Salmonella infections can lead to intestinal inflammation and metabolic disorders in birds. However, whether ARA metabolism is involved in Salmonella-induced intestinal inflammation remains unclear. This experiment investigated the changes in cecal flora and arachidonic acid (ARA) metabolism in Hainan Wenchang chickens infected with S. Typhimurium using 16s rDNA sequencing and targeted metabolomics. The results showed that the levels of ARA metabolites were increased in the cecum tissue of Wenchang chickens after infection with S. Typhimurium, including prostaglandin E2, prostaglandin F2α, lipoxin A4, ±8(9)-EET, ±11(12)-EET, and ±8,9-DiHETrE. The content of key enzymes for ARA production and metabolism (PLA2 and COX-2) in chicken cecum tissues was increased after S. Typhimurium infection. The relative mRNA levels of inflammatory factors were also increased after infection, including IFN-γ, TGF-β1, IL-4, and IL-6. In HD11 cells, the use of a cyclooxygenase (COX) inhibitor reduced the increased levels of COX-2 and PGF2α induced by S. Typhimurium infection and effectively reduced the inflammatory response. In addition, the number of beneficial genera (e.g., Bifidobacterium, Lactobacillus, and Odorobacterium) in the cecum of Wenchang chickens was significantly reduced after infection with S. Typhimurium. In this study, we revealed the structure of the cecal flora of Wenchang chickens infected with S. Typhimurium and demonstrated that S. Typhimurium can mediate the onset and development of intestinal inflammation through the activation of the metabolic pathway of ARA cyclooxygenase in Wenchang chickens. The results can provide data support and theoretical support for the prevention and control of avian salmonellosis.

In mammals, fatty acid transport protein 1 (FATP1) is involved in cellular long-chain fatty acid (LCFA) uptake and activation, especially in processes of transportation, oxidation and triglyceride synthesis. However, the role of Fatp1 in invertebrates, especially decapod crustaceans, is still poorly understood. In this study, the cDNA of a fatp1 gene of a decapod crustacean, mud crab Scylla paramamosain, was cloned and functionally characterized. The fatp1 gene encoded a polypeptide of 643 amino acids that possessed all the typical features of the Fatp family, and shared high homology with the other Fatp orthologs of crustaceans. The relative expression levels of fatp1 were higher in metabolically active tissues such as hepatopancreas, stomach and gill than the other parts of crabs. Knockdown of the fatp1 gene in vivo reduced triglyceride and total lipid levels in the hepatopancreas, and increased the tissue expression levels of genes related to fatty acid transportation, allocation and hydrolysis including long-chain acyl-CoA synthetase 3/4 (acsl3/4) and carnitine palmitoyl transferase 1 (cpt1), and decreased expression levels of genes related to fatty acid synthesis such as acetyl-CoA carboxylase (acc) and fatty acid synthase (fas). Increased dietary n-3 LC-PUFA levels resulted in the up-regulation of fatp1 gene expression in the hepatopancreas, and the increase in LC-PUFA content, especially EPA and DHA, in both polar and nonpolar lipids in hepatopancreas and muscles of crabs. The data collectively suggested that the fatp1 gene, identified in S. paramamosain, might play important roles in regulating fatty acid absorption, utilization and allocation in crustaceans.