FREE L-AMINO-ACIDS AND D-ASPARTATE CONTENT IN THE NERVOUS-SYSTEM OF CEPHALOPODA - A COMPARATIVE-STUDY

We have determined the content of free L-amino acids and D-aspartate i n the nervous tissue of three representative cephalopods: Sepia offici nalis, Octopus vulgaris, and Loligo vulgaris, and the optic lobes of a dult and embryo Sepia ofJicinalis. Taurine is the most abundant amino acid in the cephalopod nervous tissue. Its content amounts to more tha n 50% of the total free amino acids. The other most concentrated amino acids are Glu, Ala, Asp, and GABA. High concentrations of D-aspartate were found in the nervous tissue of all cephalopods examined (7-12 mu mol/g wet tissue) which represents 50-80% of the total aspartate (D L), depending on the animal. Among the various regions of the brain o f Octopus vulgaris, D-aspartate was found to be evenly distributed in the various regions of the brain. In nerve tissue of Sepia officinalis , there is no significant difference in the pattern of free L-amino ac ids, in particular of the D-aspartate concentration, between adults an d embryos, except for GABA, Gly, His and Thr. This suggests that D-asp artate in nerve tissue of the Cephalopoda is of endogenous origin and not a product of accumulation from exogenous sources. From a comparati ve study of the content of D-aspartate in the nervous tissue of differ ent animals, we found that protostomia contain a significantly higher amount than deuterostomia. Thus, D-aspartate could be a criterion to d istinguish the protostomia phyla from the deuterostomia phyla.