Larval zebrafish as an in vitro model for evaluating toxicological effects of mycotoxins

The spatiotemporal and paradoxical roles of NRF2 in renal toxicity and kidney diseases

Over 10% of the global population is at risk to kidney disorders. Nuclear factor erythroid-derived 2-related factor 2 (NRF2), a pivotal regulator of redox homeostasis, orchestrates antioxidant response that effectively counters oxidative stress and inflammatory response in a variety of acute pathophysiological conditions, including acute kidney injury (AKI) and early stage of renal toxicity. However, if persistently activated, NRF2-induced transcriptional cascade may disrupt normal cell signaling and contribute to numerous chronic pathogenic processes such as fibrosis. In this concise review, we assembled experimental evidence to reveal the cell- and pathophysiological condition-specific roles of NRF2 in renal chemical toxicity, AKI, and chronic kidney disease (CKD), all of which are closely associated with oxidative stress and inflammation. By incorporating pertinent research findings on NRF2 activators, we dissected the spatiotemporal roles of NRF2 in distinct nephrotoxic settings and kidney diseases. Herein, NRF2 exhibits diverse expression patterns and downstream gene profiles across distinct kidney regions and cell types, and during specific phases of nephropathic progression. These changes are directly or indirectly connected to altered antioxidant defense, damage repair, inflammatory response, regulated cell death and fibrogenesis, culminating ultimately in either protective or deleterious outcomes. The spatiotemporal and paradoxical characteristics of NRF2 in mitigating nephrotoxicity suggest that translational application of NRF2 activation strategy for prevention and interventions of kidney injury are unlikely to be straightforward - right timing and spatial precision must be taken into consideration.

Developmental and neurotoxic effects of dimethyl phthalate on zebrafish embryos and larvae

Dimethyl phthalate (DMP) has been extensively utilized as a plasticizer on a global scale for many years. Its presence in the environment and its harmful effects on living organisms have raised concerns. This study aimed to examine its potential developmental neurotoxicity by utilizing zebrafish as a model. Zebrafish embryos were exposed to different concentrations of DMP (5-100 mg/L) from 4 to 120 h post-fertilization (hpf). The survival, hatching, and malformation rates were recorded for each group. Behavioral analysis was conducted on zebrafish larvae, and transgenic zebrafish Tg(elavl3:EGFP) were used to assess the impact of DMP on neuronal cells. The mRNA levels of key neurological marker genes were evaluated at 96 hpf of DMP exposure. The study revealed that exposure to DMP resulted in decreased survival and hatching rates in zebrafish. Embryos treated with 50 mg/L of DMP exhibited lower average survival rates (72.78-78.33%) between 24-96 hpf, while treatment with 25-50 mg/L of DMP resulted in reduced hatching rates (39.44% and 2.22%, respectively) at 48 hpf compared to the control group. Moreover, exposure to 25-50 mg/L of DMP caused an increase in malformations, such as tail curvature, spinal curvature, yolk sac edema and pericardial edema. Interestingly, at 24 hpf, DMP also resulted in an increase in spontaneous tail coiling in zebrafish embryos, as well as a decrease in their swimming distance at 120 hpf. Furthermore, treatment with 50 mg/L of DMP led to a decrease in the fluorescence intensity of transgenic zebrafish Tg(elavl3: EGFP). RT-qPCR analysis showed a significant down-regulation of marker genes (gap43, mbp, α1-tubulin, syn2a) associated with nervous system function in DMP-treated zebrafish. Overall, these findings offer a thorough understanding of the mechanisms underlying the neurotoxicity caused by DMP, highlighting the risk of DMP on developmental and neurotoxic effects in zebrafish. Therefore, strict supervision of DMP use and release is essential to safeguard ecological and aquatic organisms.

High-Resolution Magic-Angle Spinning Nuclear Magnetic Resonance Identifies Impairment of Metabolism by T-2 Toxin, in Relation to Toxicity, in Zebrafish Embryo Model

Among the widespread trichothecene mycotoxins, T-2 toxin is considered the most toxic congener. In the present study, we utilized high-resolution magic-angle spinning nuclear magnetic resonance (HRMAS NMR), coupled to the zebrafish (Danio rerio) embryo model, as a toxicometabolomics approach to elucidate the cellular, molecular and biochemical pathways associated with T-2 toxicity. Aligned with previous studies in the zebrafish embryo model, exposure to T-2 toxin was lethal in the high parts-per-billion (ppb) range, with a median lethal concentration (LC50) of 105 ppb. Exposure to the toxins was, furthermore, associated with system-specific alterations in the production of reactive oxygen species (ROS), including decreased ROS production in the liver and increased ROS in the brain region, in the exposed embryos. Moreover, metabolic profiling based on HRMAS NMR revealed the modulation of numerous, interrelated metabolites, specifically including those associated with (1) phase I and II detoxification, and antioxidant pathways; (2) disruption of the phosphocholine lipids of cell membranes; (3) mitochondrial energy metabolism, including apparent disruption of the tricarboxylic acid (TCA) cycle, and the electron transport chain of oxidative phosphorylation, as well as "upstream" effects on carbohydrate, i.e., glucose metabolism; and (4) several compensatory catabolic pathways. Taken together, these observations enabled development of an integrated, system-level model of T-2 toxicity in relation to human and animal health.

Comparative Assessment of Beeswax Alcohol and Coenzyme Q10 (CoQ10) to Prevent Liver Aging, Organ Damage, and Oxidative Stress in Hyperlipidemic Zebrafish Exposed to D-Galactose: A 12-Week Dietary Intervention

The current study was designed to compare in vivo efficacy between beeswax alcohol (BWA) and coenzyme Q10 (CoQ10) to treat fatty liver changes, oxidative stress, and damages in major organs of zebrafish by 12 weeks with high-cholesterol (HC) and galactose (Gal) supplementation. At week 12, the HC control and HC+Gal control groups showed 96% and 92% survivability, respectively, while co-supplementation of the 0.5% BWA and 1.0% BWA groups exhibited 96% and 100% survivability. However, co-supplementation of the 0.5% CoQ10 and 1.0% CoQ10 groups revealed the lowest survivability, around 92% and 89%, respectively. The 0.5% BWA and 1.0% BWA groups showed 21% (p < 0.001) and 41% (p < 0.001), respectively, lower total cholesterol (TC) than the HC+Gal control, while the 1.0% CoQ10 group showed only 15% lower TC than the control. Interestingly, the 0.5% BWA and 1.0% BWA groups showed 22% (p < 0.001) and 38% (p < 0.001), respectively, lower triglyceride (TG) than the HC+Gal control. However, both the 0.5% CoQ10 and 1.0% CoQ10 groups showed similar TG levels as the control, suggesting that CoQ10 supplementation had no effect on lowering serum TG. The 1.0% BWA group showed the highest plasma HDL-C and HDL-C/TC (%) up to 3.2-fold and 5.5-fold, respectively, higher than those of the HC+Gal control, while the 1.0% CoQ10 group showed 2.4-fold and 2.8-fold higher plasma HDL-C and HDL-C/TC (%), respectively, than the control. The plasma aspartate transaminase (AST) and alanine transaminase (ALT) levels were lowest in the 1.0% BWA group, 51% and 72%, respectively, lower than HC+Gal control, suggesting the lowest extent of hepatic damage. In hepatic tissue, neutrophil infiltration and interleukin (IL)-6 production were the lowest in the 1.0% BWA group, around 67% and 85%, respectively, lower than the HC+Gal control. Fatty liver change, cellular apoptosis, and cell senescence in hepatic tissue were remarkably lowered in the 1.0% BWA group, while the CoQ10 group showed much less effect than the BWA group. In kidney, ovary, and testis tissue, the 1.0% BWA group showed the lowest production of reactive oxygen species, the extent of cellular senescence, and cellular apoptosis with the healthiest cell morphology. In conclusion, supplementation of BWA remarkably protected the liver, kidney, ovary, and testis from oxidative damage by cholesterol and galactose consumption, with the least serum AST and ALT levels, inflammatory parameters, and senescence markers.

Enhancing Wound Healing and Anti-Inflammatory Effects by Combination of CIGB-258 and Apolipoprotein A-I against Carboxymethyllysine Toxicity in Zebrafish: Insights into Structural Stabilization and Antioxidant Properties

CIGB-258 is known to exert anti-inflammatory activity via structural stabilization of apolipoprotein A-I (apoA-I) and functional enhancement of high-density lipoproteins (HDL) against acute toxicity of carboxymethyllysine (CML). The co-presence of CIGB-258 in reconstituted HDL (rHDL) formed larger rHDL particles and enhanced anti-inflammatory activity in a dose-dependent manner of apoA-I:CIGB-258, 1:0, 1:0.1, 1:0.5, and 1:1 of molar ratio, in the synthesis of the rHDL. However, no study has evaluated the enhancement of HDL functionality by the co-presence of lipid-free apoA-I and CIGB-258. The present study was therefore designed to compare the structural stabilization and functional improvement of HDL in the presence of lipid-free apoA-I and CIGB-258 in molar ratios of 1:0, 1:0.1, 1:0.5, and 1:1 within both HDL2 and HDL3. As the concentration of CIGB-258 increased, it effectively inhibited the cupric-ion-induced oxidation of HDL, thereby safeguarding apoA-I from proteolytic degradation. Additionally, the wound-healing activity of zebrafish was significantly (p < 0.01) enhanced by the co-addition of apoA-I:CIGB-258 (1:1) up to 1.6-fold higher than apoA-I alone (1:0) under the presence of CML. ApoA-I:CIGB-258 (1:1) treatment exhibited the lowest apoptosis and production of reactive oxygen species against CML-induced damage in the wound site. Also, an increase in wounded tissue granulation and epidermis thickness was observed with increasing concentration of CIGB-258 during 48 h post-treatment via the healing process. Intraperitoneal injection of apoA-I:CIGB-258 mixture remarkably ameliorated the acute paralysis and restored zebrafish swimming ability impaired by the acute toxicity of CML. The increase of CIGB-258 content, especially co-injection of apoA-I:CIGB-258 (1:1), leads to a significant 2.3-fold (p < 0.001) and 4.1-fold (p < 0.001) higher zebrafish survivability and recovery of swimming ability, respectively, than those of CML-control. In the apoA-I:CIGB-258 (1:1) group, neutrophil infiltration and interleukin (IL)-6 production was lowest in the hepatic tissue with the least cellular damage and apoptosis. Additionally, the group treated with apoA-I:CIGB-258 (1:1) demonstrated the lowest plasma levels of total cholesterol (TC) and triglycerides (TG), along with minimal damage to the kidney, ovary, and testicular cells. Conclusively, co-treatment of CIGB-258 with apoA-I effectively mitigated acute inflammation in zebrafish, safeguarded vital organs, structurally stabilized apoA-I, and enhanced HDL functionality.

Comparison of the In Vivo Efficacy of Cuban (Raydel®) and Chinese (BOC Science) Policosanol in Alleviating Dyslipidemia and Inflammation via Safeguarding Major Organs and Reproductive Health in Hyperlipidemic Zebrafish: A Twelve-Week Consumption Study

Policosanol is a blend of long-chain aliphatic alcohols (LCAAs) and is well-known for several health-beneficial activities; however, the functionality of policosanol varied substantially based on the composition of LCAAs. In this study, two distinct policosanols, Raydel® (extracted from Cuban sugarcane wax) and BOC Sciences (extracted from Chinese sugarcane wax), were dietarily supplemented (0.1% w/w) for 12 weeks in hyperlipidemic zebrafish to examine their influence on the blood lipid profile and functionality of the liver, kidney, and reproductive organs. The results demonstrated a noteworthy impact of both policosanols on preventing high-cholesterol diet (HCD, 4% w/w)-induced dyslipidemia by decreasing total cholesterol (TC) and triglyceride (TG) levels in the plasma. However, compared to BOC Sciences, the Raydel® policosanol exhibited a significantly (p < 0.05) higher efficacy in reducing HCD-induced TC and TG levels. A substantial effect was observed exclusively with the Raydel® policosanol in mitigating HCD-impaired low-density-lipoprotein cholesterol (LDL-C) and high-density-lipoprotein cholesterol (HDL-C) levels. Hepatic histology and immunohistochemistry (IHC) analysis revealed the higher efficacy of Raydel® policosanol over BOC Sciences policosanol to prevent HCD-provoked fatty liver changes, cellular senescence, oxidative stress, and interleukin (IL)-6 production. Consistently, a significantly higher effect of Raydel® over BOC Sciences policosanol was observed on the protection of kidney, testis, and ovary morphology hampered by HCD consumption. In addition, Raydel® policosanol exhibited a notably stronger effect (~2-fold, p < 0.05) on the egg-laying ability of the zebrafish compared to policosanol from BOC Sciences. Furthermore, Raydel® policosanol plays a crucial role in improving embryo viability and mitigating developmental defects caused by the intake of an HCD. Conclusively, Raydel® policosanol displayed a substantially higher efficacy over BOC Sciences policosanol to revert HCD-induced dyslipidemia, the functionality of vital organs, and the reproductive health of zebrafish.

Mechanistic insights into the parental co-exposure of T-2 toxin and epoxiconazole on the F1 generation of zebrafish (Danio rerio)

Mycotoxins and pesticides frequently coexist in agricultural commodities on a global scale. The potential transgenerational consequences induced by these substances pose a significant threat to human health. However, there is a lack of data concerning the effects of co-contamination by these chemicals in the F1 generation following parental exposure. This investigation delved into the mixture effects of T-2 toxin (T-2) and epoxiconazole (EPO) on the offspring of zebrafish (Danio rerio). The findings revealed that exposure across generations to a combination of T-2 and EPO resulted in toxicity in the larvae of the F1 generation. This was demonstrated by a significant increase in the levels or activities of malondialdehyde (MDA), thyroxine (T4), Caspase3, and cas9, along with a decrease in the levels of cyp19a, ERα, and ERβ. These outcomes suggested that cross-generational exposure to T-2 and EPO in D. rerio disrupted oxidative balance, induced cell apoptosis, and affected the endocrine system. Moreover, these effects were magnified when the F1 generation was continuously exposed to these compounds. Notably, these adverse effects could persist in subsequent generations without additional exposure. This study underscored the potential dangers associated with the simultaneous presence of T-2 and EPO on the development of fish offspring and the resulting environmental hazards to aquatic ecosystems. These findings emphasized the significant health risks posed by cross-generational exposure and highlighted the need for additional legislative measures to address these concerns.

Thermo-Alkali-Tolerant Recombinant Laccase from Bacillus swezeyi and Its Degradation Potential against Zearalenone and Aflatoxin B1

The enzymatic biodegradation of mycotoxins in food and feed has attracted the most interest in recent years. In this paper, the laccase gene from Bacillus swezeyi was cloned and expressed in Escherichia coli BL 21(D3). The sequence analysis indicated that the gene consisted of 1533 bp. The purified B. swezeyi laccase was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis -12% with an estimated molecular weight of 56.7 kDa. The enzyme is thermo-alkali-tolerant, displaying the optimal degradation of zearalenone (ZEN) and aflatoxin B1 (AFB1) at pH 8 and 9, with incubation temperatures of 55 and 50 °C, respectively, within 24 h. The degradation potentials of the 50 μg of the enzyme against ZEN (5.0 μg/mL) and AFB1 (2.5 μg/mL) were 99.60 and 96.73%, respectively, within 24 h. To the best of our knowledge, this is the first study revealing the recombinant production of laccase from B. swezeyi, its biochemical properties, and potential use in ZEN and AFB1 degradation in vitro and in vivo.

Beauvericin and enniatin B mycotoxins alter aquatic ecosystems: Effects on green algae

Myxotoxins can contaminate algal-based products and arrive to the food chain to consumers producing chronic toxicity effects. Here, we studied phytotoxicity of mycotoxins, beauvericin (BEA) and ennaitin B (ENN B) in four phytoplankton strains: Acutodesmus sp., Chlamydomonas reinhardtii, Haematococcus pluvialis, and Monoraphidium griffithii, which are all green algae. It was tested the capacity of clearing the media of BEA and ENN B at different concentrations by comparing nominal and measured quantifications. Results revealed that Acutodesmus sp. and C. reinhardtii tended to flow up and down growth rate without reaching values below 50% or 60%, respectively. On the other hand, for H. pluvialis and M. griffith, IC50 values were reached. Regarding the clearance of media, in individual treatment a decrease of the quantified mycotoxin between nominal and measured values was observed; while in binary treatment, differences among both values were higher and more noted for BEA than for ENN B.

Consumption of Policosanol (Raydel®) Improves Hepatic, Renal, and Reproductive Functions in Zebrafish: In Vivo Comparison Study among Cuban, Chinese, and American Policosanol

The current study compared three policosanols from Cuba (sugarcane, Raydel®, policosanol (1), China (rice bran, Shaanxi, policosanol (2), and the USA (sugarcane, Lesstanol®, policosanol (3) in the treatment of dyslipidemia and protection of the liver, ovary, and testis in hypercholesterolemic zebrafish. After twelve weeks of supplementation of each policosanol (PCO, final 0.1% in diet, w/w) with a high cholesterol diet (HCD, final 4%, w/w), the Raydel policosanol (PCO1) group showed the highest survivability, approximately 89%. In contrast, Shaanxi policosanol (PCO2) and Lesstanol policosanol (PCO3) produced 73% and 87% survivability, respectively, while the HCD alone group showed 75% survivability. In the 12th week, the PCO1 group demonstrated the most modest increase in body weight along with significantly lower levels of total cholesterol (TC) and triglycerides (TG) in comparison to the HCD control group. Additionally, the PCO1 group exhibited the highest proportion of high-density lipoprotein (HDL)-cholesterol within TC. Notably, the PCO1 group displayed the lowest level of aspartate aminotransferase and alanine aminotransferase, minimal infiltration of inflammatory cells, reduced interleukin (IL)-6 production in the liver, a notable decline in reactive oxygen species (ROS) generation and mitigated fatty liver changes. HCD supplementation induced impairment of kidney morphology with the greatest extent of ROS production and apoptosis. On the other hand, the PCO 1 group showed a remarkably improved morphology with the least ROS generation and apoptosis. Within the ovarian context, the PCO1 group exhibited the most substantial presence of mature vitellogenic oocytes, accompanied by minimal levels of ROS and apoptosis. Similarly, in the testicular domain, the PCO1 group showcased optimal morphology for spermatogenesis, characterized by the least interstitial area and diminished production of ROS in testicular cells. At week 8, the PCO1 group showed the highest egg-laying ability, with around 244 eggs produced per mating. In contrast, the HCD alone, PCO2, and PCO3 groups showed significantly lower egg-laying ability (49, 59, and 86 eggs, respectively). The embryos from the PCO1 group exhibited the highest survivability with the fastest swimming ability and developmental speed. These results suggest that PCO1 consumption significantly enhanced the reproduction system, egg-laying ability, and embryo survivability. In conclusion, among the three policosanols, Cuban (Raydel®) policosanol had the strongest effect on survivability, improving dyslipidemia, liver protection, kidney, ovary, and testis with a restoration of the cell morphology, and the least ROS production and apoptosis-induced by HCD supplementation.

Comparison of ZnO doped different phases TiO2 nanoparticles in terms of toxicity using zebrafish (Danio rerio)

Titanium dioxide is used in many commercial and industrial areas such as paint, paper, cosmetics, textiles, and surface coating. The reasons for its use in such a wide area are its anti-corrosion and high stability. Although TiO₂ is considered to be a low-toxicity material, research has been further expanded following the recognition of the possible carcinogenic effects of TiO₂ in humans by the International Agency for Research on Cancer (IARC). The aim of this study is to compare the toxicity of TiO₂ used in many fields in different phases. In the study anatase TiO₂ synthesized by hydrothermal method and dual phase TiO₂ (anatase and rutile phase) structures obtained by thermal conditioning were used and compared with commercially available TiO₂. ZnO which has similar uses like TiO₂ was also used and compared with 1% doped TiO₂ in different phases in terms of toxicity. Zebrafish (Danio rerio, D. rerio), a freshwater fish, which is widely used in toxicity assessments was preferred in this study due to its small size, fast reproduction rate, low cost, physiological and molecular similarity with humans, and genetic predisposition. Experimental investigations showed that the highest death occurred in the low concentrations of (10 ppm) ZnO doped rutile phase. 39% of the embryos died in the ZnO nanoparticle solutions prepared at low concentrations. The highest mortality at medium (100 ppm) and high (1000 ppm) concentrations were observed in the ZnO-doped rutile phase after 96 h. Similarly, the highest malformation was detected in the ZnO-doped rutile phase during the same period.

Interaction of Fumonisin B1, N-Palmitoyl-Fumonisin B1, 5-O-Palmitoyl-Fumonisin B1, and Fumonisin B4 Mycotoxins with Human Serum Albumin and Their Toxic Impacts on Zebrafish Embryos

Fumonisins are frequent food contaminants. The high exposure to fumonisins can cause harmful effects in humans and animals. Fumonisin B1 (FB1) is the most typical member of this group; however, the occurrence of several other derivatives has been reported. Acylated metabolites of FB1 have also been described as possible food contaminants, and the very limited data available suggest their significantly higher toxicity compared to FB1. Furthermore, the physicochemical and toxicokinetic properties (e.g., albumin binding) of acyl-FB1 derivatives may show large differences compared to the parent mycotoxin. Therefore, we tested the interactions of FB1, N-palmitoyl-FB1 (N-pal-FB1), 5-O-palmitoyl-FB1 (5-O-pal-FB1), and fumonisin B4 (FB4) with human serum albumin as well as the toxic effects of these mycotoxins on zebrafish embryos were examined. Based on our results, the most important observations and conclusions are the following: (1) FB1 and FB4 bind to albumin with low affinity, while palmitoyl-FB1 derivatives form highly stable complexes with the protein. (2) N-pal-FB1 and 5-O-pal-FB1 likely occupy more high-affinity binding sites on albumin. (3) Among the mycotoxins tested, N-pal-FB1 showed the most toxic effects on zebrafish, followed by 5-O-pal-FB1, FB4, and FB1. (4) Our study provides the first in vivo toxicity data regarding N-pal-FB1, 5-O-pal-FB1, and FB4.

Ochratoxin A induces locomotor impairment and oxidative imbalance in adult zebrafish

Ochratoxin A (OTA) is a mycotoxin produced by species of filamentous fungi widely found as a contaminant in food and with high toxic potential. Studies have shown that this toxin causes kidney and liver damage; however, data on the central nervous system effects of exposure to OTA are still scarce. Thus, this study aimed to investigate the effects of exposure to OTA on behavioral and neurochemical parameters in adult zebrafish. The animals were treated with different doses of OTA (1.38, 2.77, and 5.53 mg/kg) with intraperitoneal injections and submitted to behavioral evaluations in the open tank and social interaction tests. Subsequently, they were euthanized, and the brains were used to assess markers associated with oxidative status. In the open tank test, OTA altered distance traveled, absolute turn angle, mean speed, and freezing time. However, no significant effects were observed in the social interaction test. Moreover, OTA also increased glutathione peroxidase (GPx), glutathione-S-transferase (GST), and glutathione reductase (GR) levels and decreased non-protein thiols (NPSH) levels in the zebrafish brain. This study showed that OTA can affect behavior and neurochemical levels in zebrafish.

Alterations in Daphnia magna exposed to enniatin B and beauvericin provide additional value as environmental indicators

Mycotoxins beauvericin (BEA) and enniatin B (ENN B) affect negatively several systems and demand more studies as the mechanisms are still unclear. The simultaneous presence of contaminants in the environment manifests consequences of exposure for both animals and flora. Daphnia magna is considered an ideal invertebrate to detect effects of toxic compounds and environmental alterations. In this study, the potential toxicity and the basic mechanism of BEA and ENN B individually and combined were studied in D. magna. Acute and delayed toxicity were evaluated, and transcript levels of genes involved in xenobiotic metabolism (mox, gst, abcb1, and abcc5), reproduction, and oxidative stress (vtg-SOD) were analyzed by qPCR. Though no acute toxicity was found, results revealed a spinning around and circular profile of swimming, a strong decrease of survival after 72 h for BEA and ENN B at 16 µM and 6.25 µM, respectively, while for BEA + ENN B [8 + 1.6] µM after 96 h. The amount of mycotoxin remaining in the media revealed that the higher the concentration assayed the higher the amount remaining in the media. Differential regulation of genes suggests that xenobiotic metabolism is affected denoting different effects on transcription for tested mycotoxins. The results provide new insights into the underlying risk assessment of BEA and ENN B not only through food for consumers but also for the environment.

Morphological and behavioral alterations in zebrafish larvae after exposure to contaminated river sediments collected in different weather conditions

Wastewater treatment plants (WWTPs) are the primary source of micropollutants in aquatic ecosystems. Many micropollutants tend to bind to sediments and persist until remobilizion by bioturbation or flood events. Advanced effluent treatment by ozonation has been proven to eliminate most micropollutants. The present study characterizes sediments' toxic potential regarding zebrafish embryo development, which highly complex nervous system is vulnerable to exposure to neurotoxic substances. Furthermore, behavioral changes can be induced even at low pollutant concentrations and do not cause acute toxicity. The study area includes stretches of the main waterbody, the Wurm River (sampling sites W1-W5), and its tributary the Haarbach River (sampling sites H1, and H2) in North-Rhine Westphalia, Germany. Both waterbodies serve as recipients of WWTPs' effluents. The effluent entering the Haarbach River is conventionally treated, while the Wurm River receives ozonated effluent from the Aachen-Soers WWTP. Seven sampling sites up- and downstream of the WWTPs were investigated in June of two subsequent years. The first sampling campaign in 2017 was characterized by prolonged dry weather. The second sampling campaign in 2018 occurred after prolonged rain events and the release of the rainwater overflow basin. Direct exposure of zebrafish embryos to native sediments using the sediment contact test represented an ecologically realistic scenario and showed no acute sublethal effects. Exposure of the zebrafish embryo to freeze-dried sediments representing the ecotoxicological status of sediments during flood events unfolded acute sublethal toxicity. Behavioral studies with zebrafish larvae were an essential part of environmental neurotoxicity testing. Zebrafish larvae exposed to sediments' concentrations causing no acute effects led to behavioral changes signalizing neurotoxic substances in sediments. Polyaromatic hydrocarbons, polychlorinated biphenyls, and nitroaromatic compounds were identified as potential toxicity drivers, whereby the rainwater overflow basin served as a possible source of pollution. Mixture toxicity, effect-directed analysis, and further sediment monitoring are needed.

Lactobacillus plantarum and Deoxynivalenol Detoxification: A Concise Review

ABSTRACT

Mycotoxins are toxic secondary fungal metabolites that contaminate feeds, and their levels remain stable during feed processing. The economic impact of mycotoxins on animal production happens mainly due to losses related to direct effects on animal health and trade losses related to grain rejection. Deoxynivalenol (DON) is a trichothecene mycotoxin that has contaminated approximately 60% of the grains worldwide. Ingestion of DON induces many toxic effects on human and animal health. Detoxification strategies to decrease DON levels in food and feeds include physical and chemical methods; however, they are not very effective when incorporated into the industrial production process. A valuable alternative to achieve this aim is the use of lactic acid bacteria. These bacteria can control fungal growth and thus overcome DON production or can detoxify the mycotoxin through adsorption and biotransformation. Some Lactobacillus spp. strains, such as Lactobacillus plantarum, have demonstrated preventive effects against DON toxicity in poultry and swine. This beneficial effect is associated with a binding capacity of lactic acid bacteria cell wall peptidoglycan with mycotoxins. Moreover, several antifungal compounds have been isolated from L. plantarum supernatants, including lactic, acetic, caproic, phenyl lactic, 3-hydroxylated fatty, and cyclic dipeptide acids. Biotransformation of DON by L. plantarum into other products is also hypothesized, but the mechanism remains unknown. In this concise review, we highlight the use of L. plantarum as an alternative approach to reduce DON levels and toxicity. Although the action mechanism of L. plantarum is still not fully understood, these bacteria are a safe, efficient, and low-cost strategy to reduce economic losses from mycotoxin contamination cases.

HIGHLIGHTS

Stressful Effects of T-2 Metabolites and Defense Capability of HepG2 Cells

The T-2 toxin (T-2), a mycotoxin produced by several species of Fusarium which belongs to group A of trichothecenes, is rapidly metabolized, and its main metabolites are HT-2, Neosolaniol (Neo), T2-triol and T2-tetraol. In this work, the antioxidant defense system of HepG2 cells against oxidative stress induced by T-2 and its metabolites was evaluated. The results obtained demonstrated that there is an overall decrease in glutathione (GSH) levels after all mycotoxins exposure. Moreover, the GSH levels and the enzymatic activities related to GSH (GPx and GST) increased with NAC pre-treatment (glutathione precursor) and decreased with BSO pre-treatment (glutathione inhibitor). The GPx activity is increased by T2-tetraol. The GST activity increased after T-2 and T2-triol exposure; however, T2-tetraol decreased its activity. Furthermore, CAT activity increased after T-2 and T2-triol; nevertheless, Neo decreased its activity. Finally, SOD activity is increased by all mycotoxins, except after T-2 exposure. So, the damage associated with oxidative stress by T-2 and its metabolites is relieved by the antioxidant enzymes system on HepG2 cells.

Neurotoxicity of mycotoxin citrinin: Novel evidence in developing zebrafish and underlying mechanisms in human neuron cells

Citrinin (CTN) is a mycotoxin that is found as a contaminant in various types of food/feed grains and fermented food supplements. Previous studies have already established the nephrotoxicity and hepatotoxicity of CTN, but the neurotoxicity of CTN has not been clearly examined. In this study, CTN at 2-20 μM was first found to interfere with the neural ganglia formation and locomotive behavior of embryonic zebrafish, a vertebrate animal model, at 24 hpf and 6 dpf, respectively. Further exposure of human neuroblastoma SH-SY5Y cells to 10 and 20 μM CTN for 72 h indicated that pathways responsible for neuron differentiation and projection guidance were down-regulated while oxidative stress and electron transport chain pathways were up-regulated based on the enrichment results of GSEA in the transcriptomic profiling. PCR analysis verified that CTN significantly down-regulated the expression of marker genes involved in neuron differentiation and synaptic signaling. CTN at the doses impairing cellular neurite outgrowth did not trigger mitochondrial oxidative stress and dysfunction. The neurotoxic mechanisms of CTN provide new information that is valuable in the assessment of CTN-related health risk for the general public.

Toxic Effects of Silver Ions on Early Developing Zebrafish Embryos Distinguished from Silver Nanoparticles

Currently, effects of nanomaterials and their ions, such as silver nanoparticles (Ag NPs) and silver ions (Ag+), on living organisms are not yet fully understood. One of the vital questions is whether nanomaterials have distinctive effects on living organisms from any other conventional chemicals (e.g., their ions), owing to their unique physicochemical properties. Due to various experimental protocols, studies of this crucial question have been inconclusive, which hinders rational design of effective regulatory guidelines for safely handling NPs. In this study, we chronically exposed early developing zebrafish embryos (cleavage-stage, 2 hours post-fertilization, hpf) to a dilution series of Ag+ (0-1.2 μM) in egg water (1 mM NaCl, solubility of Ag+ = 0.18 μM) until 120 hpf. We systematically investigated effects of Ag+ on developing embryos and compared them with our previous studies of effects of purified Ag NPs on developing embryos. We found the concentration- and time-dependent effects of Ag+ on embryonic development, and only half of the embryos developed normally after being exposed to 0.25 μM (27 μg/L) Ag+ until 120 hpf. As the Ag+ concentration increases, the number of embryos that developed normally decreases, while the number of embryos that became dead increases. The number of abnormally developing embryos increases as the Ag+ concentration increases from 0 to 0.3 μM and then decreases as the concentration increases from 0.3 to 1.2 μM because the number of embryos that became dead increases. The concentration-dependent phenotypes were observed, showing fin fold abnormality, tail and spinal cord flexure, and yolk sac edema at low Ag+ concentrations (≤0.2 μM) and head and eye abnormalities along with fin fold abnormality, tail and spinal cord flexure, and yolk sac edema at high concentrations (≥0.3 μM). Severities of phenotypes and the number of abnormally developing embryos were far less than those observed in Ag NPs. The results also show concentration-dependent effects on heart rates and hatching rates of developing embryos, attributing to the dose-dependent abnormally developing embryos. In summary, the results show that Ag+ and Ag NPs have distinctive toxic effects on early developing embryos, and toxic effects of Ag+ are far less severe than those of Ag NPs, which further demonstrates that the toxicity of Ag NPs toward embryonic development is attributed to the NPs themselves and their unique physicochemical properties but not the release of Ag+ from the Ag NPs.

Recent advances in the highly sensitive determination of zearalenone residues in water and environmental resources with electrochemical biosensors

Zearalenone (ZEN), a significant class of mycotoxin which is considered as a xenoestrogen, permits, similar to natural estrogens, it's binding to the receptors of estrogen resulting in various reproductive diseases especially, hormonal misbalance. ZEN has toxic effects on human and animal health as a result of its teratogenicity, carcinogenicity, mutagenicity, nephrotoxicity, genotoxicity, and immunotoxicity. To ensure water and environmental resources safety, precise, rapid, sensitive, and reliable analytical and conventional methods can be progressed for the determination of toxins such as ZEN. Different selective nanomaterial-based compounds are used in conjunction with different analytical detection approaches to achieve this goal. The current review demonstrates the state-of-the-art advances of nanomaterial-based electrochemical sensing assays including various sensing, apta-sensing and, immunosensing studies to the highly sensitive determination of various ZEN families. At first, a concise study of the occurrence, structure, toxicity, legislations, and distribution of ZEN in monitoring has been performed. Then, different conventional and clinical techniques and procedures to sensitive and selective sensing techniques have been reviewed and the efficient comparison of them has been thoroughly discussed. This study has also summarized the salient features and the requirements for applying various sensing and biosensing platforms and diverse immobilization techniques in ZEN detection. Finally, we have defined the performance of several electrochemical sensors applying diverse recognition elements couples with nanomaterials fabricated using various recognition elements coupled with nanomaterials (metal NPs, metal oxide nanoparticles (NPs), graphene, and CNT) the issues limiting development, and the forthcoming tasks in successful construction with the applied nanomaterials.

Variations of enzymatic activity and gene expression in zebrafish (Danio rerio) embryos co-exposed to zearalenone and fumonisin B1

The natural co-occurrence of multiple mycotoxins has been reported in cereals and cereal products worldwide. Even though the dietary exposure to mycotoxins constitutes a serious human health, most reports are limited to the toxic effect of individual mycotoxins. The purpose of the present study was to assess the combined toxic effects of zearalenone (ZEN) and fumonisin B1 (FB1) and the potential interaction of their mixture on zebrafish (Danio rerio) embryos. Our results showed that ZEN possessed the higher toxicity to embryonic zebrafish (7-day LC₅₀ value of 0.78 mg a.i. L^-1) compared with FB1 (7-day LC₅₀ value of 227.7 mg a.i. L^-1). The combination of ZEN and FB1 exerted an additive effect on zebrafish embryos. Meanwhile, the activities of antioxidant CAT, caspase-3, and detoxification enzyme CYP450, as well as the expressions of six genes (Mn-sod, cas9, bax, cc-chem, ERα, and crh) associated with oxidative stress, cellular apoptosis, immune system, and endocrine system were prominently altered in the mixture exposure compared with the corresponding single treatment group of ZEN or FB1. Taken together, the regulatory standards of mycotoxins in food and feed should be updated based on the mixture effects of mycotoxins, and there is an increased need on effective detoxification methods for controlling and reducing the toxicity of multiple mycotoxins in animal feed and throughout the food supply chain.

Study of locomotion response and development in zebrafish (Danio rerio) embryos and larvae exposed to enniatin A, enniatin B, and beauvericin

Mycotoxins are secondary metabolites produced by a variety of fungi that contaminate food and feed resources, and are capable of inducing a wide range of toxicity. Here, we studied the developmental and behavioral toxicity in zebrafish (Danio rerio) embryos and larvae exposed to three mycotoxins: beauvericin (BEA), Enniatin A (ENN A), and Ennitain B (ENN B). Zebrafish embryos were collected after fertilization, treated individually from 1 to 6 dpf with BEA at 8, 16, 32 and, 64 μM and for both enniatins at 3.12, 6.25, 12.5 and, 25 μM. Mixture of mycotoxins were assayed as follows: i) for BEA + ENN A and BEA + ENN B at [32 + 12.5] μM and [16 + 6.25] μM; ii) for ENN A + ENN B at [12.5 + 12.5] μM and [6.25 + 6.25] μM and, iii) for BEA + ENN A + ENN B at [32 + 12.5 + 12.5] μM and [16 + 6.25 + 6.25] μM. Response was collected after a white light-flash intermittent coming on for 5 s during 2 h with a imaging platform. Outcomes measured were: time to death, response to light, and circadian rhythm. This last outcome was measured in a plate where embryos had evolved in natural intervals of light and dark until day 7 or in a plate maintained in darkness. Images of all stages and evolution were collected. Results indicated that mycotoxins induced toxicity at the concentrations tested. All exposed zebrafish induced developmental defects, specifically hatching time and motion activity. After exposure, fish showed enhanced baseline activity but they lost their responsiveness to light.

The Occurrence of Mycotoxins in Raw Materials and Fish Feeds in Europe and the Potential Effects of Deoxynivalenol (DON) on the Health and Growth of Farmed Fish Species-A Review

The first part of this study evaluates the occurrence of mycotoxin patterns in feedstuffs and fish feeds. Results were extrapolated from a large data pool derived from wheat (n = 857), corn (n = 725), soybean meal (n = 139) and fish feed (n = 44) samples in European countries and based on sample analyses by liquid chromatography/tandem mass spectrometry (LC-MS/MS) in the period between 2012-2019. Deoxynivalenol (DON) was readily present in corn (in 47% of the samples) > wheat (41%) > soybean meal (11%), and in aquafeeds (48%). Co-occurrence of mycotoxins was frequently observed in feedstuffs and aquafeed samples. For example, in corn, multi-mycotoxin occurrence was investigated by Spearman's correlations and odd ratios, and both showed co-occurrence of DON with its acetylated forms (3-AcDON, 15-AcDON) as well as with zearalenone (ZEN). The second part of this study summarizes the existing knowledge on the effects of DON on farmed fish species and evaluates the risk of DON exposure in fish, based on data from in vivo studies. A meta-analytical approach aimed to estimate to which extent DON affects feed intake and growth performance in fish. Corn was identified as the ingredient with the highest risk of contamination with DON and its acetylated forms, which often cannot be detected by commonly used rapid detection methods in feed mills. Periodical state-of-the-art mycotoxin analyses are essential to detect the full spectrum of mycotoxins in fish feeds aimed to prevent detrimental effects on farmed fish and subsequent economic losses for fish farmers. Because levels below the stated regulatory limits can reduce feed intake and growth performance, our results show that the risk of DON contamination is underestimated in the aquaculture industry.

Study of enzymatic activity in human neuroblastoma cells SH-SY5Y exposed to zearalenone's derivates and beauvericin

Beauvericin (BEA), α-zearalenol (α-ZEL) and β-zearalenol (β-ZEL), are produced by several Fusarium species that contaminate cereal grains. These mycotoxins can cause cytotoxicity and neurotoxicity in various cell lines and they are also capable of produce oxidative stress at molecular level. However, mammalian cells are equipped with a protective endogenous antioxidant system formed by no-enzymatic antioxidant and enzymatic protective systems such as glutathione peroxidase (GPx), glutathione S-transferase (GST), catalase (CAT) and superoxide dismutase (SOD). The aim of this study was evaluating the effects of α-ZEL, β-ZEL and BEA, on enzymatic GPx, GST, CAT and SOD activity in human neuroblastoma cells using the SH-SY5Y cell line, over 24 h and 48 h with different treatments at the following concentration range: from 1.56 to 12.5 μM for α-ZEL and β-ZEL, from 0.39 to 2.5 μM for BEA, from 1.87 to 25 μM for binary combinations and from 3.43 to 27.5 μM for tertiary combination. SH-SY5Y cells exposed to α-ZEL, β-ZEL and BEA revealed an overall increase in the activity of i) GPx, after 24 h of exposure up to 24-fold in individual treatments and 15-fold in binary combination; ii) GST after 24 h of exposure up to 10-fold (only in combination forms), and iii) SOD up to 3.5- and 5-fold in individual and combined treatment, respectively after 48 h of exposure. On the other hand, CAT activity decreased significantly in all treatments up to 92% after 24 h except for β-ZEL + BEA, which revealed the opposite.

Evaluation of the Multimycotoxin-Degrading Efficiency of Rhodococcus erythropolis NI1 Strain with the Three-Step Zebrafish Microinjection Method

The multimycotoxin-degrading efficiency of the Rhodococcus erythropolis NI1 strain was investigated with a previously developed three-step method. NI1 bacterial metabolites, single and combined mycotoxins and their NI1 degradation products, were injected into one cell stage zebrafish embryos in the same doses. Toxic and interaction effects were supplemented with UHPLC-MS/MS measurement of toxin concentrations. Results showed that the NI1 strain was able to degrade mycotoxins and their mixtures in different proportions, where a higher ratio of mycotoxins were reduced in combination than single ones. The NI1 strain reduced the toxic effects of mycotoxins and mixtures, except for the AFB1+T-2 mixture. Degradation products of the AFB1+T-2 mixture by the NI1 strain were more toxic than the initial AFB1+T-2 mixture, while the analytical results showed very high degradation, which means that the NI1 strain degraded this mixture to toxic degradation products. The NI1 strain was able to detoxify the AFB1, ZEN, T-2 toxins and mixtures (except for AFB1+T-2 mixture) during the degradation experiments, which means that the NI1 strain degraded these to non-toxic degradation products. The results demonstrate that single exposures of mycotoxins were very toxic. The combined exposure of mycotoxins had synergistic effects, except for ZEN+T-2 and AFB1+ZEN +T-2, whose mixtures had very strong antagonistic effects.

In silico methods for metabolomic and toxicity prediction of zearalenone, α-zearalenone and β-zearalenone

Zearalenone (ZEA), α-zearalenol (α-ZEL) and β-zearalenol (β-ZEL) (ZEA's metabolites) are co/present in cereals, fruits or their products. All three with other compounds, constitute a cocktail-mixture that consumers (and also animals) are exposed and never entirely evaluated, nor in vitro nor in vivo. Effect of ZEA has been correlated to endocrine disruptor alterations as well as its metabolites (α-ZEL and β-ZEL); however, toxic effects associated to metabolites generated once ingested are unknown and difficult to study. The present study defines the metabolomics profile of all three mycotoxins (ZEA, α-ZEL and β-ZEL) and explores the prediction of their toxic effects proposing an in silico workflow by using three programs of predictions: MetaTox, SwissADME and PASS online. Metabolomic profile was also defined and toxic effect evaluated for all metabolite products from Phase I and II reaction (a total of 15 compounds). Results revealed that products describing metabolomics profile were: from O-glucuronidation (1z and 2z for ZEA and 1 ab, 2 ab and 3 ab for ZEA's metabolites), S-sulfation (3z and 4z for ZEA and 4 ab, 5 ab and 6 ab for ZEA's metabolites) and hydrolysis (5z and 7 ab for ZEA's metabolites, respectively). Lipinsky's rule-of-five was followed by all compounds except those coming from O-glucuronidation (HBA>10). Metabolite products had better properties to reach blood brain barrier than initial mycotoxins. According to Pa values (probability of activation) order of toxic effects studied was carcinogenicity > nephrotoxic > hepatotoxic > endocrine disruptor > mutagenic (AMES TEST) > genotoxic. Prediction of inhibition, induction and substrate function on different isoforms of Cytochrome P450 (CYP1A1, CYP1A2, CYP2C9 and CYP3A4) varied for each compounds analyzed; similarly, for activation of caspases 3 and 8. Relying to our findings, the metabolomics profile of ZEA, α-ZEL and β-ZEL analyzed by in silico programs predicts alteration of systems/pathways/mechanisms that ends up causing several toxic effects, giving an excellent sight and direct studies before starting in vitro or in vivo assays contributing to 3Rs principle; however, confirmation can be only demonstrated by performing those assays.

Reducing the effect of beauvericin on neuroblastoma SH-SY5Y cell line by natural products

In the present work, different natural compounds from coffee by-product extracts (coffee silverskin and spent coffee) rich in polyphenols, was investigated against beauvericin (BEA) induced-cytotoxicity on SH-SY5Y cells. Spent coffee arise as waste products through the production of instant coffee and coffee brewing; while the silverskin is a tegument which is removed and eliminated with toasting coffee grains. First of all, polyphenol extraction methods, measurement of total polyphenols content and its identification were carried out. Afterwards evaluating in vitro effects with MTT assay on SH-SY5Y cells of coffee by-product extracts and mycotoxins at different concentrations and exposure times was performed. TPC in silverskin coffee by-product extracts was >10 times higher than in spent coffee by-product extracts. Chlorogenic acid was the majority polyphenol detected. Viability for BEA reached IC₅₀ values at 72h (2.5 μM); boiling water silverskin coffee extract reached the highest viability also in pre-treatment BEA exposure and compared with MeOH and MeOH:H₂O (v/v, 50:50) extracts. These results in SH-SY5Y cells highlight the use of such residues as supplements or bioactive compounds in the future.