Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học quốc tế đề tài: Mapping of a milk production quantitative trait locus to a Mb region on bovine chromosome 5 in the Fleckvieh dual purpose cattle breed | Awad et al. Genetics Selection Evolution 2011 43 8 http content 43 1 8 GSE Ge n et i cs Selection Evolution RESEARCH Open Access Mapping of a milk production quantitative trait locus to a Mb region on bovine chromosome 5 in the Fleckvieh dual purpose cattle breed 1 2 1 Ashraf Awad Ingolf Russ Martin Forster1 Ivica Medugorac Abstract Background In a previous study in the Fleckvieh dual purpose cattle breed we mapped a quantitative trait locus QTL affecting milk yield MY1 milk protein yield PY1 and milk fat yield FY1 during first lactation to the distal part of bovine chromosome 5 BTA5 but the confidence interval was too large for positional cloning of the causal gene. Our objective here was to refine the position of this QTL and to define the candidate region for high-throughput sequencing. Methods In addition to those previously studied new Fleckvieh families were genotyped in order to increase the number of recombination events. Twelve new microsatellites and 240 SNP markers covering the most likely QTL region on BTA5 were analysed. Based on haplotype analysis performed in this complex pedigree families segregating for the low frequency allele of this QTL minor allele were selected. Single- and multiple-QTL analyses using combined linkage and linkage disequilibrium methods were performed. Results Single nucleotide polymorphism haplotype analyses on representative family sires and their ancestors revealed that the haplotype carrying the minor QTL allele is rare and most probably originates from a unique ancestor in the mapping population. Analyses of different subsets of families created according to the results of haplotype analysis and availability of SNP and microsatellite data refined the previously detected QTL affecting MY1 and PY1 to a region ranging from Mb to Mb Mb on BTA5. However the possibility of a second QTL affecting only PY1 at Mb was not ruled out. Conclusion This study demonstrates that .
