| The high altitude environment of the Tibetan plateau poses hypothermia and hypoxic stress to plateau animals,which affect their life,physiological characteristics and reproduction.These changes in temperature,oxygen content and food composition are reflected directly in the metabolites and gut microbiota of animals.Plateau pika(Ochotona curzoniae),a small herbivorous mammal living on the Tibetan plateau,has an unclear mechanism of adapting to high altitude environments.At present,there are few metabolomic studies related to the adaptation of plateau pika to high altitude.In this study,we chose three altitude gradients,3400 m,3600 m and 3800 m above sea level as low,mid and high altitude in the alpine meadows of Haibei,Qinghai.We captured plateau pikas,collected the serum and cecum contents of pikas and used 16 S r RNA gene sequencing and T500 absolute quantitative targeted metabolome determination based on LC-QQQ-MS for metabolomics and microbiomics to search for altitude-dependent biomarkers and explore the relationship between metabolites and gut microbiota,ultimately to reveal the mechanism of altitude adaptation in plateau pika.1.Multivariate statistical analysis was used to differentiate the serum metabolite samples from three altitude groups of plateau pika,and 25,31 and 26 differential metabolites were screened between every two groups,respectively.The machine learning algorithm based on random forest was used to model the serum metabolites at different altitudes and identified five biomarkers: dihydrotestosterone,homo-Larginine,α-ketoglutaric-acid,serotonin and threonine.2.The results of principal co-ordinates analysis showed that there were significant differences in β-diversity between high-altitude and other groups.In addition,we screened 6,17,and 11 differential microbial genera and identified five microbes associated with five biomarkers: Prevotella,Lachnospiraceae＿Agathobacter and Ruminococcaceae.3.Prevotella significantly positively correlated with three biomarkers,α-ketoglutaric-acid,homo-L-arginine and threonine,in the feces and serum of plateau pika,contributing to the ability to produce heat and obtain energy at high altitudes.Lachnospiraceae＿Agathobacter significantly positively correlated with serum serotonin,and the significant decrease of serotonin at high altitude could reduce obesity and metabolic dysfunction,which may explain the decrease of body weight of plateau pika at high altitude.Ruminococcaceae significantly positively correlated with dihydrotestosterone in the plateau pika serum.The increase of dihydrotestosterone in serum metabolites would help to improve reproduction and resist the inflammatory response caused by hypoxia at high altitude. |
