Small RNA duodenal libraries were constructed for Escherichia coli F18-sensitive and -resistant weaned piglets in full-sib pair groups and sequenced using Illumina Solexa high-throughput sequencing technology. The identification of differentially expressed miRNAs provides the basis for improved database information on pig miRNAs, understanding the genetic basics of differences in resistance to E. coli F18 between local Chinese and exotic pig breeds, and finding new resistance markers for E. coli F18 infection. The duodenum of all individuals contained more than 90% of known swine miRNAs. A total of 58 differentially expressing miRNAs were identified, of which 46 were increased and 12 were decreased in E. coli F18-sensitive pigs. Of miRNAs with increased expression, ssc-miR-143 was most highly expressed, followed by ssc-let-7f, ssc-miR-192, and ssc-miR-21. We identified a total of 2036 intersection target genes by comparing TargetScan data and previous gene expression profile results. Gene ontology and pathway analysis of intersection genes showed that differentially expressed miRNAs were mainly involved in the immune response and transcriptional regulation. Combining information on differential miRNA expression and their regulatory relationships with transcription factors, identified 12 candidate miRNA disease markers, including 11 miRNAs with increased expression, ssc-miR-143, ssc-let-7f, ssc-miR-30e, ssc-miR-148a, ssc-miR-148b, ssc-miR-181a, ssc-miR-192, ssc-miR-27b, ssc-miR-15b, ssc-miR-21, and ssc-miR-215, and one with decreased expression, ssc-miR-152. Quantitative real-time PCR analysis of candidate miRNA expression in a larger cohort of E coli F18-sensitive and -resistant animals confirmed the high-throughput sequencing results.
ABSTRACT. We compared and analyzed expression of the BPI gene of Sutai piglets ranging from newborn to post-weaning days 8, 18, 30, and 35 by the real-time PCR method, in order to determine if it is involved in protection against disease caused by ETEC F18. There was a significant difference between 18-and 35-day expression in the jejunum. There were also significant differences between 35-day expression and expression at the other development stages in the duodenum. There were no significant differences in expression at 8, 18, and 30 days in the jejunum. We conclude that the porcine BPI gene may be the direct factor that caused resistance to ETEC F18 in weaning piglets, and that the resistance to ETEC F18 in weaning piglets is related to upregulation of mRNA expression of the BPI gene to a certain extent.
ABSTRACT. TLR4 is the main recognition receptor of bacterial lipopolysaccharides, which play an important role in innate and adaptive immunity. We used real-time PCR to analyze the tissue expression profile and differential expression of TLR4 in 4 pig populations (Escherichia coli F18-resistant Sutai, E. coli F18-sensitive Sutai, Large White, Meishan), in order to determine the role that the TLR4 gene plays in resistance to E. coli F18. We found that TLR4 expressed consistently in the 4 populations, with relatively high levels in immune tissues and the highest level in the lung. Generally, the expression of TLR4 in E. coli F18-sensitive individuals was the highest, followed by that in E. coli F18-resistant, Large White and Meishan. In the spleen, lung, kidney, lymph nodes, and thymus gland, TLR4 expression is significantly higher in the E. coli F18-sensitive than in the other 3 populations; there were no significant differences among E. coli F18-resistant Sutai, Large White, and Meishan. In addition, Gene Ontology and pathway analysis showed that TLR4 takes part in the inflammatory response. We found that porcine TLR4 has consistent tissue specificity in each breed, and downregulation of expression of the TLR4 gene is related to resistance to E. coli F18 in weaning piglets.
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