SPECIFICITY OF THE TEST BASED ON MODIFICATION OF CELL MORPHOLOGY FOR DETECTION OF LIPOPHILIC INHIBITORS OF PROTEIN PHOSPHATASES

The test based on morphological changes in KB cells was assayed with d ifferent toxins. Only lipophilic inhibitors of protein phosphatases, s uch as okadaic acid or calyculin A, induced visible changes in cell mo rphology. The activity of contaminated mussel extracts on KB cells was evaluated comparatively by direct interpretation of morphological cha nges and by a colorimetric method estimating the number of viable cell s after staining. The latter technique revealed interferences (not det ected by the former) with mussel cytotoxins. These results show that t he technique, based on determination of the minimal active concentrati on of toxic extracts inducing morphological changes, is more specific, faster and preferable to the determination of IC50, for the detection of protein phosphatase inhibitors in shellfish. (C) 1997 Elsevier Sci ence Ltd.