Smith J J, Kump D K, Walker J A, Parichy D M, Voss S R
Department of Biology, University of Kentucky, Lexington, Kentucky 40506, USA.
Genetics. 2005 Nov;171(3):1161-71. doi: 10.1534/genetics.105.046433. Epub 2005 Aug 3.
Expressed sequence tag (EST) markers were developed for Ambystoma tigrinum tigrinum (Eastern tiger salamander) and for A. mexicanum (Mexican axolotl) to generate the first comprehensive linkage map for these model amphibians. We identified 14 large linkage groups (125.5-836.7 cM) that presumably correspond to the 14 haploid chromosomes in the Ambystoma genome. The extent of genome coverage for these linkage groups is apparently high because the total map size (5251 cM) falls within the range of theoretical estimates and is consistent with independent empirical estimates. Unlike most vertebrate species, linkage map size in Ambystoma is not strongly correlated with chromosome arm number. Presumably, the large physical genome size ( approximately 30 Gbp) is a major determinant of map size in Ambystoma. To demonstrate the utility of this resource, we mapped the position of two historically significant A. mexicanum mutants, white and melanoid, and also met, a quantitative trait locus (QTL) that contributes to variation in metamorphic timing. This new collection of EST-based PCR markers will better enable the Ambystoma system by facilitating development of new molecular probes, and the linkage map will allow comparative studies of this important vertebrate group.
我们开发了虎纹钝口螈（东部虎螈）和墨西哥钝口螈的表达序列标签（EST）标记，以生成这些模式两栖动物的首张综合连锁图谱。我们确定了14个大的连锁群（125.5 - 836.7厘摩），推测它们对应于钝口螈基因组中的14条单倍体染色体。这些连锁群的基因组覆盖范围显然很高，因为总图距大小（5251厘摩）落在理论估计范围内，并且与独立的经验估计一致。与大多数脊椎动物物种不同，钝口螈的连锁图谱大小与染色体臂数没有强烈相关性。据推测，巨大的物理基因组大小（约300亿碱基对）是钝口螈图谱大小的主要决定因素。为了证明这一资源的实用性，我们定位了两个具有历史意义的墨西哥钝口螈突变体——白色和黑色突变体的位置，以及一个影响变态时间变异的数量性状位点（QTL）——met。这个基于EST的PCR标记新集合将通过促进新分子探针的开发更好地推动钝口螈研究系统的发展，而连锁图谱将有助于对这个重要脊椎动物群体进行比较研究。
