Molecular Identification and Expression Analysis of an Intelectin Gene in the Yellow Catfish Pelteobagrus fulvidraco (Siluriformes: Bagridae)

Abstract

Intelectins (ITLNs) are a family of calcium-dependent lectins with carbohydrate-binding capacity, are distributed across various vertebrates, and play an important role in the innate immune response against pathogen infection. The yellow catfish Pelteobagrus fulvidraco (Siluriformes: Bagridae) is an economically important fish in China. The aim of this study was to quantify the gene expression of ITLN in response to pathogen-associated molecular patterns (PAMPs) stimulation. Here, the ITLN gene of P. fulvidraco was characterized and named PfITLN. The full-length cDNA of PfITLN was 1132 bp, including a 5’-untranslated region (UTR) of 140 bp, a 3’-UTR of 110 bp, and an open reading frame (ORF) of 882 bp encoding a polypeptide of 293 amino acids, which contains a signal peptide and two fibrinogen-related domains (FReDs). PfITLN had a molecular weight of 32.39 kDa with a theoretical pI of 5.03. The deduced PfITLN amino acid sequence had 81%, 64%, and 55% homology with Ictalurus furcatus, Danio rerio, and Homo sapiens, respectively. Moreover, the predicted tertiary protein structure of PfITLN was highly similar to that of other animals, and phylogenetic analysis showed that the PfITLN protein was close to those of other Teleostei. Real-time quantitative reverse transcription-PCR (qRT-PCR) analysis showed PfITLN expression in all examined tissues, with the highest abundance seen in the liver, followed by the head kidney, spleen, trunk kidney, and muscle. After PAMP infection with lipopolysaccharide (LPS) and polyriboinosinic polyribocytidylic acid (poly I:C), the expression levels of PfITLN were significantly upregulated at different time points. These results suggested that PfITLN might be involved in innate immunity.

Transcriptome Analysis Revealed Potential Immune-Related Genes of Head Kidney in the Yellow Catfish (Pelteobagrus fulvidraco) Challenged with Aeromonas hydrophila

“…They play a crucial role in antigen presentation and initiation of the adaptive immune response [63]. The liver, spleen, head kidney, and blood showed an upregulation in the expression of P. fulvidraco CTL following the challenge with lipopolysaccharide and polyriboinosinic polyribocytidylic acid [9]. Following Cryptocaryon irritans challenge, the head kidney and liver of Lates calcarifer experienced an induction in the mRNA transcript levels of CTL [64].…”

“…One of the most destructive pathogens, causing significant losses, is Aeromonas hydrophila, a Gram-negative bacterium, which is an oxidase-positive and facultative anaerobic. This is an opportunistic aquatic pathogen that produces various virulence factors, including hemolysins, aerolysins, adhesins, enterotoxins, phospholipase, and lipase [4], P. fulvidraco has become increasingly popular as a model fish for studying breeding technology, toxicology, immune response, and lipid metabolism in recent years [5][6][7][8][9]. However, the effect of A. hydrophila on P. fulvidraco has not been reported.…”