Fig. 7. Typical ¹³C NMR spectrum of perchloric acid extracts of haemolymph from fifth-instar M. sexta larvae given a dietary choice for 48 h and administered [2-¹³C]pyruvate. (A) Spectrum in the region –5.0 p.p.m. to 210 p.p.m. showing enrichments for alanine, trehalose and C5 of glutamate and glutamine. (B) Partial spectrum in the region 14–96 p.p.m. showing ¹³C-enrichments for C2 and C3 of alanine and Gl_x. (C) Partial spectrum in the region 59–96 p.p.m. showing the selective ¹³C-enrichment in trehalose, as well as other metabolites, including glycerol and glycerol phosphate with the same or similar chemical shifts. Haemolymph was collected 3.5 h post-injection. The spectrum was generated from 4000 data acquisitions and is shown with 3 Hz line broadening. See text for explanation of the metabolic derivation of ¹³C-enrichments.