Molecular mechanisms regulating globin gene expression in fish

我们克隆了8个鲤鱼α-和β-珠蛋白基因位点（No. 1 - 8）。RT-PCR分析了这三种不同类型的珠蛋白基因在发育过程中的表达模式。在3个α-珠蛋白基因（1 α、2 α和8 α）中，1 α基因在发育早期表达，但表达量很快下降。8 α基因在胚胎中显著表达，孵化后表达减弱。幼鱼期2 α基因表达量最高，成鱼期1 α基因表达量最高。在3个β-珠蛋白基因（1 β、2 β和8 β）中，表达模式与α-珠蛋白基因相似。上述结果表明，1型α-和β-珠蛋白基因为胚胎型和成体型，2型和8型珠蛋白基因为幼虫型。我们扩增了条纹鲈鱼α-和β-珠蛋白基因2外显子内的区域并对其进行了测序。通过DNA和预测氨基酸序列鉴定出3个α-珠蛋白基因和5个β-珠蛋白基因。鱼类α-珠蛋白和β-珠蛋白第2外显子区域氨基酸序列的系统发育树分析表明，黑鲈α-珠蛋白和β-珠蛋白均可分为2类。系统发育树还表明，鱼类珠蛋白基因的分化是在与其他脊椎动物分化后发生的。一组可能是成体型珠蛋白，另一组可能是胚胎期或非成体期珠蛋白。系统发育树还表明，珠蛋白基因在鱼类中的分化独立于它们在陆地脊椎动物中的分化。

We cloned eight carp α- and β-globin gene loci (No. 1 - 8). An RT-PCR analysis was performed to investigate the expression pattem of these three different types of globin genes during development. Among the three α-globin genes (1 α, 2 α, and 8 α), the 1 α gene was expressed in the early developmental stage but its expression soon decreased. The 8 α gene was dominantly expressed in embryos, but was diminished after hatching. At the juvenile stage, the 2 α gene showed the highest expression, while in the adults, the 1 α showed the highest expression. Among the three β-globin genes (1 β, 2 β, and 8 β), the expression pattem is similar to those of the α-globin genes. These results indicate that type 1 carp α- and β-globin genes are embryo and adult types, and the type 2 and 8 globin genes are larval types.We amplified and sequenced the region within the 2nd exon of α- and β-globin genes of striped bass, Morone saxatilis. Three α-globin and 5 β-globin genes were identified by the DNA and predicted amino acid sequences. The phylogenetic tree of the amino acid sequences of the region within the 2nd exon of fish α- and β-globin showed that both the α-globins and the β-globins of striped bass could be divided into 2 groups. The phylogenetic tree also indicated that the divergence of fish globin genes were occured after diverged from other vertebrates. One group may be adult-type globins and the other may be embryo or non-adult stage globins. The phylogenetic tree also suggested that the globin genes have diverged in fishes independently from their divergence in land vertebrates.