Long A D, Mullaney S L, Reid L A, Fry J D, Langley C H, Mackay T F
Center for Population Biology, University of California, Davis 95616, USA.
Genetics. 1995 Mar;139(3):1273-91. doi: 10.1093/genetics/139.3.1273.
Factors responsible for selection response for abdominal bristle number and correlated responses in sternopleural bristle number were mapped to the X and third chromosome of Drosophila melanogaster. Lines divergent for high and low abdominal bristle number were created by 25 generations of artificial selection from a large base population, with an intensity of 25 individuals of each sex selected from 100 individuals of each sex scored per generation. Isogenic chromosome substitution lines in which the high (H) X or third chromosome were placed in an isogenic low (L) background were derived from the selection lines and from the 93 recombinant isogenic (RI) HL X and 67 RI chromosome 3 lines constructed from them. Highly polymorphic neutral roo transposable elements were hybridized in situ to the polytene chromosomes of the RI lines to create a set of cytogenetic markers. These techniques yielded a dense map with an average spacing of 4 cM between informative markers. Factors affecting bristle number, and relative viability of the chromosome 3 RI lines, were mapped using a multiple regression interval mapping approach, conditioning on all markers > or = 10 cM from the tested interval. Two factors with large effects on abdominal bristle number were mapped on the X chromosome and five factors on the third chromosome. One factor with a large effect on sternopleural bristle number was mapped to the X and two were mapped to the third chromosome; all factors with sternopleural effects corresponded to those with effects on abdominal bristle number. Two of the chromosome 3 factors with large effects on abdominal bristle number were also associated with reduced viability. Significant sex-specific effects and epistatic interactions between mapped factors of the same order of magnitude as the additive effects were observed. All factors mapped to the approximate positions of likely candidate loci (ASC, bb, emc, h, mab, Dl and E(spl), previously characterized by mutations with large effects on bristle number.
将负责腹部刚毛数选择反应以及与胸骨侧刚毛数相关反应的因素定位到黑腹果蝇的X染色体和第三条染色体上。通过从一个大的基础群体中进行25代人工选择，创建了腹部刚毛数高和低的品系，每代从每性别100个评分个体中选择25个各性别的个体，选择强度为25。从选择品系以及由它们构建的93个重组近交（RI）HL X品系和67个RI第三条染色体品系中获得了同基因染色体替代品系，其中高（H）X或第三条染色体被置于同基因低（L）背景中。高度多态性的中性roo转座元件原位杂交到RI品系的多线染色体上，以创建一组细胞遗传学标记。这些技术产生了一个密集的图谱，信息性标记之间的平均间距为4厘摩。使用多元回归区间作图方法，以距离测试区间≥10厘摩的所有标记为条件，对影响刚毛数和第三条染色体RI品系相对活力的因素进行定位。对腹部刚毛数有大影响的两个因素定位在X染色体上，五个因素定位在第三条染色体上。对胸骨侧刚毛数有大影响的一个因素定位到X染色体上，两个因素定位到第三条染色体上；所有对胸骨侧有影响的因素都与对腹部刚毛数有影响的因素相对应。对腹部刚毛数有大影响的第三条染色体上的两个因素也与活力降低有关。观察到与加性效应数量级相同的显著性别特异性效应和定位因素之间的上位性相互作用。所有定位的因素都位于可能的候选基因座（ASC、bb、emc、h、mab、Dl和E(spl)）的大致位置，这些基因座先前已通过对刚毛数有大影响的突变进行了表征。
