Carotenes from Mutants of the Dinoflagellate, Crypthecodinium cohnii |
| |
Authors: | NANCY W. WITHERS ROBERT C. TUTTLE |
| |
Affiliation: | Scripps Institution of Oceanography and Department of Biology, University of California, San Diego, La Jolla, California 92093 |
| |
Abstract: | SYNOPSIS. The carotenoid compositions of 15 nitrosoguanidine-induced mutants of Crypthecodinium cohnii , a heterotrophic dinoflagellate, were determined by chromatographic and mass spectral analyses. Wild-type C. cohnii grown with irradiation of 250 W/cm2 visible light at 27 C synthesizes β-carotene (33%) and γ-carotene (67%) amounting to 0.083 mg/g dry wt. There are 4 types of carotenoid-deficient mutants: (I) albinos which synthesize no C40-carotonoids: (II) albinos blocked at the level of phytoene desaturation; (III) cream-colored cells which accumulate mainly §–carotene, with phytoene and/or β-zeacarotene also present; and (IV) light-orange strains which synthesize reduced amounts of β-carotene and γ-carotene. Dark-grown wild-type cells produced 35% as much carotenoids as light-grown cells. Inhibition studies revealed that diphenylamine (3 γ) caused phytoene accumulation; nicotine at 0.9 mM blocked the final cyclization, to cause γ-carotene to accumulate in wild-type cells. Inhibition by adenine and guanine (1.5 mM) of carotenogenesis was demonstrated for the first time in any system. The effect of these purines was similar to that of diphenylamine addition: phytoene desaturation was largely inhibited. The carotenogenic system in this dinoflagellate is similar to that of green algae and higher plants, and is under nuclear genetic control. |
| |
Keywords: | Index Key Words: Crypthecodinium cohnii dinoflagellate carotenoid mutants phytoene ˜–carotene carotenogenic inhibition. |
|
|