In fish and other vertebrates, growth hormone (GH) is an essential polypeptide required for normal growth and development. In an attempt to understand growth regulation in yellowtail kingfish (YTK), the full-length cDNA sequences encoding gh and its receptors (ghr1 and ghr2) were cloned, characterized and the expression profiles of these three genes were investigated during embryonic development. The full-length cDNA sequences of GH and its receptors were obtained by RT-PCR combined with RACE methord. YTK gh cDNA sequence was 852 base pairs (bp) that comprised an open reading frame (ORF) of 615 bp encoding a 204-amino acids (aa) precursor. The preprohormone compassed a signal peptide (17 aa) and the mature peptide (187 aa). YTK GHR1 protein consisted of a signal peptide (28 aa), an extracellular domain (222 aa), a single transmembrane domain (23 aa) and an intracellular domain (361 aa). GHR2 protein included 18 aa, 223 aa, 23 aa, and 321 aa, respectively. Tissue distribution analysis showed that the maximal level of gh expression was observed in the pituitary, and ghr1 mRNA was mainly detected in the liver, while ghr2 transcripts were most abundant in the gonad. Moreover, both ghr1 and ghr2 mRNAs were expressed in all embryonic stages and displayed different gene expression profiles. Overall, these results provide initial evidences for the involvement of the GH/GHR system in the early ontogeny of yellowtail kingfish.

在鱼类和其他脊椎动物中，生长激素（GH）是正常生长发育所必需的必需多肽。为了了解黄尾鱼（YTK）的生长调控，克隆了编码gh及其受体（ghr1和ghr2）的全长cDNA序列，进行了表征，并在胚胎发育过程中研究了这三个基因的表达谱。通过RT-PCR结合RACE方法获得了GH及其受体的全长cDNA序列。YTK ghcDNA序列为852个碱基对（bp），包含615 bp的开放阅读框（ORF），编码204个氨基酸（aa）的前体。前激素原包围信号肽（17aa）和成熟肽（187aa）。YTK GHR1蛋白由信号肽（28aa），细胞外结构域（222aa），单个跨膜结构域（23aa）和细胞内结构域（361aa）组成。GHR2蛋白分别包括18个氨基酸，223个氨基酸，23个氨基酸和321个氨基酸。组织分布分析表明，垂体中观察到最大的gh表达水平，主要在肝脏中检测到ghr1 mRNA，而性腺中ghr2转录本最丰富。而且，ghr1和ghr2mRNA在所有胚胎阶段均表达，并显示出不同的基因表达谱。总的来说，这些结果为GH / GHR系统参与黄尾king早期个体发育提供了初步证据。