CAROTENOID PIGMENTS IN THE CELLULAR SLIME MOLD, DICTYOSTELIUM DISCOIDEUM ,

1. The lemon-yellow pigmentation in the mature sori of the cellular slime mold, Dictyostelium discoideum, was shown to arise by de novo synthesis and not by accumulation from an exogenous source. Pigment synthesis reached a peak after fruiting and then sharply declined in the vegetative phase.2. The major pigments appeared to be related to the zeta-carotenes. Inhibition of pigment synthesis by diphenylamine, which specifically inhibits carotenogenesis, indicated the pigments were carotenoids. Chemical and spectral analyses of the pigments indicated polyene structures with seven conjugated double bonds.3. Most of the pigments contained acidic functions. The acidic function of one pigment appeared to be conjugated with the chromophore.