Cloning And MRNA Expression Of GHRHR Gene In Tibetan Chicken,Luning Chicken And White Feather Broilers

In order to study the great Genetic differences in the growth rate between local chicken and white broiler chickens,GHRHR1 gene and GHRHR2 gene of white broiler chickens,Luning chicken and Tibetan chicken were cloned by RT-PCR technique.The expression of GHRHR1 and GHRHR2 genes of tissues(Pituitary,hypothalamus,heart,liver,spleen,lungs,leg muscles and pectoral muscles)in these chickens at different ages were detected by fluorescent quantitative technology and correlated with their growth performance.The results show:1.White broilers grew quickly in the early stages and reached a market weight of 2.5 kg or more at 42 days.Luning chickens grow faster than Tibetan chickens,but42-day-old the Luning chickens and Tibetan chickens have a body weight of only about 0.4 kg,which is less than that White broilers.2.The five genotypes of GHRHR1 gene and two genotypes of GHRHR2 gene were cloned from white broiler,Luning chickens and Tibetan chickens.All of them were unstable and hydrophobic acidic proteins.There are five mutation sites in the GHRHR1 gene sequence of Luining chicken,among of them,the mutation of 864 loci A?G resulted in the mutation of 288 locus a mino acids S?P.Transmembrane structure analysis of each putative protein revealed that GHRHR1,GHRHR1-V1 and GHRHR2 genes,all of them,have 7 membrane structures;GHRHR1-V2 and GHRHR1-V3 do not have transmembrane structures;The GHRHR1-V4 has a transmembrane structure;GHRHR2-V1 have 3 transmembrane structures.The GHRHR1,GHRHR1-V4,GHRHR2-V1 all of them,have a hormone receptor domain,and the other four proteins do not have this structure.Through the prediction of signal peptides,it was found that the seven proteins of the putative GHRHR all have signal peptide sequences and are secreted proteins.The predicted results of secondary structure showed that these seven proteins can form secondary structures such as?-helix,?-sheet and random coil.3.The GHRHR1 and GHRHR2 gene are mainly expressed in the pituitary andhypothalamus.The expression of pituitary was significantly higher than other tissues.The expression level of GHRHR1 in white broiler are highest than that of other chicken species,followed by Tibetan chickens and the lowest expression in Luining chickens.The expression level of GHRHR2 in Tibetan chickens is the highest,and the expression levels in white broiler and Luining chickens are basically similar.