Toxicological Responses Research Articles

Combined effects of cadmium and sulfamethoxazole on Eisenia fetida: Insights into accumulation, subcellular partitioning, biomarkers and toxicological responses

Cadmium (Cd) and sulfamethoxazole (SMX) frequently coexist in farmlands, yet their synergistic toxicological impacts on terrestrial invertebrates remain unexplored. In this study, earthworms were exposed to artificial soils percolated with Cd (5 mg/kg), SMX (5 mg/kg) or combination of them for 7 days, followed by a 12-day elimination phase in uncontaminated soil. The uptake of Cd and SMX by the earthworms, along with their subcellular distribution, was meticulously analyzed. Additionally, a suite of biomarkers—including superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and weight loss—were evaluated to assess the health status of the earthworms and the toxicological effects of the Cd and SMX mixture. Notably, the cotreatment with Cd and SMX resulted in a significantly higher weight loss in Eisenia fetida (41.25 %) compared to exposure to Cd alone (26.84 %). Moreover, the cotreatment group exhibited substantially higher concentrations of Cd in the total internal body, fraction C (cytosol), and fraction E (tissue fragments and cell membranes) in Eisenia fetida compared to Cd alone counterparts. The combined exposure also significantly elevated the SMX levels in the total body and fraction C compared with the SMX-only treated earthworms. Additionally, Eisenia fetida subjected to the combined treatment showed markedly increased activities of SOD, CAT, and MDA compared to those treated with Cd alone. The effect addition indices (EAIs), ranging from 1.00 to 2.23, unequivocally demonstrated a synergistic effect of the combined treatments. Interestingly, relocating the earthworms to clean soil did not mitigate the observed adverse effects. These findings underscore the increased risk posed by the Cd-SMX complex to terrestrial invertebrates in agricultural areas.

Size- and Shape-Dependent Interactions of Lipid-Coated Silver Nanoparticles: An Improved Mechanistic Understanding through Model Cell Membranes and In Vivo Toxicity.

The widespread use of silver nanoparticles (AgNPs) in various applications and industries has brought to light the need for understanding the complex relationship between the physicochemical properties (shape, size, charge, and surface chemistry) of AgNPs that affect their ability to enter cells and cause toxicity. To evaluate their toxicological outcomes, this study systematically analyzed a series of homogeneous hybrid lipid-coated AgNPs spanning sizes from 5 to 100 nm with diverse shapes (spheres, triangles, and cubes). The hybrid lipid membrane comprises hydrogenated phosphatidylcholine (HPC), sodium oleate (SOA), and hexanethiol (HT), which shield the AgNP surface from surface oxidation and toxic Ag+ ion release to minimize its contribution to toxicity. To reduce any significant effects by surface chemistry, the HPC, SOA, and HT membrane composition ratio was kept constant, and the AgNPs were assessed using embryonic zebrafish (Danio rerio). While a direct comparison cannot be drawn due to the lack of complementary sizes below 40 nm for triangular plates and cubes due to synthetic challenges, significant mortality was observed for spherical AgNPs (AgNSs) of 5, 20, 40, and 60 nm at 120 h postfertilization at concentrations ≥6 mg Ag/L. In contrast, the 10, 80, and 100 nm AgNSs, 40, 70, and 100 nm triangular plate AgNPs (AgNPLs), and 55, 75, and 100 nm cubic AgNPs (AgNCs) showed no significant mortality at 5 days postfertilization following exposure to AgNPs at concentrations up to 12 mg Ag/L. With constant surface chemistry on the AgNPs, size is the dominant factor driving toxicological responses, with smaller nanoparticles (5 to 60 nm) being the most toxic. Larger AgNSs, AgNCs, and AgNPLs from 75 to 100 nm do not show any evidence of toxicity. However, when closely examining sizes between 40 and 60 nm for AgNSs, AgNCs, and AgNPLs, there is evidence that discriminates shape as a driver of toxicity since sublethal responses generally were observed to follow a pattern, suggesting toxicity is most significant for AgNSs followed by AgNPLs and then AgNCs, which is the least toxic. Sum frequency generation vibrational spectroscopy showed that irrespective of size or shape, all hybrid lipid-coated AgNPs interact with membrane surfaces and "snorkel" between phases into the lipid monolayer with minimal energetic cost. These findings decisively demonstrate that not only smaller AgNPs but also the shape of the AgNPs influences their biological compatibility.

Effects of PFAS on human liver transporters: implications for health outcomes.

Per- and polyfluoroalkyl substances (PFAS) have become internationally recognized over the past three decades as persistent organic pollutants used in the production of various consumer and industrial goods. Research efforts continue to gauge the risk that historically used, and newly produced, PFAS may cause to human health. Numerous studies report toxic effects of PFAS on the human liver as well as increased serum cholesterol levels in adults. A major concern with PFAS, also dubbed "forever chemicals," is that they accumulate in the liver and kidney and persist in serum. The mechanisms responsible for their disposition and excretion in humans are poorly understood. A better understanding of the interaction of PFAS with liver transporters, as it pertains to the disposition of PFAS and other xenobiotics, could provide mechanistic insight into human health effects and guide efforts toward risk assessment of compounds in development. This review summarizes the current state of the literature on the emerging relationships (eg, substrates, inhibitors, modulators of gene expression) between PFAS and specific hepatic transporters. The adaptive and toxicological responses of hepatocytes to PFAS that reveal linkages to pathologies and epidemiological findings are highlighted. The evidence suggests that our understanding of the molecular landscape of PFAS must improve to determine their impact on the expression and function of hepatocyte transporters that play a key role in PFAS or other xenobiotic disposition. From here, we can assess what role these changes may have in documented human health outcomes.

Enriched housing differentially alters allostatic load and cardiopulmonary responses to wildfire-related smoke in male and female mice

ABSTRACT Living conditions are an important modifier of individual health outcomes and may lead to higher allostatic load (AL). However, housing-induced cardiovascular and immune effects contributing to altered environmental responsiveness remain understudied. This investigation was conducted to examine the influence of enriched (EH) versus depleted housing (DH) conditions on cardiopulmonary functions, systemic immune responses, and allostatic load in response to a single wildfire smoke (WS) exposure in mice. Male and female C57BL/6J mice were divided into EH or DH for 22 weeks, and cardiopulmonary assessments measured before and after exposures to either one-hr filtered air (FA) or flaming eucalyptus WS exposure. Male and female DH mice exhibited increased heart rate (HR) and left ventricular mass (LVM), as well as reduced stroke volume and end diastolic volume (EDV) one week following exposure to WS. Female DH mice displayed significantly elevated levels of IL-2, IL-17, corticosterone and hemoglobin A1c (HbA1c) following WS, while female in EH mice higher epinephrine levels were detected. Female mice exhibited higher AL than males with DH, which was potentiated post-WS exposure. Thus, DH increased susceptibility to extreme air pollution in a gender-dependent manner suggesting that living conditions need to be evaluated as a modifier of toxicological responses.

In vitro toxicity evaluation in A549 cells of diesel particulate matter from two different particle sampling systems and several resuspension media.

In urban areas, inhalation of fine particles from combustion sources such as diesel engines causes adverse health effects. For toxicity testing, a substantial amount of particulate matter (PM) is needed. Conventional sampling involves collection of PM onto substrates by filtration or inertial impaction. A major drawback to those methodologies is that the extraction process can modify the collected particles and alter their chemical composition. Moreover, prior to toxicity testing, PM samples need to be resuspended, which can alter the PM sample even further. Lastly, the choice of the resuspension medium may also impact the detected toxicological responses. In this study, we compared the toxicity profile of PM obtained from two alternative sampling systems, using in vitro toxicity assays. One system makes use of condensational growth before collection in water in an impinger - BioSampler (CG-BioSampler), and the other, a Dekati® Gravimetric Impactor (DGI), is based on inertial impaction. In addition, various methods for resuspension of DGI collected PM were compared. Tested endpoints included cytotoxicity, formation of cellular reactive oxygen species, and genotoxicity. The alternative collection and suspension methods affected different toxicological endpoints. The water/dimethyl sulfoxide mixture and cell culture medium resuspended particles, along with the CG-BioSampler sample, produced the strongest responses. The water resuspended sample from the DGI appeared least toxic. CG-BioSampler collected PM caused a clear increased response in apoptotic cell death. We conclude that the CG-BioSampler PM sampler is a promising alternative to inertial impaction sampling.

Genetic architecture of the toxicological response to eucalyptol and citronellal in Drosophila melanogaster

The excessive and indiscriminate use of synthetic insecticides has led to environmental pollution, wildlife destruction, and adverse effects on human health, while simultaneously giving rise to resistance in insect pest populations. This adaptive trait is expressed through various mechanisms, such as changes in the cuticle, heightened activities of detoxifying enzymes, and alterations in the sites of action that reduce their affinity for insecticides. In this context, we associate variation in toxicological response with genomic variation, to identify genetic polymorphisms underlying the different steps of the insect (genotype)-response (phenotype)-insecticide (environment) interaction. Under this framework, our objective was to investigate the genetic factors involved in the toxicological response of D. melanogaster lines when exposed to citronellal and eucalyptol vapors (monoterpenes of plant origin). We quantified KT50 in adult males, representing the time necessary for half of the exposed individuals to be turned upside down (unable to walk or fly). Since the genomes of all lines used are completely sequenced, we perform a Genome Wide Association Study to analyze the genetic underpinnings of the toxicological response. Our investigation enabled the identification of 656 genetic polymorphisms and 316 candidate genes responsible for the overall phenotypic variation. Among these, 162 candidate genes (77.1%) exhibited specificity to citronellal, 45 (21.4%) were specific to eucalyptol, and 3 candidate genes (1.5%) namely CG34345, robo2, and Ac13E, were implicated in the variation for both monoterpenes. These suggest a widespread adaptability in the response to insecticides, encompassing genes influenced by monoterpenes and those orchestrating resistance to the toxicity of these compounds.

Lack of detectable sex differences in the mitochondrial function of Caenorhabditis elegans

BackgroundSex differences in mitochondrial function have been reported in multiple tissue and cell types. Additionally, sex-variable responses to stressors including environmental pollutants and drugs that cause mitochondrial toxicity have been observed. The mechanisms that establish these differences are thought to include hormonal modulation, epigenetic regulation, double dosing of X-linked genes, and the maternal inheritance of mtDNA. Understanding the drivers of sex differences in mitochondrial function and being able to model them in vitro is important for identifying toxic compounds with sex-variable effects. Additionally, understanding how sex differences in mitochondrial function compare across species may permit insight into the drivers of these differences, which is important for basic biology research. This study explored whether Caenorhabditis elegans, a model organism commonly used to study stress biology and toxicology, exhibits sex differences in mitochondrial function and toxicant susceptibility. To assess sex differences in mitochondrial function, we utilized four male enriched populations (N2 wild-type male enriched, fog-2(q71), him-5(e1490), and him-8(e1498)). We performed whole worm respirometry and determined whole worm ATP levels and mtDNA copy number. To probe whether sex differences manifest only after stress and inform the growing use of C. elegans as a mitochondrial health and toxicologic model, we also assessed susceptibility to a classic mitochondrial toxicant, rotenone.ResultsWe detected few to no large differences in mitochondrial function between C. elegans sexes. Though we saw no sex differences in vulnerability to rotenone, we did observe sex differences in the uptake of this lipophilic compound, which may be of interest to those utilizing C. elegans as a model organism for toxicologic studies. Additionally, we observed altered non-mitochondrial respiration in two him strains, which may be of interest to other researchers utilizing these strains.ConclusionsBasal mitochondrial parameters in male and hermaphrodite C. elegans are similar, at least at the whole-organism level, as is toxicity associated with a mitochondrial Complex I inhibitor, rotenone. Our data highlights the limitation of using C. elegans as a model to study sex-variable mitochondrial function and toxicological responses.

Deciphering styrene oxide tolerance mechanisms in Gluconobacter oxydans mutant strain

Chemical production wastewater contains large amounts of organic solvents (OSs), which pose a significant threat to the environment. In this study, a 10 g·L−1 styrene oxide tolerant strain with broad-spectrum OSs tolerance was obtained via adaptive laboratory evolution. The mechanisms underlying the high OS tolerance of tolerant strain were investigated by integrating physiological, multi-omics, and genetic engineering analyses. Physiological changes are one of the main factors responsible for the high OS tolerance in mutant strains. Moreover, the P-type ATPase GOX_RS04415 and the LysR family transcriptional regulator GOX_RS04700 were also verified as critical genes for styrene oxide tolerance. The tolerance mechanisms of OSs can be used in biocatalytic chassis cell factories to synthesize compounds and degrade environmental pollutants. This study provides new insights into the mechanisms underlying the toxicological response to OS stress and offers potential targets for enhancing the solvent tolerance of G. oxydans.

Characterizing the toxicological responses to inorganic arsenicals and their metabolites in immortalized human bladder epithelial cells.

Arsenic is highly toxic to the human bladder. In the present study, we established a human bladder epithelial cell line that closely mimics normal human bladder epithelial cells by immortalizing primary uroplakin 1B-positive human bladder epithelial cells with human telomerase reverse transcriptase (HBladEC-T). The uroplakin 1B-positive human bladder epithelial cell line was then used to evaluate the toxicity of seven arsenicals (iAsV, iAsIII, MMAV, MMAIII, DMAV, DMAIII, and DMMTAV). The cellular uptake and metabolism of each arsenical was different. Trivalent arsenicals and DMMTAV exhibited higher cellular uptake than pentavalent arsenicals. Except for MMAV, arsenicals were transported into cells by aquaglyceroporin 9 (AQP9). In addition to AQP9, DMAIII and DMMTAV were also taken up by glucose transporter 5. Microarray analysis demonstrated that arsenical treatment commonly activated the NRF2-mediated oxidative stress response pathway. ROS production increased with all arsenicals, except for MMAV. The activating transcription factor 3 (ATF3) was commonly upregulated in response to oxidative stress in HBladEC-T cells: ATF3 is an important regulator of necroptosis, which is crucial in arsenical-induced bladder carcinogenesis. Inorganic arsenics induced apoptosis while MMAV and DMAIII induced necroptosis. MMAIII, DMAV, and DMMTAV induced both cell death pathways. In summary, MMAIII exhibited the strongest cytotoxicity, followed by DMMTAV, iAsIII, DMAIII, iAsV, DMAV, and MMAV. The cytotoxicity of the tested arsenicals on HBladEC-T cells correlated with their cellular uptake and ROS generation. The ROS/NRF2/ATF3/CHOP signaling pathway emerged as a common mechanism mediating the cytotoxicity and carcinogenicity of arsenicals in HBladEC-T cells.

Redox-activity and in vitro effects of regional atmospheric aerosol pollution: Seasonal differences and correlation between oxidative potential and in vitro toxicity of PM1

Particulate Matter (PM) is a complex and heterogeneous mixture of atmospheric particles recognized as a threat to human health. Oxidative Potential (OP) measurement is a promising and integrative method for estimating PM-induced health impacts since it is recognized as more closely associated with adverse health effects than ordinarily used PM mass concentrations. OP measurements could be introduced in the air quality monitoring, along with the parameters currently evaluated. PM deposition in the lungs induces oxidative stress, inflammation, and DNA damage.The study aimed to compare the OP measurements with toxicological effects on BEAS-2B and THP-1 cells of winter and summer PM1 collected in the Po Valley (Italy) during 2021. PM1 was extracted in deionized water by mechanical agitation and tested for OP and, in parallel, used to treat cells. Cytotoxicity, genotoxicity, oxidative stress, and inflammatory responses were assessed by MTT test, DCFH-DA assay, micronucleus, γ-H2AX, comet assay modified with endonucleases, ELISA, and Real-Time PCR. The evaluation of OP was performed by applying three different assays: dithiothreitol (OPDTT), ascorbic acid (OPAA), and 2′,7′-dichlorofluorescein (OPDCFH), in addition, the reducing potential was also analysed (RPDPPH).Seasonal differences were detected in all the parameters investigated. The amount of DNA damage detected with the Comet assay and ROS formation highlights the presence of oxidative damage both in winter and in summer samples, while DNA damage (micronucleus) and genes regulation were mainly detected in winter samples. A positive correlation with OPDCFH (Spearman's analysis, p < 0.05) was detected for IL-8 secretion and γ-H2AX.These results provide a biological support to the implementation in air quality monitoring of OP measurements as a useful proxy to estimate PM-induced cellular toxicological responses. In addition, these results provide new insights for the assessment of the ability of secondary aerosol in the background atmosphere to induce oxidative stress and health effects.

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.

Insight into the relationship between metabolic enzymes and oxadiazon degradation in Oryza sativa for reducing environmental risks

Oxadiazon (ODZ) is extensively utilized in agricultural fields for weed control owing to its strong effectiveness. However, excessive loading of ODZ in water bodies and agricultural soils can lead to various environmental concerns. Therefore, it is crucial to understand the ODZ metabolic process and associated mechanisms in crops to assess the likelihood of ODZ contamination in the environment. This study aimed to assess the effects of ODZ on the growth and toxicological responses of rice (Oryza sativa). The growth of rice tissues was notably compromised with the increase in ODZ concentrations. RNA sequencing in combination with liquid chromatography–quadrupole-time-of-flight–high-resolution mass spectrometry/mass spectrometry (LC–Q-TOF–HRMS/MS) analysis allowed for the identification of numerous transcriptional components associated with ODZ metabolism. Four libraries comprising rice roots and shoots exposed to ODZ were RNA-sequenced in triplicate. The application of environmentally realistic ODZ concentrations upregulated the expression of 844 genes in shoots and 1476 genes in roots. Gene enrichment analysis revealed the presence of multiple enzymes involved in ODZ metabolism and detoxification. These enzymes play a critical role in mitigating environmental stress and facilitating xenobiotic metabolism. Notably, among differentially expressed genes, several key enzymes were identified, including cytochrome P450s, protein kinases, aminotransferases, and ATP-binding cassette transporters involved in the metabolic process. Using LC–Q-TOF–HRMS/MS, 3 metabolites and 13 conjugates were identified in multiple metabolic pathways involving oxidation, hydrolysis, glycosylation, acetylation, and methylation. This study successfully established a potential link between the specific metabolic products of ODZ and increased activities of their corresponding enzymes. Moreover, this study considerably elucidates the detailed pathways and mechanisms involved in ODZ metabolism. The study findings provide valuable insights into the development of genotypes for reducing ODZ residues in paddy fields and minimizing their accumulation in rice crops.

The Role of Aryl Hydrocarbon Receptor in the Pathogenesis and Treatment of Psoriasis.

The pathogenesis of psoriasis is complex. Aryl hydrocarbon receptor (AhR) is a transcription factor that can be bound and activated by structurally diverse ligands and plays an important role in a range of biological processes and in the pathogenesis of different diseases. Recently, the role of AhR in psoriasis has attracted attention. AhR has toxicological functions and physiological functions. The overexpression and activation of AhR induced by the environmental pollutant and exogenous AhR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can drive the development of psoriasis. This TCDD-mediated toxicological response disrupts the physiological functions of AhR resulting in skin barrier disorders and the release of inflammatory cytokines, 2 of the pivotal factors of psoriasis. In addition, highly upregulated kynureninase in psoriasis decreases endogenous AhR agonists, thereby weakening the physiological functions of AhR. Activating AhR physiological signalling should be useful in the treatment of psoriasis. Studies have demonstrated that physiological activation of AhR can dampen the severity of psoriasis. The oldest and effective treatment for psoriasis coal tar works by activating AhR, and both new anti-psoriasis drugs tapinarof and benvitimod are formulations of AhR agonist, supporting that activation of AhR can be used as a new strategy for the treatment of psoriasis. Preclinical and preliminary clinical studies have revealed the anti-psoriasis effects of a number of AhR agonists, providing potential candidates for the development of new drugs for the treatment of psoriasis.

ScRNA-seq analysis discovered suppression of immunomodulatory dependent inflammatory response in PMBCs exposed to silver nanoparticles

The assessment of AgNPs toxicity in vitro and in vivo models are frequently conflicting and inaccurate. Nevertheless, single cell immunological responses in a heterogenous environment have received little attention. Therefore, in this study, we have performed in-depth analysis which clearly revealed cellular-metal ion association as well as specific immunological response. Our study didn’t show significant population differences in PMBC between control and AgNPs group implying no toxicological response. To confirm it further, deep profiling identified differences in subsets and differentially expressed genes (DEGs) of monocytes, B cells and T cells. Notably, monocyte subsets showed significant upregulation of metallothionein (MT) gene expression such as MT1G, MT1X, MT1E, MT1A, and MT1F. On the other hand, downregulation of pro-inflammatory genes such as IL1β and CCL3 in both CD16 + and CD16- monocyte subsets were observed. This result indicated that AgNPs association with monocyte subsets de-promoted inflammatory responsive genes suggesting no significant toxicity observed in AgNPs treated group. Other cell types such as B cells and T cells also showed negligible differences in their subsets suggesting no toxicity response. Further, AgNPs treated group showed upregulation of cell proliferation, ribosomal synthesis, downregulation of cytokine release, and T cell differentiation inhibition. Overall, our results conclude that treatment of AgNPs to PMBC cells didn’t display immunological related cytotoxicity response and thus motivate researchers to use them actively for biomedical applications.

Mechanism of the Synergistic Toxicity of Ampicillin and Cefazoline on Selenastrum capricornutum.

Ampicillin (AMP) and cefazolin (CZO) are commonly used β-lactam antibiotics which are extensively globally produced. Additionally, AMP and CZO are known to have relatively high ecotoxicity. Notably, the mix of AMP and CZO creates a synergistic effect that is more harmful to the environment, and how exposure to AMP-CZO can induce synergism in algae remains virtually unknown. To yield comprehensive mechanistic insights into chemical toxicity, including dose-response relationships and variations in species sensitivity, the integration of multiple endpoints with de novo transcriptomics analyses were used in this study. We employed Selenastrum capricornutum to investigate its toxicological responses to AMP and CZO at various biological levels, with the aim of elucidating the underlying mechanisms. Our assessment of multiple endpoints revealed a significant growth inhibition in response to AMP at the relevant concentrations. This inhibition was associated with increased levels of reactive oxygen species (ROS) and perturbations in nitrogen metabolism, carbohydrate metabolism, and energy metabolism. Growth inhibition in the presence of CZO and the AMP-CZO combination was linked to reduced viability levels, elevated ROS production, decreased total soluble protein content, inhibited photosynthesis, and disruptions in the key signaling pathways related to starch and sucrose metabolism, ribosome function, amino acid biosynthesis, and the production of secondary metabolites. It was concluded from the physiological level that the synergistic effect of Chlorophyll a (Chla) and Superoxide dismutase (SOD) activity strengthened the growth inhibition of S. capricornutum in the AMP-CZO synergistic group. According to the results of transcriptomic analysis, the simultaneous down-regulation of LHCA4, LHCA1, LHCA5, and sodA destroyed the functions of the photosynthetic system and the antioxidant system, respectively. Such information is invaluable for environmental risk assessments. The results provided critical knowledge for a better understanding of the potential ecological impacts of these antibiotics on non-target organisms.

Effects of primary leachates of conventional and alternative plastics in Cyprinodon variegatus fish larvae: Endocrine disruption and toxicological responses

The inclusion of hazardous substances in the formulation of plastics raises significant concerns, particularly, if those substances are released as primary leachates during plastic degradation and/or fragmentation. In this sense, the production of degradable plastics holding deleterious additives can increase the release of harmful substances into the environment. Additionally, the effects of primary leachates of “eco-friendly” materials remain unexplored. To address this, we performed exposures to primary leachates of alternative polymers, and commercial bags to verify possible responses associated with endocrine disruption and/or activation of the detoxification pathway in larvae of the marine fish model Cyprinodon variegatus.The chemical characterization evidenced a great number of additives in the formulation of the materials analyzed in this study. Those include, except for the PLA sample, relevant levels of the hazardous phthalates DEHP and DiBP.Regarding the effects on marine fish larvae, exposure to leachates from alternative polymers (10 g/L) PHB and PHBV produced remarkable mortality (100%). While the exposure to bag leachates of all tested materials (1 and 10 g/L) produced alterations in biomarkers for steroidogenic and detoxification pathways. To a lesser extent (10 g/L), three materials produced significant alterations in estrogenic biomarkers (Home-compostable bag 1, LDPE and Recycled PE bags). Although the alterations in gene expression were not directly correlated to the amount of DEHP or DiBP, we can conclude that primary leachates of “eco-friendly” bags are harmful to marine vertebrates.

Toxicological Response of Zebrafish Exposed to Cocktails of Polymeric Materials and Valproic Acid

Microplastic pollution represents an emerging problem of great interest in the public domain in the last decade; in addition, it overlaps with another delicate problem—pollution with pharmaceutical products that can have negative effects on the environment and people, even in small amounts. The main purpose of this study was to assess the biochemical and behavioral effects of exposure of adult zebrafish (Danio rerio) to polyethylene (PE), polypropylene (PP) and valproic acid (VPA), respectively to their mixtures—possible situations in natural aquatic environments. In terms of behavioral responses, sociability appears to be more impaired in the PP group after 5 days of exposure. The mechanisms affected are more those of swimming performance than of sociability. Even more, VPA increases presence in the arm with conspecifics but decreases mobility and locomotion, indicating a possible anxiety mechanism. The mixtures decrease the aggressiveness, especially in the case of the PE+VPA group, where it reaches a super low level compared to the control, which could endanger the species in nature. Regarding the anxiogenic effect, PP and PE act differently: if PE has an anxiogenic effect, on the opposite side is the PP group, which shows a bolder and more agitated behavior. All four variants showed behavioral changes indicative of toxicity from the first dose.

Toxicological evaluation and concentration of airborne PM0.1 in high air pollution period in Guangzhou, China

The emissions and exposure limits for airborne PM0.1 are lacking, with limited scientific data for toxicity. Therefore, we continuously monitored and calculated the number and mass concentrations of airborne PM0.1 in December 2017, January 2018 and March 2018 during the high pollution period in Guangzhou. We collected PM0.1 from the same period and analyzed their chemical components. A549, THP-1 and A549/THP-1 co-cultured cells were selected for exposure to PM0.1, and evaluated for toxicological responses. Our aims are to 1) measure and analyze the number and mass concentrations, and chemical components of PM0.1; 2) evaluate and compare PM0.1 toxicity to different airway cells models at different time points. Guangzhou had the highest mass concentration of PM0.1 in December 2017, while the number concentration was the lowest. Chemical components in PM0.1 vary significantly at different time periods, and the correlation between the chemical composition or source of PM0.1 and the mass and number concentration of PM0.1 was dissimilar. Exposure to PM0.1 disrupted cell membranes, impaired mitochondrial function, promoted the expression of inflammatory mediators, and interfered with DNA replication in the cell cycle. The damage caused by exposure to PM0.1 at different times exhibited variations across different types of cells. PM0.1 in March 2018 stimulated co-cultured cells to secrete more inflammatory mediators, and CMA was significantly related to the expression of them. Our study indicates that it is essential to monitor both the mass and number concentrations of PM0.1 throughout all seasons annually, as conventional toxicological experiments and the internal components of PM0.1 may not effectively reveal the health damages caused by elevated number levels of PM0.1.

COMPARATIVE STUDY FOR RESPONSE TO Cycas circinalis-INDUCED TOXICITY IN LIVER, KIDNEY AND COLON OF RATS AND GUINEA PIGS

This study evaluated the toxicological response of rats and guinea pigs to Cycas in feed. Ten rats and guinea pigs were randomly designated into two groups for each animal. The control groups were fed with a normal diet while the experimental groups were fed with the Cycas-containing feed for 6 weeks. The effect of the Cycas feed on the animals’ liver, kidney, and colon were evaluated using biochemical and histological assays. The result of the experiment showed changes in body weight and tissue (liver, kidney, and colon) antioxidant levels. Additionally, the animals on the Cycas diet observed an increase in oxidative stress and lipid peroxidation. The histology result for both the rats and guinea pigs revealed that cycasin present in the plant is a potent colon carcinogen, it induced hyperplasia in the colon cells which is a great pointer towards abnormal cell division and hence cancer. We predicted that the plant via its induction of oxidative damage and depletion of tissue antioxidants could drive tissue toward tumorigenesis in both animals. There were significant changes between the (p&lt;0.05) values derived from the different animals. Guinea pigs were more susceptible to the negative effects of the cycasin.

Proteome changes in larval zebrafish (Danio rerio) and fathead minnow (Pimephales promelas) exposed to (±) anatoxin-a

Anatoxin-a and its analogues are potent neurotoxins produced by several genera of cyanobacteria. Due in part to its high toxicity and potential presence in drinking water, these toxins pose threats to public health, companion animals and the environment. It primarily exerts toxicity as a cholinergic agonist, with high affinity at neuromuscular junctions, but molecular mechanisms by which it elicits toxicological responses are not fully understood. To advance understanding of this cyanobacteria, proteomic characterization (DIA shotgun proteomics) of two common fish models (zebrafish and fathead minnow) was performed following (±) anatoxin-a exposure. Specifically, proteome changes were identified and quantified in larval fish exposed for 96 h (0.01–3 mg/L (±) anatoxin-a and caffeine (a methodological positive control) with environmentally relevant treatment levels examined based on environmental exposure distributions of surface water data. Proteomic concentration - response relationships revealed 48 and 29 proteins with concentration - response relationships curves for zebrafish and fathead minnow, respectively. In contrast, the highest number of differentially expressed proteins (DEPs) varied between zebrafish (n = 145) and fathead minnow (n = 300), with only fatheads displaying DEPs at all treatment levels. For both species, genes associated with reproduction were significantly downregulated, with pathways analysis that broadly clustered genes into groups associated with DNA repair mechanisms. Importantly, significant differences in proteome response between the species was also observed, consistent with prior observations of differences in response using both behavioral assays and gene expression, adding further support to model specific differences in organismal sensitivity and/or response. When DEPs were read across from humans to zebrafish, disease ontology enrichment identified diseases associated with cognition and muscle weakness consistent with the prior literature. Our observations highlight limited knowledge of how (±) anatoxin-a, a commonly used synthetic racemate surrogate, elicits responses at a molecular level and advances its toxicological understanding.