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The gut microbiome was involved in a variety of physiological processes and played a key role in host environmental adaptation. However, the mechanisms of their response to altitudinal environmental changes remain unclear. In this study, we used 16S rRNA sequencing and LC-MS metabolomics to investigate the changes in the gut microbiome and metabolism of the Yarkand toad-headed agama (Phrynocephalus axillaris) at different altitudes (−80 m to 2000 m). The results demonstrated that Firmicutes, Bacteroidetes, and Proteobacteria were the dominant phylum, Lachnospiraceae and Oscillospiraceae were the most abundant family, and the low-altitude populations had higher richness than high-altitude populations; Akkermansiaceae appeared to be enriched in high-altitude populations and the relative abundance tended to increase with altitude. The gut microbiome of three populations of P. axillaris at different altitudes was clustered into two different enterotypes, low-altitude populations and high-altitude populations shared an enterotype dominated by Akkermansia, Kineothrix, Phocaeicola; intermediate-altitude populations had an enterotype dominated by Mesorhizobium, Bradyrhizobium. Metabolites involved in amino acid and lipid metabolism differed significantly at different altitudes. The above results suggest that gut microbiome plasticity drives the extensive adaptation of P. axillaris to multi-stress caused by different altitudes. With global warming, recognizing the adaptive capacity of wide-ranging species to altitude can help plan future conservation strategies.

Abstract In this paper, a comparative study was conducted on the extraction effects of six agents for collagen-based mural painting binders. These agents were used to extract the residual proteins in the non-aged and thermal aged samples. The protein extraction efficiencies of different extracting agents were quantitatively determined by bicinchoninic acid (BCA) method, and then processed by multivariate analysis of variance (MANOVA). The impact of the extraction process on the protein structure was characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), ultraviolet absorption spectrum (UV) and circular dichroism (CD). The results showed that, for both non-aged and aged samples, the extraction efficiency of 2 M guanidine hydrochloride (GuHCl) was significantly higher than the other five agents, with less damage to the protein structure during the extraction process.