Temperature-induced phase transitions in nematode lipids and their influence on respiration.

Temperature-induced phase transitions estimated by electron spin resonance (ESR) technique were ohscrved in the lipids of several nematode species. In both Meloidogyne javanica and Caenorhahditis elegans, there was a phase transition in their phospholipids from a liquid-crystalline state to a solid gel state at about 10 C. Aphelenchus avenae also had a phase transition, but at about 20 C. With this species, the spin-label motion parameters indicated the transition was from the liquid-crystalline state below 20 C to a more liquid or disordered state above 20 C. Anguina tritici and Meloidogyne hapla, in contrast, had no phase transitions over the entire temperature range studied. Each phase transition detected by ESR was reflected in the respiratory rates of the nematodes, and the temperature of the transition coincides with the environmental adaptation of these species.