| Gansu zokor (Myospalax cansus) is harmful subterranean rodents which lives on the loess plateau of our country. The living environment is typically low O2and high CO2. Living long term in the hypoxia underground environment, they have developed many special adaptive characters on configuration and function to adapt the special circumstances. Such as cardiovascular system improves the capability of hypoxia adaptation by improving the function of blood, enhancingcardiac reserve and myocardial contractive. The capability of taking and using oxygen is improved as well. The study found that the number of red blood cell (RBC), hemoglobin concentration(HGB) and hernatocrit(HCT) are significantly higher after hypoxia adaptation in the Gansu zokor; Compensatory response to that made by the body to fight the hypoxia stress. When there isn’t enough oxygen in the habitat, the body can increase the number of value-added of red blood cells and hemoglobin synthesis to improve the ability of blood oxygen carrier to reduce the hypoxic damage. Although studies have shown that Gansu zokors adapt to underground hypoxic environment on the physiological level, but there is no report from the researches of hemoglobin gene and the amino acid sequence features. Shams (2004) shaped mole rat (Spalax) hypoxia-inducible factor-la and erythropoietin hormone researches, showing that subterranean rodents can well adapt to the underground hypoxic life environment at the genetic level.In this study, the types of hemoglobin are firstly analyzed by polydactyl amide gel ehctrophoresis. The results show that Gansu zokors normoxia group show a2types, the same as they are placed to hypoxia positions10.5%oxygen concentration for a month. The change is not obvious. Because SD rats often feed under normal position was the four belt-shaped, when placed in the hypoxia positions10.5%oxygen concentration for one month, there appears a new type. Hypoxia and then normoxia a month later with a shape change is not large. It is showed that under different oxygen concentrations, the specific changes in SD rats can adapt to low oxygen environment to improve the body’s oxygen supply, which has some physiological significance.In this research, we compared the nucleotide sequence of the P-globin of Mus. Rattus. Deer mice and Human being. There is little difference in upstream of initiation codon and downstream of termination codon about20bp. So we designed two pairs of primer based on those parts to amplification theβ-globin of Gansu Zokor. The first pair is HBBF1and HBBR1and we got a fragment of1054bp. The second pair is HBBF2and HBBR2and we got a fragment of1073bp. After splicing, we got a fragment of1154bp. There are3exons and2intrones.146amino acids were deduced from software.We cloned and detected the Gansu Zokorsβ-globin sequences. We compared the deduced amino acid sequence of the Gansu zokors (3-chain with that of humans. Nannospalax ehrenbergi,Mus,Rattus,Deer Mice and Ochotona curzoniae.whereas only one substitution was found in theα1β2contact region (β43Gluâ†'Thr)。Only one of these exchanges is involved in the heme contacts (P70Alaâ†'Ser). two of the residues constituting theα1β1contacts in human hemoglobin are replaced (β112Cysâ†'Val and β125Proâ†'Ala), The β112is in contact with residues α107, α110and α122. The β125is in contact with residue a34. These positions locate at α1β1contact which is known to be very tight and remains largely unchanged during the quaternary conformational change that accompanies ligand binding at the heme site in normal human HbA.The amino acid sequence of Gansu zokors and the blind mole rat β chain is only10sites to change. Both blind mole rat and Gansu zokor are living in hypoxic and hypercapnic environment of the tunnel. In the process of long-term evolution and adaptation, they have developed a good mechanism to response hypoxic stress. The β-chain amino acid sequences are the most similar, and some important replacement sites of the amino acid sequences of the P-globin of Gansu zokors compared with that of human hb are basically the same as some of the important sites of the blind mole rat compared to human. According to the analysis of amino acid sequences of Gansu zokor hemoglobin β-globin and the blind mole rat β-globin protein, the molecular adaptation mechanisms on the hypoxic environment may be very similar.There are32-bit replacements of amino acid sequences between Gansu zokors and terrestrial animals plateau pika P chain. Gansu zokors and plateau pikas are mammalian to adapt to the hypoxic environment, but the difference is their living environment. The plateau pikas are the ground animals and the Gansu zokors are subterranean rodents. Gansu zokors have to adapt to both hypoxia and high carbon dioxide. Therefore, from the physiological, biochemical and metabolic levels, they both have formed their own unique mechanisms to adapt to the hypoxic environment. Some amino acids of Gansu zokors can adapt to low oxygen, especially high carbon dioxide environment more favorably. Finally, the genetic distance and phylogenetic tree analysis of Gansu zokors to other species of hemoglobinβ-chain show that Gansu zokors are most closely related to blind mole rat. Therefore, the genetic difference of β-globins of Gansu zokors may be one of the adaptive mechanisms of the hypoxia environment. |
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