Occurrence of free d-amino acids in the gametes, embryos, larvae and adults of the sea-squirt Ciona intestinalis

Abstract

1. 1. In the present study we report the presence of d-amino acids in gametes, embryos at various stages of development and adults of the tunicate Ciona intestinalis. This report constitutes the first demonstration of the occurrence of d-amino acids in spermatozoa. 2. 2. In eggs we found 0.114 μmol/g wet weight of d-Asp plus d-Glu (0.644 pmol/cell) and 0.125 μmol/g wet weight of other d-amino acids (0.694 pmol/cell). 3. 3. Spermatozoa contained 0.114 μmol/g wet weight of d-Asp plus d-Glu (2.6·10 −6 pmol/cell) and 0.132 μmol/g wet weight of d-amino acids (3.0·10 −6 pmol/cell). 4. 4. In embryos, the concentration of these enantiomers decreases with the increase of the stages of development. In adults their level is about 10% of that in gametes. 5. 5. The occurrence of d-amino acids in Tunicata suggests that they play a specific role in the early stages of development.