Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 3, 2004
Publication Date: December 1, 2004
Citation: Kim, J.G., Rohrer, G.A., Vallet, J.L., Christenson, R.K., Nonneman, D. 2004. Addition of 14 anchored loci to the porcine chromosome 8 comparative map. Animal Genetics. 35(6):474-476. Interpretive Summary: Several regions on porcine chromosome number 8 are associated with differences in reproductive traits, including the number of ova shed per reproductive cycle, the ability of the uterus to accommodate fetuses to term, survival of pig fetuses to term and age of the pig at the start of reproductive cycles. Regions of this chromosome are similar to regions of human Chromosome number 4, thus comparisons to human chromosome 4 allows prediction of the different genes in specific regions of chromosome 8. However, the exact order of genes on swine chromosome 8 is not clear because of possible rearrangements in gene order compared to human chromosome 4. The purpose of this study was to find regions of gene rearrangement between swine chromosome 8 and human chromosome 4 by determining the order of 14 genes on swine chromosome 8 and comparing this with the known order of the same genes on human chromosome 4. Two reversals in gene order were obtained, a small one at the top of chromosome 8, and a larger one occurring in the last third of chromosome 8. Knowledge of these rearrangements of gene order improve the ability to predict the order of genes on swine chromosome 8 from the known gene order on human chromosome 4, and thus allow a much better prediction of genes that could be responsible for the associations between regions of swine chromosome 8 with reproductive traits.
Technical Abstract: Several regions on porcine chromosome 8 have been identified that affect reproductive traits including ovulation rate, uterine capacity, prenatal survival and age of puberty. In order to identify the genes affecting these traits, efforts have been made to develop comparative maps with human and pigs. Porcine chromosome 8 is homologous to human chromosome 4, but a significant number of rearrangements in gene order exist. The purpose of this study was to place additional anchored markers on the genetic linkage map specifically in QTL regions for uterine capacity and ovulation rate. These are regions where gene order differs compared to human and an attempt was made to narrow the locations of these rearrangements. Fourteen genes located on human chromosome 4 were mapped by linkage or the IMpRH radiation panel to pig chromosome 8. One small rearrangement was observed between 3-8.5 Mb on the human map, corresponding to about 2-16 cM on the porcine map, in a region that contains a QTL for ovulation rate. Another inversion of gene order was defined between 80-150 Mb of human chromosome 4, which corresponds to 70 cM to the end of the linkage group on pig chromosome 8. The addition of these markers to the comparative map will help identify positional candidate genes for economically important traits.