Carbon assimilation by different developmental stages of Laminaria saccharina

Various stages of the life cycle of the marine brown alga Laminaria saccharina (L.) Lamour. (Laminariales, Phaeophyta) including male and female gametophytes, female gametes, zygotes and young sporophytes of different age were investigated for their potentials of carbon dioxide (¹⁴CO₂) fixation. Rates of photosynthesis attain the same order of magnitude in all stages. Photosynthetic ¹⁴CO₂-fixation is accompanied by a substantial light independent carbon assimilation. This is confirmed by rate determinations of the equivalent carboxylating enzymes present in the plants, ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39) and phosphoenolpyruvate carboxokinase (EC 4.1.1.32) as well as by chromatographic analyses of the appropriate [¹⁴C]-assimilate patterns.Abbreviations RuBP-C ribulose-1,5-bisphosphate carboxylase - PEP-CK phosphoenolpyruvate carboxykinase - PEP phosphoenolpyruvate - PS photosynthesis - DF dark fixation