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Control and virus‐transformed baby hamster kidney cells resistant to ethidium bromide. I. Characterization and the respiratory enzymes
Author(s) -
Soslau Gerald,
Zavodny Paul J.
Publication year - 1980
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041040203
Subject(s) - ethidium bromide , microbiology and biotechnology , biology , baby hamster kidney cell , cell culture , biochemistry , cell , dna , genetics
Cell lines resistant to ethidium bromide have been developed from cultured mammalian BHK 21 /C 13 cells and these same cells transformed by Rous sarcoma virus (C 13 /B 4 ). Cells resistant to 2 μg ethidium bromide per milliliter have been cloned. One clone of the control and one of the virus‐transformed cell lines has been employed for characterization. The resistant cells, in the presence of 2 μg ethidium bromide/ml, grow at approximately the same rate as the untreated parental cells. The control cells possess a “normal” karyotype (44 chromosomes), while the corresponding ethidium bromide mutant has a reduced chromsome number of 41 and a number of translocations. The mitochondria displayed morphological alterations compared to the parental lines during the transition phase prior to the isolation of the ethidium bromide‐resistant cells. The mitochondria of the ethidium bromide‐resistant mutants appear somewhat enlarged with a normal morphology. The effect of ethidium bromide on selected respiratory enzymes in normal and virus‐transformed ethidium bromide‐resistant baby hamster kidney cells was determined. Ethidium bromide‐resistant cells exhibited a depressed level of cytochrome aa 3 . This depression could not be reversed by growth in ethidium bromide‐free media. Ethidium bromide‐resistant cells possessed the same cytochrome b, c, and c 1 levels per cell as their corresponding parental lines. Purified mitochondria isolated from virus‐transformed ethidium bromide‐resistant cells exhibited a depression in cytochrome oxidase‐specific activity, while the ethidium bromide‐resistant control cells did not. All cell lines studied showed a depression in NADH‐ferricyanide and NADH‐cytochrome c reductase‐specific activities relative to parental BHK 21 /C 13 cells. An increase in succinate dehydrogenase and succinate cytochrome c reductase‐specific activities was observed in ethidium bromide‐resistant control cells relative to their parental BHK 21 /C 13 cells. No increase was observed in virus‐transformed ethidium bromide‐resistant cells. Ethidium bromide‐resistant control cells exhibited a two‐fold increase in oligomycin‐insensitive adenosine triphosphatase activity relative to their parental cells. All of the cell lines studied possessed equivalent oligomycin‐sensitive adenosine triphosphatase‐specific activity except for the virus‐transformed, dyeresistant mutant, whose activity was increased.