Production of transmitochondrial mouse cell lines by cybrid rescue of rhodamine-6G pre-treated L-cells.

Treatment of mouse LMTK- cells with the toxic mitochondrial dye rhodamine 6G (R-6G) at 2.5 micrograms/ml for 7 days prevented cell growth while maintaining viability, with less than 10(-6) cells recovering to form colonies. Pre-treatment of LMTK- cells with R-6G was followed by fusion with enucleated mouse 501-1 cells harboring a homoplasmic point mutation in the mitochondrial DNA (mtDNA) 16S rRNA gene conferring chloramphenicol resistance (CAPR). Cybrids and any surviving unfused LMTK- cells were selected in BrdU with or without CAP and their mtDNAs screened for the presence of the CAPR marker. Approximately 1 colony per 2 x 10(5) LMTK- cells appeared in the fusion plates selected both with and without CAP. Most clones investigated were confirmed to be cybrids by showing the presence of the generally homoplasmic CAPR mutation, whether or not CAP selection was used. Hence, R-6G pre-treatment permits construction of transmitochondrial cybrid cell lines carrying a variety of mtDNAs, without the need for rho 0 cell lines.