Discharged carbon nanotubes (CNTs) likely interact with co-existing organic contaminants (OCs) and pose joint toxicity to environmental microbes. Herein, hydrophobic pentachlorophenol (PCP) and hydrophilic ciprofloxacin (CIP) were used as representative OCs and their joint toxicities with CNTs to Bacillus subtilis were systematically investigated at cellular, biochemical, and omics levels. The 3-h bacterial growth half inhibitory concentrations of CNTs, PCP, and CIP were 12.5 ± 2.6, 3.5 ± 0.5, and 0.46 ± 0.03 mg/L, respectively, and they all could damage cell membrane, increase intracellular oxidative stress, and alter bacterial metabolomics and transcriptomics; while CNTs-PCP and CNTs-CIP binary exposures exhibited distinct additive and synergistic toxicities, respectively. CNTs increased bacterial bioaccumulation of PCP and CIP via destabilizing and damaging cell membrane. PCP reduced the bioaccumulation of CNTs, while CIP had no significant effect; this difference could be owing to the different effects of the two OCs on cell-surface hydrophobicity and CNTs electronegativity. The additive toxicity outcome upon CNTs-PCP co-exposure could be a result of the balance between the increased toxicity from increased PCP bioaccumulation and the decreased toxicity from decreased CNTs bioaccumulation. The increased bioaccumulation of CIP contributed to the synergistic toxicity upon CNTs-CIP co-exposure, as confirmed by the increased inhibition of topoisomerase Ⅳ activity and interference in gene expressions regulating ABC transporters and lysine biosynthesis. The findings provide novel insights into environmental risks of CNTs.

In this study, we explore whether altered global histone modifications respond to low-level benzene exposure as well as their association with the hematotoxicity. We recruited 147 low-level benzene-exposed workers and 122 control workers from a petrochemical factory in Maoming City, Guangdong Province, China. The internal exposure marker level, urinary S-phenylmercapturic acid (SPMA), in benzene-exposed workers was 1.81-fold higher than that of the controls (P < 0.001). ELISA method was established to examine the specific histone modifications in human peripheral blood lymphocytes (PBLCs) of workers. A decrease in the counts of white blood cells (WBC), neutrophils, lymphocytes, and monocytes appeared in the benzene-exposed group (all P < 0.05) compared to the control group. Global trimethylated histone 3 lysine 4 (H3K4me3) modification was enhanced in the benzene-exposed group (P < 0.05) and was positively associated with the concentration of urinary SPMA (β = 0.103, P = 0.045) and the extent of DNA damage (% Tail DNA: β = 0.181, P = 0.022), but was negatively associated with the leukocyte count (WBC: β = −0.038, P = 0.023). The in vitro study revealed that H3K4me3 mark was enriched in the promoters of several DNA damage responsive (DDR) genes including CRY1, ERCC2, and TP53 in primary human lymphocytes treated with hydroquinone. Particularly, H3K4me3 modification was positively correlated with the expression of CRY1 in the PBLCs of benzene-exposed workers. These observations indicate that H3K4me3 modification might mediate the transcriptional regulation of DDR genes in response to low-dose benzene exposure.

How environmental chemicals can affect and exert their toxic effect at a molecular level has gained significant interest in recent years, not only for understanding their immediate health implications over exposed individuals, but also for their subsequent progeny. Atrazine (ATZ) is a commonly used herbicide in the U.S. and a long-suspected endocrine disrupting chemical. The molecular mechanism conferring long-term adverse health outcomes, however, remain elusive. Here, we explored changes in epigenetic marks that arise after exposure to ATZ at selected doses using image-based analysis coupled with data clustering. Significant decreases in methylated CpG (ᵐᵉCpG) and histone 3 lysine 9 tri-methylated (H3K9me3) were observed in the selected human cell line with a clear spatial preference. Treating cells with ATZ leads to the loss of a subpopulation of cells with high ᵐᵉCpG levels as identified in our clustering and histogram analysis. A similar trend was observed in H3K9me3 potentially attributing to the cross-talking between ᵐᵉCpG and H3K9me3. Changes in ᵐᵉCpG are likely to be associated with alterations in epigenetic enzyme expression levels regulating ᵐᵉCpG and persist after the removal of ATZ source which collectively provide a plausible mechanism for long-term ATZ-induced toxicity.

Hexabromocyclododecane (HBCD), a ubiquitous suspected contaminant, is one of the world's most prominent brominated flame retardants (BFRs). In the present study, earthworms (Eisenia fetida) were exposed to HBCD. The expression of selected antioxidant enzyme genes was measured, and the metabolic responses were assessed using nuclear magnetic resonance (NMR) to identify the molecular mechanism of the antioxidant stress reaction and the metabolic reactions of earthworms to HBCD. A significant up-regulation (p < 0.05) of superoxide dismutase (SOD) gene expression was detected, with the highest gene expression level of SOD appearing at a dose of 400 mg kg⁻¹ dw (2.06-fold, p < 0.01). However, the glutathione transferase (GST) gene expression levels did not differ significantly (p > 0.05). Principal component analysis (PCA) of the metabolic responses showed that all groups could be clearly differentiated, and the highest concentration dose group was the most distant from the control group. Except for fumarate, the measured metabolites, which included adenosine triphosphate (ATP), valine, lysine, glycine, betaine and lactate, revealed significant (p < 0.05) increases after 14 days of exposure to HBCD. HBCD likely induces high levels of anaerobic respiration, which would result in high levels of ATP and lead to the disintegration of proteins into amino acids, including valine and lysine, to produce energy. The observed changes in osmotic pressure were indicative of damage to the membrane structure. Furthermore, this study showed that NMR-based metabolomics was a more sensitive tool than measuring the gene expression levels for elucidating the mode of toxicity of HBCD in earthworm exposure studies.

Arsenic (As) is a highly toxic metalloid adversely affecting the environment, human health, and crop productivity. The present study assessed the synergistic effects of salinity and As on photosynthetic attributes, stomatal regulations, and metabolomics responses of the xero-halophyte Salvadora persica to decipher the As-salinity cross-tolerance mechanisms and to identify the potential metabolites/metabolic pathways involved in cross-tolerance of As with salinity. Salinity and As stress-induced significant stomatal closure in S. persica suggests an adaptive response to decrease water loss through transpiration. NaCl supplementation improved the net photosynthetic rate (by +39%), stomatal conductance (by +190%), water use efficiency (by +55%), photochemical quenching (by +37%), and electron transfer rate (54%) under As stress as compared to solitary As treatment. Our results imply that both stomatal and non-stomatal factors account for a reduction in photosynthesis under high salinity and As stress conditions. A total of 64 metabolites were identified in S. persica under salinity and/or As stress, and up-regulation of various metabolites support early As-salinity stress tolerance in S. persica by improving antioxidative defense and ROS detoxification. The primary metabolites such as polyphenols (caffeic acid, catechin, gallic acid, coumaric acid, rosmarinic acid, and cinnamic acid), amino acids (glutamic acid, cysteine, glycine, lysine, phenylalanine, and tyrosine), citrate cycle intermediates (malic acid, oxalic acid, and α-ketoglutaric acid), and most of the phytohormones accumulated at higher levels under combined treatment of As + NaCl compared to solitary treatment of As. Moreover, exogenous salinity increased glutamate, glycine, and cysteine, which may induce higher synthesis of GSH-PCs in S. persica. The metabolic pathways that were significantly affected in response to salinity and/or As include inositol phosphate metabolism, citrate cycle, glyoxylate and dicarboxylate metabolism, amino acid metabolism, and glutathione metabolism. Our findings indicate that inflections of various metabolites and metabolic pathways facilitate S. persica to withstand and grow optimally even under high salinity and As conditions. Moreover, the addition of salt enhanced the arsenic tolerance proficiency of this halophyte.

It is highly likely that the toxicity of water accommodated fractions (WAF) will influence marine microalgae, and consequently lead to potential risk for the marine ecological environment. However, it was often neglected whether WAF can influence the transformation of relative compounds in organisms. The metabolism of amino acids (AAs) can be used to track physiological changes in microalgae because amino acids are the basis of proteins and enzymes. In this study, using marine Chlorophyta Platymonas helgolandica as the test organism, the effects of different concentrations of WAF on AA compositions and stable carbon isotope ratios (δ¹³C) of individual AAs of Platymonas helgolandica were investigated. The results showed that the WAF of #180 fuel oil had an obvious suppressing effect on the growth and chlorophyll a content of microalgae. The growth inhibitory rate at 96 h was 80.66% at a WAF concentration of 0.50 mg L⁻¹ compared with the control. Furthermore, seven among the 16 AAs, including alanine, cysteine, proline, aspartic acid, lysine, histidine and tyrosine, had relatively high abundance. Under the glycolysis pathway, the cysteine abundance was higher than control, meaning that the biosynthesized pathway of alanine through cysteine as a precursor could be damaged. Phosphoenolpyruvate (PEP) was an important synthesis precursor of alanine (leucine) and aromatic AA family (Phenylalanine and tyrosine), and played an important role in δ¹³CAAₛ fractionation under the WAF stress. Under the TCA pathway, to protect cell metabolism activities under WAF stress, the δ¹³C value of threonine and proline abundance in microalgae with the increase in WAF stress. Therefore, δ¹³CAAₛ fractionation can be used as a novel method for toxicity evaluation of WAF on future.

Overexpression of estrogen receptor β (ERβ) in endometrium contributes to endometriosis (EM) pathogenesis. Trimethylation of the H3 lysine (K) 4 (H3K4me3) in promoters is strongly correlated with gene expression. This study aimed to explore the effects of bisphenol A (BPA) exposure on EM development from the perspective of the regulation of ERβ expression in eutopic endometrium via the H3K4me3-related epigenetic pathway. A mouse EM model was established to investigate the effects of BPA. Immortalized human normal endometrial stromal cells (iESCs) were cultured and treated with BPA to explore the underlying mechanism. Eutopic endometria from patients with or without EM were collected and analyzed. Results showed that BPA elevated ERβ expression in mouse eutopic endometrium and promoted lesion growth. BPA also promoted WD repeat domain 5 (WDR5) expression and upregulated H3K4me3 levels in the ERβ promoter and Exon 1. Further research indicated that WDR5 interacted with tet methylcytosine dioxygenase 2 (TET2), while BPA exposure enhanced the interaction between these two proteins, promoted the recruitment of the WDR5/TET2 complex to the ERβ promoter and Exon 1, and inhibited DNA methylation of CpG islands. The WDR5/TET2 interaction was essential for BPA-induced ERβ overexpression. Enhanced WDR5/TET2 interaction was also observed in eutopic endometria from EM patients. Further results showed that BPA upregulated WDR5 expression through the G protein-coupled estrogen receptor (GPER)-mediated PI3K/mTOR signaling pathway. In conclusion, our study suggests that BPA exposure promotes EM development by upregulating ERβ expression in eutopic endometrium via the WDR5/TET2-mediated epigenetic pathway.

With the open-top chambers (OTCs) in situ in Yangtze River Delta, China in 2007 and 2008, the effects of elevated O3 exposure on nutrient elements and quality of winter wheat and rice grain were investigated. Grain yield per plant of winter wheat and rice declined in both years. The N and S concentrations increased under elevated O3 exposure in both years and C–N ratios decreased significantly. The concentrations of K, Ca, Mg, P, Mn, Cu and Zn in winter wheat and the concentrations of Mg, K, Mn and Cu in rice increased. The concentrations of protein, amino acid and lysine in winter wheat and rice increased and the concentration of amylose decreased. The increase in the nutrient concentration was less than the reduction of grain yield in both winter wheat and rice, and, hence, the absolute amount of the nutrients was reduced by elevated O3.

Heavy metal accumulation in crop grains due to hazardous metal contamination is considered a great concern. However, phytobeneficial fungi are reported to have important abilities for the biosafety of crops grown in contaminated soil. Therefore, the current study was undertaken to explore the mutualistic association of plant growth-promoting endophytic fungi in reducing heavy metal concentration in the seeds of soybean plants subsequently grown in contaminated soil, without comprising seed quality and biochemical profile. The results revealed that endophytic Paecilomyces formosus LHL10 and Penicillium funiculosum LHL06 synergistically produced higher amounts of GAs and IAA in a co-cultured medium. Moreover, the co-inoculation of LHL06 and LHL10 to soybean plants grown under multi-metal toxic conditions significantly mitigated the adverse effects of heavy metal toxicity and increased the seed production (number of pods per plants, number of seeds per pod, and 100 seed weight) of soybean plants grown under control and multi-metal toxic conditions. Moreover, the levels of carbohydrates (glucose, sucrose, and fructose), minerals (iron, calcium, magnesium, and potassium), amino acids (serine, glutamic acids, glycine, methionine, lysine, arginine, and proline), and antioxidants (superoxide dismutase, catalase, and peroxidase) were significantly enhanced in sole and co-inoculated plants under control and stress conditions. Whereas organic acids (citric acid, tartaric acid, malic acid, and succinic acid), lipid peroxidation (MDA) products, multi-metal accumulation (nickel, cadmium, copper, lead, chromium, and aluminum), and stress-responsive endogenous abscisic acid levels were significantly decreased in seeds of soybean plants grown under control and multi-metal toxic conditions upon LHL06 and LHL10 sole and co-inoculation. The current results suggested the positive biochemical regulation in seeds for improving the nutritional status and making it safe for human consumption.

Previous studies have indicated that capsaicin-rich diet and cold weather have shown strong association with tumor incidence. Thus, we investigated the effects of capsaicin and cold exposure in 1,2-dimethylhydrazine (DMH)-induced colorectal cancer as well as the mechanisms underlying capsaicin and cold-induced CRC. Rats were randomly divided into four groups and received cold still water and capsaicin via intragastric gavage until the end of the experiment. The rat’s body weight, thymus weight, and food intakes were assessed. Global levels of histone H3K9, H3K18, H3K27, and H4K16 acetylation and histone deacetylase (HDACs) in colon mucosa were assessed by western blot. Expression levels of Toll-like receptors 2 (TLR2) and Toll-like receptors 4 (TLR4) were measured by western blot and reverse-transcriptase quantitative polymerase chain reaction (qPCR). We found that cold and low-dose capsaicin increased tumor numbers and multiplicity, although there were no differences in tumor incidence. Additionally, rat exposure to cold water and capsaicin display further higher levels of histone H3 lysine 9 (H3K9AC), histone H3 lysine 18 (H3K18AC), histone H3 lysine 27 (H3K27AC), and HDACs compared with the DMH and normal rats. In contrast, a considerable decrease of histone H4 lysine 16 (H4K16AC) was detected in the colon mucosa. Cold and low-dose capsaicin exposure groups were also increased TLR2 and TLR4 protein levels and mRNA levels. These results suggest that chronic cold exposure and capsaicin at a low-dose intervention exacerbate ectopic expression of global histone acetylation and TLR level, which are crucial mechanisms responsible for the progression of colorectal cancer in rats.