Accurate characterization of porcine bivariate flow karyotype by PCR and fluorescence in situ hybridization.

The 19 chromosomal pairs of the swine karyotype are resolved into 18 peaks denoted A to Q and Y by dual-beam flow cytometry. The chromosomal content of six peaks has previously been determined by analyzing male/female differences, karyotypes of animals carrying translocations, and PCR studies of genes with known assignments. For the remaining chromosomes, putative assignments to flow peaks were deduced from comparison of DNA contents, determined by flow cytometry, and chromosomal size. We present here the complete characterization of the pig bivariate flow karyotype using the PARM-PCR technique combined with fluorescence in situ hybridization. Chromosome-specific probes were generated by PCR amplification of 300 sorted chromosomes with primers under nonspecific conditions and used to paint chromosomes by FISH. The chromosomal content of each peak was identified: peaks A (chromosome 1), B (13), C (6), D (2), E (14), F (3), G (7), H (9,4,X), H1 (9), I (15), J (8), K (5), L (10), M (12), N (16), O (11), P (17), Q (18), Y (Y). We were able to characterize perfectly the pig bivariate flow karyotype. Such techniques could be applied to any other species.