EFFECT OF DIETARY D-AMINO ACIDS ON GROWTH, SURVIVAL, AMMONIA EXCRETION AND SPECIFIC DYNAMIC ACTION IN THE SUPRALITTORAL ISOPOD, LIGIA-PALLASII

1. Growth, survival, ammonia excretion and Specific Dynamic Action (SDA) were assessed in the supralittoral isopod Ligia pallasii eating chemical diets with differing proportions of D- and L-amino acids. Growth and survival decreased in direct proportion to increasing dietary intake of D-amino acids. 2. Survival on diets with greater than 50% content Of D-amino acids (based on total amino acids in diet) was lower than that expected based on previous work, suggesting a deleterious effect of the D-isomers. 3. Ammonia excretion and SDA correlated negatively with increasing dietary content of D-amino acids. 4. The general conclusion is that D-amino acids play no role in anabolic or energy metabolism in Ligia, and that poor performance at higher dietary levels of D-amino acids may relate to their interference with transport pathways for the normal L-forms.