Dietary exposure to titanium dioxide nanoparticles in rainbow trout, (Oncorhynchus mykiss): no effect on growth, but subtle biochemical disturbances in the brain

Dietary nano-Selenium supplementation improves growth performance, nutrient digestibility and hematology in Cirrhinus mrigala fingerlings

The following investigation was carried out to determine the effects of Selenium nanoparticles (Se NPs) on the growth rates, nutrient digestibility, and hematology of Cirrhinus mrigala fingerlings fed sunflower meal as basal diet. The experiment included seven test diets with varying Se levels (0, 0.5, 1, 1.5, 2, 2.5, and 3 mg/kg) based on Se NPs supplementation. Chromic oxide, an inert maker, was also added. Fingerlings were fed at a rate of 5% of their body weight. The test meal of 1 mg/kg Se NPs resulted in the highest weight gain (12.31 g) and the lowest feed conversion ratio (1.58). Best hematological indices (RBCs 2.84 106 mm-3, WBCs 7.79 103 mm-3, PLT 66, Hb 8.5 g/100 ml, PCV 25% and MCV 190 fl) and maximum nutrient absorption (crude protein 72%, ether extract 73% and gross energy 67%) were also observed in the case of 1 mg/kg supplementation of Se NPs. Hematology studies indicated that when fish were fed 0.5 mg/kg Se NPs, their levels began to rise. Maximum results were achieved with feed containing 1 mg/kg of Se NPs, but when the concentration increased above 1 mg/kg, the values began to decline. Instead, nutrient digestibility began to increase when the concentration of Se NPs increased to 1 mg/kg and abruptly started to decline with a further increase in Se NPs. The results demonstrated that a sunflower meal-based diet supplemented with Se NPs (1 mg/kg) increased the growth performance, nutritional digestibility, and hematology of C. mrigala fingerlings.

Assessing the in vivo toxicity of titanium dioxide nanoparticles in Schmidtea mediterranea: uptake pathways and (neuro)developmental outcomes

Titanium dioxide nanoparticles (TiO2-NPs) in aquatic environments, originating from urban run-off, product use and post-consumer degradation, interact with aquatic organisms through water and sediments. Thorough toxicity assessment requires comprehensive data across all ecosystem compartments especially the benthic zone, which is currently lacking. Moreover, a proper physicochemical characterization of the particles is needed before and during toxicity assessment. In the present work, we used the planarian Schmidtea mediterranea to investigate the effects of TiO2-NPs (5 mg/L and 50 mg/L). Planarians are benthic organisms that play an important role in the food chain as predators. Our study integrated particle characterization with toxicokinetic and toxicodynamic parameters and showed that the uptake of TiO2-NPs of 21 nm occurred through the epidermis and intestine. Epidermal irritation and mucus production occurred immediately after exposure, and TiO2-NPs induced stronger effects in regenerating organisms. More specifically, TiO2-NPs interfered with neuroregeneration, inducing behavioral effects. A delay in the formation of the anterior commissure between the two brain lobes after seven and nine days of exposure to 50 mg/L was observed, probably as a result of a decrease in stem cell proliferation. Our findings underscore the need to incorporate multiple exposure routes in toxicity screenings. Additionally, we highlight the vulnerability of developing organisms and recommend their inclusion in future risk assessment strategies.

The toxicological effects of nano titanium dioxide on target organs and mechanisms of toxicity

Nano-titanium dioxide (TiO2 NPs) is widely used for its extremely high stability, corrosion resistance, and photocatalytic properties and has penetrated into various fields of production and life. Assessing its toxicity to different organs should be a key part of preclinical toxicity assessment of TiO2 NPs, which is relatively incomprehensive yet. Therefore, this review focuses on the toxic effects of TiO2 NPs on various organs in mammals and biological mechanisms from different organs. The commonality of toxic effects on various target organs reflected in tissue structure damage and dysfunction, such as liver damage and dysfunction; pulmonary fibrosis; and renal impairment (including hematuria and nephritis); damage of brain tissue and neurons; alteration of intestinal villi; and weight loss. And effects on the reproductive system are affected by different sexes, including ovarian dysfunction, testicular development damage, and sperm viability reduction. We believe that the toxic mechanisms of TiO2 NPs in target organs have commonalities, such as oxidative stress, inflammatory responses, and organelle damage. However, different target organ toxicities also have their specificities. TiO2 NPs disturb the intestinal flora and cause undesirable changes in feces products. And in spleen are infiltration of neutrophils and lymphadenopathy and eventually immune deficiency. Although the toxic pathways are different, but there may be a close link between the different toxic pathways. In this article, the main manifestations of the toxic effects of titanium dioxide nanoparticles on major mammalian organs are reviewed, in order to provide basic data for their better application from a medical perspective.

Subchronic toxicity of iron-selenium nanoparticles on oxidative stress response, histopathological, and nuclear damage in amphibian larvae Rana saharica

In this work, we evaluated the subchronic toxicity of FeSe nanoparticles (NPs) in tadpoles of Rana saharica. Tadpoles were exposed for 1-3 weeks to FeSe NPs at 5 mg/L and 100 mg/L rates. Parameters of oxidative stress were measured in whole larvae, and the micronucleus test was performed on circulating blood erythrocytes. We noted a disturbance of the detoxification systems. Enzymatic and non-enzymatic data showed that exposure to FeSe NPs involved a highly significant depletion of GSH, a significant increase in GST activity, and a lipid peroxidation associated with a highly significant increase in MDA. We also noted a neurotoxic effect characterized by a significant inhibition of AChE activity. A micronucleus test showed concentration-dependent DNA damage. This research reveals that these trace elements, in their nanoform, can cause significant neurotoxicity, histopathologic degeneration, cellular and metabolic activity, and genotoxic consequences in Rana larvae.

The Effect of Silver Nanoparticles on the Digestive System, Gonad Morphology, and Physiology of Butterfly Splitfin (Ameca splendens)

The aim of this study was to determine the effects of silver nanoparticles (AgNPs) on the morphology and enzymatic activity of butterfly splitfin (Ameca splendens). Individuals of both sexes, aged about five months, were exposed to AgNPs at concentrations of 0 (control group), 0.01, 0.1, and 1.0 mg/dm3 for 42 days. On the last day of the experiment, the fish were euthanized, subjected to standard histological processing (anterior intestine, liver, and gonads), and analysed for digestive enzyme activity in the anterior intestine and oxidative stress markers in the liver. Fish in the AgNP 0.01 and 0.1 groups had the lowest anterior intestinal fold and enterocyte height. However, there were no statistically significant changes in the digestive enzyme activity in the anterior intestine. Analysis of enzymatic activity in the liver showed an increase in superoxide dismutase activity in fish in the AgNP 0.1 group. Histological analyses showed that AgNPs inhibited meiotic divisions at prophase I in a non-linear manner in ovaries and testes. In the AgNP 0.1 and 1.0 groups, the area occupied by spermatocytes was lower compared to the other groups. These results indicate that exposure to AgNPs may lead to disturbances in morphology and enzymatic activity in the liver and intestine and may lead to disruption of reproduction in populations.

Accumulation, Chronicity, and Induction of Oxidative Stress Regulating Genes Through Allium cepa L. Functionalized Silver Nanoparticles in Freshwater Common Carp (Cyprinus carpio)

Green evolutionary products such as biologically fabricated nanoparticles (NPs) pose a hazard to aquatic creatures. Herein, biogenic silver nanoparticles (AgNPs) were synthesized by the reaction between ionic silver (AgNO₃) and aqueous onion peel extract (Allium cepa L). The synthesized biogenic AgNPs were characterized with UV-Visible spectrophotometer, XRD, FT-IR, and TEM with EDS analysis; then, their toxicity was assessed on common carp fish (Cyprinus carpio) using biomarkers of haematological alterations, oxidative stress, histological changes, differential gene expression patterns, and bioaccumulation. The 96 h lethal toxicity was analysed with various concentrations (2, 4, 6, 8, and 10 mg/l) of biogenic AgNPs. Based on 96 h LC₅₀, sublethal concentrations (1/15^th, 1/10^th, and 1/5^th) were given to C. carpio for 28 days. At the end of experiment, the bioaccumulations of Ag content were accumulated mainly in the gills, followed by the liver and muscle. At an interval of 7 days, the haematological alterations showed significance (p < 0.05) and elevation of antioxidant defence mechanism reveals the toxicity of biogenic synthesized AgNPs. Adverse effects on oxidative stress were probably related to the histopathological damage of its vital organs like gill, liver, and muscle. Finally, the fish treated with biogenic synthesized AgNPs were significantly (p < 0.05) downregulates the oxidative stress genes such as Cu-Zn SOD, CAT, GPx1a, GST-α, CYP1A, and Nrf-2 expression patterns. The present study provides evidence of biogenic synthesized AgNPs influence on the aquatic life through induction of oxidative stress.

Considerations for bioaccumulation studies in fish with nanomaterials

Nanomaterials (NMs) pose challenges in performing bioaccumulation studies in fish and in regulatory interpretation of results. Therefore, a clear guidance is needed to obtain reliable, reproducible and comparable results. By analysing all the available literature, we aim in this manuscript to identify the critical aspects that should be addressed in these type of studies. Seventy-eight studies from a total of 67 published articles were identified in which a variety of approaches were used: aqueous exposure (49 studies), dietary exposure (19), and pre-exposed animals for trophic transfer studies (10). The NMs tested included TiO₂, Zn, ZnO, Cu, CuO, Ag, Au, CeO₂, Fe₂O₃, Fe₃O₄, Se, CdS, CdSe/ZnS-QDs, CdTe/ZnS-QDs, graphene, fullerenol and MWCNTs. In general, there is a scarcity of bioaccumulation studies for the different NMs. In particular, studies that use the dietary exposure route are lacking. TiO₂ NMs are the most studied for bioaccumulation potential in fish (20%), whereas very few data were available for CuO, FeO and carbon-based NMs. Different information gaps were identified in these studies that hamper overall conclusions to be made on the bioaccumulation potential of NMs. The main critical issues related to NM testing for bioaccumulation include: maintenance of stable exposure concentrations, the influence of feeding regimen on uptake and elimination, the use of appropriate feed spiking methodologies, the potential need for testing different concentrations, and the reporting of bioaccumulation endpoints (BCF/BMF). Each of these issues needs further guidance to allow proper use and reporting of NM bioaccumulation data for regulatory purposes.

Potential protective effects of Thyme (Thymus vulgaris) essential oil on growth, hematology, immune responses, and antioxidant status of Oncorhynchus mykiss exposed to Malathion

As an abundant source of antioxidants and diet flavor enhancers, the plant essential oils can have positive effects on fish growth, and resistance against environmental stressors. In this study, garden thyme (Thymus vulgaris) essential oil (TEO) was used in the diet of rainbow trout, Oncorhynchus mykiss, to evaluate its protective effect against Malathion pesticide exposure. Tested fish (19.99 ± 0.01 g) were divided into six groups (three replicates), namely: T1: control diet; T2: control diet + 0.025 mg L−1 malathion; T3: control diet + 0.075 mg L−1 malathion; T4: control diet + 1% TEO; T5: control diet + 0.025 mg L−1 malathion + 1% TEO and T6: control diet + 0.075 mg L−1 malathion + 1% TEO. After 21 days, T4 fish had the highest final body weight (FW), weight gain (WG), specific growth rate (SGR), and the lowest feed conversion ratio (FCR) among experimental treatments (P<0.05). The blood parameters including the red blood cells (RBC), white blood cell count (WBC), hematocrit (Hct), and hemoglobin (Hb) values were the highest in T4 treatment, displaying a significant difference with T1 treatment (P<0.05). Fish in the T4 groups had the highest total protein (TP) and albumin (ALB), while fish of T3 showed the lowest levels of these parameters (P<0.05) and also had the highest level of triglycerides (TRG), cholesterol (CHOL), lactate dehydrogenase (LDH), and urea (Ur). Alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) enzymes recorded the lowest levels in T4 treatment, which showed a significant difference with T1 group. The catalase (CAT) and superoxide dismutase (SOD) showed the highest activities in T4 treatment, while the lowest SOD and the highest malondialdehyde (MDA) levels occurred in T3 group (P<0.05). Total immunoglobulin (total Ig) level, alternative complement (ACH50) and lysozyme in the serum and skin mucus of T4 treatment of rainbow trout showed the highest activities with a significant difference from groups (P<0.05). From the results of the present study, it can be concluded that 1% of T. vulgaris as a supplement to the diet of rainbow trout can stimulate and improve the immune system of the fish. TEO can have a protective effect against unfavorable effects of malathion and improves the growth of the fish.

Magnetic nanoparticles-induced neurotoxicity and oxidative stress in brain of rainbow trout: Mitigation by ulexite through modulation of antioxidant, anti-inflammatory, and antiapoptotic activities

The prevalent exposition of metallic nanoparticles (MNPs) to the aquatic medium and their negative influence on human life is one of the major concerns global. Stress mechanization, as a non-specific and pervasive response, involves all physiological systems, particularly the closely interconnected neuroendocrine and immune systems. In this study, which was designed to obtain more data on the biological effects of ulexit, which prevents oxidative DNA damage by protecting against toxicity damage and offers new antioxidant roles. The concomitant use of ulexite (UX, as 18.75 mg/l) as a natural therapeutic agent against exposure to magnetic nanoparticles (Fe₃O₄-MNPs/0.013 ml/l) on Oncorhynchus mykiss was investigated for 96 h. The brain tissues were taken at the 48th and 96th hours of the trial period, the effects on neurotoxic, pro-inflammatory cytokine genes, antioxidant immune system, DNA and apoptosis mechanisms were analyzed. In the present study, it was determined that AChE activity and BDNF level in the brain tissue decreased over time in the Fe₃O₄-MNPs group compared to the control, and UX tried to depress this inhibition. While inhibition was determined in antioxidant system biomarkers (SOD, CAT, GPx, and GSH values), an induction was observed in lipid peroxidation indicators (MDA and MPO values) in Fe₃O₄-MNPs applied group. The same group data showed that TNF-α, IL-6, 8-OHdG and caspase-3 levels were increased, but Nrf-2 levels were decreased. The alterations in all biomarkers were found to be significant at the p < 0.05 level. In general, it was determined that Fe₃O₄-MNPs caused stress in O. mykiss and UX exhibited a positive effect on this stress management.

Insights on the Dynamics and Toxicity of Nanoparticles in Environmental Matrices

The manufacturing rate of nanoparticles (10–100 nm) is steadily increasing due to their extensive applications in the fabrication of nanoproducts related to pharmaceuticals, cosmetics, medical devices, paints and pigments, energy storage etc. An increase in research related to nanotechnology is also a cause for the production and disposal of nanomaterials at the lab scale. As a result, contamination of environmental matrices with nanoparticles becomes inevitable, and the understanding of the risk of nanoecotoxicology is getting larger attention. In this context, focusing on the environmental hazards is essential. Hence, this manuscript aims to review the toxic effects of nanoparticles on soil, water, aquatic, and terrestrial organisms. The effects of toxicity on vertebrates, invertebrates, and plants and the source of exposure, environmental and biological dynamics, and the adverse effects of some nanoparticles are discussed.

Ammonia in the presence of nano titanium dioxide (nano-TiO2) induces greater oxidative damage in the gill and liver of female zebrafish

Water pollution caused by a highly hazardous chemical ammonia and a widespread application nanomaterials-nano titanium dioxide (n-TiO₂) in nature water has attracted extensive concern of the world. However, the potential joint effects of the two factors are unknown. Aim to investigate the potential interactive effects of ammonia and n-TiO₂ and the behind mechanisms, adult female zebrafish (Danio rerio) were co-exposed for 8 weeks by total ammonia nitrogen (TAN; 0, 3, 30 mg/L) and n-TiO₂ (0, 0.1, 1 mg/L) in different combination conditions based on a full-factorial design. The analysis of absorption kinetics confirmed that n-TiO₂ could absorb free ammonia (NH₃) in aqueous solution and the loss rate of free NH₃ increased with the rise of n-TiO₂ concentration. Consistent with this, free NH₃ concentrations in the gill and liver were higher in the presence of n-TiO₂ compared to TAN exposure alone. The increases of MDA and PC concentrations in the gill and liver of fish indicated that TAN and n-TiO₂ alone or in combination caused oxidative stress. Simultaneously, the activity and transcription of antioxidant enzymes (T-SOD, CuZn-SOD, Mn-SOD, CAT, GPx and GST) as well as antioxidant GSH contents were extensively inhibited by TAN and n-TiO₂ via Nrf2-Keap1 signaling. The significant interactive effects of TAN and n-TiO₂ were detected on levels of GSH, GST and gstr1 mRNA in the gill, and on levels of GSH, T-SOD, Mn-SOD, CAT levels as well as gpx1a and keap1 mRNAs in the liver, implying synergistic toxic risk of TAN and n-TiO₂. The more severe histopathological alterations and higher IBR analysis in co-treatment groups further proved that the existence of n-TiO₂ excavated ammonia-induced toxicity in the gill and liver, especially in liver. In conclusion, ammonia and n-TiO₂ have a synergistic toxic risk of fish health because ammonia and n-TiO₂ cause oxidative-antioxidative imbalance by inducing ROS overproduction.

The effects of dietary exposure to Magnéli phase titanium suboxide and titanium dioxide on rainbow trout (Oncorhynchus mykiss)

Magnéli phase titanium suboxides (Magnéli TiO_x) are promising, novel materials with superior properties compared to TiO₂, they are substoichiometric titanium oxides with the chemical formula Ti_nO_2n-1 (where n ≥ 1). In this study, for the first time, subchronic effects of dietary intake of Magnéli TiO_x were evaluated and compared with TiO₂ particles of similar size, in concentrations 0.1% and 0.01% of feed. The experiment consisted of 38 d of an exposition period and 14 d of a depuration period. Minor effects on plasma biochemical profile and morphological parameters were recorded. A reduced count of leukocytes was found in the blood of both Magnéli TiO_x and TiO₂ exposed fish, suggesting immunotoxic effects. Erythrocytosis was specific for Magnéli TiO_x. Indices of oxidative stress, namely increased lipid peroxidation in liver, increased activity of superoxide dismutase in liver, kidney and gills and glutathione S-transferase (GST) in gills, as well as decreased activity of ceruloplasmin and GST in liver were found predominantly in fish exposed to TiO₂. Histopathological examination revealed increased lipid-like vacuolation in the liver, the presence of hyaline droplets in renal tubules and multiplication of mucous glands in the epidermis in both tested substances and intestine damage in TiO₂ groups. Overall, in Magnéli TiO_x exposed groups, fewer adverse effects compared to TiO₂ expositions were recorded. Their wider practical implementation in place of TiO₂ is therefore beneficial.

Bioaccumulation and depuration of TiO2 nanoparticles by zebrafish through dietary exposure: Size- and number concentration-resolved analysis using single-particle ICP-MS

The bioaccumulation and depuration of TiO₂ nanoparticles (TiO₂NPs) by zebrafish via the dietary exposure following the OECD Test Guideline 305 (OECD TG305) was evaluated using particle size- and number concentration-resolved analysis based on single-particle ICP-MS (spICP-MS). We found that using enzymatic digestion without H₂O₂ or excessive heating can recover 84.0 ± 4.0% and 94.5 ± 3.5% of TiO₂NP mass and number concentrations from fish tissue, respectively, without altering the size distribution of parent TiO₂NPs. OECD TG305 can allow for the evaluation of bioaccumulation and depuration of TiO₂NPs by fish based on the particle mass and number dose metrics. The toxicokinetic modeling can reasonably describe the mass- and number-based measurement data with the derived absorption efficiency α at ~0.2, depuration rate at ~0.5 d^-1, and kinetic biomagnification factor (BMF_k) at ~0.007 comparable with available data. The mass concentration- and number concentration-based bioaccumulation metrics including body burdens are correlated for TiO₂NPs that remained nano-sized in vivo and exhibited marginal physicochemical alterations upon uptake by fish. The result indicates that the traditional mass concentration metric may be used to represent the fish bioaccumulation potential for chemically inert NPs like TiO₂.

Protective effects of dietary Lavender (Lavandula officinalis) essential oil against Malathion-induced toxicity in rainbow trout (Oncorhynchus mykiss)

The present study was aimed to evaluate the moderating properties of Lavender (Lavandula officinalis) essential oil (LEO) against immunotoxic effects of the organophosphate pesticide, malathion in rainbow trout, Oncorhynchus mykiss. For this purpose, fish were supplemented with LEO at dietary concentrations of 0.5, 1, 2 and 4 ml/kg diet LEO for 56 days. A non-LEO supplemented group was also considered as control. After 57 days feeding trial, biochemicals were assayed in the blood and kidney tissue and then fish exposed to a sub-lethal concentration of malathion [0.24 mg/l equal to 30% of LC50 (0.8 mg/L)]. After 57 days feeding trial, the serum total immunoglobulin, respiratory burst activity, lysozyme activity and complement activity significantly elevated in fish treated with 1 and 2 ml LEO/kg diet compared to non-LEO supplemented individuals (P<0.01). Such changes were not observed in non-LEO supplemented fish (P>0.01). Significant elevations were observed in the expression of the immune genes (iNOS and C3 genes) in fish treated with 0.2–2 mg LEO/kg diet compared to non-supplemented ones (P<0.01). The lysozyme and complement activity significantly decreased in fish fed 4 ml/kg diet (P<0.01). After exposure to malathion, all immune components significantly declined in control and those treated with 0.5, 1 and 4 ml LEO/kg diet (P<0.01). In contrast, the immunity components exhibited no significant changes in fish treated with 2 ml LEO/kg diet after exposure (P>0.01). The expression of iNOS and C3 genes significantly reduced in control and fish fed 0.5, 1 and 4 ml LEO/kg diet in response to malathion (P<0.05). Furthermore, the expression of these genes showed no significant changes in fish fed with 2 ml LEO/kg diet after exposure (P>0.01). The findings of the present study suggested an immunoprotective role for dietary LEO at optimized dietary concentrations of 1 and 2 ml LEO/kg diet against oxidative stress and toxicity induced by malathion. Nevertheless, LEO at high dietary concentration (4 ml/kg diet) had reducing effects on the fish immunity.

Immunotoxic effects of metal-based nanoparticles in fish and bivalves

There is a global research interest in metal nanoparticles (MNPs) due to their diverse applications, rapidly increasing use, and increased presence in the aquatic environment. Currently, most MNPs in the environment are at levels unlikely to cause overt toxicity. Sub-lethal effects that MNPs may induce, notable immunotoxicity, could however have significant health implications. Thus, deciphering the immunological interactions of MNPs with aquatic organisms constitutes a much-needed area of research. In this article, we critically assess the evidence for immunotoxic effects of MNPs in bivalves and fish, as key wildlife sentinels with widely differing ecological niches that are used as models in ecotoxicology. The first part of this review details the properties, fate, and fundamental physicochemical behavior of MNPs in the aquatic ecosystem. We then consider the toxicokinetics of MNP uptake, accumulation, and deposition in fish and bivalves. The main body of the review then focuses on immune reactions in response to MNPs exposure in bivalves and fish illustrating their immunotoxic potential. Finally, we identify major knowledge gaps in our current understanding of the implications of MNPs exposure for immunological functions and the associated health consequences for bivalves and fish, as well as the general lessons learned on the immunotoxic properties of the emerging class of nanoparticulate contaminants in fish and bivalves.

Acute Exposure to Biogenic Nanosilver Produced from Fusarium oxysporum in a Neotropical Fish

Biogenic nanosilver (bNAg) has emerged as a potentially less toxic alternative to synthetic nanosilver. However, no studies have evaluated its effects on a fish species from the Neotropical region. Thus, our aim was to evaluate the effects of a bNAg on the Neotropical fish Prochilodus lineatus. For this purpose, after 24 h of exposure to 100 µg L^-1 of bNAg, blood samples were collected to evaluate hematological, genotoxic, and plasma parameters. Gills and liver were sampled to evaluate biomarkers of oxidative stress and brain samples were used to assess neurotoxicity. The fish presented hyperglycemia, an increased number of erythrocytes, a reduction in antioxidant enzyme activity in both tissues evaluated, and a decrease in lipid peroxidation in the gills. We concluded that P. lineatus is a sensitive species to this nanoparticle, since it presented alterations in several biomarkers after an acute exposure.

Effects of Se nanoparticles supplementation on growth performance, hematological parameters and nutrient digestibility of Labeo rohita fingerling fed sunflower meal based diet

The aim of the present study is to assess the effects of selenium nanoparticles on the growth, hematology and nutrients digestibility of Labeorohita fingerlings. Fingerlings were fed with seven isocaloric sunflower meal-based diet supplemented with different concentrations of nanoparticles naming T1 to T7 (0, 0.5, 1, 1.5, 2, 2.5, and 3 mg/kg), with 5% wet body weight while chromic oxide was used as an indigestible marker. After experimentation for 90 days T3 treated group (1mg/kg -1Se-nano level) showed the best result in hematological parameters (WBC's 7.97 ×103mm-3, RBC's 2.98 ×106 mm-3 and Platelet count 67), nutrient digestibility (crude protein: 74%, ether extract: 76%, gross energy: 70%) and growth performance (weight gain 13.24 g, weight gain% 198, feed conversion ratio 1.5, survival rate 100%) as compared to the other treatment groups. Specific growth rates were found significantly higher in T5 than in other groups. The present study indicated positive effect of 1 mg/kg Se-nanoparticles on growth advancement, hematological parameters, and nutrients digestibility of L. rohita fingerlings.

Dietary effects of a low-molecular weight fraction (<10 kDa) from shrimp waste hydrolysate on growth performance and immunity of rainbow trout (Oncorhynchus mykiss): Employing nanodelivery systems

Aquaculture by-products have been of great interest for producing protein hydrolysates with multiple biological activities. The present experiment was carried out to evaluate dietary effects of a low-molecular fraction (<10 kDa) from shrimp waste hydrolysate in forms of unprotected and nanocapsulated on growth and immunity of rainbow trout. Therefore, six diets were designed including a control diet (no supplementation), D1 (1 g kg^-1 of unprotected fraction), D2 (1 g kg^-1 chitosan nanocapsules), D3 (1 g kg^-1 liposome nanocapsules), D4 (1 g kg^-1 of fraction-loaded chitosan nanocapsules), D5 (1 g kg^-1 of fraction-loaded liposome nanocapsules). Fish (0.91 ± 0.15 g) were fed with experimental diets until apparent satiation for six weeks followed by a 5-day experimental challenge with Streptococcus iniae. Results revealed that growth is strongly affected in fish receiving the fraction with D4 treatment showing the highest weight gain, SGR, final weight and the lowest FCR (p < 0.05). Nanocapsules without fraction did not show remarkable effects when compared to control group. In terms of serum and mucus immune parameters of lysozyme, complement activity, myeloperoxidase activity, and total protease, fish from D4 group showed the highest measured values followed by D5 (p < 0.05). Key immune related genes of IL-6 and TNF-α were noticeably up-regulated in fish from D1, D4, and D5 groups, which were consistent with survival rate after 5 days challenge with Streptococcus iniae. All together, the present findings highlighted the application of chitosan and liposome nanocarriers in aquaculture and potential of low-molecular weight fraction (<10 kDa) from shrimp wastes hydrolysate to improve growth performance and immune status of rainbow trout.

Toxicity and deleterious impacts of selenium nanoparticles at supranutritional and imbalance levels on male goldfish (Carassius auratus) sperm

BACKGROUND

Selenium has a major role in male reproduction and antioxidative mechanisms. Although deficiency of this element can result in damages to the body's organs, this metalloid can induce deleterious effects in organisms by causing oxidative stress. This study assessed the spermatotoxicity of selenium nanoparticles (SeNPs) in goldfish (Carassius auratus) based on genotoxicity, antioxidant status, sperm quality, and histopathology.

METHODS

The fish with an average weight of 70 g (n = 288) were divided into four experimental groups (three replicates) and fed three times a day with SeNPs at different levels of 0, 0.1, 0.5, and 1 mg kg diet for 30 and 60 days.

RESULTS

After 30 and 60 days of feeding trial, compared to the control group, spermatocrit percentage markedly decreased at 1 mg kg SeNPs on day 30 as well as at 0.5 and 1 mg kg on day 60 (p < 0.05). Computer-assisted sperm analysis parameters especially VCL, VSL, and VAP decreased in response to SeNPs (p < 0.05). Percentage of fast speed progressive sperm cells was highest in fish fed with 0.1 mg kg SeNPs following the dietary experiment and significantly reduced in a SeNPs dose-dependent manner (p < 0.05). In addition, the levels of Malondialdehyde and Glutathione peroxidase were significantly elevated in seminal plasma of all SeNPs-treated groups (p < 0.05). On day 60, DNA damage of sperm was greatly increased at 1 mg kg SeNPs (p < 0.05). Moreover, the highest percentage of spermatocyte and spermatid were observed at the highest dose of SeNPs while the highest percentage of spermatozoa was recorded at the lowest and moderate SeNPs doses.

CONCLUSION

These findings suggested that non-optimal doses of SeNPs could reduce sperm quality, induce oxidative stress, and DNA damage in sperm, and disrupt testis development.

Evaluation of potential immunotoxic effects of iron oxide nanoparticles (IONPs) on antioxidant capacity, immune responses and tissue bioaccumulation in common carp (Cyprinus carpio)

Nanoparticles can be toxic and put human and animals' life at risk. The present work was carried out to evaluate the possible immunosuppressive effects of water borne iron oxide nanoparticles (IONPs) and the FeCl₃ on immune components of common carp (Cyprinus carpio). Fish were exposed to a series of chronic levels of 25%, 50%, and 75% of IONPs LC₅₀ 96 h concentration (referred to as control, NP1, NP2, and NP3 respectively) or FeCl₃ (same concentrations as IONPs referred to as S1, S2, and S3 respectively) for 21 days. Results revealed alterations in blood parameters, where IONPs significantly decreased number of white blood cells at all concentrations. Glucose and cortisol increased in all exposed fish after 21 days, suggesting activation of the maintenance mechanism cascade against a chronic stressor. IONPs or FeCl₃ significantly accumulated in liver tissue of exposed fish. Immune responses were remarkably decreased in serum and skin mucus in response to IONPs or FeCl₃. These components were at lowest levels in fish exposed to the highest concentrations of IONPs and FeCl₃. The findings of the present study suggested that IONPs is accumulated in fish liver and intestine, where they may exhibit immunotoxicity.

Mild Effects of Sunscreen Agents on a Marine Flatfish: Oxidative Stress, Energetic Profiles, Neurotoxicity and Behaviour in Response to Titanium Dioxide Nanoparticles and Oxybenzone

UV filters are potentially harmful to marine organisms. Given their worldwide dissemination and the scarcity of studies on marine fish, we evaluated the toxicity of an organic (oxybenzone) and an inorganic (titanium dioxide nanoparticles) UV filter, individually and in a binary mixture, in the turbot (Scophthalmus maximus). Fish were intraperitoneally injected and a multi-level assessment was carried out 3 and 7 days later. Oxybenzone and titanium dioxide nanoparticles induced mild effects on turbot, both isolated and in mixture. Neither oxidative stress (intestine, liver and kidney) nor neurotoxicity (brain) was found. However, liver metabolic function was altered after 7 days, suggesting the impairment of the aerobic metabolism. An increased motility rate in oxybenzone treatment was the only behavioural alteration (day 7). The intestine and liver were preferentially targeted, while kidney and brain were unaffected. Both infra- and supra-additive interactions were perceived, with a toxicodynamic nature, resulting either in favourable or unfavourable toxicological outcomes, which were markedly dependent on the organ, parameter and post-injection time. The combined exposure to the UV filters did not show a consistent increment in toxicity in comparison with the isolated exposures, which is an ecologically relevant finding providing key information towards the formulation of environmentally safe sunscreen products.

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.

Tinospora cordifolia ameliorated titanium dioxide nanoparticle-induced toxicity via regulating oxidative stress-activated MAPK and NRF2/Keap1 signaling pathways in Nile tilapia (Oreochromis niloticus)

Titanium dioxide nanoparticle (TNP) has been suggested for use in fish farms to prevent or alleviate bacterial diseases owing to its bactericidal property. Unfortunately, the interaction of TNP with cells impaired the host defenses of fish resulting in increased mortality during bacterial challenges. The present study evaluated the efficacy of the ethanolic extract of Tinospora cordifolia (TCE) as a dietary supplement in ameliorating TNP induced toxicity in Nile tilapia (Oreochromis niloticus). The fishes were exposed to environmentally relevant concentration (10 mg/L) of TNP for 14 days and the effect of TCE supplemented feed at 3 different doses (5, 10, and 15 g/kg) was studied. TCE signally increased the weight gain, specific growth rate, and decreased feed conversion ratio in fish. TCE significantly (P < 0.05) ameliorated the toxic effects caused by TNP by increasing the antioxidant (CAT, SOD, GPx) activity and decreasing the levels of serum enzymes (ALT, AST, ALP, ACP), macromolecular oxidation, excessive ROS production, and pro-inflammatory cytokines (IL-1β, IL-6, IL-8, INF-γ, TNF-α, PGE-2). TNP bioaccumulation and histopathological alterations in gill, liver, and kidney were also significantly alleviated by TCE supplementation. TCE perceptibly regulated the expression of heat shock proteins (HSP60, -70), MAPKs (pERK1/2, pp38), antioxidant (NRF2, Keap1, HO-1), apoptotic (p53, PDRG1), and anti-apoptotic (AKT, Bcl2) proteins in fish. Regarding disease resistance, the TCE co-treated groups showed reduced cumulative mortality and higher relative percent survival with A. hydrophila. Our results suggest that TNP-induced apoptosis is mediated by the MAPK/NRF2/Keap1 pathway and underlines the therapeutic potential of TCE in aqua-farming.

Sunscreens: UV filters to protect us: Part 2-Increasing awareness of UV filters and their potential toxicities to us and our environment

BACKGROUND

Sunscreens are topical preparations containing one or more compounds that filter, block, reflect, scatter, or absorb ultraviolet (UV) light. Part 2 of this review focuses on the environmental, ecological effects and human toxicities that have been attributed to UV filters.

METHODS

Literature review using NIH databases (eg, PubMed and Medline), FDA and EPA databases, Google Scholar, the Federal Register, and the Code of Federal Regulations (CFR).

LIMITATIONS

This was a retrospective literature review that involved many different types of studies across a variety of species. Comparison between reports is limited by variations in methodology and criteria for toxicity.

CONCLUSIONS

In vivo and in vitro studies on the environmental and biological effects of UV filters show a wide array of unanticipated adverse effects on the environment and exposed organisms. Coral bleaching receives considerable attention from the lay press, but the scientific literature identifies potential toxicities of endocrine, neurologic, neoplastic and developmental pathways. These effects harm a vast array of aquatic and marine biota, while almost no data supports human toxicity at currently used quantities (with the exception of contact allergy). Much of these data are from experimental studies or field observations; more controlled environmental studies and long-term human use data are limited. Several jurisdictions have prohibited specific UV filters, but this does not adequately address the dichotomy of the benefits of photoprotection vs lack of eco-friendly, safe, and FDA-approved alternatives.

Multi-biomarker approach to assess the acute effects of cerium dioxide nanoparticles in gills, liver and kidney of Oncorhynchus mykiss

Cerium oxide nanoparticles (CeO₂-NP) have already been detected in the aquatic compartment, however, the evaluation of potential ecotoxicological effects on biota are scarce. The present study aimed to assess the toxic effects of CeO₂-NP in Oncorhynchus mykiss in different organs/tissues (gills, liver and kidney) after acute exposure (96 h) to three concentrations: 0.25, 2.5 and 25 mg/L. Oxidative stress response (catalase - CAT; glutathione S-transferases - GSTs), lipid peroxidation (thiobarbituric acid reactive substances - TBARS), Na⁺/K⁺-ATPase activity, genotoxicity (genetic damage index - GDI) and histopathology (organ's pathological indices) were evaluated. CAT activity was increased in gills and decreased in liver of fish exposed to the highest CeO₂-NPs concentration tested. However, GSTs and Na⁺/K⁺-ATPase activities and TBARS levels were not significantly altered in analysed organs. CeO₂-NP caused marked changes in the gills (aneurysms, blood capillary congestion, lamellar hypertrophy and hyperplasia, secondary lamella fusion and epithelial lifting), in liver (pyknotic nucleus, hyperemia, enlargement of sinusoids and leucocyte infiltration) and kidney (shrinkage of the glomeruli, enlargement of the Bowman space, tubular degeneration and nuclear hypertrophy). Moreover, a semi-quantitative histopathological scoring system (pathological index) confirmed significant alterations in the three organs of all exposed fish. Furthermore, a significant increase of GDI indices observed in gills and liver, for all tested concentrations, indicated a dose-dependent effect. The present study suggests that the release of CeO₂-NP into the aquatic environment promotes biochemical, genotoxic and histopathological damages in fish. However, the mechanisms underlying the occurrence of such effects require further investigation.

Transfer and Transcriptomic Profiling in Liver and Brain of European Eels (Anguilla anguilla) After Diet-borne Exposure to Gold Nanoparticles

A nanometric revolution is underway, promising technical innovations in a wide range of applications and leading to a potential boost in environmental discharges. The propensity of nanoparticles (NPs) to be transferred throughout trophic chains and to generate toxicity was mainly assessed in primary consumers, whereas a lack of knowledge for higher trophic levels persists. The present study focused on a predatory fish, the European eel (Anguilla anguilla) exposed to gold NPs (AuNPs; 10 nm, polyethylene glycol-coated) for 21 d at 3 concentration levels in food: 0 (NP0), 1 (NP1), and 10 (NP10) mg Au kg^-1 . Transfer was assessed by Au quantification in eel tissues, and transcriptomic responses in the liver and brain were revealed by a high-throughput RNA-sequencing approach. Eels fed at NP10 presented an erratic feeding behavior, whereas Au quantification only indicated transfer to intestine and kidney of NP1-exposed eels. Sequencing of RNA was performed in NP0 and NP1 eels. A total of 258 genes and 156 genes were significantly differentially transcribed in response to AuNP trophic exposure in the liver and brain, respectively. Enrichment analysis highlighted modifications in the immune system-related processes in the liver. In addition, results pointed out a shared response of both organs regarding 13 genes, most of them being involved in immune functions. This finding may shed light on the mode of action and toxicity of AuNPs in fish. Environ Toxicol Chem 2020;39:2450-2461. © 2020 SETAC.

Are Titania Photocatalysts and Titanium Implants Safe? Review on the Toxicity of Titanium Compounds

Titanium and its compounds are broadly used in both industrial and domestic products, including jet engines, missiles, prostheses, implants, pigments, cosmetics, food, and photocatalysts for environmental purification and solar energy conversion. Although titanium/titania-containing materials are usually safe for human, animals and environment, increasing concerns on their negative impacts have been postulated. Accordingly, this review covers current knowledge on the toxicity of titania and titanium, in which the behaviour, bioavailability, mechanisms of action, and environmental impacts have been discussed in detail, considering both light and dark conditions. Consequently, the following conclusions have been drawn: (i) titania photocatalysts rarely cause health and environmental problems; (ii) despite the lack of proof, the possible carcinogenicity of titania powders to humans is considered by some authorities; (iii) titanium alloys, commonly applied as implant materials, possess a relatively low health risk; (iv) titania microparticles are less toxic than nanoparticles, independent of the means of exposure; (v) excessive accumulation of titanium in the environment cannot be ignored; (vi) titanium/titania-containing products should be clearly marked with health warning labels, especially for pregnant women and young children; (vi) a key knowledge gap is the lack of comprehensive data about the environmental content and the influence of titania/titanium on biodiversity and the ecological functioning of terrestrial and aquatic ecosystems.

Effects of titanium dioxide nanoparticles on the intestine, liver, and kidney of Danio rerio

Titanium dioxide nanoparticles (Np-TiO₂) have become the common component of sunscreen cosmetic products. Np-TiO₂ can affect especially aquatic ecosystems health, including aquatic organisms such as fish. It is therefore necessary to acquire a better understanding of the effect of Np-TiO₂ on aquatic organisms. This study evaluated the biological effects of Np-TiO₂ on Danio rerio, such as survival rate and weight change and, in particular, the Ti content or retention in the intestine and liver, as well as the activities of catalase and superoxide dismutase enzymes. In addition, the structure of the intestine, kidney, and liver was investigated through histological analysis. Ninety zebrafish were used, randomly divided into three treatment-groups: a control group (fed with food without adding Np-TiO₂) and two groups of fish fed with food containing Np-TiO₂ exposed for 7 and 14 days. The amount of Ti in the liver and intestine was measured using atomic absorption spectrophotometry coupled to a graphite furnace (GFAAS). Morphological analysis and enzyme catalase and superoxide dismutase assays were likewise performed. Ti was detected in all fish even in control group; probably Ti must have been introduced during production by the fish food industry. Structural changes were detected in fish fed with Np-TiO₂ as vacuolization and disruption of the apical cytoplasm of epithelial cells that covered the intestinal villi. Although kidney morphology appeared intact, the lumen of the proximal tubule was enlarged, and the cells of the distal tubule were vacuolated. No morphological changes in the liver were detected; however, superoxide dismutase activity decreased, suggesting that liver changes occurred at the molecular level. Thus, Np-TiO₂ causes morphological changes in the intestine, kidney, and liver of zebrafish and biochemical changes in the liver exposed for 7 and 14 days. Although not highly lethal, Np-TiO₂ in the food chain can interfere with the morphophysiology of aquatic organisms. Neither mortalities nor body weight losses were recorded among fish in all groups over the duration of the experiment.

Exposure of rainbow trout (Oncorhynchus mykiss) to magnetite (Fe3O4) nanoparticles in simplified food chain: Study on ultrastructural characterization

The widespread exposure of metallic nanoparticles to the aquatic ecosystem and its adverse impact on human life is the colossal concern worldwide. In view of this, this context was investigated to analyze microscopically the bioaccumulation and localization of magnetite (Fe₃O₄) nanoparticles in the cellular organelles of rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) in aquatic conditions. Initially, Fe₃O₄ nanoparticles were absorbed on to Elodea (Elodea canadensis) and fed to molluscs (Melanopsis praemorsa). Fish were fed with the same molluscs, and then the intestines and liver were examined using light and transmission electron microscopy. Results showed that nanoparticles were present in the cytoplasm and other organelles of cells (mitochondrion and lysosome) by absorbing through microvilli of the epithelial cells of the tunica mucosa in the intestine. Further, nanoparticles passed through the vessels of the lamina propria of the tunica mucosa and reached to the sinusoids of the liver via blood circulation. It was then accumulated from the endothelium of the sinusoid to the cytoplasm of liver hepatocytes and to mitochondria and lysosome. The accumulation of nanoparticles in the epithelial cells, cytoplasm, mitochondria, and lysosome revealed the degree of transparency of the pattern with slight hesitation. In summary, this investigation contributed towards the understanding of the physiological effects of Fe₃O₄ nanoparticles on O. mykiss, which ascertains essentiality for sustainable development of nanobiotechnology in the aquatic ecosystem.

Titanium dioxide nanoparticles-induced cytogenotoxicity and alterations in haematological indices of Clarias gariepinus (Burchell, 1822)

The application of titanium dioxide (TiO₂) nanoparticles (NPs) in the manufacturing of consumer products has increased tremendously and with the potential to induce deleterious effects on aquatic biota. There have been reports on metal oxide NP toxicity in aquatic organisms, however, information on cytotoxicity and genotoxicity of TiO₂ NPs on the African catfish, Clarias gariepinus, is scarce. In this study, we investigated the genotoxicity and haematotoxicity of TiO₂ NPs in C. gariepinus using the micronucleus (MN) assay and haematological analysis, respectively. Juvenile C. gariepinus were exposed to 6.25, 12.5, 25.0, 50.0 and 100.0 mg L^-1 concentrations of TiO₂ NPs for 7 and 28 days. Benzene (0.05 mL L^-1) and dechlorinated tap water were used as positive and negative controls, respectively. Data of the MN showed a significant (p < 0.05) concentration-dependent increase in the frequency of MN at both exposure periods in comparison to negative control. Red blood cells, haematocrit, platelets and heterophils significantly reduced with an increased mean corpuscular haemoglobin concentration and lymphocytes at the 7-day exposure period, while in the 28-day exposure period, mean cell volume, mean corpuscular haemoglobin and lymphocytes had a significant increase in comparison with the negative control. This study indicates that TiO₂ NPs induced cytogenetic and haematological alterations in C. gariepinus and is of relevance in biodiversity and aquatic health management.

Chronic effects of wastewater-borne silver and titanium dioxide nanoparticles on the rainbow trout (Oncorhynchus mykiss)

Even though nanoparticles (NPs) are mostly removed by wastewater treatment plants, wastewater-borne NPs may show an altered toxicity to aquatic organisms. The main objectives of this work were: i) to assess the chronic (28 days) effects of wastewater-borne NPs of silver (AgNPs, 1.4-36.2 μg L^-1) and titanium dioxide (TiO₂NPs, 3.1-50.2 μg L^-1) at the individual (growth) and biochemical (biomarkers of neurotoxicity, oxidative stress and energy metabolism) levels in rainbow trout Oncorhynchus mykiss; and ii) to compare them with their effluent-supplemented and water-dispersed counterparts. The total Ag and Ti levels were determined in several fish organs. The growth of O. mykiss was not affected by the NPs in any treatment, except a 29% increase at 5.5 μg L^-1 of total Ag supplemented to effluents. The Ag level in organs of O. mykiss was significantly higher after exposure to water-dispersed AgNPs than their wastewater-borne or effluent-supplemented counterparts. No significant Ti uptake could be observed. Effluent-supplemented TiO₂NPs (50.1 μg L^-1 Ti) potentially induced neurotoxic effects, indicated by a 24% increase in acetylcholinesterase activity comparatively to controls. Energy reserves were unaffected by TiO₂ treatments, while nearly all AgNP-containing treatments caused a depletion of total lipids, proteins and carbohydrates in the muscle, suggesting an increased energy demand for detoxification processes to cope with AgNPs. Besides NPs, the effluent matrix and dispersing agent (for AgNPs) induced significant effects on energetic reserves and oxidative stress, indicating background toxicity of both treatments at the biochemical level. Our study is the first to assess chronic effects of wastewater-borne NPs on rainbow trout. While no effects were found at the individual level, several biochemical markers were changed by the NPs exposure. Our results highlight the importance of using complex matrices for a reliable risk assessment of NPs in the aquatic environment.

Dietary exposure to polyvinyl chloride microparticles induced oxidative stress and hepatic damage in Clarias gariepinus (Burchell, 1822)

The present study investigated the effects of polyvinyl chloride (PVC) microparticles (MP) on hepatic antioxidant enzymes activities, serum biochemical and liver histology of juvenile Clarias gariepinus. A total of 180 (25.15 g average weight) C. gariepinus were fed PVC MP (95.41 ± 4.23 μm) spiked diets at 0.5, 1.5, 3.0 percentage inclusion levels and a control diet for 45 days of exposure, then followed by 30 days of depuration trials. Fish specimens (9) from each treatment were sampled every 15-day interval for serum biochemical, liver antioxidant enzymes and histopathological assay. Glucose and triglyceride levels increased significantly in PVC-treated groups when compared with the control. Protein levels of 0.5% and 3.0% PVC-treated groups reduced significantly on the 15th and 30th day exposure periods, while serum enzyme activities of all PVC-treated groups increased significantly in a time-dependent manner. Antioxidant enzymes (superoxide dismutase, glutathione peroxidase, catalase) activity in the liver of the treated groups also decreased progressively in a time-dependent manner. A time-dependent elevation in lipid peroxidation levels was observed in PVC MP-treated groups. Histopathological assessment of the fish liver showed mild to severe levels of glycogen depletion, fatty vacuolation and degeneration, hepatocellular necrosis in PVC-treated groups with reference to the control. The present study revealed that PVC microplastic induced oxidative damage and hepatic histopathological alterations in the exposed fish.

Sex-dependent and organ-specific toxicity of silver nanoparticles in livers and intestines of adult zebrafish

Silver nanoparticles (AgNPs) have been increasingly manufactured and thus are increasingly detected in aquatic systems. However, there are still some overlooked factors (e.g., organism sex) in the field of nano-toxicological assessment. In this study, to explore the role of sex in nanotoxicity, adult male and female zebrafish were exposed to 100 μg/L of two uncoated commercial AgNPs with primary sizes 20 nm and 80 nm for 2 weeks, after which the impacts of AgNPs on intestines and livers of both male and female zebrafish were assessed using a suite of biomarkers. Results demonstrated that the intestinal Na/K-ATPase activity as well as the superoxide dismutase activity in male zebrafish differed significantly between 20-nm AgNPs and 80-nm AgNPs treatments (p < 0.05), indicating 20-nm AgNPs showing higher toxicity to zebrafish than the 80-nm AgNPs. Also, we noted that the used AgNPs induced sex-dependent effects on growth indices, oxidative/anti-oxidative status, neural signaling and hepatic lipid metabolism, with the male zebrafish being more sensitive to AgNPs than the females. Further, the tested AgNPs impaired the intestine much more seriously than the liver, as evidenced by the disruptions of Na/K-ATPase and antioxidant system in intestine but not in liver. These findings imply that prolonged exposure to AgNPs might induce size-related, sex-dependent, and organ-specific toxicity to adult zebrafish, thereby may significantly extend our understanding of the toxic effects of AgNPs in aquatic environment.

Bioaccumulation, biodistribution，and depuration of 13C-labelled fullerenols in zebrafish through dietary exposure

In aquatic organisms, dietary exposure to nanomaterials is not only one of the important uptake pathways, but it is also one method to assess the transmission risk of the food chain. To address this concern, we quantitatively investigated the accumulation and depuration of fullerenols in the tissues of zebrafish after exposure to fullerenols-contaminated Daphnia magna. After exposure to ¹³C-labelled fullerenol solution at a concentration of 2.5 mg/L for 72 h, the steady state concentration of fullerenols in D. magna was 31.20 ± 1.59 mg/g dry weight. During the 28 d uptake period for zebrafish, fullerenols in the tissues increased in a tissue- and day-dependent manner, and the major target tissues of fullerenols were the intestines and liver, followed by the gill, muscle, and brain. The kinetic parameters of uptake and depuration were also quantitatively analyzed. After depuration for 15 d, a certain amount of residual fullerenols remained in the tissues, especially the brain, where approximately 64 d may be needed to achieve 90% of the cumulative concentration depuration. The calculated distribution-based trophic transfer factors (TTF_d values) (from 0.26 to 0.49) indicated that the tissue biomagnification of fullerenols by zebrafish through dietary exposure may not occur. Transmission electron microscopy (TEM) confirmed the presence of fullerenols in D. magna and the tissues of zebrafish. Our research data are essential for thoroughly understanding of the fate of nanoparticles through the dietary exposure pathway and directing future tissue bioeffect studies regarding target tissues for further research.

Synergistic effect of zinc nanoparticles and temperature on acute toxicity with response to biochemical markers and histopathological attributes in fish

In the present study, an experiment was carried out to delineate the lethal concentration of (LC₅₀) zinc nanoparticles (Zn-NPs) alone and with concurrent to high temperature (34 °C) in Pangasianodon hypophthalmus. The lethal concentration of Zn-NPs alone and with high temperature was estimated as 21.89 and 19.74 mg/L respectivey in P. hypophthalmus. The lethal concentration was decided with the help of definite concentration via 16, 18, 20, 22, 24, 26, 28 and 30 mg/L. The Zn-NPs were significantly alter the biochemical and histopathology of different fish tissues. The stress biomarkers such as oxidative stress (catalase superoxide dismutase and glutathione-s-transferase, lipid peroxidation) was studied in the liver, gill and kidney tissue, which was noticeable (p < 0.01) enhanced with higher concentration in both condition (Zn-NPs alone and Zn-NPs-T) in dose dependent manners. The carbohydrate (lactate dehydrogenase and malate dehydrogenase) and protein metabolic enzymes (alanine amino transferase and aspartate amino transferase) were also remarkable enhanced (p < 0.01) with higher concentration of Zn-NPs and Zn-NPs-T. The neurotransmitter (acetylcholine esterase) activities were significant inhibited (p < 0.01) with exposure to Zn-NPs and Zn-NPs-T and digestive enzymes such as protease and amylase were non-significant (p > 0.01) with the exposure of Zn-NPs and Zn-NPs-T, further, lipase were significantly reduced (p < 0.01) with exposure to Zn-NPs and temperature exposure group. The histopathological alteration were also observed in the liver and gill tissue. The present investigation suggested that, essential trace elements at higher concentration in acute exposure led to pronounced deleterious alteration on histopathology and cellular and metabolic activities in fish.

Comparative toxicity of nanoparticulate and ionic copper following dietary exposure to common carp (Cyprinus carpio)

Copper is an essential element for the normal growth and survival of all organisms including fish. However, its excessive presence in the environment can cause bioaccumulation and aquatic toxicology. The aim of the present study was to compare the dietary toxicity effects of two different Cu compounds, copper oxide nanoparticles (CuO-NPs) and ionic copper (CuSO₄) in juvenile common carp, Cyprinus carpio. To prepare experimental diets, two nominal concentrations of 100 and 1000 mg Cu kg^-1 diet were added to a basal diet. Carp (n = 450, average initial weight of 35.94 ± 5.35 g) were fed on the Cu-supplemented diets and basal diets for two 21-day courses as dietary exposure and recovery periods, respectively. The growth performance, survival rate and blood biochemical indices as well as copper accumulation in target organs of fish were investigated at the end of each exposure period. The results showed that the weight gain (WG) of carp significantly decreased coincident with increasing concentration of the both dietary Cu forms (P = 0.00). Both Cu sources at concentrations of 100 mg kg^-1 diet decreased the survival rate of fish (P = 0.003), likely due to more feed intake and thus increased copper toxicity. The both forms of dietary Cu at two different concentrations significantly decreased the plasma glutamate oxaloacetate transaminase (GOT) level compared to the control group (P = 0.008). Fish exposed to diets containing Cu sources except 100 mg Cu kg^-1 of CuO-NPs showed the lower glutamate pyruvate transaminase (GPT) activity in comparison to the control (P = 0.00). The plasma sodium level in1000 mg CuO-NPs kg^-1 diet was significantly lower than the control (P = 0.001). The plasma potassium level increased in the all Cu-supplemented groups except 100 mg kg^-1 of CuO-NPs after the dietary exposure period (P = 0.035). The copper accumulation was dose-dependent in all target organs. In 100 mg Cu kg^-1 dietary groups, the liver showed the highest Cu accumulation (P = 0.00), while in 1000 mg Cu kg^-1 dietary groups, the highest Cu content was observed in the intestine (P = 0.00). The results demonstrated the enhanced toxicological responses in fish after 21 days of dietary exposure, but the levels of most of biochemical indices and tissues Cu content decreased or returned to the control values after the recovery period.

Estimating human exposure to titanium dioxide from personal care products through a social survey approach

Titanium dioxide (TiO₂ ) has been widely applied in personal care products (PCPs), with up to 36% of TiO₂ in PCPs is present at the nanoscale. Due to the large quantity produced and the wide application of TiO₂ , there is a great potential for human exposure through various routes and therefore a great potential to elicit adverse impacts. This work utilizes a social survey to generate information and estimate TiO₂ (bulk and nanoparticle [NP]) exposure to individuals through the daily use of PCPs. Households in the Madison, Wisconsin, USA metropolitan area were surveyed about their PCP usage. Survey results were then combined with usage patterns and TiO₂ content in each PCP category to estimate human exposures. Results indicate sunscreen and toothpaste are major contributors to TiO₂ dermal exposure. The estimated daily dermal route of exposure ranges from 2.8 to 21.4 mg TiO₂ per person per day. Toothpaste has the potential to be ingested though the oral route; 0.15 to 3.9 mg TiO₂ per day were estimated to be ingested when 10% toothpaste ingestion was assumed. The results generated in the present case study are generalizable in predicting individual TiO₂ exposure from PCPs when the usage pattern is available. In addition, this study can be further used for risk assessment and to refine the use of TiO₂ in PCPs. Integr Environ Assess Manag 2019;00:1-7. © 2019 SETAC.

Advances on assessing nanotoxicity in marine fish - the pros and cons of combining an ex vivo approach and histopathological analysis in gills

The need to overcome logistic and ethical limitations of in vivo nanotoxicity evaluation in marine organisms is essential, mostly when dealing with fish. It is well established that medium/solvent conditions affect dispersion and agglomeration of nanoparticles (NPs), which represents a constraint towards a solid and realistic toxicity appraisal. In this way the pros and cons of an ex vivo approach, using a simplified exposure medium (seawater) and addressing gills histopathology, were explored. The nanotoxic potential of environmentally realistic concentrations of titanium dioxide NPs (TiO₂ NPs) was also assessed, disclosing the morpho-functional effects on the gills and the possible uptake/elimination processes. Excised gills of the Senegalese sole (Solea senegalensis) were directly exposed in artificial seawater to 20 and 200 μg L^-1 TiO₂ NPs, for 2 h and 4 h. Semi-quantitative and quantitative histological analyses were applied. The normal morphology of the gill's epithelia was only slightly altered in the control, reflecting protective mechanisms against the artificiality of the experimental conditions, which, together with the absence of differences in the global histopathological index (I_h), corroborated that the gill's morpho-functional features were not compromised, thereby validating the proposed ex vivo approach. TiO₂ NPs induced moderate severity and dissemination of histopathological lesions. After 2 h, a series of compensatory mechanisms occurred in NP treatments, implying an efficient response of the innate defense system (increasing number of goblet cells) and effective osmoregulatory ability (chloride cells proliferation). After 4 h, gills revealed signs of recovery (normalization of the number of chloride and goblet cells; similar I_h), highlighting the tissue viability and effective elimination and/or neutralization of NPs. The uptake of the TiO₂ NPs seemed to be favored by the higher particle sizes. Overall, the proposed approach emerged as a high-throughput, reliable, accurate and ethically commendable methodology for nanotoxicity assessment in marine fish.

Mechanoregulation of titanium dioxide nanoparticles in cancer therapy

Titanium dioxide (TiO₂) nanoparticles (NPs), first developed in the 1990s, have been applied in numerous biomedical fields such as tissue engineering and therapeutic drug development. In recent years, TiO₂-based drug delivery systems have demonstrated the ability to decrease the risk of tumorigenesis and improve cancer therapy. There is increasing research on the origin and effects of pristine and doped TiO₂-based nanotherapeutic drugs. However, the detailed molecular mechanisms by which drug delivery to cancer cells alters sensing of gene mutations, protein degradation, and metabolite changes as well as its associated cumulative effects that determine the microenvironmental mechanosensitive metabolism have not yet been clearly elucidated. This review focuses on the microenvironmental influence of TiO₂-NPs induced various mechanical stimuli on tumor cells. The differential expression of genome, proteome, and metabolome after treatment with TiO₂-NPs is summarized and discussed. In the tumor microenvironment, mechanosensitive DNA mutations, gene delivery, protein degradation, inflammatory responses, and cell viability affected by the mechanical stimuli of TiO₂-NPs are also examined.

FTIR study of the binary effect of titanium dioxide nanoparticles (nTiO2) and copper (Cu2+) on the biochemical constituents of liver tissues of catfish (Clarias gariepinus)

•

The mixture of nanomaterial and essential metal is of concern for freshwater.

•

Co-exposure of titanium dioxide nanoparticles (nTiO₂) and copper (Cu²⁺) revealed.

•

Notable alteration of biochemical constituents and histopathology of liver tissues.

•

FTIR and histological techniques are adequate for the monitoring of changes in fish tissues.

The increasing demand for nanomaterials and essential metals leads to their discharge into the aquatic ecosystems through water run-off and this is of great concern for the aquatic biodiversity.

In the present study titanium dioxide nanoparticles (nTiO₂) and copper (Cu²⁺) effects in binary mixture on the biochemical constituents of the liver of Clarias gariepinus by using Fourrier- transform infrared (FT-IR) techniques was examined. The FT-IR revealed significant differences in absorbance intensities between the control and exposed liver tissues demonstrating changes on the critical biochemical constituents such as proteins, lipids and carbohydrates. This result further reveals the binary mixture responsible for the absence of CH₃ bending lipids in liver tissues due to their toxic effect. The observed synergistic decreasing ratio of integrated area (1545/3296) for binary mixture exposed liver tissues suggests that lipid degradation predominates over amide formation. In addition, binary mixture causes an alteration in protein secondary structures by decreasing the β turns of liver tissues. Histology in liver showed marked damages. The frequent alteration in the biochemical constituents in the liver tissues of C. gariepinus could be an indication of alteration of existing biochemical components or the expression of new components.

Mixture toxicity effects and uptake of titanium dioxide (TiO2) nanoparticles and 3,3',4,4'-tetrachlorobiphenyl (PCB77) in juvenile brown trout following co-exposure via the diet

Titanium dioxide nanoparticles (n-TiO₂) are among the man-made nanomaterials that are predicted to be found at high concentrations in the aquatic environment. There, they likely co-exist with other chemical pollutants. Thus, n-TiO₂ and other chemical pollutants can be taken up together or accumulate independently from each other in prey organisms of fish. This can lead to dietary exposure of fish to n-TiO₂-chemical pollutant mixtures. In this study, we examine if simultaneous dietary exposure to n-TiO₂ and 3,3',4,4'-Tetrachlorobiphenyl (PCB77) -used as a model compound for persistent organic pollutants with dioxin-like properties- can influence the uptake and toxicological response elicited by the respective other substance. Juvenile brown trout (Salmo trutta) were fed custom-made food pellets containing n-TiO_2, PCB77 or n-TiO₂+PCB77 mixtures for 15 days. Ti and PCB77 concentrations in the liver were measured by ICP-MS and GC-MS, respectively. Besides, n-TiO₂ uptake was assessed using TEM. Combination effects on endpoints specific for PCB77 (i.e., cytochrome P450 1A (CYP1A) induction) and endpoints shared by both PCB77 and n-TiO₂ (i.e., oxidative stress-related parameters) were measured in intestine and liver using RT-qPCR and enzyme activity assays. The results show that genes encoding for proteins/enzymes essential for tight junction function (zo-1) and ROS elimination (sod-1) were significantly upregulated in the intestine of fish exposed to n-TiO₂ and PCB77 mixtures, but not in the single-substance treatments. Besides, n-TiO₂ had a potentiating effect on PCB77-induced CYP1A and glutathione reductase (GR) expression/enzyme activity in the liver. This study shows that simultaneous dietary exposure to nanomaterials and traditional environmental pollutants might result in effects that are larger than observed for the substances alone, but that understanding the mechanistic basis of such effects remains challenging.

Effect of copper nanoparticles on brain cytochrome P450 enzymes in rats

The aim of the present study was to evaluate the long‑term effect of copper nanoparticles (CuNPs) on cytochrome P450 (CYP450) enzymes in the rat brain. Rats were repeatedly gavaged with different forms of copper sources for 28 days, and the levels of oxidative stress and CYP450 mRNA and protein expression in the rat brain were subsequently analyzed. The results demonstrated that a high dose of CuNPs (200 mg/kg) induced severe oxidative stress in the rat brain along with a decrease in the levels of total superoxide dismutase and glutathione, and an increase in hydroxyl radicals and malondialdehyde. A medium dose of CuNPs reduced CYP450 2C11 and CYP450 3A1 protein expression in the rat brain, whereas high doses of CuNPs resulted in decreased expression of most CYP450 enzyme proteins, and inhibition of pregnane X receptor and constitutive androstane receptor expression. The results suggested that CuNPs may inhibit CYP450 enzyme expression by increasing the levels of oxidative stress and decreasing the expression of nuclear receptors in the rat brain, which affects the metabolism of drugs and endogenous hormones in the brain.

Endocytosis, intracellular fate, accumulation, and agglomeration of titanium dioxide (TiO2) nanoparticles in the rainbow trout liver cell line RTL-W1

There is increasing evidence that titanium dioxide (TiO2) nanoparticles (NPs) present in water or diet can be taken up by fish and accumulate in internal organs including the liver. However, their further fate in the organ is unknown. This study provides new insights into the interaction, uptake mechanism, intracellular trafficking, and fate of TiO2 NPs (Aeroxide® P25) in fish liver parenchymal cells (RTL-W1) in vitro using high-resolution transmission electron microscopy (TEM) and single particle inductively coupled plasma mass spectrometry (spICP-MS) as complementary analytical techniques. The results demonstrate that following their uptake via caveolae-mediated endocytosis, TiO2 NPs were trafficked through different intracellular compartments including early endosomes, multivesicular bodies, and late endosomes/endo-lysosomes, and eventually concentrated inside multilamellar vesicles. TEM and spICP-MS results provide evidence that uptake was nano-specific. Only NPs/NP agglomerates of a specific size range (~ 30-100 nm) were endocytosed; larger agglomerates were excluded from uptake and remained located in the extracellular space/exposure medium. NP number and mass inside cells increased linearly with time and was associated with an increase in particle diameter suggesting intracellular agglomeration/aggregation. No alterations in the expression of genes regulated by the redox balance-sensitive transcription factor Nrf-2 including superoxide dismutase, glutamyl cysteine ligase, glutathione synthetase, glutathione peroxidase, and glutathione S-transferase were observed. This shows that, despite the high intracellular NP burden (~ 3.9 × 102 ng Ti/mg protein after 24 h) and NP-interaction with mitochondria, cellular redox homeostasis was not significantly affected. This study contributes to a better mechanistic understanding of in vitro particokinetics as well as the potential fate and effects of TiO2 NPs in fish liver cells.