Protein and amino acid composition from the mantle of juvenile Octopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile Octopus vulgaris (Cuvier, 1797) during fasting for 27days were determined. Average protein content of octopus mantle was of 711.19 +/- 46.80gkg(-1)DW, and it decreased with increasing fasting days. The non-essential amino acids content was higher (486.18 +/- 11.08gkg(-1) protein) than essential amino acids (425.82 +/- 9.15gkg(-1) protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20days) or poor nutrition of O. vulgaris. This study supports the idea of using mantle for metabolic needs of starved O. vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.