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Tumor necrosis factor α1 (TNFα) is a pleiotropic cytokine involved in immune regulation and cellular homeostasis, but the crucial role of TNFα in fish gut remained unclear. The current study aimed to evaluate the immunoregulatory function of TNFα1 on gut barrier in a novel hybrid fish (WR), which was produced by crossing white crucian carp (Carassius cuvieri, ♀) with red crucian carp (Carassius auratus red var, ♂). In this study, WR‐tnfα1 sequence was identified, and a high‐level expression was detected in the intestine. Elevated levels of WR‐tnfα1 expressions were detected in immune‐related tissues and cultured fish cells on stimulation. The appearance of vacuolization and submucosal rupture was observed in TNFα1‐treated midgut of WR, along with elevated levels of goblet cell atrophy, whereas no significant changes were detected in most expressions of tight‐junction genes and mucin genes. In contrast, WR receiving gut perfusion with WR‐TNFα1 showed a remarkable decrease in antioxidant status in midgut, whereas the expression levels of apoptotic genes and redox responsive genes increased sharply. These results suggested that TNFα1 could exhibit a detrimental effect on antioxidant defense and immune regulation in the midgut of WR. [ABSTRACT FROM AUTHOR]

The survival of farmed fish can be threatened by incidence of Aeromonas hydrophila infection. In addition, gut infection may promote dysbiosis of gut flora and dysregulate immune response in gut-liver axis in teleost fish. The current study aimed to evaluate the pathogenesis of A. hydrophila on gut barrier breach and synchronized immune response in gut-liver axis of RCCs. RCCs were subjected to continuous anal-intubation with A. hydrophila. Midgut sections were stained with periodic acid-Schiff (PAS) and immune-related gene expressions and biochemical indices in gut-liver axis were investigated. The severe midgut injury was detected in RCC anal-intubated with A. hydrophila, along with atrophy of the midgut villi, and the expression levels of tight junction (TJ) genes were consistently lower than those of the control (P < 0.05). Moreover, RCC receiving anal intubation with A. hydrophila showed the upregulation of pathological indices and immure genes in the midgut and liver. These findings demonstrated that gut infection with A. hydrophila can significantly disrupt epithelial permeability to exacerbate gut barrier breach and increase bacterial burdens in tissues as well as dysregulate immune response in gut-liver axis of RCC. [ABSTRACT FROM AUTHOR]

Aeromonas hydrophila can pose a great threat to the survival of farmed fish. In current study, we investigated the pathological characteristics and immune response in gut–liver axis of white crucian carp (WCC) upon gut infection. WCC anally intubated with A. hydrophila exerted a tissue deformation in damaged midgut with elevated levels of goblet cells along with a significant decrease in tight junction proteins and villi length‐to‐width ratios. In addition, immune‐related gene expressions and antioxidant properties increased dramatically in gut–liver axis of WCC following gut infection with A. hydrophila. These results highlighted the immune modulation and redox alteration in gut–liver axis of WCC in response to gut infection. [ABSTRACT FROM AUTHOR]

Aeromonas hydrophila is a common pathogen of freshwater fish. In this study, A. hydrophila infection was shown to cause tissue damage, trigger physiological changes as well as alter the expression profiles of immune‐ and metabolic‐related genes in immune tissues of red crucian carp (RCC). Transcriptome analysis revealed that acute A. hydrophila infection exerted a profound effect on mitochondrial oxidative phosphorylation linking metabolic regulation to immune response. In addition, we further identified cellular senescence, apoptosis, necrosis and mitogen‐activated protein kinase signal pathways as crucial signal pathways in the kidney of RCC subjected to A. hydrophila infection. These findings may have important implications for understanding modulation of immunometabolic response to bacterial infection. [ABSTRACT FROM AUTHOR]

NK-lysin, an effector of natural killer (NK) cells and cytotoxic T lymphocytes (CTLs), not only exhibits cytotoxic effect in fish cells, but also participates in the immune defense against pathogenic infection. In this study, ORF sequences of RCC-NK-lysin, WCC-NK-lysin and WR-NK-lysin were 369 bp. Tissue-specific analysis revealed that the highest expressions of RCC-NK-lysin and WCC-NK-lysin were observed in gill, while the peaked level of WR-NK-lysin mRNA was observed in spleen. A. hydrophila infection sharply increased RCC-NK-lysin, WCC-NK-lysin and WR-NK-lysin mRNA expression in liver, trunk kidney and spleen. In addition, elevated levels of NK-lysin mRNA were observed in cultured fin cell lines of red crucian carp (RCC), white crucian carp (WCC) and their hybrid offspring (WR) after Lipopolysaccharide (LPS) challenge. RCC-NK-lysin, WCC-NK-lysin and WR-NK-lysin exerted regulatory roles in inducing ROS generation, modulating mitochondrial membrane potential, decreasing fish cell viability and antagonizing survival signalings, respectively. RCC/WCC/WR-NK-lysin-overexpressing fish could up-regulate expressions of inflammatory cytokines and decrease bacterial loads in spleen. These results indicated that NK-lysin in hybrid fish contained close sequence similarity to those of its parents, possessing the capacities of cytotoxicity and immune defense against bacterial infection. • Structure of NK-lysin in hybrid offspring was compared with those of its parents. • Up-regulated expressions of RCC/WCC/WR-NK-lysin were observed following A. hydrophila challenge and LPS stimulation. • RCC/WCC/WR-NK-lysin could cause the loss of MMP activity and decrease cell viability. [ABSTRACT FROM AUTHOR]

Hepcidin, a multifunctional hormone oligopeptide, not only exhibits a regulatory role in iron metabolism, but also participates in the regulation of teleostean immunity. In this study, ORF sequence of WR-hepcidin was 258 bp and encoded 85 amino acid residues. Tissue-specific analysis revealed that the highest expression of WR-hepcidin was observed in liver. Aeromonas hydrophila challenge can sharply increased WR-hepcidin mRNA expression in liver, trunk kidney and spleen. The purified WR-hepcidin fusion peptide can directly bind to A. hydrophila and Streptococcus agalactiae , reduce the relative bacterial activity, limit bacterial growth and attenuate their dissemination to tissues in vivo. In addition, the treatment of WR-hepcidin fusion protein can diminish the production of pro-inflammatory cytokines. These results indicated that WR-hepcidin can play a negative regulatory role in bacteria-stimulated pro-inflammatory cytokines production and MyD88-IRAK4 activation. • We characterized a novel hepcidin gene in hybrid crucian carp. • The up-regulation of WR-hepcidin was observed following bacterial challenge. • WR-hepcidin can bind to gram positive and gram negative bacteria. • WR-hepcidin can restrict the bacterial growth and reduce bacteria-stimulated inflammatory response. [ABSTRACT FROM AUTHOR]

CD59, a multifunctional glycoprotein, not only plays a regulatory role in complement cascades, but also participates in modulation of teleostean immunity. In this study, full length sequence of EcCD59 was obtained, comprising a 5′UTR of 163 bp, an ORF of 354 bp and a 3′UTR of 559 bp. EcCD59 gene encoded a polypeptide of 117 amino acids. Tissue-specific analysis revealed that the highest expression of EcCD59 mRNA was observed in muscle. Vibrio alginolyticus challenge can significantly increase EcCD59 mRNA expression in liver, kidney and spleen. EcCD59 distribution was detected by a combined approach using GFP-overexpression, immunofluorescence and ELISA assay, indicating that EcCD59 may be predominantly aggregated in cellular membrane. Both EcCD59 and EcCD59delGPI can directly bind to V. alginolyticus and decrease the in vitro growth of V. alginolyticus. Additionally, vibrio injection experiment indicated that the binding of EcCD59 or EcCD59delGPI to V. alginolyticus can restrict its growth rate in vivo. In this study, we found that EcCD59 may be involved in immune defense against vibrio infection in a complement-independent manner. • Full-length sequence of EcCD59 was identified from the orange-spotted grouper. • The up-regulation of EcCD59 was observed following vibrio challenge. • EcCD59 can bind to V. alginolyticus and restrict the growth of V. alginolyticus. • Loss of GPI domain cannot hamper CD59's vibrio-binding and vibrio-inhibitory activity. [ABSTRACT FROM AUTHOR]

Bcl-2 is a pro-survival member of Bcl-2 like superfamily, playing an important role in regulating the apoptotic process. In this study, the full-length Bcl-2 (EcBcl-2) was obtained, consisting of a 5′UTR of 290 bp, an ORF of 699 bp and a 3′UTR of 920 bp. EcBcl-2 gene encoded a polypeptide of 232 amino acids with an estimated molecular mass of 26.12 KDa and a predicted isoelectric point (pI) of 6.93. The deduced amino acid sequence analysis showed that EcBcl-2 consisted of the conserved residues and characteristic domains known to the critical functionality for Bcl-2. qRT-PCR analysis revealed that EcBcl-2 transcript was expressed in all the examined tissues, while the strongest expression level was observed in liver, followed by the expression in blood, gill, kidney, spleen, heart, intestine and muscle. The groupers challenged with V. alginolyticus showed a significant increase of EcBcl-2 mRNA in immune tissues. In addition, western blotting analysis confirmed that the up-regulation of EcBcl-2 protein expression was detected in liver. Subcellular localization analysis revealed that EcBcl-2 was localized in both nucleus and cytoplasm. Overexpression of EcBcl-2 can inhibit the LPS-induced apoptosis and activate the transcription activity of NF-κB and AP-1, while the deletion of BH1, BH2, BH3 or BH4 domain from EcBcl-2 can impede the signaling transduction. These results indicate that EcBcl-2 may play a regulatory role in the apoptotic process. [ABSTRACT FROM AUTHOR]

The tumor suppressor protein p53 plays a critical role in cell cycle, apoptosis and DNA repair. In this study, the full-length pufferfish p53 (Pf-p53) was obtained, containing an open reading frame of 1095 bp, a 5′UTR of 157 bp and a 3′UTR of 285 bp with a poly (A) tail. The Pf-p53 encoded a polypeptide of 364 amino acids with a theoretical isoelectric point of 8.03 and predicted molecular weight of 40.6 kDa. Pf-p53 was ubiquitously expressed in various tissues with a high-level expression in kidney, liver and gill. Vibrio alginolyticus challenge could induce ROS production and disrupt Ca 2+ homeostasis, subsequently leading to the induction of DNA damage and apoptosis, while the Vibrio alginolyticus -induced oxidative stress can also increase the non-specific immunity. The pufferfish challenged with Vibrio alginolyticus showed a sharp increase of Pf-p53 transcript in liver. Subcellular localization analysis revealed that Pf-p53 was primarily localized in nucleus. Furthermore, overexpression of Pf-p53 in Hela cells could inhibit cell proliferation and the transcriptional activities of the NF-ĸB promoter. Taken together, our results indicated that Pf-p53 may play an important role in the immune response to Vibrio alginolyticus challenge. [ABSTRACT FROM AUTHOR]

PTEN is a key tumor suppressor gene that can play a regulatory role in the cellular proliferation, survival and apoptosis. In this study, the full-length PTEN (EcPTEN) was obtained, containing a 5′UTR of 745 bp, an ORF of 1269 bp and a 3′UTR of 106 bp. The EcPTEN gene encoded a polypeptide of 422 amino acids with an estimated molecular mass of 49.14 KDa and a predicted isoelectric point (pI) of 6.34. The deduced amino acid sequence analysis showed that EcPTEN comprised the conserved residues and the characteristic domains known to the critical functionality of PTEN. qRT-PCR analysis revealed that EcPTEN mRNA was broadly expressed in all the examined tissues, while the highest expression level was observed in liver, followed by the expression in blood, kidney, spleen, heart, gill, muscle and intestine. The groupers challenged with Vibrio alginolyticus showed a sharp increase of EcPTEN mRNA expression in immune tissues. In addition, western blotting analysis confirmed that the up-regulation of EcPTEN protein expression was steadily induced in liver. Subcellular localization analysis indicated that EcPTEN was localized in both nucleus and cytoplasm. Overexpression of EcPTEN can activate the apoptotic cascade and abrogate NF-kB, AP-1, Stat3 and Myc promoter activity in Hela cells. These results indicated that EcPTEN harboring highly-conserved domains with a close sequence similarity to those of PTP superfamily may disrupt the mammalian signalings and play a regulatory role in the apoptotic process. [ABSTRACT FROM AUTHOR]

Bax is a pro-apoptotic member of Bcl-2 like superfamily, playing an important role in regulating the apoptosis. In this study, the full-length Bax (EcBax) was obtained, containing a 5′UTR of 64 bp, an ORF of 579 bp and a 3′UTR of 1021 bp. The EcBax gene encoded a polypeptide of 192 amino acids with an estimated molecular mass of 21.55 KDa and a predicted isoelectric point (pI) of 6.75. The deduced amino acid sequence analysis showed that EcBax comprised the conserved residues and the characteristic domains known to the critical function of Bax. qRT-PCR analysis revealed that EcBax mRNA was broadly expressed in all of the examined tissues, while the highest expression level was observed in blood, followed by the expression in liver, gill, spleen, kidney, heart, muscle and intestine. A sharp increase of EcBax expression was observed in the vibrio challenge group by comparing with those in the control. Subcellular localization analysis revealed that EcBax was predominantly localized in the cytoplasm. EcBax exerted a regulatory role in modulating the mitochondrial membrane potential, promoting the cytochrome c release, and then activating the downstream caspase signaling. Moreover, the overexpression of EcBax can decrease the cell viability and antagonize NF-kB, AP-1, Stat3 promoter activity in Hela cells. These results indicate that EcBax containing the conserved domain of pro-apoptotic member of Bcl-2 family may disrupt the mammalian signaling and play a regulative role in the apoptotic process. [ABSTRACT FROM AUTHOR]

The effect of Ec-FABP10 (Epinephelus coiodes-FABP10) on growth performance, enzyme activity, respiratory burst, MDA level, ATP content, immune-related gene expression of juvenile orange-spotted grouper (E. coioides). The commercial diet supplemented with FABP10 protein was feed to orange-spotted grouper for six weeks. No significant difference was observed in the specific growth rates, while the survival rate in the FABP10 additive group was significantly higher. After the feeding trial, the groupers were exposed to acute low temperature challenge. The decreased level of respiratory burst activity was observed in the FABP10 additive group after the exposure to the acute low temperature stress, while the blood cell count increased significantly at 15 °C and a significant increase of ATP content was observed at 10 °C. Higher enzymatic activities of CAT and SOD were observed at 20 °C and 15 °C, respectively. Meanwhile, the lower level of MDA was observed after the exposure to acute low temperature challenge by comparing with the controls. Further transcript expression analyses of FABP10, SOD2, GPX4, HSPA4 and LIPC in liver by quantitative real-time PCR demonstrated that the up-regulated transcript expression of FABP10, SOD2, HSPA4 and LIPC was observed in FABP10 additive group at 15 °C, while the transcript expression of GPX4 increased significantly at 20 °C. Western blotting analysis confirmed that FABP10 protein expression strongly increased at 15 ± 0.5 °C in FABP10 additive group. These results showed that FABP10 additive diet could moderate the metabolic and immune abilities mainly via ROS pathway in the orange-spotted grouper. [ABSTRACT FROM AUTHOR]

Ferritin H can participate in the regulation of fish immunity. Tissue-specific analysis revealed that the highest expressions of Ferritin H in parental species were observed in spleen, while peaked level of Ferritin H mRNA in hybrid fish was observed in liver. In addition, A. hydrophila challenge could sharply enhance their Ferritin H mRNA expression in liver, kidney and spleen. To further investigate their roles in immune regulation, their Ferritin H fusion proteins were produced in vitro. Ferritin H fusion proteins could exhibit a direct binding activity to A. hydrophila and endotoxin in a dose-dependent manner, restrict dissemination of A. hydrophila to tissues and abrogate inflammatory cascades. Moreover, treatment with Ferritin H fusion proteins could reduce A. hydrophila -induced lipid peroxidation. These results indicated that Ferritin H in hybrid fish elicited a similar immune regulation of A. hydrophila -induced inflammatory signals in comparison with those of its parents. [Display omitted] • Up-regulation of RCC/WCC/WR-ferritin H was observed following A. hydrophila challenge. • RCC/WCC/WR-ferritin H could directly bind to A. hydrophila and LPS. • RCC/WCC/WR-ferritin H could diminish A. hydrophila -induced inflammatory response. [ABSTRACT FROM AUTHOR]

Ferritin H can participate in the regulation of teleostean immunity. ORF sequences of RCC/WCC/WR-ferritin H were 609 bp, while WR-ferritin H gene possessed chimeric fragments or offspring-specific mutations. In order to elucidate regulation of immune-related signal transduction, three fibroblast-like cell lines derived from caudal fin of red crucian carp (RCC), white crucian carp (WCC) and their hybrid offspring (WR) were characterized and designated as RCCFCs, WCCFCs and WRFCs. A sharp increase of ferritin H mRNA was observed in RCCFCs, WCCFCs and WRFCs following lipopolysaccharide (LPS) challenge. Overexpression of RCC/WCC/WR-ferritin H can decrease MyD88-IRAK4 signal and antagonize NF-κB, TNFα promoter activity in RCCFCs, WCCFCs and WRFCs, respectively. These results indicated that ferritin H in hybrid offspring harbors highly-conserved domains with a close sequence similarity to those of its parents, playing a regulatory role in inflammatory signals. Unlabelled Image • We characterized fin cell lines derived from hybrid crucian carp and its parents. • Structure of chimeric ferritin H in hybrid offspring was compared with those of its parents. • Up-regulated expressions of RCC/WCC/WR-ferritin H were observed following LPS stimulation. • Overexpression of RCC/WCC/WR-ferritin in fish cells can abrogate NF-κB promoter activity. [ABSTRACT FROM AUTHOR]

LEAP-2, a multifunctional peptide, not only exhibits a regulatory role in pathogenic infection, but also participates in the regulation of teleostean immunity. In this study, ORF sequence of WR-LEAP-2 was 240 bp and encoded 79 amino acid residues. Tissue-specific analysis revealed that the highest expression of WR-LEAP-2 was observed in liver. Aeromonas hydrophila challenge can sharply increase WR-LEAP-2 mRNA expression in liver, kidney and spleen. The purified WR-LEAP-2 peptide can directly bind to A. hydrophila and S. agalactiae , reduce the relative bacterial activity and limit bacterial growth in vitro. In addition, the treatment of WR-LEAP-2 can restrict bacterial dissemination in vivo and reduce production of pro-inflammatory cytokines. These results indicated that WR-LEAP-2 can confer protection against A. hydrophila - or S. agalactiae -stimulated MyD88-dependent pro-inflammatory cytokines activation. Unlabelled Image • We characterized a novel LEAP-2 gene in hybrid crucian carp. • The up-regulation of WR-LEAP-2 was observed following bacterial challenge. • WR-LEAP-2 can bind to A. hydrophila or S. agalactiae and restrict their growth. • WR-LEAP-2 can diminish A. hydrophila - or S. agalactiae -induced inflammatory response. [ABSTRACT FROM AUTHOR]

Hybrid genotypes in fish may be less susceptible to pathogenic infection. ITLN, a novel lectin, not only exhibits a regulatory role in pathogenic infection, but also participates in the regulation of teleostean immunity. In this study, ORF sequence of WR-ITLN was 945 bp and encoded 314 amino acid residues. Tissue-specific analysis revealed that the highest expression of WR-ITLN was observed in liver. Aeromonas hydrophila challenge can sharply increased WR-ITLN mRNA expression in liver, kidney and spleen. The purified WR-ITLN protein can directly bind to A. hydrophila and S. agalactiae , reduce their relative bacterial activity and limit bacterial growth in vitro in the presence of Ca2+. In addition, the treatment of WR-ITLN + Ca2+ can restrict bacterial dissemination in vivo and attenuate production of pro-inflammatory cytokines. These results indicated that WR-ITLN can confer protection against bacteria-stimulated MyD88-dependent pro-inflammatory cytokines activation in a Ca2+-dependent manner. • We characterized a novel ITLN gene in hybrid crucian carp. • The up-regulation of WR-ITLN was observed following bacterial challenge. • WR-ITLN can bind to gram-positive or gram-negative bacteria and restrict their growth in the presence of Ca2+. • Combined treatment of WR-ITLN + Ca2+ can diminish bacteria-stimulated inflammatory response. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel HN-AD bacterium, A. pittii J08, was isolated from pond sediments. • High removals of inorganic N and TN-N were analyzed in different N conditions. • Whole genome sequence and N metabolic pathways were analyzed. • Strain J08 showed a high adaptability to various culture conditions. A novel A. pittii J08 with heterotrophic nitrification and aerobic denitrification (HN-AD) isolated from pond sediments could rapidly degrade inorganic nitrogen (N) and total nitrogen (TN-N) with ammonium (NH 4 +-N) preference. N degradation rate of NH 4 +-N, nitrite (NO 2 −-N) and nitrate (NO 3 −-N) were 3.9 mgL−1h−1, 3.0 mgL−1h−1 and 2.7 mgL−1h−1, respectively. In addition, strain J08 could effectively utilize most of detected low-molecular-weight carbon (LMWC) sources to degrade inorganic N with a wide adaptability to various culture conditions. Whole genome sequencing (WGS) analysis revealed that assembled genome of stain J08 possessed the crucial genes involved in dissimilatory/assimilatory NO 3 −-N reduction and NH 4 +-N assimilation. These results indicated that strain J08 could be applied to wastewater treatment in aquaculture. [ABSTRACT FROM AUTHOR]

FerL, a multifunctional iron-storage polypeptide, not only exhibited a regulatory role in iron metabolism, but also participated in the regulation of fish immunity. In this study, ORF sequence of WR-FerL was 522 bp, encoding 173 amino acid residues. Tissue-specific analysis revealed that the highest expression of WR-FerL was detected in spleen. A. hydrophila challenge and LPS stimulation could sharply enhance WR-FerL mRNA expression in tissues and fish cells, respectively. Purified WR-FerL fusion peptide exhibited in vitro binding activity to A. hydrophila and endotoxin, limited bacterial dissemination to tissues as well as attenuated A. hydrophila -induced production of pro-inflammatory cytokines. Moreover, WR-FerL overexpression could abrogate NF-κB and TNFα promoter activity in fish cells. These results indicated that WR-FerL could play an important role in host defense against A. hydrophila infection. • A novel FerL gene was characterized in hybrid crucian carp. • A. hydrophila challenge and LPS stimulation could increase expressions of WR-FerL mRNA. • WR-FerL could elicit a binding activity to A. hydrophila and LPS. [ABSTRACT FROM AUTHOR]

Aeromonas hydrophila can pose a great threat to survival of freshwater fish. In this study, A. hydrophila infection could decrease blood cell numbers, promote blood cell damage as well as alter the levels of alkaline phosphatase (ALP), lysozyme (LZM), aspartate aminotransferase (AST), total antioxidant capacity (T-AOC), total superoxide dismutase (SOD), catalase (CAT) and malondialdehyde (MDA) in immune-related tissues of red crucian carp (RCC, 2 N = 100) and triploid cyprinid fish (3 N fish, 3 N = 150). In addition, the significant alternation of antioxidant status was observed in PBMCs isolated from RCC and 3 N following LPS stimulation. The core differential expression genes (DEGs) involved in apoptosis, immunity, inflammation and cellular signals were co-expressed differentially in RCC and 3 N following A. hydrophila challenge. NOD-like receptor (NLR) signals appeared to play a critical role in A. hydrophila- infected fish. DEGs of NLR signals in RCCah vs RCCctl were enriched in caspase-1-dependent Interleukin-1β (IL-1β) secretion, interferon (IFN) signals as well as cytokine activation, while DEGs of NLR signals in 3Nah vs 3Nctl were enriched in caspase-1-dependent IL-1β secretion and antibacterial autophagy. These results highlighted the differential signal regulation of different ploidy cyprinid fish to cope with bacterial infection. • Blood cells of triploid cyprinid fish exhibited a higher resistance against A. hydrophila -induced cell damage. • Acute A. hydrophila infection could dramatically alter non-specific immunity in different ploidy cyprinid fish. • Acute A. hydrophila infection could trigger the difference in signal regulation in different ploidy cyprinid fish. [ABSTRACT FROM AUTHOR]

Aeromonas hydrophila can pose a great threat to fish survival. In this study, we investigated the differential immune and redox response in gut-liver axis of hybrid fish (WR) undergoing gut infection. WR anally intubated with A. hydrophila showed severe midgut injury with decreased length-to-width ratios of villi along with GC hyperplasia and enhanced antioxidant activities, but expression profiles of cytokines, chemokines, antibacterial molecules, redox sensors and tight junction proteins decreased dramatically. In contrast, immune-related gene expressions and antioxidant activities increased significantly in liver of WR following gut infection with A. hydrophila. These results highlighted the differential immune regulation and redox balance in gut-liver axis response to bacterial infection. [Display omitted] • Severe midgut injury with GC hyperplasia was observed in WR anally intubated with A. hydrophila. • Suppressions of tight junction molecules were observed in midgut of WR following gut infection. • WR receiving gut infection with A. hydrophila exhibited differential immune and redox response in gut-liver axis. [ABSTRACT FROM AUTHOR]

Aeromonas hydrophila is one of important pathogenic bacteria that can imperil fish survival. Current study suggested that hybrid crucian carp (WR) receiving acute A. hydrophila challenge exerted a molecular regulation linking peroxisomal fatty acid β-oxidation to immune response. A. hydrophila infection may alleviate antioxidant status along with the significant alternation of immune-, apoptosis- and metabolic-related gene expressions in kidney, whereas most portions of differential metabolites (DMs) were enriched in steroid derivatives and phospholipids. In addition, mevalonate (MVA) pathway and phospholipid hydrolysis were identified as crucial cellular processes in WR after A. hydrophila challenge. These results may provide an insight into immunometabolic strategy against A. hydrophila infection. • Acute A. hydrophila infection could induce antioxidant imbalance in WR. • Changes of immune- and metabolic-related gene expressions in kidney were observed. • A. hydrophila infection exhibit a profound effect on MVA pathway and phospholipid hydrolysis. [ABSTRACT FROM AUTHOR]