Molecular characterization of the growth hormone in Chinese sturgeon and its expression during embryogenesis and early larval stages

Chinese sturgeon (Acipenser sinensis Gray) has a fast growth rate starting in early larval stage. Likely, the fast growth is attributed to the growth hormone (GH); an essential polypeptide required for growth and development of vertebrates. In this study, GH cDNA was cloned from a pituitary library. The AsGH cDNA consists approximately 954 bp in size including a 16 bp 5'-untranslated region and 296 bp 3'-untranslated region. The open reading frame (642 bp) encodes a 214 amino acids (aa), which represents the precursor composed of a 25 aa signal peptide followed by a 189 aa mature polypeptide. The polyclonal antibody was prepared from the in vitro expressed mature protein. Western blot analysis showed a constant GH expression of a monomeric form in the 13 embryo stages and in several larval stages. Interestingly, two dimeric bands of GH were detected since day 3 in the hatched larvae. Our findings suggest that the GH may play important physiological functions in embryonic and larval development of Chinese sturgeon.