OCCURRENCE OF FREE D-AMINO ACIDS IN THE GAMETES, EMBRYOS, LARVAE AND ADULTS OF THE SEA-SQUIRT CIONA-INTESTINALIS

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. In eggs we found 0.114-mu-mol/g wet weight of D-Asp plus D-Glu (0.644 pmol/cell) and 0.125-mu-mol/g wet weight of other D-amino acids (0.694 pmol/cell). 3. Spermatozoa contained 0.114-mu-mol/g wet weight of D-Asp plus D-Glu (2.6 . 10(-6) pmol/cell) and 0. 132-mu-mol/g wet weight of D-amino acids (3.0 . 10(-6) pmol/cell). 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. The occurrence of D-amino acids in Tunicata suggests that they play a specific role in the early stages of development.