Submitted to: Mammalian Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 30, 2000
Publication Date: August 1, 2000
Citation: Sonstegard, T.S., Garrett, W.M., Ashwell, M.S., Bennett, G.L., Kappes, S.M., Van Tassell, C.P. 2000. Comparative map alignment of bta27 and hsa4 and 8 to identify conserved segments of genome containing fat deposition qtl. Mammalian Genome. 11(8):682-688. Interpretive Summary: Fat deposition is an economically important trait in cattle. Fat deposition ultimately determines carcass yield grade and quality in beef cattle, and in dairy cattle fat stores serve as energy reserves for lactation. Phenotypic differences in these traits affect profit margin for both cattle industries. Trait loci for fat deposition have been identified on bovine Chromosome 27 in two different cattle breeds, one dairy and the other beef We applied human comparative mapping information to the bovine map in order to identify a region of human Chromsome 8p (short arm) that corresponds to the estimated location of these fat-related traits, and use this information to refine the genetic interval on the cattle linkage map. Large genomic clones containing bovine homologues of 12 genes located on human Chr 4 (HSA4) and 8 were isolated and mapped. Polymorphic markers developed from these clones were ordered on the linkage map to more accurately determine the location and orientation of HSA8p conserved segments on the BTA27 comparative map. Our results indicate that BTA27 contains at least three conserved segments of HSA4q and HSA8p. This analysis suggests the segment of human genome containing the gene FNTA corresponds to the region of BTA27 presumed to contain fat-related traits. Overall, our data reveals a complex rearrangement of gene order between bovine and human chromosomes that underscores the potential difficulty of applying comparative mapping information to identify genes underlying quantitative trait loci (QTL).
Technical Abstract: Quantitative trait loci (QTL) associated with fat deposition have been identified on bovine Chromosome 27 (BTA27) in two different cattle populations. To generate more informative markers for verification and refinement of these QTL containing intervals, we initiated construction of a BTA27 comparative map. Fourteen genes were selected for mapping based on previously identified regions of conservation between the cattle and human genomes. Markers were developed from the bovine orthologues of genes found on human Chromosome 1 (HSA1), 4, 8, and 14. Twelve genes were mapped on the bovine linkage map using markers associated with single nucleotide polymorphisms or microsatellites. Seven of these genes were also anchored to the physical map by assignment of fluorescence in situ hybridization probes. The remaining two genes not associated with an identifiable polymorphism were assigned only to the physical map. In all, seven genes were mapped to BTA27. Map information generated from the other seven genes not syntenic with BTA27 refined the breakpoint locations of conserved segments between species and revealed three areas of disagreement in the previous comparative map. Consequently, portions of HSA1 and 14 are not conserved on BTA27, and a previously undefined conserved segment corresponding to HSA8p22 was identified near the pericentromeric region of BTA8. These results show that BTA27 contains two conserved segments corresponding to HSA8p, which are separated by a segment corresponding to HSA4q. Comparative map alignment strongly suggests the conserved segment paralogous to HSA8p21-q11 contains QTL for fat deposition in cattle.