MC2/3 is a mouse chromosome 8 specific monochromosome hybrid cell line. This hybrid resulted from the fusion of adenine phosphoribosyl transferase negative (APRT -) Chinese hamster ovary cells with micronuclei from near euploid thymidine kinase negative (TK -) CAK mouse cells. Hybrids containing mouse chromosome 8 (which has the APRT locus) were selected in medium containing 0.075 mM adenine, 800 nM aminopterin and 0.016 mM thymidine (AAT). The mouse chromosome 8 could be from either the C57BL/6J or ARK/J inbred strain, since CAK cells were derived from an F1 hybrid of those two strains. Mouse chromosome 8 may be isolated with 96% purity. The depositor has reported the presence of one copy of mouse chromosome 8 in each Chinese hamster cell by G band cytogenetics, fluorescence in situ hybridization (FISH) and PCR analysis. However, FISH analysis of ATCC frozen stocks by the depositor using biotinylated total genomic mouse DNA as probe indicates that 7 of 9 metaphases examined had a single mouse acrocentric chromosome present in a hamster background. Two of nine metaphases showed different rearrangements of the mouse acrocentric. An examination of interphase nuclei indicates that about 18% of the cells are tetraploid showing two distinct hybridization signals from the mouse while 82% are near diploid exhibiting one distinct signal. The level of tetraploidy may increase with additional passage. |
