Relationship Between β-globin And The Adaptation Of High Altitude Hypoxia Of Tibet Pig

Tibet pig (TB) is the only one pig breed of Plateau type in China, they mainly distribute in cold and hypoxic area with altitude of 2500 to 4300 meters, where the oxygen content in the air is only 1/3~1/2 of that at sea level. Because of natural selection and evolution, many pure genetic resources, which made TB have the adaptation of high altitude hypoxia, have remained in TB. Both the number and size of TB, however, have decreased dramatically in recent years because their performance is much lower than those of the commercial breeds of European and American origins, especially in the aspects of growth rate, food conversion efficiency and lean meat percent. This article will study the genetic mechanism of high altitude hypoxia adaptation of TB from the perspective of molecular biology, it's very important for not only protecting and utilizing the TB's genetic resource but also studying the mechanism of hypoxic-ischemic damage.Hemoglobin play a very important physiological role in binding, saving, transporting and releasing the oxygen in the body. It has been to one important part of the field of the adaptation of high altitude hypoxia that studying the hemoglobin's structure, function and other aspects. With the development of life sciences and biology technology, more and more research focused on their coding genes with the method of molecular biology.β-globin gene is one of the subunits which encoding hemoglobin, we will conduct our experiment as follows:First, In order to study the function mechanism ofβ-globin in the adapation of altitude hypoxia of Tibet pig, theirβ-globin were amplified by primers designed from pig'sβ-globin recorded in Genebank, with the control group of five Chinese pig breeds, such as Min (M), Laiwu Black (LB), Yangxin (YX), Wuzhishan (WZ) and Exi Black (EB). The cloning and sequencing results indicate that amino acid sequence of Tibet pig was different from the other five breeds, the difference was in 58th, 75th and 137th site. They are list in detail as follow: TB1's 119th site, 137th site was from Asparagine, Alanine to Histidine, Valine; TB2's 58th site, 75th site, 137th site was from Threonine, Asparagine, Alanine to Serine, Glutamate and Valine respectively; TB3'difference was in 58th and 119th site, TB4's difference was in 75th, 119th and 137th site. The difference was not be found in other five breeds.We speculate that the Valine in 137th site of Tibet pig was the possible causation of their adaptation of altitude hypoxia.Second, In order to study the correlation between microsatellite polymorphism ofβ-globin locus and the adaptation of altitude hypoxia in Tibet pig breed, studies on the microsatellite polymorphism ofβ-globin locus of TB and other five Chinese indigenous pig breeds were undertaken. The results show that in TB, there were 3 predominant alleles (frequency was more than 10%). They were 180bp, 182bp and 192bp, with proportions of 19.05%, 11.92% and 30.93% respectively. The unique common predominant allele in the six populations was 192bp. The proportions of 184bp, 186bp, 192bp and 200bp of TB were significantly different (P was less than 0.01) from the other five populations. The genotype of 192/174, 178/174, 182/174 and 212/192 were not found in TB, and the value of 200/180 , 192/180, 192/184 and 186/182 in TB were different from that in the other five breeds and the difference was significant. The polymorphicβ-globin locus shows its possible natural selective value in the adaptation to high altitude hypoxia of TB and perhaps its possible regulatory role in the synthesis of hemoglobin (HG). The results provide basic molecular data for the research on the germplasm characteristics of TB and scientific basis for the conservation and utilization of TB.Third, with the control group of for Chinese pig breeds, such as LB, YX, WZ and EB, TB's relative expression value ofβ-globin was tested on the method of FQ RT-PCR. Experiment data was analyzed by delta-delta Ct method, TB's relative expression value was much more than that of other breeds, so, we may speculate that increasing the number of red blood cell was not the only mechanism for TB's adaptation of high altitude hypoxia,β-globin also play a very important role on the level of gene expression.Studying the difference of gene expression value of altitude native animals is highly significant for our understanding of the life sciences, it may not only provide important information for studying the biological mechanisms of adaptation of high altitude hypoxia, but also give clues for the research of saving and utilizing the altitude native animals.