Sphingomyelins in Four Ascidians, Ciona intestinalis, Halocynthia roretzi, Halocynthia aurantium, and Styela clava

Sphingomyelin is rarely found in lower animals, while sphingophospholipid is a characteristic of higher animals. In this study, sphingomyelin was first isolated and characterized from ascidian Ciona intestinalis. Ascidian sphingomyelin was prepared using ion exchange (QAE-Sphadex-A25) and silicic acid (Florisil and Iatrobeads) column chromatographies. The chemical structure was characterized by fatty acid analysis, sphingoid analysis, hydrogen fluoride degradation, acid hydrolysis, enzymatic hydrolysis, infrared analysis, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The ceramide moieties of C. intestinalis sphingomyelin consisted primarily of C16:0, C18:0, and C18:1 fatty acids and d18:2 sphingadiene. Furthermore, sphingomyelins were isolated and characterized from 3 other ascidians, Halocynthia roretzi, Halocynthia aurantium, and Styela clava using the same methods. Comparative analysis of the sphingomyelin structures in 4 ascidian species-C. intestinalis (Enterogona) and H. roretzi, H. aurantium, and S. clava (Pleurogona)-revealed that the major fatty acid composition of the ceramides was similar, and that they differed in minor components.