Comparative analysis of the gut bacteria and fungi in migratory demoiselle cranes (Grus virgo) and common cranes (Grus grus) in the Yellow River Wetland, China.

Introduction: Gut microbiota are closely related to the nutrition, immunity, and metabolism of the host and play important roles in maintaining the normal physiological activities of animals. Cranes are important protected avian species in China, and they are sensitive to changes in the ecological environment and are thus good environmental indicators. There have been no reports examining gut fungi or the correlation between bacteria and fungi in wild Demoiselle cranes (Grus virgo) and Common cranes (Grus grus). Related research can provide a foundation for the protection of rare wild animals. Methods: 16S rRNA and ITS high-throughput sequencing techniques were used to analyze the gut bacterial and fungal diversity of Common and Demoiselle cranes migrating to the Yellow River wetland in Inner Mongolia. Results: The results revealed that for gut bacteria α diversity, Chao1 index in Demoiselle cranes was remarkably higher than that in Common cranes (411.07 ± 79.54 vs. 294.92 ± 22.38), while other index had no remarkably differences. There was no remarkable difference in fungal diversity. There were marked differences in the gut microbial composition between the two crane species. At the phylum level, the highest abundance of bacteria in the Common crane and Demoiselle crane samples was Firmicutes, accounting for 87.84% and 74.29%, respectively. The highest abundance of fungi in the guts of the Common and Demoiselle cranes was Ascomycota, accounting for 69.42% and 57.63%, respectively. At the genus level, the most abundant bacterial genus in the Common crane sample was Turicibacter (38.60%), and the most abundant bacterial genus in the Demoiselle crane sample was Catelicoccus (39.18%). The most abundant fungi in the Common crane sample was Penicillium (6.97%), and the most abundant fungi in the Demoiselle crane sample was Saccharomyces (8.59%). Correlation analysis indicated that there was a significant correlation between gut bacteria and fungi. Discussion: This study provided a research basis for the protection of cranes. Indeed, a better understanding of the gut microbiota is very important for the conservation and management of wild birds, as it not only helps us to understand their life history and related mechanisms, but also can hinder the spread of pathogenic microorganisms.

Comparative analysis of the gut bacteria of the relict gull (Larus Relictus) and black-necked grebe (Podiceps Nigricollis) in Erdos Relic Gull National Nature Reserve in Inner Mongolia, China.

The gut microbiota promotes host health by maintaining homeostasis and enhancing digestive efficiency. The gut microflora in wild birds affects host physiological characteristics, nutritional status, and stress response. The relict gull (Larus Relictus, a Chinese national first-class protected species) and the black-necked grebe (Podiceps Nigricollis, a secondary protected species) bred in the Ordos Relic Gull National Nature Reserve share similar feeding habits and living environments but are distantly related genetically. To explore the composition and differences in the gut microbiota of these two key protected avian species in Erdos Relic Gull National Nature Reserve and provide a basis for their protection, 16S rRNA gene high-throughput sequencing was performed and the gut microbial diversity and composition of the relict gull (L. Relictus) and black-necked grebe (P. Nigricollis) was characterized. In total, 445 OTUs (operational taxonomic units) were identified and classified into 15 phyla, 22 classes, 64 orders, 126 families, and 249 genera. Alpha diversity analysis indicates that the gut microbial richness of the relict gull is significantly lower than that of the black-necked grebe. Gut microbe composition differs significantly between the two species. The most abundant bacterial phyla in these samples were Proteobacteria, Firmicutes, Fusobacteria, and Bacteroidetes. The prominent phylum in the relict gull was Proteobacteria, whereas the prominent phylum in the black-necked grebe was Firmicutes. The average relative abundance of the 17 genera identified was greater than 1%. The dominant genus in the relict gull was Escherichia-Shigella, whereas Halomonas was dominant in the black-necked grebe. Microbial functional analyses indicate that environmental factors exert a greater impact on relict gulls than on black-necked grebes. Compared with the relict gull, the black-necked grebe was able to use food more efficiently to accumulate its nutrient requirements, and the gut of the relict gull harbored more pathogenic bacteria, which may be one reason for the decline in the relict gull population, rendering it an endangered species. This analysis of the gut microbial composition of these two wild avian species in the same breeding grounds is of great significance, offers important guidance for the protection of these two birds, especially relict gulls, and provides a basis for understanding the propagation of related diseases.

[Mstn knockdown promotes intramuscular fatty acid metabolism by ß oxidation via the up-regulation of Cpt1b].

Myostatin (Mstn) is known as growth/differentiation factor-8 (GDF-8). Knockout or knockdown of Mstn gene promotes muscle development and reduces fat content. Here we prepared Mstn knockdown mice by RNA interference, then the morphology of the skeletal muscle, the content of triglyceride (TG), the content and composition of fatty acids in the skeletal muscle were detected. The expression of Mstn reduced in muscle of Mstn knockdown mice compared to the controls. The cross sectional areas of the skeletal muscle myofibers were significantly larger while the content of TG was less than that of the controls, and the ratios of n-3/n-6 and unsat/sat in the knockdown mice increased significantly. Subsequently, we detected the expression of genes associated with fatty acid metabolism. The expression of the genes associated with lipolysis and fatty acid transportation were up-regulated, while the genes associated with fatty acid synthesis were down-regulated. Of these genes, the up-regulation of a gene associated with ß oxidation, Cpt1b, was up-regulated remarkably. We further detected the enzyme activity of CPT1 in skeletal muscle and obtained the same results with gene expression. Moreover, chromatin immunoprecipitation assay was performed and we found that SMAD3, a transcription factor downstream of Mstn, directly binds to the promoter of Cpt1b gene. These results showed that knockdown of Mstn up-regulated the expression of Cpt1b through the binding of SMAD3 to the promoter of Cpt1b, then promoted the ß oxidation metabolism of intramuscular fatty acids.