Phospholipid changes in Rhinella arenarum embryos under different acclimation conditions to copper

Abstract

We report phospholipid changes in Rhinella arenarum embryos after applying three acclimation protocols to copper between 40 and 420 ng L- 1. The lower and higher acclimation treatments resulted in embryos' enhanced resistance to this metal. Phospholipid remodeling activity, evident through arachidonic acid radioactivity incorporation increase in phosphatidylcholine (PC) and sphingomyelin (SPH) fractions, was registered in embryos acclimated to the intermediate exposure condition. Concomitantly, a decrease in phosphatidic acid fraction (PA) was registered in the higher acclimation condition. PC/PE radioactivity ratio increased both for medium and high acclimation conditions from 0.493 in control embryos to 1.378 and 1.032 respectively. Phospholipid changes could be relevant for changes in membrane features associated with low level exposures to copper, preparing the embryo for a higher resistance to this metal. The increased resistance to copper could also be associated with both an increase in metallothioneins concentration, as registered with HPLC in all the acclimation conditions, and an increase in the copper bound to the third fraction of metallothioneins separated by this method. Our results point out that even very low level exposure to copper results in phospholipid metabolism changes that could be relevant for the acclimation phenomena.