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Multidrug resistance proteins (MRPs), members of the ATP-binding cassette transporter (ABC transporter) family, are pivotal for transporting endo- and xenobiotics, which confer resistance to anticancer agents and contribute to the clearance of oxidative products. However, their function in many biological processes is still unclear. We investigated the role of an evolutionarily conserved MRP in metabolic homeostasis by knocking down the expression of Drosophila multidrug-resistance like protein 1 (MRP) in several tissues involved in regulating metabolism, including the gut, fat body, and Malpighian tubules. Interestingly, only suppression of MRP in the Malpighian tubules, the functional equivalent to the human kidney, was sufficient to cause abnormal lipid accumulation and disrupt feeding behavior. Furthermore, reduced Malpighian tubule MRP expression resulted in increased Hr96 (homolog of human pregnane X receptor) expression. Hr96 is known to play a role in detoxification and lipid metabolism processes. Reduced expression of MRP in the Malpighian tubules also conveyed resistance to oxidative stress, as well as reduced normal levels of reactive oxygen species in adult flies. This study reveals that an evolutionarily conserved MRP is required in Drosophila Malpighian tubules for proper metabolic homeostasis.

This paper reports on the comparative characteristics and properties of the metabolites derived from methyl red (MR) decolorization by Lysinibacillus fusiformis strain W1B6 under static and shaking conditions. A batch culture system was used to investigate the effect of aeration on azoreductase activity in the biodegradation process, transformation of colour removal and the metabolite products. Biodegradation analysis was monitored using Fourier transform infrared spectroscopy and high-performance liquid chromatography while metabolites were determined using gas chromatography–mass spectroscopy. Phytotoxicity and anti-microbial tests were also conducted to detect the toxicity of metabolites. The results showed that this strain grew more rapidly under shaking conditions while azoreductase activity increased more rapidly under static conditions. Despite that, no significant difference in the decolorization was observed under both static and shaking conditions with up to 96% and 93.6% decolorization achieved, respectively, within 4 h of incubation. MR was degraded into two fragmented compounds, i.e. 2-aminobenzoic acid and N,N-dimethyl-1.4-benzenediamine. The concentration of 2-amino benzoic acid was higher under static conditions resulting the biotransformation of 2-amino benzoic acid into methyl anthranilate more rapidly under static conditions. Other metabolites were also detected as intermediate biotransformation products and by-products. Less or no toxic effect was found in the metabolite degradation products under both culture conditions.

The gut microbiome is indispensable for the host physiological functioning. Yet, the impact of non-nutritious dietary compounds on the human gut microbiota and the role of the gut microbes in their metabolism and potential adverse biological effects have been overlooked. Identifying potential hazards and benefits would contribute to protecting and harnessing the gut microbiome's role in supporting human health. We discuss the evidence on the potential detrimental impact of certain food additives and microplastics on the gut microbiome and human health, with a focus on underlying mechanisms and causality. We provide recommendations for the incorporation of gut microbiome science in food risk assessment and identify the knowledge and tools needed to fill these gaps. The incorporation of gut microbiome endpoints to safety assessments, together with well-established toxicity and mutagenicity studies, might better inform the risk assessment of certain contaminants in food, and/or food additives.

Leather tanning technology impacts negatively on the environment as a result of chemicals in the tannery effluents that increases the concentrations of chemical oxygen demand, Biological oxygen demand, total dissolved solids, total Kjeldahl Nitrogen and formation of Cr(VI) among others in the environment. This has led to the profiling of the industry by legislative bodies as a major source of pollution and hence urgent cleaner and eco-friendly innovative technologies are required that will mitigate the environmental pollution. Many studies have recommended green chemistry tanning protocols and systems involving plants since are non-carcinogenic, non-toxic, biodegradable, agro-renewable, sustainable and economical. Numerous studies have evaluated the potential of phytochemistry in leather tanning processes. However, these studies only focused on individual processes or individual plant phytochemicals. Hence this review compiles the selected plants, their phytochemical screening results, their applications in tanning process and their potential for leather tanning. The review has shown enormous capacity of plants and their phytochemicals that can replace synthetic inorganic materials in leather processing and guarantee quality. Plants have a greater applicability in this industry since they have multiple beneficial actions during processing and the final processed leather. Some plants can be used at all tanning processes due to wide variety of important phytochemicals and the final leather is more superior quality to the conventionally processed leather. Other studies have alluded to the possibility of some plant products that have the potential in the industry but yet to be utilized. Further studies have been recommended. [ABSTRACT FROM AUTHOR]

In this work, the detection and quantification of p‐benzoquinone (BQ) was performed by differential pulse voltammetry (DPV) with a diamond film sensor. The calibration curve and the limits of detection and quantification for BQ were estimated. DPV was compared to high‐performance liquid chromatography (HPLC) analysis, leading to a satisfactory result in terms of stability and sensitive response. As a novel aim, a combined electrochemical method for environmental application has been developed to oxidize and detect BQ using diamond films. A set of galvanostatic electrochemical oxidation experiments with 130 mL of BQ solution were accomplished in order to understand the effect of current density, the concentration of the pollutant and the initial pH using different electrolytes with similar conductivity. The optimal operating conditions were achieved at 33.3 mA cm−2, 100 mg L−1 of BQ at pH 5.0 with 50 mM Na2SO4. Additionally, the evolution of short‐chain carboxylic acids of that test was followed over time in order to suggest a possible degradation route. The results were described and discussed in the light of the existing literature. [ABSTRACT FROM AUTHOR]

In yeasts, the plasma membrane forms the barrier that protects the cell from the outside world, but also gathers and keeps valuable compounds inside. Although it is often suggested that hydrophobic molecules surpass this checkpoint by simple diffusion, it now becomes evident that protein‐facilitated transport mechanisms allow for selective import and export of triglycerides, fatty acids, alkanes, and sterols in yeasts. During biomass production, hydrophobic carbon sources enter and exit the cell efficiently in a strictly regulated manner that helps avoid toxicity. Furthermore, various molecules, such as yeast pheromones, secondary metabolites and xenobiotics, are exported to ensure cell–cell communication, or increase chances of survival. This review summarizes the current knowledge on how hydrophobic compounds interact with protein‐facilitated transport systems on the plasma membrane and how selective import and export across the yeast plasma membrane is achieved. Both the model organism Saccharomyces cerevisiae, as well as unconventional yeasts are discussed. [ABSTRACT FROM AUTHOR]

Abstract The variations of haematological parameters hematocrit, hemoglobin concentration, leukocyte and erythrocyte count have been used as pollution and physiological indicators of organic dysfunction in both environmental and aquaculture studies. These parameters are commonly applied as prognostic and diagnostic tools in fish health status. However, there are both extrinsic and intrinsic factors to consider when performing a blood test, because a major limitation for field researchers is that the "rules" for animal or human haematology do not always apply to wildlife. The main objective of this review is to show how some environmental and xenobiotic factors are capable to modulating the haematic cells. Visualizing the strengths and limitations of a haematological analysis in the health assessment of wild and culture fish. Finally, we point out the importance of the use of mitochondrial activities as part of haematological evaluations associated to environment or aquaculture stress. Graphical abstract Unlabelled Image Highlights • Haematology can evaluate normal blood cells variation by intrinsic or extrinsic factors. • Fish blood cells alteration can be observed through eritrogram and leukogram. • Haematological parameters can be indicator of environmental quality. • Haematologic evaluation may assist the veterinary staff with detecting disease in fish. • Mitochondrial activity can be a good indicator of fish health state. • Mitochondria dysfunction may be associated with anemia development. [ABSTRACT FROM AUTHOR]

Gliclazide is a pharmaceutical product used in the treatment of type 2 diabetes. However, this drug is considered to be highly undesirable when present in the environment. We tested in vitro the biodegradation of gliclazide as the sole source of carbon and energy by a microbial consortium. After a 5-month adaptation period in batch culture, two bacterial strains were isolated and identified, namely, Aeromonas hydrophila and Serratia odorifera. With an initial concentration of gliclazide at 0.5 g/L, these two bacteria and their combined culture degraded gliclazide with a specific activity of 22.3, 24.1, and 19.2 ng/(mg·h) and a yield of 88.88%, 82.94%, and 95.88%, respectively. Experimental results reveal a removal efficiency of 98.904% at an inlet concentration of 5 g/L and a flow rate of 14 L/h. The maximum removal efficiency of the biotrickling filter was 99.6%, at a gliclazide inlet concentration of 0.5, 1, and 5 g/L and a flow rate of 6.3 L/h. Interestingly, it was observed that after a period of 12 months, the two dominant strains differed from those present in the initial inocula. Thus, the high elimination efficiencies obtained in this study reveal the interest of the use, for the first time, of a biotrickling filter for the study of the biodegradation of gliclazide. Obtaining a microbial consortium strongly adapted to this substrate may prove to be an interesting alternative for a possible application in the treatment, before discharge, of wastewater containing this molecule or other related molecules, especially in the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

Two volatile alkaloids, methyl (MMA) and isopropyl N -methylanthranilates (IMA), identified in the essential oil of Choisya ternata Kunth (Rutaceae), have been proven to possess polypharmacological properties (antinociceptive, anti-inflammatory, gastro-, hepato-, nephroprotective activities, anxiolytic and antidepressant properties, and likewise an effect on diazepam-induced sleep). In the continuation of our investigation of their urinary-metabolite profiles, we performed GC-MS analyses of the diethyl-ether extracts of selected tissues (liver, kidneys, heart, brain, lungs, quadriceps femoris muscle, and spleen) of rats intraperitoneally treated with MMA or IMA (2 g kg−1). Organ-metabolite profiles of MMA and IMA were qualitatively mutually analogous (varying only in the alcohol moiety of the metabolites), and generally analogous to their urinary-metabolite profiles. The greatest diversity and the highest overall amount of anthranilate metabolites was found in the hepatic tissue. The principal anthranilate-related compounds in the organs of rats treated with MMA, among 12 detected, were the products of ester hydrolysis, N -methylanthranilic and anthranilic acids. In the tissues of IMA-treated rats, among 16 compounds, the most abundant ones were the unmetabolized IMA and N -methylanthranilic acid. A collection of the compositional data regarding the anthranilate-related metabolites was statistically treated by multivariate statistical analysis that provided a better insight into the possible biotransformation pathways. Image 1 • Metabolism of methyl (MMA) and isopropyl N -methylanthranilates (IMA) was investigated. • GC-MS analyses of the Et 2 O extracts of the homogenates of the chosen tissues of MMA/IMA-treated rats were performed. • Organ-metabolite profiles of MMA and IMA were qualitatively analogous and analogous to their urinary-metabolite profiles. • Products of ester group hydrolysis and the unmetabolized compounds were the major anthranilates detected in the organs. • Multivariate statistical analysis pinpointed to specific connections between the analyzed xenobiotic metabolites. [ABSTRACT FROM AUTHOR]

Highlights • Metalloproteomic study in muscle samples of fish. • P. squamosissimus (carnivorous species) demonstrate highest mercury concentration. • Nineteen mercury-associated proteins were identified by ESI-MS/MS. • Three protein identified in the protein spots presented mercury biomarkers properties. Abstract Mercury has the ability to bind to a variety of biomolecules, which can compromise its structure and functionality and thus promote its toxic effects. The aim of this study is to identify possible mercury biomarkers in muscle samples of Plagioscion squamosissimus (carnivorous fish) and Colossoma macropomum (omnivorous fish), from the Amazon region. The muscle proteome of fish species was separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), and the total mercury concentrations in protein spots were determined by graphite furnace atomic absorption spectrometry (GFAAS). The protein spots containing mercury were characterized by electrospray ionization tandem mass spectrometry (ESI-MS/MS). The mercury concentrations in the protein spots were in the range of 1.10 ± 0.02–23.90 ± 0.33 μg g−1. The proteins phosphoglycerate mutase 2 (P. squamosissimus), hemoglobin β and cytochrome P450scc (C. macropomum), identified by ESI-MS/MS and showing the highest values of mercury concentration, may be considered possible mercury biomarkers. [ABSTRACT FROM AUTHOR]

Abstract Birds are exposed to many xenobiotics during their lifetime. For accurate prediction of xenobiotic-induced toxic effects on avian species, it is necessary to understand metabolic capacities in a comprehensive range of bird species. However, there is a lack of information about avian xenobiotic metabolizing enzymes (XMEs), particularly in wild birds. Uridine diphosphate glucuronosyltransferase (UGT) is an XME that plays an important role in phase II metabolism in the livers of mammals and birds. This study was performed to determine the characteristics of UGT1E isoform in avian species, those are related to mammals UGT 1A. To understand the characteristics of avian UGT1E isoforms, in vitro metabolic activity and genetic characteristics were investigated. Furthermore, mRNA expression levels of all chicken UGT1E isoforms were measured. On in vitro enzymatic analysis, the white-tailed eagle, great horned owl, and Humboldt penguin showed lower UGT-dependent activity than domestic birds. In synteny analysis, carnivorous birds were shown to have fewer UGT1E isoforms than herbivorous and omnivorous birds, which may explain why they have lower in vitro UGT activity. These observations suggested that raptors and seabirds, in which UGT activity is low, may be at high risk if exposed to elevated levels of xenobiotics in the environment. Phylogenetic analysis suggested that avian UGT1Es have evolved independently from mammalian UGT1As. We identified the important UGT isoforms, such as UGT1E13, and suspected their substrate specificities in avian xenobiotic metabolism by phylogenetic and quantitative real-time PCR analysis. This is the first report regarding the genetic characteristics and interspecies differences of UGT1Es in avian species. Graphical abstract Unlabelled Image Highlights • There is a lack of information about avian xenobiotic metabolizing enzymes (XMEs). • Uridine diphosphate glucuronosyltransferase 1E family (UGT1E) is an XME that plays an important role in phase II metabolism in birds. • Based on in vitro enzymatic analysis, carnivorous birds showed lower UGT1E activity than domestic birds. • Those observations suggested that carnivorous species may be at high risk if exposed to xenobiotics in the environment. [ABSTRACT FROM AUTHOR]

The aryl hydrocarbon receptor (AhR) is a nuclear receptor that facilitates a wide transcriptional response and causes a variety of adaptive and maladaptive physiological functions. Such functions are entirely dependent on the type of ligand activating it, and therefore, the nuances in the activation of this receptor at the single-cell level have become a research interest for different pharmacological and toxicological applications. Here, we investigate the activation of the AhR by diverse classes of compounds in a Hepa1c1c7-based murine hepatoma cell line. The exogenous compounds analyzed produced different levels of ultrasensitivity in AhR activation as measured by XRE-coupled EGFP production and analyzed by both flow cytometric and computational simulation techniques. Interestingly, simulation experiments reported herein were able to reproduce and quantitate the natural single-cell stochasticity inherent to mammalian cell lines as well as the ligand-specific differences in ultrasensitivity. Classical AhR modulators 2,3,7,8-tetrachlorodibenzodioxin (10− 1–105 pM), PCB-126 (10− 1–107 pM), and benzo[a]pyrene (10− 1–107 pM) produced the greatest levels of single-cell ultrasensitivity and most maximal responses, while consumption-based ligands indole-3-carbinol (103–109 pM), 3,3′-diindolylmethane (103–108 pM), and cannabidiol (103–108 pM) caused low-level AhR activation in more purely graded single-cell fashions. All compounds were tested and analyzed over a 24 h period for consistency. The comparative quantitative results for each compound are presented within. This study aids in defining the disparity between different types of AhR modulators that produce distinctly different physiological outcomes. In addition, the simulation tool developed for this study can be used in future studies to predict the quantitative effects of diverse types of AhR ligands in the context of pharmacological therapies or toxicological concerns. [ABSTRACT FROM AUTHOR]

Oxygen is vital for aerobic processes of metabolism and respiration- It has been also implicated in many diseases and degenerative conditions. Free radicals formed from reactive oxygen and nitrogen species act as key players in the initiation and progression of tumor cells and enhance their metastatic potential. The imbalance in the formation and use of free radicals in the tissue creates oxidative stress. Inadequacy in normal cells antioxidant defense system or excessive free radical formation or even both can cause the cell to experience the oxidative stress. This review outlines the involvement of free radicals in different aspects of cancer, from prevention to initiation, progression, treatment and to reduce morbidity and mortality. [ABSTRACT FROM AUTHOR]

The developing immune system is particularly sensitive to immunotoxicants. This study assessed trichloroethylene (TCE)‐induced effects on the gut microbiome and cytokine production during the development in mice. Mice were exposed to TCE (0.05 or 500 μg/mL) at the levels that approximate to environmental or occupational exposure, respectively. Mice were subjected to a continuous developmental exposure to these doses encompassing gestation, lactation and continuing directly in the drinking water postnatally for 154 days (PND154) or PND259. To observe persistence of the effect TCE was removed from the drinking water in a subset of mice on PND154 and were provided regular drinking water until the study terminus (PND259). Abundance of total tissue‐associated bacteria reduced only in mice exposed to TCE until PND259. The ratio of Firmicutes/Bacteroidetes did not alter during this continuos exposure; however, cessation of high‐dose TCE at PND154 resulted in the increased abundance Bacteroidetes at PND259. Furthermore, high‐dose TCE exposure until PND259 resulted in a lower abundance of the genera Bacteroides and Lactobaccilus and increased abundance of genus Bifidobactrium and bacterial family Enterobacteriaceae. TCE exposure until PND154 showed significant changes in the production of interleukin‐33; that might play a dual role in maintaining the balance and homeostasis between commensal microbiota and mucosal health. At PND259, interleukin‐3, granulocyte‐macrophage colony‐stimulating factor and Eotaxin were altered in both, the continuous exposure and cessation groups, whereas only a cessation group had a higher level of KC that may facilitate infiltration of neutrophils. The irreversible effects of TCE after a period of exposure cessation suggested a unique programming and potential toxicity of TCE even at the environmental level exposure. Exposure to trichloroethylene (TCE) with levels relevant to human exposure initiated a shift in the commensal bacterial population and expression of inflammatory response‐related genes in a dose‐dependent manner in an irreversible way. Even after TCE exposure cessation for 105 days, the animals were not able to return to the population distribution found in the control animals as was evident by the shift in the ratio of Bacteroidetes and Firmicutes, and increased abundance of genus Bifidobactrium and bacterial family Enterobacteriaceae. Furthermore, levels of interleukin‐3, granulocyte‐macrophage colony‐stimulating factor and Eotaxin did not reach control levels after the cessation of TCE, thus indicating the irreversible effects of this toxicant at the levels equivalent to environmental exposure. [ABSTRACT FROM AUTHOR]

Maternal adversity and fetal glucocorticoid exposure has long-term effects on cardiovascular, metabolic and behavioral systems in offspring that can persist throughout the lifespan. These data, along with other environmental exposure data, implicate epigenetic modifications as potential mechanisms for long-term effects of maternal exposures on adverse health outcomes in offspring. Advances in microarray, sequencing and bioinformatic approaches have enabled recent studies to examine the genome-wide epigenetic response to maternal adversity. Studies of maternal exposures to xenobiotics such as arsenic and smoking have been performed at birth to examine fetal epigenomic signatures in cord blood relating to adult health outcomes. However, there have been no epigenomic studies examining these effects in animal models. On the other hand, to date, only a few studies of the effects of maternal psychosocial stress have been performed in human infants, and the majority of animal studies have examined epigenomic outcomes in adulthood. In terms of maternal exposure to excess glucocorticoids by synthetic glucocorticoid treatment, there has been no epigenetic study performed in humans and only a few studies undertaken in animal models. This review emphasizes the importance of examining biomarkers of exposure to adversity throughout development to identify individuals at risk and to target interventions. Thus, research performed at birth will be reviewed. In addition, potential subject characteristics associated with epigenetic modifications, technical considerations, the selection of target tissues and combining human studies with animal models will be discussed in relation to the design of experiments in this field of study. [ABSTRACT FROM AUTHOR]

Accounting for genetic and other (eg, underlying disease states) factors that may lead to inter-individual variability in susceptibility to xenobiotic-induced injury is a challenge in human health assessments. A previous study demonstrated that nonalcoholic fatty liver disease (NAFLD), one of the common underlying disease states, enhances tetrachloroethylene (PERC)-associated hepatotoxicity in mice. Interestingly, NAFLD resulted in a decrease in metabolism of PERC to nephrotoxic glutathione conjugates; we therefore hypothesized that NAFLD would protect against PERC-associated nephrotoxicity. Male C57BL/6J mice were fed a low-fat (LFD), high-fat (31% fat, HFD), or high-fat methionine/choline/folate-deficient (31% fat, MCD) diets. After 8 weeks mice were administered either a single dose of PERC (300 mg/kg i.g.) and euthanized at 1–36 h post dose, or five daily doses of PERC (300 mg/kg/d i.g.) and euthanized 4 h after last dose. Relative to LFD-fed mice, HFD- or MCD-fed mice exhibited decreased PERC concentrations and increased trichloroacetate (TCA) in kidneys. S -(1,2,2-trichlorovinyl)glutathione (TCVG), S -(1,2,2-trichlorovinyl)- l -cysteine (TCVC), and N -acetyl- S -(1,2,2,-trichlorovinyl)- l -cysteine (NAcTCVC) were also significantly lower in kidney and urine of HFD- or MCD-fed mice compared with LFD-fed mice. Despite differences in levels of nephrotoxic PERC metabolites in kidney, LFD- and MCD-fed mice demonstrated similar degree of nephrotoxicity. However, HFD-fed mice were less sensitive to PERC-induced nephrotoxicity. Thus, whereas both MCD- and HFD-induced fatty liver reduced the delivered dose of nephrotoxic PERC metabolites to the kidney, only HFD was protective against PERC-induced nephrotoxicity, possibly due to greater toxicodynamic sensitivity induced by methyl and choline deficiency. These results therefore demonstrate that pre-existing disease conditions can lead to a complex interplay of toxicokinetic and toxicodynamic changes that modulate susceptibility to the toxicity of xenobiotics. [ABSTRACT FROM AUTHOR]

The explosive xenobiotic 2,4,6-trinitrotoluene (TNT) is a major worldwide environmental pollutant and its persistence in the environment presents health and environmental concerns. The chemical structure of TNT dictates that biological detoxification pathways follow predominantly reductive transformation of the nitro groups, and as a result, TNT is notoriously recalcitrant to mineralization in the environment. Plant-based technologies to remediate this toxic pollutant rely on a solid understanding of the biochemical detoxification pathways involved. Toward this, two Arabidopsis Tau class glutathione transferases, GSTU24 and GSTU25, have been identified that catalyze the formation of three TNT-glutathionylated conjugates. These two GSTs share 79% identity yet only GSTU25 catalyzes the substitution of a nitro group for sulfur to form 2-glutathionyl-4,6-dinitrotoluene. The production of this compound is of interest because substitution of a nitro group could lead to destabilization of the aromatic ring, enabling subsequent biodegradation. To identify target amino acids within GSTU25 that might be involved in the formation of 2-glutathionyl-4,6-dinitrotoluene, the structure for GSTU25 was determined, in complex with oxidized glutathione, and used to inform site-directed mutagenesis studies. Replacement of five amino acids in GSTU24 established a conjugate profile and activity similar to that found in GSTU25. These findings contribute to the development of plant-based remediation strategies for the detoxification of TNT in the environment. [ABSTRACT FROM AUTHOR]

Melanophryniscus admirabilis (admirable red-belly toad) is a microendemic and critically endangered species found exclusively along 700 m of the Forqueta River, in a fragment of the Atlantic Forest of southern Brazil. One of the greatest concerns regarding the conservation of this species is the extensive use of pesticides in areas surrounding their natural habitat. In recent years, the adaptation and persistence of animal species in human-impacted environments have been associated with microbiota. Therefore, the present study aimed to characterize the oral bacterial community of wild M. admirabilis and to address the question of how this community might contribute to this toad’s adaptation in the anthropogenic environment as well as its general metabolic capabilities. A total of 11 oral samples collected from wild M. admirabilis were characterized and analyzed via high-throughput sequencing. Fragments of the 16S rRNA variable region 4 (V4) were amplified, and sequencing was conducted using an Ion Personal Genome Machine (PGM) System with 316 chips. A total of 181,350 sequences were obtained, resulting in 16 phyla, 34 classes, 39 orders, and 77 families. Proteobacteria dominated (53%) the oral microbiota of toads, followed by Firmicutes (18%), Bacteroidetes (17%), and Actinobacteria (5%). No significant differences in microbial community profile from among the samples were reported, which suggests that the low dietary diversity observed in this population may directly influence the bacterial composition. Inferences of microbiome function were performed using PICRUSt2 software. Important pathways (e.g., xenobiotic degradation pathways for pesticides and aromatic phenolic compounds) were detected, which suggests that the bacterial communities may serve important roles in M. admirabilis health and survival in the anthropogenic environment. Overall, our results have important implications for the conservation and management of this microendemic and critically endangered species.

• 2,4-D concentrations used provoked oxidative stress in shoots but not in roots. • Tomato plants were able to tolerate and conjugate 2,4-D at the shoot level. • It differentially activated protective mechanisms on an organ-dependent manner. • Reduced glutathione was the most important metabolite in response to 2,4-D exposure. In the last 60 years, auxinic herbicides like 2,4-dichlorophenoxyacetic acid (2,4-D) have been among the widest and successful herbicides used in agriculture because it is a selective herbicide that kills dicots and mimics the natural plant phytohormone indol-3-acetic acid (IAA) at the molecular level. In spite of industry attempts to reformulate 2,4-D-based herbicides and reduce their off-target movement, damage has been reported on sensitive plants, like tomato, at low ratesdi. Therefore, it is important to study the responses of such species to such conditions so that yield losses can be avoided or, at least, reduced. It is known that ethylene, abscisic acid (ABA) and reactive oxygen species (ROS) play a central role in 2,4-D toxicity, leading to numerous unbeneficial changes in plant tissues. Yet, how glutathione-related defense- and/or stress-related genes' expressions are affected needs to be more studied. In this study, tomato plants (Solanum lycopersicum L.) were used to determine the expression and participation of the different GST phi class gene family members, plus the plans' antioxidant system, in response to 2,4-D. When tomato plants were root-treated with 2.26 mM 2,4-D for 48 h, H 2 O 2 and O 2 •− levels increased in shoots. Contrarily, in roots, 2,4-D did not provoke clear symptoms of oxidative stress, as lipid peroxidation, H 2 O 2 and O 2 •− levels decreased. Despite the difference in ROS levels observed in both organs, the exposure of tomato plants to 2,4-D lead to the activation of key antioxidant enzymes in both organs, apart from superoxide dismutase (SOD), whose activity increased only in roots, while ascorbate peroxidase (APX) and catalase (CAT) activities increased in both. Also, tomato plants responded to 2.26 mM 2,4-D by increasing Ascorbate (AsA) levels in both organs while an increase in Glutathione (GSH) was only observed in shoots. The herbicide increased both the synthesis and the regeneration of GSH, as well as its usage to conjugate 2,4-D, as shoot γ-glutamyl-cysteinyl synthetase (γ-ECS), glutathione reductase (GR) and glutathione S-transferase (GST) activities increased. Shoot GST increased activity was due to an increased expression of SlGSTF4 and SlGSTF5 , while no SlGSTF s increased their expression in roots. Shoots and roots of tomato plants were differentially affected by 2.26 mM 2,4-D, with 2,4-D detoxification occurring predominantly in leaves, with the specific participation of the GST phi class members SlGSTF4 and SlGSTF5. Also, this study reinforces the notion that the cultivation of tomato in 2,4-D-contaminated soils may result in yield reduction. [ABSTRACT FROM AUTHOR]

ABSTRACT The gut microbiota is susceptible to modulation by environmental stimuli and therefore can serve as a biological sensor. Recent evidence suggests that xenobiotics can disrupt the interaction between the microbiota and host. Here, we describe an approach that combines in vitro microbial incubation (isolated cecal contents from mice), flow cytometry, and mass spectrometry- and 1H nuclear magnetic resonance (NMR)-based metabolomics to evaluate xenobiotic-induced microbial toxicity. Tempol, a stabilized free radical scavenger known to remodel the microbial community structure and function in vivo, was studied to assess its direct effect on the gut microbiota. The microbiota was isolated from mouse cecum and was exposed to tempol for 4 h under strict anaerobic conditions. The flow cytometry data suggested that short-term tempol exposure to the microbiota is associated with disrupted membrane physiology as well as compromised metabolic activity. Mass spectrometry and NMR metabolomics revealed that tempol exposure significantly disrupted microbial metabolic activity, specifically indicated by changes in short-chain fatty acids, branched-chain amino acids, amino acids, nucleotides, glucose, and oligosaccharides. In addition, a mouse study with tempol (5 days gavage) showed similar microbial physiologic and metabolic changes, indicating that the in vitro approach reflected in vivo conditions. Our results, through evaluation of microbial viability, physiology, and metabolism and a comparison of in vitro and in vivo exposures with tempol, suggest that physiologic and metabolic phenotyping can provide unique insight into gut microbiota toxicity. IMPORTANCE The gut microbiota is modulated physiologically, compositionally, and metabolically by xenobiotics, potentially causing metabolic consequences to the host. We recently reported that tempol, a stabilized free radical nitroxide, can exert beneficial effects on the host through modulation of the microbiome community structure and function. Here, we investigated a multiplatform phenotyping approach that combines high-throughput global metabolomics with flow cytometry to evaluate the direct effect of tempol on the microbiota. This approach may be useful in deciphering how other xenobiotics directly influence the microbiota.

Although the human gut microbiome plays a prominent role in xenobiotic transformation, most of the genes and enzymes responsible for this metabolism are unknown. Recently, we linked the two-gene ‘cardiac glycoside reductase’ (cgr) operon encoded by the gut Actinobacterium Eggerthella lenta to inactivation of the cardiac medication and plant natural product digoxin. Here, we compared the genomes of 25 E. lenta strains and close relatives, revealing an expanded 8-gene cgr-associated gene cluster present in all digoxin metabolizers and absent in non-metabolizers. Using heterologous expression and in vitro biochemical characterization, we discovered that a single flavin- and [4Fe-4S] cluster-dependent reductase, Cgr2, is sufficient for digoxin inactivation. Unexpectedly, Cgr2 displayed strict specificity for digoxin and other cardenolides. Quantification of cgr2 in gut microbiomes revealed that this gene is widespread and conserved in the human population. Together, these results demonstrate that human-associated gut bacteria maintain specialized enzymes that protect against ingested plant toxins.