| NADH dehydrogenase subunit1gene and NADH dehydrogenase subunit2genes are two of mtDNA protein coding genes, they are the two subunits of the NADH dehydrogenase is a major component of the respiratory chain complex I in the respiratory chain directly involved in hydrogen and electron transfer to produce the ATP through oxidative phosphorylation, thereby involved in energy metabolism. Preliminary studies of our group found that30%of the energy restricted group showed significant effect on mitochondrial ND1gene expression in chicken liver (P<0.05). And it also showed the down regulated. From it now on the mitochondrial gene is mainly focused on molecular evolution and phylogenetic. The mitochondrial genes showed collection with meat quality traits in Japanese black cattle. And mtDNA polymorphisms showed collection with higher milk yield and lower milk fat rate in cows.In order to study genetic variation and its potential effects of chicken ND1, ND2gene, this experiment conducted a study on the genetic variation between the species of ND1and ND2gene. The results showed that among the eight chicken species, only a variable sites mt.NDl4589A>G had been detected in ND1among the eight chicken species. And it was found a silent heteroplasmic mutation by PCR-RFLP method and the ratio of the heteroplasmy was6.3%;17variants had been detected in the ND2gene, including six missense mutations,11silent mutations, which15haplotypes were discovered involving via constructing haplotypes with software. And the haplotype diversity (haplotype diversity, hd) was0.7692. Two missense mutations mt.ND25703A>T and mt.ND25727T>G had been selected in the ND2gene had the heteroplasmic sites by CRS-PCR-RFLP method, the heteroplasmic ratio was6.3%and3.8%, respectively.The study on distribution of three heteroplasmic variations in the Gushi chicken population revealed that in the F0, F1and F2the heteroplasmic ratios of mt.NDl 4589A>G were81%,41%and70%respectively. And the heteroplasmic ratios of mt.ND25703A>T in the F0, F1and F2were39%,14%and9%respectively. The heteroplasmic ratios of mt.ND25727T>G were16%,9%and40%in the same populations. The three results showed obvious heteroplasmic differences among the three sites. Association analysis of the variations and heteroplasmy with some traits in Gushi chicken F2population showed that mt.NDl4589A>G was significantly associated with abdominal fat, abdominal fat percentage, cecal length, and some other carcass indexs, growth traits and serum biochemical indexes. Especially the heteroplasmic of mt.NDl4589A>G was significantly associated with leg muscle weight. The mt.ND25703A>T and mt.ND25727T>G were not only significant correlation with the pectoral muscle fat content and fat traits, but also significant associated with growth traits, carcass indexs, serum biochemical indexs. The heteroplasmy of mt.ND25703A>T and mt.ND25727T>G were significant association with the muscular stomach weight rat and wings heavy rate. It generally showed that there were potentially extensive effects of the three variation sites.RT-PCR and quantitative PCR were adopted to study the expression characterization of ND2. The results showed that it was significant differentially expressed in15tissues, with the lowest expression level in pancreas, the highest expression in heart and a higher expression level in kidney. And the expreesion in heart and kidney were about24and17.5times than that in pancreas, respectively. It also found that in30%of the energy restricted group the mitochondrial ND2gene expressing had no significant impact on chicken liver tissue (P>0.05). This study firstly reported mitochondrial heteroplasmy in chicken. And it also the first time to indicate that heteroplasmic variation had significant effect on growth traits, carcass parameters and serum biochemical indicators, which showed the potential importance of related variation. |
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