Molecular cloning, characterization and expression profiles of Annexin family (ANXA1~A6) in yellow catfish (Pelteobagrus fulvidraco) and ANX regulation by CpG ODN responding to bacterial infection

Selection of a suitable reference gene for gene-expression studies in Trichomonas gallinae under various biotic and abiotic stress conditions

Trichomonas gallinae, a globally distributed protozoan parasite, significantly affects the pigeon-breeding industry. T. gallinae infection mainly causes yellow ulcerative nodules on the upper respiratory tract and crop mucosa of pigeons, impeding normal breathing and feeding and ultimately causing death. Real-time quantitative PCR (qPCR) is a crucial technique for gene-expression analysis in molecular biology. Reference-gene selection for normalization is critical for ensuring this technique's accuracy. However, no systematic screening or validation of T. gallinae reference genes has been reported. This study quantified the transcript levels of ten candidate reference genes in T. gallinae isolates with different genotypes and culture conditions using qPCR. Using the geNorm, NormFinder, and BestKeeper algorithms, we assessed these reference genes' stabilities and ranked them using RankAggreg analysis. The most stable reference gene was tubulin beta chain (TUBB), while the widely used reference genes TUBG and GAPDH demonstrated poor stability. Additionally, we evaluated these candidate reference genes' stabilities using the T. gallinae TgaAtg8 gene. On using TUBB as a reference gene, TgaAtg8's expression profiles in T. gallinae isolates with different genotypes remained relatively consistent under various culture conditions. Conversely, using ACTB as a reference gene distorted the data. These findings provide valuable reference-gene-selection guidance for functional gene research and gene-expression analysis in T. gallinae.

Identification and functional characterization of annexin A2 in half-smooth tongue sole (Cynoglossus semilaevis)

Annexin A2 (AnxA2), belonging to the annexin family, plays a crucial role in immune responses. In this study, the cDNA of the AnxA2 gene was identified in half-smooth tongue sole, Cynoglossus semilaevis. The transcript of AnxA2 gene in C. semilaevis (CsAnxA2) showed broad tissue distribution, with the highest expression level observed in the gut. CsAnxA2 expression was significantly up-regulated in the intestine, spleen, and kidney tissues following exposure to Shewanella algae. Immunohistochemical staining revealed that CsAnxA2 was predominantly expressed in epithelial cells and significantly elevated after S. algae challenge. Subcellular localization showed that CsAnxA2 was primarily localized in the cytoplasmic compartment. Moreover, proinflammatory cytokines (IL-6, IL-8 and IL-1β) exhibited significant upregulation after CsAnxA2 was overexpressed in vivo. One hundred and fifty-eight CsAnxA2-interacting proteins were captured in the intestinal tissue, showing the top two normalized abundance observed for actin beta (ACTB) and protein S100-A10 (p11). Fifty-four high abundance CsAnxA2-interacting proteins (HIPs) were primary enriched in ten pathways, with the top three significantly enriched pathways being Salmonella infection, glycolysis/gluconeogenesis, and peroxisome proliferator-activated receptor (PPAR) signaling pathway. These results provide valuable information for further investigation into the functional mechanism of AnxA2 in C. semilaevis.

LACpG10-HL Functions Effectively in Antibiotic-Free and Healthy Husbandry by Improving the Innate Immunity

Antibiotics are broadly restricted in modern husbandry farming, necessitating the need for efficient and low-cost immunomodulatory preparations in antibiotic-free and healthful farming. As is known to all, CpG oligonucleotides (CpG-ODNs, an effective innate immunostimulatory agent) recognized by TLR9 in mammals (while TLR21 in avians) could collaborate with some united agent to induce stronger immune responses, but the cost is prohibitively expensive for farmers. Here, considering the coordination between TLR2 and TLR9/TLR21, we firstly proposed the idea that the well-fermented Lactococcus lactis could be utilized as a CpG-plasmid carrier (LACpG10) to enhance the host’s innate immunity against pathogenic invasion. In the present study, after obtaining LACpG10-HL from homogenized and lyophilized recombinant strain LACpG10, we treated primary chicken lymphocytes, two cell lines (HD11 and IPEC-J2), and chickens with LACpG10-HL, CpG plasmids (pNZ8148-CpG10), and other stimulants, and respectively confirmed the effects by conducting qRT-PCR, bacterial infection assays, and a zoological experiment. Our data showed that LACpG10-HL could induce excellent innate immunity by regulating autophagy reactions, cytokine expression, and motivating PRRs. Interestingly, despite having no direct antiseptic effect, LACpG10-HL improved the antibacterial capacities of lymphocytes and enterocytes at the first line of defense. Most importantly, water-supplied LACpG10-HL treatment reduced the average adverse event rates, demonstrating that LACpG10-HL maintained its excellent immunostimulatory and protective properties under farming conditions. Our research not only contributes to revealing the satisfactory effects of LACpG10-HL but also sheds new light on a cost-effective solution with optimal immune effects in green, antibiotic-free, and healthful husbandry farming.

Genome-wide identification of the traf gene family in yellow catfish (Pelteobagrus fulvidraco) and analysis of their expression in response to bacterial challenge

Tumour necrosis factor (TNF) receptor-associated factor (TRAF) is a receptor protein that has important functions in the immune system. Nonetheless, there have been few reports of traf genes in teleost fishes. The present study aimed to identify the traf genes from the genomic information of yellow catfish (Pelteobagrus fulvidraco). Eight traf genes were identified and named, which are distributed on different chromosomes but have similar conserved protein domains. Phylogenetic and syntenic analyses demonstrated conservation of traf genes during evolution. In addition, yellow catfish has the relatively rare traf1 and traf5 genes. Gene structure and motif analysis revealed the homology and distribution diversity of the traf genes. Quantitative real-time reverse transcription PCR was used to study the expression patterns of traf genes in healthy fish tissues and after infection by Aeromonas hydrophila. The results demonstrated significant changes in traf gene expression, indicating a potential role in innate immunity.

YBX has functional roles in CpG-ODN against cold stress and bacterial infection of Misgurnus anguillicaudatus

Misgurnus anguillicaudatus (M. anguillicaudatus) is a widely cultivated fish. However, in M. anguillicaudatus breeding, the frequent cold stress during daily breeding could induce immune suppression and increase the risk of infection, causing serious economic loss. Based on existing findings, CpG Oligonucleotides (CpG-ODNs) may be an ideal protective agent for low temperature fish breeding, performing anti-infective when faced with cold stress with cold shock proteins Y box binding proteins (YBX). Although YBX has pleiotropic functions, its roles in CpG-ODNs-mediated immunity (especially under cold situations) remain largely unexplored. To clarify the relationship among them, we identified the YBX1/YBX2 in M. anguillicaudatus and analyzed using a series of bioinformatics methods. After that, we immunized the fish with 3 types of CpG-ODNs and challenged with Aeromonas hydrophila (A. hydrophila). Here we showed that the best anti-bacterial effect of CpG-B was accompanied by the significant upregulation of YBX1. And the detection of the YBX1 downstream effectors confirmed that CpG-B induced the YBX1-mediated Th1 oriented responses to A. hydrophila by regulation of the NLRP3 (Caspase-A/-B), IL-1β, IL-12 and IFN-γ. Afterwards, we found that under cold stress, CpG-B can activate the NLRP3 and NF-κB pathways through YBX1, a key mediator of anti-A. hydrophila in CpG-B immunization. In this study, we demonstrated CpG-B protection against infection in low temperature, and its interaction with YBX1, expanded the research of CpG-ODN under cold stress, and provided a new CpG-ODN application for low temperature fish farming.