EFFECTS OF DESTRUXINS, CYCLIC DEPSIPEPTIDE MYCOTOXINS, ON CALCIUM BALANCE AND PHOSPHORYLATION OF INTRACELLULAR PROTEINS IN LEPIDOPTERAN CELL-LINES

The influence of the destruxin E, cyclodepsipeptidic mycotoxin produce d by the filamentous entomopathogenic fungus Metarhizium anisopliae,on calcium fluxes and protein phosphorylation of in vivo cultivated lepi dopteran cell lines have been studied. The use of the fluorescent calc ium indicator Fura 2 AM did not show a fast increase in the level of c ytosolic calcium in lepidopteran and human cell lines treated with dtx E. In contrast, Ca-45(++) assays detected a late but significant calc ium influx in insect cells exposed to dtx E and A for at least 30 min. This effect was not inhibited by calcium channel blockers with the ex ception of nifedipine 25 mu M. A viral treatment potentiated the effec t of dtx E on calcium balance. Duc E also induced a strong, fast (10 m in), transient phosphorylation of high molecular weight (250 kDa) cell ular proteins. The activation of phosphorylation was only partially in hibited by EDTA. This study provides the first direct evidence of dtx E influence on calcium fluxes and protein phosphorylation.