Evolution of pigment synthesis pathways by gene and genome duplication in fish
Evolution of pigment synthesis pathways by gene and genome duplication in fish
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DOI：
10.1186/1471-2148-7-74
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发表时间：
2007-05-11
影响因子：
3.4
通讯作者：
Volff, Jean-Nicolas
中科院分区：
文献类型：
--
作者：
Braasch, Ingo;Schartl, Manfred;Volff, Jean-Nicolas
背景：颜色和颜色图案属于动物中最多样化的表型性状。特别是硬骨鱼拥有更多的色素细胞类型比任何其他组的脊椎动物。作为古鱼类特异性基因组复制（FSGD）的结果，硬骨鱼基因组可能比四足动物包含更多的色素细胞发育相关基因拷贝。迄今为止，对于鱼类的色素基因，还没有一个系统的基因组清单可以用来检验这一假设，而且关于这些基因在不同鱼类谱系中的进化情况几乎一无所知。利用比较基因组学方法，包括系统发育重建和同线性分析，我们研究了硬骨鱼的两个主要色素合成途径，黑色素和蝶啶途径，不同类型的基因复制。编码参与酪氨酸合成黑色素的四种酶中的三种的基因在FSGD后被保留为重复。在蝶啶途径中，观察到两例源自FSGD的重复基因以及几种谱系特异性基因重复。在这两种途径中，编码限速酶酪氨酸酶和GTP-环水解酶I（GchI）的基因与四足动物相比，在硬骨鱼中具有额外的旁系同源物，它们是通过不同的复制模式产生的.我们还观察到以前未被认识的gchI基因在脊椎动物的多样性。此外，我们还发现了重复色素沉着基因的不同分辨率的证据，即。例如，结论：硬骨鱼类的色素合成基因库明显比其他脊椎动物类群的色素合成基因库大，这主要是由于FSGD所致。我们的研究结果支持了FSGD和其他类型的复制在鱼类色素沉着的进化中的重要作用。
Background: Coloration and color patterning belong to the most diverse phenotypic traits in animals. Particularly, teleost fishes possess more pigment cell types than any other group of vertebrates. As the result of an ancient fish- specific genome duplication ( FSGD), teleost genomes might contain more copies of genes involved in pigment cell development than tetrapods. No systematic genomic inventory allowing to test this hypothesis has been drawn up so far for pigmentation genes in fish, and almost nothing is known about the evolution of these genes in different fish lineages.Results: Using a comparative genomic approach including phylogenetic reconstructions and synteny analyses, we have studied two major pigment synthesis pathways in teleost fish, the melanin and the pteridine pathways, with respect to different types of gene duplication. Genes encoding three of the four enzymes involved in the synthesis of melanin from tyrosine have been retained as duplicates after the FSGD. In the pteridine pathway, two cases of duplicated genes originating from the FSGD as well as several lineage- specific gene duplications were observed. In both pathways, genes encoding the rate- limiting enzymes, tyrosinase and GTP- cyclohydrolase I ( GchI), have additional paralogs in teleosts compared to tetrapods, which have been generated by different modes of duplication. We have also observed a previously unrecognized diversity of gchI genes in vertebrates. In addition, we have found evidence for divergent resolution of duplicated pigmentation genes, i. e., differential gene loss in divergent teleost lineages, particularly in the tyrosinase gene family.Conclusion: Mainly due to the FSGD, teleost fishes apparently have a greater repertoire of pigment synthesis genes than any other vertebrate group. Our results support an important role of the FSGD and other types of duplication in the evolution of pigmentation in fish.