Dampness-heat diarrhea (DHD), a common syndrome in Chinese dairy farms, is mainly resulted from digestive system disorders, and accompanied with metabolic disorders in some cases. However, the underlying mechanisms in the intestinal microbiome and plasma metabolome in calves with DHD remain unclear. In order to investigate the pathogenesis of DHD in calves, multi-omics techniques including the 16S rDNA gene sequencing and metabolomics were used to analyze gut microbial compositions and plasma metabolic changes in calves. The results indicated that DHD had a significant effect on the intestinal microbial compositions in calves, which was confirmed by changes in microbial population and distribution. A total of 14 genera were changed, including Escherichia-Shigella, Bacteroides, and Fournierella, in calves with DHD (P < 0.05). Functional analysis based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations indicated that 11 metabolic functions (level 2) were significantly enriched in DHD cases. The untargeted metabolomics analysis showed that 440 metabolites including bilineurin, phosphatidylcholine, and glutamate were significantly different between two groups (VIP > 1 and P < 0.05), and they were related to 67 signal pathways. Eight signal pathways including alpha-linolenic acid, linoleic acid, and glycerophospholipid metabolism were significantly enriched (P < 0.05), which may be potential biomarkers of plasma in calves with DHD. Further, 107 pairs of intestinal microbiota-plasma metabolite correlations were determined, e.g., Escherichia-Shigella was significantly associated with changes of sulfamethazine, butyrylcarnitine, and 14 other metabolites, which reflected that metabolic activity was influenced by the microbiome. These microbiota-metabolite pairs might have a relationship with DHD in calves. In conclusion, the findings revealed that DHD had effect on intestinal microbial compositions and plasma metabolome in calves, and the altered metabolic pathways and microorganisms might serve as diagnostic markers and potential therapeutic targets for DHD in calves.

The genomic context of the mcr-1 gene in Escherichia coli from animal feces has been widely reported. However, less is known about the mcr-1-carrying plasmid characteristics and other functional regions of Escherichia coli isolates from animal organs with lesions. The present study investigated the antimicrobial resistance, population structure, and genetic features of mcr-1-positive Escherichia coli strains isolated from animal organs with lesions. The antimicrobial susceptibility testing indicated that 24 mcr-1-positive Escherichia coli isolates were resistant to at least three or all antimicrobial categories. MLST analysis suggested that the dominant clone complexes (CC) were mainly CC156, CC448, and CC10. In addition, ST10596, a newly discovered sequence type in swine, failed to be classified. Meanwhile, the mcr-1 gene located on the different plasmids was successfully transferred to the recipients, and whole-genome sequencing indicated the mcr-1 gene was embedded in mcr-1-pap2 cassette but not flanked by ISApl1. The mcr-1 gene is located on the chromosome and embedded in Tn6330. Furthermore, NDM-5 was found on the IncX3-type plasmid of J-8. The virB6 and traI gene of type IV secretion system (T4SS) were truncated by IS2 and IS100 and located on the IncX4- and the IncHI2/HI2A/N-type plasmids, respectively. The multidrug-resistant (MDR) region of IncHI2/HI2A/N-type plasmids contained two class 1 integrons (In0, In640) and four composite transposons (Tn4352, Tn6010, cn_4692_IS26, cn_6354_IS26). Overall, 24 mcr-1-positive Escherichia coli isolates in our study showed MDR, or even extensively drug resistant (XDR), and exhibited population diversity. The T4SS gene truncation by the insertion sequence may affect the efficiency of plasmid conjugative transfer. Furthermore, the class 1 integrons and composite transposons in the MDR region of IncHI2/HI2A/n-type plasmid contributed to the multireplicon plasmid formation, the acquisition, and transfer of antimicrobial resistance genes (ARGs).

Spermatogenesis directly determines the reproductive capacity of male animals. With the development of society, the increasing pressure on people’s lives and changes in the living environment, male fertility is declining. The leaf of Eucommia ulmoides Oliv. (Eucommiae Folium, EF) was recorded in the 2020 Chinese Pharmacopoeia and was used in traditional Chinese medicine as a tonic. In recent years, EF has been reported to improve spermatogenesis, but the mechanisms of EF remain was poorly characterized. In this study, the effect of EF ethanol extract (EFEE) on spermatogenesis was tested in mice. Chemical components related to spermatogenesis in EF were predicted by network pharmacology. The biological activity of the predicted chemical components was measured by the proliferation of C18-4 spermatogonial stem cells (SSCs) and the testosterone secretion of TM3 leydig cells. The biological activity of chlorogenic acid (CGA), the active compound in EF, was tested in vivo. The cell cycle was analysed by flow cytometry. Testosterone secretion was detected by ELISA. RNA interference (RNAi) was used to detect the effect of key genes on cell biological activity. Western blotting, qRT–PCR and immunofluorescence staining were used to analyse the molecular mechanism of related biological activities. The results showed that EFEE and CGA could improve spermatogenesis in mice. Furthermore, the main mechanism was that CGA promoted SSC proliferation, self-renewal and Leydig cell testosterone secretion by promoting the expression of SHP2 and activating the downstream signaling pathways involved in these biological processes. This study provided strong evidence for elucidating the mechanism by which EF promotes the spermatogenesis in mice and a new theoretical basis for dealing with the decrease in male reproductive capacity.