| Background: The Tibetan antelope (Pantholops hodgsonii) under the Qinghai-Tibetanbelongs to the Bovidae family of Artiodactyla order and Pantholops genus, and perches atan altitude of4300to5500metres with strong athletic ability and hypoxia tolerance. Of thebest animal model,it is the one to be studied to plateau hypoxia adaptation mechanisms.TheTibetan antelope is the species which is after countless generations of natural selection andremains unique to the Qinghai-Tibet Plateau native animal and forms a unique mechanismsof hypoxic adaptation. Endothelin (ET), with strong vasoconstrictor effect, is a biologicallyactive peptides secreted by vascular endothelial cells,and is initially separated out fromporcine aortic endothelial cell culture supernatant—it contains3isomeric peptides and hassome tissue specificity: ET-1,ET-2and ET-3,ET-1mRNA expression is in endothelial cells,ET-2major in the kidney expression, the ET-3mainly in nerve cells, renal tubular epithelialcells,especially ET-1has a physiological function and pathological significance of maximum;In normal,lung tissues of pulmonary vascular endothelium, alveolar epithelium, andpulmonary neuroendocrine cells all can express ET-1m RNA, and then have a synthesis ofET-1; In causing tissue ischemia, hypoxia and in vascular endothelial cells injury in manycardiovascular diseases, endothelin are involved in the process of pathogenesis, especiallyin the development of hypoxic pulmonary hypertension mechanism,it plays an importantrole:the effect of hypoxia in vascular smooth muscle cells enhances the pulmonary arterycontraction ET-1incurred. Studies have found that: as unique and native mammals to theQinghai-Tibet Plateau,Tibetan antelope, all the year round living in hypoxic regions at analtitude of4500meters above the alpine, is to60kilometers an hour of continuous running70-100km, but the pulmonary arterial pressure is lower than the same elevation species.Aim: In order to reveal the hypoxic adaptation mechanisms about the passivation function inTibetan antelope pulmonary arterial hypertension ET-1plays in,then we clone the codingsequence of cDNA origined from Tibetan Antelope lung tissue and make a anlysis inhomology with other species.Methods and results: This topic makes a collection respectively from Hoh Xil Nationalnature reserve (4300m)in10Tibetan antelope,10Tibetan sheep and from Qing hai min he (1800m) in8Sheep in weight, hemoglobin, heart rate, pulmonary artery pressure and otherphysiological indexes to statistically analyze, then makes a use of a ELISA method tomeasure the content of serum ET-1of Tibetan antelope,Tibetan sheep and Sheep and thenextracting the total RNA from lung tissue of Tibetan antelope preserving in-80°C liquidnitrogen.Using primers for amplification of cloned ET-1gene cDNA CDS District,we use amethod of bioinformatics to analysis that the ET-1gene coding region is composed of609bpand codes202amino acids. The encoding region of ET-1gene of Tibetan antelope wasobtained and deposited in GenBank as accession number JQ031153. DNA sequencingproved that Tibetan Antelope ET-1sequence was homologous with the following speciessuch as sheep (98%),cattle (95%),pig (86%), rat (81%) and zebrafish(48%).The deducedAmino acid sequence showed97%,94%,79%,76%and34%identity when compared withthat of the sheep,cattle,pig,and rat. When comparing the ET-1Sequence of Tibetan Antelopelogined in NCBI Databank with that of sheep,six mutations can be observed at thecorresponding amino acid sequence of30and172(Thrâ†'Ala),40and163(Valâ†'Ala),141(Aspâ†'Asn),181(Pheâ†'Val), however,if these mutations are related tohypoxia passivation function of endothelin, it is subject to further study. this research hassuccessfully cloned ET-1gene encoding sequence. In this study，mutations can be observedat the corresponding amino acid sequence translated by CDS region of ET-1gene in TibetanAntelope lung tissue，and then it lays a foundations for future research in genome level.Previous studies have shown that:in the long-term evolution, the Tibetan antelope inrespiration, circulation, and other aspects form a unique adaptation to low temperature andlow oxygen environment in physiological mechanism. The study of physiological indexmeasure and analysis shows that: there was no Significant difference among the Tibetanantelope,Tibetan sheep and Sheep in weight in multiple comparison（P>0.05）; The Hbcontent, HR and MPAP values in Tibetan antelope are respectively lower than in Tibetansheep,and there are significant differences in the statistics (P＜0.01); The HR in Tibetanantelope at the same time is also less than Sheep, there is a statistically significantdifference (P＜0.01) and in Hb and MPAP, no obvious difference（P>0.05）. The results ofthis study also find: Hb and MPAP in Sheep are lower the Tibetan Sheep (P＜0.05), HR had no significant difference in two（P>0.05）. By the method of ELISA,we find: Tibetan antelopeGroup in ET-1content of serum below the Tibetan Sheep Group, there are significantdifferences statistically (P <0.01); And Sheep Group have no differences from Tibetanantelope Group in ET-1content of serum in contrast.And there are no significant differencesstatistically in Tibetan Sheep Group and Sheep Group.These results illustrate the Tibetanantelope a physiological ability in adaptation to plateau environments.Conclusion: It shows that: the Tibetan antelope may has no pumonary hypertension toadapt to hypoxia in plateau through blunted hypoxic pulmonary vasoconstrictiveresponse.Besides,The encoding region of Tibetan antelope ET-1gene is successfullycloned, and corresponding amino acids have some mutatins found comparing with Sheep byanalysis,but whether are the mutations related to pulmonary vascular hypoxic adaptation ornot? it is a further study. Therfore, all these not only lay a foudation in expression and inbiological activity,but also provide experimental basis in studying relatead gene of hypoxiaadapatation to plateau. |
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