Localization of fragile sites in the karyotype of Felis catus

High resolution RBG-banding was induced by exposure of cat fibroblast cultures to a folate antagonist and BUdR. After band induction the chromosomes displayed frequent breaks and gaps. To determine whether the observed aberrations were randomly or non-randomly distributed, a total of 300 metaphases were screened for the presence of breaks, gaps, and deletions. Statistical analysis was performed according to Mariani (1989). The 525 band idiogram presented by Rønne et al. (1994) was used for the calculations, and to determine which bands were harbouring an aberration. Bands with seven or more aberrations were considered to harbour a fragile site (Fh7 < 0.01).