Fullerene C60 nanomaterial induced oxidative imbalance in gonads of the freshwater fish, Anabas testudineus (Bloch, 1792)

Potential toxicity of carbonaceous nanomaterials on aquatic organisms and their alleviation strategies: A review

Carbonaceous nanomaterials (CNMs) are widely used in electronics, biomedicine, agriculture, environmental remediation, and catalysis due to their excellent biocompatibility, high reactivity, and high specific surface area. However, the extensive applications of CNMs cause their inevitable release into water, which may result in toxic effects on the aquatic ecological environment and organisms. CNMs can cause lipid peroxidation damage and neurotoxicity in aquatic organisms, affecting embryo hatching and larval morphology. The effects of CNMs on aquatic organisms vary depending on their structures and physicochemical properties, as well as the species, age, and tolerance of the tested organisms. The above uncertainties have increased the difficulty of exploring the impact of carbonaceous nanomaterials on the toxicity of aquatic organisms to a certain extent. Solving these issues is of great significance and reference value for promoting the research and safe utilization of carbon nanomaterials. Therefore, a systematic review of the effects of potential toxicity of carbonaceous nanomaterials on aquatic organisms and their alleviation strategies is needed. This paper firstly summarizes the toxic effects of commonly used CNMs (i.e., carbon nanotubes, graphene, and fullerene) on different aquatic organisms, which include developmental toxicity, behavioral and metabolic toxicity, reproductive toxicity, and organ toxicity. Then the main mechanisms of CNMs to aquatic organisms are further explored, and the methods to reduce the toxicity of CNMs are also summarized. Finally, the current challenges and future perspectives for studying CNM toxicity to aquatic organisms are proposed.

Chronic toxicity and liver histopathology of mosquito fish (Gambusia holbrooki) exposed to natural and modified nanoclays

Nanoclays are found in the air, water, and soil, and modified nanoclays are being developed and used in several consumer products. For example, modified nanoclays are used to remove pollutants from wastewater. Ironically, however, nanoclays are now considered emerging contaminants. Indeed, release of modified nanoclays in aquatic systems, even as remediating agents, could adversely affect associated wildlife. However, aquatic organisms have interacted with natural nanoclays for millennia, and it is unclear if modified nanoclays induce stronger effects than the nanoclays that occur naturally. The concentrations over which nanoclays occur and illicit negative effects are not well studied. This study investigated the dose response of a natural nanoclay (Na+montmorillonite) relative to two modified nanoclays (Cloisite®30B and Novaclay™) on survival, body condition, and liver pathomorphology of Gambusia holbrooki after 14 days of exposure. Although none of the nanoclays affected survival and body condition of G. holbrooki over 14 days, each nanoclay induced histopathological changes in liver tissues at very low concentrations (LOAEL: 0.01 mgL-1). The effects of nanoclays on hepatic cell circulatory (blood cell aggregation with increased number of Kupffer cells and hemosiderin deposits), regressive (hepatocyte vacuolization), and degenerative (cell death) changes of mosquito fish varied among nanoclay types. Novaclay™ at low concentrations caused circulatory changes on hepatic tissues of G. holbrooki, whereas both natural nanoclays and Cloisite®30B showed little effect on circulatory endpoints. In contrast, all of the nanoclays induced regressive and degenerative changes on liver tissues of mosquito fish across all concentrations tested. This study clearly reveals that natural and modified nanoclays have important health implications for fish and other aquatic organisms. Consequently, the widespread use of modified nanoclays in several applications and increased release of natural nanoclays through erosion or other processes needs to be evaluated in more detail especially in the context of their safety for aquatic systems.

Reduction of cryopreservation-induced structural, functional and molecular damages in ram sperm by hydrated C60 fullerene

This study aimed to investigate the morphological, functional and molecular changes in frozen-thawed ram sperm using an extender containing different concentrations of hydrated carbon 60 fullerene (C60 HyFn), a nanotechnological product. Semen taken from each of the seven Akkaraman rams were pooled. Semen collection was done twice a week and it continued for 3 weeks. Each pooled semen sample was divided into six equal groups and diluted with tris + egg yolk extender including 0 (control), 200, 400, 800 nM, 1 and 5 μM concentrations of C60 HyFn at 37°C. They were then frozen in liquid nitrogen vapour at -140°C, stored in liquid nitrogen container (-196°C) and thawed at 37°C for 25 s before analysis. In comparison with control, C60 HyFn addition prior to freezing procedure provided significant increases in total and progressive motility rates, glutathione peroxidase, catalase activities and percentage of highly active mitochondria, and significant decreases in dead and abnormal sperm rates, lipid peroxidation, caspase-3 and DNA fragmentation levels in frozen-thawed ram semen. When compared to control, C60 HyFn supplementation significantly down-regulated the expression levels of miR-200a and KCNJ11, and significantly up-regulated the expression levels of miR-3958-3p (at the concentrations of 200, 400, 800 nM and 1 μM), CatSper1 (at the concentrations of 200, 400 nM and 5 μM), CatSper2 (at the concentrations of 1 and 5 μM), CatSper3 (at the concentrations of 200, 400 nM, 1 and 5 μM), CatSper4 (at all concentrations), ANO1 (at the concentrations of 800 nM, 1 and 5 μM) and TRPV5 (at the concentrations of 200, 400 and 800 nM). The addition of C60 HyFn had no effect on global DNA methylation rates. As a result, C60 HyFn supplementation to ram semen extenders may be beneficial in reducing some of the functional, structural and molecular damages in sperm induced by the freeze-thawing procedure.

Cheminformatics and Machine Learning Approaches to Assess Aquatic Toxicity Profiles of Fullerene Derivatives

Fullerene derivatives (FDs) are widely used in nanomaterials production, the pharmaceutical industry and biomedicine. In the present study, we focused on the potential toxic effects of FDs on the aquatic environment. First, we analyzed the binding affinity of 169 FDs to 10 human proteins (1D6U, 1E3K, 1GOS, 1GS4, 1H82, 1OG5, 1UOM, 2F9Q, 2J0D, 3ERT) obtained from the Protein Data Bank (PDB) and showing high similarity to proteins from aquatic species. Then, the binding activity of 169 FDs to the enzyme acetylcholinesterase (AChE)-as a known target of toxins in fathead minnows and Daphnia magna, causing the inhibition of AChE-was analyzed. Finally, the structural aquatic toxicity alerts obtained from ToxAlert were used to confirm the possible mechanism of action. Machine learning and cheminformatics tools were used to analyze the data. Counter-propagation artificial neural network (CPANN) models were used to determine key binding properties of FDs to proteins associated with aquatic toxicity. Predicting the binding affinity of unknown FDs using quantitative structure-activity relationship (QSAR) models eliminates the need for complex and time-consuming calculations. The results of the study show which structural features of FDs have the greatest impact on aquatic organisms and help prioritize FDs and make manufacturing decisions.

Polyvinyl chloride microplastics induce changes in gene expression and organ histology along the HPG axis in Cyprinus carpio var. larvae

The negative consequences of microplastics pollution on the health of aquatic species have garnered extensive attention. However, the mechanisms through which microplastics may cause harm in the reproductive processes of fish remain unknown. For this study, Cyprinus carpio var. was subjected to four treatments with various concentrations of PVC microplastics for 60 days, through food rationed diets (no plastic control, 10%, 20% and 30%). The gonadosomatic indices, gonad and brain histologies, sex hormone levels, and transcriptional and translational genes in the hypothalamic-pituitary-gonadal (HPG) axes of both sexes were observed. According to the results, the gonadosomatic indices were significantly decreased, gonadal development was delayed, and the level of estradiol (E2) in the females was significantly elevated. In addition, the expression levels of genes associated with the HPG axis in the brains and gonads (gnrh, gtha1, fshβ, cyp19b, erα, vtg1, dmrt1, sox9b, and cyp19a) and the transcription levels of apoptosis-related genes in the brains and gonads (caspase3, bax, and bcl-2) exhibited significant changes. Further investigation revealed that the translation levels of genes linked to sex differentiation and sex steroid hormone (cyp19b and dmrt1) were significantly altered. These findings indicated that PVC likely microplastics may have a negative impact on the reproductive system of Cyprinus carpio var. by inhibiting gonadal development, affecting the gonad and brain structures, and altering the levels of steroid hormones and the expression of HPG axis-related genes. This work provides new insights into the toxicity of microplastics in aquatic organisms by revealing that PVC microplastics are a potential threat against the reproduction of fish populations.

Carbon nanostructures: a comprehensive review of potential applications and toxic effects

There is no doubt that nanotechnology has revolutionized our life since the 1970s when it was first introduced. Nanomaterials have helped us to improve the current products and services we use. Among the different types of nanomaterials, the application of carbon-based nanomaterials in every aspect of our lives has rapidly grown over recent decades. This review discusses recent advances of those applications in distinct categories, including medical, industrial, and environmental applications. The first main section introduces nanomaterials, especially carbon-based nanomaterials. In the first section, we discussed medical applications, including medical biosensors, drug and gene delivery, cell and tissue labeling and imaging, tissue engineering, and the fight against bacterial and fungal infections. The next section discusses industrial applications, including agriculture, plastic, electronic, energy, and food industries. In addition, the environmental applications, including detection of air and water pollutions and removal of environmental pollutants, were vastly reviewed in the last section. In the conclusion section, we discussed challenges and future perspectives.

Gut microbiota of Anabas testudineus (Bloch, 1792) in the e-waste dismantling region: In situ status and relationship with internal metal burden

Due to the production of large quantities of electronic waste (e-waste), unsafe dismantling has caused serious pollution as well as toxicological impacts on both wildlife and humans. As an important aspect of physiology and health, the wildlife's gut microbiota and its changes induced by pollution have been recruiting increasing concerns. To reveal the gut microbiota-related ecotoxicology induced by e-waste dismantling, this study resolves the gut microbiota profile of Anabas testudineus, a native highly adapted nonmodel fish under the in situ exposure, and reveals whether and how the microbiota was altered. The comparisons are made by collecting samples from different e-waste polluted sites in Guiyu (a town in South China) and a nearby reference (nonpolluted) site. The overall gut microbiota landscape of A. testudineus is similar to that of other reported fishes, with an average of ∼300 OTUs, and constituted by Firmicutes (34.51%), Fusobacteria (29.16%) as the major phyla. Obviously different liver metal burdens/fingerprints were observed between the e-waste and reference sites. Accordingly, although the alpha-diversity (ACE, Simpson, and Shannon) of the gut microbiota did not significantly vary, a detailed exploration of the microbiota constitution indicated significant differences at various taxonomic levels, including a series of significantly different species and biomarkers, and showing site-specific beta-diversity clustering patterns. Interestingly, a few bacteria with greater abundance in the fish gut of e-waste polluted sites were also reported to present in other contaminated environments, have a role in wastewater treatment, be capable to transform metal, etc. Redundancy analysis (RDA) and Pearson association analyses indicated significant associations between Mn and Cetobacterium somerae (Pearson r = 0.3612, p = 0.0008) and between Pb and Clostridium colicanis (Pearson r = 0.5151, p < 0.0001). In summary, pollution from e-waste dismantling may have a role in altering the fish gut microbiota, and this research provides insights for better understanding e-waste ecotoxicology and improving future conservation.

Reproductive and Developmental Nanotoxicity of Carbon Nanoparticles

The presented review aims to summarize the knowledge regarding the reproductive and developmental toxicity of different types of carbon nanoparticles, such as graphene, graphene oxide, multi- and single-walled nanotubes, fullerenes, and nanodiamonds. Carbon nanoparticles have unique chemical and physical properties that make them an excellent material that can be applied in many fields of human activity, including industry, food processing, the pharmaceutical industry, or medicine. Although it has a high degree of biocompatibility, possible toxic effects on different tissue types must also be taken into account. Carbon nanoparticles are known to be toxic to the respiratory, cardiovascular, nervous, digestive system, etc., and, according to current studies, they also have a negative effect on reproduction and offspring development.

Long term exposure to tris (2-chloroethyl) phosphate (TCEP) causes alterations in reproductive hormones, vitellogenin, antioxidant enzymes, and histology of gonads in zebrafish (Danio rerio): In vivo and computational analysis

In aquatic milieus, tris (2-chloroethyl) phosphate (TCEP) was detected as an emerging environmental contaminant. In this study, in vivo experiment and in-silico docking was integrated systematically to explore the toxic mechanisms of TCEP using zebrafish (Danio rerio). Fish (mean weight of 0.24 ± 0.02 g) were exposed to 100 and 1500 μg L^-1 concentrations of TCEP for 28 days under the static renewal method. During chronic exposure, plasma steroid hormones such as testosterone (T) and 17β estradiol (E2), plasma vitellogenin (Vtg) and antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), and lipid peroxidation (LPO) in gonads were significantly (P < 0.05) altered in TCEP exposed group (1500 μg L^-1) compared to the control group. However, the alterations of these parameters were not significant on the 14th day (except Vtg and GR in testis) in 100 μg L^-1 of TCEP exposed groups. There were no significant differences (p > 0.05) in the growth parameters comparing TCEP exposed groups with the control group. The gonads of fish exposed to TCEP showed significant histopathological changes when compared to the control groups. A docking study observed that TCEP possessed binding affinity with the estrogen receptor (ERβ) and androgen receptor (AR). These data indicate that TCEP at tested concentrations adversely affects the aquatic organisms.

Advantages and prospective challenges of nanotechnology applications in fish cultures: a comparative review

Applications of nanotechnology in fish cultures have participated in getting over various difficulties that hinder fish productivity. They can achieve growth performance after adding some important minerals and vitamins in the form of nano-feed supplements like selenium, zinc, iron, and vitamin C. Also, they have an important role in reproduction, and fish medicine as antimicrobial, drug delivery, nano-vaccination, and rapid disease diagnosis. Moreover, their roles in water remediation and purification, and fish packaging are documented. On the other hand, some nanoparticles exhibit toxic effects on living organisms, which return to their tiny size, high reactivity, and permeability. They can alter many physiological functions and cause cytotoxicity, DNA damage, and histopathological changes. Also, nanotechnology applications cause new secondary pollutants to be introduced into the environment that can negatively affect fish health and the surrounding living organisms. So, in spite of the promising applications of nanotechnology to fulfill high growth performance and pathogen-free fish, there are a lot of debates about the potential toxicity of nanomaterials, their reactivity with the surrounding environment, and bioaccumulation. The present review aims to elucidate and discuss various advantages and challenges of nanotechnology applications in fish cultures. Also, it points to green nanotechnology as a promising alternative to chemical ones.

Intra and extracellular effects of benzo [α] pyrene on liver, gill and blood of Caspian White fish (Rutilus frissi kutum): Cyto-genotoxicity and histopathology approach

Southern parts of the Caspian Sea have been faced with a diverse range of oil pollutants. Therefore, this study was designed to evaluate the effects of relevant environmental concentrations of benzo[α]pyrene (BαP) on liver, gill, and blood of Caspian White fish. To this end, 150 fingerling fish (6.5 ± 0.8 g) were exposed to under, near and over environmental concentrations of BαP (i.e. 50, 100, and 200 ppb, respectively) and two control groups for 21 days. Following exposure to BαP, generally, DNA damage increased in the liver and gill cells as well as the frequency of micro- and bi-nucleated erythrocytes in a time and concentration-dependent pattern. In addition, the liver and gill tissues displayed several histopathological lesions. Together, the findings are warning the health status of the Caspian Sea due to an ever-increasing concentration of BαP through using Caspian White fish as an ecological model.

Possible role of C60 fullerene in the induction of reproductive toxicity in the freshwater fish, Anabas testudineus (Bloch, 1792)

In recent years, the impact of ultrafine nanomaterials on the aquatic organisms and their ecosystems contributed much concern due to their abundance in environment. Several toxicity studies have reported that nanoparticles induced reproductive stress and resulted in reproductive impairment of fishes. The present study was aimed to investigate the stress-induced toxicity of C₆₀ fullerene nanomaterial on various reproductive parameters of the freshwater fish, Anabas testudineus. Fish were exposed to two sublethal concentrations of fullerene C₆₀, one-tenth (5 mg/L) and one-fifth (10 mg/L) of LC₅₀-96 h, for 4, 7, 15, 30, and 60-day durations. At the end of exposure period, the activities of steroidogenic enzymes, 3β-, and 17β-hydroxysteroid dehydrogenase decreased in the testis and ovary thereby indicated that the nanomaterial affected gonadal steroidogenesis. The level of serum testosterone decreased significantly (p < 0.05) in male whereas the level of estradiol showed significant (p < 0.05) reduction in female fish with significant (p < 0.05) increase in the level of serum cortisol in both sexes in concentration- and time-dependent manner. The analysis of the levels of alkali-labile phosphates, plasma calcium, and total protein showed significant (p < 0.05) reduction in female fish without significant changes in male fish, and this could be due to the antiestrogenic action of fullerene C₆₀ nanomaterial. The activity of aromatase enzyme decreased significantly (p < 0.05) in the ovary and brain of female fish, and the decline in the enzyme activity was prominent only in the brain tissue of male fish. The present results suggested that the stress-induced by fullerene C₆₀ exposure provoked reproductive toxicity in the fish, Anabas testudineus.

Fullerene Derivatives as Lung Cancer Cell Inhibitors: Investigation of Potential Descriptors Using QSAR Approaches

Background

Nanotechnology-based strategies in the treatment of cancer have potential advantages because of the favorable delivery of nanoparticles into tumors through porous vasculature.

Materials and Methods

In the current study, we synthesized a series of water-soluble fullerene derivatives and observed their anti-tumor effects on human lung carcinoma A549 cell lines. The quantitative structure–activity relationship (QSAR) modeling was employed to investigate the relationship between anticancer effects and descriptors relevant to peculiarities of molecular structures of fullerene derivatives.

Results

In the QSAR regression model, the evaluation results revealed that the determination coefficient r² and leave-one-out cross-validation q² for the recommended QSAR model were 0.9966 and 0.9246, respectively, indicating the reliability of the results. The molecular modeling showed that the lack of chlorine atom and a lower number of aliphatic single bonds in saturated hydrocarbon chains may be positively correlated with the lung cancer cytotoxicity of fullerene derivatives. Synthesized water-soluble fullerene derivatives have potential functional groups to inhibit the proliferation of lung cancer cells.

Conclusion

The guidelines obtained from the QSAR model might strongly facilitate the rational design of potential fullerene-based drug candidates for lung cancer therapy in the future.

Decreased malondialdehyde levels in fish (Astyanax altiparanae) exposed to diesel: Evidence of metabolism by aldehyde dehydrogenase in the liver and excretion in water

Increased malondialdehyde (MDA) levels are commonly considered an indicator of lipid peroxidation derived from oxidative stress insults promoted by exposure of fish to pollutants. However, a decrease in MDA levels after xenobiotic exposure has been also reported, an effect that is mostly attributed to enhanced antioxidant defenses. In this study, we assessed whether pollutant-mediated MDA decrease would be associated with antioxidant enhancement or with its metabolism by aldehyde dehydrogenase (ALDH) in the liver and gills of lambari (Astyanax altiparanae) exposed to diesel oil (0.001, 0.01, and 0.1 mL/L). MDA levels were decreased in the liver of lambari exposed to diesel. The activities of the antioxidant enzymes, catalase (CAT) and glutathione peroxidase (GPx), were unchanged in the liver, while that of glucose-6-phosphate dehydrogenase (G6PDH) was decreased. In contrast, levels of total glutathione (tGSH) and the activity of glutathione S-transferase (GST) were increased in the liver, which partly support antioxidant protection against lipid peroxidation. More importantly, ALDH activity increased in a concentration-dependent manner, being negatively correlated with MDA levels, indicating MDA metabolism by ALDH. In the gills, diesel exposure increased MDA and lipid hydroperoxide levels, and promoted increases in antioxidant defenses, indicating oxidative stress. Curiously, ALDH activity was undetectable in the gills, supporting the possibility of direct MDA excretion in the water by the gills. Analyses of MDA in the water revealed increased levels of MDA in the aquaria in which the fish were exposed to diesel, compared to control aquaria. A second experiment was carried out in which the fish were intraperitoneally injected with MDA (10 mg/kg) and analyzed after 1, 6, and 12 h. MDA injection caused a time-dependent decrease in hepatic MDA levels, did not alter ALDH, CAT, GPx, and GST activities, and decreased G6PDH activity and tGSH levels. In the gills, MDA injection caused a slight increase in MDA levels after 1 h, but did not alter GPx, G6PDH, and GST activities. MDA injection also enhanced CAT activity and tGSH levels in the gills. MDA concentration in water increased progressively after 1, 6, and 12 h, supporting the hypothesis of direct MDA excretion as an alternative route for MDA elimination in fish. Our results suggest that the decreased MDA levels after exposure of lambari to diesel oil pollutant probably reflects an association between enhanced antioxidant protection, MDA metabolism, and MDA excretion in water.

Cytogenotoxic effects of fullerene C60 in the freshwater teleostean fish, Anabas testudineus (Bloch, 1792)

In recent years, carbon nanomaterials, including fullerene C₆₀ is regarded as the building block in nanotechnology because of its widespread use in medicine, industry, cosmetics and commercial products. Despite the special properties, several reports have raised public health concerns due to the unknown and practically unexplored toxic effects of nanomaterials. However, there have been relatively few studies regarding the genotoxic responses of fullerene C₆₀in vivo. Genotoxic effects of DMSO-solublized C₆₀ nanomaterial suspension at sublethal concentrations (5 and 10 mg/L) were investigated on adult freshwater fish, Anabas testudineus using micronucleus and comet assays. An assessment of micronucleus induction showed severe cytoplasmic and nuclear abnormalities in erythrocytes, gill and liver cells. Abnormalities in cytoplasm were identified as formation of sticky cells, vacuolated cytoplasm, cytoplasmic degeneration, echinocyte, acanthocyte, anisochromatic cells and abnormal erythrocyte membrane. The nuclear abnormalities included micronucleus, binucleated cells, nuclear buds, irregular nucleus, vacuolated, notched and serrated nucleus in the erythrocytes compared to the control groups. Similarly, significant increase (P < 0.05) in micronucleus frequencies were observed in gill and liver cells. The high frequency of micronucleus was observed in the gill cells followed by liver and erythrocytes, respectively, at both sublethal concentrations, and the severity was duration and concentration-dependent. In comet assay, significant increase (P < 0.05) in DNA damage was observed using the comet parameter, percent tail DNA. The highest level of comet damage with grade 3 was observed in blood, gill and liver cells on increase in duration and concentration when compared to the respective control groups. Thus the results revealed that fullerene C₆₀ nanomaterials may pose risk to aquatic organisms, especially fish, by the induction of genotoxicity. Further studies are warranted to provide new insights on the mechanisms and consequences of C₆₀ nanomaterials interactions with biological membranes.