The Expression Analysis Of Ghr1 And Igf1 During Different Developmental Stages In Nile Tilapia (Oreochromis Niloticus) And Blue Tilapia (Oreochromis Aureus)

GHR and IGF1 are important parts of GH/IGF1 axis, which regular the growth of animals. The expression of ghr and igfl are highly associated with body weight, so they are regarded as two candidate genes in research on growth Tilapia is an important fish specie that have been farmed worldwide. In this study, a 200-day growth comparative experience of Nile tilapia (Oreochromis niloticus) and Blue tilapia(Oreochromis aureus) was proceeded. Using Real-time quantitative PCR (Q-PCR) the ghrl and igfl mRNA abundance was detected in hepatic and muscular tissues of the two different tilapia species It is aimed to provide theoretical evidence to further study on mechanism of GH/IGF1 axis gene and molecular selection of tilapia breedings.Using β-actin as house-keeping gene and SYBR Green dye, the Q-PCR experience platform has been founded. Plasmids contain ghrl, igfl, β-actin fragment were constructed as standard templet. Q-PCR was employed with 5 serial dilution standard plasmid by 3 times parallel control to obtain standard curve. The result showed that ghrl, igfl,β-actin standard cuver have a good linearity. R2 value was 0.999,0.993,0.998. Dissociation analysis displayed that the dissociation curve only appeared one summit so the ghrl, igfl,β-actin Q-PCR products were specific. In conclusion, the Q-PCR experience platform was reliable and effective and can be used in further research.ghrl and igfl expression was analyzed during different developmental stages of two tilapia species using the experience platform. The expression level of ghrl and igf1 in liver and muscle were quantified by Q-PCR on days 0,20,40,60,80,125, 145,165,185,205. The results showed that developmental period of body weight in tested fish can be divided into different stages:rapid growth stage(RGS) and stationary growth stage(SGS), the body growth in 0-40/145-165days was more quickly than 40-145 days. In 0-40/145-165 days, the hepatic gene expression level of ghrl and igfl were higher than 40-145 days, sharing the same trend with the tendency of body weight development. In muscle, the ghrl has an similar but lagged pattern with hepatic ghrl mRNA about 20 days. Muscular igfl mRNA level of two tilapia species was about 2 orders of magnitude lower than liver, and there was a different expression pattern between Nile tilapia and Blue tilapia In conclusion, the expression of ghrl and igfl differed with temporal and tissue-specific characteristics. The developmental changes of hepatic ghrl and igfl mRNA may be a key factor to different growth speed in developmental stages in Nile tilapia and Blue tilapia. Besides, the different expression of muscular igfl between Nile tilapia and Blue tilapia implied different mechanism of IGF1 secretion and regulatory in muscle between two species.