Amino acid synthesis in Neomysis integer and gnathophausia sp.F̄eeding experiments using 14C-labelled precursors

Abstract

1. 1. Taurine, glycine, aspartate, threonine, glutamate, proline arginine, tyrosine, lysine, phenylalanine, isoleucine, leucine and valine appear to be non-essential to Neomysis integer. Synthesis of alanine, serine, cysteic acid and ornithine also occurred. 2. 2. Substantially greater incorporation of isotope into free and protein amino acids occurred from the starch-based diet than from the protein-based diet, in N. integer. 3. 3. Frequency of labelling suggests that glycine is of considerable importance to N. integer. 4. 4. Taurine, glutamate, alanine, valine, proline, aspartate and phenylalanine appear to be non-essential to Gnathophausia. Synthesis of serine and cysteic acid also occurred. 5. 5. Gnathophausia appears to place less reliance on protein as a metabolic substrate than does N. integer—lipid may be more important. 6. 6. Amino acids appear not to be significant precursors of chitin synthesis in Gnathophausia; this may represent one of the major routes of glucose metabolism in this species. 7. 7. Frequency of labelling suggests that alanine may be of particular importance to Gnathophausia. 8. 8. Several of the amino acids previously identified by injection techniques, as essential amino acids to Crustacea appear not to be essential to N. integer. This is thought to indicate the normal contribution of the gut micro-organisms to crustacean metabolism. 9. 9. It is suggested that further development of labelled feeding techniques to give a greater uptake of isotope would enable a more realistic identification of those acids required by crustaceans in their diet.