EFFECTS OF MITOTIC GROWTH-FACTORS ON GROWTH-RATES IN MARINE DINOFLAGELLATES

The effects of different growth factors and mitogens (platelet-derived growth factor, phorbol 12 monoacetate and fetal bovine serum) on dino flagellate proliferation were analysed in axenic clonal cultures of th e bloom-forming dinoflagellates Prorocentrum triestinum Schiller and A lexandrium tamarense (Lebour) Balech. Cell yield and acclimatized maxi mal growth rates of all clones tested increased significantly due to t he specific mitogenic effect of growth factors. This is thought to be due to the existence of a universal mechanism controlling the cell div ision cycle in all eukaryotic cells. Apparently dinoflagellates respon d to growth factors in a similar way as mammalian and yeast cells. Bec ause growth factors can increase growth rates, they could play a signi ficant role in the occurrence and proliferation of dinoflagellate bloo ms.