Effects of DDT and Polychlorinated Biphenyls on Cellular Metabolism and Ultrastructure of 'Crithidia Fasciculata', a Flagellated Protozoan.

摘要

DDT and polychlorinated biphenyls (PCBs) have been shown to be toxic to Crithidia fasciculata by inhibition of cell population growth. Energy metabolism, protein and nucleic acid biosynthesis, and ultrastructure were chosen as indices for determining the metabolic site(s) of this inhibition. DDT had no effect on carbon dioxide evolution, whereas PCB exposure caused a transient inhibition and then stimulation after 6 and 24 hours, respectively. After 6 hours exposure to DDT or PCB, inhibition of both uptake and incorporation of thymidine and uridine, but not of L-leucine, was observed. By 24 hours of PCB exposure, uptake and incorporation of these three radioprecursors were two to three times greater than control. After 24 hours DDT exposure, only thymidine uptake and incorporation exhibited such an increase. Ultrastructural changes induced by these compounds included cellular and mitochondrial swelling, disruption of the mitochondrial genophore, and failure of the mitochondrion to replicate in synchrony with cell division.