Chitwood, D.J., Insect Physiology Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, 20705, MD, United States
Lusby, W.R., Insect Physiology Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, 20705, MD, United States
Lozano, R., Insect Physiology Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, 20705, MD, United States
Thompson, M.J., Insect Physiology Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, 20705, MD, United States
Svoboda, J.A., Insect Physiology Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, 20705, MD, United States

The metabolism of various dietary sterols and the effects of an azasteroid on sitosterol metabolism in the free-living nematode Caenorhabditis elegans was investigated. The major unesterified sterols of C. elegans in media supplemented with sitosterol, cholesterol or desmosterol included 7-dehydrocholesterol (66.5%, 40.5%, 31.2%, respectively), cholesterol (6.7%, 52.3%, 26.9%), lathosterol (4.4%, 3.6%, 1.7%) and 4α-methylcholest-8(14)-en-3β-ol (4.2%, 2.1%, 3.8%). Esterified sterols, representing less than 20% of the total sterols, were somewhat similar except for a significantly higher relative content of 4α-methylcholest-8(14)-en-3β-ol (23.3%, 23.4%, 10.6%). Thus C. elegans not only removes the substituent at C24 of dietary sitosterol but possesses the unusual ability to produce significant quantities of 4α-methylsterols. When C. elegans was propagated in medium supplemented with sitosterol plus 5 μg/ml of 25-azacoprostane hydrochloride, the azasteroid strongly interfered with reproduction and motility of C. elegans and strongly inhibited the Δ24-sterol reductase enzyme system; excluding sitosterol, the major free sterols of azacoprostane-treated C. elegans were cholesta-5, 7, 24-trien-3β-ol (47.9%), desmosterol (9.4%), fucosterol (2.1%) and cholesta-7,24-dien-3β-ol (2.0%). These 4 sterols are likely intermediates in the metabolism of sitosterol in C. elegans. © 1984 American Oil Chemists' Society.