| Uncoupling proteins are member of the mitochondrial membrane transporter family, present in the mitochondrial inner membrane that mediate a regulated discharge of the proton gradient that is generated by the respiratory chain and diminishing the resulting production of ATP and instead yielding dissipative heat. This energy-dissipater mechanism can be associated with the metabolism of fat and regulation the energy expenditure. Several proofs demonstrated that UCP gene partially explains the occurrence of obesity. So UCP gene can be viewed as the candidate gene that impact chicken body composition and growth traits. Several SNPs of chicken UCP gene were newly found and genotyped in the population of China native breeds, AA broiler and Hyline layer by the methods of PCR-SSCP, PCR-RFLP and Direct sequencing. The correlation analysis between the polymorphisms of UCP gene and the growth as well as body composition traits in CAU F2 population and NEAU broiler lines divergent selection for abdominal fat were carried out use the appropriate mixed model. RT-PCR and. Northern Blot methods were developed to investigate the expression of the UCP gene in heart, liver, spleen, lung, kidney, stomach, intestine, brain, muscle, and adipose. Quantitative RT-PCR methods were developed to measure the UCP gene mRNA expression level considering the factor of breed, age, feed types and insulin treat. The chicken UCP introns were cloned, sequenced and submitted to GenBank (Accession No. AF433170). The phylogenetic trees were constructed based on the sequence of cds region as well as of intron2, intron3 region. These results showed:(1) Seven SNPs were found in various region of chicken UCP gene. Those are C1351T, G1412A, C1191T and A1197C located in 3'UTR region, C1240A, C883A in the intron2 region (Accession No. AF433170) and T660C (Accession No.AF287144) in the exon2 region.(2) Population genetic analysis of four SNPs in the 3'UTR region in different breeds showed that the frequency of genotypes (AA, AB, BB) caused by SNPs of C1351T and G1412A were significantly different between Beijing You and Shiqiza, Baier, layer (P<0.01). Genotypes frequencies of C1191T (FF, FG, GG) were significantly different between Beijing You and Layer, Baier (P<0.01), as well as AA broiler and Baier, shiqiza (P<0.05). For SNP A1197C, the frequency of genotypes (HH, HI, II) were no significant differenent between Beijing You and AA broiler as well as Baier and Layer (P>0.05), however, among other tested breeds the difference was significant (P<0.01).(3) Results of association analysis between the UCP SNPs and growth as well as body composition traits showed that the UCP gene had the effect on the traits such as body weight AFW, AFPand liver weight in chicken. In F2 population, the AB birds had significant higher LW, LW/CW than AA and BB birds (P<0.05); LWP in BB birds was higher than AA and AB birds (PO.05). In the fifth and sixth population of divergent selection for abdominal fat broiler line II birds had lower AF and AFP than HH and HI birds (P<0.05). In F2 population,BW of HH and HI birds from 6 weeks of age to 10 weeks of age were higher than II birds (P<0.01). MM, MN genotype birds (SNP of C1240A in intron2) had greater BW, CW and LW than NN birds (P<0.05). The additive effects of M allele to LW and CW were 64.Ig and 50g. OO birds had greater SW than PP and OP birds(P<0.05).(4) Chicken UCP gene was only expressed in muscle.(5) Difference of UCP gene mRNA expression level was existed between broiler and layer. Energy level of feed could influence the expression level of UCP gene in broiler and layer. The UCP gene expression level was higher in broiler than layer at new hatch chickens. After six weeks of age, layer's UCP gene expression level became higher than broiler's. With age increasing the UCP gene expression level was become lower in broiler and layer, In broiler, UCP expression level in the group of feed with broiler-type-feed was higher than the group feed with layer-type-feed. However the same rule was not observed in lay...
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