G3 (Bethesda). 2012 Jun;2(6):707-20. doi: 10.1534/g3.112.001990. Epub 2012 Jun 1.
Growth performance and reduced stress response are traits of major interest in fish production. Growth and stress-related quantitative trait loci (QTL) have been already identified in several salmonid species, but little effort has been devoted to charrs (genus Salvelinus). Moreover, most QTL studies to date focused on one or very few traits, and little investigation has been devoted to QTL identification for gene expression. Here, our objective was to identify QTL for 27 phenotypes related to growth and stress responses in brook charr (Salvelinus fontinalis), which is one of the most economically important freshwater aquaculture species in Canada. Phenotypes included 12 growth parameters, six blood and plasma variables, three hepatic variables, and one plasma hormone level as well as the relative expression measurements of five genes of interest linked to growth regulation. QTL analysis relied on a linkage map recently built from S. fontinalis consisting of both single-nucleotide polymorphism (SNP, n = 266) and microsatellite (n =81) markers in an F(2) interstrain hybrid population (n = 171). We identified 63 growth-related QTL and four stress-related QTL across 18 of the 40 linkage groups of the brook charr linkage map. Percent variance explained, confidence interval, and allelic QTL effects also were investigated to provide insight into the genetic architecture of growth- and stress-related QTL. QTL related to growth performance and stress response that were identified could be classified into two groups: (1) a group composed of the numerous, small-effect QTL associated with some traits related to growth (i.e., weight) that may be under the control of a large number of genes or pleiotropic genes, and (2) a group of less numerous QTL associated with growth (i.e., gene expression) and with stress-related QTL that display a larger effect, suggesting that these QTL are under the control of a limited number of genes of major effect. This study represents a first step toward the identification of genes potentially linked to phenotypic variation of growth and stress response in brook charr. The ultimate goal is to provide new tools for developing Molecular Assisted Selection for this species.
生长性能和应激反应降低是鱼类生产中主要关注的特征。已经在几种鲑鱼物种中鉴定出与生长和应激相关的数量性状基因座（QTL），但在拟沙丁鱼属（Charrs）中几乎没有进行过相关研究。此外，迄今为止大多数 QTL 研究都集中在一个或少数几个性状上，而对基因表达的 QTL 鉴定研究较少。在这里，我们的目标是鉴定与生长和应激反应相关的 27 个表型的 QTL，这些表型在加拿大最具经济价值的淡水养殖鱼类之一的河鳟（Salvelinus fontinalis）中。表型包括 12 个生长参数、6 个血液和血浆变量、3 个肝变量和 1 个血浆激素水平，以及与生长调节相关的 5 个感兴趣基因的相对表达测量。QTL 分析依赖于最近从 S. fontinalis 构建的连锁图谱，该图谱由 F2 杂交种群（n = 171）中的单核苷酸多态性（SNP，n = 266）和微卫星（n = 81）标记组成。我们在河鳟的 40 个连锁群中的 18 个中鉴定出 63 个与生长相关的 QTL 和 4 个与应激相关的 QTL。还研究了遗传方差解释百分比、置信区间和等位 QTL 效应，以深入了解与生长和应激相关 QTL 的遗传结构。鉴定出的与生长性能和应激反应相关的 QTL 可以分为两类：（1）一组由与生长相关的一些性状（如体重）相关的大量小效应 QTL 组成，这些 QTL 可能受大量基因或多效基因的控制，以及（2）一组数量较少的 QTL 与生长（即基因表达）和与应激相关的 QTL 相关，这些 QTL 表现出较大的效应，表明这些 QTL 受少数主要效应基因的控制。这项研究代表了鉴定河鳟生长和应激反应表型变异相关基因的第一步。最终目标是为该物种的分子辅助选择提供新的工具。
