INTRACELLULAR STRUCTURES OF NORMAL AND ABERRANT PLASMODIUM-FALCIPARUMMALARIA PARASITES IMAGED BY SOFT-X-RAY MICROSCOPY

Soft x-ray microscopy is a novel approach for investigation of intrace llular organisms and subcellular structures with high spatial resoluti on, We used x-ray microscopy to investigate structural development of Plasmodium falciparum malaria parasites in normal and genetically abno rmal erythrocytes and in infected erythrocytes treated with cysteine p rotease inhibitors, Investigations in normal red blood cells enabled u s to recognize anomalies in parasite structures resulting from growth under unfavorable conditions, X-ray microscopy facilitated detection o f newly elaborated structures in the cytosol of fixed, unstained, inta ct erythrocytes, redistribution of mass (carbon) in infected erythrocy tes, and aberrant parasite morphology, In cysteine protease inhibitor- treated, infected erythrocytes, high concentrations of material were d etected in abnormal digestive vacuoles and aggregated at the parasite plasma membrane, We have demonstrated that an abnormal host erythrocyt e skeleton affects structural development of parasites and that this a berrant development can be detected in the following generation when p arasites from protein 4.1-deficient red blood cells infect normal eryt hrocytes, This work extends our current understanding of the relations hip between the host erythrocyte membrane and the intraerythrocytic ma laria parasite by demonstrating for the first time that constituents o f the erythrocyte membrane play a role in normal parasite structural d evelopment.