Study On Mitochondrial DNA Copy Number In Different Tissues Of Plateau And Lowland Tibetan Pig

Tibet pig is pecial swine widely distributed in plateau section, they are well-adapted and have high meat quality. Mitochondrion is the main place of oxidative phosphorylation and ATP producing, can provid ninety percent energy to the cells. Its copy number is positive correlation with metabolic capability and energy requirement. Pig, living in Songpan with an altitude of 3500 meters, called Tibet pig. Tibet pig, living in Jianyang with an altitude of 400 meters and breeding there more than 5 generations, called lowland Tibetan pig. To research the changes of the copy number of Mitochondrion, we measure the copy number of Mitochondrion in eight tissues, including brain, myocardium, liver, spleen, lung, kidney, longissimus dorsi, psoas, of three Tibetan pig living in Songpan and other three Tibetan pig living in Jianyang. And we analyzed the relationship of different tissues and different breeds, hoping to reveal the molecular mechanism of Tibetan pig’s lowland adaptability and providing some theoretical basis for the feeding of Tibetan pig in the lowland.Researches show that, to the mammal, Mitochondrion DNA may decrease with the growth with age. We measure the mtDNA by Long PCR, showing that the qulity of mtDNA is satisfactory. The result of Q-PCR show that, to Plateau Tibetan pig, copy number of mtDNA between spleen and lung, brain and myocardium, kidney and brain have not significant difference (p> 0.05), and other tissues have significant difference (p< 0.01). To Lowland Tibetan pig, copy number of mtDNA between spleen and lung, kidney and Psoas major muscle have not significant difference (p> 0.05), while other tissues have significant difference (p< 0.01). Copy number of mtDNA in Plateau Tibetan pig is significantly higher than in Lowland Tibetan pig, especially in Psoas major muscle and kidney. Copy number of mtDNA of psoas major muscle and kidney in Plateau Tibetan pig is 4.85 and 5.7 times higher than that in Lowland Tibetan pig, respectively. It shows that the growth and development situation and energy requirement of tibetan pig can change with the change of living environment. Among these tissues, Psoas major musclehas the biggest variation, while myocardium has the least variation. It shows that the copy number of mtDNA in myocardium is stabilized either in plateau or lowland. While the degree of variation between different tissues is bigger than different regions. In Plateau Tibetan pig, the copy number of mtDNA in lung is significantly lower than other tissues. And it is different with our traditional cognition. It shows that Tibetan pigs living in Plateau for generations have formed a unique energy metabolism system. We need to do further study from various aspects, such as more physiological and biochemical indexes, mitochondrial ultrastructure, efficiency of energy metabolism and the expression of nucleus genes.