Submitted to: Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: April 3, 2008
Publication Date: April 8, 2008
Citation: Chitwood, D.J., Skantar, A.M. 2008. Progress in nematode steroid research [abstract]. Abstracts, Plant Parasitic Nematodes: Biodiversity, Study, Collections. p. 22. Technical Abstract: An obvious approach to developing biorational approaches to nematode control involves the exploitation of metabolic differences between host and parasite. In the case of nematodes, one obvious metabolic difference from their plant or mammalian hosts is the absence in nematodes of the ability to biosynthesize sterols de novo. This nutritional requirement for sterol results in parasitic nematodes needing to obtain sterols from their hosts and subsequently metabolize them to other sterols and steroids required for nematode growth, development and reproduction. Consequently, nematode-specific steroid metabolic pathways provide attractive targets for disrupting the life cycles of these parasites. We have conducted many investigations with Caenorhabditis elegans as a model organism for examining sterol biochemistry in plant-parasitic nematodes. The most remarkable sterol metabolic transformation of C. elegans is the introduction of a methyl group at C-4 on the sterol nucleus by a pathway seemingly present in nematodes alone. C. elegans also removes the ethyl or methyl groups present at the C-24 position in the sterol side chain, and the delta24-sterol reductase can be inhibited by azasteroids. The C. elegans let-767 gene encodes a protein similar to mammalian enzymes that reduce 17-beta-hydroxysteroids. We have identified two homologues of let-767 in the soybean cyst nematode, Heterodera glycines. These genes, Hg-hsd-1 and Hg-hsd-2, share similarity to 17-beta-hydroxysteroid dehydrogenases involved in mammalian steroid hormone biosynthesis.