Evaluation of 2,4-dichlorophenol exposure of Japanese medaka, Oryzias latipes, using a metabolomics approach

Unveiling behaviors of 8:2 fluorotelomer sulfonic acid (8:2 FTSA) in Arabidopsis thaliana: Bioaccumulation, biotransformation and molecular mechanisms of phytotoxicity

8:2 fluorotelomer sulfonic acid (8:2 FTSA) has been commonly detected in the environment, but its behaviors in plants are not sufficiently known. Here, the regular and multi-omics analyses were used to comprehensively investigate the bioaccumulation, biotransformation, and toxicity of 8:2 FTSA in Arabidopsis thaliana. Our results demonstrated that 8:2 FTSA was taken up by A. thaliana roots and translocated to leaves, stems, flowers, and seeds. 8:2 FTSA could be successfully biotransformed to several intermediates and stable perfluorocarboxylic acids (PFCAs) catalyzed by plant enzymes. The plant revealed significant growth inhibition and oxidative damage under 8:2 FTSA exposure. Metabolomics analysis showed that 8:2 FTSA affected the porphyrin and secondary metabolisms, resulting in the promotion of plant photosynthesis and antioxidant capacity. Transcriptomic analysis indicated that differentially expressed genes (DEGs) were related to transformation and transport processes. Integrative transcriptomic and metabolomic analysis revealed that DEGs and differentially expressed metabolites (DEMs) in plants were predominantly enriched in the carbohydrate metabolism, amino acid metabolism, and lipid metabolism pathways, resulting in greater energy consumption, generation of more nonenzymatic antioxidants, alteration of the cellular membrane composition, and inhibition of plant development. This study provides the first insights into the molecular mechanisms of 8:2 FTSA stress response in plants.

Single and mixture toxicity of cadmium and copper to swim bladder in early life stages of Japanese medaka (Oryzias latipes)

Toxicity observed in aquatic ecosystems often cannot be explained by the action of a single pollutant. Likewise, evaluation standards formulated by a single effect cannot truly reflect the environmental quality requirements. The study of mixtures is needed to provide environmental relevance and knowledge of combined toxicity. In this study, the embryos of Japanese medaka (Oryzias latipes) were treated with individual and binary mixture of copper (Cu) and cadmium (Cd) until 12 days post-fertilization (dpf). Hatching, mortality, development, histology and gene expression were assessed. Our results showed that the highest concentration mixture of Cd (10 mg/L) and Cu (1 mg/L) affected survival, hatching time and hatching success. Occurrence of uninflated swim bladder was the highest (value) with exposure to 10 mg/L Cd. Swim bladder was commonly over-inflated in a mixture (0.1 mg/L Cd + 1.0 mg/L Cu) exposure. Individuals exposed to the mixture (0.1 Cd + 1.0 Cu mg/L) showed up to a 7.69% increase in swim bladder area compared to the control group. The mixtures containing 0.1 or 10 mg/L Cd, each with 1.0 mg/L Cu resulted in significantly increased of Pbx1b expression, higher than any Cd or Cu alone (p < 0.01). In the co-exposure group (0.1/10 Cd + 1.0 Cu mg/L), Pbx1b expression was found at 12 dpf but not 7 dpf in controls. Higher concentrations of Cd may progressively reduce Pbx1b expression, potentially explaining why 75% of individuals in the 10 mg/L Cd group failed to inflate their swim bladders. Additionally, the swim bladder proved to be a valuable bio-indicator for biological evaluation.

2,4-dichlorophenol exposure induces lipid accumulation and reactive oxygen species formation in zebrafish embryos

2,4-dichlorophenol (2,4-DCP) is commonly found in the aquatic environment that can be formed by the conversion of triclosan, which is a high production volume endocrine disturbing chemical. The study aims to understand the potential developmental toxicity of 2,4-DCP by using the in vivo zebrafish. We exposed the 2,4-DCP to the zebrafish embryos and collected the samples at several selected developmental stages (70-85% epiboly/10-12 somite/prim-5) for the whole mount in situ hybridization. The staining is used to investigate the ventral patterning, presumptive neural formation, and brain development. Results suggested that the 2,4-DCP exposure (up to 2.5 mg/L) did not affect the tested developmental processes in the survived embryos. Further experiments on lipid accumulation and oxidative stress were carried out at 5 days post fertilization larvae. Results showed the accumulation of oil droplets and induction of reactive oxygen species (ROS) in the larvae after the highest dosage exposure (2.5 mg/L). The real-time qPCR results suggested that the alternation of lipid metabolism was due to the reduced mRNA expressions of proliferator-activated receptor alpha (ppar-α) and acetyl-CoA carboxylase (acc); while the suppressed glutathione peroxidase (gpx) mRNA expression was responsible for the induction of the ROS. To conclude, the study provided scientific merits of understanding 2,4-DCP toxicity, and suggested the possible underlying mechanism of the defects.

Multi-omic approach to evaluate the response of gilt-head sea bream (Sparus aurata) exposed to the UV filter sulisobenzone

Sulisobenzone (BP-4) is one of the benzophenone type UV filters most frequently detected in aquatic ecosystems. As a suspected endocrine disrupting compound, scarce information is available yet about other molecular effects and its mechanism of action. Here, we used an integrated transcriptomic and metabolomic approach to improve the current understanding on the toxicity of BP-4 towards aquatic species. Gilt-head sea bream individuals were exposed at environmentally relevant concentrations (10 μg L^-1) for 22 days. Transcriptomic analysis revealed 371 differentially expressed genes in liver while metabolomic analysis identified 123 differentially modulated features in plasma and 118 in liver. Integration of transcriptomic and metabolomic data showed disruption of the energy metabolism (>10 pathways related to the metabolism of amino acids and carbohydrates were impacted) and lipid metabolism (5 glycerophospholipids and the expression of 3 enzymes were affected), suggesting oxidative stress. We also observed, for the first time in vivo and at environmental relevant concentrations, the disruption of several enzymes involved in the steroid and thyroid hormones biosynthesis. DNA and RNA synthesis was also impacted by changes in the purine and pyrimidine metabolisms. Overall, the multiomic workflow presented here increases the evidence on suspected effects of BP-4 exposure and identifies additional modes of action of the compounds that could have been overlooked by using single omic approaches.

Ecological and toxicological assessments of anthropogenic contaminants based on environmental metabolomics

There has long been a great concern with growing anthropogenic contaminants and their ecological and toxicological effects on living organisms and the surrounding environment for decades. Metabolomics, a functional readout of cellular activity, can capture organismal responses to various contaminant-related stressors, acquiring direct signatures to illustrate the environmental behaviours of anthropogenic contaminants better. This review entails the application of metabolomics to profile metabolic responses of environmental organisms, e.g. animals (rodents, fish, crustacean and earthworms) and microorganisms (bacteria, yeast and microalgae) to different anthropogenic contaminants, including heavy metals, nanomaterials, pesticides, pharmaceutical and personal products, persistent organic pollutants, and assesses their ecotoxicological impacts with regard to literature published in the recent five years. Contaminant-induced metabolism alteration and up/down-regulation of metabolic pathways are revealed in typical organisms. The obtained insights of variations in global metabolism provide a distinct understanding of how anthropogenic contaminants exert influences on specific metabolic pathways on living organisms. Thus with a novel ecotechnique of environmental metabolomics, risk assessments of anthropogenic contaminants are profoundly demonstrated.

Photodegradation of 2,4-dichlorophenol by supported Pd(X2) catalyst (X = Cl, Br, N3): a HOMO manipulating point of view

Three different palladium(II) complexes with ligands containing nitrogenized aromatic rings were investigated theoretically as model to obtain the computational band gap energies. The results demonstrated promising possibility for designing palladium(II) complexes with photocatalytic properties at visible light irradiation. Deliberated products were synthesized via grafting on the silica-coated Fe₃O₄ magnetic nanoparticles (Fe₃O₄@SiO₂). Formation of complexes on the surface of Fe₃O₄@SiO₂, as insoluble and reusable photocatalysts, was proved by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric (TGA), X-ray photoelectron spectroscopy (XPS), vibrating sample magnetometer (VSM), transmission electron microscope (TEM), and scanning electron microscopy (SEM) analyses. The trend of the band gap energies of prepared structures was calculated via experimental and theoretical methods. The photocatalytic capability of these nanoparticles was investigated in degradation of 2,4-dichlorophenol by means of HPLC analysis. A tentative reaction mechanism for the formation of intermediates was proposed. Graphical abstract ᅟ.

Baseline levels of metabolites in different tissues of mussel Mytilus galloprovincialis (Bivalvia: Mytilidae)

The Mediterranean mussel Mytilus galloprovincialis (Lamarck 1819) is a popular shellfish commonly included in human diet and is routinely used as bioindicator in environmental monitoring programmes worldwide. Recently, metabolomics has emerged as a powerful tool both in food research and ecotoxicology for monitoring mussels' freshness and assessing the effects of environmental changes. However, there is still a paucity of data on complete metabolic baseline of mussel tissues. To mitigate this knowledge gap, similarities and differences in metabolite profile of digestive gland (DG), gills (G), and posterior adductor muscle (PAM) of aquaculture-farmed M. galloprovincialis were herein investigated by a proton nuclear magnetic resonance (¹H NMR)-based metabolomic approach and discussed considering their physiological role. A total of 44 metabolites were identified in mussel tissues and grouped in amino acids, energy metabolites, osmolytes, neurotransmitters, nucleotides, alkaloids, and miscellaneous metabolites. A PCA showed that mussel tissues clustered separately from each other, suggesting a clear differentiation in their metabolic profiles. A Venn diagram revealed that mussel DG, G and PAM shared 27 (61.36%) common metabolites, though with different concentrations. Osmolytes were found to dominate the metabolome of all tissues. The DG exhibited higher level of glutathione and carbohydrates. The G showed greater level of osmolytes and the exclusive presence of neurotransmitters, namely acetylcholine and serotonin. In PAM higher levels of energetics-related metabolites were found. Overall, findings from this study are helpful for a better understanding of mussel tissue-specific physiological functions as well as for future NMR-based metabolomic investigations of marine mussel health and safety.

Gas Chromatography-Mass Spectrometry for Metabolite Profiling of Japanese Black Cattle Naturally Contaminated with Zearalenone and Sterigmatocystin

The objective of this study was to evaluate the metabolic profile of cattle fed with or without zearalenone (ZEN) and sterigmatocystin (STC)-contaminated diets using a gas chromatography-mass spectrometry metabolomics approach. Urinary samples were collected from individual animals (n = 6 per herd) from fattening female Japanese Black (JB) cattle herds (23 months old, 550–600 kg). Herd 1 had persistently high urinary ZEN and STC concentrations due to the presence of contaminated rice straw. Herd 2, the second female JB fattening herd (23 months old, 550–600 kg), received the same dietary feed as Herd 1, with non-contaminated rice straw. Urine samples were collected from Herd 1, two weeks after the contaminated rice straw was replaced with uncontaminated rice straw (Herd 1N). Identified metabolites were subjected to principal component analysis (PCA) and ANOVA. The PCA revealed that the effects on cattle metabolites depended on ZEN and STC concentrations. The contamination of cattle feed with multiple mycotoxins may alter systemic metabolic processes, including metabolites associated with ATP generation, amino acids, glycine-conjugates, organic acids, and purine bases. The results obtained from Herd 1N indicate that a two-week remedy period was not sufficient to improve the levels of urinary metabolites, suggesting that chronic contamination with mycotoxins may have long-term harmful effects on the systemic metabolism of cattle.

Untargeted metabolomics approach for unraveling robust biomarkers of nutritional status in fasted gilthead sea bream (Sparus aurata)

A metabolomic study has been performed to identify sensitive and robust biomarkers of malnutrition in farmed fish, using gilthead sea bream (Sparus aurata) as a model. The metabolomic fingerprinting of serum from fasted fish was assessed by means of ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. More than 15,000 different m/z ions were detected and Partial Least Squares–Discriminant analysis allowed a clear differentiation between the two experimental groups (fed and 10-day fasted fish) with more than 90% of total variance explained by the two first components. The most significant metabolites (up to 45) were elucidated on the basis of their tandem mass spectra with a broad representation of amino acids, oligopeptides, urea cycle metabolites, L-carnitine-related metabolites, glutathione-related metabolites, fatty acids, lysophosphatidic acids, phosphatidylcholines as well as biotin- and noradrenaline-related metabolites. This untargeted approach highlighted important adaptive responses in energy and oxidative metabolism, contributing to identify robust and nutritionally-regulated biomarkers of health and metabolic condition that will serve to assess the welfare status of farmed fish.