Comparative mapping of genes from human chromosome 12 by genetic linkage mapping in cattle

Loci from human chromosome 12 were mapped in cattle to compare the gene ord er between species. Polymorphisms were detected in cattle in six loci that had been mapped with high precision in humans. Four of these loci, LALBA, S LC2A3, SYT1, and TPI1, mapped to bovine chromosome 5, and one, PLA2G1B, map ped to bovine chromosome 17. The sixth locus, SLC2A3L, due to a fragment pr oduced by the SLC2A3 primers, maps to the telomeric region of BTA18. The di fferences in gene order between human chromosome 12 and cattle chromosome 5 , when these loci are added to others already mapped in cattle, show eviden ce of significant rearrangement in gene order requiring several evolutionar y events. There is also evidence in cattle chromosome 5 of the interspersal of material conserved on human chromosome 22 into the material conserved o n human chromosome 12, consistent with ZOOFISH analyses. This analysis indi cates that the larger block near the centromere is conserved on the long ar m of human chromosome 12 and the smaller block near the telomere is conserv ed as part of the short arm of human chromosome 12. The level of variation detected in the amplified cattle DNA was approximately 1 variant per 464 nu cleotides of haploid DNA using single-strand conformation polymorphism anal ysis. This corresponds to a per individual level of 1 variant per 1, 961 nu cleotides of haploid DNA. This confirms lower genetic variability in cattle compared to humans but indicates the potential for millions of single nucl eotide polymorphisms in cattle.