Characterization of reciprocal translocations in pigs using dual-colour chromosome painting and primed in situ DNA labelling

We report the use of dual-colour chromosome painting to determine the exact nature of certain chromosome rearrangements observed in the pig (Sus scrof a domestica). The chromosomal abnormalities were detected by GTG- and RBG-b anding techniques. The initially proposed interpretations were: (1) rcp(6;1 3)(p1.5;q4.1); (2) rcp(11;16)(p1.4;q1.4); (3) rcp(6;16)(p1.1;q1.1); (4) rcp (13;17)(q4.1;q1.1); (5) rcp(6;1 4)(q2.7;q2.1); (6) rcp(3;5)(p1.3;q2.3); (7) rcp(2; 14)(q1.3;q2.7); (8) rcp(15;17)(q1.3;q2.1). Hybridizations were carr ied out with biotin- and digoxigenin-labelled probes obtained by priming au thorizing random mismatches polymerase chain reaction (PARM-PCR) amplificat ion of porcine flow-sorted chromosomes. In some cases, i.e. (1), (4), (5), (6), (7) and (8), the fluorescence in situ hybridization (FISH) results all owed confirmation of the interpretations proposed with classical cytogeneti c methods. Chromosome painting proved the reciprocity of the translocation in cases (1), (6) and (8), whereas modifications of the formula were propos ed far case (2). Primed in situ DNA labelling (PRINS) experiments have also been carried out in case (3) using a primer specific for the centromeres o f acrocentric chromosomes (first experiment) or a primer specific for the c entromeres of a subset of meta- and submetacentric chromosomes including ch romosome 6 (second experiment). It allowed us to demonstrate that the break points occurred in the centromeric region of chromosome 16 and in the p arm of chromosome 6, just above the centromere.