Effect of Chloramphenicol on the Ultrastructure of Mitochondria in Sensitive and Resistant Strains of Hela

Ethidium bromide and chloramphenicol (CAP) are known to impair mitochondrial nucleic acid and protein synthesizing ability . These compounds also bring about alterations in the mitochondrial ultrastructure (2-9, 11) . Correlation of ultrastructure with biochemical changes has been shown in both eukaryotic and prokaryotic cells grown in the presence of these inhibitors (1-9) . Ultrastructural changes in mitochondria of cultured human or mouse cells have been compared to their appearance under normal conditions of growth (2-4) . The isolation and characterization of clone 296-1, a CAP-resistant mutant of HeLa S3 cells, and the study of its mitochondrial protein synthesizing ability in vitro (10), prompted us to survey its ultrastructure in the presence and absence of CAP, and to compare it to S3 cells under the same conditions . This report indicates that, in the absence of CAP, the mitochondrial morphology of this mutant is similar to that of the parental S3 cells . Although the growth rate of the mutant remains unaltered after the addition of CAP, changes occur in the mitochondrial ultrastructure, but to a much lesser extent than in sensitive cells of the parent HeLa strain . After this work was completed, similar results were reported for a mutant of Paramecium resistant to CAP (11) .