Melibiosylceramide as the Sole Ceramide Dihexoside from the Eggs

Melibiosylceramide (Galal-6Glc£l-lCer) was found as the sole ceramide dihexoside from the eggs of the sea urchin, Anthocidaris crassispina. Ceramide monohexoside of the eggs consisted only of glucosylceramide (Glc£l-lCer). These lipids were purified by successive column chromatographies on DEAE-Sephadex A-25, silicic acid and Florisil, and identified by gas-liquid chromatography, negative-ion fast atom bombardment mass spectrometry and proton nuclear magnetic resonance spectroscopy as well as methylation analysis. Long-chain base compositions of both lipids were almost identical and comprised n-CI8-phytosphingosine and small amounts of its homologs (C17-C,9). Fatty acid compositions were qualitatively very similar, but the glucosylceramide contained more 2-hydroxy fatty acid than the melibiosylceramide. Although the chain length of fatty acids was distributed over a wide range, six major fatty acids, namely 22:1, 23:1, 24:1, 22h:l, 23h:l and 24h:l, constituted more than 92 % of the fatty acid content in these lipids. Neutral glycosphingolipids of invertebrates have been investigated to a limited degree in a starfish, molluscs and flies; except for the starfish, Asterina pectinifera (1), the