Molecular Mechanisms of Developmental Toxicity Induced by Graphene Oxide at Predicted Environmental Concentrations

Mechanisms of surface groups regulating developmental toxicity of graphene-based nanomaterials via glycerophospholipid metabolic pathway

Surface modification of graphene-based nanomaterials (GBNs) may occur in aquatic environment and during intentional preparation. However, the influence of the surface groups on the developmental toxicity of GBNs has not been determined. In this study, we evaluated the developmental toxicity of three GBNs including GO (graphene oxide), RGO (reduced GO) and RGO-N (aminated RGO) by employing zebrafish embryos at environmentally relevant concentrations (1-100 μg/L), and the underlying metabolic mechanisms were explored. The results showed that both GO and RGO-N disturbed the development of zebrafish embryos, and the adverse effect of GO was greater than that of RGO-N. Furthermore, the oxygen-containing groups of GBNs play a more important role in inducing developmental toxicity compared to size, defects and nitrogen-containing groups. Specifically, the epoxide and hydroxyl groups of GBNs increased their intrinsic oxidative potential, promoted the generation of ROS, and caused lipid peroxidation. Moreover, a significant decrease in guanosine and abnormal metabolism of multiple glycerophospholipids were observed in all three GBN-treated groups. Nevertheless, GO exposure triggered more metabolic activities related to lipid peroxidation than RGO or RGO-N exposure, and the disturbance intensity of the same metabolite was greater than that of the other two agents. These findings reveal underlying metabolic mechanisms of GBN-induced developmental toxicity.

Antimony trioxide nanoparticles promote ferroptosis in developing zebrafish (Danio rerio) by disrupting iron homeostasis

The widespread use of antimony trioxide (ATO) and ATO nanoparticles (nATO) has led to increasing ecological and health risks. However, there is relatively insufficient research on the aquatic ecotoxicology of nATO. This study revealed that nATO affects the development of zebrafish embryos and mainly induces ferroptosis through the dissolution of Sb(III). The size of nATO ranged from 50 to 250 nm, and it generated free radicals in water. It can be ingested and accumulate in zebrafish larvae and affects normal development. Compared with those in the control group, the levels of reactive oxygen species (ROS), cell apoptosis, mitochondrial damage and iron content in the group exposed to high concentrations of nATO were increased. The transcriptomics results indicated that nATO significantly altered the expression levels of key genes related to glutathione metabolism and ferroptosis. Quantitative polymerase chain reaction consistently demonstrated the reliability of the transcriptome data and revealed that nATO induced ferroptosis by disrupting iron homeostasis and the key factor is the dissolution of Sb(III). Furthermore, ferrostatin-1, an inhibitor of ferroptosis, decreased the levels of ROS, apoptosis and mitochondrial damage induced by nATO, which further prove that nATO can promote ferroptosis. This work deepens the understanding of the ecological toxicological effects of nATO in aquatic environments and its mechanisms, which is highly important for the development of antimony management strategies.

Toxicity and related molecular mechanisms of Sb(III) in the embryos and larvae of zebrafish (Danio rerio)

Antimony (Sb) pollution poses a severe threat to humans and ecosystems due to the extensive use of Sb in various fields. However, little is known about the toxic effects of Sb and its aquatic ecotoxicological mechanism. This study aimed to reveal the toxicity and related molecular mechanisms of trivalent Sb (Sb(III)) in zebrafish embryos/larvae. Sb(III) accumulated in larvae, which correlated with the exposure concentration. Although no significant lethal or teratogenic effects were observed, normal growth and development were affected. Exposure to 10 or 20 mg/L Sb(III) increased the levels of reactive oxygen species in the larvae while enhancing catalase activity and increasing cell apoptosis. Transcriptomic analysis revealed that Sb(III) promoted glutathione metabolism and the ferroptosis pathway. In addition, symptoms associated with ferroptosis, including mitochondrial damage, biochemical levels of related molecules and increased tissue iron content, were detected. Quantitative polymerase chain reaction (qPCR) analyses further confirmed that Sb(III) significantly altered the transcription levels of genes related to the ferroptosis pathway by disrupting iron homeostasis. Furthermore, ferrostatin-1 (Fer-1) mitigated the toxic effects induced by Sb(III) in zebrafish. Our research fills the gap in the literature on the toxicity and mechanism of Sb(III) in aquatic organisms, which is highly important for understanding the ecological risks associated with Sb.

Contribution of Immune Responses to the Cardiotoxicity and Hepatotoxicity of Deltamethrin in Early Life Stage Zebrafish (Danio rerio)

Deltamethrin (DM) is a widely used insecticide that has demonstrated developmental toxicity in the early life stages of fish. To better characterize the underlying mechanisms, embryos from Tg(cmlc2:RFP), Tg(apo14:GFP), and Tg(mpx:GFP) transgenic strains of zebrafish were exposed to nominal DM concentrations of 0.1, 1, 10, 25, and 50 μg/L until 120 h post-fertilization (hpf). Heart size increased 56.7%, and liver size was reduced by 17.1% in zebrafish exposed to 22.7 and 24.2 μg/L DM, respectively. RNA sequencing and bioinformatic analyses predicted that key biological processes affected by DM exposure were related to inflammatory responses. Expression of IL-1 protein was increased by 69.0% in the 24.4 μg/L DM treatment, and aggregation of neutrophils in cardiac and hepatic histologic sections was also observed. Coexposure to resatorvid, an anti-inflammatory agent, mitigated inflammatory responses and cardiac toxicity induced by DM and also restored liver biomass. Our data indicated a complex proinflammatory mechanism underlying DM-induced cardiotoxicity and hepatotoxicity which may be important for key events of adverse outcomes and associated risks of DM to early life stages of fish.

Effects of perfluorooctanoic acid on the nutritional quality of Mytilus edulis

Perfluorooctanoic acid (PFOA), which widely presents in marine environment, may produce some adverse effects to aquatic organism. Mytilus edulis are popular due to their high protein and low fat content in China. However, few studies have investigated the effects of PFOA on the quality of aquatic products. Here, PFOA effects on basic nutritional indices in M. edulis were measured, and possible mechanisms were explored. PFOA caused clear variation in physiological and biochemical indices of M. edulis. The contents of some important proteins, nutrients, and amino acids etc. dropped. Integrating metabolomics data, we speculate PFOA exposure triggered inflammation and oxidative stress in mussels, interfered with the metabolic pathways related to the quality and the transport and absorption pathways of metal ions, and affected the levels of some important elements and metabolites, thus decreasing the nutritional quality of M. edulis. The study provides new insights into PFOA adverse effects to marine organism, and may offer some references for some researchers to assess food quality and ecological risk to pollutants.

Hepatotoxicity and lipid metabolism disorders of 8:2 polyfluoroalkyl phosphate diester in zebrafish: In vivo and in silico evidence

8:2 polyfluoroalkyl phosphate diester (8:2 diPAP) has been shown to accumulate in the liver, but whether it induces hepatotoxicity and lipid metabolism disorders remains largely unknown. In this study, zebrafish embryos were exposed to 8:2 diPAP for 7 d. Hepatocellular hypertrophy and karyolysis were noted after exposure to 0.5 ng/L 8:2 diPAP, suggesting suppressed liver development. Compared to the water control, 8:2 diPAP led to significantly higher triglyceride and total cholesterol levels, but markedly lower levels of low-density lipoprotein, implying disturbed lipid homeostasis. The levels of two peroxisome proliferator activated receptor (PPAR) subtypes (pparα and pparγ) involved in hepatotoxicity and lipid metabolism were significantly upregulated by 8:2 diPAP, consistent with their overexpression as determined by immunohistochemistry. In silico results showed that 8:2 diPAP formed hydrogen bonds with PPARα and PPARγ. Among seven machine learning models, Adaptive Boosting performed the best in predicting the binding affinities of PPARα and PPARγ on the test set. The predicted binding affinity of 8:2 diPAP to PPARα (7.12) was higher than that to PPARγ (6.97) by Adaptive Boosting, which matched well with the experimental results. Our results revealed PPAR - mediated adverse effects of 8:2 diPAP on the liver and lipid metabolism of zebrafish larvae.

Sluggish and Ion-Resilient Behavior of Interfacial Aqueous Layer on Single-Layer Graphene Oxide: Insights from In Situ Atomic Force Microscopy

Understanding interfacial interactions of graphene oxide (GO) is important to evaluate its colloidal behavior and environmental fate. Single-layer GO is the fundamental unit of GO colloids, and its interfacial aqueous layers critically dictate these interfacial interactions. However, conventional techniques like X-ray diffraction are limited to multilayer systems and are inapplicable to single-layer GO. Therefore, our study employed atomic force microscopy to precisely observe the in situ dynamic behaviors of interfacial aqueous layers on single-layer GO. The interfacial aqueous layer height was detected at the subnanometer level. In real-time monitoring, the single-layer height increased from 1.17 to 1.70 nm within 3 h immersion. This sluggish process is different from the rapid equilibration of multilayer GO in previous studies, underscoring a gradual transition in hydration kinetics. Ion strength exhibited negligible influence on the single-layer height, suggesting a resilient response of the interfacial aqueous layer to ion-related perturbations due to intricate ion interactions and electrical double-layer compression. Humic acid led to a substantial increase in the interfacial aqueous layers, improving the colloidal stability of GO and augmenting its potential for migration. These findings hold considerable significance regarding the environmental behaviors of the GO interfacial aqueous layer in ion- and organic-rich water and soil.

Exploring the Effects of Graphene-Based Nanoparticles on Early Salmonids Cardiorespiratory Responses, Swimming and Nesting Behavior

Graphene-based nanomaterials are exceptionally attractive for a wide range of applications, raising the likelihood of the release of graphene-containing nanoparticles into aquatic environments. The growing use of these carbon nanomaterials in different industries highlights the crucial need to investigate their environmental impact and evaluate potential risks to living organisms. The current investigation evaluated the nanotoxicity of graphene (nanoflakes) and graphene oxide (GO) nanoparticles on the cardiorespiratory responses (heart rate, gill ventilation frequency), as well as the swimming and nesting behavioral parameters of early stage larvae and juvenile salmonids. Both short-term (96 h) and long-term (23 days) exposure experiments were conducted using two common species: brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss). The findings demonstrated notable alterations in fish nesting behavior, swimming performance, and cardiorespiratory functions, indicating the potential toxicity of nanoparticles. This impact was observed at both physiological and whole-organismal levels in salmonids at early stages. Future investigations should explore different types of nanocarbons and their potential enduring effects on fish population structure, considering not only individual survival but also broader aspects of development, including feeding, reproductive, and other social dynamics.

Identifying the Stripping of Oxide Debris from Graphene Oxide: Evidence from Experimental Analysis and Molecular Simulation

In this study, characteristics of oxidation debris (OD) and its stripping mechanism from graphene oxide (GO) were explored. The results demonstrated that OD contains three components, namely, protein-, fulvic acid-, and humic acid-like substances; among these, protein-like substances with lower molecular weight and higher hydrophilicity were most liable to be stripped from GO and were the primary components stripped from GO at pH < 10, whereas humic acid- and fulvic acid-like substances were stripped from GO at pH > 10. During the stripping of OD, hydrogen bonds from carboxyl and carbonyl were the first to break, followed by hydrogen bonds from epoxy. Subsequently, π-π interactions were broken, and hydrogen bond interactions induced by hydroxyl groups were the hardest to break. After the stripping of OD, the recombination of OD on GO was observed, and regions containing relatively fewer oxygen-containing functional groups were favorable binding sites for the readsorbed OD. The stripping and recombination of OD on GO resulted in an uneven GO surface, which should be considered during the development of GO-based environmental materials and the evaluation of their environmental behavior.

Integrated evidence of transcriptional, metabolic, and intestinal microbiota changes in Ruditapes philippinarum due to perfluorooctanoic acid-induced immunotoxicity

Perfluorooctanoic acid (PFOA) is a toxic pollutant that bioaccumulates and is a significant public health concern due to its ubiquitous and persistent occurrence in global environments. Few studies have evaluated the adverse effects of PFOA on immune system, and this is particularly true for mollusks. Here, the PFOA-associated effects on immune system were evaluated in Ruditapes philippinarum using integrated analysis of metabolomes, microbiomes, and transcriptomes, providing evidence for possible mechanisms related to immunotoxicity. PFOA exposure caused clear variation in several important metabolites related to immune regulatory function within the haemolyph from R. philippinarum, while also altering key metabolic pathways, including those of lipids, unsaturated fatty acids (UFAs), and bile acids (BAs). After exposure to PFOAs, intestinal bacterial communities also clearly changed, with the predominant microflora becoming Mycoplasma and Bacteroidetes that are related to intestinal inflammation. Molecular analyses provided consistent results, wherein the expression of immune-related genes was significantly altered. Integration of the multi-'omics' analyses suggested that the TLR/MyD88/NF-kB pathway, along with PI3K-Akt-mTOR pathway, PPAR-mediated lipid metabolism and the autophagy signaling pathway, likely play important roles in initiating immunotoxic effects in R. philippinarum after PFOA exposure. These results provide further evidence that PFOA exposure can lead to immunologic dysfunction and also provide new insights into the mechanisms of PFAS alteration of bivalve immune function.

Nano-graphene oxide particles induce inheritable anomalies through altered gene expressions involved in oocyte maturation

The inheritable impact of exposure to graphene oxide nanoparticles (GO NPs) on vertebrate germline during critical windows of gamete development remain undetermined to date. Here, we analyzed the transgenerational effects of exposure to nano-graphene oxide particles (nGO) synthesized in house with lateral dimensions 300-600 nm and surface charge of -36.8 mV on different developmental stages of germ cells (GCs): (1) during GCs undergoing early development and differentiation, and (2) during GCs undergoing gametogenesis and maturation in adulthood. Biocompatibility analyses in Japanese medaka embryos showed lethality above 1 µg/ml and also an aberrant increase in germ cell count of both males and females at doses below the lethal dose. However, no lethality or anomalies were evident in adults up to 45 µg/ml. Long term exposure of embryos and adults for 21 days resulted in reduced fecundity. This effect was transmitted to subsequent generations, F1 and F2. Importantly, the inheritable effects of nGO in adults were pronounced at a high dose of 10 µg/ml, while 1 µg/ml showed no impact on the germline indicating lower doses used in this study to be safe. Further, expressions of selected genes that adversely affected oocyte maturation were enhanced in F1 and F2 individuals. Interestingly, the inheritance patterns differed corresponding to the stage at which the fish received the exposure.

Comparative transcriptome analysis of T lymphocyte subpopulations and identification of critical regulators defining porcine thymocyte identity

Introduction

The development and migration of T cells in the thymus and peripheral tissues are crucial for maintaining adaptive immunity in mammals. However, the regulatory mechanisms underlying T cell development and thymocyte identity formation in pigs remain largely underexplored.

Method

Here, by integrating bulk and single-cell RNA-sequencing data, we investigated regulatory signatures of porcine thymus and lymph node T cells.

Results

The comparison of T cell subpopulations derived from porcine thymus and lymph nodes revealed that their transcriptomic differences were influenced more by tissue origin than by T cell phenotypes, and that lymph node cells exhibited greater transcriptional diversity than thymocytes. Through weighted gene co-expression network analysis (WGCNA), we identified the key modules and candidate hub genes regulating the heterogeneity of T cell subpopulations. Further, we integrated the porcine thymocyte dataset with peripheral blood mononuclear cell (PBMC) dataset to systematically compare transcriptomic differences between T cell types from different tissues. Based on single-cell datasets, we further identified the key transcription factors (TFs) responsible for maintaining porcine thymocyte identity and unveiled that these TFs coordinately regulated the entire T cell development process. Finally, we performed GWAS of cell type-specific differentially expressed genes (DEGs) and 30 complex traits, and found that the DEGs in thymus-related and peripheral blood-related cell types, especially CD4_SP cluster and CD8-related cluster, were significantly associated with pig productive and reproductive traits.

Discussion

Our findings provide an insight into T cell development and lay a foundation for further exploring the porcine immune system and genetic mechanisms underlying complex traits in pigs.

New insights into the impact of polystyrene micro/nanoplastics on the nutritional quality of marine jacopever (Sebastes schlegelii)

Microplastics (MPs) and nanoplastics (NPs) are ubiquitous in the marine environments due to the wide use and mismanagement of plastics. However, the effect of MPs/NPs on the nutrition quality of economic species is poorly understood, and their underlying mechanisms remained unclear. We therefore investigated the impacts of polystyrene MPs/NPs on the nutrition composition of marine jacopever Sebastes schlegelii from the perspective of assimilation and metabolism. Results showed that NPs reduced more nutrition quality than MPs. Despite no notable impact on intestinal microbiota function, MPs/NPs influenced the assimilation of fish through intestinal damage. Furthermore, NPs induced greater damage to hepatocyte metabolism than MPs, caused by hepatocyte uptake through membrane protein pumps/channels and clathrin/caveolin-mediated endocytosis for NPs, while through phagocytosis/pinocytosis for MPs. NPs triggered more cell apoptosis signals in Ferroptosis and FoxO signaling pathways than MPs, destroying mitochondria structure. Compared with MP treatments, a significant upregulation of genes (PRODH and SLC25A25A) associated with the electron transfer chain of mitochondria was detected in the NP treatments, influencing the tricarboxylic acid cycle and interfering with liver metabolism of proteins, fatty acid, glycerol phospholipids, and carbohydrates. This work provides new insights into the potential impacts of MPs/NPs on the quality and safety of seafood.

A zebrafish model of Ifih1-driven Aicardi-Goutières syndrome reproduces the interferon signature and the exacerbated inflammation of patients

Type I interferonopathies are a heterogenic group of rare diseases associated with an increase in type I interferon (IFN). The main challenge for the study of Type I interferonopathies is the lack of a well-founded animal model to better characterize the phenotype as well as to perform fast and large drug screenings to offer the best treatment options. In this study, we report the development of a transgenic zebrafish model of Type I interferonopathy overexpressing ifih1 carrying the mutation p.Arg742His (Tg(ifih1_mut)), corresponding to the human mutation p.Arg779His. RNA sequence analysis from Tg(ifih1_mut) larvae revealed a systemic inflammation and IFN signature upon a suboptimal poly I:C induction compared with wild-type larvae, confirming the phenotype observed in patients suffering from Type I interferonopathies. More interestingly, the phenotype was manifested in the zebrafish inflammation and Type I IFN reporters nfkb:eGFP and isg15:eGFP, respectively, making this zebrafish model suitable for future high-throughput chemical screening (HTS). Using the unique advantages of the zebrafish model for gene editing, we have generated Tg(ifih1_mut) knocked down for mavs and ikbke, which completely abrogated the Poly I:C induction and activation of the GFP of the reporters. Finally, we used an FDA-approved drug, Baricitinib (Jak1/Jak2 inhibitor), which was able to reduce the inflammation and the ISG expression. Our results demonstrate the potential of this model to further understand AGS pathological mechanisms and to identify novel therapeutic drugs by HTS.

Abnormality of mussel in the early developmental stages induced by graphene and triphenyl phosphate: In silico toxicogenomic data-mining, in vivo, and toxicity pathway-oriented approach

Increasing number of complex mixtures of organic pollutants in coastal area (especially for nanomaterials and micro/nanoplastics associated chemicals) threaten aquatic ecosystems and their joint hazards are complex and demanding tasks. Mussels are the most sensitive marine faunal groups in the world, and their early developmental stages (embryo and larvae) are particularly susceptible to environmental contaminants, which can distinguish the probable mechanisms of mixture-induced growth toxicity. In this study, the potential critical target and biological processes affected by graphene and triphenyl phosphate (TPP) were developed by mining public toxicogenomic data. And their combined toxic effects were verified by toxicological assay at early developmental stages in filter-feeding mussels (embryo and larvae). It showed that interactions among graphene/TPP with 111 genes (ABCB1, TP53, SOD, CAT, HSP, etc.) affected phenotypes along conceptual framework linking these chemicals to developmental abnormality endpoints. The PPAR signaling pathway, monocarboxylic acid metabolic process, regulation of lipid metabolic process, response to oxidative stress, and gonad development were noted as the key molecular pathways that contributed to the developmental abnormality. Enriched phenotype analysis revealed biological processes (cell proliferation, cell apoptosis, inflammatory response, response to oxidative stress, and lipid metabolism) affected by the investigated mixture. Combined, our results supported that adverse effects induced by contaminants/ mixture could not only be mediated by single receptor signaling or be predicted by the simple additive effect of contaminants. The results offer a framework for better comprehending the developmental toxicity of environmental contaminants in mussels and other invertebrate species, which have considerable potential for hazard assessment of coastal mixture.

The Potentiating Effect of Graphene Oxide on the Arylhydrocarbon Receptor (AhR)-Cytochrome P4501A (Cyp1A) System Activated by Benzo(k)fluoranthene (BkF) in Rainbow Trout Cell Line

The increasing use of graphene oxide (GO) will result in its release into the environment; therefore, it is essential to determine its final fate and possible metabolism by organisms. The objective of this study was to assess the possible role of the aryl hydrocarbon receptor (AhR)-dependent cytochrome P4501A (Cyp1A) detoxification activities on the catabolism of GO. Our hypothesis is that GO cannot initially interact with the AhR, but that after an initial degradation caused by other mechanisms, small fractions of GO could activate the AhR, inducing Cyp1A. The environmental pollutant benzo(k)fluoranthene (BkF) was used for the initial activation of the AhR in the rainbow trout (Oncorhynchus mykiss) cell line RTL-W1. Pre-, co-, and post-exposure experiments with GO were performed and Cyp1A induction was monitored. The strong stimulation of Cyp1A observed in cells after exposure to GO, when BkF levels were not detected in the system, suggests a direct action of GO. The role of the AhR was confirmed by a blockage of the observed effects in co-treatment experiments with αNF (an AhR antagonist). These results suggest a possible role for the AhR and Cyp1A system in the cellular metabolism of GO and that GO could modulate the toxicity of environmental pollutants.

Graphene Quantum Dots Nonmonotonically Influence the Horizontal Transfer of Extracellular Antibiotic Resistance Genes via Bacterial Transformation

Graphene quantum dots (GQDs) coexist with antibiotic resistance genes (ARGs) in the environment. Whether GQDs influence ARG spread needs investigation, since the resulting development of multidrug-resistant pathogens would threaten human health. This study investigates the effect of GQDs on the horizontal transfer of extracellular ARGs (i.e., transformation, a pivotal way that ARGs spread) mediated by plasmids into competent Escherichia coli cells. GQDs enhance ARG transfer at lower concentrations, which are close to their environmental residual concentrations. However, with further increases in concentration (closer to working concentrations needed for wastewater remediation), the effects of enhancement weaken or even become inhibitory. At lower concentrations, GQDs promote the gene expression related to pore-forming outer membrane proteins and the generation of intracellular reactive oxygen species, thus inducing pore formation and enhancing membrane permeability. GQDs may also act as carriers to transport ARGs into cells. These factors result in enhanced ARG transfer. At higher concentrations, GQD aggregation occurs, and aggregates attach to the cell surface, reducing the effective contact area of recipients for external plasmids. GQDs also form large agglomerates with plasmids and thus hindering ARG entrance. This study could promote the understanding of the GQD-caused ecological risks and benefit their safe application.

Differences of functionalized graphene materials on inducing chronic aquatic toxicity through the regulation of DNA damage, metabolism and oxidative stress in Daphnia magna

Graphene can be modified with functional groups when released into the environment. However, very little is known about molecular mechanisms of chronic aquatic toxicity induced by graphene nanomaterials with different surface functional groups. By using RNA sequencing, we investigated the toxic mechanisms of unfunctionalized graphene (u-G), carboxylated graphene (G-COOH), aminated graphene (G-NH₂), hydroxylated graphene (G-OH) and thiolated graphene (G-SH) to Daphnia magna during 21-day exposure. We revealed that alteration of ferritin transcription levels in the "mineral absorption" signaling pathway is a molecular initiating event leading to potential of oxidative stress in Daphnia magna by u-G, while toxic effects of four functionalized graphenes are related to several metabolic pathways including the "protein digestion and absorption" pathway and "carbohydrate digestion and absorption" pathway. The transcription and translation related pathways were inhibited by G-NH₂ and G-OH, which further affected the functions of proteins and normal life activities. Noticeably, detoxifications of graphene and its surface functional derivatives were promoted by increasing the gene expressions related to chitin and glucose metabolism as well as cuticle structure components. These findings demonstrate important mechanistic insights that can potentially be employed for safety assessment of graphene nanomaterials.

Effects of Graphene Oxide Nanosheets in Freshwater Biofilms

Graphene oxide (GO) properties make it a promising material for graphene-based applications in areas such as biomedicine, agriculture, and the environment. Thus, its production is expected to increase, reaching hundreds of tons every year. One GO final destination is freshwater bodies, possibly affecting the communities of these systems. To clarify the effect that GO may impose in freshwater communities, a fluvial biofilm scraped from submerged river stones was exposed to a range (0.1 to 20 mg/L) of GO concentrations during 96 h. With this approach, we hypothesized that GO can: (1) cause mechanical damage and morphological changes in cell biofilms; (2) interfere with the absorption of light by biofilms; (3) and generate oxidative stress, causing oxidative damage and inducing biochemical and physiological alterations. Our results showed that GO did not inflict mechanical damage. Instead, a positive effect is proposed, linked to the ability of GO to bind cations and increase the micronutrient availability to biofilms. High concentrations of GO increased photosynthetic pigment (chlorophyll a, b, and c, and carotenoids) content as a strategy to capture the available light more effectively as a response to the shading effect. A significant increase in the enzymatic (SOD and GSTs activity) and low molecular weight (lipids and carotenoids) antioxidant response was observed, that efficiently reduced oxidative stress effects, reducing the level of peroxidation, and preserving membrane integrity. Being complex entities, biofilms are more similar to environmental communities and may provide more accurate information to evaluate the impact of GO in aquatic systems.

Potential Role of Carbon Nanomaterials in the Treatment of Malignant Brain Gliomas

Malignant gliomas are the most common primary brain tumors in adults up to an extent of 78% of all primary malignant brain tumors. However, total surgical resection is almost unachievable due to the considerable infiltrative ability of glial cells. The efficacy of current multimodal therapeutic strategies is, furthermore, limited by the lack of specific therapies against malignant cells, and, therefore, the prognosis of these in patients is still very unfavorable. The limitations of conventional therapies, which may result from inefficient delivery of the therapeutic or contrast agent to brain tumors, are major reasons for this unsolved clinical problem. The major problem in brain drug delivery is the presence of the blood-brain barrier, which limits the delivery of many chemotherapeutic agents. Nanoparticles, thanks to their chemical configuration, are able to go through the blood-brain barrier carrying drugs or genes targeted against gliomas. Carbon nanomaterials show distinct properties including electronic properties, a penetrating capability on the cell membrane, high drug-loading and pH-dependent therapeutic unloading capacities, thermal properties, a large surface area, and easy modification with molecules, which render them as suitable candidates for deliver drugs. In this review, we will focus on the potential effectiveness of the use of carbon nanomaterials in the treatment of malignant gliomas and discuss the current progress of in vitro and in vivo researches of carbon nanomaterials-based drug delivery to brain.

The impact of various carbon nanomaterials on the morphological, behavioural, and biochemical parameters of rainbow trout in the early life stages

With the increasing production and the number of potential applications of carbon nanomaterials, mainly from the graphene family, their release into the natural environment, especially to aquatic ecosystems, is inevitable. The aim of the study was to determine the effects of various carbon nanomaterials (graphene nanoflakes (GNF), graphene oxide (GO), reduced graphene oxide (RGO) and silicon carbide nanofibers (NFSiC) in the concentration of 4 mg L^-1 on the early life stages of the rainbow trout Oncorhynchus mykiss. The survival rates of O. mykiss were not affected after 36 days of exposure to studied materials, except for RGO, which caused significant mortality of both embryos and larvae compared to the control conditions. Larvae exposed to GO and NFSiC were characterized by a smaller standard body length at hatch, whereas at the end of the experiment, the growth of fish exposed to all materials was accelerated, especially in GO and RGO treatment, in which higher body weight and length were accompanied by lower volume of the yolk sac. Neither the markers of the oxidative damage nor the antioxidant enzymes activities were significantly affected in embryos, newly hatched larvae and larvae after 26-day exposure to studied carbon nanomaterials. Also, no neurotoxic effect expressed by the activity of the whole-body acetylcholinesterase was observed. Nevertheless, the significant increase in the velocity and the overall activity of larvae exposed to GNF (not investigated after exposure to other materials) must be highlighted. The most pronounced effect of RGO might be connected with its large particle size, sharp edges, and the presence of TiO₂ nanoparticles. The results indicate for the first time that various carbon nanomaterials potentially released into aquatic ecosystems may have serious developmental implications for the early life stages of salmonid fish.

Effects of the herbicide ametryn on development and thyroidogenesis of bullfrog tadpoles (Aquarana catesbeiana) under different temperatures

Thyroid hormones (TH) are essential for the metamorphosis of amphibians and their production can be influenced by environmental stressors, such as temperature fluctuations, and exposure to aquatic pollutants, such as herbicides. In the present study we evaluated the influence of different temperatures (25 and 32 °C) on the effects of the herbicide ametryn (AMT, 0 - control, 10, 50 and 200 ng.L^-1) for 16 days on thyroidogenesis of bullfrog tadpoles. Higher temperature and AMT exposure caused a delay in the development of tadpoles, despite no differences were noted in weight gain and total length of the animals. Levels of triiodothyronine (T3) and thyroxine (T4) were not altered neither by AMT nor by temperature, but the highest temperature caused a decrease in total area and number of follicles in the thyroid gland. Transcript levels of thyroid hormone receptors alpha and beta (TRα and TRβ) and iodothyronine deiodinase 3 (DIO3) were lower at 32 °C, which is consistent with developmental delay at the higher temperature. Tadpoles exposed to 200 ng.L^-1 of AMT at 25 °C also presented delayed development, which was consistent with lower TRα and DIO3 transcript levels. Lower levels of estradiol were noted in tadpoles exposed to AMT at the higher temperature, being also possibly related to a developmental delay. This study demonstrates that higher temperature and AMT exposure impair thyroidgenesis in bullfrog tadpoles, disrupting metamorphosis.

Dissolved Organic Matter and Lignin Modulate Aquatic Toxicity and Oxidative Stress Response Activated by Layered Double Hydroxides Nanomaterials

Advanced nanomaterials can be released into the environment and can coexist with natural organic matter (NOM). However, evidence on the impacts of NOM on the environmental behavior and toxicity of advanced nanomaterials is still scarce. Here, we investigated the behavior and toxic effects of two layered double hydroxides (LDHs) nanomaterials with different metallic constituents (Mg-Al-LDH and Zn-Al-LDH) at relatively low exposure concentrations on a freshwater green alga (Chlorella pyrenoidosa) in the absence and presence of two types of NOM, namely dissolved organic matter (DOM) and dealkaline lignin (DL). The DOM or DL interaction with the LDHs at different mixture levels was shown to be an antagonistic effect on the growth inhibition toxicity to C. pyrenoidosa mainly. The estimation of the index of Integrated Biological Responses version 2 indicated that the joint interaction of the LDHs with DOM or DL occurred in the following order of frequency synergism > antagonism > additivity. Furthermore, the physicochemical characteristics of LDHs were crucial for illuminating the mechanism by which the DOM or DL modified the LDH-induced oxidative stress response. These findings highlighted the important role of NOM in the behavior and effect of LDHs as a representative of a new class of multifunctional nanomaterials in the freshwater environment.

Graphene Oxides (GOs) with Different Lateral Dimensions and Thicknesses Affect the Molecular Response in Chironomus riparius

Graphene oxide (GO) materials possess physicochemical properties that facilitate their application in the industrial and medical sectors. The use of graphene may pose a threat to biota, especially aquatic life. In addition, the properties of nanomaterials can differentially affect cell and molecular responses. Therefore, it is essential to study and define the possible genotoxicity of GO materials to aquatic organisms and their ecosystems. In this study, we investigated the changes in the expression of 11 genes in the aquatic organism Chironomus riparius after 96 h of exposure to small GOs (sGO), large GOs (lGO) and monolayer GOs (mlGO) at 50, 500 and 3000 μg/L. Results showed that the different genes encoding heat shock proteins (hsp90, hsp70 and hsp27) were overexpressed after exposure to these nanomaterials. In addition, ATM and NLK-the genes involved in DNA repair mechanisms-were altered at the transcriptional level. DECAY, an apoptotic caspase, was only activated by larger size GO materials, mlGO and lGO. Finally, the gene encoding manganese superoxide dismutase (MnSOD) showed higher expression in the mlG O-treated larvae. The lGO and mlGO treatments indicated high mRNA levels of a developmental gene (FKBP39) and an endocrine pathway-related gene (DRONC). These two genes were only activated by the larger GO materials. The results indicate that larger and thicker GO nanomaterials alter the transcription of genes involved in cellular stress, oxidative stress, DNA damage, apoptosis, endocrine and development in C. riparius. This shows that various cellular processes are modified and affected, providing some of the first evidence for the action mechanisms of GOs in invertebrates. In short, the alterations produced by graphene materials should be further studied to evaluate their effect on the biota to show a more realistic scenario of what is happening at the molecular level.

Effects of Carbon Nanoparticles and Chromium Combined Exposure in Native (Ruditapes decussatus) and Invasive (Ruditapes philippinarum) Clams

Studies have described the occurrence of nanoparticles (NPs) in aquatic ecosystems, with particular attention to the widely commercialized carbon nanotubes (CNTs). Their presence in the environment raises concerns, especially regarding their toxicity when co-occurring with other pollutants such as metals. In the present study, changes to the metabolic capacity, oxidative, and neurologic status were evaluated in the presence of carboxylated multi-walled CNTs and chromium (Cr(III)) using two of the most ecologically and economically relevant filter feeder organisms: the clam species Ruditapes decussatus and R. philippinarum. Results indicated that although Cr, either alone or in combination with CNTs, was found in a similar concentration level in both species, a species-specific Cr accumulation was observed, with higher values in R. decussatus in comparison with R. philippinarum. Inhibition of antioxidant defenses and neurotoxic effects were detected only in R. philippinarum. The interaction between contaminants seems to have no effect in terms of antioxidant enzyme activities and neuro status. Nevertheless, synergistic activation of responses to both contaminants may have altered the metabolic capacity of bivalves, particularly evident in R. decussatus. While both clams are tolerant to both contaminants (alone and together), they showed a relevant accumulation capacity, which may represent a possible contaminant transfer to humans.

Integrated physiological, biochemical, and transcriptomic analysis of thallium toxicity in zebrafish (Danio rerio) larvae

Although several studies have evaluated the effects of Thallium (Tl) in adult species of fish, the developmental toxicity of Tl has not been previously explored. In this study, zebrafish embryos (<4 h post fertilization (hpf)) were exposed to Tl at concentrations from 0.8 to 400 μg L^-1 for 7 d. The results showed that the decreased hatching rate and increased malformation rate were observed in the larvae. The swimming velocity of larvae from 200 and 400 μg L^-1 treatments was respectively reduced by ~26 % and 15 %. Histopathological analysis of liver indicated the number of cells of karyolysis (143 % and 202 %) and pyknosis (170 % and 131 %) were respectively increased in 200 and 400 μg L^-1 Tl treatments. Meanwhile, the Tl body burden and metallothionein (MT) levels in the larvae were increased with elevated Tl concentrations. The level of malondialdehyde (MDA) was increased by ~20 to 51 % in all Tl treatments and total antioxidant capacity (TAC) was decreased by ~12 % at 200 μg L^-1. The activities of Na⁺/K⁺-ATPase and protease were inhibited in 200 and 400 μg L^-1 Tl treatments. Moreover, the transcripts of genes (Nrf2, HO-1, TNF-α, IL-1β, IL-8, IL-10, TGF) were significantly altered. In addition, a total of 930 differentially expressed genes (DEGs) and 1549 DEGs were found in the 200 and 400 μg L^-1 treatments with 458 overlapped DEGs by transcriptomic analysis. The protein digestion and absorption, ECM-receptor interaction, and complement and coagulation cascades pathways were shown to be the most significantly enriched pathways. This study helps better understand the molecular mechanisms of Tl toxicity in fish.

Exploring specific biomarkers regarding neurobehavioral toxicity of lead dioxide nanoparticles in medaka fish in different water matrices

Nano-scale lead dioxide (nPbO₂) is an industrial metal oxide nanoparticle that can be also formed as a corrosion by-product from chlorination of Pb-containing plumbing materials. nPbO₂ governs release of toxic lead ion in drinking water and receiving organisms; however, its modes of toxic action regarding neurobehavioral toxicity remain unclear. This study evaluated the toxicity mechanism of nPbO₂ (10 and 20 mg/L) versus its released Pb(II)_aq (100 μg/L) in terms of aqueous chemistry, bioavailability and neurobehavioral toxicity to medaka fish in different water matrices. In very hard water (VHW), dissolved salts enhanced the aggregation and sedimentation of nPbO₂, resulting in higher bioavailability and altered locomotion of treated fish than those fish exposed to nPbO₂ in soft water with humic acid (SW + HA). Transcriptomic results identified six differentially expressed genes with greater altered expression with nPbO₂ than the control or Pb(II)_aq exposure. With VHW exposure, nPbO₂ caused greater altered expression of genes involved in cell adhesion (nlgn1 and epd), cell cytoskeleton (α1-tubulin), and relevant apoptosis (c-fos, birc5.1-a and casp3), as compared with SW + HA or Pb(II)_aq exposure. This study provides novel molecular mechanistic insights into the neurobehavioral nanotoxicity using nPbO₂ and medaka fish as surrogates, suggesting nPbO₂ promotes neurobehavioral dysfunction, leading to adverse outcomes from gene alteration to the organismal level. The identified biomarkers responded specifically to the nPbO₂-induced neurotoxicity in different water matrices can be used for evaluating toxicity risks of small metal oxide particulates on human or aquatic life under environmentally relevant exposures.

Applicability of OECD TG 201, 202, 203 for the aquatic toxicity testing and assessment of 2D Graphene material nanoforms to meet regulatory needs

Tests using algae and/or cyanobacteria, invertebrates (crustaceans) and fish form the basic elements of an ecotoxicological assessment in a number of regulations, in particular for classification of a substance as hazardous or not to the aquatic environment according to the Globally Harmonised System of Classification and Labelling of Chemicals (GHS-CLP) (GHS, 2022) and the REACH regulation (Registration, Evaluation, Authorisation and Restriction of Chemicals, EC, 2006). Standardised test guidelines (TGs) of the Organisation for Economic Co-operation and Development (OECD) are available to address the regulatory relevant endpoints of growth inhibition in algae and cyanobacteria (TG 201), acute toxicity to invertebrates (TG 202), and acute toxicity in fish (TG 203). Applying these existing OECD TGs for testing two dimensional (2D) graphene nanoforms may require more attention, additional considerations and/or adaptations of the protocols, because graphene materials are often problematic to test due to their unique attributes. In this review a critical analysis of all existing studies and approaches to testing used has been performed in order to comment on the current state of the science on testing and the overall ecotoxicity of 2D graphene materials. Focusing on the specific tests and available guidance's, a complete evaluation of aquatic toxicity testing for hazard classification of 2D graphene materials, as well as the use of alternative tests in an integrated approach to testing and assessment, has been made. This information is essential to ensure future assessments generate meaningful data that will fulfil regulatory requirements for the safe use of this "wonder" material.

Transcriptomic and metabolomic integration to assess the response of gilthead sea bream (Sparus aurata) exposed to the most used insect repellent: DEET

DEET is one of the most frequently detected insect repellents in the environment reaching concentrations of several μg L^-1 in surface water. There is scarce information available regarding its mode of action in non-target organisms. Here, we have used an integrated metabolomic and transcriptomic approach to elucidate the possible adverse effects of DEET exposure in the marine fish gilthead sea bream (Sparus aurata). Individuals were exposed at an environmentally relevant concentration of DEET (10 μg L^-1) for 22 days in a continuous flow-through system. Transcriptomic analysis revealed 250 differentially expressed genes in liver, while metabolomic analysis identified 190 differentially modulated features in liver and 98 in plasma. Multi-omic data integration and visualization allowed elucidation of the modes of action of DEET exposure, including: energy depletion through the disruption of carbohydrate and amino acids metabolisms, oxidative stress leading to DNA damage, lipid peroxidation, and damage to cell membrane and apoptosis. Activation of xenobiotic pathway as well as the inmune-inflammatory reaction was evidenced in the present work.

Graphene oxide disruption of homeostasis and regeneration processes in freshwater planarian Dugesia japonica via intracellular redox deviation and apoptosis

The aquatic system is a major sink for engineered nanomaterials released into the environment. Here, we assessed the toxicity of graphene oxide (GO) using the freshwater planarian Dugesia japonica, an invertebrate model that has been widely used for studying the effects of toxins on tissue regeneration and neuronal development. GO not only impaired the growth of normal (homeostatic) worms, but also inhibited the regeneration processes of regenerating (amputated) worms, with LC₁₀ values of 9.86 mg/L and 9.32 mg/L for the 48-h acute toxicity test, respectively. High concentration (200 mg/L) of GO killed all the worms after 3 (regenerating) or 4 (homeostasis) days of exposure. Whole-mount in situ hybridization (WISH) and immunofluorescence analyses suggest GO impaired stem cell proliferation and differentiation, and subsequently caused cell apoptosis and oxidative DNA damage during planarian regeneration. Mechanistic analysis suggests that GO disturbed the antioxidative system (enzymatic and non-enzymatic) and energy metabolism in the planarian at both molecular and genetic levels, thus causing reactive oxygen species (ROS) over accumulation and oxidative damage, including oxidative DNA damage, loss of mitochondrial membrane integrity, lack of energy supply for cell differentiation and proliferation leading to retardance of neuron regeneration. The intrinsic oxidative potential of GO contributes to the GO-induced toxicity in planarians. These data suggest that GO in aquatic systems can cause oxidative stress and neurotoxicity in planarians. Overall, regenerated tissues are more sensitive to GO toxicity than homeostatic ones, suggesting that careful handling and appropriate decisions are needed in the application of GO to achieve healing and tissue regeneration.

Gene Expression Analysis in gla-Mutant Zebrafish Reveals Enhanced Ca2+ Signaling Similar to Fabry Disease

Fabry disease (FD) is an X-linked inborn metabolic disorder due to partial or complete lysosomal α-galactosidase A deficiency. FD is characterized by progressive renal insufficiency and cardio- and cerebrovascular involvement. Restricted access on Gb3-independent tissue injury experimental models has limited the understanding of FD pathophysiology and delayed the development of new therapies. Accumulating glycosphingolipids, mainly Gb3 and lysoGb3, are Fabry specific markers used in clinical follow up. However, recent studies suggest there is a need for additional markers to monitor FD clinical course or response to treatment. We used a gla-knockout zebrafish (ZF) to investigate alternative biomarkers in Gb3-free-conditions. RNA sequencing was used to identify transcriptomic signatures in kidney tissues discriminating gla-mutant (M) from wild type (WT) ZF. Gene Ontology (GO) and KEGG pathways analysis showed upregulation of immune system activation and downregulation of oxidative phosphorylation pathways in kidneys from M ZF. In addition, upregulation of the Ca²⁺ signaling pathway was also detectable in M ZF kidneys. Importantly, disruption of mitochondrial and lysosome-related pathways observed in M ZF was validated by immunohistochemistry. Thus, this ZF model expands the pathophysiological understanding of FD, the Gb3-independent effects of gla mutations could be used to explore new therapeutic targets for FD.

Graphene oxide decreases the abundance of nitrogen cycling microbes and slows nitrogen transformation in soils

Graphene oxide (GO) has been widely used in many applications due to its excellent properties. Given the extensive production and use of this nanomaterial, its release into the environment is inevitable. However, little is known about the effects of GO on microbial nitrogen transformation and the related processes after GO enters the soil environment. The present study showed that GO significantly reduced soil microbial biomass and caused a decline in microbial diversity after the soils were subjected to various GO concentrations (10, 100, and 1000 mg kg^-1) for 4 months. Among them, the abundances of nitrogen transformation related bacteria such as Firmicutes, Nitrospirota, Proteobacteria, Planctomycetota, and Cyanobacteria were significantly decreased with GO incubation. Among the enzymes that are related to nitrogen transformation, nitrate reductase was the most sensitive even at low concentrations of GO, followed by ammonia monooxygenase and urease, which were reduced by 13-31%, 5-26%, and 9-19% respectively, than those of the control. We found that high concentrations of GO significantly increased the retention of soil urea by 32-59%, and the contents of ammonium and nitrate were 22-28% and 55-69% lower compared to those of the control, respectively. Moreover, the response of most of the indicators in the above process to multilayer GO was more significant than that to single layer GO. Overall, this study provides new insights into the comprehensive understanding of GO's impacts on the soil nitrogen cycle.

The impact of co-treatment with graphene oxide and metal mixture on Salmo trutta at early development stages: The sorption capacity and potential toxicity

Graphene oxide (GO) are novel nanomaterials with a wide range of applications due to their high absorption capacity. This study was undertaken with a view to assess the bioaccumulation and acute toxicity of GO used in combination with the heavy metal mixture (Cr, Cu, Ni and Zn) to fish embryos and larvae. For this purpose, Salmo trutta embryos and larvae were subjected to the 4-day long treatment with three different concentrations of GO, the metal mixture, which was prepared of four metals at the concentrations corresponding to the maximum-permissible-concentrations for EU inland waters (Cr-0.01, Cu-0.01, Ni-0.034, and Zn-0.1 mg/L), and with GO in combination with MIX (GO+MIX). When used in combination with the metal mixture, GO exhibited a high metal sorption capacity. The obtained confocal fluorescence microscopy results showed that GO located in the embryo chorion causing its damage; in larvae, however, GO were found only in the gill region. Results of these experiments confirmed the hypothesis that GO affects the accumulation of metals and mitigates their toxic effects on organism. In embryos, the acute toxicity of exposure to GO and co-exposure to MIX+GO was found to manifest itself through the decreased heart rate (HR) and malondialdehyde (MDA) level and through the increased metallothionein (MT) concentration. Meanwhile, in larvae, GO and MIX+GO were found to induce genotoxicity effects. However, changes in HR, MDA, MT, gill ventilation frequency, yolk sack absorption and cytotoxicity compared with those of the control group were not recorded in larvae. The obtained results confirmed our hypothesis: the combined effect of MIX and GO was less toxic to larvae (especially survival) than individual effects of MIX components. However, our results emphasize that fish exposure to GO alone and in combination with heavy metal contaminants (MIX+GO) even at environmentally relevant concentrations causes health risks that cannot be ignored.

Aging relieves the promotion effects of polyamide microplastics on parental transfer and developmental toxicity of TDCIPP to zebrafish offspring

Understanding the role of microplastics (MPs) in the biological fate and toxicity of organic pollutants in food webs is vital for its risk assessment. However, contradictory results and the neglect of MP aging as a factor have led to a research gap, which needs to be filled. Our study discovered that polyamide (PA, a ubiquitous MP in water) MPs clearly facilitated bioaccumulation of tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) in the F0 zebrafish gonads and parental transfer of TDCIPP to the F1 offspring. Rapid TDCIPP desorption in the gut and intestine barrier dysfunction triggered by MPs were the causes for the phenomenon. In contrast to the pristine forms, aged PA with higher hydrophilcity exhibited stronger binding and polar interactions with TDCIPP, and the intestine damage was neglectable, resulting in increased intestinal immobilization and prevented parental transfer of TDCIPP. Additionally, the aggravated body weight loss and decreased length of TDCIPP offspring were relieved after PA aging. The recovery of subintestinal venous plexus angiogenesis, yolk lipid utilization, and ATP synthesis were responsible for the mitigated transgenerational toxicity. Our results highlight the significance of aging on the role of MPs with respect to coexisting pollutants and have great implications for understanding MP-associated risks.

Ag2Se quantum dots damage the nervous system of nematode Caenorhabditis elegans

Silver selenide quantum dots (Ag₂Se QDs), as a novel type of QDs, are valuable in the biomedical application due to their low-toxic and excellent optical property in near infrared region, but the biosafety assessment of Ag₂Se QDs is rare. In this study, the findings suggested that the accumulation of Ag₂Se QDs in the body of nematodes decreased the lifespan and damaged normal neurobehaviors of Caenorhabditis elegan (C. elegans). Furthermore, Ag₂Se QDs caused excessive reactive oxygen species (ROS) productions and altered expressions of several genes associated with redox equilibrium, which might contribute to neurotoxic outcomes in nematode C. elegans. According to this study, it is necessary and important for researchers to pay attention to the biosafety assessment of presumed low-toxic nanomaterials, like Ag₂Se QDs, especially on sensitively toxic targets, i.e. the nervous system.

Uptake Route Altered the Bioavailability of Graphene in Misgurnus anguillicaudatus: Comparing Waterborne and Sediment Exposures

Numerous studies on the bioavailability of graphene-based nanomaterials relate to the water-only exposure route. However, the sediment exposure route should be the most important pathway for benthic organisms to ingest graphene, while to date little work on the bioavailability of graphene in benthic organisms has been explored. In this study, with the help of carbon-14-labeled few-layer graphene (¹⁴C-FLG), we quantificationally compared the bioaccumulation, biodistribution, and elimination kinetics of ¹⁴C-FLG in loaches via waterborne and sediment exposures. After 72 h of exposure, the accumulated ¹⁴C-FLG in loaches exposed via waterborne was 14.28 μg/g (dry mass), which was 3.18 times higher than that (4.49 μg/g) exposed via sediment. The biodistribution results showed that, compared to waterborne exposure, sediment exposure remarkably facilitated the transport of ¹⁴C-FLG from the gut into the liver, which made it difficult to be excreted. Although ¹⁴C-FLG did not cause significant hepatotoxicity, the disruption of intestinal microbiota homeostasis, immune response, and several key metabolic pathways in the gut were observed, which may be due to the majority of ¹⁴C-FLG being accumulated in the gut. Overall, this study reveals the different bioavailabilities of graphene in loaches via waterborne and sediment exposures, which is helpful in predicting its bioaccumulation capability and trophic transfer ability.

Nanosafety Analysis of Graphene-Based Polyester Resin Composites on a Life Cycle Perspective

The use, production, and disposal of engineering nanomaterials (ENMs), including graphene-related materials (GRMs), raise concerns and questions about possible adverse effects on human health and the environment, considering the lack of harmonized toxicological data on ENMs and the ability of these materials to be released into the air, soil, or water during common industrial processes and/or accidental events. Within this context, the potential release of graphene particles, their agglomerates, and aggregates (NOAA) as a result of sanding of a battery of graphene-based polyester resin composite samples intended to be used in a building was examined. The analyzed samples were exposed to different weathering conditions to evaluate the influence of the weathering process on the morphology and size distribution of the particles released. Sanding studies were conducted in a tailored designed sanding bench connected to time and size resolving measurement devices. Particle size distributions and particle number concentration were assessed using an optical particle counter (OPC) and a condensation particle counter (CPC), respectively, during the sanding operation. A scanning electron microscope/energy dispersive X-ray (SEM/EDX) analysis was performed to adequately characterize the morphology, size, and chemical composition of the released particles. A toxicity screening study of pristine and graphene-based nanocomposites released using the aquatic macroinvertebrate Daphnia magna and relevant human cell lines was conducted to support risk assessment and decision making. The results show a significant release of nanoscale materials during machining operations, including differences attributed to the % of graphene and weathering conditions. The cell line tests demonstrated a higher effect in the human colon carcinoma cell line Caco2 than in the human fibroblasts (A549 cell line), which means that composites released to the environment could have an impact on human health and biota.

Graphene oxide chronic exposure enhanced perfluorooctane sulfonate mediated toxicity through oxidative stress generation in freshwater clam Corbicula fluminea

Graphene oxide (GO), a frequently utilized graphene family nanomaterial, is inevitably released into the aquatic environment and interacts with organic pollutants, including perfluorooctane sulfonate (PFOS), a well-known persistent organic pollutant. To determine the adverse effects of GO chronic exposure on PFOS bioaccumulation and toxicity, adult freshwater bivalves, namely Asian clams (Corbicula fluminea) were treated for 28 days with PFOS (500 ng/L) and different concentrations of GO (0.2, 1, 5 mg/L) as PFOS single and GO single exposure groups, as well as PFOS-GO mixture exposure groups. Our results demonstrated that the bioaccumulation of PFOS was significantly enhanced by co-exposure in gills and visceral masses, which was 1.64-2.91 times higher in gills than in visceral masses. Both single, as well as co-exposure, caused a significant reduction in clams' siphoning behavior, compared to the controls. Further, the co-exposure significantly increased the production of reactive oxygen species (ROS), exacerbating malondialdehyde (MDA) content, enhancing superoxide dismutase (SOD) and catalase (CAT), while decreasing glutathione reductase (GR) and glutathione S-transferase (GST) enzymatic activities in clam tissues. And co-exposure significantly altered the expressions of se-gpx, sod, cyp30, hsp40, and hsp22 genes (associated with oxidative stress and xenobiotic metabolism) both in gills and visceral masses. Moreover, co-exposure caused significant histopathological changes such as cilia degradation in the gills, expansion of tubule lumens in digestive glands, and oocyte shrinkage in gonads. Finally, the enhanced integrated biomarker response (EIBR) index revealed that co-exposure to 500 ng/L PFOS + 1 mg/L/5 mg/L GO was the most stressful circumstance. Overall, our findings suggested that the presence of GO increased PFOS bioaccumulation in tissues, inducing multifaceted negative implications at molecular and behavioral levels through oxidative stress generation in Asian clams.

Effects of graphene oxide nanosheets in the polychaete Hediste diversicolor: Behavioural, physiological and biochemical responses

Numerous applications exist for graphene-based materials, such as graphene oxide (GO) nanosheets. Increased concentrations of GO nanosheets in the environment have the potential to have a large negative effect on the aquatic environment, with consequences for benthic organisms, such as polychaetes. The polychaete Hediste diversicolor mobilises the sediments, hence altering the availability of contaminants and the nutrients biogeochemical cycle. As such, this study proposes to assess the effects of different GO nanosheet concentrations on the behaviour, feeding activity, mucus production, regenerative capacity, antioxidant status, biochemical damage and metabolism of H. diversicolor. This study evidenced that H. diversicolor exposed to GO nanosheets had a significantly lower ability to regenerate their bodies, took longer to feed and burrow into the sediment and produced more mucus. Membrane oxidative damage (lipid peroxidation) increased in exposed specimens. The increased metabolic rate (ETS) evidenced a higher energy expenditure in exposed organisms (high use of ready energy sources - soluble sugars) to fight the toxicity induced by GO nanosheets, such as SOD activity. The increase in SOD activity was enough to reduce reactive oxygen species (ROS) induced by GO on cytosol at the lowest concentrations, avoiding the damage on proteins (lower PC levels), but not on membranes (LPO increase). This study revealed that the presence of GO nanosheets, even at the lower levels tested, impaired behavioural, physiological, and biochemical traits in polychaetes, suggesting that the increase of this engineered nanomaterial in the environment can disturb these benthic organisms, affecting the H. diversicolor population. Moreover, given the important role of this group of organisms in coastal and estuarine food webs, the biogeochemical cycle of nutrients, and sediment oxygenation, there is a real possibility for repercussions into the estuarine community.

Co-exposure of zinc oxide nanoparticles and multi-layer graphenes in blackfish (Capoeta fusca): evaluation of lethal, behavioural, and histopathological effects

Zinc oxide nanoparticles (ZnO NPs) and multi-layer graphenes (MLGs) are widely used, and due to the lack of appropriate wastewater treatment may end up in the aquatic environment, with unknown consequences to biota. The main purpose of this study was to assess the acute toxicity, histopathological and behavioural changes caused by the exposure of ZnO NPs and MLGs, alone and combined, to the blackfish Capoeta fusca. The estimated mean 96 h-LC₅₀ for ZnO NPs was 4.9 mg L^-1 and 68.4 mg L^-1 for MLGs. In combination, MLGs increased the acute toxicity of the ZnO NPs. The effects of the different NPs on the gills included hyperplasia, aneurisms, and fusion of the lamellae. In the intestine, exposure to the NPs resulted in an increase in the number and swelling of goblet cells and tissue degeneration. Loss of balance, restlessness, erratic and abnormal swimming patterns were the most common behavioural changes seen in the ZnO NPs' exposed blackfish. In contrast with the acute toxicity findings, MLGs decreased the histopathological and behavioural effects of the ZnO NPs on both gills and intestinal tissues as well as fish behaviour. Our experimental results illustrated insights into the simultaneous exposure assessment of metal-based NPs and carbon nanomaterials, although further research is needed on the interactions exposure of these substances to interpreting the toxicological effects of metal-based nanomaterials seen in exposed organisms.

Size- and Oxidation-Dependent Toxicity of Graphene Oxide Nanomaterials in Embryonic Zebrafish

Graphene oxides (GOs) are a popular graphene alternative. The goal of this study was to compare the biocompatibility of a diversity of well-characterized GOs. Our previous work advanced developmental zebrafish as a model to interrogate the interactions and biological responses following exposures to engineered nanomaterials (ENMs). Here, we investigated GO 250 nm × 250 nm (sGO), 400 nm × 400 nm (mGO), and 1 μm × 1 μm (lGO), partially reduced GO (prGO) 400 nm × 400 nm, and reduced GO (rGO) 400 nm × 400 nm and 2 μm × 2 μm, which first underwent extensive characterization under the support of the Nanomaterials Health Implications Research (NHIR) Consortium. GOs were stabilized in water (GOs), while prGO and rGOs were dispersed in sodium cholate. Zebrafish were statically exposed to up to 50 μg/mL of each material from 6 h post-fertilization (hpf) until 120 hpf. Toxicity was dependent on GO properties. mGO was the most toxic material; its effects manifested in the yolk syncytial layer (YSL). Additionally, sodium cholate stabilization significantly increased GO toxicity. The observed effects were size- and oxidation-state-dependent, revealing the importance of identifying the structure-specific toxicity of GOs.

Comparative evaluation of the mechanisms of toxicity of graphene oxide and graphene oxide quantum dots to blue-green algae Microcystis aeruginosa in the aquatic environment

Due to the diverse applications, graphene-family nanomaterials (GFNs) have a high probability of release into the aquatic system, potentially posing risks to the aquatic environment. The acute effects on single-celled Microcystis aeruginosa by graphene oxide (GO) or graphene oxide quantum dots (GOQDs) were compared in the present study. GOQDs dispersed more effectively in water than GO at all pH values tested. The 96-hour median effective concentration (EC₅₀) of GO and GOQDs were determined to be 49.32 and 22.46 mg/L, respectively. Both GO and GOQDs were internalized by heteroagglomeration and envelopment processes, with GOQDs inducing stronger upregulation of cell permeability, plasmolysis and lipid bodies than GO. Cracking of thylakoid layers, disappearance of nucleoid, and disintegration of cell infrastructure were observed at higher concentrations. In comparison to GO, GOQDs induced higher reactive oxygen species (ROS) and malondialdehyde (MDA) and disrupted antioxidant enzymes, leading to the inhibition of cellular contents such as chlorophyll a and proteins. Furthermore, both GO and GOQDs adsorbed nutrients from the algal medium, resulting in nutrient depletion-induced indirect toxicity, with GOQDs depleting more nutrients than GO. The current study provides new understanding of nanotoxicity of GO and GOQD and aids in the potential risks of nanomaterials in aquatic environments.

Graphene oxide enhanced the endocrine disrupting effects of bisphenol A in adult male zebrafish: Integrated deep learning and metabolomics studies

In our previous studies, it was found that graphene oxide (GO) reduced the endocrine disruption of bisphenol A (BPA) in zebrafish embryo and larvae, but through different mechanisms. In this study, adult male zebrafish were selected to further understand the interactions between GO and BPA considering that adult zebrafish have different uptake pathways and metabolism from embryo and larvae. BPA was predicted to bind with the estrogen receptor α (ERα) with a probability of 98.1% by training a directed-message passing deep neural network model, and was confirmed by molecular docking analysis. The results were in accordance with the significantly increased vitellogenin (VTG) and estradiol (E2) levels, while decreased testosterone (T) and follicle-stimulating hormone (FSH) levels in the adult male zebrafish after 7 d exposure to 500 μg/L BPA. Compared to BPA single exposure group, the presence of GO led to significantly lower T and FSH levels and fewer spermatozoa, indicating that GO enhanced the endocrine disruption effects of BPA in the adult zebrafish. Metabolomics analysis revealed that 5 μg/L BPA could elicit changes in the metabolome, and the responses were correlated with BPA concentrations. Metabolic pathway analysis revealed more disturbance was caused by the mixture of GO and BPA compared to BPA alone, including three additional pathways and stronger perturbations on carbohydrate, lipid, and amino acid metabolism, fortifying that GO exaggerated the toxic effects of BPA. This was opposite to the depression effect observed in zebrafish embryo and larvae, magnifying that the joint effects of exposure to nanomaterials and endocrine disrupting chemicals are relevant to the life stages of organisms.

CRISPR/Cas9-Mediated Targeted Mutagenesis of GmUGT Enhanced Soybean Resistance Against Leaf-Chewing Insects Through Flavonoids Biosynthesis

Leaf-chewing insects are important pests that cause yield loss and reduce seed quality in soybeans (Glycine max). Breeding soybean varieties that are resistant to leaf-chewing insects can minimize the need for insecticide use and reduce yield loss. The marker gene for QTL-M, Glyma.07g110300 (LOC100775351) that encodes a UDP-glycosyltransferase (UGT) is the major determinant of resistance against leaf-chewing insects in soybean; it exhibits a loss of function in insect-resistant soybean germplasms. In this study, Agrobacterium-mediated transformation introduced the CRISPR/Cas9 expression vector into the soybean cultivar Tianlong No. 1 to generate Glyma.07g110300-gene mutants. We obtained two novel types of mutations, a 33-bp deletion and a single-bp insertion in the GmUGT coding region, which resulted in an enhanced resistance to Helicoverpa armigera and Spodoptera litura. Additionally, overexpressing GmUGT produced soybean varieties that were more sensitive to H. armigera and S. litura. Both mutant and overexpressing lines exhibited no obvious phenotypic changes. The difference in metabolites and gene expression suggested that GmUGT is involved in imparting resistance to leaf-chewing insects by altering the flavonoid content and expression patterns of genes related to flavonoid biosynthesis and defense. Furthermore, ectopic expression of the GmUGT gene in the ugt72b1 mutant of Arabidopsis substantially rescued the phenotype of H. armigera resistance in the atugt72b1 mutant. Our study presents a strategy for increasing resistance against leaf-chewing insects in soybean through CRISPR/Cas9-mediated targeted mutagenesis of the UGT genes.

Environmental decomposition and remodeled phytotoxicity of framework-based nanomaterials

Zeolitic imidazole frameworks (ZIFs) have attracted a considerable amount of attention for use in environmental applications (e.g., pollutant adsorption and photocatalysis in water treatments). The environmental stability and toxicity of ZIFs are key prerequisites for their practical applications, but information about these factors is largely lacking. The present work finds that pristine ZIFs (ZIF-8 and ZIF-67) photodegrade from frame structures into two-dimensional nanosheets and are oxidized to zinc carbonate (ZIF-8) and Co₃O₄ (ZIF-67) under visible-light irradiation. The photoinduced electrons, holes and free radicals promote dissolution of the metal cores and organic ligands, leading to collapse of the frame structure. The photodegradation of ZIF-8 alleviates developmental inhibition, oxidative stress, plasmolysis, and photosynthetic toxicity, while the photodegradation of ZIF-67 aggravates nanotoxicity. The integration of metabolomics and transcriptomics analysis reveals that unsaturated fatty acid biosynthesis and metal ion-binding transcription contribute to the altered toxicity of ZIF photodegradation. These findings highlight the roles of photodegradation in structural transformation and alteration of the toxicity of ZIFs, alarming the study of pristine metal-organic frameworks (MOFs).

Sublethal toxicity of graphene oxide in Caenorhabditis elegans under multi-generational exposure

Nanomaterials have received increasing attentions owing to their potential hazards to the environment and human health; however, the multi-generational toxicity of graphene oxide under consecutive multi-generational exposure scenario still remains unclear. In the present study, Caenorhabditis elegans as an in vivo model organism was employed to explore the multi-generational toxicity effects of graphene oxide and the underlying mechanisms. Endpoints including development and lifespan, locomotion behaviors, defecation cycle, brood sizes, and oxidative response were evaluated in the parental generation and subsequent five filial generations. After continuous exposure for several generations, worms grew smaller and lived shorter. The locomotion behaviors were reduced across the filial generations and these reduced trends were following the impairments of locomotion-related neurons. In addition, the extended defecation cycles from the third filial generation were in consistency with the relative size reduction of the defecation related neuron. Simultaneously, the fertility function of the nematode was impaired under consecutive exposure as reduced brood sizes and oocytes numbers, increased apoptosis of germline, and aberrant expression of reproductive related genes ced-3, ced-4, ced-9, egl-1 and ced-13 were detected in exposed worms. Furthermore, the antioxidant enzyme, SOD-3 was significantly increased in the parent and filial generations. Thus, continuous multi-generational exposure to graphene oxide caused damage to the neuron development and the reproductive system in nematodes. These toxic effects could be reflected by indicators such as growth inhibition, shortened lifespan, and locomotion behavior impairment and induced oxidative response.

Graphene oxide promoted chromium uptake by zebrafish embryos with multiple effects: Adsorption, bioenergetic flux and metabolism

The increasing production and application of graphene oxide (GO, a popular carbon nanomaterial), makes their release into aqueous environment inevitably. The capability of GO to enhance the toxicity of background contaminants has been widely concerned. However, the effect of GO on heavy metal accumulation in fish embryos remains unclear. Here, we show that GO-promoted chromium (Cr) uptake by zebrafish embryos with multiple effects. The adsorption accelerated the aggregation and settlement of Cr⁶⁺-adsorbed GO and decreased the Cr⁶⁺ concentration in the upper water, which enhanced the interaction of chorions and contaminants (Cr⁶⁺, GO and Cr⁶⁺-adsorbed GO). In the presence of GO, the Cr content in chorions and intra-chorion embryos was increased by four times and 57% respectively, compared to that of the single Cr⁶⁺ exposure. Furthermore, GO+Cr⁶⁺ increased the oxygen consumption rates, embryonic acid extrusion rates and ATP production, induced more serious oxidative stress, and disturbed amino acid metabolism, fatty acid metabolism and TCA cycle. These findings provide new insights into the effect of GO on heavy metal bioaccumulation and toxicity during embryogenesis.