THE GLYCOSYLCERAMIDES OF THE NEMATODE CAENORHABDITIS-ELEGANS CONTAIN AN UNUSUAL, BRANCHED-CHAIN SPHINGOID BASE

Caenorhabditis elegans was cultured in semi-defined medium containing yeast extract, soy peptone, glucose, hemoglobin, Tween 80, and sitoste rol. Monoglycosylceramides were chromatographically purified from nema tode extracts. Their structures were elucidated with mass spectrometry , nuclear magnetic resonance spectroscopy, and analysis of methanolysi s products of the parent cerebrosides. The glycosylceramides were unus ual in that the only long-chain sphingoid base detected was an iso-bra nched compound with a C-4 double bond (i.e., 15-methyl-2-aminohexadec- 4-en-1,3-diol). Glucose was the only sugar moiety detected. The fatty acids consisted of a series of primarily straight-chain, saturated, 2- hydroxylated C-20-C-26 acids; some iso-branched analogs also occurred. The sphingomyelins of C. elegans were also hydrolyzed, and the same i so-branched C-17 compound was the only sphingoid base detected. This i s the first structural analysis of a nematode glycosphingolipid and th e first report of an organism in which the long-chain sphingoid bases are entirely iso-branched.