Per- and polyfluoroalkyl substances (PFASs) have been found to be widely present in soil. Dissolved organic matter (DOM) in soil are supposed to greatly affect the bioavailability of PFASs in soil. Herein, hydroponic experiments were conducted to understand the impacts of two kinds of typical DOM, bovine serum albumin (BSA) and humic acid (HA), on the uptake and translocation of legacy PFASs and their emerging alternatives, perfluorooctane sulfonic acid (PFOS), perfluorooctane acid (PFOA), perfluorohexane sulfonic (PFHxS) and 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFESA) in wheat (Triticum aestivum L.). The results indicated that both HA and BSA significantly inhibited the bioaccumulation and translocation of PFASs in the roots and shoots of wheat, and the impacts of BSA were greater than HA. This difference was explained by the greater binding affinities of the four PFASs with BSA than with HA, as evidenced by the equilibrium dialysis and isothermal titration calorimetry (ITC) analyses. It was noting that inhibition impacts of the BSA-HA mixture (1:1) were lower than BSA alone. The results of Fourier transform infrared (FT-IR) spectroscopy and excitation-emission matrix (EEM) fluorescence spectroscopy suggested that HA could bind with the fluorescent tryptophan residues in BSA greatly, competing the binding sites with PFASs and forming a cover on the surface of BSA. As a result, the binding of PFASs with BSA-HA complex was much lower than that with BSA, but close to HA. The results of this study shed light on the impacts of DOM in soil on the bioaccumulation and translocation of PFASs in plants.

Effluent is often treated with ozone before being discharged into a natural water environment. This process will change the interaction between effluent organic matter and pollutants in aquatic environment. The impact of ozonation on complexation between dissolved organic matter in such wastewater and sulfadimidine often found in natural water was studied in laboratory experiments using four types of real wastewater. Ozonation was found to decrease the proportion of organic matter with a molecular weight greater than 5 kDa as well as protein-like, fulvic-like and humic-like components, but except the proportion of hydrophilic components. The aromaticity of the dissolved organic matter was also reduced after ozonation. The complexation of tryptophan and tyrosine with sulfadimidine mainly depends on their hydrophobicity and large molecular weight. Ozonation of fulvic and humic acid tends to produce small and medium molecular weight hydrophilics. The complexation of humic and fulvic acids with sulfadimidine was enhanced by ozonation. Dissolved organic matter, with or without oxidation, were found to weaken sulfadimidine’s inhibition of microbial growth, especially for Aeromonas and Acinetobacter species. This finding will expand our understanding about the impact of advanced treatment processes on the dissolved organic matters’ properties in effluent.

Known as a cause of food poisoning, Bacillus cereus (B. cereus) is widespread in nature. Cereulide, the heat-stable and acid-resistant emetic toxin which is produced by some B. cereus strains, is often associated with foodborne outbreaks, and causes acute emetic toxicity at high dosage exposure. However, the toxicological effect and underlying mechanism caused by chronic low-dose cereulide exposure require to be further addressed. In the study, based on mouse model, cereulide exposure (50 μg/kg body weight) for 28 days induced intestinal inflammation, gut microbiota dysbiosis and food intake reduction. According to the cell models, low dose cereulide exposure disrupted the intestinal barrier function and caused intestinal inflammation, which were resulted from endoplasmic reticulum (ER) stress IRE1/XBP1/CHOP pathway activation to induce cell apoptosis and inflammatory cytokines production. For gut microbiota, cereulide decreased the abundances of Lactobacillus and Oscillospira. Furthermore, cereulide disordered the metabolisms of gut microbiota, which exhibited the inhibitions of butyrate and tryptophan. Interestingly, cereulide exposure also inhibited the tryptophan hydroxylase to produce the serotonin in the gut and brain, which might lead to depression-like food intake reduction. Butyrate supplementation (100 mg/kg body weight) significantly reduced intestinal inflammation and serotonin biosynthesis suppression caused by cereulide in mice. In conclusion, chronic cereulide exposure induced ER stress to cause intestinal inflammation, gut microbiota dysbiosis and serotonin biosynthesis suppression. IRE1 could be the therapeutic target and butyrate supplementation is the potential prevention strategy.

Hydrogen peroxide (H₂O₂), as a common disinfectant, has been extensively used in aquaculture. The toxicity of high ambient H₂O₂ for gills and liver of fish has received attention from many researchers. However, whether H₂O₂ exposure induced brain injury and neurotoxicity has not been reported in fish. Therefore, this study aimed to explore the potential mechanism of H₂O₂ toxicity in brain of common carp via transcriptome analysis and biochemical parameter detection. The fish were exposed to 0 (control) and 1 mM of H₂O₂ for 1 h per day lasting 14 days. The results showed that H₂O₂ exposure caused oxidative damage in brain evidenced by decreased glutathione (GSH), total antioxidant capacity (T-AOC) and nicotinamide adenine dinucleotide (NAD⁺) levels, and increased formation of malondialdehyde (MDA) and 8-hydroxy-2′-deoxyguanosine (8-OHdG). Meanwhile, H₂O₂ exposure reduced 5-hydroxytryptamine (5-HT) level, and down-regulated tryptophan hydroxylase 1 (tph1a), tph2, 5-hydroxytryptamine receptor 1A-beta (htr1ab) and htr2b expression in brain. Transcriptome analysis showed that H₂O₂ exposure up-regulated 604 genes and down-regulated 1209 genes in brain. Go enrichment displayed that the differently expressed genes (DEGs) were enriched mainly in cellular process, single-organism process, metabolic process, and biological regulation in the biological process category. Further, KEGG enrichment indicated that H₂O₂ exposure led to dysregulation of neurotransmitter signals including depression of glutamatergic synapse, GABAergic synapse and endocannabinoid signaling. Also, we found the alteration of three key pathways including calcium, cAMP and HIF-1 in brain after H₂O₂ exposure. In conclusion, our data indicated that H₂O₂ exposure induced oxidative damage and neurotoxicity, possibly related to dysregulation of neurotransmitters and calcium, cAMP and HIF-1 signaling pathways, which may adversely affect learning, memory and social responses of common carp. This study provided novel insight into biological effects and underlying mechanism of H₂O₂ toxicity in aquatic animal, and contributed to proper application of H₂O₂ in aquaculture.

The present study was performed to evaluate the neurobehavioural deficit induced by nonylphenol (NP), a well-known xenobiotic chemical. The neurotoxic mechanism from oxidative stress and serotonin-related progress was also investigated. Caenorhabditis elegans was exposed at different levels of NP ranging from 0 to 200 μg L⁻¹ for 10 days. The results revealed that from a relatively low concentration (i.e., 10 μg L⁻¹), significant effects including decreased head thrashes, body bends and forging behaviour could be observed, along with impaired learning and memory behaviour plasticity. The level of reactive oxygen species (ROS) in head was significantly elevated with the increase of NP concentrations from 10 to 200 μg L⁻¹. Through antioxidant experiment, the oxidative damage caused by NP restored to some extent. At a NP concentration of 200 μg L⁻¹, the significant increased expression of stress-related genes, including sod-1, sod-3, ctl-2, ctl-3 and cyp-35A2 gene, was observed from integrated gene expression profiles. In addition, in comparison with wild-type N2 worms, the ROS accumulation was increased significantly with the mutation of sod-3. Tryptophan hydroxylase (TPH) in ADF and NSM neurons sharply decreased at the concentrations of 10–200 μg L⁻¹. The transcription of TPH synthesis-related genes and serotonin-related genes were both suppressed, including tph-1, cat-1, cat-4, ser-1, and mod-5. Overall, these results indicated that NP could induce neurotoxicity on Caenorhabditis elegans through excessive induction of ROS and disturbance synthesis of serotonin. The conducted research opened up new avenues for more effective exploration of neurotoxicity caused by NP.

Epidemiological studies indicate that exposure to persistent organic pollutants is positively associated with the prevalence of obesity. To delineate the potential role of technical-grade chlordane in obesity development, chlordane metabolism and chlordane-induced metabolic changes were investigated in mice fed high-fat diet (HFD) over a 6-week period. Gas chromatography–electron capture detector analysis showed that HFD induced more accumulation of technical chlordane in the liver, muscle and adipose tissue. The enantioselectivities of oxychlordane in selected tissues were also influenced by HFD. 1H NMR-based liver metabolome indicated that technical chlordane can enhance the metabolic alterations induced by HFD. Compared with the low-fat diet (LFD) group, no differences were observed in the LFD + chlordane group. However, as many as 16 metabolites were significantly different between the HFD group and HFD + chlordane group. Moreover, compared to the LFD + chlordane group, the abundances of 24 metabolites significantly increased or decreased in the HFD + chlordane group. Twenty metabolites were altered in the HFD group compared to the LFD group. Tryptophan profiling suggested that both chlordane and HFD can disturb tryptophan catabolism. These interactions between technical chlordane and HFD suggest that technical chlordane is a candidate obesogen.

Bacterially extracellular biofilms play a critical role in relieving toxicity of fluoroquinolone antibiotic (FQA) pollutants, yet it is unclear whether antibiotic attack may be defused by a bacterial one-two punch strategy associated with metal-reinforced detoxification efficiency. Our findings help to assign functions to specific structural features of biofilms, as they strongly imply a molecularly regulated mechanism by which freely accessed alkali–earth metals in natural waters affect the cellular uptake of FQAs at the water-biofilm interface. Specifically, formation of alkali-earth-metal (Ca²⁺ or Mg²⁺) bridge between modeling ciprofloxacin and biofilms of Escherichia coli regulates the trans-biofilm transport rate of FQAs towards cells (135-nm-thick biofilm). As the addition of Ca²⁺ and Mg²⁺ (0–3.5 mmol/L, CIP: 1.25 μmol/L), the transport rates were reduced to 52.4% and 63.0%, respectively. Computational chemistry analysis further demonstrated a deprotonated carboxyl in the tryptophan residues of biofilms acted as a major bridge site, of which one side is a metal and the other is a metal girder jointly connected to the carboxyl and carbonyl of a FQA. The bacterial growth rate depends on the bridging energy at anchoring site, which underlines the environmental importance of metal bridge formed in biofilm matrices in bacterially antibiotic resistance.

Dechlorane 602 (Dec 602), a chlorinated flame retardant, has been widely detected in different environmental matrices and biota. However, toxicity data for Dec 602 seldom have been reported. A metabolomics study based on ultra-high performance liquid chromatography coupled with ion trap time-of-flight mass spectrometry was employed to study the urine and sera metabolic profiles of mice administered with Dec 602 (0, 0.001, 0.1, and 10 mg/kg body weight per day) for 7 days. A significant difference in metabolic profiling was observed between the Dec 602 treated group and the control group by multivariate analysis, which directly reflected the metabolic perturbations caused by Dec 602. The metabolomics analyses of urine from Dec 602-exposed animals exhibited an increase in the levels of thymidine and tryptophan as well as a decrease in the levels of tyrosine, 12,13-dihydroxy-9Z-octadecenoic acid, 2-hydroxyhexadecanoic acid and cuminaldehyde. The metabolomics analyses of sera showed a decrease in the levels of kynurenic acid, daidzein, adenosine, xanthurenic acid and hypoxanthine from Dec 602-exposed animals. These findings indicated Dec 602 induced disturbance in phenylalanine, tyrosine and tryptophan biosynthesis, tryptophan metabolism, tyrosine metabolism, pyrimidine metabolism, purine metabolism, ubiquinone and other terpenoid-quinone biosynthesis; phenylalanine metabolism and aminoacyl-tRNA biosynthesis. Significant alterations of immune and neurotransmitter-related metabolites (tyrosine, tryptophan, kynurenic acid, and xanthurenic acid) suggest that the toxic effects of Dec 602 may contribute to its interactions with the immune and neuronal systems. This study demonstrated that the UHPLC-ESI-IT-TOF-MS-based metabolomic approach can obtain more specific insights into the potential toxic effects of Dec 602 at molecular level.

At present, the majority of investigations concerning nanotoxicology in the nematode C. elegans address short-term effects. While this approach allows for the identification of uptake pathways, exposition and acute toxicity, nanoparticle-organism interactions that manifest later in the adult life of C. elegans are missed. Here we show that a microhabitat composed of liquid S-medium and live bacteria in microtiter wells prolongs C. elegans longevity and is optimally suited to monitor chronic eNP-effects over the entire life span (about 34 days) of the nematode. Silver (Ag) nanoparticles reduced C. elegans life span in concentrations ≥10 μg/mL, whereas nano ZnO and CeO₂ (1–160 μg/mL) had no effect on longevity. Monitoring of locomotion behaviors throughout the entire life span of C. elegans showed that Ag NPs accelerate the age-associated decline of swimming and increase of uncoordinated movements at concentrations of ≥10 μg/mL, whereas neuromuscular defects did not occur in response to ZnO and CeO₂ NPs. By means of a fluorescing reporter worm expressing tryptophan hydroxylase-1::DsRed Ag NP-induced behavioral defects were correlated to axonal protein aggregation and neurodegeneration in single serotonergic HSN as well as sensory ADF neurons. Notably, serotonergic ADF neurons represented a sensitive target for Ag NPs in comparison to GABAergic neurons that showed no signs of degeneration under the same conditions. We conclude that due to its analogy to the jellylike boom culture of C. elegans on microbe-rich rotting plant material liquid S-medium culture in spatially confined microtiter wells represents a relevant as well as practical tool for comparative identification of age-resolved nanoparticle effects and vulnerabilities in a significant target organism. Consistent with this, specifically middle-aged nematodes showed premature neuromuscular defects after Ag NP-exposure.

Decabromodiphenyl ether (BDE-209), as a major component of brominated flame retardants, has been detected in the agricultural soil in considerable amount. Given that BDE-209 is toxic, ubiquitous and persistent, BDE-209 might induce toxic effects on rice cultivars planted in contaminated soil. A comparative study was conducted on phytotoxicities and GC-MS based antioxidant-related metabolite levels to investigate the differences of phytotoxicities of BDE-209 to rice cultivars in Yangtze River Delta of China. Rice seedlings were treated with BDE-209 at 0, 10, 50, 100 and 500 μg/L in a hydroponic setup. Results showed that BDE-209-induced phytotoxicites were cultivar-dependent and that the antioxidant defense systems in the cultivars were disturbed differently. Among the three selected cultivars (Jiayou 5, Lianjing 7 and Yongyou 9), Jiayou 5 and Lianjing 7 displayed lower toxic effects than Yongyou 9 in terms of the growth inhibition, lipid peroxidation and DNA damage. The increases of antioxidant enzymes were significantly higher in Jiayou 5 and Lianjing 7 than those in Yongyou 9. Multivariate analysis of antioxidant-related metabolites in the three cultivars indicated that l-tryptophan and l-valine were the most important ones among 10 metabolites responsible for the separation of cultivars. The up-regulation of l-tryptophan and l-valine were likely plant strategies to increase their tolerance. The current results provided an insight into the development of rice cultivars with higher BDE-209 tolerance.