TOXIC ACTION OF COPPER ON THE MEMBRANE SYSTEM OF A MARINE DIATOM MEASURED BY FLOW-CYTOMETRY

Flow cytometric measurements were used to investigate the toxic action of copper on some Phaeodactylum tricornutum membrane systems. Through out the time of metal exposure, the percentage of viable cells decreas ed as copper concentration increased. The forward scatter signal incre ased as a result of copper exposure. After 72 h of metal exposure, cul tures with 0.5 and 1 mg l(-1) of copper showed an important increase i n the peroxidase activity in comparison with control cells. Cells cult ured with copper presented alterations in the membrane potential, Incr easing as copper concentration increased, after 96 h of metal exposure . Results obtained in this work showed that copper induced a degenerat ive process in P. h tricornutum cells, closely related with alteration s or disorders in membrane systems. (C) 1996 Wiley-Liss, Inc.