novel lauric acid (12:0)containing form of MGDG. 20:5/12:0 (sn-1/sn-2). not predicted by the published results of Leblond et al. (2005) and, to our knowledge. previously unreported in algae.