Edinburgh Research Explorer Detection of quantitative trait loci for backfat thickness and intramuscular fat content in pigs (Sus scrofa)
Edinburgh Research Explorer Detection of quantitative trait loci for backfat thickness and intramuscular fat content in pigs (Sus scrofa)
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在梅山与荷兰大白猪和长白猪杂交的实验中，对619头f2猪及其亲本进行了覆盖整个猪基因组的分子标记分型。研究了这些标记与两种肥胖特征：肌内脂肪含量和背脂肪厚度之间的关系。采用区间定位回归方法对两种遗传模型进行关联分析：(1)近交系模型，假设不同QTL等位基因的始祖系是固定的；(2)在19个同父异母的兄弟姐妹家庭中，每个家庭都具有独特的等位基因替代效应。两种方法都显示背膘厚度在7号染色体上有一个非常显著的QTL，并暗示在2号染色体上有一个QTL。此外，在杂交模式下，在1号和6号染色体上检测到影响背膘厚度的提示QTL。对于肌内脂肪含量，交叉法显示了2号、4号和6号染色体上的QTL，而半同胞分析显示了4号和7号染色体上的连锁。QTL效应的性质和两种模型的假设可以解释两种模型下发现的差异。结果表明，这两种方法在近交系资料分析中是互补的。无QTL零假设下的检验统计量为个体j的性状，原始源与被试相关。共10000人；是对同父异母家庭的平均影响吗？B表示回归足以估计染色体5，半同胞家族内系数I（即1的替代效应）和0.1%显著性阈值。估计较小的风险（假定的QTL）；xij是单个级别的条件概率，排列数量扩展到50,000。它是BFT或IMF较高的值。如果能够明确地推断出哪个父系的标记等位基因来自眉山，那么就可以确定这个mei - han等位基因是否与标记显著性的增加或减少有关
In an experimental cross between Meishan and Dutch Large White and Landrace lines, 619 F 2 animals and their parents were typed for molecular markers covering the entire porcine genome. Associations were studied between these markers and two fatness traits: intramuscular fat content and backfat thickness. Association analyses were performed using interval mapping by regression under two genetic models: (1) an outbred line-cross model where the founder lines were assumed to be fixed for different QTL alleles; and (2) a half-sib model where a unique allele substitution effect was fitted within each of the 19 half-sib families. Both approaches revealed for backfat thickness a highly significant QTL on chromosome 7 and suggestive evidence for a QTL at chromosome 2. Furthermore, suggestive QTL affecting backfat thickness were detected on chromosomes 1 and 6 under the line-cross model. For intramuscular fat content the line-cross approach showed suggestive evidence for QTL on chromosomes 2, 4, and 6, whereas the half-sib analysis showed suggestive linkage for chromosomes 4 and 7. The nature of the QTL effects and assumptions underlying both models could explain discrepancies between the findings under the two models. It is concluded that both approaches can complement each other in the analysis of data from outbred line crosses. the test statistic under the null hypothesis of no QTL is the trait of individual j , originating sire associated with the under study. A total of 10,000 ; is the average effect for half-sib family i ; b is the regression were sufficient to estimate chromosomewise 5, coefficient within half-sib family i ( i.e. , substitution effect for 1, and 0.1% significance thresholds. To estimate smaller risk a putative QTL); x ij is the conditional probability for individual levels the number of permutations was extended to 50,000. e ij the higher BFT or IMF. If it could be inferred unequivocally which of the sire’s marker alleles originated from the Meishan it could subsequently be determined whether this Meis-this han allele was associated with an increase or a decrease in marker Significance take