Metabolomics And Phenotypic Differentiation Of Eothenomys Miletus In Different Areas Of Hengduan Mountains

The physiological accommodation of weight and energy metabolism is the major strategy for small mammals to cope with environmental change,body composition and digestive phenotypic plasticity are adaptive characteristics of individual animals.Leptin plays an important role in regulating the energy budget,weight,and fat content of seasonal mammals.Leptin regulates the expression of hypothalamic neuropeptides NPY,AgRP,POMC,and CART genes to adjust energy intake,the content of NPY affect body weight balance and energy homeostasis.Metabolomics aims to detect,identify and quantify all metabolites in biological samples.The study of metabolomics can reflect plastic response of organism to environmental adaptation.Metabolomics measures the multi-parameter metabolic response of living systems quantitatively by monitoring the changes of hundreds of low-molecular weight metabolites simultaneously,which can be used to assess the difference of metabolites.The morphological changes of skull and molar are closely related to the environment.The change of living environment may cause sort of changes in its morphology.Geometric morphology measurement technique(Geometric morphometric techniques)is widely used,which is a series of analytical method for statistic and can be used to reflect the environmental factors effect on the phenotypic traits of species and the species classification,etc.Geometric morphology measurement technique is mainly used to analyze the geometric shape and change of shape about object and separate the change of shape and size of the sample tested in order to enhance the reliability of the result,what's more,which can also proceed to quantitative analysis on morphology of organisms and organs.Geometric morphometric techniques are widely used to measure the bone of fish,bird and animals abroad.Hengduan Mountains region is one of the biodiversity hotspots,the mountain presents a north-south trend and the climate is diverse.In this study,5 sites of Hengduan Mountains were selected as the sampling sites,which were Deqin,Xianggelila,Lijiang,Jianchuan and Ailao Mountain from north to south,to explore adaptive mechanism of Eothenomys miletus for the different regions and environments around Hengduan Mountains.This paper mainly includes three parts:(1)Analysis of thermogenic characteristics and physiological indexes of E.miletus in different locationsThe pyretogenic characteristics,food intake,weight,fresh weight of heart,lung,liver,spleen and kidney,weight and length of stomach,small intestine,large intestine and cecum,leptin content and hypothalamic neuropeptide expression about E.miletus in the different regions were measured and compared.The experimental results showed that the weight of E.miletus in the five different regions was significantly different(F=3.895,P<0.05),the weight of E.miletus was from light to heavy,followed by Deqin,Xianggelila,Lijiang,Jianchuan and Ailao Mountain.There was a significant difference in liver fresh weight(F=3.895,P<0.05),the liver fresh weight of E.miletus from Deqin was significantly heavier than that of E.miletus from Ailao Mountains.The gastric length of E.miletus in 5 different regions was also obviously different(F=3.04,P<0.05),the gastric length of E.miletus from Ailao Mountains is a little bit longer.There were significant regional differences in RMR,food intake and NPY expression of hypothalamic neuropeptide gene in E.miletus,but no significant differences in NST and serum leptin levels.The liver fresh weight and individual indexes of E.miletus from Ailao Mountain were remarkably different from those in other regions.The above results indicated that the changes of weight,liver fresh weight,and digestive tract morphology of E.miletus from five sites may be related to the change of environmental factors gradually in the area.And the results also indicated that the E.miletus living in different regions of Hengduan Mountain mainly adapted to different climatic and environmental conditions by changing their weight,weight of organ and digestive tract,and morphology,thermogenic characteristics and food intake,etc.In addition,hypothalamic neuropeptide NPY may be involved in the thermogenic accommodation.(2)Analysis of serum and liver metabolomics of E.miletus in different sitesThe changes of serum and liver metabolomics were measured and compared by GC-MS.Results: 88 and 86 metabolites were detected in serum and liver respectively.Liver metabolite PCA analysis,serum and liver metabolites PLS-DA and overall sample tree-like graph showed that Deqin and Xianggelila E.miletus samples were clustered together,while Lijiang,Jianchuan and Ailao Mountains samples got together.The bidirectional clustering heat map showed that the concentration of lipid and amino acid metabolites in the serum of E.miletus from Deqin and Xianggelila were obviouly higher than that of E.miletus from other three sites.The concentrations of tricarboxylic acid cycle intermediates,fat metabolites and amino acid metabolites in the liver of E.miletus from Deqin and Xianggelila were remarkably higher,while the concentrations of glycolysis metabolites of E.miletus from Deqin and Xianggelila were significantly lower.The analysis of differential metabolic pathways showed that the activity of lipid metabolism and amino acid metabolism pathways in serum,tricarboxylic acid circulation,lipid metabolism and amino acid metabolism pathways in liver of E.miletus in Deqin and Xianggelila areas were significantly higher.Activity of Liver glycolysis metabolic pathway of E.miletus was remarkably lower in Deqin and Xianggelila.The results showed that the E.miletus living in different places in this region adapted to different environmental temperatures and altitudes in Hengduan Mountain by adjusting the concentration of serum and liver metabolites and the activity of metabolic pathways.(3)Geometric and morphological analysis of the skull of E.miletus in different sitesThe deformations of dorsal,ventral and lateral mandible,upper molars and lower molars were studied by geometric morphometry.The results revealed that principal component analysis and discriminant function analysis showed that only the dorsal part of the skull of E.miletus from Ailao Mountain was separated,while other four were mixed together.The results showed that most of the morphological changes of the skull were concentrated in the nasal bone and zygomatic arch.Multidimensional analysis indicated that the skull and molars of E.miletus in five regions were different,which might be related to the changes of latitude,longitude,altitude and temperature.In conclusion,the skull morphology of E.miletus in different environments in Hengduan Mountain region is diverse so as to adapt to different environmental conditions.