CHANGES IN SOME CHEMICAL-COMPONENTS OF ALEXANDRIUM-CATENELLA AND SCRIPPSIELLA-TROCHOIDEA DURING THEIR GROWTH CYCLES

Changes in some chemical components of Alexandrium catenella (Whedon e t Kofoid) Balech and Scrippsiella trochoidea (Stein) Loeblich III (Din ophyceae) during their growth cycles were examined. Results clearly sh owed that the cellular content of carbon and nitrogen gradually increa sed during lag and early exponential phases of growth. Thereafter, the y decreased and became nearly constant from mid exponential phase to t he end of the experiment. Changes in cellular phosphorus and cellular ATP content of these dinoflagellates showed the same general patterns as those of carbon and nitrogen. It was observed that after cellular c ontent of ATP remarkably increased and reached a maximum level, cell n umber increased rapidly. Glutamic acid, glycine, and alanine were the predominant components of amino acids in both dinoflagellates. The mea n values of nitrogen content in total amino acids in A. catenella and S. trochoidea throughout the growth cycle were higher than 40 and 60% of total cellular nitrogen, respectively. Since the changes in pattern of cellular amino acid content followed the same pattern as that of c ellular nitrogen, it could be concluded that cells accumulated nitroge n compounds mainly in the form of amino acids. Relative abundance of a rginine in S. trochoidea was nearly stable throughout the growth cycle , whereas, the relative abundance of arginine in A. catenella dramatic ally increased from the beginning of the stationary phase to the end o f the experimment. It could be suggested that changes in cellular amin o acid composition played an important role in the growth processes of this marine dinoflagellate.