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Silver pomfret (Pampus argenteus) performs a significant appetite for jellyfish, and amino acids are common components of the natural prey of fish, so we investigated the effect of aspartic acid, glycine and cysteine (high‐content amino acid in jellyfish) on olfactory‐related receptors regulating appetite in silver pomfret. The fish showed significant attractant responses to these amino acids in water, which were also observed to improve the ingestion rates of the fish. Next, we conducted transcriptomes of the olfactory epithelium (OE) and identified 34 olfactory‐related receptor genes were including olfactory receptors, trace amine‐associated receptors and vomeronasal receptors genes, and we examined these genes in the OE and appetite‐related genes (ghrelin and leptin in gut/stomach and neuropeptide Y, agouti‐related protein and proopiomelanocortin in brain) by qRT‐PCR. The olfactory‐related receptor genes significantly expressed in amino acid groups, and the expression level of appetite‐related genes was highest in aspartic acid group. Thus, olfactory‐related receptors induced by amino acids might regulate appetite in fish through the OE–brain–gut and stomach axis. Using these data, we identified some effective amino acid phagostimulants which could be supplied in silver pomfret diet, and the results improved our understanding of the mechanism of olfactory‐related receptors regulating appetite in fish. [ABSTRACT FROM AUTHOR]

Hepatic lipase (HL) is a key enzyme in endogenous triglyceride metabolism in blood circulation. The molecular mechanism and function of Pampus argenteusHL gene was investigated by cloning the full‐length cDNA of HL using PCR and RACE. The temporal and spatial expression characteristics of HL in different tissues and growth stages of P. argenteus and its localization in the liver were examined using real‐time PCR and in situ hybridization, and liver crude fat content was determined. The full‐length cDNA of P. argenteusHL gene was 1836 bp (GenBank No. KU497716); the 1485 bp ORF encodes 494 amino acids. P. argenteus HL protein had the highest homology with Siniperca chuatsi HL protein. In P. argenteus, HL was highly expressed in the liver and scarcely expressed in other tissues. HL expression in P. argenteus initially increased and then decreased at different growth stages (1–5, 5–15, 15–30, 30–50, 50–100 and >100 g), with the highest expression at 30–50 g fish weight, which was positively correlated with liver fat content. In situ hybridization showed that, in liver cells, HL was highly and weakly expressed in the cytoplasm and nucleolus, respectively, and not expressed in the nuclear interstitium. [ABSTRACT FROM AUTHOR]

Gut microorganisms play an important role in host health and have susceptibility to diseases, undergoing a distinct transformation at early stages of development. This study aimed to determine the regulation of gut microorganism development from fertilized eggs to 150 DAH (days after hatching) and the differences between flatulent and healthy silver pomfret (Pampus argenteus). High‐throughput sequencing was used to analyze the diversity and relative abundance of microorganisms. PICRUSt was used to predict functional alterations of dominant microorganisms. The results showed that from all 42 samples, a total of 3,746,895 reads were obtained, representing 6,081 operational taxonomic units (OTUs). Top 3 phyla were Proteobacteria, Firmicutes and Bacteroidetes. From 0 to 32 DAH, the relative abundance of Proteobacteria continuously increased and peaked at 94.99%. After that, the abundance of Proteobacteria decreased, but Bacteroidetes and Firmicutes increased instead. Alpha diversity is the lowest at 32 DAH, the difference is significant compared with others, p <.05. Comparing flatulent fish with healthy fish, the former has more specific OTUs, higher diversity and abundance. There were four genera Ethanoligenens, Methanobacterium, Caproiciproducens and Leptolinea that only obtained from the flatulent samples, but almost none in the healthy samples. All of these four genera are directly or indirectly involved in gas metabolism. This study enriched the basic research of silver pomfret, for the first time, focused on flatulent individuals which would provide a theoretical basis for the subsequent breeding. [ABSTRACT FROM AUTHOR]