Parental CuO nanoparticles exposure results in transgenerational toxicity in Caenorhabditis elegans associated with possible epigenetic regulation

Effects of dissolved organic matter on the environmental behavior and toxicity of metal nanomaterials: A review

Metal nanomaterials (MNMs) have been released into the environment during their usage in various products, and their environmental behaviors directly impact their toxicity. Numerous environmental factors potentially affect the behaviors and toxicity of MNMs with dissolved organic matter (DOM) playing the most essential role. Abundant facts showing contradictory results about the effects of DOM on MNMs, herein the occurrence of DOM on the environmental process change of MNMs such as dissolution, dispersion, aggregation, and surface transformation were summarized. We also reviewed the effects of MNMs on organisms and their mechanisms in the environment such as acute toxicity, oxidative stress, oxidative damage, growth inhibition, photosynthesis, reproductive toxicity, and malformation. The presence of DOM had the potential to reduce or enhance the toxicity of MNMs by altering the reactive oxygen species (ROS) generation, dissolution, stability, and electrostatic repulsion of MNMs. Furthermore, we summarized the factors that affected different toxicity including specific organisms, DOM concentration, DOM types, light conditions, detection time, and production methods of MNMs. However, the more detailed mechanism of interaction between DOM and MNMs needs further investigation.

Transgenerational toxicity induced by maternal AFB1 exposure in Caenorhabditis elegans associated with underlying epigenetic regulations

Aflatoxin B1 (AFB1), usually seriously contaminates in grain and oil foods or feed, displayed significant acute and chronic toxic effects in human and animal populations. However, little is known about the transgenerational toxic effects induced by a maternal AFB1 intake at a lower dose on offspring. In our study, only parental wild-type Caenorhabditis elegans was exposed to AFB1 (0-8 μg/ml) and the following three filial generations were grown on AFB1-free NGM. Results showed that the toxic effects of AFB1 on the growth (body length) and reproduction (brood size, generation time and morphology of gonad arm) can be transmitted through generations. Moreover, the levels of MMP and ATP were irreversibly inhibited in the filial generations. By using RNomics and molecular biology techniques, we found that steroid biosynthesis, phagosome, valine/leucine/isoleucine biosynthesis and oxidative phosphorylation (p < 0.05) were the core signaling pathways to exert the transgenerational toxic effects on nematodes. Also, notably increased histone methylation level at H3K36me3 was observed in the first generation. Taken together, our study demonstrated that AFB1 has notable transgenerational toxic effects, which were resulted from the complex regulatory network of various miRNAs, mRNAs and epigenetic modification in C. elegans.

Photoaged Polystyrene Nanoplastics Result in Transgenerational Reproductive Toxicity Associated with the Methylation of Histone H3K4 and H3K9 in Caenorhabditis elegans

Polystyrene nanoplastics (PS-NPs) are emerging environmental contaminants that are ubiquitously detected in various environments and have toxic effects on various organisms. Nevertheless, the transgenerational reproductive toxicity and underlying mechanisms of PS-NPs remain largely unknown, especially for photoaged PS-NPs under ultraviolet irradiation. In this study, only the parental generation (P0) was exposed to virgin and aged PS-NPs at environmentally relevant concentrations (0.1-100 μg/L), and subsequent generations (F1-F4) were cultured under normal conditions. Ultraviolet irradiation induced the generation of environmentally persistent free radicals and reactive oxygen species, which altered the physical and chemical characteristics of PS-NPs. The results of toxicity testing suggested that exposure to aged PS-NPs caused a more severe decrease in brood size, egg ejection rate, number of fertilized eggs, and hatchability than did the virgin PS-NPs in the P0, F1, and F2 generations. Additionally, a single maternal exposure to aged PS-NPs resulted in transgenerational effects on fertility in the F1 and F2 generations. Increased levels of H3K4 and H3K9 methylation were observed in the F1 and F2 generations, which were concomitant with the transgenerational downregulation of the expression of associated genes, such as spr-5, set-17, and met-2. On the basis of correlation analyses, the levels of histone methylation and the expression of these genes were significantly correlated to transgenerational reproductive effects. Further research showed that transgenerational effects on fertility were not observed in spr-5(by134), met-2(n4256), and set-17(n5017) mutants. Overall, maternal exposure to aged PS-NPs induced transgenerational reproductive effects via H3K4 and H3K9 methylation, and the spr-5, met-2, and set-17 genes were involved in the regulation of transgenerational toxicity. This study provides new insights into the potential risks of photoaging PS-NPs in the environment.

Nanoparticles-induced potential toxicity on human health: Applications, toxicity mechanisms, and evaluation models

Nanoparticles (NPs) have become one of the most popular objects of scientific study during the past decades. However, despite wealth of study reports, still there is a gap, particularly in health toxicology studies, underlying mechanisms, and related evaluation models to deeply understanding the NPs risk effects. In this review, we first present a comprehensive landscape of the applications of NPs on health, especially addressing the role of NPs in medical diagnosis, therapy. Then, the toxicity of NPs on health systems is introduced. We describe in detail the effects of NPs on various systems, including respiratory, nervous, endocrine, immune, and reproductive systems, and the carcinogenicity of NPs. Furthermore, we unravels the underlying mechanisms of NPs including ROS accumulation, mitochondrial damage, inflammatory reaction, apoptosis, DNA damage, cell cycle, and epigenetic regulation. In addition, the classical study models such as cell lines and mice and the emerging models such as 3D organoids used for evaluating the toxicity or scientific study are both introduced. Overall, this review presents a critical summary and evaluation of the state of understanding of NPs, giving readers more better understanding of the NPs toxicology to remedy key gaps in knowledge and techniques.

Multi-generation reproductive toxicity of RDX and the involved signal pathways in Caenorhabditis elegans

As one of the most frequently used explosives, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) can cause persistent pollution in the environment, leading to the potential ecological threat crossing the generations. In this study, we employed Caenorhabditis elegans to explore the toxic effects of RDX on the parental and offspring worms and the involved signaling pathways. Exposure up to 1000 ng/mL of RDX produced a significant increase in reactive oxygen species (ROS) production, germ cell apoptosis, and decrease in eggs laid. Various mutants were used to demonstrate the RDX-induced apoptosis signaling pathway, and the metabolism of RDX in the nematodes was found related to cytochrome P450 and GST through RNA sequencing. Exposure of parental worms to RDX produced significant reproductive toxicity in F1 and F2, but was recovered in F3 and F4. The transgenerational effects were associated with the decreased expression of met-2, spr-5, and set-2. Our findings revealed the signaling pathways related to the reproductive toxicity caused by RDX in C. elegans and their future generations, which provided the basis for further exploration of the ecological risks of energetic compounds in the environment.

The co-occurrent microplastics and nano-CuO showed antagonistic inhibitory effects on bacterial denitrification: Interaction of pollutants and regulations on functional genes

The wide occurrence of microplastics (MPs) and nanoparticles resulted in their inevitable coexistence in environment. However, the joint effects of these two types of particulate emerging contaminants on denitrification have seldomly been investigated. Herein, non-biodegradable polyvinyl chloride, polypropylene, polyethylene and biodegradable polyhydroxyalkanoate (PHA) MPs were chosen to perform the co-occurrent effects with nano copper oxide (nano-CuO). Both the nano-CuO and MPs inhibited the denitrification process, and biodegradable PHA-MPs showed severer inhibition than non-biodegradable MPs. However, the presence of MPs significantly alleviated the inhibition of nano-CuO, suggesting an antagonistic effect. Other than MPs decreasing copper ion release from nano-CuO, MPs and nano-CuO formed agglomerations and induced lower levels of oxidative stress compared to individual exposure. Transcriptome analysis indicated that the co-occurrent MPs and nano-CuO induced different regulation on denitrifying genes (e. g. nar and nor) compared to individual ones. Also, the expressions of genes involved in denitrification-associated metabolic pathways, including glycolysis and NADH electron transfer, were down-regulated by nano-CuO or MPs, but exhibiting recovery under the co-occurrent conditions. This study firstly discloses the antagonistic effect of nano-CuO and MPs on environmental process, and these findings will benefit the systematic evaluation of MPs environmental behavior and co-occurrent risk with other pollutants.

Caenorhabditis elegans as a Prediction Platform for Nanotechnology-Based Strategies: Insights on Analytical Challenges

Nanotechnology-based strategies have played a pivotal role in innovative products in different technological fields, including medicine, agriculture, and engineering. The redesign of the nanometric scale has improved drug targeting and delivery, diagnosis, water treatment, and analytical methods. Although efficiency brings benefits, toxicity in organisms and the environment is a concern, particularly in light of global climate change and plastic disposal in the environment. Therefore, to measure such effects, alternative models enable the assessment of impacts on both functional properties and toxicity. Caenorhabditis elegans is a nematode model that poses valuable advantages such as transparency, sensibility in responding to exogenous compounds, fast response to perturbations besides the possibility to replicate human disease through transgenics. Herein, we discuss the applications of C. elegans to nanomaterial safety and efficacy evaluations from one health perspective. We also highlight the directions for developing appropriate techniques to safely adopt magnetic and organic nanoparticles, and carbon nanosystems. A description was given of the specifics of targeting and treatment, especially for health purposes. Finally, we discuss C. elegans potential for studying the impacts caused by nanopesticides and nanoplastics as emerging contaminants, pointing out gaps in environmental studies related to toxicity, analytical methods, and future directions.

Chronic and transgenerational effects of silver nanoparticles in freshwater gastropod Lymnaea stagnalis

Traditional ecotoxicological studies prove to be focused mainly on single-generation, multigenerational research in ecotoxicological testing is needed to improve the predictive approaches in ecological risk assessment. Silver nanoparticles (AgNPs) have been increasingly detected in aquatic environments due to their extensive use in consumer products. We investigated the transgenerational effects of AgNPs on the life traits of freshwater model gastropods Lymnaea stagnalis for two generations. The reversibility of the effects of using recovery experiments was also performed. Results showed that AgNPs induced high Ag bioaccumulation in the whole soft tissues of parental L. stagnalis after 21 days of exposure. The increased ROS production and reduced condition index and fecundity were found after exposure to AgNPs at 500 μg/L. These results highlight that under AgNPs exposure, adult gastropods might allocate more resources to resist oxidative stress rather than to growth or reproduction. Furthermore, the Ag accumulation and ROS production of egg clutches were significantly related to parental exposure duration and concentrations. On the other hand, isolated eggs exposure demonstrated biological effects were persistent in terms of the next generation. For example, after transfer to a clean medium, similar Ag bioaccumulation and ROS production were observed from eggs which parents were pre-exposed to 50 and 500 μg/L AgNPs. Current explicit consideration of offspring performance adds value to existing toxicity testing protocols. Parental exposure duration has important implications for offspring effects, and parental exposure can cause transgenerational changes in resistance that have significant implications for toxicity testing and adaptive responses. These effects across generations point out the need for multigenerational tests to assess the environmental risk of MNPs in aquatic organisms.

Fosthiazate exposure induces oxidative stress, nerve damage, and reproductive disorders in nontarget nematodes

As a forceful nematicide, fosthiazate has been largely applied in the management of root-knot nematodes and other herbivorous nematodes. However, the toxicity of fosthiazate to nontarget nematodes is unclear. To explore the toxicity and the mechanisms of fosthiazate in nontarget nematodes, Caenorhabditis elegans was exposed to 0.01-10 mg/L fosthiazate. The results implied that treatment with fosthiazate at doses above 0.01 mg/L could cause injury to the growth, locomotion behavior, and reproduction of the nematodes. Moreover, L1 larvae were more vulnerable to fosthiazate exposure than L4 larvae. Reactive oxygen species (ROS) production and lipofuscin accumulation were fairly increased in 1 mg/L fosthiazate-exposed nematodes. Treatment with 0.1 mg/L fosthiazate significantly inhibited the activity of acetylcholinesterase (p < 0.01). Furthermore, subacute exposure to 10 mg/L fosthiazate strongly influenced the expression of genes related to oxidative stress, reproduction, and nerve function (e.g., gst-1, sod-1, puf-8, wee-1.3, and ace-1 genes). These findings suggested that oxidative stress, reproduction and nerve disorders could serve as key endpoints of toxicity induced by fosthiazate. The cyp-35a family gene was the main metabolic fosthiazate in C. elegans, and the cyp-35a5 subtype was the most sensitive, with a change in expression level of 2.11-fold compared with the control. These results indicate that oxidative stress and neurological and reproductive disorders played fundamental roles in the toxicity of fosthiazate in C. elegans and may affect the abundance and function of soil nematodes.

A review of transgenerational and multigenerational toxicology in the in vivo model animal Caenorhabditis elegans

A large number of pollutants existing in the environment can last for a long time, and their potential toxic effects can transfer from parents to their offspring. Thus, it is necessary to investigate the toxicity of environmental pollutants across multigenerations and the underlying mechanisms in organisms. Due to its short life cycle and sensitivity to environmental exposures, Caenorhabditis elegans is an important animal model for toxicity assessment of environmental pollutants across multigenerations. In this review, we introduced the transgenerational and multigenerational toxicity caused by various environmental pollutants in C. elegans. Moreover, we discussed the underlying mechanisms for the observed transgenerational and multigenerational toxicity of environmental contaminants in C. elegans.

DNA methylation 6 mA and histone methylation involved in multi-/trans-generational reproductive effects in Caenorhabditis elegans induced by Atrazine

Atrazine (ATR), a widely used triazine herbicide, is an environmental endocrine disruptor that can cause health problems. However, whether there are multi/trans-generational reproductive impacts of ATR have not been studied. Therefore, in this study, Caenorhabditis elegans was used as a preferable model organism to identify the multi/trans-generational reproductive toxicity of ATR. Only parental C.elegans (P0) were exposed to different concentrations (0.0004-40 mg/L) for 48 h and the subsequent offspring (F1-F5) were grown under ATR-free conditions and ATR conditions.The results showed that ATR exposure during P0 decreased fecundity, including a reduction in fertilized eggs, oocytes, and ovulation rate, delayed gonadal development, and decreased the relative area of gonad arm and germ cell number. Furthermore, continuous ATR exposure (P0-F5) causes a significant increase in reproductive toxicity in subsequent generations, although no significant toxicity occurred in the P0 generation after exposure to environmental-related concentrations, suggesting that ATR exposure might have cumulative effects. Likewise, parental exposure to ATR caused transgenerational toxicity impairments. Interestingly, only reproductive toxicity, not development toxicity, was transmitted to several generations (F1-F4), and the F2 generation showed the most notable changes. QRT-PCR results showed that genes expression related to DNA methylation 6 mA (damt-1, nmad-1) and histone H3 methylation (mes-4, met-2, set-25, set-2, and utx-1) can also be passed on to offspring. The function of H3K4 and H3K9 methylation were explored by using loss-of-function mutants for set-2, set-25, and met-2. Transmissible reproductive toxicity was absent in met-2(n4256), set-2(ok952), and set-25(n5021) mutants, which suggests that the histone methyltransferases H3K4 and H3K9 activity are indispensable for the transgenerational effect of ATR. Finally, the downstream genes of DNA methylation and histone H3 methylation were determined. ATR upregulated the expression of ZC317.7, hsp-6, and hsp-60. Mitochondrial stress in parental generation dependent transcription 6 mA modifiers may establish these epigenetic marks in progeny.

Nanoplastic Exposure at Predicted Environmental Concentrations Induces Activation of Germline Ephrin Signal Associated with Toxicity Formation in the Caenorhabditis elegans Offspring

In nematode Caenorhabditis elegans, exposure to polystyrene nanoparticles (PS-NPs) at predicted environmental concentrations can cause induction of transgenerational toxicity. However, the underlying mechanisms for toxicity formation of PS-NP in the offspring remain largely unknown. In this study, based on high-throughput sequencing, Ephrin ligand EFN-3 was identified as a target of KSR-1/2 (two kinase suppressors of Ras) in the germline during the control of transgenerational PS-NP toxicity. At parental generation (P0-G), exposure to 0.1-10 μg/L PS-NP caused the increase in expression of germline efn-3, and this increase in germline efn-3 expression could be further detected in the offspring, such as F1-G and F2-G. Germline RNAi of efn-3 caused a resistance to transgenerational PS-NP toxicity, suggesting that the activation of germline EFN-3 at P0-G mediated transgenerational PS-NP toxicity. In the offspring, Ephrin receptor VAB-1 was further activated by the increased EFN-3 caused by PS-NP exposure at P0-G, and RNAi of vab-1 also resulted in resistance to transgenerational PS-NP toxicity. VAB-1 acted in both the neurons and the germline to control toxicity of PS-NP in the offspring. In the neurons, VAB-1 regulated PS-NP toxicity by suppressing expressions of DBL-1, JNK-1, MPK-1, and GLB-10. In the germline, VAB-1 regulated PS-NP toxicity by increasing NDK-1 and LIN-23 expressions and decreasing EGL-1 expression. Therefore, germline Ephrin ligand EFN-3 and its receptor VAB-1 acted together to mediate the formation of transgenerational PS-NP toxicity. Our data highlight the important role of activation in germline Ephrin signals in mediating transgenerational toxicity of nanoplastics at predicted environmental concentrations in organisms.

Review of the toxicity and potential molecular mechanisms of parental or successive exposure to environmental pollutants in the model organism Caenorhabditis elegans

Environmental pollutants such as heavy metals, nano/microparticles, and organic compounds have been detected in a wide range of environmental media, causing long-term exposure in various organisms and even humans through breathing, contacting, ingestion, and other routes. Long-term exposure to environmental pollutants in organisms or humans promotes exposure of offspring to parental and environmental pollutants, and subsequently results in multiple biological defects in the offspring. This review dialectically summarizes and discusses the existing studies using Caenorhabditis elegans (C. elegans) as a model organism to explore the multi/transgenerational toxicity and potential underlying molecular mechanisms induced by environmental pollutants following parental or successive exposure patterns. Parental and successive exposure to environmental pollutants induces various biological defects in C. elegans across multiple generations, including multi/transgenerational developmental toxicity, neurotoxicity, reproductive toxicity, and metabolic disturbances, which may be transmitted to progeny through reactive oxygen species-induced damage, epigenetic mechanisms, insulin/insulin-like growth factor-1 signaling pathway. This review aims to arouse researchers' interest in the multi/transgenerational toxicity of pollutants and hopes to explore the possible long-term effects of environmental pollutants on organisms and even humans, as well as to provide constructive suggestions for the safety and management of emerging alternatives.

Alteration in Wnt signaling mediates induction of transgenerational toxicity of polystyrene nanoplastics in C. elegans

Polystyrene nanoparticles (PS-NPs) have a potential toxicity on offspring after the exposure. However, the molecular basis for PS-NP in inducing transgenerational toxicity remains largely unknown. In this study, the role and the underlying mechanism of germline Wnt signaling in regulating transgenerational toxicity of PS-NPs were determined using an in vivo animal model of Caenorhabditis elegans. Exposure to PS-NP (1-100 μg/L) increased expression of Wnt ligand LIN-44 and decreased expression of Wnt receptor MIG-1. After the exposure, the transgenerational PS-NP toxicity on locomotion behavior and brood size were inhibited in lin-44(RNAi) nematodes, while enhanced in mig-1(RNAi) nematodes. The resistance to transgenerational PS-NP toxicity induced by RNAi of lin-44 in P0 generation (P0-G) was inhibited by RNAi of mig-1 in F1-G. In addition, after PS-NP exposure, germline RNAi of lin-44 at P0-G could increase the mig-1 expression in F1-G. Exposure to PS-NP (1-100 μg/L) further decreased expressions of Dishevelled proteins of DSH-1/2, increased APC complex component APR-1, and decreased expression of BAR-1/β-catenin. Meanwhile, transgenerational PS-NP toxicity was enhanced by RNAi of dsh-1, dsh-2, or bar-1 and inhibited by RNAi of apr-1, suggesting that the DSH-1/2-APR-1-BAR-1 signaling cascade acted downstream of Wnt receptor MIG-1 to control transgenerational PS-NP toxicity. Moreover, BAR-1 acted upstream of DVE-1 to activate mitochondrial unfolded protein response (mt UPR) against the transgenerational PS-NP toxicity. Our data highlights the potential link between alteration in germline Wnt signaling and induction of transgenerational nanoplastic toxicity in organisms.

Nanoplastics cause transgenerational toxicity through inhibiting germline microRNA mir-38 in C. elegans

Nanoplastic exposure potentially caused the induction of transgenerational toxicity. Nevertheless, the molecular basis for nanoplastic exposure-induced transgenerational toxicity remains largely unclear. Using Caenorhabditis elegans as an animal model, we examined the role of germline microRNA (miRNA) mir-38 in regulating the transgenerational toxicity of polystyrene nanoparticles (PS-NPs). After the exposure, 1-100 μg/L PS-NP decreased expression of germline mir-38. Meanwhile, germline mir-38 overexpression conferred a resistance to transgenerational PS-NP toxicity, which suggested that the decrease in germline mir-38 mediated the induction of transgenerational PS-NP toxicity. In the germline, mir-38 regulated transgenerational PS-NP toxicity by inhibiting activity of downstream targets (NDK-1, NHL-2, and WRT-3). Among these three downstream targets, germline NDK-1 further controlled transgenerational PS-NP toxicity by suppressing the function of KSR-1/2, two kinase suppressors of Ras. Therefore, in the germline, the decrease in mir-38 mediated induction of transgenerational PS-NP toxicity by at least inhibiting signaling cascade of NDK-1-KSR-1/2 in nematodes. The findings in this study are helpful for providing relevantly molecular endpoints to assess potential transgenerational toxicity of nanoplastics.

A critical review of advances in reproductive toxicity of common nanomaterials to Caenorhabditis elegans and influencing factors

In recent decades, nanotechnology has rapidly developed. Therefore, there is growing concern about the potential environmental risks of nanoparticles (NPs). Caenorhabditis elegans (C. elegans) has been used as a powerful tool for studying the potential ecotoxicological impacts of nanomaterials from the whole animal level to single cell level, especially in the area of reproduction. In this review, we discuss the reproductive toxicity of common nanomaterials in C. elegans, such as metal-based nanomaterial (silver nanoparticles (NPs), gold NPs, zinc oxide NPs, copper oxide NPs), carbon-based nanomaterial (graphene oxide, multi-walled carbon nanotubes, fullerene nanoparticles), polymeric NPs, silica NPs, quantum dots, and the potential mechanisms involved. This insights into the toxic effects of existing nanomaterials on the human reproductive system. In addition, we summarize how the physicochemical properties (e.g., size, charge, surface modification, shape) of nanomaterials influence their reproductive toxicity. Overall, using C. elegans as a platform to develop rapid detection techniques and prediction methods for nanomaterial reproductive toxicity is expected to reduce the gap between biosafety evaluation of nanomaterials and their application.

Parental exposures increase the vulnerability of copepod offspring to copper and a simulated marine heatwave

Extreme temperatures from marine heatwaves (MHWs) and pollution are dominant stressors in tropical marine ecosystems. However, we know little about the role of transgenerational effects of metals and MHWs in shaping the offspring's vulnerability to these stressors. We addressed this fundamental knowledge gap by exposing the planktonic copepod Pseudodiaptomus incisus to copper (Cu: control, 15 and 60 μg L^-1) under 2 temperatures (30 and a simulated marine heatwave at 34 °C) in the first generation (F1) and 16 treatments in F2: offspring from each of 4 F1 conditions (control or 15 μg Cu L^-1 × 30 or 34 °C) was reared in 4 F2 conditions (control or 15 μg Cu L^-1 × 30 or 34 °C). We assessed changes in copepod performance, particularly survival, adult size, grazing, and reproduction. In F1, Cu or marine heatwave (MHW) exposures reduced all fitness traits of F1; the effects were particularly strong when both stressors were present. Transgenerational effects of Cu or MHW also strongly reduced F2 performance. Direct Cu and MHW effects on the offspring were further strengthened by transgenerational effects, resulting in more substantial reductions in F2 performance when both generations were exposed to these stressors. As copepods are major food resources for corals, shrimps, or fish larvae and juveniles, strong transgenerational and direct effects of Cu and MHW can have a cascading effect on entire coastal food webs. These results highlight the importance of considering the interaction of transgenerational and direct effects of multiple stressors, particularly relevant for short-lived organisms in tropical marine ecosystems.

Damages to biological macromolecules in gonadal subcellular fractions of scallop Chlamys farreri following benzo[a]pyrene exposure: Contribution to inhibiting gonadal development and reducing fertility

Benzo[a]pyrene (B[a]P), a representative polycyclic aromatic hydrocarbon (PAH) compound in marine ecosystem, has great potential for chronic toxicity to marine animals. It is becoming increasingly apparent that reproductive system is the major target of B[a]P, but the adverse effects of B[a]P on subcellular fractions in bivalve gonads have not been elucidated. Scallops Chlamys farreri are used as the experimental species since they are sensitive to environmental pollutants. This study was conducted to investigate how B[a]P affected the gonadal subcellular fractions, including plasma membrane, nucleus, mitochondria and microsome in scallops, and whether subcellular damages were related to reproductive toxicity. The results showed that mature gametes' counts were significantly decreased in B[a]P-treated scallops. Three biological macromolecules (viz., DNA, lipids and proteins) in gonadal subcellular fractions obtained by differential centrifugation suffered damages, including DNA damage, lipid peroxidation and protein carbonylation in B[a]P treatment groups. Interestingly, mitochondria and microsome were more vulnerable to lipid peroxidation and protein carbonylation than plasma membrane and nucleus, meanwhile males were more susceptible to DNA damage than females under B[a]P exposure. In addition, histological analysis showed that B[a]P delayed gonadal development in C. farreri. To summarize, our results indicated that B[a]P caused damages to biological macromolecules in gonadal subcellular fractions and then induced damages to gonadal tissues of C. farreri, which further inhibited gonadal development and ultimately leaded to reduction in fertility. This study firstly reports the impacts of PAHs on subcellular fractions in bivalves and their relationship with reproductive toxicity. Moreover, exposure of reproductive scallops to B[a]P leads to defects in reproduction, raising concerns on the possible long-term consequences of PAHs for natural populations of bivalves.

Long-term nanoplastics exposure results in multi and trans-generational reproduction decline associated with germline toxicity and epigenetic regulation in Caenorhabditis elegans

The environmental risk from long-term plastic pollution is growing. We investigated the multi and trans-generational reproductive toxicity of nanoplastics (NPs) in Caenorhabditis elegans and the underlying mechanisms over five generations. Following a single maternal exposure (F0) to NPs (100 nm; 1, 10, 50, or 100 mg/L) for 72 h, the subsequent generations (F1-F4) were cultured under NPs-free conditions. We showed that the total brood size was significantly reduced across all offspring generations (F1-F4). NPs accumulated in the intestine of C. elegans in the F0 generation, but not in the germline system, and not observed in subsequent generations. Chromosomal aberrations in oocytes and germline cell apoptosis were significantly elevated in the NPs-exposed F0 generation and in subsequent unexposed generations. Likewise, the expression of ced-3 was increased across generations, regulated by hypomethylation in the promoter region of ced-3 after maternal NPs exposure. Finally, NPs exposure reduced the expression of epigenesis-related genes met-2, set-2, and spr-5 and the trans-generational effects of maternal NPs exposure were not observed in met-2, set-2, and spr-5 RNAi worms. We demonstrate that a single long-term maternal NPs exposure can cause multi and trans-generational reproduction decline in C. elegans, which may be associated with germline toxicity and epigenetic regulation.

Metal- and metal/oxide-based engineered nanoparticles and nanostructures: a review on the applications, nanotoxicological effects, and risk control strategies

The production and demand of nanoparticles in the manufacturing sector and personal care products, release a large number of engineered nanoparticles (ENPs) into the atmosphere, aquatic ecosystems, and terrestrial environments. The intentional or involuntary incorporation of ENPs into the environment is carried out through different processes. The ENPs are combined with other compounds and release into the atmosphere, settling on the ground due to the water cycle or other atmospheric phenomena. In the case of aquatic ecosystems, the ENPs undergo hetero-aggregation and sedimentation, reaching different living organisms and flora, as well as groundwater. Accordingly, the high mobility of ENPs in diverse ecosystems is strongly related to physical, chemical, and biological processes. Recent studies have been focused on the toxicological effects of a wide variety of ENPs using different validated biological models. This literature review emphasizes the study of toxicological effects related to using the most common ENPs, specifically metal and metal/oxides-based nanoparticles, addressing different synthesis methodologies, applications, and toxicological evaluations. The results suggest negative impacts on biological models, such as oxidative stress, metabolic and locomotive toxicity, DNA replication dysfunction, and bioaccumulation. Finally, it was consulted the protocols for the control of risks, following the assessment and management process, as well as the classification system for technological alternatives and risk management measures of ENPs, which are useful for the transfer of technology and nanoparticles commercialization.