Perfluorododecanoic acid (PFDoA), an artificial perfluorochemical, has been widely distributed in different ambient media and has been reported to have the potential to cause developmental neurotoxicity. However, the specific mechanism is largely unknown. In the current study, zebrafish embryos were treated with 0, 0.24, 1.2, and 6 mg/L PFDoA for 120 h. Exposure to PFDoA causes serious decreases in hatching delay, body length, as well as decreased locomotor speed in zebrafish larvae. Additionally, the acetylcholine (ACh) content as well as acetylcholinesterase (AChE) activity were determined to be significantly downregulated in PFDoA treatment groups. The level of dopamine was upregulated significantly after treating with 1.2 and 6 mg/L of PFDoA. Gene expressions related to the nervous system development were also analyzed, with the exception of the gene mesencephalic astrocyte-derived neurotrophic factor (manf), which is upregulated in the 6 mg/L treatment group. All other genes were significantly downregulated in larvae in the PFDoA group in different degrees. In general, the results demonstrated that PFDoA exposure could result in the disruption of the cholinergic system, dopaminergic signaling, and the central nervous system.

Plants have the ability to adapt themselves under stressed conditions through reprogramming their growth and development. Understanding the mechanisms regulating overall growth of stressed plant is an important issue for plant and environmental biology research. Although the role of NO in modulating arsenic (As) toxicity is known, nitric oxide (NO) induced alteration in auxin and nutrient related transporters during As stress in rice is poorly understood. Experimental results showed that As exposure decreased gene expression level of polar auxin transporter (PIN proteins), and nutrient transporter related genes (AMT, NRT, NiR, PHT, KTP). The improved tolerance induced by As + NO combination is attributed to reduced As accumulation in rice seedlings, improved root architectural changes, overall growth of plant, chlorophyll, protein content, and accumulation of mineral nutrients by reducing the ROS generation. Further, enhanced transcript levels of PIN proteins and mineral nutrition related genes were also observed under As + NO treatment. Additional biochemical data revealed enhanced oxidative stress by increasing the level of antioxidant enzymes, and stress-related parameters. Overall, the study provides an integrated view of plant response during As + NO interaction to change the plant metabolism through different cellular processes.

Propranolol (PRO), a human β-AR (β-adrenergic receptor) antagonist, is considered to result in specific effects in a non-target species, D. magna, based on our previous studies. The present study investigated the effects of β-AR agents, including an antagonist and agonist using pharmacologically relevant endpoints as well as a more holistic gene expression approach to reveal the impacts and potential mode of actions (MOAs) in the model non-target species. Results show that the responses in cardiac endpoints and gene expression in D. magna are partially similar but distinguishable from the observations in different organisms. No effect was observed on heart size growth in PRO and isoprenaline (ISO) exposure. The contraction capacity of the heart was decreased in ISO exposure, and the heart rate was decreased in PRO exposure. Time-series exposures showed different magnitudes of effect on heart rate and gene expression dependent on the type of chemical exposure. Significant enrichment of gene families involved in protein metabolism and biotransformation was observed within the differentially expressed genes, and we also observed differential expression in juvenile hormone-inducible proteins in ISO and PRO exposure, which is suspected of having endocrine disruption potential. Taken together, deviation between the effects of PRO and ISO in D. magna and other organisms suggests dissimilarity in MOAs or attributes of target bio-molecules between species. Additionally, PRO and ISO may act as endocrine disruptors based on the gene expression observation. Results in the present study confirm that it is challenging to predict ecological impact of active pharmaceutical ingredients (APIs) based on the available data acquired through human-focused studies. Furthermore, the present study provided unique data and a case study on the impact of APIs in a non-target organism.

Diclofenac (DCF) has been recognized as an emerging contaminant in aquatic environments. Though many studies have investigated the toxic effects of DCF in human and mammals, limited information is available for the responses of genes associated with detoxification metabolisms in non-target aquatic organisms such as fish. In the present study, a small benthic fish Mugilogobius abei, was chosen as the test organism and the effects of DCF on detoxification-related genes at transcriptional level in M. abei were investigated. Partial cDNAs of pregnane-X-receptor (pxr), cytochrome P450 3A (cyp 3a) and alpha-gst were cloned firstly. The responses of cyp 1a, cyp 3a, alpha-gst and p-gp genes and associated microRNAs expressions were measured under different concentrations of DCF exposure (0.5, 5, 50, 500 μg/L) for 24 h and 168 h. Induction of cyp 1a, cyp 3a, alpha-gst, p-gp and pxr mRNA expressions was observed under DCF exposure for different time. Positive concentration-response relationships between DCF concentrations and cyp 1a as well as alpha-gst mRNA expression were observed under DCF exposure for 24 h. The similar trend between pxr mRNA expression and cyp 3a gene expression suggested the role of pxr in regulation of its downstream detoxification genes involved in DCF detoxification in M. abei. The negative correlation between miR-27a and p-gp expression under DCF exposure for 24 h indicated the role of miRNA in post transcriptional regulation on detoxification-related genes mRNAs in M. abei exposed to DCF. Overall, DCF exposure, even at environmental levels, may interrupt the responses of the detoxification genes in M. abei, which may affect the response of the exposed organism to other pollutants. This work provides implications on the bio-monitoring and risk assessment of DCF in aquatic ecosystems by using of local native fish species.

Tetrabromobisphenol A (TBBPA) and tetrachlorobisphenol A (TCBPA) are persistent toxic environmental pollutants that cause severe reproductive toxicity in animals. The goal of this study was to compare the reproductive toxic effects of TBBPA and TCBPA on male Rana nigromaculata and to expound on the mechanisms leading to these effects. Healthy adult frogs were exposed to 0, 0.001, 0.01, 0.1, and 1 mg/L of TBBPA and TCBPA for 14 days. Sperm numbers were counted by erythrometry. Sperm mobility and deformities were observed under a light microscope (400 ×). We used commercial ELISA kits to determine the serum content of testosterone (T), estradiol (E2), luteinizing hormone (LH) and follicle stimulating hormone (FSH). Expression of androgen receptor (AR) mRNA was detected using real-time qPCR. Sperm numbers and sperm mobility were significantly decreased and sperm deformity was significantly increased in a concentration dependent manner following exposure to TBBPA and TCBPA. Sperm deformity was significantly greater in the 1 mg/L TCBPA (0.549) treatment group than in the 1 mg/L TBBPA (0.397) treatment group. Serum T content was significantly greater in the 0.01, 0.1 and 1 mg/L TBBPA and TCBPA experimental groups compared with controls, while E2 content was significantly greater in only the 1 mg/L TBBPA and TCBPA experimental groups. Expression levels of LH and FSH significantly decreased in the 1 mg/L TBBPA and TCBPA treatment groups. AR mRNA expression decreased markedly in all the treated groups. Our results indicated that TBBPA and TCBPA induced reproductive toxicity in a dose-dependent manner, with TCBPA having greater toxicity than TBBPA. Furthermore, changes in T, E2, LH, and FSH levels induced by TBBPA and TCBPA exposure, which led to endocrine disorders, also caused disturbance of spermatogenesis through abnormal gene expressions of AR in the testes.

Assessing the toxicity posed by mixtures of unknown chemicals to aquatic organisms is challenging. In this study, water samples from six cross-sections along the Xitiaoxi River Basin (XRB) were monthly or bimonthly collected in 2014. The year-period physiochemical parameters as well as one-month-water sample based acute biotoxicity tests showed that the river water quality of the year was generally in a good status. High performance liquid chromatography (HPLC) screening based on one-month-water samples suggested that the organic pollutants might be non-to-moderately-polar chemicals in very low concentrations. One-month-water sample based RNA-seq was performed to measure the mRNA differential expression profile of zebrafish larvae to furtherly explore the potential bioeffect and the spatial water quality change of the river. Result indicated that the number of deferentially expressed genes (DEGs) tended to increase along the downstream direction of the river. Gene ontology (GO) enrichment analysis implied that the key pollutants might mainly be the function disruptors of biological processes. Principle components analysis (PCA) combining with transcripts and one-month-water sample based physiochemical parameters indicated that the pollution might be similar at TP, DP and CTB sites while pollution homology existed on some extent between YBQ and JW sites. Although the water quality of the river had a complex time-space alternation during the year, and the one-month-data based RNA-seq could not reflex the whole year-water quality of a watershed, the gene expression profile via RNA-seq provided an alternative way for assessing integrated biotoxicity of surface water, and it was relatively fit for early-warning of water quality of a watershed with unobservable acute toxicity. However, the identification of detail toxicants and the links between DEGs and pollution level as well as physiological-biochemical toxicity needed further investigation.

To examine the mechanism of hexavalent chromium [Cr(VI)]-induced carcinogenesis, a cross-sectional study in workers with or without exposure to Cr(VI) as well as in vitro administration of Cr(VI) in 16HBE cells was conducted. We explored the associations between Cr(VI) exposure, methylation modification of DNA repair genes and their expression levels, and genetic damage. Results showed that hypermethylation of CpG sites were observed in both occupationally exposed workers and 16HBE cells administrated Cr(VI). DNA damage markers including 8-hydroxydeoxyguanosine (8-OHdG) and micronucleus frequency in Cr(VI)-exposed workers were significantly higher than the control group. Among workers, blood Cr concentration was positively correlaed with the methylation level of CpG sites in DNA repair genes including CpG6,7, CpG8, CpG9,10,11 of MGMT, CpG11 of HOGG1; CpG15,16,17, CpG19 of RAD51, and genetic damage markers including 8-OHdG and micronucleus frequency. Significant negative association between methylation levels of CpG sites in DNA repair genes and corresponding mRNA was also observed in 16HBE cells. This indicated that Cr(VI) exposure can down-regulate DNA repair gene expression by hypermethylation, which leads to enhanced genetic damage. The methylation level of these CpG sites of DNA repair genes can be potential epigenetic markers for Cr(VI)-induced DNA damage.

The gut microbiome is sensitive to diet and environmental exposures and is involved in the regulation of host metabolism. Additionally, gut inflammation is an independent risk factor for the development of metabolic diseases, specifically atherosclerosis and diabetes. Exposures to dioxin-like pollutants occur primarily via ingestion of contaminated foods and are linked to increased risk of developing cardiometabolic diseases. We aimed to elucidate the detrimental impacts of dioxin-like pollutant exposure on gut microbiota and host gut health and metabolism in a mouse model of cardiometabolic disease. We utilized 16S rRNA sequencing, metabolomics, and regression modeling to examine the impact of PCB 126 on the microbiome and host metabolism and gut health. 16S rRNA sequencing showed that gut microbiota populations shifted at the phylum and genus levels in ways that mimic observations seen in chronic inflammatory diseases. PCB 126 reduced cecum alpha diversity (0.60 fold change; p = 0.001) and significantly increased the Firmicutes to Bacteroidetes ratio (1.63 fold change; p = 0.044). Toxicant exposed mice exhibited quantifiable concentrations of PCB 126 in the colon, upregulation of Cyp1a1 gene expression, and increased markers of intestinal inflammation. Also, a significant correlation between circulating Glucagon-like peptide-1 (GLP-1) and Bifidobacterium was evident and dependent on toxicant exposure. PCB 126 exposure disrupted the gut microbiota and host metabolism and increased intestinal and systemic inflammation. These data imply that the deleterious effects of dioxin-like pollutants may be initiated in the gut, and the modulation of gut microbiota may be a sensitive marker of pollutant exposures.

Adverse effect studies of gasoline exhaust are scarce, even though gasoline direct injection (GDI) vehicles can emit a high number of particles.The aim of this study was to conduct an in vitro hazard assessment of different GDI exhausts using two different cell culture models mimicking the human airway. In addition to gasoline particle filters (GPF), the effects of two lubrication oils with low and high ash content were assessed, since it is known that oils are important contributors to exhaust emissions.Complete exhausts from two gasoline driven cars (GDI1 and GDI2) were applied for 6 h (acute exposure) to a multi-cellular human lung model (16HBE14o-cell line, macrophages, and dendritic cells) and a primary human airway model (MucilAir™). GDI1 vehicle was driven unfiltered and filtered with an uncoated and a coated GPF. GDI2 vehicle was driven under four settings with different fuels: normal unleaded gasoline, 2% high and low ash oil in gasoline, and 2% high ash oil in gasoline with a GPF. GDI1 unfiltered was also used for a repeated exposure (3 times 6 h) to assess possible adverse effects.After 6 h exposure, no genes or proteins for oxidative stress or pro-inflammation were upregulated compared to the filtered air control in both cell systems, neither in GDI1 with GPFs nor in GDI2 with the different fuels. However, the repeated exposure led to a significant increase in HMOX1 and TNFa gene expression in the multi-cellular model, showing the responsiveness of the system towards gasoline engine exhaust upon prolonged exposure.The reduction of particles by GPFs is significant and no adverse effects were observed in vitro during a short-term exposure. On the other hand, more data comparing different lubrication oils and their possible adverse effects are needed. Future experiments also should, as shown here, focus on repeated exposures.

Bisphenol A (BPA) exposure receives great ecotoxicological concern. However, gaps in knowledge, such as metabolism of BPA and inconsistent reports on reproductive toxicity, still exist. In this study, a marine fish model (Oryzias melastigma) was exposed to serial concentrations of BPA throughout its whole life cycle. The level of BPA-glucuronide (BPAG) dramatically increased throughout the embryonic stage since 4 dpf. Accordingly, the mRNA level and enzymatic activity of UDP-glucuronosyltransferases (UGTs) increased across the embryonic stage. The mRNA level of UGT2 subtype rather than UGT1 or UGT5 showed a concentration dependent response to BPA exposure. BPA exposure led to the morphological disruption of the chorion and villi as shown by scanning electron microscopy; however, the hatchability was not significantly influenced after exposure. Newly hatching larvae were continuously exposed to BPA for 120 days. Lower mRNA levels of hormone metabolism-related genes, decreased ratio of E2/T, slower ovary development and decreased egg production confirmed the inhibitory effect of BPA on reproduction. Overall, our results showed the conjugation of BPA into BPAG by UGT2 at the embryonic stage and convinced the reproductive toxicity from multiple levels after whole life exposure to BPA.