Analisi ultrastrutturale degli effetti della monensina in Euglena gracilis,con particolare riguardo all'apparato di Golgi

Abstract

Ultrastructural analysis of the effects of monensin in Euglena gracilis, with special reference to the Golgi apparatus. - The monovalent ionophore, monensin, is known to affect the mature (trans) half of the dictyosomes of several organisms, including Euglena gracilis. We demonstrated that the exposure to high concentrations of this compound (2.5 × 10^?5 to 10^?4M) provoked remarkable swelling also in the forming (cis) half of Euglena cisternae. Additional dilations affected the thylakoids of both mature chloroplasts and proplastids of greening cells in which the organelle development was slower than in the control group. No osmotic swelling was observed for the mitochondria. Since monnesin exchanges one proton for each monovalent cation (Na⁺ or K⁺) transported, it follows that an energy driven influx of H⁺ is necessary to accumulate sufficient osmotically active ions in a membrane compartment. Thus it is possible that H⁺-ATPases are present on both forming and mature half of Euglena dictyosomes.