Axenic a d synchronous cultures of Caenorhabditis elegans. Nematologica, 24

A technique to axenize cultures of Caenorhabditis elegans on a large scale is described. This procedure has enabled the isolation of eggs of C. elegans in quantities sufficient to perform bio-chemical tests. Adults from monoxenic cultures were used to isolate eggs. When egg-bearing worms were suspended for 2-3 hr at 25o in an alkaline (0.4 M) solution of NaOH, the worm cuticle was partially digested, releasing free eggs. The high alkalinity rendered the eggs bacteria-free. Eggs were then isolated from a linear sucrose gradient. Eggs from the least dense band (1.13 g/cm3) hatched within 10-13 hr when resuspended in a liquid medium and yielded a synchronous culture. The hatchability of these eggs ranged from 20-35%. Inhibitory effects of 5-fluorodeoxyuridine and hydroxyurea on freshly hatched (L1 stage) worms are described. Levels of isocitrate lyase were determined in eggs and in synchronous cultures. For biochemical and nutritional research on free-living nematodes axenic cul-tures are highly desirable. Several free-living nematodes feed on bacteria, fungal mycelia, yeast or algae. In their natural habitat these nematodes are usually con-taminated with more than one soil microorganism. Dougherty & Calhoun (1948) first reported axenic cultures of Rhabditi.r pellio and Caenorhabditis brigg.rae