Effect of 5-fluoro-2′-deoxyuridine on toxin production and cell cycle regulation in marine dinoflagellate, Alexandrium tamarense

• The effect of FUdR on toxin production of Alexandrium tamarense was examined.
• FUdR at 3–300 μM inhibited the cell proliferation and toxin production.
• FUdR at 203 μM resulted in cell cycle arrest at the S phase at day 4.
• Toxigenesis was inhibited after day 2 without significant changes in toxin profile.
• FUdR was suggested to inhibit biosynthesis in the early stage of the pathway.

The effect of metabolic inhibitor, 5-fluoro-2′-deoxyuridine (FUdR) on toxin production and the cell cycle of marine dinoflagellate, Alexandrium tamarense, was investigated. Compared to untreated cells, FUdR at 3 μM (p < 0.05) to 300 μM (p < 0.01) inhibited the cell proliferation and toxin production in a dose-dependent manner for A. tamarense cultured in modified T1 medium. FUdR at 203 μM resulted in cell cycle arrest at the S phase at day 4 and toxigenesis was inhibited after day 2. The toxin profiles of the FUdR-treated cultures were similar to those of the control culture. These results suggest that FUdR inhibits saxitoxin (STX) biosynthesis in the early stage of the pathway. This report is the first to demonstrate the inhibition of toxin production in A. tamarense by a nucleoside analog.