ELECTROPHORETIC ANALYSIS OF POLYPEPTIDES OF PROROCENTRUM MICANS EHRENBERG EXPOSED TO TOXIC LEVELS OF COPPER

The effects of toxic levels of copper in the dinoflagellate Prorocentr um micans Ehrenberg were investigated by analysis of SDS-PAGE polypept ide profiles. Sublethal levels of copper added to exponentially growin g batch cultures induced evident alterations in the growth of the cult ures and in the soluble protein concentration per cell (51% reduction of the number of cells and 36% of the total soluble protein content, a fter 14 days of 3.94 mu M copper exposure). The highest copper concent ration (7.87 mu M) clearly inhibited the culture growth. The SDS-PAGE polypeptide profiles of control and 14 days copper treated cultures ex tracts, showed the presence of similar polypeptides between ca. 30 and 110 kDa, but the relative amounts of some of them was changed. Using as reference in each profile the most preeminent polypeptide (33.5 kDa ), a reduction of the amounts of the 35 and 39.5 kDa polypeptides and an increase of the 42, 46, 47.5 and 104 kDa ones were observed when co mpared to the control. The results indicate the occurrence of copper t oxicity at the protein level in P. micans, as well as interference in the growth of the cultures.