Effects of mitomycin C and colchicine on toxin production and cell cycle regulation in the dinoflagellate Alexandrium tamarense

Paralytic shellfish toxin (PST) production and cell proliferation in the dinoflagellate Alexandrium tamarense were investigated under the influence of two metabolic inhibitors (mitomycin C and colchicine) that have different mechanisms of action. Intracellular PST levels in cells treated with 2 mu M mitomycin C increased gradually, reaching a maximum of 176 fmol/cell (a 6-fold increase). High concentrations of colchicine prolonged G(1) phase in A. tamarense cells, even though colchicine arrests several other eukaryotic cell types in M phase. The cells in prolonged G(1) phase under the influence of colchicine were apparently unable to produce PST. Cell proliferation and toxin production recovered after removal of colchicine; in contrast, the effect of mitomycin C was irreversible. While the timing of toxin production within the cell cycle was not conclusively determined, A. tamarense cells in S phase were able to produce PST. (C) 2010 Elsevier B.V. All rights reserved.