Dietary aflatoxin B1 caused the growth inhibition, and activated oxidative stress and endoplasmic reticulum stress pathway, inducing apoptosis and inflammation in the liver of northern snakehead (Channa argus)

Chronic exposure to palm oil mill effluent induces oxidative stress and histopathological changes in zebrafish (Danio rerio)

Several studies have revealed that Palm Oil Mill Effluent (POME) adversely affects fish health systems in various ways. However, further studies on oxidative stress and histopathological changes in fish tissues exposed to POME are essential so that a more comprehensive and detailed understanding of its toxicity is attained. Subsequently, this study investigated oxidative stress indicators, including malondialdehyde (MDA) content and activities of antioxidant enzymes, as well as histological changes in zebrafish (Danio rerio) tissues after chronic exposure to POME. The results showed a significant increase in MDA content by up to 122 % in gills and 351 % in liver, while catalase (CAT) activity rose by 70 % in gills and 170 % in liver. Glutathione S-transferase (GST) activity was significantly reduced by 50 % in both tissues, while superoxide dismutase (SOD) activity increased by 162 % in the liver, yet showed no significant change in gills. Histological analysis revealed mild to severe alterations in gills (e.g., hyperplasia, hypertrophy, hemorrhage, and necrosis) and liver (e.g., hepatocyte shrinkage, congestion, hydropic degeneration, and necrosis) at higher POME concentrations and longer exposure durations. These findings suggest that oxidative stress markers and histopathological changes potentially serve as early warning indicators for: firstly, assessing POME contamination in aquatic environments; and secondly, evaluating the effectiveness of wastewater treatment systems.

Mitigating Aflatoxin B1-Induced Growth Impairment and Hepatic Stress in Nile Tilapia (Oreochromis niloticus): Comparative Efficacy of Saccharomyces cerevisiae and Silicate-Based Detoxifiers

The objective of this study was to detect the effects of acute aflatoxin B1 (AFB1) exposure in Nile tilapia (Oreochromis niloticus) and the effectiveness of Saccharomyces cerevisiae and silicate in reducing these effects. Two hundred and forty Nile tilapia fingerlings (16 ± 0.5 g) were randomly assigned to four experimental groups, each with 60 fish and three replicates. Control basal diet (Diet 1) and three test diets were formulated, where Diet 2 was supplemented with 200 ppb AFB1. Diets 3 and 4 were intoxicated with AFB1 (200 ppb) and supplemented with 0.5% S. cerevisiae or 0.5%, respectively. After 60 days, Diet 1 had considerably greater growth characteristics than the other groups (p < 0.05). Diet 2 revealed a reduced (p < 0.05) survival rate after 1 month of exposure. In addition, Diet 1 showed higher (p < 0.05) total protein and albumin levels than Diets 3 and 4. AFB1 residues were detected in the liver in fish-fed Diet 2, Diet 4, and Diet 3. Alanine aminotransferase, aspartate aminotransferase, creatinine, and urea levels increased (p < 0.05) in fish-fed Diet 2. The glutathione peroxidase, lysozyme, and catalase activity were decreased (p < 0.05) in the fish-fed Diet 2. The malondialdehyde level was significantly higher in fish given Diet 2 (p < 0.05) than in fish-fed Diets 3 and 4. Histopathological investigation of fish-fed Diet 2 revealed impaired liver and spleen; however, both treatments (Diets 3 and 4) successfully lowered inflammation and preserved liver and spleen integrities. In conclusion, AFB1 impaired growth performance and posed a severe health risk to Nile tilapia. Furthermore, S. cerevisiae alleviated the contamination of AFB1 effects more efficiently than silicate employed for toxin adsorption.

Protective effect of curcumin against endoplasmic reticulum stress and lipid metabolism disorders in AFB1-intoxicated duck liver

Aflatoxin B1 (AFB1) is a stable and highly toxic toxin that causes multi-organ toxicity with sustained ingestion, most typically in the duck liver. Previous research has shown that AFB1 can bring about endoplasmic reticulum stress (ERS) in animals, and ERS is strongly associated with lipid metabolism. However, the relationship between AFB1-induced duck liver toxicity and ERS and lipid metabolism is currently unclear. Great attention has been paid to the prevention and treatment of AFB1 because of its great harm. Curcumin, a natural polyphenol, is notable for its powerful anti-inflammatory and antioxidant properties. Studies have shown curcumin to be protective against afb1-induced avian multi-organ toxicity. However, the effects of curcumin on the liver of ducks exposed to AFB1 are largely unknown. In the present study, we aimed to investigate whether AFB1 exposure induces ERS and lipid metabolism disorders in duck liver, while exploring the positive role of curcumin in it. One-day-old ducks (n = 80) were randomly divided in four groups: control group, AFB1 group (0.1 mg / kg.bw AFB1), Cur group (400 mg/kg curcumin), and AFB1 + Cur group (0.1 mg/kg.bw AFB1 + 400 mg/kg curcumin), and blood and liver were collected for the study after 21 days of continuous administration. Our research has found that AFB1 exposure significantly increases the levels of liver function indicators ALP, AST, and ALT in ducks' serum (P < 0.05). Duck liver undergoes fatty degeneration under the influence of AFB1. Under the effect of curcumin, AFB1-induced structural damage in duck liver was somewhat controlled. Further experimental results showed that AFB1 treatment significantly increased the expression of glucose-regulated protein 78 (P < 0.001), and activated the endoplasmic reticulum stress pathway. Meanwhile, AFB1 inhibited the LKB1-AMPK signaling pathway and disrupted lipid metabolic homeostasis. And curcumin treatment effectively reversed these changes. Overall, our results suggest that curcumin attenuates AFB1-induced hepatotoxicity in ducks by inhibiting ERS and lipid metabolism disorders.

Cow Placenta Peptides Ameliorate D-Galactose-Induced Intestinal Barrier Damage by Regulating TLR/NF-κB Pathway

This study investigated the protective effects and mechanisms of cow placenta peptides (CPP) on intestinal barrier damage in aging model mice. Forty-eight male ICR mice were assigned to four groups: a control group (N), an aging model group (M), a CPP treatment group (T), and a vitamin C treatment group (P). Groups T and P received oral administration of CPP (2000 mg/kg/day) and vitamin C (100 mg/kg/day), respectively, while groups M, T, and P were subjected to intraperitoneal injections of D-galactose (D-gal) (300 mg/kg/day). Group N received an equivalent volume of normal saline via intraperitoneal injection. Treatments were administered once daily for 8 weeks. The results demonstrated that CPP significantly alleviated D-galactose-induced intestinal structural damage, increasing the villus height-to-crypt depth ratio and reducing serum diamine oxidase (DAO) and lipopolysaccharide (LPS) levels. CPP notably alleviated intestinal oxidative stress and inflammation, restored tight junction expression, and enhanced intestinal barrier integrity. Transcriptome sequencing identified 1396 DEGs associated with CPP's effects, highlighting TLR4, IL-1β, and Mmp9 as core regulatory genes through protein-protein interaction network analysis. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology enrichment analyses implicated the TLR4/NF-κB signaling pathway, which was further validated. Western blotting confirmed that CPP significantly down-regulated TLR4, IKKβ, and p-NF-κB p65 protein expression in the intestines of aging mice. In conclusion, CPP effectively alleviates D-gal-induced intestinal barrier damage in aging mice by enhancing antioxidant defense and inhibiting the TLR4/NF-κB signaling pathway, thereby diminishing inflammation and protecting intestinal barrier integrity.

Protection of glutamine: The NF-κB/MLCK/MLC2 signaling pathway mediated by tight junction affects oxidative stress, inflammation and apoptosis in snakehead (Channa argus)

Lipopolysaccharide (LPS) destroys intestinal mechanical barrier and causes apoptosis by triggering oxidative stress and inflammatory responses. Glutamine (Gln) can maintain normal intestinal function under various stressed or pathological conditions. Thereby, this study aims to evaluate the protection of glutamine on intestinal health of snakehead (Channa argus), specifically regarding the NF-κB/MLCK/MLC2 signaling pathway mediated by tight junction affecting oxidative stress, inflammation and apoptosis. In this work, a model of intestinal tight junction injury in intestine of snakehead was constructed by injecting 4 mg/mL LPS into anus for 96 h. Before constructing the model, fish were treated with different levels of alanyl-glutamine (Ala-Gln) (0 %, 0.3 %, 0.6 %, 0.9 %, 1.2 % and 1.5 %) for 56 days. Microstructure and ultra microstructure showed that LPS-induced obvious intestinal damage and tight connection destruction, while Gln effectively alleviated these phenomena. In addition, results also showed that Gln can effectively inhibit LPS-induced damage to intestinal tight junction (zo-1, occludin, claudin5, claudin1, nf-κb p65, mlck and mlc2), alleviate oxidative stress (nrf2, sod, gsh, gpx and cat), ameliorate intestinal inflammation (tnf-α, il-1β, il-8, tlr5 and tlr2), thereby reduce apoptosis (p38mapk, caspase9, caspase8, caspase3 and bax). Crucially, the above results were related to NF-κB/MLCK/MLC2 signaling pathway mediated by tight junction. In conclusion, Gln has a good protective effect on LPS-induced intestinal injury in northern snakehead, providing a new perspective for regulating fish intestinal health.

A Brief Review on Aflatoxicosis in Aquaculture With a Focus on Fish

Feed quality is among the most determinative criteria for aquaculture success. Along with feed ingredient quality and its production process, feed storage conditions would also affect feed quality, especially in terms of adventitious toxins. Mycotoxins are frequent food and feed contaminants and are considered important health threats to both human and animal health. In this context, the effects of mycotoxins on aquatic animals were reviewed with an emphasis on aflatoxin B1 (AFB1), which is obviously reported in aquafeed. Severe tissue damage, increased susceptibility to infectious diseases, compromised immune system function, and increasing unknown death risks are among the most frequent symptoms of aflatoxicosis in aquatic animals. The lowest observable effect level for AFB1 has also been documented for different fish species. Considering the importance of such fungal toxins on the economic viability of aquaculture enterprises, it is recommended that further knowledge be obtained concerning the safe levels of AFB1 in terms of fish health and final product safety to human consumers.

Proanthocyanidins mitigate the toxic effects in loach (Misgurnus anguillicaudatus) exposed to phenanthrene via Nrf2/NF-κB signaling pathway

Phenanthrene (PHE) is a typical polycyclic aromatic hydrocarbon compound that is ubiquitous in the environment and accumulates in aquatic products, thereby posing a risk to food safety. Oligomeric proanthocyanidins (OPC) is widely distributed powerful antioxidants with potent antioxidant and anti-inflammatory properties. This study aimed to evaluate the alleviating effects of dietary OPC on oxidative stress, inflammatory suppression, and tissue damage caused by PHE exposure in loach (Misgurnus anguillicaudatus). In the study, loach was continuously exposed to 2.36 mg/L PHE for 28 days, after which they were fed a basal diet supplemented with 0, 200, 400, or 800 mg/kg OPC. The results displayed that PHE exposure resulted in significantly increased levels of liver health parameters (AST, ALT, COR, LDH, and ADA) compared to the control group (P < 0.05). The PHE-exposed fish showed the lowest levels of antioxidant enzymes (CAT, SOD, GSH, GST, GSH-Px, and GR) and the greatest levels of oxidative stress parameters (ROS and MDA). PHE exposure resulted in down-regulation of nrf2, ho-1, gsh-px, gst, and nqo-1, and up-regulation of keap-1 gene expressions in loach (P < 0.05). Moreover, PHE-induced decreased the levels of immunity indicators (CRP, MPO, C3, C4, IgM, and LYS). An up-regulation of pro-inflammatory genes (nf-κb, il-1β, il-8, il-6, il-12, and tnf-α) and a down-regulation of anti-inflammatory gene il-10 were the consequences of the PHE exposure. In addition, tissues showed histopathological alterations including vacuolization (liver), displaced nuclei (liver), atrophy (gills), glomerular congestion (kidney), and inflammatory cell infiltration (spleen) caused by PHE. Notably, dietary supplementation of OPC augmented immuno-antioxidant parameters, including their key genes, reduced oxidative stress and immunosuppression, and ameliorated tissue damage compared to fish exposed to PHE. In summary, supplementation with 400 mg/kg OPC in the diets could effectively alleviate the oxidative damage and inflammatory response induced by PHE exposure in loach through the Nrf2/NF-κB signaling pathway and enhance the defense ability against toxic substances of loach.

Changes of intestinal barrier in the process of intestinal inflammation induced by Aeromonas hydrophila in snakehead (Channa argus)

Bacterial intestinal inflammation frequently occurs in cultured fish. Nevertheless, research on intestinal barrier dysfunction in the process of intestinal inflammation is deficient. In this study, we explored the changes of intestinal inflammation induced by Aeromonas hydrophila (A. hydrophila) in snakehead and the relationship between intestinal barrier and inflammation. Snakehead [(13.05 ± 2.39) g] were infected via anus with A. hydrophila. Specimens were collected for analysis at 0, 1, 3, 7 and 21 d post-injection. The results showed that with the increase of exposure time, the hindgut underwent stages of normal function, damage, damage deterioration, repair and recovery. Relative to 0 d, the levels of IL-1β and TNF-α in serum, and the expression of nod1, tlr1, tlr5, nf-κb, tnf-α and il-1β in intestine were significantly increased, and showed an upward then downward pattern over time. However, the expression of tlr2 and il-10 were markedly decreased, and showed the opposite trend. In addition, with the development of intestinal inflammation, the diversity and richness of species, and the levels of phylum and genus in intestine were obviously altered. The levels of trypsin, LPS, AMS, T-SOD, CAT, GPx, AKP, LZM and C3 in intestine were markedly reduced, and displayed a trend of first decreasing and then rebounding. The ultrastructure observation showed that the microvilli and tight junction structure of intestinal epithelial cells experienced normal function initially, then damage, and finally recovery over time. The expression of claudin-3 and zo-1 in intestine were significantly decreased, and showed a trend of first decreasing and then rebounding. Conversely, the expression of mhc-i, igm, igt and pigr in intestine were markedly increased, and displayed a trend of increasing first and then decreasing. The above results revealed the changes in intestinal barrier during the occurrence and development of intestinal inflammation, which provided a theoretical basis for explaining the relationship between the two.

Dietary Clostridium autoethanogenum protein has dose-dependent influence on the gut microbiota, immunity, inflammation and disease resistance of abalone Haliotis discus hannai

Clostridium autoethanogenum protein (CAP) is an eco-friendly protein source and has great application potential in aquafeeds. The present study aimed to investigate the effects of dietary CAP inclusion on the anti-oxidation, immunity, inflammation, disease resistance and gut microbiota of abalone Haliotis discus hannai after a 110-day feeding trial. Three isonitrogenous and isolipidic diets were formulated by adding 0 % (control), 4.10 % (CAP4.10) and 16.25 % (CAP16.25) of CAP, respectively. A total of 540 abalones with an initial mean body weight of 22.05 ± 0.19 g were randomly distributed in three groups with three replicates per group and 60 abalones per replicate. Results showed that the activities of superoxide dismutase and glutathione peroxidase in the cell-free hemolymph (CFH) were significantly decreased and the content of malondialdehyde in CFH was significantly increased in the CAP16.25 group. The diet with 4.1 % of CAP significantly increased the activities of lysozyme and acid phosphatase in CFH. The expressions of pro-inflammatory genes such as tumor necrosis factor-α (tnf-α), nuclear factor-κb (nf-κb) and toll-like receptor 4 (tlr4) in digestive gland were downregulated, and the expressions of anti-inflammatory genes such as β-defensin and mytimacin 6 in digestive gland were upregulated in the CAP4.10 group. Dietary CAP inclusion significantly decreased the cumulative mortality of abalone after the challenge test with Vibrio parahaemolyticus for 7 days. Dietary CAP inclusion changed the composition of gut microbiota of abalone. Besides, the balance of the ecological interaction network of bacterial genera in the intestine of abalone was enhanced by dietary CAP. The association analysis showed that two bacterial genera Ruegeria and Bacteroides were closely correlated with the inflammatory genes. In conclusion, the 4.10 % of dietary CAP enhanced the immunity and disease resistance as well as inhibited the inflammation of abalone. The 16.25 % of dietary CAP decreased the anti-oxidative capacity of abalone. The structure of the gut microbiota of abalone changed with dietary CAP levels.

Neurotoxic mechanisms of mycotoxins: Focus on aflatoxin B1 and T-2 toxin

Aflatoxin B1 (AFB1) and T-2 toxin are commonly found in animal feed and stored grain, posing a serious threat to human and animal health. Mycotoxins can penetrate brain tissue by compromising the blood-brain barrier, triggering oxidative stress and neuroinflammation, and leading to oxidative damage and apoptosis of brain cells. The potential neurotoxic mechanisms of AFB1 and T-2 toxin were discussed by summarizing the relevant research reports from the past ten years. AFB1 and T-2 toxin cause neuronal damage in the cerebral cortex and hippocampus, leading to synaptic transmission dysfunction, ultimately impairing the nervous system function of the body. The toxic mechanism is related to excessive reactive oxygen species (ROS), oxidative stress, mitochondrial dysfunction, apoptosis, autophagy, and an exaggerated inflammatory response. After passing through the blood-brain barrier, toxins can directly affect glial cells, alter the activation state of microglia and astrocytes, thereby promoting brain inflammation, disrupting the blood-brain barrier, and influencing the synaptic transmission process. We discussed the diverse effects of various concentrations of toxins and different modes of exposure on neurotoxicity. In addition, toxins can also cross the placental barrier, causing neurotoxic symptoms in offspring, as demonstrated in various species. Our goal is to uncover the underlying mechanisms of the neurotoxicity of AFB1 and T-2 toxin and to provide insights for future research, including investigating the impact of mycotoxins on interactions between microglia and astrocytes.

Sevoflurane alleviates inflammation, apoptosis and permeability damage of human umbilical vein endothelial cells induced by lipopolysaccharide by inhibiting endoplasmic reticulum stress via upregulating RORα

Endothelial dysfunction often accompanies sepsis. Sevoflurane (Sev) is a widely used inhaled anesthetic that has a protective effect on sepsis-associated damage. We aimed to elucidate the role of Sev in endothelial dysfunction by using a model of LPS induced HUVECs. Sev increased the viability and decreased the apoptosis of HUVECs exposed to LPS. Inflammation and endothelial cell adhesion were improved after Sev addition. Besides, Sev alleviated LPS-induced endothelial cell permeability damage in HUVECs. RORα served as a potential protein that bound to Sev. Importantly, Sev upregulated RORα expression and inhibited endoplasmic reticulum (ER) stress in LPS-treated HUVECs. RORα silencing reversed the impacts of Sev on ER stress. Moreover, RORα deficiency or tunicamycin (ER stress inducer) treatment restored the effects of Sev on the viability, apoptosis, inflammation and endothelial permeability damage of HUVECs exposed to LPS. Taken together, Sev ameliorated LPS-induced endothelial cell damage by targeting RORα to inhibit ER stress.

Microplastics induced endoplasmic reticulum stress to format an inflammation and cell death in hepatocytes of carp (Cyprinus carpio)

Microplastics (MPs) are a serious threat to the living environment of aquatic organisms. However, there are fewer studies on the toxicity of microplastics to freshwater organisms. This study aimed to establish a polystyrene microplastics (PS-MPs) model by feeding carp (Cyprinus carpio) PS-MP (1000 ng/L) particles 8 μm in size. HE staining revealed a mass of inflammatory cells infiltrated in the carp hepatopancreas. The activities of alkaline phosphatase (AKP), aspartate transaminase (AST), lactate dehydrogenase (LDH), and alanine transaminase (ALT) were strengthened considerably, suggesting that PS-MPs cause injury to the hepatopancreas of carp. Real-Time polymerase chain reaction and western blotting results indicated increased levels of glucose-regulated protein 78 (GRP78), (PKR)-like ER kinase (PERK), eukaryotic translation initiation Factor 2α (EIF2α) and activating transcription Factor 4 (ATF4) genes and increased levels of inflammatory factors downstream of endoplasmic reticulum stress (ERs) thioredoxin-interacting protein (TXNIP), NOD-like receptor protein 3 (NLRP3), interleukin-18 (IL-18), interleukin-1β (IL-1β), and caspase 1. Increased expression of microtubule-associated protein-2 (LC3II), autophagy-related 5 (ATG5) and autophagy-related 12 (ATG12) genes revealed that PS-MPs promoted autophagy in carp hepatocytes. The enhanced expression of the Caspase 12, Caspase 3, and Bax genes suggested that PS-MPs led to the apoptosis of carp hepatocytes. These results suggest that PS-MPs result in serious injury to the hepatopancreas of carp. The present study of PS-MPs in freshwater fish from the aspect of endoplasmic reticulum stress was conducted to provide references and suggestions for toxicological studies of PS-MPs in freshwater environments.

Hesperetin protects hippocampal neurons from the neurotoxicity of Aflatoxin B1 in mice

Aflatoxin B1 (AFB1) is a major food and feed pollutant that endangers public health. Previous studies have shown that exposure to AFB1 causes neurotoxicity in the body. However, the mechanism of neurotoxicity caused by AFB1 is not well understood, and finding a workable and practical method to safeguard animals from AFB1 toxicity is essential. This study confirmed that AFB1 caused endoplasmic reticulum stress (ER stress) and apoptosis in hippocampal neurons using C57BL/6 J mice and HT22 cells as models. In vitro experiments showed that the aryl hydrocarbon receptor (AHR) plays a significant role in the cytotoxicity of AFB1. Finally, we assessed how hesperetin protecting against the neurotoxicity caused by AFB1. Our findings demonstrated that AFB1 increased the levels of BAX and Cleaved-Caspase3 proteins, while decreasing the levels of BCL2 protein in the CA1 and CA3 regions of the hippocampus. The AFB1 increased the expression of AHR and activated nuclear translocation. It also elevated the expression levels of Chop, GRP78, p-IRE1/ Xbp1s, and p-PERK/p-EIF2a. Importantly, we also discovered for the first time that blocking AHR in HT22 cells dramatically reduced the level of ER stress and apoptosis caused by AFB1. In vivo and in vitro studies, supplementation of hesperetin effectively reversed AFB1-induced cytotoxicity. We have demonstrated that hesperetin effectively restored the imbalance in the GSH/GST system in HT22 cells treated with AFB1. Furthermore, we observed that elevated GSH levels facilitated the formation of AFB1-GSH complexes, which enhanced the excretion of AFB1. Therefore, hesperetin improves ER stress-induced apoptosis by reducing AFB1 activation of AHR.

Transcriptome analysis reveals the mechanism of the effect of perfluorocaproic acid exposure on brain injury in Carassius auratus

Perfluorocaproic acid (PFHxA) has received much attention as an emerging pollutant linked to neurological problems in humans and fish. However, the potential mechanism remains unknown. In this study, the pathological damage to tissue sections demonstrated that perfluorocaproic acid caused brain tissue damage, and the increased antioxidant index malondialdehyde (MDA) and decrease in superoxide Dismutase (SOD), acid phosphatase (ACP), alkaline phosphatase (AKP), glutathione peroxidase (GSH-Px), Catalase (CAT), and Lysozyme (LZM) that perfluorocaproic acid activated antioxidant stress and caused brain damage. Transcriptome sequencing discovered 1,532 divergent genes, 931 upregulated, and 601 down-regulated. Furthermore, according to GO enrichment analysis, the differently expressed genes were shown to be involved in biological processes, cellular components, and molecular functions. The MAPK, calcium, and Neuroactive ligand-receptor interaction were considerably enriched in the KEGG enrichment analysis. We then analyzed qRT-PCR and chose ten essential differentially expressed genes for validation. The qRT-PCR results followed the same pattern as the RNA-Seq results. In conclusion, our study shows that perfluorocaproic acid exposure causes oxidative stress in the brain. It establishes a theoretical foundation for future research into genes linked to perfluorocaproic acid toxicity.

Aflatoxin B1 triggers apoptosis in rabbit hepatocytes via mediating oxidative stress and switching on the mitochondrial apoptosis pathway

Aflatoxin B1 (AFB1) is considered the most toxic carcinogenic compound, and exposure to AFB1 is highly associated with hepatocellular carcinoma. The aim of this study was to investigate the effects of different doses of AFB1 on growth performance and the liver of rabbits, as well as explore its underlying mechanisms. A total of eighty 30-day-old meat rabbits were randomly divided into four treatments. The control group was fed a pollution-free diet, while the AFL, AFM, and AFH groups were fed contaminated diets containing 13 μg/kg, 19 μg/kg, and 25 μg/kg of AFB1, respectively. The results showed that AFB1 had detrimental effects on the production performance of rabbits, resulting in decreased weight gain. Additionally, AFB1 exposure was associated with increased activity of Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT), as well as decreased levels of total protein (TP) and albumin (ALB) in the serum. AFB1 induced the production of reactive oxygen species (ROS) and malondialdehyde (MDA) while inhibiting the activity of glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) activity in liver tissues. AFB1 decreased the mRNA transcription and protein expression of nuclear factor-erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and NAD(P)H dehydrogenase quinone-1 (NQO-1). AFB1 not only decreased the contents of cytochrome P4501A2 (CYP1A2), cytochrome P4502A6 (CYP2A6) and cytochrome P4503A4 (CYP3A4) but also increased the content of AFB1-DNA adducts in the liver. Furthermore, AFB1 enhanced the expression of cytochrome c (cyt-c), caspase-9, caspase-3, and Bcl-2-associated X protein (Bax), while inhibiting the expression of B-cell lymphoma 2 (Bcl-2). Therefore, we demonstrated that AFB1 triggered apoptosis in rabbit hepatocytes via mediating oxidative stress and switching on the mitochondrial apoptosis pathway, and decreased rabbit performance.

Comparative physiological and transcriptome analysis provide insights into the inhibitory effect of 6-pentyl-2H-pyran-2-one on Clarireedia jacksonii

Clarireedia spp. is a destructive phytopathogenic fungus that causes turf dollar spot of bent-grass, leading to widespread lawn death. In this study, we explored the antifungal capability of 6-pentyl-2H-pyran-2-one (6PP), a natural metabolite volatilized by microorganisms, which plays an important role in the biological control of turfgrass dollar spot. However, the mechanisms by which 6PP inhibits Clarireedia jacksonii remain unknown. In the present study, C. jacksonii mycelial growth was inhibited by the 6PP treatment and the 6PP treatment damaged cell membrane integrity, causing an increase in relative conduc-tivity. Furthermore, physiological and biochemistry assay showed that 6PP treatment can enhance reactive oxygen species (ROS) levels, malondialdehyde (MDA) content obviously increased with 6PP exposure, increased alchohol dehydrogenase (ADH) and depleted acetalde-hyde dehydrogenase (ALDH), and activated the activities of many antioxidant enzymes in C. jacksonii. Gen Ontology and Kyoto Encyclopedia of Genes and Genomes analysis revealed that some genes in C. jacksonii after 6PP treatment related to integrity of the cell wall and membrane, and oxidative stress were significantly downregulated. It is worth mentioning that the fatty acid degradation pathway is significantly upregulated, with an increase in ATP content and ATP synthase activity, which may promote fungal cell apoptosis. Moreover, we found that the expression of ABC transporters, and glutathione metabolism encoding genes were increased to respond to external stimuli. Taken together, these findings revealed the potential antifungal mechanism of 6PP against Clarireedia spp., which also provides a theoretical basis for the commercial utilization of 6PP as a green pesticide in the future.

The molecular mechanisms of alpha-lipoic acid on ameliorating aflatoxin B1-induced liver toxicity and physiological dysfunction in northern snakehead (Channa argus)

This research aimed to evaluate the protective mechanism of alpha-lipoic acid (α-LA) on the food-borne aflatoxin B₁ (AFB₁) exposure-induced liver toxicity and physiological dysfunction in the northern snakehead (Channa argus). 480 fish (9.24±0.01 g) were randomly assigned to four treatment groups and fed with four experimental diets for 56 d including the control group (CON), AFB₁ group (200 ppb AFB₁), 600 α-LA group (600 ppm α-LA+200 ppb AFB₁), and 900 α-LA group (900 ppm α-LA+200 ppb AFB₁). The results revealed that 600 and 900 ppm α-LA attenuated AFB₁-induced growth inhibition and immunosuppression in northern snakehead. 600 ppm α-LA significantly decreased the serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and lactate dehydrogenase levels, and AFB₁ bioaccumulation, and attenuated the changes of hepatic histopathological and ultrastructure induced by AFB₁. Moreover, 600 and 900 ppm α-LA significantly up-regulated phase I metabolism genes (cytochrome P450-1a, 1b, and 3a) mRNA expression, inhibited the levels of malondialdehyde, 8‑hydroxy-2 deoxyguanosine and reactive oxygen species in the liver. Notably, 600 ppm α-LA significantly up-regulated the expression levels of nuclear factor E2 related factor 2 and its related downstream antioxidant molecules (heme oxygenase 1 and NAD(P)H: quinone oxidoreductase 1, etc.), increased the phase II detoxification enzyme-related molecules (glutathione-S-transferase and glutathione), antioxidant parameters (catalase and superoxide dismutase, etc.), and the expressions of Nrf2 and Ho-1 protein in the presence of AFB₁ exposure. Furthermore, 600 and 900 ppm α-LA significantly reduced the characteristic indices of AFB₁-induced endoplasmic reticulum stress (glucose-regulated protein 78 and inositol requiring enzyme 1, etc.), apoptosis (caspase-3 and cytochrome c, etc.) and inflammation (nuclear factor kappa B and tumor necrosis factor α, etc.), while increased the B-cell lymphoma-2 and inhibitor of κBα in the liver after being exposed to AFB₁. To summarize, the above results indicate that dietary α-LA could modulate the Nrf2 signaling pathway to ameliorate AFB₁-induced growth inhibition, liver toxicity, and physiological dysfunction in northern snakehead. Although the concentration of α-LA increased to 900 ppm from 600 ppm, the protective effects of the 900 ppm α-LA do not show an advantage over the 600 ppm α-LA, and even show inferiority in some respects. So that the recommended concentration of α-LA is 600 ppm. The present study provides the theoretical foundation for developing α-LA as the prevention and treatment of AFB₁-induced liver toxicity in aquatic animals.

The protective effects of Saccharomyces cerevisiae on the growth performance, intestinal health, and antioxidative capacity of mullet (Liza ramada) fed diets contaminated with aflatoxin B1

Plant protein ingredients are increasingly included in mullet feeds and are expected to be contaminated with mycotoxins (AFB1). Thus, this study investigated the protective role of Saccharomyces cerevisiae against oxidative stress and hepato-renal malfunction induced by AFB1 contamination in mullets. Four diets were formulated, where the first was kept as the control diet, and the second was supplemented with S. cerevisiae at 5 × 106 cells/g. The third diet was supplied with AFB1 at 1 mg/kg, and the fourth was supplemented with S. cerevisiae and AFB1. Mullet fed the control or both AFB1 and S. cerevisiae (yeast/AFB1) had similar FBW, WG, SGR, and FCR (P˃0.05). Mullet treated with S. cerevisiae without AFB1 contamination showed the highest FBW, WG, and SGR (P<0.05), while fish in the AFB1 group had lower FBW, WG, and SGR and higher FCR than fish in the control and yeast/AFB1 groups (P<0.05). Using yeast with AFB1 prevented pathological hazards and improved intestinal structure. Further, yeast combined with AFB1 reduced the degenerative changes and enhanced the histological structure except for a mild inflammatory reaction around the bile duct. Fish in the control or yeast/AFB1 group had higher HB, PCV, RBCs, and WBCs than fish in the AFB1 group (P<0.05). Fish fed the control, or the yeast/AFB1 diets had similar total protein and albumin levels with higher values than fish contaminated with AFB1 (P<0.05). Fish fed the control and yeast/AFB1 diets had similar ALT, AST, urea, and creatinine levels (P˃0.05) and were lower than fish contaminated with AFB1. Additionally, fish fed the control and yeast/AFB1 diets had similar CAT, GPx, SOD, and MDA (P˃0.05) and were lower than fish contaminated with AFB1 (P<0.05). In conclusion, incorporating S. cerevisiae ameliorated the negative impacts of AFB1 toxicity on mullets’ growth, hepato-renal function, and antioxidative capacity.

Lonp1 and Sig-1R contribute to the counteraction of ursolic acid against ochratoxin A-induced mitochondrial apoptosis

Ochratoxin A (OTA), a secondary fungal metabolite with nephrotoxicity, is widespread in numerous kinds of feeds and foodstuffs. Ursolic acid (UA), a water-insoluble pentacyclic triterpene acid, exists in a wide range of food materials and medicinal plants. Our earlier researches provided preliminary evidence that mitochondria- and mitochondria-associated endoplasmic reticulum membranes (MAMs)-located stress-responsive Lon protease 1 (Lonp1) had a protective function in OTA-induced nephrotoxicity, and the renoprotective function of UA against OTA partially due to Lonp1. However, whether other MAMs-located protiens, such as endoplasmic reticulum stress (ERS)-responsive Sigma 1-type opioid receptor (Sig-1R), contribute to the protection of UA against OTA-induced nephrotoxicity together with Lonp1 needs further investigation. In this study, the cell viability, reactive oxygen species, and protein expressions of human proximal tubule epithelial-originated kidney-2 (HK-2) cells varied with OTA and/or UA/CDDO-me/AVex-73/Sig-1R siRNA treatments were determined. Results indicated that a 24 h-treatment of 5 μM OTA could significantly induce mitochondrial-mediated apoptosis via repressing Lonp1 and Sig-1R, thereby enhancing the protein expressions of GRP78, p-PERK, p-eIF2α, CHOP, IRE1α, and Bax, and inhibiting the protein expression of Bcl-2 in HK-2 cells, which could be remarkably relieved by a 2 h-pre-treatment of 4 μM UA (P < 0.05). In conclusion, through mutual promotion between Lonp1 and Sig-1R, UA could effectively relieve OTA-induced apoptosis in vitro and break the vicious cycle between oxidative stress and ERS, which activated the mitochondrial apoptosis pathway.

Aflatoxin B1 Induced Oxidative Stress and Gut Microbiota Disorder to Increase the Infection of Cyprinid Herpesvirus 2 in Gibel Carp (Carassius auratus gibelio)

Aflatoxin contamination of food and water is a serious problem worldwide. This study investigated the defensive ability of gibel carp exposed to aflatoxin B1 (AFB1) by challenging it with cyprinid herpesvirus 2 (CyHV-2) infection. The data showed that AFB1 exposure significantly increased the mortality of CyHV-2-infected gibel carp, and enhanced the viral load in the fish liver, kidney, and spleen. The oxidative-antioxidant balance suggested that AFB1 induced severe oxidative stress, including increased reactive oxygen species (ROS) and malondialdehyde (MDA) levels in the AFB1 exposed group, and the reduced activity of superoxide dismutase (SOD), glutathione-S-transferase (GST) and catalase (CAT) in the AFB1 exposed group. Meanwhile, the related expression of nuclear factor erythroid 2-related factor 2 (Nrf2), interferon regulatory factor 3 (IRF3) and the type 1 interferon (IFN1) were noticeably down-regulated, but caspase-1 was up-regulated, after exposure to AFB1, demonstrating that fish are unable to avoid the virus infection. It should be noted that the intestinal microbiota diversity and richness were lower in the AFB1 exposed group, and the composition of intestinal microbiota was affected by AFB1, resulting in the higher abundance of bacteria (such as Aeromonas and Bacteroides) and the lower abundance of potentially beneficial bacteria (such as Cetobacterium and Clostridium) in the AFB1 exposed group. This research provides insight into the possibility that AFB1 may increase the susceptibility of C. gibelio to CyHV-2 infection, and thus amplify the viral outbreak to endanger ecological safety in aquatic environment.