Abstract

Terramycin, in various concentrations, was added to culture media in which HeLa cells were proliferating. Bright-field and fluorescent microscopy revealed that terramycin is rapidly and specifically bound to the mitochondria. At low concentrations no changes in mitochondrial morphology were apparent. When concentrations were increased to 100 µg/ml or higher, the mitochondria became distended and rounded up. Marked alterations in mitochondrial structure were observed at concentrations of 100 µg/ml with the electron microscope. These changes included vacuolation, compression of the cristae, and striking reduplication of the mitochondrial membranes. At 300 µg/ml no normal mitochondria were present, and degeneration of other cytoplasmic elements occurred. Concentrations of 1000 µg/ml proved lethal for all cells. * Supported by grant #527 from the Damon Runyon Fund for Cancer Research. Present address: St. Jude Hospital, Memphis, Tennessee.