| Abstract |
Ethidium bromide (EB) efficiently induces respiratory mutants in yeast. In
all studies reported, the effect of sublethal concentrations of EB in
mammalian cells was either reversible after omission of the drug or
resulted in cell death. We describe a cell line, F, derived from the SV40-
transformed hamster cell line F5-1, iwhich is completely resistant to EB
at a concentration of 2 mug/ml, as shown by its colony-forming ability. At
this concentration, cytochromes c and b are present in almost normal, or
only slightly diminished, amounts whereas cytochromes a + a3 show a
significant decrease. All cytochrome changes are reversible when EB is
discontinued. The biophysical properties of the mitochondrial DNA of the
resistant cell are characterized and compared to the parental cell line.
The mitochondria of the F cell have a normal ultrastructure, not distinct
from the parental F5-1 cell line. The induced resistance to EB has been
hereditarily transmitted to the progeny cells for 11 months. Possible
underlying mechanisms of the resistance to EB and the significance of the
establishment of this cell line are discussed.
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