Figure 2

FISH to pachytene chromosomes of turkey and chicken illustrating the MGA2/GGA3 inversions. Co-hybridization with CHORI-260 107N20 (red, WUGSC2.1/galGal3 BES coordinates 128288-325088) and 090K24 (green, 2711577-2958331) to turkey pachytene chromosomes gives overlapping signals (A) displayed by color-coded arrowheads, whereas with chicken pachytene chromosomes (B), 107N20 is telomere-adjacent and separated from 090K24 by about 2.5 Mb, as would be expected from the chicken sequence BES alignments. This is consistent with the p-arm inversion on MGA2 relative to GGA3 (Figure 1). Additional FISH with the TM1 centromere probe (unpublished observation) confirms that the MGA2 centromere is telomere-adjacent. Co-hybridization with CHORI-260 095D05 (red, WUGSC2.1/galGal3 BES coordinates 5361781-5538321) and 110E18 (green, 5654670-13311876) to turkey pachytene chromosomes (C) gives distinct, well-separated signals, whereas with chicken pachytene chromosomes (D), the 110E18 signal (green arrowheads) is split, as expected from its inconsistently spaced BES alignment, with one signal adjacent to the 095D05 hybridization (red arrowhead) and the other signal internal on MGA2. The p-arm of MGA2 (A, C) and GGA3 (B, D) is oriented toward the top of each image. These results support inversion of the turkey segment orthologous to the 5.6-11.6 Mb portion of GGA3, as shown in Figure 1. The chicken sequence coordinates of the BACs used as probes are indicated alongside the GGA3 bivalents shown in B and D. Scale bar = 1 μm.