Metabolism in the CrayfishAstacvs Astacus(L.): I – Biosynthesis of Amino Acids

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Abstract
The biosynthesis of amino acids in Astacus astacus (L.) has been investigated with the aid of acetate-l-14C and 14C-glucose (uniformly labelled). It is shown that the amino acids valine, leucine, isoleucine, threonine, lysine, histidine and phenylalanine are essential. On the other hand, glycine, alanine, serine, aspartic acid, glutamic acid, tyrosine, proline, hydroxyproline and probably also arginine, are non-essential. The biosynthesis of the greater part of the non-essential amino acids could be traced by way of labelling with 14C. Generally the biosynthesis agrees with the results known for Vertebrates and Invertebrates. Differences found in the rate of labelling with 14C of the amino acids alanine, aspartic acid and glutamic acid between animals from autumn and those from spring suggest that synthesis takes place when needed. Carbon-14, from glucose administration, is in a high degree incorporated into non-essential amino acids. For aspartic acid the way of labelling could not be explained by the known synthesis in Vertebrates. There must be another way of synthesis to explain these results.