Pitel F, Bergé R, Coquerelle G, Crooijmans R P, Groenen M A, Vignal A, Tixier-Boichard M
Laboratoire de génétique cellulaire, Département de génétique animale, Institut national de la recherche agronomique, 31326 Castanet-Tolosan Cedex, France.
Genet Sel Evol. 2000 Jan-Feb;32(1):73-86. doi: 10.1186/1297-9686-32-1-73.
The bulked segregant analysis methodology has been used to map, with microsatellite markers, two morphological mutations in the chicken: polydactyly (PO) and naked neck (NA). These autosomal mutations show partial dominance for NA, and dominance with incomplete penetrance for PO. They were mapped previously to different linkage groups of the classical map, PO to the linkage group IV and NA being linked to the erythrocyte antigen CPPP. An informative family of 70 offspring was produced by mating a sire, heterozygous for each of the mutations, to 7 dams homozygous recessive for each locus. Three DNA pools were prepared, pool PO included 20 chicks exhibiting at least one extra-toe, pool NA included 20 non-polydactyly chicks showing the typical phenotype associated with heterozygosity for the naked neck mutation, and pool NP included 20 chicks exhibiting neither of the mutant phenotypes. Typings were done on an ABI-373 automatic sequencer with 147 microsatellite markers covering most of the genome. An unbalanced distribution of sire marker alleles were detected between pool PO, and pools NA and NP, for two markers of chromosome 2p, MCW0082 and MCW0247. A linkage analysis taking into account the incomplete penetrance of polydactyly (80% ) was performed with additional markers of this region and showed that the closest marker to the PO locus was MCW0071 (5 cM, lod score = 9). MCW0071 lies within the engrailed gene EN2 in the chicken. In the mouse, the homologous gene maps on chromosome 5, close to the hemimelic extra-toes mutation Hx. In the case of the NA locus, markers of chromosome 3 were selected because CPPP was mapped on this chromosome. Analysis of individual typings showed a linkage of 5.7 cM (lod score = 13) between the NA locus and ADL0237 in the distal region of chromosome 3q. These results contribute to connecting the former classical map to the molecular genetic map of the chicken, and open the way to the identification of the molecular nature of two developmental mutations of the chicken that are known to occur in many breeds of chickens.
多趾（PO）和裸颈（NA）。这些常染色体突变中，NA表现为部分显性，PO表现为显性但具有不完全外显率。它们先前被定位到经典图谱的不同连锁群上，PO位于连锁群IV，NA与红细胞抗原CPPP连锁。通过将每个突变均为杂合子的父本与每个位点均为纯合隐性的7只母本交配，产生了一个包含70只后代的信息丰富的家系。制备了三个DNA池，PO池包含20只表现出至少一个额外脚趾的雏鸡，NA池包含20只非多趾雏鸡，这些雏鸡表现出与裸颈突变杂合性相关的典型表型，NP池包含20只既不表现出任何一种突变表型的雏鸡。使用覆盖基因组大部分区域的147个微卫星标记在ABI - 373自动测序仪上进行分型。在2号染色体p臂的两个标记MCW0082和MCW0247上，检测到PO池与NA池和NP池之间父本标记等位基因的不平衡分布。利用该区域的其他标记进行了考虑多趾不完全外显率（80%）的连锁分析，结果表明与PO位点最接近的标记是MCW0071（5厘摩，lod分数 = 9）。MCW0071位于鸡的engrailed基因EN2内。在小鼠中，同源基因定位于5号染色体上，靠近半肢多指突变Hx。对于NA位点，由于CPPP定位于3号染色体，因此选择了该染色体的标记。对个体分型的分析表明，NA位点与3号染色体q臂远端区域的ADL0237之间存在5.7厘摩的连锁（lod分数 = 13）。这些结果有助于将先前的经典图谱与鸡的分子遗传图谱联系起来，并为鉴定鸡的两种发育突变的分子本质开辟了道路，这两种突变在许多鸡品种中都有发生。
