|Lusby William R|
|Howarth Oliver W|
Submitted to: Journal of Biological Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/1995
Publication Date: N/A
Citation: N/A Interpretive Summary: Nematodes are microscopic worms that annually reduce U.S. agricultural productivity by eight billion dollars. Because safe and selective methods for controlling nematodes are not available, ARS scientists are looking for new control strategies. Because human beings and other mammals have different hormones than nematodes, one safe method could be the disruption of hormonal systems within nematodes. Indeed, ARS scientists have previously shown that some chemical compounds that disrupt hormone biochemistry in insects also destroy the ability of nematodes to reproduce. Therefore, a search was begun to find insect hormones in nematodes, and the present paper reports research about whether nematodes produce the same hormones found in insects. One nematode compound that chemical tests initially indicated was an insect hormone in fact turned out to be a complex type of fat called a glycolipid. This paper focuses upon the rather complex experiments used to chemically identify this glycolipid. Remarkably, the glycolipid has a different structure than similar compounds in insects, mammals or plants. Therefore, the results indicate that it may be possible to selectively and safely interfere with the life cycles of nematodes by disrupting their ability to make glycolipids. Thus, the results will be utilized by scientists interested in developing innovative strategies for managing plant-parasitic nematodes.
Technical Abstract: Caenorhabditis elegans was cultured in semidefined medium containing yeast extract, soy peptone, glucose, hemoglobin, Tween 80, and sitosterol. Monoglycosylceramides were chromatographically purified from nematode extracts. Their structures were elucidated with mass spectrometry, nuclear magnetic resonance spectroscopy, and analysis of methanolysis products of the parent cerebrosides. The glycosylceramides were unusual in that the only long chain sphingoid base detected was an iso-branched 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 to C-26 acids; some iso-branched analogs also occurred. The sphingomyelins of C. elegans were also hydrolyzed, and the same iso-branched C17 compound was the only sphingoid base detected. This is the first structural analysis of a nematode glycosphingolipid and the first report of an organism in which the long chain sphingoid bases are entirely iso-branched.