Simple SummaryPiglet diarrhea is the most common type of disease on many large-scale pig farms, where it causes serious economic losses. Abuses of vaccines and veterinary medicine are very common, which not only lead to the emergence and prevalence of drug-resistant bacteria, but also to a decline in the quality of livestock products and economic benefits. Therefore, improving the resistance of piglets to diarrhea by genetic means is a common goal of modern breeding scientists. This study aims to reveal the molecular mechanism of regulating piglet diarrhea via the important candidate gene TLR5 from the perspective of epigenetic factors.AbstractToll-like receptor 5 (TLR5) plays an important role in immune system. In this study, we performed transcriptome analysis of the duodenum in E. coli F18-resistant and -sensitive Sutai weaned piglets and analyzed the differential expression of TLR5. The cellular localization of TLR5 was investigated, and the effect of TLR5 expression on E. coli invasion was evaluated after pig small intestinal epithelial cell lines (IPEC-J2) were stimulated by E. coli. The results showed that TLR5 expression level in duodenum and jejunum were significantly higher in E. coli F18-sensitive than in E. coli F18-resistant piglets. TLR5 protein was mainly expressed in the cytoplasm and cell membrane. The expression of genes associated with the TLR5 signaling pathway were significantly higher in TLR5-overexpressed cells than in control cells. Bacterial adhesion was higher in TLR5-overexpressed cells than in blank cells and lower in TLR5 interference than in blank cells. The core promoter region of TLR5 included two CpG islands and 16 acting elements. The methylation of the mC-6 site in the second CpG island of the promoter region had a regulatory effect on TLR5 expression. Therefore, TLR5 plays an important regulatory role on E. coli invasion. Low expression of TLR5 inhibited the immune response and decreased cell damage, which was conducive to the resistance to E. coli stimulation. In conclusion, this study preliminarily revealed the molecular mechanism of TLR5 gene regulating the resistance of piglets to Escherichia coli, and provided a new candidate gene for screening Escherichia coli resistance markers in pigs.

The FUT2 gene was considered as an important candidate for pathogenic infections, while the potential associations between this gene and the production and reproductive traits of pigs have not been explored. In this study, we detected the genetic variants of porcine FUT2 gene and analyzed the associations of the polymorphisms with FUT2 mRNA expression and production and reproductive traits (age at 100 kg, backfat thickness at 100 kg, eye muscle thickness, the number of newborn piglets, the number of weaned piglets, and birth weight) in 100 Large White sows. One single nucleotide polymorphism (SNP) (rs345476947, C→T) in the intron of FUT2 and three genotypes (TT, CT and CC) were determined. Association analysis revealed significant associations between this SNP with the number of newborn piglets and weaned piglets. Furthermore, individuals with the TT genotype had significantly higher numbers of newborn piglets and weaned piglets than those with the CC genotype (P < 0.05). Quantitative PCR analysis showed that FUT2 expression in individuals with CC genotype was significantly higher than those with TT and CT genotypes in the liver and lymph gland (P < 0.05) and higher than that of CT in the spleen, kidney, and duodenum (P < 0.05). These findings indicated that the TT genotype may be a favorable genotype for the reproductive traits of pigs. Our study revealed the genetic variants of the FUT2 gene and identified a promising candidate SNP (rs345476947) associated with the reproductive traits, which has the potential to be applied in selective breeding of pigs.

The Acer L. (Sapindaceae) is one of the most diverse and widespread genera in the Northern Hemisphere. Section Platanoidea harbours high genetic and morphological diversity and shows the phylogenetic conflict between A. catalpifolium and A. amplum. Chloroplast (cp) genome sequencing is efficient for the enhancement of the understanding of phylogenetic relationships and taxonomic revision. Here, we report complete cp genomes of five species of Acer sect. Platanoidea. The length of Acer sect. Platanoidea cp genomes ranged from 156,262 bp to 157,349 bp and detected the structural variation in the inverted repeats (IRs) boundaries. By conducting a sliding window analysis, we found that five relatively high variable regions (trnH-psbA, psbN-trnD, psaA-ycf3, petA-psbJ and ndhA intron) had a high potential for developing effective genetic markers. Moreover, with an addition of eight plastomes collected from GenBank, we displayed a robust phylogenetic tree of the Acer sect. Platanoidea, with high resolutions for nearly all identified nodes, suggests a promising opportunity to resolve infrasectional relationships of the most species-rich section Platanoidea of Acer.

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Escherichia coli F18 is a common conditional pathogen that is associated with a variety of infections in humans and animals. LncRNAs have emerged as critical players in pathogen infection, but their role in the resistance of the host to bacterial diarrhea remains unknown. Here, we used piglets as animal model and identified an antisense lncRNA termed FUT3-AS1 as a host regulator related to E. coli F18 infection by RNA sequencing. Downregulation of FUT3-AS1 expression contributed to the enhancement of E. coli F18 resistance in IPEC-J2 cells. FUT3-AS1 knockdown reduced FUT3 expression via decreasing the H4K16ac level of FUT3 promoter. Besides, the FUT3-AS1/miR-212 axis could act as a competing endogenous RNA to regulate FUT3 expression. Functional analysis demonstrated that target FUT3 plays a vital role in the resistance of IPEC-J2 cells to E. coli F18 invasion. A Fut3-knockout mice model was established and Fut3-knockout mice obviously improved the ability of resistance to bacterial diarrhea. Interestingly, FUT3 could enhance E. coli F18 susceptibility by activating glycosphingolipid biosynthesis and toll-like receptor signaling which are related to receptor formation and immune response, respectively. In summary, we have identified a novel biomarker FUT3-AS1 that modulates E. coli F18 susceptibility via histone H4 modifications or miR-212/FUT3 axis, which will provide theoretical guidance to develop novel strategies for combating bacterial diarrhea in piglets.