Folate sensitive common fragile sites in chromosomes of the domestic pig (Sus scrofa).

Chromosomal fragile sites were studied in blood lymphocytes of the pig after induction with 0, 5, 10 and 20 micrograms of fluorodeoxyuridine (FudR) ml-1 of culture. The percentage of cells showing fragile sites and total breaks and gaps in 100 cells was significantly higher in all treated cultures than the control (P < 0.001). A concentration of 5 to 10 micrograms of FudR ml-1 of medium is recommended as the optimum for mitotic index and fragile site expression in the pig. Localisation of the fragile sites was by GTG banding after destaining of the conventionally stained Giemsa preparations. Common fragile sites in the pig were identified in 24 sites on 10 chromosomes. Some fragile sites corresponded to the breakpoints in known reciprocal translocations.