Single-cell transcriptomes from turtle livers reveal sensitivity of hepatic immune cells to bacteria-infection.

The liver is important in the synthesis, metabolism and storage of nutrients, detoxification and immune response of the body, and the liver immune response against exogenous pathogens from the intestinal tract plays a key role in the immune activities. However, the cellular composition of the liver immune atlas remains sparsely studied in reptiles. We used single-cell RNA sequencing to identify the cellular profile of the liver of the Chinese soft-shelled turtle (Pelodiscus sinensis). We obtained the transcriptional landscape based on 9938 cells from the fractionation of fresh hepatic tissues from two individuals, uninfected and infected with bacteria (Aeromonas hydrophila). We identified seven hepatic immune cell subsets, including plasma, erythroid, T/NK, B, endothelial, dendritic and Kupffer cells. Bacteria-infection altered the number of liver immune cells, as revealed by the fact that the infected turtle had more plasma, endothelial and Kupffer cells and fewer T/NK, dendritic and erythroid cells than did the uninfected turtle. Our study is the first to provide a comprehensive view of the hepatic immune landscape of P. sinensis at the single-cell resolution that outlines the characteristics of immune cells in the turtle liver and provides a liver transcriptome baseline for turtle immunology.

Captivity affects diversity, abundance, and functional pathways of gut microbiota in the northern grass lizard Takydromus septentrionalis.

Animals in captivity undergo a range of environmental changes from wild animals. An increasing number of studies show that captivity significantly affects the abundance and community structure of gut microbiota. The northern grass lizard (Takydromus septentrionalis) is an extensively studied lacertid lizard and has a distributional range covering the central and southeastern parts of China. Nonetheless, little is known about the gut microbiota of this species, which may play a certain role in nutrient and energy metabolism as well as immune homeostasis. Here, we examined the differences in the gut microbiota between two groups (wild and captive) of lizards through 16S rRNA sequencing using the Illumina HiSeq platform. The results demonstrated that the dominant microbial components in both groups consisted of Proteobacteria, Firmicutes, and Tenericutes. The two groups did not differ in the abundance of these three phyla. Citrobacter was the most dominant genus in wild lizards, while Morganella was the most dominant genus in captive lizards. Moreover, gene function predictions showed that genes at the KEGG pathway levels2 were more abundant in wild lizards than in captive lizards but, at the KEGG pathway levels1, the differences in gene abundances between wild and captive lizards were not significant. In summary, captivity exerted a significant impact on the gut microbial community structure and diversity in T. septentrionalis, and future work could usefully investigate the causes of these changes using a comparative approach.