Adverse effects of coal combustion related fine particulate matter (PM2.5) on nematode Caenorhabditis elegans

Acute exposure to seasonal PM2.5 induces toxicological responses in A549 cells cultured at the air-liquid interface mediated by oxidative stress and endoplasmic reticulum stress

Atmospheric fine particulate matter (PM2.5) enters the human body through respiration and poses a threat to human health. This is not only dependent on its mass concentration in the atmosphere, but also related to seasonal variations in its chemical components, which makes it important to study the cytotoxicity of PM2.5 in different seasons. Traditional immersion exposure cannot simulate the living environment of human epithelial cells in the human body, making this method unsuitable for evaluating the inhalation toxicity of PM2.5. In this study, a novel air-liquid interface (ALI) particulate matter exposure device (VITROCELL Cloud 12 system) was used to evaluate the toxic effects and potential mechanisms of human lung epithelial cells (A549) after exposure to seasonal PM2.5. PM2.5 samples from four seasons were collected and analyzed for chemical components. After 6 h of exposure to seasonal PM2.5, winter PM2.5 exhibited the highest cytotoxicity among most toxicity indicators, especially apoptosis rate, reactive oxygen species (ROS), inflammatory responses and DNA damage (γ-H2AX). The effect of autumn PM2.5 on apoptosis rate was significantly higher than that in spring, and there was no significant difference in other toxicity indicators between spring and autumn. The cytotoxicity of summer PM2.5 was the lowest among the four seasons. It should be noted that even exposure to low doses of summer PM2.5 leads to significant DNA damage in A459 cells. Correlation analysis results showed that water-soluble ions, metallic elements, and polycyclic aromatic hydrocarbons (PAHs) were associated with most toxicological endpoints. Inhibitors of oxidative stress and endoplasmic reticulum (ER) stress significantly inhibited cellular damage, indicating that PM2.5-induced cytotoxicity may be related to the generation of ROS and ER stress. In addition, PM2.5 can induce ER stress through oxidative stress, which ultimately leads to apoptosis.

Differential impact of diesel exhaust particles on glutamatergic and dopaminergic neurons in Caenorhabditis elegans: A neurodegenerative perspective

The growing body of evidence links exposure to particulate matter pollutants with an increased risk of neurodegenerative diseases. In the present study, we investigated whether diesel exhaust particles can induce neurobehavioral alterations associated with neurodegenerative effects on glutamatergic and dopaminergic neurons in Caenorhabditis elegans (C. elegans). Exposure to DEP at concentrations of 0.167 µg/cm2 and 1.67 µg/cm2 resulted in significant developmental delays and altered locomotion behaviour. These effects were accompanied by discernible alterations in the expressions of antioxidant genes sod-3 and gst-4 observed in transgenic strains. Behaviour analysis demonstrated a significant reduction in average speed (p < 0.001), altered paths, and decreased swimming activities (p < 0.01), particularly at mid and high doses. Subsequent assessment of neurodegeneration markers in glutamatergic (DA1240) and dopaminergic (BZ555) transgenic worms revealed notable glutamatergic neuron degeneration at 0.167 μg/cm2 (∼30 % moderate, ∼20 % advanced) and 1.67 μg/cm2 (∼28 % moderate, ∼24 % advanced, p < 0.0001), while dopaminergic neurons exhibited structural deformities (∼16 %) without significant degeneration in terms of blebs and breaks. Furthermore, in silico docking simulations suggest the presence of an antagonistic competitive inhibition induced by DEP in the evaluated neuro-targets, stronger for the glutamatergic transporter than for the dopaminergic receptor from the comparative binding affinity point of view. The results underscore DEP's distinctive neurodegenerative effects and suggest a link between locomotion defects and glutamatergic neurodegeneration in C. elegans, providing insights into environmental health risks assessment.

Toxicological responses of A549 and HCE-T cells exposed to fine particulate matter at the air-liquid interface

Fine particulate matter (PM2.5) can enter the human body in various ways and have adverse effects on human health. Human lungs and eyes are exposed to the air for a long time and are the first to be exposed to PM2.5. The "liquid immersion exposure method" has some limitations that prevent it from fully reflecting the toxic effects of particulate matter on the human body. In this study, the collected PM2.5 samples were chemically analyzed. An air-liquid interface (ALI) model with a high correlation to the in vivo environment was established based on human lung epithelial cells (A549) and immortalized human corneal epithelial cells (HCE-T). The VITROCELL Cloud 12 system was used to distribute PM2.5 on the cells evenly. After exposure for 6 h and 24 h, cell viability, apoptosis rate, reactive oxygen species (ROS) level, expression of inflammatory factors, and deoxyribonucleic acid (DNA) damage were measured. The results demonstrated significant dose- and time-dependent effects of PM2.5 on cell viability, cell apoptosis, ROS generation, and DNA damage at the ALI, while the inflammatory factors showed dose-dependent effects only. It should be noted that even short exposure to low doses of PM2.5 can cause cell DNA double-strand breaks and increased expression of γ-H2AX, indicating significant genotoxicity of PM2.5. Increased abundance of ROS in cells plays a crucial role in the cytotoxicity induced by PM2.5 exposure These findings emphasize the significant cellular damage and genotoxicity that may result from short-term exposure to low levels of PM2.5.

Comparative toxicity of coal and coal ash: Assessing biological impacts and potential mechanisms through in vitro and in vivo testing

BACKGROUND

Coal and coal ash present inorganic elements associated with negative impacts on environment and human health. The objective of this study was to compare the toxicity of coal and coal ash from a power plant, assess their inorganic components, and investigate the biological impacts and potential mechanisms through in vitro and in vivo testing.

METHODS

Particle-Induced X-ray Emission method was used to quantify inorganic elements and the toxicity was evaluated in Caenorhabditis elegans and Daphnia magna in acute and chronic procedures. The genotoxic potential was assessed using alkaline and FPG-modified Comet assay in HepG2 cells and mutagenicity was evaluated using Salmonella/microsome assay in TA97a, TA100, and TA102 strains.

RESULTS

Inorganic elements such as aluminum (Al) and chromium (Cr) were detected at higher concentrations in coal ash compared to coal. These elements were found to be associated with increased toxicity of coal ash in both Caenorhabditis elegans and Daphnia magna. Coal and coal ash did not induce gene mutations, but showed genotoxic effects in HepG2 cells, which were increased using the FPG enzyme, indicating DNA oxidative damage.

CONCLUSIONS

The combined findings from bioassays using C. elegans and D. magna support the higher toxicity of coal ash, which can be attributed to its elevated levels of inorganic elements. The genotoxicity observed in HepG2 cells confirms these results. This study highlights the need for continuous monitoring in areas affected by environmental degradation caused by coal power plants. Additionally, the analysis reveals significantly higher concentrations of various inorganic elements in coal ash compared to coal, providing insight into the specific elemental composition contributing to its increased toxicity.

Ecotoxicity induced by total, water soluble and insoluble components of atmospheric fine particulate matter exposure in Caenorhabditis elegans

Although PM_2.5 could cause toxicity in environmental organisms, the toxicity difference of PM_2.5 under different solubilities is still poorly understood. To acquire a better knowledge of the ecotoxicity of PM_2.5 under different solubilities, the model animal Caenorhabditis elegans (C. elegans) was exposed to Total-PM_2.5, water insoluble components of PM_2.5 (WIS-PM_2.5) and water soluble components of PM_2.5 (WS-PM_2.5). The physiological (growth, locomotion behavior, and reproduction), biochemical (germline apoptosis, and reactive oxygen species (ROS) production) indices, and the related gene expression were examined. According to the findings, acute exposure to these three components caused adverse physiological effects on growth and locomotion behavior, and significantly induced germline apoptosis or ROS production. In contrast, prolonged exposure showed stronger adverse effects than acute exposure. Additionally, the results of multiple toxicological endpoints showed that the toxicity effects of WIS-PM_2.5 are more intense than WS-PM_2.5, which means that insoluble components contributed more to the toxicity of PM_2.5. Prolonged exposure to 1000 mg/L WS-PM_2.5, WIS-PM_2.5, and Total-PM_2.5 dramatically altered the expression of stress-related genes, which further indicated that apoptosis, DNA damage and oxidative stress play a crucial part in toxicity induced by PM_2.5.

Long-term exposure to tire-derived 6-PPD quinone causes intestinal toxicity by affecting functional state of intestinal barrier in Caenorhabditis elegans

2-((4-Methylpentan-2-yl)amino)-5-(phenylamino)cyclohexa-2,5-diene-1,4-dione (6-PPDQ) is the ozonation product of 6-PPD, a commonly used tire preservative. Although the 6-PPDQ has been frequently detected in different environmental ecosystems, its long-term effects on organisms remain still largely unknown. We here used Caenorhabditis elegans as an experimental animal to investigate the toxic effect of prolonged exposure to 6-PPDQ (0.1-100 μg/L). After the exposure, we found that 100 μg/L 6-PPDQ caused the lethality. We further selected concentrations of 0.1-10 μg/L to examine the possible intestinal toxicity induced by 6-PPDQ. Although 0.1-10 μg/L 6-PPDQ could not influence intestinal morphology, the intestinal permeability was significantly enhanced by 1-10 μg/L 6-PPDQ as indicated by erioglaucine disodium staining. In addition, the expression of intestinal fatty acid transporter ACS-22 governing functional state of intestinal barrier was decreased by exposure to 1-10 μg/L 6-PPDQ. Meanwhile, intestinal reactive oxygen species (ROS) production was induced by 0.1-10 μg/L 6-PPDQ and lipofuscin accumulation reflected by intestinal autofluorescence was activated by 1-10 μg/L 6-PPDQ. Accompanied with activation of intestinal oxidative stress, expressions of some anti-oxidation related genes (ctl-2, sod-2, sod-3, and sod-4) were significantly increased by 0.1-10 μg/L 6-PPDQ. Moreover, intestinal RNAi of acs-22 strengthened the susceptibility of nematodes to intestinal toxicity of 6-PPDQ. Therefore, considering that the environmentally relevant concentrations of 6-PPDQ were ≤10 μg/L, our data suggested that long-term exposure to 6-PPDQ at environmentally relevant concentrations potentially results in intestinal toxicity by disrupting functional state of intestinal barrier in organisms.

PM2.5 induce lifespan reduction, insulin/IGF-1 signaling pathway disruption and lipid metabolism disorder in Caenorhabditis elegans

Introduction

Exposure to fine particulate matter (PM), especially PM_2.5, can induce various adverse health effects in populations, including diseases and premature death, but the mechanism of its toxicity is largely unknown.

Methods

Water-soluble components of PM_2.5 (WS-PM_2.5) were collected in the north of China in winter, and combined in two groups with the final concentrations of 94 μg/mL (C_L group, AQI ≤ 100) and 119 μg/mL (C_H group, 100 < AQI ≤ 200), respectively. The acute and long-term toxic effects of WS-PM_2.5 samples were evaluated in several aspects such as development, lifespan, healthspan (locomotion behavior, heat stress tolerance, lipofucin). DAF mutants and genes were applied to verify the action of IIS pathway in WS-PM_2.5 induced-effects. RNA-Sequencing was performed to elucidate the molecular mechanisms, as well as ROS production and Oil red O staining were also served as means of mechanism exploration.

Results

Body length and lifespan were shortened by exposure to WS-PM_2.5. Healthspan of nematodes revealed adverse effects evaluated by head thrash, body bend, pharyngeal pump, as well as intestinal lipofuscin accumulation and survival time under heat stress. The abbreviated lifespan of daf-2(e1370) strain and reduced expression level of daf-16 and hsp-16.2 indicated that IIS pathway might be involved in the mechanism. Thirty-five abnormally expressed genes screened out by RNA-Sequencing techniques, were functionally enriched in lipid/lipid metabolism and transport, and may contribute substantially to the regulation of PM_2.5 induced adverse effects in nematodes.

Conclusion

WS-PM_2.5 exposure induce varying degrees of toxic effects, such as body development, shorten lifespan and healthspan. The IIS pathway and lipid metabolism/transport were disturbed by WS-PM_2.5 during WS-PM_2.5 exposure, suggesting their regulatory role in lifespan determination.

Zn2+ loading as a critical contributor to the circ_0008553-mediated oxidative stress and inflammation in response to PM2.5 exposures

Inflammation is a major adverse outcome induced by inhaled particulate matter with a diameter of ≤ 2.5 µm (PM_2.5), and a critical trigger of most PM_2.5 exposure-associated diseases. However, the key molecular events regulating the PM_2.5-induced airway inflammation are yet to be elucidated. Considering the critical role of circular RNAs (circRNAs) in regulating inflammation, we predicted 11 circRNAs that may be involved in the PM_2.5-induced airway inflammation using three previously reported miRNAs through the starBase website. A novel circRNA circ_0008553 was identified to be responsible for the PM_2.5-activated inflammatory response in human bronchial epithelial cells (16HBE) via inducing oxidative stress. Using a combinatorial model PM_2.5 library, we found that the synergistic effect of the insoluble core and loaded Zn²⁺ ions at environmentally relevant concentrations was the major contributor to the upregulation of circ_0008553 and subsequent induction of oxidative stress and inflammation in response to PM_2.5 exposures. Our findings provided new insight into the intervention of PM_2.5-induced adverse outcomes.

Chemical Composition and Transgenerational Effects on Caenorhabditis elegans of Seasonal Fine Particulate Matter

While numerous studies have demonstrated the adverse effects of fine particulate matter (PM) on human health, little attention has been paid to its impact on offspring health. The multigenerational toxic effects on Caenorhabditis elegans (C. elegans) were investigated by acute exposure. PM_2.5 and PM₁ samples were collected and analysed for their chemical composition (inorganic ions, metals, OM, PAHs) in different seasons from April 2019 to January 2020 in Lin'an, China. A higher proportion of organic carbon components (34.3%, 35.9%) and PAHs (0.0144%, 0.0200%) occupied the PM_2.5 and PM₁ samples in winter, respectively. PM₁ in summer was enriched with some metal elements (2.7%). Exposure to fine PM caused developmental slowing and increased germ cell apoptosis, as well as inducing intestinal autofluorescence and reactive oxygen species (ROS) production. PM₁ caused stronger toxic effects than PM_2.5. The correlation between PM component and F0 generation toxicity index was analysed. Body length, germ cell apoptosis and intestinal autofluorescence were all highly correlated with Cu, As, Pb, OC and PAHs, most strongly with PAHs. The highest correlation coefficients between ROS and each component are SO₄^2- (R = 0.743), Cd (R = 0.816) and OC (R = 0.716). The results imply that OC, PAHs and some transition metals play an important role in the toxicity of fine PM to C. elegans, where the organic fraction may be the key toxicogenic component. The multigenerational studies show that PM toxicity can be passed from parent to offspring, and gradually returns to control levels in the F3-F4 generation with germ cell apoptosis being restored in the F4 generation. Therefore, the adverse effects of PM on reproductive damage are more profound.

Reproductive toxicity and underlying mechanisms of fine particulate matter (PM2.5) on Caenorhabditis elegans in different seasons

Although numerous studies have investigated that atmospheric fine particulate matter (PM_2.5) can be toxic to environmental organisms, the research on the reproductive toxicity of PM_2.5 is limited, and the key toxic components and underlying mechanisms remain unknown. In this work, PM_2.5 samples of four seasons in Nanjing from March 1, 2021, to February 28, 2022 were collected and the chemical components were analyzed. Caenorhabditis elegans (C. elegans) was employed to conduct the toxicological testing. The reproductive toxicity of PM_2.5 to C. elegans in different seasons was evaluated by multiple reproductive endpoints. Exposure to high concentrations of PM_2.5 significantly decreased the brood size and the number of fertilized eggs in utero. PM_2.5 exposure also increased the number of germ cell corpses and caused abnormal expression of apoptosis-related genes (ced-9, ced-4, and ced-3), which confirmed that PM_2.5 induced germline apoptosis. In addition, PM_2.5 exposure significantly increased the production of reactive oxygen species (ROS) in C. elegans and the fluorescence intensity of HUS-1 protein in of transgenic strain WS1433. Meanwhile, the expression of genes related to DNA damage (cep-1, clk-2, egl-1, and hus-1) and oxidative stress (mev-1, isp-1, and gas-1) also significantly altered in C. elegans, suggesting induction of DNA damage and oxidative stress. According to Pearson correlation analyses, DNA damage and oxidative stress were significantly correlated with multiple reproductive endpoints in C. elegans. Thus, it was speculated that PM_2.5 caused reproductive dysfunction and germ cell apoptosis in C. elegans may be by inducing ROS and DNA damage. In addition, heavy metals in PM_2.5 were significantly correlated with multiple endpoints at physiological and biochemical, suggesting that the heavy metals might be an important contributor to the reproductive toxicity induced by PM_2.5.

A comparison of fine particulate matter (PM2.5) in vivo exposure studies incorporating chemical analysis

The complex, variable mixtures present in fine particulate matter (PM_2.5) have been well established, and associations between chemical constituents and human health are expanding. In the past decade, there has been an increase in PM_2.5 toxicology studies that include chemical analysis of samples. This investigation is a crucial component for identifying the causal constituents for observed adverse health effects following exposure to PM_2.5. In this review, investigations of PM_2.5 that used both in vivo models were explored and chemical analysis with a focus on respiratory, cardiovascular, central nervous system, reproductive, and developmental toxicity was examined to determine if chemical constituents were considered in the interpretation of the toxicity findings. Comparisons between model systems, PM_2.5 characteristics, endpoints, and results were made. A vast majority of studies observed adverse effects in vivo following exposure to PM_2.5. While limited, investigations that explored connections between chemical components and measured endpoints noted significant associations between biological measurements and a variety of PM_2.5 constituents including elements, ions, and organic/elemental carbon, indicating the need for such analysis. Current limitations in available data, including relatively scarce statistical comparisons between collected toxicity and chemical datasets, are provided. Future progress in this field in combination with epidemiologic research examining chemical composition may support regulatory standards of PM_2.5 to protect human health.

Using homing pigeons to monitor atmospheric organic pollutants in a city heavily involving in coal mining industry

Coal is the most extensively used fossil fuel in China. It is well documented that coal combustion detrimentally affected air quality, yet the contribution of coal mining activity to air pollution is still largely unknown. Homing pigeons have been applied to assess the occurrence of atmospheric pollutants within cities. Herein, we sampled homing pigeons from both urban and mining areas in a typical coal industry city (Datong, China) as biomonitors for assessing local air pollution. Target organic contaminants, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs) were frequently detected in lung, liver, and fat tissues of the pigeons. The pollutants were predominately accumulated in lung, validating that respiration was the main accumulation route for these compounds in homing pigeons. In addition, pathological damage examination in lung and liver tissues revealed that the exposure to atmospheric pollutants impaired pigeon health. While the concentrations of PCBs and OCPs were similar in pigeons from urban and mining areas, the concentrations of PAHs were higher in pigeons from urban area. In contrast, more elevated levels of PBDEs (particularly BDE-209) were found in the mining area, which was consistent with the greater pathological damages and particulate matter levels. Unlike coal combustion, coal mining activities did not increase atmospheric PAH exposure to homing pigeons, but intensified PBDE contamination along with increasing emission of particulate matters. Overall, homing pigeons are promising biomonitors for assessing the respiratory exposure and risk of atmospheric pollutants within cities.

Phenotypic changes of Trichinella spiralis treated by Commiphora molmol,Lepidium sativum, and Albendazole: in vitro study

Trichinellosis is a nematode-causing disease distinguished by its continuous transmission in the carnivores and omnivores. Despite effective eradication of the enteral forms, conventional drugs fail to eliminate the migrating and muscle ones. Over the past years, researchers intensified the work on herbal medicines as alternatives or aids to albendazole, the reference drug. This research hypothesizes that the therapeutic agent absorption route could be an evidence-based carrier molecule or auxiliary drug to albendazole. Accordingly, this in vitro study was designed to investigate mainly the phenotypic changes induced by a mono-treatment of albendazole, Lipidium sativum (garden cress), and Commiphora molmol (myrrh). Incredibly, no data were reported on the morphological alterations of T. spiralis larvae treated by any of these drugs. The experimental design tested various concentrations (25, 50, 100, and 200 μg/ml) of each herbal medicine for the lethal effects on the parasite forms for a day (1, 12, and 24h). The data showed that the highest significant mortality rate of the parasite forms was in favor of the concentration 200 μg/ml of both plant extracts in a time-dependent manner. Therefore, albendazole at 200 μg/ml dose was tested in parallel, and all experimental groups were compared to non-treated muscle larvae and worms. Albendazole-treated worms accounted for the least significant (p<0.001) survival rate (2 %), followed by myrrh (5 %), and the adverse was valid for the survival rate of the muscle larvae at that time. None of the larvae/worms was alive after 24 hours of incubation with the 200μg/ml of either treatment. The scanning electron microscope investigation of the experimental groups provided a shred of evidence for different routes of taking up the candidate drugs by the parasite. In conclusion, the results of the previous work in vivo and current in vitro study recommend myrrh over garden cress as a complementary agent of albendazole.

The utility of alternative models in particulate matter air pollution toxicology

•

Countless unique particulate matter (PM) samples with limited or no toxicity information.

•

Alternative in vivo models offer greater throughput than traditional mammalian models.

•

Use of zebrafish, fruit flies, and nematodes in PM toxicology lacks systematic review.

•

Their utility in PM toxicity and mechanistic research and as screening tools is reviewed.

Exposure to particulate matter (PM) air pollution increases risk of adverse human health effects. As more attention is brought to bear on the problem of PM, traditional mammalian in vivo models struggle to keep up with the risk assessment challenges posed by the countless number of unique PM samples across air sheds with limited or no toxicity information. This review examines the utility of three higher throughput, alternative, in vivo animal models in PM toxicity research: Danio rerio (zebrafish), Caenorhabditis elegans (nematode), and Drosophila melanogaster (fruit fly). These model organisms vary in basic biology, ease of handling, methods of exposure to PM, number and types of available assays, and the degree to which they mirror human biology and responsiveness, among other differences. The use of these models in PM research dates back over a decade, with assessments of the toxicity of various PM sources including traffic-related combustion emissions, wildland fire smoke, and coal fly ash. This article reviews the use of these alternative model organisms in PM toxicity studies, their biology, the various assays developed, endpoints measured, their strengths and limitations, as well as their potential role in PM toxicity assessment and mechanistic research going forward.

Assessment of the effects of seasonality on the ecotoxicity induced by the particulate matter using the animal model Caenorhabditis elegans

The present work aimed to establish potential changes in the ecotoxicological effects on C. elegans induced by the exposure of coarse (PM₁₀) and fine (PM_2.5) particulate matter collected during dry and rainy periods. We also analyzed the probable influence on the change of a city's activities as the mega-events result in air quality. The element levels evaluation was performed on PM, on the solutions of exposure, and C. elegans after exposure. Biochemical essays were performed to evaluate damage to C. elegans. The results showed that infrastructure works increased the levels of pollutants, generating increases in the concentrations of PM_2.5 and PM₁₀. The biochemical results suggested effects mediated by different mechanisms, where PM_2.5 induced an increase in antioxidant capacity with activation of the defense system and lipoperoxidation. Results suggest that PM₁₀ reduces the antioxidant capacity and activates the glutathione S-transferase activity enzymatic action, but also induces lipoperoxidation in all groups of animals exposed to samples collected during the dry period of 2016. Individuals exposed to PM_2.5 in 2017 wet and dry periods and PM₁₀ in 2016 and 2017 dry periods shown a decrease in size compared to controls, while for fertility data, there was a decrease only in individuals exposed to PM_2.5 in the periods that the highest levels of PM concentration. We conclude that despite the positive issues linked to the hosting of mega-events, their infrastructure requirements can compromise air quality and bring damage related to lipoperoxidation and physiological changes in the life cycle of biological systems, such as what happened to C. elegans exposed to tested extracts. Also, rainy events reduced the presence of these pollutants, washing the atmosphere.

Maternal exposure to PM2.5 induces the testicular cell apoptosis in offspring triggered by the UPR-mediated JNK pathway

Contemporary exposure to PM_2.5 has been reported to disrupt spermatogenesis. However, the subsequent toxicological responses and the mechanisms of male reproductive damage in offspring induced by maternal exposure to PM_2.5 remain largely unknown. For the first time, this study aimed to explore the apoptotic response in spermatogenesis of male offspring following maternal exposure to PM_2.5 and its mechanisms. The C57BL/6 mice with vaginal plugs were randomly divided into four groups. Mice in the PM_2.5 groups were intratracheally exposed to PM_2.5 (4.8 mg/kg body weight, 43.2 mg/kg body weight) during pregnancy (every 3 days, six times in total). The mice in the membrane control group were treated similarly to the PM_2.5 groups, applying only PM_2.5 sampling membrane, while mice in the control group were kept untreated. The results showed that maternal exposure to PM_2.5 during pregnancy resulted in structural lesions of the testis, reduced numbers of primary spermatocytes and spermatids, decreased sperm count and quality, shortened diameter of seminiferous tubules, and reduced testosterone and ABP in the offspring testes. Furthermore, cell apoptosis was increased and protein expression of IRE-1/P-JNK/cleaved caspase-12/cleaved caspase-3 was activated. These findings suggested that maternal exposure to PM_2.5 may affect spermatogenesis by increasing apoptosis through activation of UPR-mediated JNK apoptotic pathway in offspring testicles and by reducing testosterone secretion.

Experimental study on the removal of PM2.5 using modified carbon steel collectors with hydrophilic properties in wet ESPs

Along with the increasingly stringent dust emission concentration standards for the thermal power plants and the challenge of market competition, wet electrostatic precipitators (ESPs) have been widely used as terminal equipment for the flue gas treatment. The wet ESPs pilot test platform using the modified carbon steel collectors with hydrophilic properties was established in this paper and the experimental research on PM_2.5 removal characteristics were carried out. The mechanism of the particles removal efficiency enhancement by water film on the surface of modified collectors was studied. The effect of gas temperature, residence time, working voltage, inlet concentration, and flushing water flowrate on the particles removal efficiency was investigated. The results indicated that the fibrous layer over the surface of the modified collectors could reduce the effect of the airflow recoil and the electromigration resistance of particles. The surface of the modified collectors could also maintain a uniform and stable water film with a lower amount of water consumption. The water film could restrain the back corona and the re-entrainment of dust. And the evaporation of water film increased the humidity of the flue gas, meanwhile, the particles charge capacity and electromigration velocity increased. Those all could improve the particles removal efficiency. The particles removal efficiency increased with the increase of the flue gas residence time and the applied voltage, but the particles removal efficiency improved less with the increase of the particles inlet concentration and flushing water flow rate after maintaining uniform and stable water film. The modified rigid collector provided high removal efficiency for particles with diameters of 0.04～0.48 μm under lower energy and water consumption.Implications: The wet electrostatic precipitators (ESPs) have been widely used as terminal equipment of the flue gas treatment to purify the flue gas deeply. The surface of the modified carbon steel collectors with hydrophilic properties could maintain a uniform and stable water film with a lower amount of water consumption. The evaporation of water film improved the particle charge capacity and electromigration velocity. The wet ESPs using the modified rigid collector exhibited significantly higher removal efficiency of particles than using the conventional rigid collector especially to the particles with diameter of 0.04～0.48 μm.

The aqueous extract of Fridericia chica grown in northern Colombia ameliorates toxicity induced by Tergitol on Caenorhabditis elegans

The aqueous extract of fallen leaves from Fridericia chica (Bonpl.) L.G. Lohmann is utilized as a remedy in communities at northern Colombia. Traditional uses include wound healing, gastrointestinal inflammation, leukemia and psoriasis, among others. The aims of this research were to evaluate the potential of the aqueous extract of fallen leaves of F. chica (AEFchica) to inhibit ethoxylated nonylphenol (Tergitol)-induced toxicity in Caenorhabditis elegans; and to identify its main components. The pharmacological properties of AEFchica was evaluated using a Tergitol-induced toxicity model in Caenorhabditis elegans. Lethality, locomotion, reproduction, and DAF-16 nuclear translocation were quantified. The chemical composition of AEFchica was carried out using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry. AEFchica induced very little lethality on C. elegans (5.6%) even at high concentrations (10,000 μg/mL). The extract had no effect on locomotion impairing induced by ethoxylated nonylphenol. However, AEFchica (1000 μg/mL) abrogated Tergitol-induced mortality, recovering up to 53.3% of the nematodes from lethality induced by 10 mM Tergitol. Similarly, it also blocked Tergitol-dependent reproduction inhibition (82.1% recovery), as well as DAF-16 nuclear translocation (>95%), suggesting a prominent role on oxidative stress control. The chemical analysis indicated the presence of a great variety of molecules with known antioxidant, metabolic and immune modulator properties, such as hydroxylated methoxy flavones, N-methyl-1-deoxynojirimycin, and rehmaionoside A. In short, the aqueous extract of F. chica protects C. elegans from the deleterious effects of Tergitol on lethality, reproduction and oxidative stress involving DAF-16-mediated pathway. This extract is a promising source of bioactive phytochemicals for multi-target pharmacological purposes.

Experimental study on the removal of fine particles using hole-slotted collectors in wet electrostatic precipitators

The fine particles are considered a significant environmental pollution problem. The wet electrostatic precipitators (ESPs) are now used most widely among the advanced fine particle removal technologies. The rigid glass fiber reinforced plastics (FRP) collectors modified with hole-slotted structures were used to enhance the water film distribution over their surfaces. This paper experimentally investigated the effects of the hole-slot patterns and the operating parameters on the particle removal performance in wet ESPs using the hole-slot-structured collector. The voltage-current characteristics and the energy consumption among the different pattern collectors were discussed. Besides, the effects of the water film on the particle number concentration classification and the effects of the applied voltage and the specific collecting electrode areas (SCA) on the relative collection efficiency (RCE) were investigated and discussed. The experiment results show that the corona current of three hole-slot structured FRP collectors was higher than that of the conventional rigid collectors (CRC) at the same voltage. Using the FRP collectors with circular holes and horizontal slots could decrease the energy consumption and using the FRP collectors with vertical slots increases the energy consumption compared with the CRC when the collection efficiency was lower than 92.5%. The water film could increase the collection efficiency of the fine particles and prevent the fine particles cross through the holes and the slots. The hole-slot-structured FRP collectors were appropriate for the working conditions of high SCA and long residence time. When the water film in the hole and slotted structures was incomplete, the fine particles could pass through the collector plate to form secondary back-mixing.Implications: The wet ESPs are used most widely among the advanced treatment technologies of the fine particles' removal. The rigid glass fiber reinforced plastics (FRP) collectors modified with hole-slotted structures were used to enhance the water film distribution over their surfaces. The hole-slot-structured FRP collectors were appropriate for the working conditions of high SCA and long residence time. When the water film in the hole and slotted structures was incomplete, the fine particles could pass through the collector plate to form secondary back-mixing.

Assessment of the effects of atmospheric pollutants using the animal model Caenorhabditis elegans

Air pollution is recognized as the world's largest environmental health risk. In this work we evaluated in vivo the effects of three relevant components of atmospheric dusts (brake dust, wood pellet ash and Saharan dust) employing the animal model Caenorhabditis elegans. Main endpoints of C. elegans such as life span, brood size and oxidative stress were addressed by exposing the nematodes to different dust concentrations. Brake dust and pellet ash affected the life span and increased significantly the oxidative stress of exposed nematodes, while Saharan dust showed no effects. Water soluble and insoluble fractions of these dusts were used to investigate the impact of the single fraction on C. elegans. The two fractions of brake dust and pellet ash exerted different effects on C. elegans endpoints in terms of life span and oxidative stress response. These fractions acted in different ways on the worm susceptibility to infection of two human pathogens (Staphylococcus aureus and Pseudomonas aeruginosa) affecting the sek-1 gene expression. In conclusion, our study showed that C. elegans is a valuable tool to investigate in vivo possible effects of atmospheric dusts.

Public health effect and its economics loss of PM2.5 pollution from coal consumption in China

China's energy structure is based on coal resource and it accounts for main proportion in the primary energy consumption. Coal consumption produces PM_2.5 pollution, which seriously affects public health. Considering that there are few studies on the effect PM_2.5 pollution produced by coal consumption, this paper uses the Poisson Regression model to estimate the impacts on public health and the economic loss of PM_2.5 pollution produced by coal consumption using the data in 2015. Based on these results, the paper also predicts the impacts on public health effect and its economic loss caused by PM_2.5 pollution from coal consumption under the baseline scenario and total coal consumption control scenario in 2020 and 2030. Finally, based on the research conclusions, suggestions are proposed to reduce the public health economic loss from PM_2.5 pollution caused by coal consumption.

Polystyrene microplastics (PS-MPs) toxicity induced oxidative stress and intestinal injury in nematode Caenorhabditis elegans

To understand the toxicity and mechanism of polystyrene microplastics (PS-MPs) exposure, Caenorhabditis elegans (C. elegans) was exposed to various concentrations (0, 0.1, 1, 10, and 100 μg/L) of PS-MPs, and the levels physiological, biochemical, and molecular parameters were measured as endpoints. Subacute exposure to 1-100 μg/L of PS-MPs resulted in adverse physiological effects in C. elegans, and PS-MPs were ingested and accumulated in the intestine of C. elegans. Exposure to 100 μg/L of PS-MPs significantly increased reactive oxygen species (ROS) production, lipofuscin accumulation, and the expression oxidative stress-related genes, which suggests that PS-MPs exposure induced oxidative stress by ROS. In addition, exposure to 100 μg/L of PS-MPs caused a hyperpermeable state of the intestinal barrier and altered the expression of genes related to intestinal development, which indicates intestinal damage in C. elegans. According to Pearson correlation analyses, oxidative stress and intestinal damage were significantly correlated with adverse effects of PS-MPs in C. elegans. Therefore, it was speculated that the toxicity induced by PS-MPs resulted from the combination of oxidative stress and intestinal injury.

Evidence for Fossil Fuel PM1 Accumulation in Marine Biota

When fine particulates such as those with a diameter of approximately 1 μm (particulate matter, PM₁) are released from fossil fuel combustion into the air, they warm the atmosphere and contribute to millions of premature deaths in humans each year. Considerable quantities of PM₁ eventually enter the oceans as suspended particulates, yet subsequent removal mechanisms are poorly understood. In fact, the presence of PM₁ in marine biota has never been reported. Since sea anemones are opportunistic suspension feeders, they are anticipated to incorporate and accumulate PM₁ in their bodies. By histological examination, PM₁ was detected in 21 of the 22 sea anemones collected from Taiwan and Southeast China, with a depth of intertidal zone to 1000 m. PM₁, if present, was always detected in endodermal layers and had the same dominant color (i.e., black, brown, or green) in different species from the same site. The bioaccumulation factor of PM₁ in sea anemones was approximately 5-7 orders of magnitude. Based on radioisotope ¹⁴C results, the contribution of fossil fuel source PM₁ was 8-24%. Regardless of PM₁'s color, S and Fe were commonly detected by scanning electron microscopy and energy-dispersive spectrometry (SEM-EDS), suggesting anthropogenic sources. Furthermore, a maternal transfer of materials was suggested based on the existence of PM₁ in sea anemone eggs and in brooding and released juveniles. The significance of PM₁ accumulation by biota in aquatic ecosystems and the potential risk to living organisms via food webs warrant further investigation.

Microplastic (1 and 5 μm) exposure disturbs lifespan and intestine function in the nematode Caenorhabditis elegans

As an emerging environmental pollutant, microplastics (MPs) are increasingly viewed as a serious health concern to terrestrial and aquatic ecosystems. However, previous toxicological studies examining MPs on freshwater and terrestrial organisms provide contradictory results, possibly due to few investigations at environmentally relevant concentrations. Here, the nematode Caenorhabditis elegans (C. elegans), a model organisms with both aquatic and terrestrial free-living forms, was employed to investigate the effects of 1 and 5 μm MPs (10⁷-10¹⁰ particles/m²) on the intake, lifespan, defecation rhythm, defecation-related neurons and transcriptional expression of related genes (skn-1, mkk-4, pmk-1, cpr-1 and itr-1). We demonstrated that the percentage of MP-contaminated nematodes increased with increasing exposure concentrations and duration. The lifespan of nematodes in the lower concentration exposure groups (2.4 × 10⁷ and 2.4 × 10⁸ particles/m²) decreased more prominently than that of higher concentration groups (2.4 × 10⁹ and 2.4 × 10¹⁰ particles/m²) after a 72-h exposure period. Concomitantly, expression of the skn-1 gene, involved in detoxification and lifespan regulation, was significantly altered at lower MP concentrations. Physiologically, the defecation rhythm after a 72-h exposure period was most strongly affected by 1 μm MPs at 2.4 × 10⁸ particles/m². The significant up-regulation of related genes by 1 μm MPs appears responsible for the shortened defecation interval. Results of this study identified a potential toxicity threat to C. elegans from exposure to MPs at environmentally relevant concentrations and provide novel evidence for MP risks to freshwater and terrestrial organisms. Capsule. After exposure to 1 and 5 μm MPs (10⁷-10¹⁰ particles/m²), the lifespan of C. elegans decreased more rapidly at lower concentrations.

The mechanisms of PM2.5 and its main components penetrate into HUVEC cells and effects on cell organelles

Atmospheric particulate matter (PM_2.5) is associated with the morbidity and mortality of cardiovascular diseases. However, whether PM_2.5 penetrates into the cells and the potential mechanisms are unknown. Hence, the study firstly indicated that PM_2.5 could penetrate into the HUVEC cells, and phagocytosis, micropinocytosis, caveolin as well as clathrin mediated the internalization of PM_2.5 into HUVEC cells. Particularly, the components of PM_2.5-Metal, PAHs and WSC could enter into HUVEC cells mainly via the micropinocytosis, clathrin and caveolin mediated endocytosis, respectively. The current data of environmental assessments indicated that PM_2.5-Metal were extremely harmful to the ecological environment and human health. Moreover, accompanying with mitochondrial fusion gene Mfn1 was increased and fission genes Opa1 and Drp1 were decreased, and the lysosome related genes LAMP2 and LAMP3 were decreased, the phenomenon that the morphology of mitochondrial and lysosome injured was observed in HUVEC cells treated with PM_2.5 and/or PM_2.5-Metal. These data suggest that PM_2.5 and its main components depend on different endocytosis penetrate into HUVEC cells and cause the mitochondrial and lysosomal damages. Thereby, our study provides the potential mechanism of haze particles penetration into HUVEC cells and damage to organelles.

Toxicity of nonylphenol and nonylphenol ethoxylate on Caenorhabditis elegans

Among the most used chemicals in the world are nonionic surfactants. One of these environmental pollutants is nonylphenol ethoxylate (NP-9), also known as Tergitol, and its degradation product, nonylphenol (NP). The objective of this work was to determine the toxicity of NP and NP-9 in Caenorhabditis elegans. Wild-type L4 larvae were exposed to different concentrations of the surfactants to measure functional endpoints. Mutant strains were employed to promote the activation of toxicity signaling pathways related to mtl-2, gst-1, gpx-4, gpx-6, sod-4, hsp-70 and hsp-4. Additionally, stress response was also assessed using a daf-16::GFP transgenic strain. The lethality was concentration dependent, with 24-h LC₅₀ of 122 μM and 3215 μM for NP and NP-9, respectively. Both compounds inhibited nematode growth, although NP was more potent; and at non-lethal concentrations, nematode locomotion was reduced. The increase in the expression of tested genes was significant at 10 μM for NP-9 and 0.001 μM for NP, implying a likely role for the activation of oxidative and cellular stress, as well as metabolism pathways. With the exception of glutathione peroxidase, which has a bimodal concentration-response curve for NP, typical of endocrine disruption, the other curves for this xenobiotic in the strains evaluated were almost flat for most concentrations, until reaching 50-100 μM, where the effect peaked. NP and NP-9 induced the activation and nuclear translocation of DAF-16, suggesting that transcription of stress-response genes may be mediated by the insulin/IGF-1 signaling pathway. In contrast, NP-9 induced a concentration-dependent response for the sod-4 and hsp-4 mutants, with greater fluorescence induction than NP at similar levels. In short, NP and NP-9 affect the physiology of C. elegans and modulate gene expression related to ROS production, cellular stress and metabolism of xenobiotics.

Transgenerational effects of diesel particulate matter on Caenorhabditis elegans through maternal and multigenerational exposure

Diesel particulate matter (DPM) is a dominant contaminant in fine particulate matters (PM_2.5) and has been proved to induce serious harmful effects to human beings, including lung cancer, allergic, and chronic bronchitis. However, little attention has been paid to understand the transgenerational effects of DPM. In the present study, we focused on the transgenerational effects of DPM in the model organism Caenorhabditis elegans (C. elegans) exposed in either maternal generation (F0) or consecutive generations (F0-F5). In maternal exposure manner, 0.1 and 1.0 µg/mL DPM significantly increased the germ cell apoptosis at F0 generation, while the number of apoptotic germ cells at F1-F5 generation were gradually recovered back to control level. The brood size were significantly reduced by DPM at F2 generation and recovered to control level at F3-F5 generations. In continuous exposure manner, although 0.1 and 1.0 µg/mL DPM induced significant germ cell apoptosis in F0 generation, there was no difference between F0 and other generations. Continuous exposure to DPM at 0.1 and 1.0 µg/mL impaired the brood size in F2 to F5 generations. Using a series of loss-of-function mutant strains, we found that cep-1 (w40), hus-1 (op241), and mitogen-activated protein kinase (MAPK) related signaling pathway genes were involved in DPM-induced apoptosis. Our results clearly demonstrated that the adverse effects of DPM could be passed on through long-term multigenerational exposure and DNA damage checkpoint genes and MAPK signal pathway played an essential role in response to DPM induced development and reproduction toxicity.

Metal contaminated soil leachates from an art glass factory elicit stress response, alter fatty acid metabolism and reduce lifespan in Caenorhabditis elegans

The present study evaluated the toxicity of metal contamination in soils from an art glass factory in Småland Sweden using a Caenorhabditis elegans nematode model. The aim of the study was to chemically analyze the soil samples and study the biological effects of water-soluble leachates on the nematodes using different physiological endpoints. The total metal content showed that As, Cd and Pb were at levels above the guideline values for soils in areas around the factory. Less than 10% of the total metal content in the soil was found in the water-soluble leachates, however, Al, As, Fe and Pb remained higher than the guideline values for safe drinking water. Exposure of C. elegans to the water-soluble leachates, at both post-hatching larvae stage (L1-young adult) for 48 h and at the young adult stage (L4) for 6 h, showed significant gene alteration. Although the nematodes did not exhibit acute lethality, lifespan was significantly reduced upon exposure. C. elegans also showed altered gene expression associated with stress response and fat metabolism, as well as enhanced accumulation of body fat. The study highlighted the significance of assessing environmental samples using a combination of gene expression analysis, fatty acid metabolism and lifespan for providing valuable insight into the negative impact of metals. The altered fat metabolism and reduced lifespan on exposure to soil leachates motivates further studies to explore the mechanism of the toxicity associated with the metals present in the environment.

Neurotoxicity of nonylphenol exposure on Caenorhabditis elegans induced by reactive oxidative species and disturbance synthesis of serotonin

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.

Assessing the influence of the genetically modified factor on mixture toxicological interactions in Caenorhabditis elegans: Comparison between wild type and a SOD type

How to evaluate the ecological risk of transgenic technology is a focus of scientists because of the safety concerns raised by genetically modified (GM) organisms. Nevertheless, most studies are based on individual chemicals and always analyze the GM organism as a type of toxicant. In this study, we changed the approach and used GM organisms as the test objects with normal chemical exposure. Three types of chemicals (two substituted phenols, 4-chlorophenol and 4-nitrophenol; two ionic liquids, 1-butylpyridinium chloride and 1-butylpyridinium bromide; two pesticides, dichlorvos and glyphosate) were used to construct a six-component mixture system. The lethality to wild-type (N2) and sod-3::GFP (SOD-3) Caenorhabditis elegans was determined when they were exposed to the same mixture system after 12 and 24 h. The results showed that the pEC50 values of all of the single chemicals on SOD-3 were greater than those on N2 at 24 h. The toxicities of the single chemicals and nine mixture rays on the two strains increased with time. Notably, we discovered a significant difference between the two strains; time-dependent synergism occurred in mixtures on N2, but time-dependent antagonism occurred in mixtures on SOD-3. Finally, the strength of the synergism or antagonism turned to additive action on the two strains as the exposure time increased. These findings illustrated that the GM factor of the nematode influenced the mixture toxicological interaction at some exposure times. Compared with N2, SOD-3 were more sensitive to stress or toxic reactions. Therefore, the influence of the GM factor on mixture toxicological interactions in environmental risk assessment must be considered.

Chronic exposure to triadimenol at environmentally relevant concentration adversely affects aging biomarkers in Caenorhabditis elegans associated with insulin/IGF-1 signaling pathway

Triadimenol, an agricultural fungicide, is an emerging environmental concern due to its wide usage, detection in the environment, and its chemical persistency. Triadimenol has been found to disrupt endocrine signaling and alter function of several transcription factors, yet its age-related toxicity effects remain unclear. This study used Caenorhabditis elegans as an in vivo model organism to elucidate the age-related effects of triadimenol and its underlying mechanisms. The results showed that chronic exposure to triadimenol at environmentally relevant concentrations (3, 30, and 300 μg/L) adversely affected several toxicity endpoints including growth, total brood size, and locomotive behaviors. In addition, triadimenol (300 μg/L) significantly reduced the mean lifespan of wild-type N2 C. elegans from 17.9 to 16 days. Chronic exposure to triadimenol (300 μg/L) also significantly affected age-related behavioral changes, with a decreased pharyngeal pumping rate and an increased defecation cycle. Moreover, an increased accumulation of aging biomarkers including lipofuscin, lipid peroxidation, and reactive oxygen species (H₂O₂ and O₂^-) level upon chronic triadimenol exposure was observed in aged worms. Furthermore, chronic triadimenol exposure increased the transcriptional factor DAF-16 nuclear localization. Finally, mutation of daf-2, age-1, pdk-1, akt-1, or akt-2 restored the accumulation of lipofuscin in aged worms upon chronic triadimenol exposure, while mutation of daf-16 led to more enhanced lipofuscin accumulation. Therefore, the insulin/IGF-1 signaling pathway may serve as an important molecular basis for triadimenol induced aging declines in C. elegans.

Potential harmful elements in coal dust and human health risk assessment near the mining areas in Cherat, Pakistan

This study was aimed to investigate the potential harmful element (PHE) concentrations in coal dust and evaluate the human risk assessment and health effects near coal mining areas. For this purpose, dust samples were collected near various coal mines in Cherat, Pakistan, and analyzed for the PHE concentrations. Determined PHE concentrations were evaluated for the health risk assessment. Results revealed that ingestion was the major pathway as compared to others for PHE exposure. Individual chronic daily intake (CDI) of PHEs was higher than their respective permissible exposure limits set for oral exposure routes by the Agency for Toxic Substances and Disease Registry (ATSDR). Chronic risk or health index (HI) values were observed < 1 for all PHEs and in the order of Pb > Cr > Cd > Ni > Cu > Co > Zn. Higher HI values of Pb, Cr, and Cd could attribute to various chronic health problems as observed during the medical examination survey of this study. Cancer risk (CR) values for this study were observed within the US Environmental Protection Agency (EPA) limits. However, if current practices continued, the PHEs will cross these limits in a near future. Therefore, this study strongly recommends the provision of safety measures, rules, and regulation to avoid health hazards in the future.

Long-term exposure to thiolated graphene oxide in the range of μg/L induces toxicity in nematode Caenorhabditis elegans

The in vivo toxicity and translocation of thiolated graphene oxide (GO-SH) are still largely unclear. We hypothesized that long-term exposure to GO-SH may cause the adverse effects on environmental organisms. We here employed in vivo assay system of Caenorhabditis elegans to investigate the possible toxicity and translocation of GO-SH after long-term exposure. In wild-type nematodes, we observed that prolonged exposure to GO-SH at concentrations>100μg/L resulted in the toxicity on functions of both primary targeted organs such as the intestine and secondary targeted organs such as the neurons and the reproductive organs. The severe accumulation of GO-SH was further detected in the body of wild-type nematodes. The translocation of GO-SH into secondary targeted organs such as reproductive organs through intestinal barrier might be associated with the enhancement in intestinal permeability in GO-SH exposed wild-type nematodes. Prolonged exposure to GO-SH (100μg/L) decreased the expression of gas-1 encoding a subunit of mitochondrial complex I, and mutation of gas-1 caused the formation of GO-SH toxicity at concentration>10μg/L and more severe accumulation of GO-SH in the body of animals. Therefore, our results confirm the possibility for prolonged exposure to GO-SH in inducing adverse effects on nematodes. Our data highlight the potential adverse effects of GO-SH in the range of μg/L on environmental organisms after long-term exposure.

Toxicity profile of organic extracts from Magdalena River sediments

The Magdalena River, the main river of Colombia, receives contaminated effluents from different anthropogenic activities along its path. However, the Magdalena River is used as drinking water source for approximately 30 million inhabitants, as well as a major source of fish for human consumption. Only a few studies have been conducted to evaluate the environmental and toxicological quality of the Magdalena River. To evaluate sediment toxicity, wild-type and GFP transgenic Caenorhabditis elegans were exposed to methanolic extracts, and effects on lethality, locomotion, growth, and gene expression were determined based on fluorescence spectroscopy. These biological and biochemical parameters were correlated with measured pollutant concentrations (PAHs and trace elements), identifying patterns of toxicity along the course of the river. Effects on lethality, growth, and locomotion were observed in areas influenced by industrial, gold mining, and petrochemical activities. Changes in gene expression were evident for cyp-34A9, especially in the sampling site located near an oil refinery, and at the seaport, in Barranquilla City. Body bend movements were moderately correlated with Cr and As concentrations. The expression of mtl-1, mtl-2, hsp-6, and hsp-70 were significantly associated with Pb/U, Pb, Sr, and As/Sr/Pb/U, respectively. Interestingly, toxicity of methanolic as well as aqueous extracts were more prone to be dependent on Cd, Zn, and Th. In general, ecological risk assessment showed sediments display low environmental impact in terms of evaluated metals and PAHs. Different types of waste disposal on the Magdalena River, as a result of mining, domestic, agricultural, and industrial activities, incorporate toxic pollutants in sediments, which are capable of generating a toxic response in C. elegans.

PM2.5 particulates and metallic elements (Ni, Cu, Zn, Cd and Pb) study in a mixed area of summer season in Shalu, Taiwan

PM_2.5 has become an important environmental issue in Taiwan during the past few years. Moreover, electricity increased significantly during the summertime and TTPP generated by coal burning base is the main electricity provider in central Taiwan. Therefore, summer season has become the main research target in this study. The ambient air concentrations of particulate matter PM_2.5 and PM₁₀ collected by using VAPS at a mixed characteristic sampling site were studied in central Taiwan. The results indicated that the average daytime PM_2.5 and PM₁₀ particulate concentrations were occurred in May and they were 44.75 and 57.77 µg/m³ in this study. The results also indicated that the average nighttime PM_2.5 and PM₁₀ particulate concentrations were occurred in June and they were 38.19 and 45.79 µg/m³ in this study. The average PM_2.5/PM₁₀ ratios were 0.7 for daytime, nighttime and 24-h sampling periods in the summer for this study. This value was ranked as the lowest ratios when compared to the other seasons in previous study. Noteworthy, the results further indicated that the metallic element Pb has the mean highest concentrations for 24-h, daytime and nighttime sampling periods when compared to those of the other metallic elements (Ni, Cu, Zn and Cd). The average mean highest metallic Pb concentrations in PM10 were 110.7, 203.0 and 207.2 ng/m³ for 24-h, daytime and nighttime sampling periods in this study. And there were 59.53, 105.2 and 106.6 ng/m³ for Pb in PM2.5 for 24-h, daytime and nighttime sampling periods, respectively. Moreover, the results further indicated that mean metallic element Pb concentrations on PM_2.5 and PM₁₀ were all higher than those of the other elements for 24 h, day and nighttime.

Coal combustion related fine particulate matter (PM2.5) induces toxicity in Caenorhabditis elegans by dysregulating microRNA expression

We employed an in vivo assay system of Caenorhabditis elegans to determine if and which microRNAs (miRNAs) were dysregulated upon exposure to coal combustion related fine particulate matter (PM2.5) by profiling the miRNAs using SOLiD sequencing. From this, expression of 25 miRNAs was discovered to become dysregulated by exposure to PM2.5. Using the corresponding C. elegans deletion mutants, 5 miRNAs (mir-231, mir-232, mir-230, mir-251 and mir-35) were found to be involved in the control of PM2.5 toxicity. Furthermore, mutation of mir-231 or mir-232 induced a resistance to PM2.5 toxicity, whereas mutation of mir-230, mir-251, or mir-35 induced a susceptibility to PM2.5 toxicity. SMK-1, an ortholog of the mammalian SMEK protein, was identified as a molecular target for mir-231 in the regulation of PM2.5 toxicity. In addition, the genes of sod-3, sod-4 and ctl-3, which are necessary for protection against oxidative stress, were determined to be important downstream targets of smk-1 in the regulation of PM2.5 toxicity. The triggering of this mir-231-SMK-1-SOD-3/SOD-4/CTL-3 signaling pathway may be a critical molecular basis for the role of oxidative stress in the induction of coal combustion related PM2.5 toxicity.

Exposure and health risk assessment of PM2.5-bound trace metals during winter in university campus in Northeast China

In order to better understand the risk to students' health caused by pollution derived from fine particulate matter with an aerodynamic diameter <2.5mm (PM_2.5), this study collected 189 samples in one outdoor and four different functional indoor environments of a research center in a university campus. Trace metals (TMs) bound to PM_2.5 in outdoor and indoor environments were measured using X-ray fluorescence spectrometry. The TMs measured were: As, Co, Cd, Cr, Ni, Cu, Zn, Mn, Hg, and Pb. The measurements of PM_2.5-bound TMs before and during the 2015 Spring Festival held in Northeast China were compared. Results showed that pollution due to PM_2.5-bound TMs in outdoor and indoor environments was higher before than during the Spring Festival. Cu (in three indoor environments) and Zn (in an outdoor environment) showed the highest concentrations among the ten TMs that were measured. Hg showed the lowest concentrations in all the environments analyzed. The concentrations of PM_2.5-bound TMs declined among four indoor environments in the following order: the atrium, the students' office (sampled just nine days before the Spring Festival), the laboratory, and an empty room. The potential carcinogenic and non-carcinogenic health risks derived from PM_2.5-bound TMs were within safe limits for graduate and undergraduate students, according to the standards established by the United States Environmental Protection Agency (USEPA).

p38 MAPK-SKN-1/Nrf signaling cascade is required for intestinal barrier against graphene oxide toxicity in Caenorhabditis elegans

Biological barrier plays a crucial role for organisms against the possible toxicity from engineered nanomaterials (ENMs). Graphene oxide (GO) has been proven to cause potential toxicity on organisms. However, the molecular mechanisms for intestinal barrier of animals against GO toxicity are largely unclear. Using in vivo assay system of Caenorhabditis elegans, we found that mutation of genes encoding core p38 mitogen-activated protein kinase (MAPK) signaling pathway caused susceptible property to GO toxicity and enhanced translocation of GO into the body of nematodes. Genetic assays indicated that SKN-1/Nrf functioned downstream of p38 MAPK signaling pathway to regulate GO toxicity and translocation. Transcription factor of SKN-1 could regulate GO toxicity and translocation at least through function of its targeted gene of gst-4 encoding one of phase II detoxification proteins. Moreover, intestine-specific RNA interference (RNAi) assay demonstrated that the p38 MAPK-SKN-1/Nrf signaling cascade could function in intestine to regulate GO toxicity and intestinal permeability in GO exposed nematodes. Therefore, p38 MAPK-SKN-1/Nrf signaling cascade may act as an important molecular basis for intestinal barrier against GO toxicity in organisms. Exposure to GO induced significantly increased expression of genes encoding p38 MAPK-SKN-1/Nrf signaling cascade, which further implies that the identified p38 MAPK-SKN-1/Nrf signaling cascade may encode a protection mechanism for nematodes in intestine to be against GO toxicity.

Heavy metals bound to fine particulate matter from northern China induce season-dependent health risks: A study based on myocardial toxicity

Substantial epidemiological evidence has consistently reported that fine particulate matter (PM2.5) is associated with an increased risk of cardiovascular outcomes. PM2.5 is a complex mixture of extremely small particles and liquid droplets composed of multiple components, and there has been high interest in identifying the specific health-relevant physical and/or chemical toxic constituents of PM2.5. In the present study, we analyzed 8 heavy metals (Cr, Ni, Cu, Cd, Pb, Zn, Mn and Co) in the PM2.5 collected during four different seasons in Taiyuan, a typical coal-burning city in northern China. Our results indicated that total concentrations of the 8 heavy metals differed among the seasons. Zn and Pb, which are primarily derived from the anthropogenic source, coal burning, were the dominant elements, and high concentrations of these two elements were observed during the spring and winter. To clarify whether these heavy metals in the locally collected PM2.5 were associated with health effects, we conducted health risk assessments using validated methods. Interestingly, Pb was responsible for greater potential health risks to children. Because cardiovascular disease (CVD) is a main contributor to the mortality associated with PM2.5 exposure, we performed experimental assays to evaluate the myocardial toxicity. Our in vitro experiments showed that the heavy metal-containing PM2.5 induced season-dependent apoptosis in rat H9C2 cells through a reactive oxygen species (ROS)-mediated inflammatory response. Our findings suggested that heavy metals bound to PM2.5 produced by coal burning play an important role in myocardial toxicity and contribute to season-dependent health risks.

Metallothioneins act downstream of insulin signaling to regulate toxicity of outdoor fine particulate matter (PM2.5) during Spring Festival in Beijing in nematode Caenorhabditis elegans

In this study, we performed the toxicological assessment of outdoor PM2.5 collected from Beijing during Spring Festival using the in vivo assay system of Caenorhabditis elegans. Acute exposure to outdoor PM2.5 at a concentration of 10 mg L-1 and prolonged exposure to outdoor PM2.5 at concentrations of 0.1-10 mg L-1 decreased locomotion behavior and caused significant induction of intestinal ROS production. Meanwhile, outdoor PM2.5 exposure induced significant expression of gene (mtl-1 and mtl-2) encoded metallothioneins in the intestine. Mutation of the mtl-1 or mtl-2 gene resulted in a susceptible property of nematodes to outdoor PM2.5 toxicity. Genetic assays suggested that mtl-1 and mtl-2 genes acted downstream of the daf-16 gene encoding a FOXO transcriptional factor and daf-2 gene encoding an insulin receptor in the insulin signaling pathway to regulate outdoor PM2.5 toxicity. DAF-2 further acted upstream of DAF-16 and suppressed the function of DAF-16 to regulate outdoor PM2.5 toxicity. Therefore, we identified a signaling cascade of DAF-2-DAF-16-MTL-1/2 in the control of outdoor PM2.5 toxicity in nematodes. Our study provides an important molecular basis for the potential toxicity of outdoor PM2.5 during Spring Festival in Beijing in nematodes. Especially, our study will highlight the potential adverse effects of outdoor PM2.5 during Spring Festival on environmental organisms.

Pollution by metals and toxicity assessment using Caenorhabditis elegans in sediments from the Magdalena River, Colombia

The Magdalena River is the most important river in Colombia, supplying over 70% of the population of fish and drinking water, and it also is the main river transportation way of the country. It receives effluents from multiple sources along its course such as contaminant agricultural and industrial discharges. To evaluate the toxicity profile of Magdalena River sediments through endpoints such as survival, locomotion, and growth, wild type strains of Caenorhabditis elegans were exposed to aqueous extracts of the sediments. To identify changes in gene expression, GFP transgenic strains were used as reporter genes. Physiological and biochemical data were correlated with metal concentration in the sediments, identifying patterns of toxicity along the course of the river. Levels of some metals such as Cd, Cu, and Ni were above TEC and PEC limits. Effects in survival, growth, and locomotion were observed in most of the samples, and changes in gene expression were evident in the genes mtl-2, sod-4, and gst-1 using fluorescence expression. Cadmium and lead were the metals which were primarily associated with sediment toxicity, and the sampling sites with the highest increased expression of stress response genes were Barrancabermeja and Girardot. However, the diverse nature of toxic profiles observed in C. elegans in the study area showed the pervasiveness of different types of discharges throughout the river system.

Biological effects, translocation, and metabolism of quantum dots in the nematode Caenorhabditis elegans

Quantum dots (QDs), semiconductor nanomaterials with tiny light-emitting particles, act as important alternatives to conventional fluorescent dyes for biomedical imaging. With the increased tendency towards QD applications, concerns about the likelihood of adverse health impacts from exposure to QDs have also received attention. The nematode Caenorhabditis elegans is an important non-mammalian alternative model for the toxicological study of environmental toxicants including engineered nanomaterials. In this review, we summarize recent progress on the biological effects, translocation, and metabolism of QDs in the in vivo assay system of C. elegans. Moreover, certain perspectives or suggestions are further raised for the future toxicological study of QDs in nematodes.

Intestinal Insulin Signaling Encodes Two Different Molecular Mechanisms for the Shortened Longevity Induced by Graphene Oxide in Caenorhabditis elegans

Graphene oxide (GO) has been shown to cause multiple toxicities in various organisms. However, the underlying molecular mechanisms for GO-induced shortened longevity are still unclear. We employed Caenorhabditis elegans to investigate the possible involvement of insulin signaling pathway in the control of GO toxicity and its underlying molecular mechanisms. Mutation of daf-2, age-1, akt-1, or akt-2 gene induced a resistant property of nematodes to GO toxicity, while mutation of daf-16 gene led to a susceptible property of nematodes to GO toxicity, suggesting that GO may dysregulate the functions of DAF-2/IGF-1 receptor, AGE-1, AKT-1 and AKT-2-mediated kinase cascade, and DAF-16/FOXO transcription factor. Genetic interaction analysis suggested the involvement of signaling cascade of DAF-2-AGE-1-AKT-1/2-DAF-16 in the control of GO toxicity on longevity. Moreover, intestinal RNA interference (RNAi) analysis demonstrated that GO reduced longevity by affecting the functions of signaling cascade of DAF-2-AGE-1-AKT-1/2-DAF-16 in the intestine. DAF-16 could also regulate GO toxicity on longevity by functioning upstream of SOD-3, which encodes an antioxidation system that prevents the accumulation of oxidative stress. Therefore, intestinal insulin signaling may encode two different molecular mechanisms responsible for the GO toxicity in inducing the shortened longevity. Our results highlight the key role of insulin signaling pathway in the control of GO toxicity in organisms.

Contribution of heavy metals to toxicity of coal combustion related fine particulate matter (PM2.5) in Caenorhabditis elegans with wild-type or susceptible genetic background

Contribution of chemical components in coal combustion related fine particulate matter (PM2.5) to its toxicity is largely unclear. We focused on heavy metals in PM2.5 to investigate their contribution to toxicity formation in Caenorhabditis elegans. Among 8 heavy metals examined (Fe, Zn, Pb, As, Cd, Cr, Cu, and Ni), Pb, Cr, and Cu potentially contributed to PM2.5 toxicity in wild-type nematodes. Combinational exposure to any two of these three heavy metals caused higher toxicity than exposure to Pb, Cr, or Cu alone. Toxicity from the combinational exposure to Pb, Cr, and Cu at the examined concentrations was higher than exposure to PM2.5 (100 mg/L). Moreover, mutation of sod-2 or sod-3 gene encoding Mn-SOD increased susceptibility in nematodes exposed to Fe, Zn, or Ni, although Fe, Zn, or Ni at the examined concentration did not lead to toxicity in wild-type nematodes. Our results highlight the potential contribution of heavy metals to PM2.5 toxicity in environmental organisms.

ACS-22, a protein homologous to mammalian fatty acid transport protein 4, is essential for the control of the toxicity and translocation of multi-walled carbon nanotubes in Caenorhabditis elegans

ACS-22 plays an essential role in regulating toxicity and translocation of MWCNTs.