Mutations in the agouti (ASIP), the extension (MC1R), and the brown (TYRP1) loci and their association to coat color phenotypes in horses (Equus caballus)
Mutations in the agouti (ASIP), the extension (MC1R), and the brown (TYRP1) loci and their association to coat color phenotypes in horses (Equus caballus)
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DOI：
10.1007/s003350020017
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发表时间：
2001-06-01
期刊：
影响因子：
2.5
通讯作者：
Guérin, G
中科院分区：
文献类型：
--
作者：
Rieder, S;Taourit, S;Guérin, G
毛色遗传学在成功地适应和应用于不同的哺乳动物物种时，很好地展示了比较遗传学的强大概念。利用跨物种技术，克隆、测序和鉴定了马黑素皮质素受体(MCIR)和刺鼠信号蛋白(ASIP)，完成了酪氨酸酶相关蛋白1(TYRP1)的部分序列，对40匹马和120匹马的这些基因的编码序列和侧翼区的部分序列进行了系统分析。我们的小组代表了22个不同的马种，包括11种不同的马毛色。对11个毛色表型的MCIR的1721bp的基因组片段进行比较，发现除已知的板栗等位基因(C90IT)外，没有序列差异。在一个4994bp的基因组片段中，发现了两个内含子碱基替换(SNP-A845G和C2374A)，一个位于3‘-UTRs的点突变(A4734G)，一个位于外显子2(ADEx2)的缺失(ADEx2)。在本课题组9个不同品种的24匹黑马中，发现该缺失是纯合子的，并与隐性黑毛色(A(A)/A(A))完全相关。由ADEx2启动的移码被认为改变了正常的编码序列，作为功能丧失的ASIP突变。在TYRP1中，在外显子2(C189T)检测到碱基替换，导致苏氨酸到蛋氨酸的未知功能变化，在内含子2中发现SNP(A1188G)。
Coat color genetics, when successfully adapted and applied to different mammalian species, provides a good demonstration of the powerful concept of comparative genetics. Using cross-species techniques, we have cloned, sequenced, and characterized equine melanocortin-1-receptor (MCIR) and agouti-signaling-protein (ASIP), and completed a partial sequence of tyrosinase-related protein 1 (TYRP1).The coding sequences and parts of the flanking regions of those genes were systematically analyzed in 40 horses and mutations typed in a total of 120 horses. Our panel represented 22 different horse breeds, including 11 different coat colors of Equus caballus. The comparison of a 1721-bp genomic fragment of MCIR among the 11 coat color phenotypes revealed no sequence difference apart from the known chestnut allele (C90IT). In particular, no dominant black (E-D) mutation was found.In a 4994-bp genomic fragment covering the three putative exons, two introns and parts of the 5'- and 3'-UTRs of ASIP, two intronic base substitutions (SNP-A845G and C2374A), a point mutation in the 3'-UTRs (A4734G), and an 11-bp deletion in exon 2 (ADEx2) were detected. The deletion was found to be homozygous and completely associated with horse recessive black coat color (A(a)/A(a)) in 24 black horses out of 9 different breeds from our panel. The frameshift initiated by ADEx2 is believed to alter the regular coding sequence, acting as a loss-of-function ASIP mutation. In TYRP1 a base substitution was detected in exon 2 (C189T), causing a threonine to methionine change of yet unknown function, and an SNP (A1188G) was found in intron 2.