Worm Breeder's Gazette 8(2): 13
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
Using phosphorus nuclear magnetic resonance (NMR), the major phosphorus-containing metabolites of C. elegans have been detected in perchloric acid extracts. A new unidentified compound giving a major resonance in the phosphodiester region of the spectrum was detected. This resonance does not correspond to phosphocreatine, phosphoarginine or several other common phosphodiesters tested. The relative concentrations of metabolites change during the life cycle, producing distinct NMR spectra which correlate with differences in the metabolic pathway being preferentially utilized by the nematode. During the L1 stage, NMR spectra showed low concentrations of ATP, ADP, and inorganic phosphate relative to the other peaks present. These metabolite concentrations are probably associated with high activity of the glyoxylate metabolic pathway known to be present in C. elegans. Through the L2, L3 and L4 larval stages, NMR spectra reflect much higher concentrations of ADP, ATP, and the unknown phosphodiester. This most likely indicates increased respiration via the TCA cycle. Finally, the predominant signal in dauer larvae (as well as in starved L2 and L3 larvae) corresponds to inorganic phosphate. This low energy state in dauers returned to the higher energy state characteristic growing L2, L3, and L4 larvae within 4 hours after the dauer larvae resumed feeding in the presence of bacteria. Energy metabolism in C. elegans is, therefore, highly variable with switches between metabolic states readily occurring. The ability to utilize different metabolic strategies was further studied by the use of dauer-constitutive mutations in the genes daf-7 and daf-2. These temperature-sensitive mutants form dauer larvae at 25 C regardless of other environmental cues, thereby allowing dauer formation to be studied under the same environmental conditions as non- dauer larva development. Pre-dauer L2 larvae (L2d) did not show the high energy metabolism of pre-L3 L2 larvae but instead showed spectra corresponding to that of L1 larvae. This may indicate that the glyoxylate pathway was being utilized and the TCA pathway did not predominate during dauer larva formation. We conclude from these results that C. elegans metabolism responds to environmental change, but is also developmentally regulated. Isolation and identification of the unknown phosphodiester and a study of glyoxylate-specific and TCA-specific enzyme activities during larval development are currently in progress. [See Figure 1]