Folate-sensitive and aphidicolin-inducible fragile sites are expressed in the genome of the domestic cat.

Peripheral blood lymphocytes from three clinically normal domestic cats were cultured for folate-sensitive and aphidicolin-inducible fragile site expression. Induction of folate-sensitive fragile sites was accomplished by culturing cells with trimethoprim plus caffeine. Chromosomes from all cats expressed both folate-sensitive and aphidicolin-inducible breaks and gaps. There were no significant differences between the two methods of fragile site induction in the percentage of cells expressing chromosome breaks and gaps or the mean number of breaks and gaps per cell. All three cats expressed specific chromosome breaks resembling fragile sites at A1q21-22, A1p22, and B1q32. All three sites were induced by aphidicolin. The sites at A1q21-22 and B1q32 were also induced in folate-deficient medium. This is the first report of the induction of chromosomal fragile sites in a feline species.