Bennett B, Johnson T E
Institute for Behavioral Genetics, CB447, University of Colorado, Boulder, Colorado 80309-0447, USA.
Mamm Genome. 1998 Dec;9(12):969-74. doi: 10.1007/s003359900908.
Mouse strains congenic for individual quantitative trait loci (QTLs) conferring hypnotic sensitivity to ethanol were constructed by backcrossing genotypically selected ILS x ISS N2 individuals to either inbred Long Sleep (ILS) or inbred Short Sleep (ISS) mice. We used a novel "speed congenic" approach in which N2 mice were genotyped for markers flanking each of the five originally identified QTLs. Genotypic selection for ISS regions at four of the five QTLs, and for ILS/ISS at the fifth QTL, allowed rapid fixation of the genetic background. We call this strategy "QTL-Marker-Assisted Counter Selection" or QMACS. By the N4 generation, phenotypic assessments showed that in some sublines the QTL had not been captured; these sublines were discarded and positive lines split to create new replicate sublines. One QTL, on Chromosome (Chr) 8, was not confirmed. At the N8, virtually all sublines on the remaining QTLs retained the phenotypic difference between heterozygotes and ISS homozygotes. Small numbers of interim congenics were produced at the N6 and later generations in which the ILS QTL was made homozygous on the ISS background; as expected, these congenic mice showed an increased sleep time. For later backcrosses (after the N4), the parents were selected on the basis of phenotype as well as genotype. The parent-offspring correlation over all QTLs was significant, supporting the use of phenotypic selection in congenic construction.
通过将基因分型选择的ILS×ISS N2个体与近交系长睡眠（ILS）或近交系短睡眠（ISS）小鼠回交，构建了对乙醇催眠敏感性具有单个数量性状基因座（QTL）的同基因小鼠品系。我们采用了一种新颖的“快速同基因”方法，其中对N2小鼠进行基因分型，以确定最初鉴定的五个QTL中每个QTL侧翼的标记。对五个QTL中的四个QTL的ISS区域进行基因型选择，对第五个QTL进行ILS/ISS选择，从而快速固定遗传背景。我们将此策略称为“QTL标记辅助反选择”或QMACS。到N4代时，表型评估表明，在一些亚系中QTL未被捕获；这些亚系被丢弃，阳性品系进行分离以创建新的重复亚系。位于8号染色体（Chr）上的一个QTL未得到证实。在N8代时，其余QTL上的几乎所有亚系都保留了杂合子和ISS纯合子之间的表型差异。在N6代及以后的世代中产生了少量中间同基因系，其中在ISS背景上使ILS QTL纯合；正如预期的那样，这些同基因小鼠的睡眠时间增加。对于后来的回交（N4代之后），根据表型和基因型选择亲本。所有QTL上的亲子相关性都很显著，这支持了在同基因构建中使用表型选择。
