Metabolic responses to anabiosis in the fourth stage juveniles of Ditylenchus dipsaci (Nematoda)

Abstract

The fourth stage juveniles of the stem nematode Ditylenchus dipsaci can lose almost all of their body water and survive in an anabiotic state for long periods of time. Desiccation of the juveniles does not seem to result in any appreciable denaturation of the metabolic enzymes. Comparison of the metabolite profiles of active and anabiotic juveniles shows a decrease in the content of the glycolytic intermediates in the anabiotic stages, but little change in the tricarboxylic acid cycle intermediates. The adenylate charge is greatly reduced in the anabiotic state, but ATP is still present in measurable amounts. The dry anabiotic juveniles of D. dipsaci are permeable to water and hydrate rapidly, although there is a lag phase of 2-3 h after hydration before spontaneous activity starts. Metabolism, as judged by heat output, oxygen uptake or 14 CO 2 production from labelled substrate begins immediately after hydration. The metab­olite levels also recover quickly; the ATP levels, however, do not return to normal for several hours and there is evidence that for some time after hydration the mitochondria are essentially uncoupled. During the dehydration-hydration cycle of the juveniles, membrane function is disrupted and the lag phase following hydration may result from the time required for the re-establishment of ionic and metabolic gradients within the tissues.