Fig. 2.

¹H NMR spectral comparison of zebra mussel and SRM 1974c (M. edulis). Representative ¹H NMR spectra of zebra mussel from the reference site (bottom), and M. edulis SRM 1974c (top) are shown. a Upfield NMR spectrum (0.0–4.0 ppm), b downfield NMR spectrum (5.0–10.0 ppm). (1) Leu, Ile, Val; (2) lactate, Thr; (3) Ala; (4) Arg; (5) Lys; (6) putrescine*; (7) ornithine*; (8) methyl-4-aminobutyrate*; (9) UDP-N-acetylglucosamine*; (10) Met; (11) acetoacetate^†; (12) Glu; (13) succinate; (14) Gln; (15) β-Ala^†; (16) hypotaurine^†; (17) Asp; (18) trimethylamine*; (19) Asn; (20) l-methionine methylsulfonium iodide^†; (21) choline, phosphocholine, glycerophosphocholine; (22) betaine; (23) taurine^†; (24) Gly; (25) Ser; (26) homarine^†; (27) maltose; (28) glycogen; (29) uridine*; (30) adenosine; (31) Tyr; (32) His; (33) Phe; (34) Trp; (35) ATP/ADP; (36) AMP. The asterisks indicates metabolites identified only in zebra mussel and (dagger) only in M. edulis. The unidentified peaks which have correlated ¹³C chemical shifts are labeled with A–E. (A) 1.10 ppm^† (s); (B) 1.25 ppm* (s); (C) 3.12 ppm (s); (D) 3.15 ppm^† (s); (E) 3.48 ppm* (d or two s). The complete list of annotated metabolites and their ¹H and ¹³C chemical shifts are listed in Supplemental Tables 2 and 3