Comparative studies of the actin cytoskeleton response to maitotoxin and okadaic acid.
The specific cytotoxic effects of phycotoxins on BHK 21 C13 fibroblasts in culture were studied with maitotoxin (MTX), okadaic acid (OA) and crude extracts from Gambierdiscus toxicus Adachi and Fukuyo and Prorocentrum lima Ehrenberg. These dinoflagellates produce MTX and OA respectively. MTX and G. toxicus crude extracts caused large blebs within minutes after exposure, in a dose-dependent manner. F-actin fibres decreased in number, then disappeared. An increase in fluorescence was observed at the periphery of the nucleus. For one strain of G. toxicus F-actin granules were also observed. Cells exposed to OA or P. lima crude extracts became polygonal in shape and then round. At low doses this effect occurred only after a 24-hr exposure. F-actin fibres crossing the cytoplasm were reduced in size and number then disappeared, while peripheral F-actin fibres became shorter giving the cell first a polygonal and then a round shape. According to these specific responses we have defined an MTX-like effect which is distinct from an OA-like effect. In both cases the amount of F-actin diminished at doses that did not affect cell viability.
Diogène
G
G
Unité INSERM 303, 1 Avenue Jean Lorrain, F-06300, France.
Fessard
V
V
Dubreuil
A
A
Puiseux-Dao
S
S