Article

Subtle alterations in swimming speed distributions of rainbow trout exposed to titanium dioxide nanoparticles are associated with gill rather than brain injury

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Abstract

The effects of engineered nanomaterials on fish behaviours are poorly understood. The present study aimed to determine the locomotor behaviours of trout during waterborne exposure to titanium dioxide nanoparticles (TiO(2) NPs) as well as inform on the underlying physiological mechanisms involved. Trout were exposed to either control (without TiO(2)), 1mgl(-1) TiO(2) NPs or 1mgl(-1) bulk TiO(2) for 14 days. Titanium dioxide exposure resulted in 31 (bulk) and 22 fold (nano) increases in the Ti concentrations of gill tissue compared to controls, but there were no measurable increases of Ti in the internal organs including the brain. Gill pathologies were observed in both TiO(2) treatments. Locomotor behaviours were quantified using video tracking software and the proportion of time spent swimming at high speed (>20cms(-1)) was significantly decreased in fish exposed to TiO(2) NPs, compared to controls, but not fish exposed to bulk TiO(2). The shift in swimming speed distribution in the TiO(2) NP-exposed fish was associated with decreased area of red pulp in the spleen, increases in haematocrit and whole blood haemoglobin, all consistent with a compensation for respiratory hypoxia without the accumulation of plasma lactate. Fish exposed to TiO(2) NPs also retained competitive abilities when paired with controls in aggressive social encounters. The duration of competitive contests, the level of aggression and contest outcome were not affected by NP exposure. Neurological injury did not explain the changes in locomotor behaviour, although there was some apparent enlargement of the blood vessels on the brain. Whole brain homogenates showed a statistically significant increase in oxidative stress defences such as the total glutathione pool, but without loss of Na(+)K(+)-ATPase or acetylcholinesterase activities.

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... In an ice bath, stock NP suspensions (10.0 g L −1 ) were sonicated (UP200S, Hielscher Ultrasonic Technology, Teltow, Germany) for 15 min with filtered artificial seawater at 100 W. The test concentrations (1 and 10 mg L −1 ) were achieved by diluting the stock. Concentrations within the range of 1-10 mg L −1 are commonly chosen as acute exposure concentrations in some aquatic animals (Federici et al., 2007;Chen et al., 2011;Boyle et al., 2013;Gornati et al., 2016). Nano-TiO 2 patterns were determined using X-ray diffraction analysis (XRD, X'Pert PRO X-ray Diffractometer, PANalytical B.V.). ...
... In environmental studies, an increase in size allows NPs to be captured and ingested by organisms that actively grab the particles from the water column during food search (Canesi et al., 2010), which affects the toxicity to organisms. In addition, the gills of fish are the primary organs in direct contact with the surrounding medium; thus, the internalization of nano-TiO 2 by fish may result in its accumulation in the gills leading to histopathological changes (Boyle et al., 2013;Chen et al., 2011;Federici et al., 2007;Xiong et al., 2011). ...
... However, at 30 psu, NKA activity was not affected by the exposure of up to 1 mg L −1 nano-TiO 2 . This result was in agreement with that of Boyle et al. (2013), who observed gill pathologies in 1 mg L −1 nano-TiO 2 treatments but without loss of NKA in juvenile rainbow trout. Chauhan et al. (2002) confirmed that NKA activity is negatively correlated with oxidative stress, and Wang et al. (2016) observed that NKA activities in gill, kidney, and intestinal tissues were significantly inhibited when the juvenile pufferfish T. obscurus was exposed to 5 mg L −1 Cd in seawater. ...
Article
Increased production of engineered nanoparticles has raised extensive concern about the potential toxic effects on marine organisms living in estuarine and coastal environments. Meanwhile, salinity is one of the key environmental factors that may influence the physiological activities in flatfish species inhabiting in those waters due to fluctuations caused by freshwater input or rainfall. In this study, we investigated the oxidative stress and histopathological alteration of the juvenile Paralichthys olivaceus exposed to nano-TiO2 (1 and 10 mg L-1) under salinities of 10 and 30 psu for 4 days. In the gills, Na+-K+-ATPase activity significantly deceased after 4 days 10 psu exposure without nano-TiO2 compared with 1 day of acclimating the salinity from the normal salinity (30 psu) to 10 psu. Under this coastal salinity, low concentration (1 mg L-1) of nano-TiO2 exerted significant impacts. In the liver, the activities of superoxide dismutase, catalase, the levels of lipid peroxide and malondialdehyde increased with nano-TiO2 exposed under 30 psu. Such increase indicated an oxidative stress response. The result of the integrated biomarker responses showed that P. olivaceus can be adversely affected by high salinity and high concentration of nano-TiO2 for a short-term (4 days) exposure. The histological analysis revealed the accompanying severe damages for the gill filaments. Principal component analysis further showed that the oxidative stress was associated with the nano-TiO2 effect at normal salinity. These findings indicated that nano-TiO2 and normal salinity exert synergistic effects on juvenile P. olivaceus, and low salinity plays a protective role in its physiological state upon short-term exposure to nano-TiO2. The mechanism of salinity mediating the toxic effects of NPs on estuarine fish should be further considered.
... mg L − 1 nTiO 2 of unspecified surface coating (Federici et al., 2007). Rainbow trout also showed kidney-and brain-localized oxidative stress when exposed to 1.0 mg L − 1 25 nm uncoated nTiO 2 , but not a bulk control (Boyle et al., 2013). In the latter study, both nanoscale and bulk forms induced gill histopathology, and the nanoscale form especially affected swimming behaviour (Boyle et al., 2013), ostensibly due to a hypoxic response and/or cerebral damage as evidenced by brain-specific markers of oxidative stress and abnormal vasculature. ...
... Rainbow trout also showed kidney-and brain-localized oxidative stress when exposed to 1.0 mg L − 1 25 nm uncoated nTiO 2 , but not a bulk control (Boyle et al., 2013). In the latter study, both nanoscale and bulk forms induced gill histopathology, and the nanoscale form especially affected swimming behaviour (Boyle et al., 2013), ostensibly due to a hypoxic response and/or cerebral damage as evidenced by brain-specific markers of oxidative stress and abnormal vasculature. Unlike a number of other ENM formulations, nTiO 2 on its own does not appear to be particularly harmful to crustaceans. ...
... Understanding the long term risks of ENMs to aquatic organisms will also require a better understanding of how sensitive histological and biochemical indicators of ENM toxicity translate into impacts on whole animal performance (Fig. 2). Acute exposures to high concentrations of certain ENMs can impact swimming behaviour (Boyle et al., 2013) or increase sensitivity to hypoxia (Bilberg et al., 2010) in a few species of freshwater fish but data for such environmentally-relevant endpoints is sparse. Damage to the gill epithelium is often observed following ENM exposures, so reductions in swimming performance and aerobic scope may be common, although rarely measured. ...
Article
Engineered nanomaterials (ENMs) are incorporated into numerous industrial, clinical, food, and consumer products and a significant body of evidence is now available on their toxicity to aquatic organisms. Environmental ENM concentrations are difficult to quantify, but production and release estimates suggest wastewater treatment plant effluent levels ranging from 10− 4 to > 10¹ μg L− 1 for the most common formulations by production volume. Bioavailability and ENM toxicity are heavily influenced by water quality parameters and the physicochemical properties and resulting colloidal behaviour of the particular ENM formulation. ENMs generally induce only mild acute toxicity to most adult fish and crustaceans under environmentally relevant exposure scenarios; however, sensitivity may be considerably higher for certain species and life stages. In adult animals, aquatic ENM exposure often irritates respiratory and digestive epithelia and causes oxidative stress, which can be associated with cardiovascular dysfunction and the activation of immune responses. Direct interactions between ENMs (or their dissolution products) and proteins can also lead to ionoregulatory stress and/or developmental toxicity. Chronic and developmental toxicity have been noted for several common ENMs (e.g. TiO2, Ag), however more data is necessary to accurately characterize long term ecological risks. The bioavailability of ENMs should be limited in saline waters but toxicity has been observed in marine animals, highlighting a need for more study on possible impacts in estuarine and coastal systems. Nano-enabled advancements in industrial processes like water treatment and remediation could provide significant net benefits to the environment and will likely temper the relatively modest impacts of incidental ENM release and exposure.
... These researchers observed changes in the haematopoietic tissue (spleen and head kidney) of rainbow trout under influence of stress. Recently, a study by Boyle et al. [20] showed that waterborne exposure to 1 mg l -1 of bulk or TiO 2 NPs materials for 14 days caused a decrease in the proportion of red pulp that a concomitant with an increase in the proportion of sinusoid space in the spleen of rainbow trout. Boyle et al. [20] also found an increase in the number of melanomacrophage deposits in the spleen with both bulk and TiO 2 NP treatments, with more elevation with NP treatment. ...
... Recently, a study by Boyle et al. [20] showed that waterborne exposure to 1 mg l -1 of bulk or TiO 2 NPs materials for 14 days caused a decrease in the proportion of red pulp that a concomitant with an increase in the proportion of sinusoid space in the spleen of rainbow trout. Boyle et al. [20] also found an increase in the number of melanomacrophage deposits in the spleen with both bulk and TiO 2 NP treatments, with more elevation with NP treatment. ...
... Physiological biomarkers were found to be beneficial in evaluating the current condition of fish exposed to metals or NPs. However, the ionic forms and NP forms of metals may exhibit different toxic effects (Griffitt et al., 2011;Boyle et al., 2013;Wang et al., 2014). A key mechanism of toxicity is the disruption of impulse signaling and osmoregulatory impairment associated with AChE and ATPase inhibitions in the associated organs. ...
... As occurred in the present study, AChE activity in the brain of fish decreased following titanium NP exposures. Boyle et al. (2013) also found that there were significant decreases in AChE activity in the brains of rainbow trout exposed to titanium NPs after 14 days of exposure. They also found significant decreases in the Uptake A C E Depurat on B D F Figure 6. ...
Article
Full-text available
The use of nanoparticles (NPs) has increased in recent years and consequently they are being released to the environment. The final destination of most NPs is the aquatic environments due to washing up by rain waters. Fish (120) were exposed to different concentrations (0, 1, 5, 25 mg/L) aluminium-oxide (Al2O3), copper-oxide (CuO) and titanium-dioxide (TiO2) NPs for 14 days and 14 days of depuration period (no NP in water). Following NP exposures, activities of Na,K-ATPase, Mg-ATPase, Ca-ATPase and acetylcholinesterase (AChE) in the brain or muscle were measured. AChE activity in the brain and muscle decreased significantly (P<0.05) following exposure to CuO NPs and TiO2 NPs, though Al2O3 NPs did not cause any significant (P>0.05) alteration. Similarly, Ca-ATPase activity in the muscle decreased significantly by Al2O3 NPs and CuO NPs, but not by TiO2 NPs. Total ATPase and Mg-ATPase activities did not alter significantly in the brain, though Na,K-ATPase activity decreased after exposure to CuO NPs. Half (60) of NP-exposed fish were transferred to NP-free waters for depuration experiments for 14 days. Transmission electron microscope images demonstrated NP aggregates in the tissues, though some NPs retained in the tissues after the depuration. This study showed that NPs are able to alter nervous system biomarkers, copper NP being the most effective one.
... Accordingly, the obtained results could be explained by each one of the main mechanisms (or their combination), which ultimately lead to toxicity of TiO 2 NPs on rainbow trout: (i) photocatalytic activity (phototoxicity) of TiO 2 NPs; (ii) physical stress associated with the size and surface properties of TiO 2 NPs (cytotoxicity); and/or (iii) capacity of TiO 2 NPs to adsorb other potential xenobiotics present in the exposure media (Callaghan and MacCormack, 2017;Clemente et al., 2015). Despite of these mechanisms, the occurrence of oxidative stress in rainbow trout could be most probably related to the direct production of ROS by TiO 2 NPs (with or without irradiation), which, ultimately, may be a result of the hypoxia induced by the adsorption of TiO 2 NPs to the gills, thereby causing the occlusion of this organ (Boyle et al., 2013). In brief, the interpretation of oxidative stress mechanisms caused by Ti present as TiO 2 NPs on fish are complex and should be interpreted with caution, since it depends of several factors like e.g. the exposure media, formulation type and experimental conditions. ...
... Although few studies have demonstrated that TiO 2 NPs caused respiratory distress associated with oxidative stress on fish (e.g. Boyle et al., 2013;Federici et al., 2007;Hao et al., 2009;Ramsden et al., 2009), none of them considered environmentally-relevant concentrations after long periods of time (chronic; 28 d) like those presented herein. ...
Article
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 (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.
... One of these technological advances is the implementation of video tracking technology and tracking software program in aquaculture research (Delcourt et al., 2013;Noldus et al., 2001). Some studies documented in the literature have focused on behavioral analysis of aquatic species (Boyle et al., 2013;Delcourt et al., 2013;Jijie et al., 2020;Simão et al., 2019;Stewart et al., 2015;Strungaru et al., 2019;Vera et al., 2010). However, few studies have examined the effects of anesthesia on fish swimming behavior. ...
... ). An increasing number of studies have used video tracking in aquatic species to get valuable information on toxicological agents, drugs and other study topics in recent years (Alyuruk et al., 2013;Bardera et al., 2020;Boyle et al., 2013;Hansen and Roslev, 2016;Jadot et al., 2005;Jijie et al., 2020). It is well established that anesthetic agents physiologically affect fish (Aydın and Akhan, 2020;Boaventura et al., 2020;de Freitas Souza et al., 2018;Hoseini et al., 2020;Taheri Mirghaed et al., 2018a), but only a few studies used video tracking to assess behavioral parameters of fish during the induction of anesthesia (Nordgreen et al., 2014;Readman et al., 2013Readman et al., , 2017. ...
Article
The present study examined the anesthetic efficiency and electrocardiographic and behavioral responses of the doctor fish Garra rufa anesthetized with thymol and carvacrol. Fish were subjected to anesthetic baths in five different concentrations of the thymol (25, 50, 75, 100, and 150 mg L − 1) and carvacrol (25, 50, 75, 100, and 150 μL L − 1). Induction and recovery times were recorded for each fish separately, and 10 fish were used per anesthetic concentration. Video tracking and processing were performed for each anesthetic to obtain changes in behavioral parameters between anesthetic concentrations. Thereafter, a different experiment was established for cardiographic evaluations, and necessary electrocardiographic (ECG) records were obtained in 5 fish. At the end of the experiments, all tested thymol and carvacrol concentrations effectively induced anesthesia in G. rufa. Video tracking analyses demonstrated that G. rufa did not exhibit any changes in behavioral parameters when submitted to 25-50 mg L − 1 concentrations of thymol compared to anesthetic-free water. However, movement distance and mobility significantly increased with increasing carvacrol concentrations. We found that high concentrations of thymol (150 mg L − 1) and carvacrol (100 and 150 μL L − 1) caused avoidance behaviors in G. rufa. ECG recordings showed that heart rate decreased, and PR and QT intervals were prolonged with increased thymol concentrations. Thymol concentrations did not affect PQ intervals. No significant changes in ECG parameters were observed with carvacrol. These results demonstrated that concentrations of 25 and 50 mg L − 1 thymol and 50 μL L − 1 carvacrol can be used for general aquaculture procedures, and 100 mg L − 1 thymol and 75 μL L − 1 carvacrol can be used as rapid anesthesia in G. rufa.
... The available studies focusing on the effects of BP-3 and TiO 2 NPs, despite reinforcing the relevancy of behavioural analysis in the toxicological context, do not demonstrated a clear pattern of responses. While BP-3 showed that the type and severity of the behavioural effects depend on the exposure via [24,45] and the tested concentrations, TiO 2 NPs were demonstrated to induce subtle alterations in fish swimming behaviour [46]. ...
... In the present study, no neurological disturbances of the cholinergic system were found in the brain after IP injection of TiO 2 NPs and BP-3, isolated or in mixture, for 3 and 7 days. In the same direction, several studies with freshwater fish reported no alterations in the AChE activity in the brain after waterborne exposure to TiO 2 NPs [46,[80][81][82][83]. On the contrary, waterborne exposure of the freshwater fish Carassius auratus to 200 µg L −1 of BP-3 promoted the increase in the activity of AChE [84]. ...
Article
Full-text available
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.
... Studies on other NMs have shown effects on animal behaviour, including for fish. These effects include altered swimming behaviour of rainbow trout after 14 days of exposure to 1 mg L −1 TiO 2 NPs (Boyle et al. 2013), decreased locomotion, exploration, shoaling, circadian rhythm, and social interaction in adult zebrafish exposure for 2 weeks to C 70 fullerene NPs (Sarasamma et al. 2019), and promoting (at low concentrations) and inhibiting (at high concentrations) zebrafish larval activity under exposure to graphene oxide particles (Chen et al. 2020). Further studies have reported that transition metal-doped TiO 2 NPs can cause alterations of behaviour in goldfish (Carassius auratus) and common carp (Cyprinus carpio; Pirsaheb et al. 2019) and both CuO NPs and TiO 2 NPs exposures induce behavioural changes including the enhanced rate of opercular activity, rapid swimming, convulsions, hyperactivity, loss of balance, and increased surfacing activity (Mansouri et al. 2016b). ...
... With increasing time of exposure, we found increased levels of hyperplasia and fusion of lamellar in the gills of the blackfish was intensified. The intensity of these responses might be expected to impair gaseous exchange (Boyle et al. 2013;Vigário and Sabóia-Morais 2014). The observations of aneurisms in blackfish' gills exposed to the MLGs have been also observed in adult zebrafish exposed to GO, and may, in turn, cause disturbances in blood flow in the gills (Handy and Maunder 2009). ...
Article
Full-text available
Zinc oxide nanoparticles (ZnO NPs) and multi-layer graphenes (MLGs) are widely used, and due to the lack of appropriate wastewater treatment may end up in the aquatic environment, with unknown consequences to biota. The main purpose of this study was to assess the acute toxicity, histopathological and behavioural changes caused by the exposure of ZnO NPs and MLGs, alone and combined, to the blackfish Capoeta fusca. The estimated mean 96 h-LC50 for ZnO NPs was 4.9 mg L⁻¹ and 68.4 mg L⁻¹ for MLGs. In combination, MLGs increased the acute toxicity of the ZnO NPs. The effects of the different NPs on the gills included hyperplasia, aneurisms, and fusion of the lamellae. In the intestine, exposure to the NPs resulted in an increase in the number and swelling of goblet cells and tissue degeneration. Loss of balance, restlessness, erratic and abnormal swimming patterns were the most common behavioural changes seen in the ZnO NPs’ exposed blackfish. In contrast with the acute toxicity findings, MLGs decreased the histopathological and behavioural effects of the ZnO NPs on both gills and intestinal tissues as well as fish behaviour. Our experimental results illustrated insights into the simultaneous exposure assessment of metal-based NPs and carbon nanomaterials, although further research is needed on the interactions exposure of these substances to interpreting the toxicological effects of metal-based nanomaterials seen in exposed organisms.
... In the brain of rainbow trout exposed to Cu NPs, metencephalon (cerebellum) regions showed increase in blood vessel diameter on the ventral surface of the cerebellum and occasional necrotic cells between the molecular and granular layer of cerebellum cortex (Genan et al. 2012). Exposure to TiO 2 NPs did not cause major change in gross anatomy of the brain except some necrotic cells in the cerebrum and some apparent enlargement of the blood vessels (Boylea et al. 2013). But the treatment decreased the brain metal Cu and Zn levels, and there was a trend of decreasing enzyme activity. ...
Chapter
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Nanoparticles (NPs) have been exploited in many consumer products, for example, silver nanoparticles (Ag NPs), due to their antibacterial properties, have been increasingly incorporated in a variety of products, including socks, home appliances, water treatment, medical equipment, and disinfection, etc. This chapter gives a review on the current studies in this area, which may help to make it clear for both the common and specific findings in view of nanotoxicological effects on fish. In view of aquatic nanotoxicity using fish model, the chapter discusses the effects including developmental toxicity, genotoxicity, and immunotoxicity, and shows various toxicities from different NPs. Organ pathologies from nanoparticles can be found in a range of organs including gill, liver, hematologic system, ocular and visual system, and brain. The chapter presents the bioavailability, bioaccumulation, and consequent toxicity of nanoparticles in fish vary considerably with fish species, toxicity assessing methods, nanoparticle formulation, and chemistry of exposure media.
... In fish, the observed altered locomotor behavior in response to NPs exposure may be due to induced neurotoxicity. Even though gill injury and consequent hypoxia have been suggested as the major reason for the decreased swimming speed in rainbow trout exposed to TiO 2 NP (Boyle et al., 2013), brain is also a major target organ of NP (Hu and Gao, 2010). ...
Article
Among pollutants, nanoparticles (NPs) consist a potential environmental hazard, as they could possibly harm the aquatic and terrestrial ecosystems while having unpredictable repercussions on human health. Since monitoring the impact of NPs on aquatic and terrestrial life is challenging, due to the differential sensitivities of organisms to a given nanomaterial, the present study examines magnetite nanoparticles' mediated toxicity in different animal models, representing distinctive environments (terrestrial and aquatic). Oxidative, proteolytic and genotoxic effects were evaluated on the hemocytes of the snail Cornu aspersum; in addition to those, apoptotic effects were measured in gills and liver of the zebrafish Danio rerio, and the prussian carp Carassius gibelio. All biochemical parameters studied increased significantly in animals after 8 days exposure to NPs. Inter-species and inter-tissues differences in responses were evident. Our results suggest a common toxicity response mechanism functioning in the tissues of the three animals studied that is triggered by magnetite NPs. The simultaneous use of these parameters could be established after further investigation as a reliable multi-parameter approach for biomonitoring of terrestrial and aquatic ecosystems against magnetite nanoparticles. Additionally, the results of our study could contribute to the design of studies for the production and rational utilization of nanoparticles.
... Some NPs contain extremely toxic metals such as silver and some contain metals known for lower toxicities such as iron. Nevertheless, ionic form and NP form of a metal may exhibit different toxic effects [4][5][6], therefore nanotoxicology has emerged as new area for toxicology. Because many products that human use contain NPs such as suntan cream, toothpaste, medicals, textile, electronic, toys, moisturizer and some are used in food, nanotoxicology studies should be carried out in different classes of animals in the aquatic environments and also in terrestrial animals [7][8][9][10]. ...
Article
Full-text available
The use of nanoparticles (NPs) in diverse field of nanotechnology has been increased in the last decades and especially the aquatic environments have been contaminated by waste products. Because the potential toxic effects of NPs have been documented in different groups of animals, the present study was carried out to help understanding the toxic effects of three NPs in freshwater fish. In this work, Oreochromis niloticus were exposed to aluminum oxide (Al2O3), copper oxide (CuO) and titanium dioxide (TiO2) NPs in differing concentrations (0, 1, 5, 25 mg/L) for 14 d. Following the exposures, the activities of total ATPase, Mg-ATPase and Na,K-ATPase in the osmoregulatory organs (gill, kidney) of fish were measured. Additionally, the aggregates of NPs in the gill and intestine of fish which are the possible entrance to the blood stream were demonstrated by a transmission electron microscope (TEM) to demonstrate the histopathological effects of NPs. Thus, the aim of this study was to evaluate the relationship between the histological view of tissues and changes in ATPase activity. Data showed that all NPs decreased significantly (P<0.05) ATPase activities in most cases. In general, Al-NPs and Cu-NPs decreased significantly (P<0.05) all ATPase activities in the gill and kidney at the highest and medium exposure concentrations. Similarly, Ti-NPs also decreased significantly all ATPase activities in the kidney at the highest and medium exposure concentration, though none of Ti-NP concentrations caused significant change (P>0.05) in ATPase activity in the gill. Overall, data demonstrated that the least affected enzyme was Mg-ATPase and the least toxic NP was Ti-NP. TEM images demonstrated that all NPs accumulated in the tissues of fish in 14 days of exposure period, but not eliminated completely after 14 days of depuration period. There were considerable changes in histological images between control fish tissues and NP exposed fish tissues. NP aggregates in the intercellular space and in the cells can be seen from the TEM images, indicating the decreases in ATPase activities occurred due to histopathological changes. This study demonstrated that NPs are able to cause changes in tissue structures and ATPases were very sensitive to NP exposures. Data suggested that there should be more studies to understand better the toxic effects of NPs in fish.
... Rainbow trout, Oncorhynchus mykiss, is one of most popular fish species around the world, due to its excellent meat quality (Vehviläinen et al. 2008). It is also one of the most studied species and is widely used for research in many fields such as carcinogenesis, toxicology, immunology, ecology, physiology, and nutrition (Thorgaard et al. 2002;Cowey 1992;Boyle et al. 2013;Berthelot et al. 2014). Global rainbow trout production from aquaculture has grown tremendously and has reached 814,090 metric tons as of 2016 (FAO 2018). ...
Article
Five experimental diets were formulated to evaluate the effects of dietary enzymatically hydrolyzed tuna by-product on growth, non-specific immune responses, and hematology of juvenile rainbow trout (Oncorhynchus mykiss). A basal diet with 50% of fishmeal was used as control (CON) and four other diets replaced 12.5% (TBB12.5), 25% (TBB25), 37.5% (TBB37.5), and 50% (TBB50) of fish meal in the CON diet. Juvenile rainbow trout (4.87 ± 0.05 g) were randomly distributed into 15 tanks (50 L) and fed 3–4% of wet body weight two times a day. At the end of 7 weeks of feeding trial, weight gain, specific growth rate, feed efficiency, and protein efficiency ratio of fish fed CON diet were significantly higher than those of fish fed TB50 diet (P < 0.05). But there were no significant differences among fish fed CON, TBB12.5, TBB25, and TBB37.5 diets (P > 0.05). There were no significant differences in GPT levels among fish fed CON, TBB12.5, TBB25, and TBB37.5 diets. Also, there were no significant differences in lysozyme, superoxide dismutase, glucose, and total protein levels in all experimental diet (P > 0.05). The broken-line analysis indicated that the minimum dietary level of enzymatically hydrolyzed tuna by-product to replace fishmeal could be 29.7% in rainbow trout. These results indicated that the optimum level of dietary enzymatically hydrolyzed tuna by-product could replace greater than 29.7% but less than 37.5% of fishmeal in juvenile rainbow trout diet.
... Ajani et al. (2007) reported decreased lymphocytes levels observed in water borne toxicants exposed African cat fish (Clarias gariepinus). Decreased leucocyte count rainbow trout and zebra fish blood exposed to 1 mg l −1 and 0.1-1 mg l −1 of TiO 2 NPs for 14 days respectively (Boyle et al., 2013;Ramsden et al., 2013). Similarly, our results showed decreased lymphocytes and increased WBC, monocytes levels in nanoparticles treated groups. ...
Article
The present study was aimed to analyze the effect of ZnO and TiO2 nanoparticles (NPs) on Haemato-immunological parameters in adult Tilapia, Oreochromis mossambicus. The nanoparticles size found as 47 nm and 30 nm for ZnO and TiO2 respectively. The acute toxicity (96 h) of ZnO (LC50: 100–110 ppm) and TiO2 (LC50: 80–90 ppm) NPs were identified by using probit analysis. RBC, Hb and HCT levels decreased in nanoparticles exposed groups resulted in decreased oxygen carrying capacity of RBC and other erythrocyte indices (MCH, MCV, MCHC). Increased WBC, neutrophils & monocytes and decreased lymphocyte levels were observed as increased concentration of the nanoparticles. The results were found as statistically significant (p < 0.05). In conclusion, the present study depicts that ZnO NPs exhibits more toxicity than TiO2 NPs. Nanoparticles presence even in low concentration (ppm) cause damage to the connective tissues of fish, so the existing permissible levels of these nanoparticles in water are need to be revised.
... Sublethal effects on aquatic biota encompassing reduced motility and swimming (Boyle et al. 2013), reduced growth and reproduction (Zhao and Wang 2011), bioaccumulation (Rosenkranz et al. 2009), digestive stress and reduced feeding (Croteau et al. 2011) have been observed in freshwater species like Daphnia magna (waterflea), Lymnaea stagnalis (pond snail) and Caenorhabditis elegans (nematode) for nanoparticle interactions. Most deleterious effects by nanoparticles occur at the microscopic planktonic stage of development of marine organisms. ...
Article
Human activities such as industrialisation, urbanisation and agriculture have adversely impacted terrestrial and aquatic ecosystems. Water pollutants such as heavy metals and nanoparticles can undergo bioaccumulation and bioaugmentation. Heavy metals cannot be degraded and are hence added permanently. Nanoparticles are a potential threat because of their small size and unique properties. This article reviews the impact of various pollutants on aquatic biota and presents remediation methods. Benthic macroinvertebrates can be used as bioindicators to study the impact of pollutants on aquatic ecosystems. Fishes occupy the highest trophic level in the aquatic food chain and can therefore accumulate large amounts of metal from water, ultimately leading to biomagnification. Some organic compounds such as pesticides and fungicides are carcinogenic and sometimes resistant to degradation.
... Likewise, Zebra fish embryos exposed to silver nanoparticles for 120hpf showed significantly suppressed locomotion and a clear shift toward inactivity (Asmonaite et al. 2016). Contrary to above two studies, in a study done by Boyle et al. (2013) unchanged locomotory behavior was observed in rainbow trout after exposure of titanium dioxide nanoparticles. Adult zebra fish showed disturbance in light/dark preference and damping exploratory behavior after exposure of silicon nanoparticles (Li et al. 2020). ...
Article
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In recent years, the production and utilization of nanomaterials have increased many folds due to massive advancement in industrialization and urbanization as well as their increasing application in various sectors. Nanoparticles from these nanomaterials may release into the aquatic environment during their different stages of life cycles and may cause deleterious effects on aquatic fauna. The impact of the nanoparticles on the aquatic organisms is still largely unknown and less addressed. Although many studies have been performed to demonstrate toxicity caused by various types of nanoparticles to aquatic organisms, there is still less information related to suitable biomarkers or biological parameters used. Therefore, the aim of this review article is to carry out an assessment of available peer reviewed research reports in which different biological parameters were used to study effect of different nanoparticles on the aquatic organisms, especially fishes. Firstly, in this review the various sources of nanoparticles into the aquatic environment, different uptake routes of nanoparticles into the fish body, and their mechanism of action were discussed. After that, major emphasis as well as less emphasis given biological parameters or biomarkers to study nanoparticles toxicity to fishes by different researchers have been categorized and suitably illustrated. Furthermore, some new biomarkers or biological parameters which can be used to demonstrate nanoparticles toxicity were also discussed. In conclusion, this review will help the researchers to find out new biomarkers to study nanoparticles toxicity so that various biological mechanisms can be explored to assess the adverse effects of nanoparticles.
... Effects on behaviour can occur at much lower exposure concentrations than expected for traditional toxicological endpoints (Melvin and Wilson, 2013). Therefore, due to their rapidity and sensitivity, behavioural analyses are often used to establish effects from contamination in comparison with the standard LC50 approach which is often used in ecotoxicology and may be ideal for studying the effects of different pollutants (Scott and Sloman, 2004;Boyle et al., 2013). Among aquatic organisms, fish are widely used to investigate the effects of different pollutants on behavioural responses and are considered a great model for this purpose (Scott and Sloman, 2004). ...
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Microplastics and mercury are environmental pollutants of great concern. The main goal of the present study was to investigate the effects of these pollutants, both individually and in binary mixtures, on the swimming performance of juvenile European seabass, Dicentrarchus labrax. Microplastics alone, mercury alone and all the mixtures caused significant reduction of the swimming velocity and resistance time of fish. Moreover, changes in behavioural responses including lethargic and erratic swimming behaviour were observed. These results highlight that fish behavioural responses can be used as sensitive endpoint to establish the effects of contamination by microplastics and also emphasizes the need to assess the combined effects of microplastics and other environmental contaminants, with special attention to the effects on behavioural responses in fish and other aquatic species.
... In this respect, Saucier and Astic (1995) did not observe any metal concentration in the OT despite hyperplasia and hypertrophy of some goblet cells. Moreover, Boyle et al. (2013) studied the exposure of fish to nanoparticles of titanium dioxide at 1 mg L À1 over a period of 14 days and did not observe any contaminant concentration in the brain, but highlighted a secondary toxicity associated to hypoxia. ...
Article
Marine environments are affected by large amounts of toxicants among those mercury (Hg). The aim of this study was to assess potential neurotoxic effects of Hg in the peacock blenny Salaria pavo. A sublethal contamination to 66 μg HgCl2 L-1 over periods of 1, 4, 10 and 15 days was performed. Total Hg concentrations measured in the brain highlighted the detection of Hg at days 1 and 4 following the exposure but no concentration of the metal was further detected. Partial-length cDNA of genes coding ABC transporters (abcb1, abcc1, abcc2, abcg2) and acetylcholinesterase (ache) were characterized. Results from mRNA expression levels displayed an up-regulation of abcb1 mRNA while a down-regulation of abcc1 and abcc2 mRNA was observed. No change in abcg2 and ache mRNA expression was noted throughout the experiment. At each sampling time, Hg exposure did not affect the activity of the AChE enzyme. The histological analysis indicated that fish exhibited several damages in the optic tectum and the cerebellum and 3 reaction patterns were identified for each organ: circulatory disturbances, regressive and progressive changes. Molecular, physiological and histological biomarkers assessed in the present study highlighted that peacock blennies were able to detoxify Hg from the brain tissue by developing defense mechanisms. More globally, neurotoxic effects of a sublethal Hg exposure in the brain of peacock blennies and the adaptation capacity of this species were evaluated.
... Investigation of clearing mechanisms in zebrafish embryos is limited due to short assay time span of 120 h. However, in adult zebrafish most particles are excreted from the body via the liver, spleen and gall bladder (Boyle et al., 2013;Jung et al., 2014;Kashiwada, 2006;Zhao et al., 2011). Excretion from cells and subsequently from tissues occurs at a much slower rate than uptake, which can occur within half an hour (particles found intracellularly; Fang et al., 2011). ...
Article
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In ecotoxicology, it is continuously questioned whether (nano)particle exposure results in particle uptake and subsequent biodistribution or if particles adsorb to the epithelial layer only. To contribute to answering this question, we investigated different uptake routes in zebrafish embryos and how they affect particle uptake into organs and within whole organisms. This is addressed by exposing three different life stages of the zebrafish embryo in order to cover the following exposure routes: via chorion and dermal exposure; dermal exposure; oral and dermal exposure. How different nanoparticle sizes affect uptake routes was assessed by using polystyrene particles of 25, 50, 250 and 700nm.
... Bekheet et al. (2010) reported vacuolization in the molecular layer after the exposure of rats to morphine. However, dilatation of blood vessels in the ventral surface of the cerebellum may represent a pathological sign; it is a part of the extended vasodilator response in order to ensure oxygen supply to compensate damages (Boyle et al., 2013). ...
Article
Cadmium (Cd) is considered as an important factor involved in several neurological disturbances. The aim of this study was to assess the effects of Cd in the brain of peacock blennies Salaria pavo, a species used as a bioindicator of water pollution. A sublethal contamination of 2 mg CdCl2 L⁻¹ was performed over periods of 1, 4, 10 and 15 days. Total Cd accumulation was measured in brains and displayed low concentrations throughout the experiment. Partial-length cDNA of different ATP-binding cassette transporters (abcb1, abcc1, abcc2, abcg2 proteins) and acetylcholinesterase (ache) were characterized. mRNA expressions profiles displayed an up-regulation of abcc2 mRNA after 4 days of Cd exposure only while abcg2 mRNA was down-regulated after 10 days only. For AChE, the mRNA transcription and the activity of the enzyme were followed and highlighted that Cd exerted an inhibitory effect on the nervous information transmission. At the histological level, fish exhibited pathological symptoms in the optic tectum and the cerebellum and results showed that the cerebellum was the most affected organ.
... However, many researches have been observing the swimming behavior against different pollutants, as Yu et al. [25] who observed in Takifugu rubripes that crude oil and dispersed crude oil significantly affected the critical swimming speed and, Boyle et al. [26], who reported that the proportion of time swimming at high speed was significantly reduced in Oncorhynchus mykiss exposed to titanium dioxide nanoparticles, compared to the control. ...
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Use of Swimming Capacity to Evaluate the Effect of Mercury on Poecilia vivipara (Poecilideos)According to Salinity and Temperature This study aimed to investigate the effects of the exposed to mercury, under the influence of different temperatures and salinities, on the swimming capacity of Poecilia vivipara. For this purpose, swimming capacity was estimated through exposure in aqueous medium, in twelve possible combinations, with different concentrations of mercury (0.0 μg/L, 10 μg/L, 20 μg/L and 30 μg/L), three salinities (35, 20 and 5) and three temperatures (25oC, 20oC and 15oC). The results show that the swimming capacity decreased according to the mercury concentration in all temperatures and salinities studied. At the highest tested concentration of mercury at 25°C, there was a decrease on swimming capacity of 84.4%, 91.2% and 97.1% in the salinities 35, 20 and 5, respectively. Generally speaking, averages were significantly different compared to control at the highest concentration of the mercury and in all temperatures. At lower salinity employed there was a corresponding increase in mercury toxicity and a decrease in swimming capacity. Swimming activity is a valid parameter and consistent index of the sublethal toxic effect that can be easily incorporated into the assay protocols to work with standard toxicity tests.
... Low acute toxicity with half-lethal concentration (LC 50 ) > 100 mg/mL has been described for zebrafish (Xiong et al., 2011) and rainbow trout (Oncorhynchus mykiss) (Federici et al., 2007). However, prolonged exposure of fish to TiO 2 -NPs induced biochemical and histopathological alterations in their gills, liver and intestines (Blaise et al., 2008;Boyle et al., 2013;Federici et al., 2007). ...
Article
Titanium dioxide nanoparticles (TiO2-NPs) have a wide number of applications in cosmetic, solar and paint industries due to their photocatalyst and ultraviolet blocking properties. The continuous increase in the production of TiO2-NPs enhances the risk for this manufactured nanomaterial to enter water bodies through treated effluents or agricultural amendments. TiO2-NPs have shown very low toxicity in a number of aquatic organisms. However, there are no conclusive data about their deleterious effects and on their possible mechanisms of toxic action. At this level, in vitro cell culture systems are a useful tool to gain insight about processes underlying the toxicity of a wide variety of substances, including nanomaterials. Differences in the physiology of different taxa make advisable the use of cells coming from the taxon of interest, but collecting data from a variety of cellular types allows a better understanding of the studied processes. Taking all this into account, the aim of the present study was to assess the toxicity of three types of TiO2-NP, rutile hydrophobic (NM-103), rutile hydrophilic (NM-104) and rutile-anatase (NM-105), obtained from the EU Joint Research Centre (JRC) repository, using various fish cell lines (RTG-2, PLHC-1, RTH-149, RTL-W1) and rainbow trout primary hepatocytes. For comparative purposes, the effect of different dispersion protocols, end-point assays and extended exposure time was studied in a fish cell line (RTG-2) and in the rat hepatoma cell line (H4IIE). TiO2-NPs dispersions showed a variable degree of aggregation in cell culture media. Disruption of mitochondrial metabolic activity, plasma membrane integrity and lysosome function was not detected in any cell line after exposure to TiO2-NPs at any time and concentration ranges tested. These results are indicative of a low toxicity of the TiO2-NPs tested and show the usefulness of fish cells maintained in vitro as high throughput screening methods that can facilitate further testing in the framework of integrated testing strategies.
... TBARS assay using fish tissues was performed following a previous study with minor modification. 29 Briefly, the supernatant of the homogenized samples were treated with thiobarbituric acid and TBARS formation was quantified by fluorescence measurement at 531 and 572 nm (excitation and emission, respectively). In addition, the intrinsic oxidative potentials of HF-FPW fractions alone were also determined via a modified protocol from Biaglow et al. (1997). ...
Article
The effects of hydraulic fracturing (HF) flowback and produced water (HF-FPW), a complex saline mixture of injected HF fluids and deep formation water that return to the surface, was examined in rainbow trout (Oncorhynchus mykiss). Exposure to HF-FPWs resulted in significant induction of ethoxyresorufin-O-deethylase (EROD) activity in both liver and gill tissues. Increased lipid peroxidation via oxidative stress was also detected by Thiobarbituric acid reactive substances (TBARS) assay. The mRNA expressions of a battery of genes related to biotransformation, oxidative stress, and endocrine disruption were also measured using quantitative real-time polymerase chain reaction (Q-RT-PCR). The increased expression of cyp1a (2.49±0.28-fold), udpgt (2.01±0.31-fold), sod (1.67±0.09-fold) and gpx (1.58±0.10-fold) in raw sample exposure group (7.5%) indicated elevated metabolic enzyme activity, likely through aryl-hydrocarbon receptor pathway, and generation of reactive oxygen species. In addition, the elevated vtg and era2 expression demonstrated endocrine disrupting potential exerted by HF-FPW in rainbow trout. The overall results suggested HF-FPW could cause significant adverse effects on fish, and the organic contents might play the major role in its toxicity. Future studies are needed to help fully determine the toxic mechanism(s) of HF-FPW on freshwater fish, and aid in establishing monitoring, treatment, and remediation protocols for HF-FPW.
... Locomotor behavior of zebrafish is influenced by many factors, including neurotoxicity, neuromuscular or physiological injury. Gill injury and subsequent hypoxia have been suggested as the major reason for the decreased swimming speed in rainbow trout exposed to titanium dioxide NPs 42 . In all our experiments, only zebrafish scored as "normal" in the semi-quantitative scale were included in the PMR/LMR assay. ...
Article
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Nanomaterials are being extensively produced and applied in society. Human and environmental exposures are, therefore, inevitable and so increased attention is being given to nanotoxicity. While silica nanoparticles (NP) are one of the top five nanomaterials found in consumer and biomedical products, their toxicity profile is poorly characterized. In this study, we investigated the toxicity of silica nanoparticles with diameters 20, 50 and 80 nm using an in vivo zebrafish platform that analyzes multiple endpoints related to developmental, cardio-, hepato-, and neurotoxicity. Results show that except for an acceleration in hatching time and alterations in the behavior of zebrafish embryos/larvae, silica NPs did not elicit any developmental defects, nor any cardio- and hepatotoxicity. The behavioral alterations were consistent for both embryonic photomotor and larval locomotor response and were dependent on the concentration and the size of silica NPs. As embryos and larvae exhibited a normal touch response and early hatching did not affect larval locomotor response, the behavior changes observed are most likely the consequence of modified neuroactivity. Overall, our results suggest that silica NPs do not cause any developmental, cardio- or hepatotoxicity, but they pose a potential risk for the neurobehavioral system.
... In turn, de Oliveira et al. observed inhibition of AChE activity and a reduction in the exploratory performance in adult zebrafish exposed to SPION coated with cross-linked aminated dextran [141]. On contrary, Boyle et al. reported no accumulation of NPs neither decrease in the activity of Na + /K + -ATPase and AChE in brain of trout exposed to TiO 2 NPs for 14 days, despite a significant increase in the total glutathione pool [142]. Similarly, in a study conducted by Ramsden et al., after 14 days of aqueous exposure of zebrafish to TiO 2 NPs, no changes were observed in Na + /K + -ATPase activity in the brain [143]. ...
Article
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Metallic nanoparticles due to their small size and unique physico-chemical characteristics have found excellent applications in various branches of industry and medicine. Therefore, for many years a growing interest has been observed among the scientific community in the improvement of our understanding of the impact of nanoparticles on the living organisms, especially on humans. Considering the delicate structure of the central nervous systemit is one of the organs most vulnerable to the adverse effects of metallic nanoparticles. For that reason, it is important to identify the modes of exposure and understand the mechanisms of the effect of nanoparticles on neuronal tissue. In this review, an attempt is undertaken to present current knowledge about metallic nanoparticles neurotoxicity based on the selected scientific publications. The route of entry of nanoparticles is described, as well as their distribution, penetration through the cell membrane and the blood-brain barrier. In addition, a study on the neurotoxicity in vitro and in vivo is presented, as well as some of the mechanisms that may be responsible for the negative effects of metallic nanoparticles on the central nervous system. Graphical abstract: This review summarizes the current knowledge on the toxicity of metallic NPs in the brain and central nervous system of the higher vertebrates.
... Xiong et al. (2011) also observed that ROS in zebra fish exposed to 50 mg/l TiO 2 NP, was elevated by 139.7% to 178.1% relative to the control group due to their protein carbonyl content. Similar changes were observed in zebrafish ( Bar-Ilan et al., 2013) and rainbow trout (Boyle et al., 2013). In contrast, Federi- ci et al. (2007) observed that rainbow trout subjected to high level of TiO 2 NP (0.1-1 mg/l) for 14 days naturally still had the ability to scavenge the ROS. ...
... Xiong et al. (2011) also observed that ROS in zebra fish exposed to 50 mg/l TiO 2 NP, was elevated by 139.7% to 178.1% relative to the control group due to their protein carbonyl content. Similar changes were observed in zebrafish (Bar-Ilan et al., 2013) and rainbow trout (Boyle et al., 2013). In contrast, Federici et al. (2007) observed that rainbow trout subjected to high level of TiO 2 NP (0.1-1 mg/l) for 14 days naturally still had the ability to scavenge the ROS. ...
Article
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Nanoproducts became widely used materials all over the world. Antimicrobial properties of titanium dioxide (TiO2) nanoparticle (NP) were examined against Aeromonas hydrophila (A. hydrophila) bacteria and the minimum inhibitory concentration (MIC) was found to be 20 μg/ml of TiO2NP. In addition, the treatment efficacy of TiO2NP was examined in Oreochromis niloticus (O. niloticus) infected with A. hydrophila. One hundred and eighty fish (54±2.4 g b.w.) were divided into six groups (G). O. niloticus in G1, G2 and G3 were fed for 30 days with 0, 20 and 100 μg/g b.w. TiO2NP, respectively, while G4, G5 and G6 were i.p. injected with 0.2 ml distal water, 20 and 100 μg/g b.w. TiO2NP, respectively, for three times with ten days of interval. The blood parameters as well as some of the biochemical parameters of O. niloticus that received high dosage of TiO2NP were significantly affected regardless to the administration route. Elevation of the activities of glutathione peroxidase (GPx) and metallothionine (MT) were recorded with the high dosage. Furthermore, O. niloticus subjected to high dosage of TiO2NP had the lower survival rate (SR%) especially with the injection route (50%). On the other hand, no significant changes were demonstrated with the perceived TiO2NP MIC. The mortality rate (MR%) of challenged O. niloticus against A. hydrophila was decreased in case of TiO2NP MIC exposure, as G2 and G5 revealed 20 and 30%, respectively. Therefore, the 20 μg/g b.w. of TiO2NP could safely protect O. niloticus against A. hydrophila infection since no health hazards was observed. Meanwhile, health status of O. niloticus was adversely affected with high dosage of TiO2NP irrespective to the route of administration.
... TiO 2 NPs reduced sperm motility in Rainbow trout sperm cells ( Ozgur et al., 2018 ). According to a report in 2013, gill damage instead of brain damage is responsible for slow locomotion observed in Zebrafish exposed to TiO 2 NPs ( Boyle et al., 2013 ). TiO 2 NPs caused liver damage and oxidative stress in two freshwater fishes Carassius auratus and Danio rerio ( Diniz et al., 2013 ). ...
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The use of chemicals, surfactants, and polymers in improving the property of drilling fluid and enhancing the effectiveness of drilling process and in tertiary oil recovery is costly and ineffective in handling the challenges. Metal and metal oxide nanoparticles (MMO NPs) have gotten attention in recent time on their use in oil drilling processes. Lately, there are several articles suggesting the benefits, properties, and effectiveness of the use of MMO NPs in drilling mud. They propose and recommend the incorporation of MMO NPs in drilling fluids. MMO NPs of iron, copper, zinc, cerium, aluminium, nickel, zirconium, tin, magnesium, titanium, and silicon are used in oil drilling processes due to their benefits in achieving effective drilling. They perform better than conventional compounds in eliminating and mitigating the challenges caused by water-based mud. However, there is a concern of the eco-friendly property and aquatic toxicity, via improper disposals and runoffs. This review focuses on the aquatic toxicological concerns of these in-use and recommended for use MMO NPs on teleost fish which is a major aquatic organism with huge public health implications in humans. The findings from this review using experimental data prove the potentiality and possible aquatic toxicity of MMO NPs. Therefore, we recommend that their use should be monitored and strictly regulated until there is a standard monitoring technique and a detailed understanding of their effect, fate, and behaviour in aquatic environment.
... 15 These tissue concentrations are consistent with predicted oral intake levels of 0.06-5.5 mg TiO 2 per kg body weight per day, previously reported in studies examining TiO 2 content in typical human diets. [15][16][17][18] NP internalization has also been reported for uptake routes such as diet, [15][16][17][18][19][20][21][22] inhalation, 23,24 dermal contact 5,25 and across the gills of fish, [26][27][28][29][30][31] and related reports have also shown that the spleen, kidney and liver are major organ depots for circulating NPs. 27,28,30,[32][33][34][35][36] Extensive research has been conducted on the effects of NPs on blood, [37][38][39][40][41][42] blood cells, [43][44][45][46][47] and the cardiovascular system. ...
Article
Nanoparticles (NP) that penetrate external protective barriers of an animal are most likely transported and distributed to various tissues and organs via the circulatory system. Whilst much attention has been dedicated to NP effects on target organs, surprisingly few studies have investigated effects on the vascular system itself, despite the critical role it plays in transporting red and white blood cells, nutrients, as well as coordinating many physiological responses, like immunity and stress. In this study we perfused iliac arteries extracted from cane toads (Rhinella marina) with polyacrylic acid (PAA) coated TiO2 NPs (3-9 nm) to directly assess effects on uptake across luminal endothelial layers, changes to vessel physiological function and toxicity. Perfusion of the iliac artery with 400 µg/mL PAA-TiO2 NPs resulted in histopathological changes in the vascular endothelial layer due to increased endothelial cell death via apoptosis. The PAA-NPs were observed to penetrate at least two cell layers and were present in both endothelial cells and underlying smooth muscle cells. Dual-wire myography experiments revealed that the highest dose of PAA-TiO2 NPs significantly inhibited the ACh-mediated vasodilation in blood vessels by ~50%, which appeared to be attributable to the damaged endothelial layer in the lumen of the vessels. This is the first study to use an ex vivo perfusion method that mimics the blood circulation coupled with dual-wire myography to demonstrate the adverse effects of NPs on blood vessel physiology.
... Determination of lipid peroxidation using thiobarbituric acid reactive substances assay Determination of thiobarbituric acid reactive substances (TBARS) assay was used to determine lipid peroxidation as per the original protocol described by Camejo et al. (29) with slight modifications as used in our laboratory conditions (30). Briefly, liver samples (from individual fish) were weighed and homogenised (1:10, wet tissue weight/buffer volume) using a Potter-Elvehjem glass homogeniser in a buffer of 20 mM Tris-HCl (pH 7.6), containing 1 mM dipotassium EDTA, 0.15 M potassium chloride, 0.5 M sucrose and 1 mM dithiotheritol. ...
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In fish, a complex set of mechanisms deal with environmental stresses including hypoxia. In order to probe the hypothesis that hypoxia-induced stress could be manifested in varieties of pathways, a model species, mirror carp (Cyprinus carpio), were chronically exposed to hypoxic condition (dissolved oxygen level: 1.80 ± 0.6 mg/l) for 21 days and subsequently allowed to recover under normoxic condition (dissolved oxygen level: 8.2 ± 0.5 mg/l) for 7 days. At the end of these exposure periods, an integrated approach was applied to evaluate several endpoints at different levels of biological organisation. These included determination of (i) oxidative damage to DNA in erythrocytes (using modified comet assay), (ii) lipid peroxidation in liver samples by measuring the malondialdehyde production using the 2-thiobarbituric acid [i.e. thiobarbituric acid reactive substances (TBARS) assay] and (iii) histopathological changes in gills. In addition, transcriptional expression of hypoxia-inducible factor 1 α (HIF-1α) and genes involved in the repair of oxidative damage to DNA (i.e. ogg1) and base excision repair (i.e. xrcc1) using reverse transcription polymerase chain reaction in liver samples were also determined. The results suggested significantly enhanced expression of these genes in response to hypoxia compared to concurrent normoxic controls. While the expression of HIF-1α reverted to control values within 7 days exposure to normoxic condition (P < 0.05), the transcriptional expression of the two genes involved in DNA repair process remained significantly high under the recovery period, which complemented the induction of oxidative damage to DNA. Hypoxic groups showed significantly increased values for TBARS level (~2-fold) and histopathological changes in gill tissues compared to both normoxic and recovery groups. Overall, oxidative damage to DNA determined by modified comet assay reflected the observed biological responses in other tissues of the fish. Along with other parameters, this integrated experimental design further strengthens the applications of the comet assay as an important technique to assess stress-induced DNA damage in ecotoxicological studies.
... According to literature, prolonged exposure of fish to TiO 2 -NPs have induced biochemical and histopathological alterations in gills, liver and intestines (Blaise et al., 2008;Linhua et al., 2009;Boyle et al., 2013). In the present study, the elevation of GOT and GPT activities in liver and muscle may be due to accumulation of TiO 2 NRs in these organs/ tissue which leads to tissue damage. ...
Article
Titanium dioxide (TiO2) nanoparticles are extensively manufactured due to their potential properties and applications invarious fields such as biomedical, electrical and environmental. These particles are likely to reach the aquatic environmentand may cause adverse effects on aquatic organisms. In this study, we investigated the effects of different concentrations (1, 50 and 100 mg L-l) of TiO2 nanorods (NRs). The enzymatic activity of glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), and lactate dehydrogenase (LDH) was measured in the liver and muscle of an Indian major carp, Cirrhinus mrigala, under short-term exposure (96 h). The synthesised particles were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), UV-Visspectroscopy (UV-Vis) and photoluminescence (PL) techniques before conducting the toxicity assay. The GOT and GPT activities were significantly elevated in both liver and muscle of fish treated with TiO2 nanorods (except 50 mg L-l in muscle for GPT). Similarly, the activity of LDH was also found to be elevated. The findings of the present investigation suggest that TiO2:NRs might have be absorbed, circulated, accumulated in liver and muscles of C. mrigala resulting in alterations in the enzyme activities. The results revealed that TiO2 nanorods induced alterations in GOT, GPT and LDH activities of fish at tested concentrations. The alterations of these enzymatic parameters can be useful for monitoring the environmental contamination of titanium dioxide (TiO2) nanoparticles in freshwater ecosystem.
... On the other side, TiO 2 NP is known for its relative low toxicity. Rainbow trout exposed to 1.0 mg/L TiO 2 NP for 96 h (Boyle et al., 2013) or one time intravenously administered with 100 µg TiO 2 NP for 14 days (Scown et al., 2009) both displayed very few effects on spleen, kidney, or other tissue functions. In zebrafish, TiO 2 NP exposure at 0.1-1 mg/L for 120 h did not have adverse effect on embryonic development, but significantly decreased larval swim velocity (Chen et al., 2011b). ...
Article
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Both tetrabromobisphenol A (TBBPA) and titanium dioxide nanoparticle (TiO2 NP) have widespread commercial applications, resulting in their ubiquitous co-presence in the environment and biota. Although environmental chemicals exist as mixtures, toxicity studies are nearly always conducted with single chemicals. Few studies explore potential interactions of different chemical mixtures. In this study, we employ the sensitive developing nerve system in zebrafish to assess the neurotoxicity of TBBPA/TiO2 NP mixtures. Specifically, zebrafish embryos were exposed to solvent control (0.1% DMSO), 2 μM TBBPA, 0.1 mg/L TiO2 NP, and their mixture from 8 to 120 h post fertilization (hpf), and motor/social behavioral assessments were conducted on embryos/larvae at different developmental stages. Our results showed that TBBPA/TiO2 NP single or co-exposures increased spontaneous movement, decreased touch response and swim speed, and affected social behaviors of light/dark preference, shoaling, mirror attack and social contact. In particular, many of these phenotypes were manifested with higher magnitude of changes from the mixture exposure. These behavioral deficits were also accompanied with increased cell death in olfactory region and neuromasts in the lateral line system, increased ROS in gallbladder, pancreas, liver, and intestine, as well as increased lipid peroxidation and decreased ATP levels in whole larval tissue homogenates. Further, genes coding for key cell apoptosis marker and antioxidant enzyme were significantly upregulated by these two chemicals, in particular to their mixture. Interestingly, the co-presence of TBBPA also increased the mean particle size of TiO2 NP in the exposure solutions and the TiO2 NP content in larval tissue. Together, our analysis suggests that TBBPA/TiO2 NP induced behavioral changes may be due to physical accumulation of these two chemicals in the target organs, and TiO2 NP may serve as carriers for increased accumulation of TBBPA. To conclude, we demonstrated that TBBPA/TiO2 NP together cause increased bioaccumulation of TiO2, and heightened responses in behavior, cell apoptosis and oxidative stress. Our findings also highlight the importance of toxicity assessment using chemical mixtures.
... Previous studies examining the biological uptake of NPs in fish have reported equivocal results, with some showing transport across fish epithelia in aqueous exposures to adult and [22][23][24] developing fish embryos, 25 while others have only reported deposition onto external tissues with minimal internal tissue accumulation. [26][27][28] The reasons for these discrepancies are varied and complex, but are likely related to the physicochemical differences between NPs used in different studies, and to the protein corona profile that forms on the surface of NPs. [29][30][31] Once internalized, protein coronas can direct varying cell responses, including transport through the circulatory system, tissue distribution, and cell internalization mechanisms. ...
Article
Immunological responses to nanoparticle (NP) exposures have been extensively reported usingin vitrocell models. Results show that metal-based NPs and NPs functionalized by a polyacrylic acid (PAA) polymer elicit both the activation of pro-inflammatory markers and the suppression of others. However, the translation of these immunotoxic effects to ecologicalin vivomodels has not been explored to the same extent, despite evidence showing that the vast majority of NPs that enter vascular circulation in fish are deposited into the kidneys and spleen, which are their major hematopoietic organs and where many immune cells reside. The long-term presence of NPs in these immune organs increases the opportunity to affect immune responses to both NPs and pathogens. In this study, we examined goldfish immunotoxicological responses to intravenously injected PAA-TiO2NPs (1 μg g⁻¹) by determining organ accumulation, depuration, tissue damage, and immune responsiveness in the kidneys, spleen, and isolated primary kidney neutrophils. Results showed significant deposition of Ti metal in the kidney, and especially spleen tissues that remained elevated for the 28 day study. Confocal imaging demonstrated that kidney neutrophils also internalized injected PAA-NPsin vivo, and there was increased lipid peroxidation in kidney and spleen tissues. Degranulatory and respiratory burst immune effector functions of isolated neutrophils were also potentiated at each time point, and there were significant changes in pro- and anti-inflammatory-related genes in hematopoietic organs of PAA-TiO2-injected fish. Finally, NP-injected fish also had significantly decreased capacity to clear a pathogenic (Mycobacterium chelonae) infection from the spleen following a 28 day pathogen challenge, suggesting a potential risk to long-term health and viability of NP-exposed fish.
... In most of these cases neurological damage is also reported. There are some reports failing to observe TiNP in the CNS [9][10][11]. This seemingly contradicting finding might have been resulted from different concentrations, duration of exposure, route of administration, different species, age of animals treated, and the ultrastructure of TiO 2 used. ...
Article
Titanium dioxide (TiO2) is a frequently used biomaterial, particularly in orthopedic and dental implants, and it is considered an inert and benign compound. This has resulted in toxicological scrutiny for TiO2 in the past decade, with numerus studies showing potential pathologic downstream effects. Herein we describe case report of a 77-year-old male with subacute CNS dysfunction, secondary to breakdown of a titanium-based carotid stent and leading to blood levels 1000 times higher (3 ppm) than the reported normal. We prospectively collected tissues adjacent to orthopedic implants and found a positive correlation between titanium concentration and time of implant in the body (r = 0.67, p < 0.02). Rats bearing titanium implants or intravascularly treated with TiO2 nanoparticles (TiNP) exhibited memory impairments. A human blood-brain barrier (BBB) in-vitro model exposed to TiNP showed paracellular leakiness, which was corroborated in-vivo with the decrease of key BBB transcripts in isolated blood vessels from hippocampi harvested from TiNP-treated mice. Titanium particles rapidly internalized into brain-like endothelial cells via caveolae-mediated endocytosis and macropinocytosis and induced pro-inflammatory reaction with increased expression of pro-inflammatory genes and proteins. Immune reaction was mediated partially by IL-1 and IL-6. In summary, we show that high levels of titanium accumulate in humans adjacent to orthopedic implants, and our in-vivo and in-vitro studies suggest it may be neurotoxic.
... The toxicity of TiO 2 NP in fish may be explained by the adsorption of the nanoparticles to the gill epithelial cells. Gill damaged by TiO 2 NP exposure has been associated with a decrease in arterial oxygen tension (PaO 2 ), leading to hypoxia condition in internal organs or imbalance in the body osmoregulation (Boyle et al. 2013b;Scown et al. 2009). The observation that toxic effects of MNPs in some instances do not necessarily require them being uptaken into internal tissues, questions further whether all the concepts applied to chemical toxicity hold for NPs. ...
Article
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.
... Engineered nanomaterials (ENMs) were reported to alter the behavior of fish species such as D. rerio and Oncorhynchus mykiss (Asmonaite et al. 2016;Boyle et al. 2013;Chen, Lin, and Tseng 2011;González et al. 2018;Powers et al. 2011;Truong et al. 2012), and AgNPs were shown to induce significant behavioral changes for D. rerio larvae at concentrations where no effects on survival or morphology were measurable (Powers et al. 2011). Further, distinct neurobehavioral effects were reported for different AgNP coatings and sizes, but also when comparing the behavioral responses of larvae being exposed to Ag + , suggesting that AgNPs exhibit the potential to act as a neurobehavioral disruptor (Powers et al. 2011 reported that AgNPs exposure impaired learning and social behaviors in zebrafish indicating a neurotoxic effect. ...
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The aim of this study was to determine the effects of silver nanoparticles (AgNPs; speciation: NM-300 K) in the lab on the behavior of larvae in European Whitefish (Coregonus lavaretus), a relevant model species for temperate aquatic environments during alternating light and darkness phases. The behavioral parameters measured included activity, turning rate, and distance moved. C. lavaretus were exposed to AgNP at nominal concentrations of 0, 5, 15, 45, 135, or 405 µg/L (n = 33, each) and behavior was recorded using a custom-built tracking system equipped with light sources that reliably simulate light and darkness. The observed behavior was analyzed using generalized linear mixed models, which enabled reliable detection of AgNP-related movement patterns at 10-fold higher sensitivity compared to recently reported standard toxicological studies. Exposure to 45 µg/L AgNPs significantly resulted in hyperactive response patterns for both activity and turning rates after an illumination change from light to darkness suggesting that exposure to this compound triggered escape mechanisms and disorientation-like behaviors in C. lavaretus fish larvae. Even at 5 µg/L AgNPs some behavioral effects were detected, but further tests are required to assess their ecological relevance. Further, the behavior of fish larvae exposed to 135 µg/L AgNPs was comparable to the control for all test parameters, suggesting a triphasic dose response pattern. Data demonstrated the potential of combining generalized linear mixed models with behavioral investigations to detect adverse effects on aquatic species that might be overlooked using standard toxicological tests.
... At day 10 significantly higher Ti levels were measured in the stomach and intestine of TiO 2 NPsexposed fish (uncoated and coated) compared to control levels ( Fig. 1a and b). These background levels in control tissues are expected due to the natural levels of Ti in fish and are consistent with levels measured in other studies using rainbow trout [26]. Uptake in the stomach followed the order TiO 2 -UNC (1.8 ± 0.1 mg Ti/kg) < TiO 2 -CIT (2.5 ± 0.3 mg Ti/kg) < TiO 2 -PEG with the highest concentration of Ti measured in TiO 2 -PEG NPs-exposed fish stomachs (2.9 ± 0.3 mg Ti/kg vs 0.85 ± 0.7 mg Ti/ kg (control fish)). ...
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Background This study was conducted to provide much needed information on the potential of low solubility, highly biodurable nanoparticles (NPs) (TiO2 and CeO2 NPs), to bioaccumulate in fish and to investigate the relationship between an engineered nanomaterials surface coating, uptake and biokinetics in vivo. Rainbow trout (Oncorhynchus mykiss) were fed diets spiked with uncoated or surface coated (polyethylene glycol (PEG) or citrate (CIT)) TiO2 and CeO2 NPs (100 mg NPs/kg feed) for 10 days and thereafter fish were allowed to depurate for 42 days. Special care was taken to measure the real dispersed and actual administered concentrations, taking into consideration any potential losses from leaching, and to characterise the form (size, aggregation state, charge) of the NPs to which the fish were exposed. Results The coatings had an influence on levels of uptake and distributions. Most notably a higher uptake of PEG and CIT coated TiO2 and CeO2 NPs compared to fish exposed to uncoated materials was observed. The elimination of any Ti from tissues was rapid during the first day of depuration, whereas Ce levels remained in fish tissues (stomach, intestine and liver) with differences in depuration and redistribution of the three types of CeO2 NPs. However, no bioaccumulation potential for both tested metal oxide NPs in fish irrespective of coatings is expected according to BMF values < 1. Conclusions Distinct uptake, distribution and depuration kinetics in rainbow trout have been evidenced for different metal oxide NPs (TiO2 and CeO2 NPs). Coatings influenced uptake and in some cases led to slower depuration and distinct distributions, but do not make the uncoated NPs studied bioaccumulative (BMF > 1). Graphical Abstract
... There is also evidence of indirect brain pathology, most likely arising from vascular injury and/or systemic hypoxia. Finally, effects on sense organs and changes in general behavior, due to altered sensory perception; as well as changes in the swimming behavior have been observed (Boyle et al., 2013). ...
Thesis
Due to their singular properties, the use of manufactured nanomaterials (NMs) has experienced a substantial success in the last decades. The growing production of these increasingly varied substances raises concern, in particular regarding their fate in environmental compartments and their potential effects on aquatic organisms. This thesis studied, in a systematic and innovative way, the interactions (adsorption, uptake, elimination and effects) of a set of twelve metal oxides NMs with different physicochemical characteristics, with different freshwater organisms representing primary producers (microalgae) and primary consumers (microinvertebrates). First, the interactions of three different species of microalgae with the NMs were characterized using a method developed for this purpose. Then, the uptake and elimination behaviors of the NMs in the filter-feeding microcrustacean D. magna were established. Subsequently, transcriptomic analyses allowed to determine the early molecular effects of NMs at the cellular and individual level of these organisms. Finally, the possibility of establishing relationships between the physicochemical properties of NMs and their behavior towards aquatic organisms was studied. The main findings of this work are finally intended to provide information on the importance of biological parameters in the NMs grouping processes of and to fill in the existing gaps in the risk assessment of NMs.
... In our case, induction of oxidative stress in fish gills and liver was observed in TiO 2 -NPs exposed fish. Our results suggest that gill damage and hypoxia could be the main causes of the reduced swimming speed observed in zebrafish adults, as was also reported by Boyle et al. (2013) for rainbow trout exposed to TiO 2 -NPs. In addition, the reduced MTT levels measured in zebrafish hemocytes, after TiO 2 -NPs exposure, denotes a reduced metabolic activity, that possibly affects fish swimming performance. ...
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Titanium dioxide nanoparticles (TiO2-NPs) are among the most popular manufactured and widely used nanoparticles. They are released into the environment, affecting terrestrial and aquatic ecosystems, with unexpected consequences to organisms and human health. The present study investigates the mediated toxicity imposed to the freshwater fish species, zebrafish (Danio rerio) and the prussian carp (Carassius gibelio), and to the terrestrial land snail Cornu aspersum, after their exposure to sublethal concentrations of TiO2-NPs. Oxidative, proteolytic, genotoxic and apoptotic parameters in fish liver and gills, as well as on snail hemocytes were studied and the swimming performance was estimated in order to (a) estimate and suggest the most susceptible animal, and (b) propose a common battery of biomarkers as the most suitable indicator for biomonitoring studies against TiO2-NPs. Our in vivo experiments demonstrated that NPs induced detrimental effects on animal physiology and swimming behavior, while no general pattern was observed in species and tissues responsiveness. Generally, TiO2-NPs seemed to activate a group of molecules that are common for aquatic as well as terrestrial animals, implying the existence of a conserved mechanism. It seems that after exposure to TiO2-NPs, a common mechanism is activated that involves the stimulation of immune system with the production of ROS, damage of lysosomal membrane, protein carbonylation, lipid peroxidation, DNA damage, following proteolysis by ubiquitin and finally apoptosis. Thus, the simultaneous use of the latter biomarkers could be suggested as a reliable multi parameter approach for biomonitoring of aquatic and terrestrial ecosystems against TiO2-NPs.
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Chapter
Proactive control measures to prevent exposure are often implemented initially until a more in depth understanding of nanomaterial risks are established. However, these precautionary measures may be costly and hamper innovation, commercialization, and development; therefore, it is preferable to advance knowledge to improve risk assessment and risk management for nanomaterials. The physical-chemical properties of nanomaterials can affect their toxicity, uptake, behavior, and fate. The proper measurement of physical-chemical properties helps associate them with toxicological outcomes, aid in grouping efforts for risk assessment, and support development of predictive risk assessment frameworks. Integration of life cycle considerations into risk assessment, such as through a screening level life cycle assessment (LCA) is important for responsible development of nanomaterials and nanoenabled products. Risk management efforts control and reduce risk, and are based on risk assessment, as well as environmental, health, and safety (EHS), economic, social, and political factors.
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Aquaculture has emerged as one of the world’s fastest-growing food industries in recent years, helping food security and boosting global economic status. The indiscriminate disposal of untreated or improperly managed waste and effluents from different sources including production plants, food processing sectors, and healthcare sectors release various contaminants such as bioactive compounds and unmetabolized antibiotics, and antibiotic-resistant organisms into the environment. These emerging contaminants (ECs), especially antibiotics, have the potential to pollute the environment, particularly the aquatic ecosystem due to their widespread use in aquaculture, leading to various toxicological effects on aquatic organisms as well as long-term persistence in the environment. However, various forms of nanotechnology-based technologies are now being explored to assist other remediation technologies to boost productivity, efficiency, and sustainability. In this review, we critically highlighted several ecofriendly nanotechnological methods including nanodrug and vaccine delivery, nanoformulations, and nanosensor for their antimicrobial effects in aquaculture and aquatic organisms, potential public health risks associated with nanoparticles, and their mitigation measures for sustainable management. Graphical abstract
Chapter
The increasing application and use of TiO 2 nanoparticles (NPs) ha ve led to higher production and subsequent release of these particles into the aquatic environment. Substances in surface waters will sorb to TiO 2 NPs, and sorption has implications on the fate, transport, and environmental consequences of both the substance and the NPs. In this chapter, we review sorption of organic substances with TiO 2 NPs in the aqueous phase, how sorption changes TiO 2 NPs physicochemistry, and how sorption can affect substance transport, decomposition, and bioavailability in aquatic organisms. Based on our research and a critical review of studies that have investigated sorption of organic substances with TiO 2 NPs, we conclude that constituents of the aquatic environment, such as ionic compounds and natural organic matter, can change surface physicochemistry of TiO 2 NPs, promote agglomeration of NPs, and influence the sorption capacity of TiO 2 NPs to sorb organic substances. Ultraviolet (UV) radiation can enhance the degradation of some organic substances sorbed on the surface area of TiO 2 NPs although degradation can also occur in dark conditions albeit at a much slower rate. The bioavailability of some organic substances can be influenced by the presence or absence of TiO 2 NPs, and measurement of bioavailability has been used as a sensitive method to inform on sorption of organic substances on TiO 2 NPs and their transport in the aqueous phase. Assessments of bioavailability have informed that sorption to NPs occurs and can facilitate transport of sorbent and exposure in aquatic organisms. The use of bioavailability measurements to investigate sorption of substances to NPs provides a unique and highly relevant analytical tool that enables interrogation directly within the aqueous phase (i.e. without the need for filtration or procedures that can disrupt sorption phenomenon). We investigated sorption of a photolabile organic compound, anthracene, on anatase TiO 2 NPs under ultraviolet A (UVA) light conditions. Sorption was assessed by evaluation of photo‐excited anthracene bioavailability in larval zebrafish. The reduction of bioavailable photo‐excited anthracene in the presence of TiO 2 NPs indicates sorption of anthracene or photo‐by‐products on TiO 2 NPs. Investigation of environmental factors that can influence sorption of organic contaminants on TiO 2 NPs and their transport in the aqueous phase is important for understanding environmental fate and the implications of TiO 2 NPs presence in the aquatic environment.
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Numerous ecotoxicology studies of carbon-based nanomaterials (CNMs) have been conducted in fishes; however, different approaches have been used to make CNM dispersions and dose tanks for aqueous exposures, and to prepare food containing CNMs for dietary studies. This diversity of experimental methods has led to conflicting results and difficulties in comparing studies. The objective of the present study was to evaluate intravenous injection of unfunctionalized CNMs in rainbow trout (Oncorhynchus mykiss), as a means of delivering a known internal dose, on tissue biochemistry and histopathological lesions; then, subsequently, to compare the results with our previous work on aqueous and dietary exposures of rainbow trout to CNMs. Rainbow trout were injected in the caudal vein with corn oil dispersions of 200 μg (approximately 1 μg g(-1)) of either the fullerene C60, single-walled carbon nanotubes (SWCNTs), or amorphous carbon black. After 96 h, injected fish were euthanized and tissue samples collected for biochemistry and histology. Histological examination of the kidney of fish injected intravenously indicated the presence of black material consistent with the injected carbon treatments. However, there were no additional lesions associated with CNM exposure compared to controls. There were also no significant changes in haematology, or ionoregulatory disturbance in blood plasma among the intravenously injected fish. Significant elevation in lipid peroxidation (thiobarbituric acid reactive substances TBARS) was detected only in kidney and spleen of fish injected with SWCNTs, but not the other carbon treatments. The elevated TBARS following injection contrasted with CNMs delivered via aqueous or dietary routes in our previous studies, suggesting that the latter exposure routes may not lead to absorption and toxicity in the internal tissues. Comparison of the effects of injected CNMs with aqueous and dietary CNMs exposures indicates that these materials are of minimal environmentally-relevant toxicity in rainbow trout.
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In the present study, fish Labeo rohita were exposed to 20, 50 and 100 µg/L of both Cu NPs and copper sulphate (CuSO4, bulk copper) for 24 h and hematological profiles were estimated. A significant (P< 0.01) change in the hemoglobin (Hb), hematocrit (Hct), white blood cells (WBC) and Mean Corpuscular Volume (MCV) levels were observed in all the three concentrations of both bulk and Cu NPs treated fish when compared to control groups. However a non significant change in red blood cells (RBC) (20 and 50 µg/L Cu NPs) and mean corpuscular hemoglobin (MCH) (20 and 50 µg/L bulk Cu) were observed. The alteration in Mean Corpuscular Hemoglobin Concentration (MCHC) value was found to be non significant both in bulk and Cu NPs treated fish. The alterations of these parameters can be used as a potential indicator to examine the health of fish in aquatic ecosystem contaminated with metal and metal based nanoparticles.
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The ever-growing production of engineered nanoparticles (NPs) for use in many agricultural, commercial, consumer, and industrial applications will lead to their accidental or intentional release into the environment. Potential routes of environmental exposure include manufacturing or transport spills, disposal of NP-containing products down the drain and/or in landfills, as well as direct usage on agricultural land. Therefore, NPs will inevitably contaminate aquatic environments and interact with resident organisms. However, there is limited information regarding the mechanisms that regulate NP transport into fish from the environment. Thus, our primary objective was to elucidate the mechanism(s) underlying cellular uptake and intracellular fate of 3-9nm poly (acrylic acid) NPs loaded with the fluorescent dye Nile red using a rainbow trout (Oncorhynchus mykiss) gill epithelial cell line (RTgill-W1). In vitro measurements with NP-treated RTgill-W1 cells were carried out using a combination of laser scanning confocal microscopy, flow cytometry, fluorescent biomarkers (transferrin, cholera toxin B subunit, and dextran), endocytosis inhibitors (chlorpromazine, genistein, and wortmannin), and stains (4', 6-diamidino-2-phenylindole, Hoechst 33342, CellMask Deep Red, and LysoTracker Yellow). Clathrin-mediated endocytosis (CME), caveolae-mediated endocytosis and macropinocytosis pathways were active in RTgill-W1 cells, and these pathways were exploited by the non-cytotoxic NPs to enter these cells. We have demonstrated that NP uptake by RTgill-W1 cells was impeded when clathrin-coated pit formation was blocked by chlorpromazine. Furthermore, colocalization analysis revealed a moderate positive relationship between NPs and LysoTracker Yellow-positive lysosomal compartments indicating that CME was the dominant operative mechanism involved in NP internalization by RTgill-W1 cells. Overall, our results clearly show that fish gill epithelial cells internalized NPs via energy-dependent endocytotic processes. This study enhances our understanding of complex NP-cell interactions and the results obtained in vitro imply a potential risk to aquatic organisms.
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In this study, we examined if rainbow trout chronically exposed to acetaminophen (10 and 30 μgL-1) showed histological changes that coincided with functional changes in the kidney, gill and liver. Histological changes in the kidney included movement and loss of nuclei, non-uniform nuclei size, non-uniform cytoplasmic staining, and loss of tubule integrity. Histological effects were more severe at the higher concentration and coincided with concentration dependent increases in urine flow rate and increased urinary concentrations of sodium, chloride, potassium, calcium, urea, ammonia, glucose, and protein. Yet, glomerular filtration rate was not altered with acetaminophen exposure. In the gill, filament end swelling, whole filament swelling, and swelling of the lamellae were observed in exposed fish. Lamellar spacing decreased in both exposure groups, but lamellar area decreased only with 30 μgL-1exposure. At faster swimming speeds, oxygen consumption was limited in acetaminophen exposed fish, and critical swimming speed was also decreased in both exposure groups. The liver showed decreased perisinusoidal spaces at 10 and 30 μgL-1acetaminophen, and decreased cytoplasmic vacuolation with 30 μgL-1acetaminophen. A decrease in liver glycogen was also observed at 30 μgL-1. There was no change in plasma concentrations of sodium, chloride, potassium, calcium, magnesium, and glucose with exposure, suggesting compensation for urinary loss. Indeed, an increase in Na+-K+-ATPase activity in the gills was found with 30 μgL-1acetaminophen exposure. Chronic exposure of rainbow trout to the environmentally relevant pharmaceutical acetaminophen, alters both histology and function of organs responsible for ion and nutrient homeostasis.
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The widespread commercial application of titanium dioxide nanoparticles (TiO2 NPs) leads to ubiquitous presence of TiO2 NPs in the aquatic environment, which highlights the necessity to determine their potential adverse effects on aquatic organisms. The developing nerve system is particularly susceptible to environment perturbation. However, few studies have explored the developmental neurobehavioral toxicity of TiO2 NPs, especially at smaller particle size ranges (≤ 20 nm) that have relatively longer retention time in the water column. In this study, zebrafish embryos were exposed to non-teratogenic concentrations of 0.1 and 1 mg/L TiO2 NPs (average size of 14-20 nm) from 8 to 108 hours post-fertilization (hpf) followed by various assessments at different time points up to 12 days post-fertilization (dpf). Our findings revealed that 1 mg/L TiO2 NPs perturbed the motor and social behaviors in larval zebrafish. These behavioral changes were characterized by decreased swimming speed in a locomotor response test at 5 dpf, increased travel distance in a flash stimulus test at 5 dpf, increased preference to the light zone in a light/dark preference test at 10 dpf, and increased mirror attack and percent time spent in the mirror zone in a mirror stimulus response assay at 12 dpf. Mechanistic examinations at 5 dpf revealed elevated cell apoptosis and oxidative stress. Cell apoptosis was characterized by increased acridine orange (AO) positive cells in the olfactory region and neuromasts of the lateral line system. Oxidative stress was characterized by increased lipid peroxidation, increased ROS production, and upregulated catalase (cat) gene expression. In addition, TiO2 NP exposure also upregulated genes associated with the developmental nervous system such as the growth associated protein 43 (gap43) and proliferating cell nuclear antigen (pcna). Our results suggest that the neurobehavioral changes in larvae exposed to 1 mg/L TiO2 NPs during early development may result from cell apoptosis and oxidative stress induced neuronal damages.
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Copper nanoparticles (CuNPs), a new pollutant in water environments, were widely used in various industrial and commercial applications. This study indicated that the presence of CuNPs exposure under environmental related concentration is an inducing factor that contributes to the fatty liver formation in Takifugu fasciatus. Furthermore, we explored the fatty liver formation mechanism. The results shown, (1) the cloned genes related to endoplasmic reticulum stress (ERS) (GRP78, IRE-1α, PERK, and ATF-6α) were highly expressed in the liver of T. fasciatus. (2) after 30-days exposure, CuNPs accumulated in the endoplasmic reticulum of liver and induced the appearance of ERS, then activated unfolded protein response (UPR) signaling pathway. Furthermore, the SREBP-1c pathway that plays a key role in lipid synthesis was activated. (3) by using 4-PBA and GSK inhibitors to respectively stimulate ERS and PKR-like ER kinase (PERK) through in vitro experiments, we confirmed that CuNPs induced the fatty liver formation in T. fasciatus triggered by the PERK-EIF2α pathway by activating the SREBP-1c pathway to promote fatty liver formation. This study provides a new perspective for identifying the pathogens of fatty liver formation, and adds to the knowledge of the ecological safety data service of CuNPs in water
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Antimony (Sb) is a toxic metal in aquatic ecosystems. In this study, the accumulation of aqueous Sb in the liver, brain, gills and muscle of zebrafish (Danio rerio) and its effect on genotoxicity, histopathology and ultrastructure alterations were evaluated. The fishes were exposed to different concentrations (0, 8.29, 16.58, 33.16 mg L⁻¹) of aqueous Sb for 18 days. The results showed that the order of Sb accumulation in different tissues was liver > gill > muscle > brain, and the accumulation increased with increasing Sb stress concentration. The mRNA expression levels of Nrf2, Cu/Zn-SOD, Mn-SOD, CAT and GPx genes showed different trends. In addition, significant histopathology and ultrastructure alterations were observed in the liver and gills exposed to Sb. Sb could accumulate in different tissues of zebrafish, inducing the expression of oxidative stress genes and activating antioxidant defense systems. Histological and ultrastructural changes could be used as valid biomarkers for the assessment of aqueous Sb contamination.
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Rainbow trout with a cautery-induced 30 % reduction in functional gill area showed significant proportional reductions in maximum oxygen consumption (Vo 2 m«x) m comparison to controls, but oxygen consumption at rest and at sub-critical swimming speeds was not affected. This corroborates suggestions that total gill area is utilized for oxygen uptake only under conditions of maximum aerobic demand. During swimming trials, hyperoxia (P O2 300mmHg) neither increased V o , m u of control fish nor compensated for the reduced V O2mlLX apparent in fish with reduced gill area. Therefore a direct limitation on oxygen uptake at the gills is implied.
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It is axiomatic in modern zoology to suppose that natural selection has shaped animals so as to perform their functions as efficiently as possible. Any adaptation, physiological or behavioural, which can be shown to save energy, is assumed to be adaptive. A fish, for example, that uses less energy for ventilating its gills than another of the same species will be able to use the energy saved to grow faster and produce more eggs. The efficient genotype is therefore selected (Alexander, 1967). It is now thought that much of animal foraging behaviour can be explained by so-called ‘optimal foraging theory’, whereby the animal behaves in such a manner as to maximize the ratio of energy income over energy expenditure.
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This study tests the hypothesis that rainbow trout (Oncorhynchus mykiss) compensate for the metabolic cost of dietary Cu exposure by reducing swimming activity at particular times during the diel cycle. Fish were exposed to excess dietary Cu for three months (726 mg Cu·kg–1 dry weight) and simultaneously oxygen consumption (MO2) and spontaneous swimming activity were measured. Rhythmicity in swimming activity was examined by videorecording fish behaviours for 48 h. Standard metabolic rate estimates (RS) of 7.2 and 8.7 mmol O2·kg–1·h–1 (15°C) were measured for control and Cu-exposed fish, respectively. MO2 was higher in Cu-exposed fish at any chosen speed compared with control Cu-exposed trout, which decreased activity (mean speed) by at least 75%, spent more time at lower speeds, and lost circadian periodicity in these parameters compared with controls. Mean growth rates were normal, although Cu-exposed fish showed a narrower range of body weights and fewer mortalities than control groups, suggesting a suppression in social behaviour in Cu-exposed fish. Overall, the increased metabolic cost of swimming in Cu-exposed fish was fully compensated by a reduction in activity, particularly at night and dawn. However, this behavioural strategy suggests that spatial and temporal aspects of ecologically important social behaviours may be compromised in Cu-exposed fish.
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While the existence of dominance hierarchies within natural populations of salmonids is well known, little is known about the physiological consequences of these social interactions. To investigate such physiological effects, replicate groups of four brown trout (Salmo trutta) were held under simulated natural conditions in an artificial stream tank. Behavioural observations allowed the fish to be ranked for dominance. After two weeks, physiological status was assessed through measurements of specific growth rate, condition factor, plasma cortisol and ion concentrations, haematocrit, leucocrit, hepatosomatic index, hepatic glycogen concentration, interrenal cell nuclear area and gill epithelium chloride cell density. Weight gain in the first-ranking (dominant) fish was significantly higher than in the second-ranking fish. In addition, the condition factor of the second-ranking fish decreased over the experimental period while those of the first- and third- ranking fish increased, resulting in significant differences among the three groups. The only other physiological parameter which varied significantly among the ranked fish was chloride cell density, which was significantly higher in the second-ranking fish than in the dominant fish. Cortisol concentrations were low in all fish and did not vary significantly with dominance status. Overall, the least beneficial position, in physiological terms, appears to be the second rank in the dominance hierarchy.
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Manufactured nanomaterials (NM) are already used in consumer products and exposure modelling predicts releases of ng to low µg l(-1) levels of NMs into surface waters. The exposure of aquatic ecosystems, and therefore fishes, to manufactured NMs is inevitable. This review uses a physiological approach to describe the known effects of NMs on the body systems of fishes and to identify the internal target organs, as well as outline aspects of colloid chemistry relevant to fish biology. The acute toxicity data, suggest that the lethal concentration for many NMs is in the mg l(-1) range, and a number of sublethal effects have been reported at concentrations from c. 100 µg to 1 mg l(-1). Exposure to NMs in the water column can cause respiratory toxicity involving altered ventilation, mucus secretion and gill pathology. This may not lead, however, to overt haematological disturbances in the short term. The internal target organs include the liver, spleen and haematopoietic system, kidney, gut and brain; with toxic effects involving oxidative stress, ionoregulatory disturbances and organ pathologies. Some pathology appears to be novel for NMs, such as vascular injury in the brain of rainbow trout Oncorhynchus mykiss with carbon nanotubes. A lack of analytical methods, however, has prevented the reporting of NM concentrations in fish tissues, and the precise uptake mechanisms across the gill or gut are yet to be elucidated. The few dietary exposure studies conducted show no effects on growth or food intake at 10-100 mg kg(-1) inclusions of NMs in the diet of O. mykiss, but there are biochemical disturbances. Early life stages are sensitive to NMs with reports of lethal toxicity and developmental defects. There are many data gaps, however, including how water quality alters physiological responses, effects on immunity and chronic exposure data at environmentally relevant concentrations. Overall, the data so far suggest that the manufactured NMs are not as toxic as some traditional chemicals (e.g. some dissolved metals) and the innovative, responsible, development of nanotechnology should continue, with potential benefits for aquaculture, fisheries and fish health diagnostics.
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Our laboratory recently reported gut pathology following incidental ingestion of titanium dioxide nanoparticles (TiO(2) NPs) during aqueous exposures in trout, but there are almost no data on dietary exposure to TiO(2) NPs in fish. The aim of this experiment was to observe the sub-lethal effects of dietary exposure to TiO(2) NPs in juvenile rainbow trout (Oncorhynchus mykiss). Stock solutions of dispersed TiO(2) NPs were prepared by sonication without the use of solvents and applied to a commercial trout diet. Fish were exposed in triplicate to either, control (no added TiO(2)), 10, or 100 mg kg(-1) TiO(2) NPs diets for 8 weeks followed by a 2 week recovery period where all fish were fed the control diet. TiO(2) NPs had no impact on growth or nutritional performance, and no major disturbances were observed in red or white blood cell counts, haematocrits, whole blood haemoglobin, or plasma Na(+). Ti accumulation occurred in the gill, gut, liver, brain and spleen during dietary TiO(2) exposure. Notably, some of these organs, especially the brain, did not clear Ti after exposure. The brain also showed disturbances to Cu and Zn levels (statistically significant at weeks 4 and 6; ANOVA or Kruskal-Wallis, P < 0.05) and a 50% inhibition of Na(+)K(+)-ATPase activity during TiO(2) NP exposure. Na(+)K(+)-ATPase activity was unaffected in the gills and intestine. Total glutathione in the gills, intestine, liver and brain were not affected by dietary TiO(2) NPs, but thiobarbituric acid reactive substances (TBARS) showed up to 50% decreases in the gill and intestine. We conclude that TiO(2) NPs behave like other toxic dietary metals where growth rate and haematology can be protected during sub-lethal exposures, but in the case of TiO(2) NPs this may be at the expense of critical organs such as the brain and the spleen.
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Our recent work suggests limited uptake of unstabilized metal oxide nanoparticles via water into fish, however, some other studies have indicated such exposures can induce oxidative stress. To investigate tissue distribution and toxicity of titanium dioxide (TiO2) nanoparticles that may enter into fish, we conducted a series of injection studies. Rainbow trout (Oncorhynchus mykiss) were intravenously injected with 100 μg TiO2 nanoparticles and the content of titanium in blood, brain, gills, liver, and kidney quantified at time points between 6 h and 90 days using inductively coupled plasma optical emission spectroscopy. Injected Ti was concentrated in the kidneys and remained there up to 21 days, however, there was evidence of clearance of TiO2 at 90 days. Ti accumulation in the liver was 15 times lower than in the kidney with no apparent clearance. Using TEM we showed nanoparticles were localized in tissue vesicles surrounding the kidney tubules. In a second injection study, rainbow trout were injected with 100 μg TiO2 and plasma samples from individual fish analyzed for total protein and creatinine content at time points between 6 h and 21 days to assess for possible effects on kidney function. No effect of TiO2 on total plasma protein content or creatinine concentrations were found indicating that neither urine production nor glomerular filtration rate were affected. We conclude that in trout upon a single high dose exposure of TiO2 nanoparticles via the bloodstream, TiO2 accumulates in the kidneys but has minimal effect on kidney function.
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A technique for measuring the patterns and levels of swimming activity of unrestrained fish in their natural environment during a period of 24 h is described. The fish were marked with small tags which emitted continuous ultrasonic signals by which they could be located and tracked using submerged, remotely controlled, directional hydrophones. Preliminary results obtained from 2 brown trout (Sahno trutta) showed a pronounced diurnal activity pattern and remarkably low swimming activity levels.
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The aim of this study was to obtain a holistic view of the sublethal toxic responses, and compensations, of fish exposed to Cu in the diet. Rainbow trout were fed to appetite on either a Cu-loaded diet (500 mg Cu kg−1 dw) or a control diet (11.9 mg Cu kg−1 dw) for 3 months. Nutritional performance, blood and muscle chemistry, histology, respiration, and swimming behaviour were measured. Copper concentration in intestine and liver of exposed fish was 16 and 2.5 times greater than in controls respectively, confirming oral Cu exposure. [Cu] remained low in the gills of fish irrespective of Cu treatment (<0.096 μmol g−1 dw). Hepatic and intestinal metallothionien levels increased 8- and 1.5-fold, respectively, in Cu-treated fish compared to controls. Growth rate, appetite, food conversion ratios, carcass composition, oxygen consumption and ventilation rate in exposed fish were not different from controls. There were no treatment related changes in serum chemistry (glucose, triglycerides, protein, Na, K, Hb) or the mineral composition of skeletal muscle (Ca, Mg, Zn, Na, or K). However, quantitative histology showed a 9% increase in gill secondary lamellae length, together with lipid depletion in the livers of copper treated fish compared to controls. Routine swimming activity was affected significantly by oral Cu exposure. Time spent swimming was 35% lower in Cu-exposed fish after 3 months, while total distance moved was reduced by only 21% because mean swimming speed was 12% higher in contaminated fish. Maximum speeds attained by exposed fish were not different compared to controls. Exposed fish lowered activity overall by decreasing time spent swimming at low (1–17 cm s−1) and medium speeds (17–40 cm s−1), whilst increasing proportionately time spent fast swimming (40–58 cm s−1). These results are discussed in terms of sub-lethal oral Cu affecting the partitioning of energy utilisation between locomotion and maintenance metabolism by trout in a physiological drive towards invariant growth rates.
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A photometric method for determining acetylcholinesterase activity of tissue extracts, homogenates, cell suspensions, etc., has been described. The enzyme activity is measured by following the increase of yellow color produced from thiocholine when it reacts with dithiobisnitrobenzoate ion. It is based on coupling of these reactions: The latter reaction is rapid and the assay is sensitive (i.e. a 10 μ1 sample of blood is adequate). The use of a recorder has been most helpful, but is not essential. The method has been used to study the enzyme in human erythrocytes and homogenates of rat brain, kidney, lungs, liver and muscle tissue. Kinetic constants determined by this system for erythrocyte eholinesterase are presented. The data obtained with acetylthiocholine as substrate are similar to those with acetylcholine.
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Abstract Little is known about the effects of manufactured nanomaterials on the function of nerves. The experiment aimed to test the effects of three different nanomaterials (1 mg l(-1) of TiO(2) NPs, Ag NPs or SWCNT) on the compound action potential of the shore crab (Carcinus maenas) compared with an appropriate bulk powder or metal salt control (bulk TiO(2) powder, AgNO(3) and carbon black respectively). In single action potential recordings, there were no effects of any of the nanomaterials on the peak amplitude, duration, rate of rise (depolarisation), or rate of decrease (repolarisation) of the compound action potential in crab saline, despite settling of each nanomaterial directly onto the nerve preparation. The ability of the crab nerve to be stimulated to tetanus was also unaffected by exposure to the nanomaterials compared with the appropriate bulk powder or metal salt control. Solvent controls with sodium dodecyl sulfate (SDS) also had no effect on action potentials. Overall, the study concludes that there were no effects of the materials at the concentrations tested on the compound action potential of the shore crab in physiological saline.
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The use of nanoscale materials is growing exponentially, but there are also concerns about the environmental hazard to aquatic biota. Metal-containing engineered nanoparticles (NPs) are an important group of these new materials, and are often made of one metal (e.g., Cu-NPs and Ag-NPs), metal oxides (e.g., ZnO and TiO(2) NPs), or composite of several metals. The physiological effects and toxicity of trace metals in the traditional dissolved form are relatively well known and the overall aim of this review was to use our existing conceptual framework of metal toxicity in fish to compare and contrast the effects of nanometals. Conceptually, there are some fundamental differences that relate to bioavailability and uptake. The chemistry and behaviour of nanometals involves dynamic aspects of aggregation theory, rather than the equilibrium models traditionally used for free metal ions. Some NPs, such as Cu-NPs, may also release free metal ions from the surface of the particle. Biological uptake of NPs is not likely via ion transporters, but endocytosis is a possible uptake mechanism. The body distribution, metabolism, and excretion of nanometals is poorly understood and hampered by a lack of methods for measuring NPs in tissues. Although data sets are still limited, emerging studies on the acute toxicity of nanometals have so far shown that these materials can be lethal to fish in the mg-μgl(-1) range, depending on the type of material. Evidence suggests that some nanometals can be more acutely toxic to some fish than dissolved forms. For example, juvenile zebrafish have a 48-h LC(50) of about 0.71 and 1.78mgl(-1) for nano- and dissolved forms of Cu respectively. The acute toxicity of metal NPs is not always explained, or only partly explained, by the presence of free metal ions; suggesting that other novel mechanisms may be involved in bioavailability. Evidence suggests that nanometals can cause a range of sublethal effects in fish including respiratory toxicity, disturbances to trace elements in tissues, inhibition of Na(+)K(+)-ATPase, and oxidative stress. Organ pathologies from nanometals can be found in a range of organs including the gill, liver, intestine, and brain. These sublethal effects suggest some common features in the sublethal responses to nanometals compared to metal salts. Effects on early life stages of fish are also emerging, with reports of nanometals crossing the chorion (e.g., Ag-NPs), and suggestions that the nano-forms of some metals (Cu-NPs and ZnO NPs) may be more toxic to embryos or juveniles, than the equivalent metal salt. It remains possible that nanometals could interfere with, and/or stimulate stress responses in fish; but data has yet to be collected on this aspect. We conclude that nanometals do have adverse physiological effects on fish, and the hazard for some metal NPs will be different to the traditional dissolved forms of metals.
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Nanoparticles (NPs) are reported to be a potential environmental health hazard. For organisms living in the aquatic environment, there is uncertainty on exposure because of a lack of understanding and data regarding the fate, behavior, and bioavailability of the nanomaterials in the water column. This paper reports on a series of integrative biological and physicochemical studies on the uptake of unmodified commercial nanoscale metal oxides, zinc oxide (ZnO), cerium dioxide (CeO(2)), and titanium dioxide (TiO(2)), from the water and diet to determine their potential ecotoxicological impacts on fish as a function of concentration. Particle characterizations were performed and tissue concentrations were measured by a wide range of analytical methods. Definitive uptake from the water column and localization of TiO(2) NPs in gills was demonstrated for the first time by use of coherent anti-Stokes Raman scattering (CARS) microscopy. Significant uptake of nanomaterials was found only for cerium in the liver of zebrafish exposed via the water and ionic titanium in the gut of trout exposed via the diet. For the aqueous exposures undertaken, formation of large NP aggregates (up to 3 mum) occurred and it is likely that this resulted in limited bioavailability of the unmodified metal oxide NPs in fish.