金钱鱼IGF-1和IGF-2的克隆及其在胚胎发育过程的表达

Insulin-like Growth Factors 1 and 2 in Spotted Scat(Scatophagus argus): Molecular Cloning and Differential Expression During Embryonic Development

【目的】克隆金钱鱼IGF-1和IGF-2基因,研究二基因在金钱鱼胚胎发育过程中的表达。【方法】采用实时荧光定量PCR,以不同发育时间点的金钱鱼(Scatophagus argus)胚胎为实验材料,分析IGF-1和IGF-2基因在鱼类胚胎发育过程中的表达图式。【结果】金钱鱼IGF-1和IGF-2的蛋白全序列分别为186和215个氨基酸。序列分析表明,IGF-1和IGF-2均有胰岛素样生长因子蛋白典型结构,含有N端信号肽、B、C、A、D和E结构域,且有6个保守的半胱氨酸,与其他鲈形目鱼类花鲈的IGF-1和IGF-2相似性较高(95%和91%)。IGF-1从受精卵到出膜的胚胎发育过程中表达量逐渐上调;IGF-2在受精后至囊胚期表达量极低,而在原肠胚期和神经胚期表达量显著上调至最高水平,在神经胚期后表达量显著降低并维持稳定。【结论】IGF-1和IGF-2序列保守性低,与鲈形目同源性高,在金钱鱼胚胎发育过程中起不同调控作用。

【Objectives】Insulin-like growth factors-1 and-2（IGF-1 and 2） are critical factors involved in the regulation of embryonic development in vertebrates.【Method】In this study, temporal expression patterns throughout embryonic development were examined by quantitative real-time PCR assay.【Result】 Two IGF cDNAs, i.e. IGF-1 and IGF-2 mRNAs, were detected in embryonic stages of spotted scat by Real-Time PCR. The IGF-1 and IGF-2 cDNA sequences encoded proteins of 186 and 215 amino acid residues, respectively. IGF1 and IGF2 are sequentially composed of a signal peptide, B, C, A, D,E domains and six conservative cysteine residues. The deduced amino acid sequence of C. semilaevis IGF-I gene has highest identity with those of other perciformes fishes. IGF-1 mRNA level remained high from fertilized eggs to blastula. In contrast, IGF-2 mRNA level was low from fertilized eggs to blastula and peaked at gastrula and neurula followed by a gradual decrease. 【Conclusion】The spotted scat IGF-1 amino acid sequences shared the lower sequence identity with IGF-2, however, both of them have a higher homology with Perciformes, and play differential roles in the embryonic development of spotted scat.