| Animals living in plateau environment with low atmospheric pressure,low partial oxygen pressure,low temperature and strong ultraviolet radiation are prone to cause various acute or chronic plateau diseases.Therefore,it is of great significance to study the adaptability of plateau hypoxia environment.Tibetan sheep are mainly distributed in the Qinghai-Tibet Plateau and its adjacent areas at the altitude of 3,000~5,000 meters above sea level.It is one of the special livestock species suitable for the development of alpine pastoral areas and one of the important economic sources of agriculture and animal husbandry democracy in the Qinghai-Tibet Plateau.By the end of 2016,the sheep stocks in Tibet and Qinghai alone had exceeded 22 million.Long-term life reproduction has made Tibetan sheep have a good adaptability to the cold and hypoxic environment.After long-term natural selection and artificial selection,Tibetan sheep have stable genetic characteristics in physiological,biochemical and other indicators.This makes Tibetan sheep an ideal experimental animal of high altitude hypoxia.Mitochondria,as an energy "processing factory" in eukaryotic cells,are the main sites of aerobic respiration,and play an important role in maintaining intracellular calcium homeostasis and regulating cell apoptosis.Mitochondrial fusion and division regulate the morphology of mitochondria,and the integrity of mitochondrial morphology and structure,especially the cristae structure,directly affects the function of mitochondria.At present,most of the studies on hypoxic adaptability of Tibetan sheep at high altitude are mainly focus on molecular regulation mechanism,histology,morphology,physiology and anatomy,while few studies on the specificity of the ultrastructure of mitochondria in Tibetan sheep.Therefore,in this study,Tibetan sheep and Small-tailed Han sheep were selected as the research objects.The expression of OPA1 and Mi60 genes and proteins in different tissues of Tibetan sheep were localized and quantitatively studied by using real-time fluorescence quantitative PCR,immunohistochemistry,immunoelectron microscopy and enzyme-linked immunosorbent assay.In order to reveal the physiological mechanism of Tibetan sheep adapting to high altitude hypoxic environment,the ultrastructure of mitochondria in these tissues was compared and studied,which provided theoretical basis for the adaptation mechanism of Tibetan sheep to high altitude hypoxic environment and basic data for the development of high altitude medicine.The results showed that:1.OPA1 and Mic60 genes were expressed in heart,kidney,spleen and muscle tissues of Tibetan sheep and Small-tailed Han sheep,showing obvious tissue and breed differences.The expression of OPA1 and Mic60 genes in spleen were significantly lower than that in heart,kidney and muscle.And the expression levels of OPA1 and Mic60 genes in heart,kidney,spleen and muscle of Tibetan sheep were higher than those of Small-tail Han sheep(p < 0.05).2.The expression of OPA1 and Mic60 genes had a certain effect on the number and morphology of mitochondrial cristae.Mitochondria in heart,kidney,spleen and muscle were observed under electron microscopy.They all had clear bilayer membrane and tubular cristae with complete structure.Mitochondrial bilayer membranes in myocardium and skeletal muscle were clear and cristae were dense and clear;mitochondrial bilayer membranes in kidney were clearer,cristae were relatively sparse and slightly swollen;mitochondrial cristae in spleen were the least and its structure was not clear,cristae was swollen,cristae gap was larger,cristae width was obviously larger than the width between its inner and outer membranes and was obviously larger than the width of mitochondrial cristae in other tissues(p < 0.05).The number of mitochondrial cristae in the above four tissues ofTibetan sheep was higher than that of corresponding tissues of small tail Han sheep(p < 0.05).3.Mic60 and OPA1 genes and proteins were expressed in myocardium of adult and old Tibetan sheep,and showed significant differences.In adult Tibetan sheep,the expression of Mic60,OPA1 genes and proteins were higher than that of old Tibetan sheep,and the expression of Mic60,OPA1 genes and OPA1 protein had significant difference(p < 0.05).4.The mitochondria in the myocardium of adult and old Tibetan sheep were observed under electron microscopy,which had clear bilayer membranes and tubular cristae with complete structure.The density of mitochondria in myocardium of adult Tibetan sheep was higher than that of old Tibetan sheep(p < 0.05),the number of mitochondrial cristae was higher(p < 0.05)and more dense,and the mitochondria were closely related.The mitochondrial cristae of the old Tibetan sheep was relatively sparse,the cristae membrane was wide,and the mitochondria were not closely linked,showing fragmentation.5.OPA1 protein and Mi60 protein were expressed in myocardium,liver,spleen,lung,aorta,carotid artery and pulmonary artery of Tibetan sheep.The highest expression of Mic60 protein was found in liver,followed by carotid artery,heart,aorta,pulmonary artery and lung.The expression level in spleen was the lowest.The highest expression of OPA1 protein was found in liver and lung,followed by heart,aorta,carotid artery and pulmonary artery.The expression level in spleen was the lowest.Immunoelectron microscopic results showed that OPA1 and Mic60 were located in the mitochondrial membrane.In this review,OPA1 and Mi60 proteins are mainly located on mitochondrial membrane,and their genes are widely expressed in tissues of Tibetan sheep and Small-tailed Han sheep,showing obvious tissue and breed differences,and their expression has a certain impact on the number andmorphology of mitochondrial cristae.The expression of OPA1 and Mi60 genes and proteins are higher in metabolically active tissues and organs.The expression of Mic60 and OPA1 genes and proteins in Tibetan sheep myocardium may be related to age,and aging may reduce their expression.Aging can reduce the density of mitochondria and the number of mitochondrial cristae in Tibetan sheep cardiomyocytes.Therefore,OPA1 and Mi60 are of great significance for Tibetan sheep to adapt to high altitude hypoxic environment. |
PDF Full Text Request