Comparison of in vitro and in vivo acute toxicity assays in Etroplus suratensis (Bloch, 1790) and its three cell lines in relation to tannery effluent

Hitting two targets with one shot on pesticide genotoxicity assessment - Identifying risk while unveiling ex vivo approach as a throughput tool in gill-breathing animals

Pesticides in the environment often compromise the ecosystem, thus requiring reliable approaches to assess their effects. Commonly used approaches, such as in vivo, come with several disadvantages, namely in the light of the 3 R's policy. Seeking for accurate and ethical approaches, this study intended to validate the ex vivo technique as an alternative, and to assess the genotoxicity of chemically-based pesticides and a biopesticide. The ex vivo approach was applied to gill cells of Procambarus clarkii for 2, 4 and 8 h. Cell viability and DNA integrity were evaluated to determine the applicability of this approach. Crayfish gill cells only showed to be suitable for exposures of 2 h. Accordingly, genotoxicity was evaluated in gill cells exposed, for 2 h, to environmentally relevant concentrations of the chemically-based pesticides dimethoate (20 µg L-1), imazalil (160 µg L-1) and penoxsulam (23 µg L-1), as well as to the bioinsecticide Turex® (25, 50, 100, 200 and 400 µg L-1). Every chemically-based pesticide demonstrated to be genotoxic, despite not inducing oxidative DNA damage. On the other hand, Turex® showed no genotoxic effects. Overall, the ex vivo approach demonstrated to be possible and practical to implement, improving the number of outcomes with a lower number of organisms. The findings from the screening test suggest that biological pesticides may pose a lower risk to non-target organisms compared to chemically-based pesticides.

A comparative study on targeted gene expression in zebrafish and its gill cell line exposed to chlorpyrifos

Chlorpyrifos (CPF) is an organophosphorus-based insecticide, which is known to pose a serious risk to aquatic animals. However, the mechanisms of CPF toxicity in animals still remain unclear. The present investigation aimed to compare the potential effects of CPF in zebrafish (Danio rerio) and its gill cell line (DrG cells). Based on the in vivo study, the LC50 was calculated as 18.03 µg/L and the chronic toxic effect of CPF was studied by exposing the fish to 1/10th (1.8 µg/L) and 1/5th (3.6 µg/L) of the LC50 value. Morphological changes were observed in fish and DrG cells which were exposed to sublethal concentrations of CPF. The results of MTT and NR assays showed significant decline in the survival of cells exposed to CPF at 96 h. The production of reactive oxygen species in DrG cells and expression levels of antioxidant markers, inflammatory response genes (cox2a and cox2b), cyp1a, proapoptotic genes (bax), antiapoptotic gene (bcl2), apoptotic genes (cas3 and p53), and neuroprotective gene (ache) were determined in vivo using zebrafish and in vitro using DrG cells after exposure to CPF. Significant changes were found in the ROS production (DrG cells) and in the expression of inflammatory, proapoptotic, and apoptotic genes. This study showed that DrG cells are potential alternative tools to replace the use of whole fish for toxicological studies.

Understanding contaminant exposure risks in nesting Loggerhead sea turtle populations

Queensland loggerhead turtle nest numbers at Mon Repos (MR) indicate population recovery that doesn't occur at Wreck Island (WI). Previous research illustrated that MR and WI turtles forage in different locations, potentially indicating risks differences. Blood, scute, and egg were collected from turtles nesting at MR and WI, with known foraging sites (from concurrent studies). Trace element and organic contaminants were assessed via acid digestion and in vitro cytotoxicity bioassays, respectively. WI turtles had significantly higher scute uranium and blood molybdenum compared to MR turtles, and arsenic was higher in WI turtles foraging north and MR turtles foraging south. Egg and blood titanium, manganese, cadmium, barium, lead, and molybdenum, and scute and egg selenium and mercury significantly correlated. Blood (75 %) extracts produced significant toxicity in vitro in turtle fibroblast cells. In conclusion, reducing chemical exposure at higher risk foraging sites would likely benefit sea turtles and their offspring.

Review of ecologically relevant in vitro bioassays to supplement current in vivo tests for whole effluent toxicity testing - Part 1: Apical endpoints

Whole effluent toxicity (WET) testing is commonly used to ensure that wastewater discharges do not pose an unacceptable risk to receiving environments. Traditional WET testing involves exposing animals to (waste)water samples to assess four major ecologically relevant apical endpoints: mortality, growth, development, and reproduction. Recently, with the widespread implementation of the 3Rs to replace, reduce and refine the use of animals in research and testing, there has been a global shift away from in vivo testing towards in vitro alternatives. However, prior to the inclusion of in vitro bioassays in regulatory frameworks, it is critical to establish their ecological relevance and technical suitability. This is part 1 of a two-part review that aims to identify in vitro bioassays that can be used in WET testing and relate them to ecologically relevant endpoints through toxicity pathways, providing the reader with a high-level overview of current capabilities. Part 1 of this review focuses on four apical endpoints currently included in WET testing: mortality, growth, development, and reproduction. For each endpoint, the link between responses at the molecular or cellular level, that can be measured in vitro, and the adverse outcome at the organism level were established through simplified toxicity pathways. Additionally, literature from 2015 to 2020 on the use of in vitro bioassays for water quality assessments was reviewed to identify a list of suitable bioassays for each endpoint. This review will enable the prioritization of relevant endpoints and bioassays for incorporation into WET testing.

Temporal changes in chemical contamination of green turtles (Chelonia mydas) foraging in a heavily industrialised seaport

Port Curtis, a major shipping port, has undergone significant expansion in the last decade, with plans for further development into the future. These activities may result in an increase of contaminant concentrations, threatening local wildlife including sea turtles. This study used a species-specific in vitro bioassay to examine spatial and temporal differences in exposure to, and effects of, organic contaminants in green sea turtles foraging in Port Curtis. Blood was collected from 134 green sea turtles (Chelonia mydas) from five locations in the port over four years. Organic contaminants were extracted from blood, and the cytotoxicity of the extracts to primary green sea turtle cells was assessed. Results indicated spatially similar chemical contamination throughout Port Curtis, at levels significant to sea turtle health, and with signs that chemical contamination may be increasing over time. These results can provide valuable information on the health of green turtles as further development occurs.

Fish cell lines as screening tools to predict acute toxicity to fish of biocidal active substances and their relevant environmental metabolites

Biocidal substances and their environmental relevant metabolites are highly toxic for fish. However, an important scarcity of toxicity data for metabolites is recognised. This article provides new data about the toxicity to fish of these compounds and evaluates the potential use of fish cell lines as screening tools to assess the acute toxicity of these compounds in fish. To this aim, acute toxicity of 7 substances was tested in Oncorhynchus mykiss (OECD TG203) and cytotoxicity of 16 substances was assessed in fish cell lines from two species; Poeciliopsis lucida (PLHC-1) and O. mykiss (RTH-149, RTG-2 and RTgill-W1) performing three cytotoxicity tests: Alamar-Blue, 5-carboxyfluorescein diacetate, acetoxymethyl ester and Neutral Red Uptake. Additionally, in vitro and in vivo data from the LIFE-COMBASE database were included in a dataset finally comprising 33 biocides and 14 metabolites. Hazard data were categorized into 4 toxicity groups, according to the intervals established in Regulation (EC) 1272/2008. Finally, the Spearman correlation test was performed and coincidences between in vitro-in vivo data established. In vitro and in vivo results revealed a high positive correlation, with a complete coincidence for 56.5% of the substances, a 2% of false positives (non-toxic in vivo) and a 13% of false negatives (toxic in vivo) for the 4 toxicity categories. However, when results were grouped in toxic or non-toxic coincidence was obtained for 85% of the substances. In conclusion, although fish denote a greater sensitivity, the use of at least two fish cell lines and three cytotoxicity endpoints appear to be valid approaches for fish acute toxicity screening of biocides and their metabolites.

Impact of post-tanning chemicals on the pollution load of tannery wastewater

The leather industry uses a large amount of chemicals to transform a raw hide into finished leather. Chemicals are not fully taken up by leather and thus end up in tannery wastewater. Physicochemical and toxicological characterization of tannery effluents has been widely assessed. However, the characterization of processing chemicals and their relation to the pollution load of effluents remains unknown. Thus, this study aimed to assess a physicochemical and cytotoxic characterization of chemicals used in the leather post-tanning process and to evaluate the contribution of each chemical to the pollution load of raw wastewater. This study was performed using a leather post-tanning formulation applied by a large tannery located in Brazil. Deacidulation agents caused high conductivity and dissolved solids in wastewater. Retanning agents (natural and synthetic tannins) were responsible for the largest inorganic pollution load, and synthetic tannins were more toxic than natural ones. Fatliquoring agents released the highest chemical oxygen demand load in wastewater and they were the chemical group that presented the highest toxicity. Fixing agent and black dye provided inorganic pollution load to wastewater, and nitrogen pollution of wastewater was mainly related to the neutralizing retanner and the black dye.

Safety assessment of antibiotic administration by magnetic nanoparticles in in vitro zebrafish liver and intestine cultures

Different in vitro models have been suggested to replace in vivo studies. In vitro studies are of great interest and give the opportunity to analyze cellular responses in a closed system with stable experimental conditions and to avoid direct animal exposure and distress during the experiments. These methods are useful to test drugs and chemicals toxicity in order to better understand their environmental impact. In the present study, fish organ cultures have been used to test different oxytetracycline exposure methods, including oxide nanoparticles (IONPs), using zebrafish as experimental model. Results showed that oxytetracycline accumulation at the end of the experiment (24 h) in the exposed organs did not show any significant difference in the analyzed samples and was not dependent on the exposure way (free or IONPs-bound oxytetracycline). However, as regards molecular analysis, the different exposure ways tested in this study showed some differences in the expression of genes involved in stress response. The present data did not completely agree with a previous in vivo study performed in zebrafish using IONPs, underlying that replacement of in vivo models with in vitro studies cannot always represent the complexity of interactions typical of a biological system.

Behavioral toxicity of tannery effluent in zebrafish (Danio rerio) used as model system

The ecotoxicity of untreated tannery effluent (UTE) in several animal models has been reported; however, its effects on fish behavior, and neurotoxicity, remain unknown. Thus, the hypothesis that the chronic exposure to UTE can induce behavioral changes in adult zebrafish (Danio rerio) representatives, even when it is highly diluted in water, was tested. Animals exposed to 0.1% and 0.3% UTE for 30 days showed behavioral changes in visual social preference tests through their co-specific and antipredator defensive responses, which had indicated neurotoxic actions. Zebrafish exposed to UTE appeared to have not co-specific preference when it is paired with Poecilia sphrenops. In addition, only animals in the control group showed aversive behavior in the presence of the herein used predatory stimulus (Oreochromis niloticus). However, Cr, Na and Mg bioaccumulation was higher in zebrafish exposed to 0.1% and 0.3% UTE, although anxiogenic and anxiolytic effects were not observed in the models exposed to UTE in the novel tank diving or aggressiveness-increase-in-the-mirror tests. This outcome allowed associating the exposure to the pollutant and bioaccumulation with the observed behavioral changes. The present study is pioneer in scientifically evidencing the sublethal impact caused by chronic exposure to UTE in experimental environment simulating realistic aquatic pollution conditions. Accordingly, results in the current research should motivate further investigations to broaden the knowledge about the real magnitude of UTE biological impacts on the aquatic biota.

Theoretical consideration on the prediction of in vivo toxicity from in vitro toxicity: Effect of bio-uptake equilibrium, kinetics and mode of action

Although in vitro assay is an ideal alternative method for the in vivo toxicity prediction, different in vivo-in vitro correlations have been observed for the toxicity endpoints obtained from different levels of species. In this paper, theoretical in vivo-in vitro toxicity correlations have been developed for cytotoxicity versus human, mammalian and fish toxicity, respectively. These theoretical models were then used to investigate the correlations and the influencing factors between in vivo and in vitro toxicity. Bio-uptake equilibrium theory can well explain why there is a significant correlation between fish and cell toxicity (R² = 0.70); why human toxicity is very close to fish toxicity; and why hydrophobic compounds exhibit relatively greater toxicity than reactive or specifically-acting compounds to human and fish as compared to cells. The kinetic theory can well explain why there is a very poor relationship between mammal and cell toxicity (R² = 0.44). This paper reveals that polar and ionized compounds can more easily pass through cell membrane and have greater bioconcentration potential. Increasing of hydrophobicity and ionization can increase the cytotoxicity. Inclusion of descriptors representing hydrophobicity, ionization, acidity and absorption into the correlation equations can significantly improve the correlations of cytotoxicity with human and fish toxicity (R² > 0.8), but not with mammal toxicity (R² = 0.49). These descriptors reflect the differences of the toxicodynamics and toxicokinetics between cells and organisms.

Dietary ascorbic acid reduced micronucleus and nuclear abnormalities in Clarias gariepinus (Burchell 1822) exposed to hospital effluent

Hospital effluents contain myriad of mutagens and genotoxins capable of increasing DNA damage in aquatic biota. African mudfish, Clarias gariepinus, are exposed to genotoxins when cultured in swamps and derelict water bodies often contaminated by effluents. Moreover, its DNA is susceptible to xenobiotic-induced lesions since it lacks L-gulonolactone oxidase and hence cannot synthesize L-ascorbic acid. This study investigated 96-h acute toxicity and protective effects of dietary ascorbic acid (AA) against micronucleus (MN) and abnormal nuclear (NAs) formation in C. gariepinus exposed to sub-lethal concentrations of hospital effluent. Six concentrations (0.5-3.0%) of the effluent were selected to determine the 96-h acute toxicity of the effluent in C. gariepinus, after range finding test. Fish were exposed to sub-lethal concentrations (0.08-1.30%) of the 96 h LC₅₀. Two other groups were exposed to the 96 h LC₅₀ (1.30%) of the effluent +50 and +100 mg/kg of dietary ascorbic for 7 days, and MN and NAs assessed in peripheral erythrocytes. The 96 h LC₅₀ (1.30%) was 1.18 times more toxic than the 24 h LC₅₀ (1.54%), indicating that the toxicity of the effluent increased with exposure duration. MN, nuclear bud, enucleated, fragmented nucleus (apoptosis), and necrotic erythrocytes significantly increase in effluent treated fish. Dietary AA reduced MN from 6.35-fold (1.30% treated group) to 3.72-fold (1.30% + 50 mg AA) and 3.54-fold (1.30% + 100 mg AA). Also, AA reduced total NAs from 2.26-fold (1.30%) to 1.40-fold (1.30% + 50 mg AA) and 1.06-fold (1.30% + 100 mg AA) compared to the control. Heavy metals and physicochemical parameters analyzed in the tested effluent possibly induced the mortality and cytogenotoxicity in C. gariepinus, and this was ameliorated by dietary AA.

Application of fish cell lines for evaluating the chromium induced cytotoxicity, genotoxicity and oxidative stress

In the present study, we hypothesize that cytotoxicity, genotoxicity and oxidative stress play a key role in chromium induced toxicity in SISS, SISK, IEE, IEK, IEG, SICH and ICG cell lines after 24 h exposure. Three fish species namely Lates calcarifer, Etroplus suratensis and Catla catla were exposed to the concentrations of 0, 10, 20, 30, 40 and 50 mg/L of chromium for 96 h under static conditions for conducting acute toxicity tests. LC₅₀ was then calculated. The percentage cell survival was assessed by multiple endpoints such as MTT, NR, AB and CB assays in the seven fish cell lines exposed to different concentrations of chromium and EC₅₀ values of all the four endpoints were calculated. High significances were noted in the correlations between each in vitro cytotoxicity assays and in vivo mortality data. Cell shrinkage, cell detachment, vacuolations and cell swelling at the highest concentration of chromium (50 mg/L) were seen on microscopic examination of cell morphology. Comet assay and Hoechst staining were carried out to assess DNA damage and nuclear fragmentation in the seven fish lines exposed to chromium. The results of antioxidant parameters obtained indicate a significant reduction in the level of catalase, superoxide dismutase, glutathione S-transferase and Glutathione peroxidase, and increased level of lipid peroxidation in all the cell lines exposed to chromium. These results confirm that fish cell lines could be used as an alternative to whole fish for cytotoxicity, genotoxicity and oxidative stress assessment in chromium toxicity studies.

The genotoxicity and cytotoxicity of tannery effluent in bullfrog (Lithobates catesbeianus)

Some of the most polluting activities occur in bovine skin processing. Tannery generates effluents containing high concentrations of heavy metals and organic compounds. The phases composing the leather production process generate a large volume of tannery effluents that are often discarded in aquatic environments without any previous treatment. However, the effect these xenobiotics have on adult representatives belonging to the class Amphibia remains unknown. Thus, the aim of the present study is to assess the geno- and cytotoxic effects of tannery effluent on adult male bullfrogs (Lithobates castesbeianus) exposed to it. Accordingly, the animals were divided into the following groups: negative control (tannery effluent-free water), positive control (cyclophosphamide), and effluent (water added with 5% tannery effluent). The animals were euthanized for blood collection, and erythrocyte analyses were conducted after 35 and 90 days of exposure. The micronuclei (MN) frequency and the frequency of other nuclear abnormalities in each of the animals in the experimental groups were assessed in 2000 erythrocytes. According to the present results, the exposure to tannery effluents increased MN frequency as well as other nuclear abnormalities (i.e., lobed nuclei, binucleated cell, kidney-shaped nuclei, notched nuclei, and apoptotic cell) in the erythrocytes of animals in the effluent group and in the positive control group after 35 and 90 exposure days. Thus, the current study corroborated the hypothesis that the tannery effluent has aneugenic and clastogenic potential in adult male bullfrogs (L. castesbeianus). The present study is the first to report such effect.

Mice exposure to tannery effluents changes their olfactory capacity, and their response to predators and to the inhibitory avoidance test

The current study has assessed whether the oral and/or dermal exposure of C57Bl/6 J mice to tannery effluent (a complex pollutant consisting of xenobiotic mixtures) could damage their olfactory functions, as well as whether it changes their aversive behavior in the inhibitory avoidance test. Accordingly, the animals were distributed in groups which were exposed or not to this xenobiotic through two different routes (oral and dermal), for 15 days. The effluent group subjected to oral exposure received drinking water containing 5% tannery effluent, whereas the animals in the dermal group were exposed to raw tannery effluent for 1 h/day. The animals dermally exposed to the tannery effluent (males and females) have shown the highest latency to find palatable food in the buried food test. The shortest time spent by the animals (orally or dermally) exposed to tannery effluent in the safety zone of the apparatus used in the predator exposure test, as well as the longest time spent by them in the aversive zone, have shown failures in their perception to the risk represented by the presence of the predator (cat). The passive avoidance test results have shown that the dermal exposure to tannery effluent led to partial memory deficit in male and female mice; therefore, the present study has confirmed the tannery effluent toxicity to mammals. Moreover, the present study was pioneer in demonstrating that the dermal exposure to this xenobiotic, even for a short period-of-time, can change the olfactory and cognitive functions of animals, as well as lead to harmful consequences to their health.

Effects of nicotine on zebrafish: A comparative response between a newly established gill cell line and whole gills

A novel cell line, Danio rerio gill (DrG), derived from the gill tissue of zebrafish, was established and characterized. The cells were able to grow at a wide range of temperatures from 25°C to 32°C in Leibovitz's L-15 medium. The DrG cell line consists of epithelial-like cells with a diameter of 18-22μm. The cell line was characterized by mitochondrial 12S rRNA gene. Acute toxicity tests were conducted on D. rerio by exposing them to nicotine for 96h under static conditions. In vitro cytotoxicity of nicotine was assessed in DrG cell line using multiple endpoints such as 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), Neutral Red assay, Alamar Blue assay and Coomassie Blue protein assay. Linear correlations between each in vitro cytotoxicity assay and the in vivo mortality data were highly significant. Nicotine induced intracellular reactive oxygen species generation in DrG cell line in a concentration dependent manner. DrG cell line and zebrafish exposed to nicotine significantly increased the elevation of lipid peroxidation (LPO) while depletion of reduced glutathione (GSH), manganese superoxide dismutase (MnSOD), catalase (CAT), glutathione S-transferase (GST) and glutathione peroxidise(GPx1a) was observed. In nicotine treated fish and cells a negative correlation between reduced glutathione and LPO was observed. In addition, the production of ROS and the resulting oxidative stress resulted in increased expression of apoptosis related genes p53 and cas3.Collectively, our result suggests that nicotine has the potential to induce reactive oxygen species (ROS) production, oxidative stress and apoptosis in DrG cell line and zebrafish.

A pioneering study on cytotoxicity in Australian parakeets (Melopsittacus undulates) exposed to tannery effluent

Waste effluent from the tannery industry is a major source of environmental pollution. Considering that the bird intake of water contaminated with tannery effluent constitutes a potential genotoxic source, especially for birds inhabiting areas closest to tanning industries, the aim of this study is to assess the possible mutagenic effects that the intake may have on Melopsittacus undulatus (Australian parakeet). In order to do so, adult male and female M. undulatus were distributed in two experimental groups: control (drinking water) and TE (5%). After 60 days of exposure, the micronucleus test, as well as tests looking for other nuclear abnormalities in the peripheral blood of the birds were performed. The male and female birds exposed to the pollutant have presented the highest total number of nuclear abnormalities, as well as increased individual abnormalities such as nuclei with symmetrical constricted bi-lobed/bi-nucleated erythrocytes, indented nuclei and micro-lobed nuclei (top)/micro-nuclei (bottom). In addition, the exposure to TE has caused a nuclear variant increase rarely reported in the literature concerning poultry erythrocyte nuclei. The birds exposed to the pollutant have presented the highest frequency of displaced nuclei forming different rotation/displacement angles within the cells. Therefore, the current study confirmed the toxicological potential of TE and was pioneer in showing that male and female M. undulatus exposed to pollutant present the highest frequency of erythrocyte nuclear abnormalities, thus corroborating the initial hypothesis herein presented.

Inbred mice strain shows neurobehavioral changes when exposed to tannery effluent

The bovine leather processing (tanning industries) stands as a generating activity of potentially toxic waste. The emission of untreated effluents into the environment may cause serious harm to human and environmental health. Nevertheless, few studies have investigated the possible effects of intake of these effluents in experimental mammalian models. Thus, this study aimed to evaluate the neurobehavioral effects of chronic intake of different tannery effluent concentrations diluted with water (0.1, 1, and 5%) in male C57BL/6J mice. After 120 days of exposure, the animals were subjected to different behavioral tests, predictive of anxiety (elevated plus maze (EPM), open-field (OF), and neophobia test), depression (forced swim), and memory deficits (object recognition test). From the EPM test, it was observed that the mice exposed to 0.1, 1, and 5% of tannery effluents showed higher anxiety scores compared to the animals in the control group. However, the results of this study revealed no differences among the experimental groups in the proportion (percentage) of locomotion in the central quarters/total locomotion calculated (by OF), considered an indirect measure for anxiety. At neophobia test, all the animals exposed to chronic intake of tannery effluents showed higher latency time to start eating, which corresponds to an anxiogenic behavior. Regarding the forced swim test, it was observed that the animals exposed to tannery effluents had longer time in immobility behavior, suggesting a predictive behavior to depression. Finally, the object recognition test showed that the treatments did not cause damage to the animals' memory. The recognition rate of the new object did not differ among the experimental groups. Thus, it is concluded that male C57BL/6J mice (inbred strain) exposed to tannery effluents have predictive neurobehavioral changes of anxiety and depression, without memory deficit.

Microscale In Vitro Assays for the Investigation of Neutral Red Retention and Ethoxyresorufin-O-Deethylase of Biofuels and Fossil Fuels

Only few information on the potential toxic effectiveness of biofuels are available. Due to increasing worldwide demand for energy and fuels during the past decades, biofuels are considered as a promising alternative for fossil fuels in the transport sector. Hence, more information on their hazard potentials are required to understand the toxicological impact of biofuels on the environment. In the German Cluster of Excellence "Tailor-made Fuels from Biomass" design processes for economical, sustainable and environmentally friendly biofuels are investigated. In an unique and interdisciplinary approach, ecotoxicological methods are applied to gain information on potential adverse environmental effects of biofuels at an early phase of their development. In the present study, three potential biofuels, ethyl levulinate, 2-methyltetrahydrofuran and 2-methylfuran were tested. Furthermore, we investigated a fossil gasoline fuel, a fossil diesel fuel and an established biodiesel. Two in vitro bioassays, one for assessing cytotoxicity and one for aryl hydrocarbon receptor agonism, so called dioxin-like activity, as measured by Ethoxyresorufin-O-Deethylase, were applied using the permanent fish liver cell line RTL-W1 (Oncorhynchus mykiss). The special properties of these fuel samples required modifications of the test design. Points that had to be addressed were high substance volatility, material compatibility and low solubility. For testing of gasoline, diesel and biodiesel, water accommodated fractions and a passive dosing approach were tested to address the high hydrophobicity and low solubility of these complex mixtures. Further work has to focus on an improvement of the chemical analyses of the fuel samples to allow a better comparison of any effects of fossil fuels and biofuels.

Early Genotoxic and Cytotoxic Effects of the Toxic Dinoflagellate Prorocentrum lima in the Mussel Mytilus galloprovincialis

Okadaic acid (OA) and dinophysistoxins (DTXs) are the main toxins responsible for diarrhetic shellfish poisoning (DSP) intoxications during harmful algal blooms (HABs). Although the genotoxic and cytotoxic responses to OA have been evaluated in vitro, the in vivo effects of these toxins have not yet been fully explored. The present work fills this gap by evaluating the in vivo effects of the exposure to the DSP-toxin-producing dinoflagellate Prorocentrum lima during the simulation of an early HAB episode in the mussel Mytilus galloprovincialis. The obtained results revealed that in vivo exposure to this toxic microalgae induced early genotoxicity in hemocytes, as a consequence of oxidative DNA damage. In addition, the DNA damage observed in gill cells seems to be mainly influenced by exposure time and P. lima concentration, similarly to the case of the oxidative damage found in hemocytes exposed in vitro to OA. In both cell types, the absence of DNA damage at low toxin concentrations is consistent with the notion suggesting that this level of toxicity does not disturb the antioxidant balance. Lastly, in vivo exposure to growing P. lima cell densities increased apoptosis but not necrosis, probably due to the presence of a high number of protein apoptosis inhibitors in molluscs. Overall, this work sheds light into the in vivo genotoxic and cytotoxic effects of P. lima. In doing so, it also demonstrates for the first time the potential of the modified (OGG1) comet assay for assessing oxidative DNA damage caused by marine toxins in marine invertebrates.

Cardiomyocyte H9c2 cells present a valuable alternative to fish lethal testing for azoxystrobin

The present study aims at identifying, among six mammalian and fish cell lines, a sensitive cell line whose in vitro median inhibitory concentration (IC50) better matches the in vivo short-term Sparus aurata median lethal concentration (LC50). IC50s and LC50 were assessed after exposure to the widely used fungicide azoxystrobin (AZX). Statistical results were relevant for most cell lines after 48 h of AZX exposure, being H9c2 the most sensitive cells, as well as the ones which provided the best prediction of fish toxicity, with a LC50,96h/IC50,48h = 0.581. H9c2 cell proliferation upon 72 h of AZX exposure revealed a LC50,96h/IC50,72h = 0.998. Therefore, identical absolute sensitivities were attained for both in vitro and in vivo assays. To conclude, the H9c2 cell-based assay is reliable and represents a suitable ethical alternative to conventional fish assays for AZX, and could be used to get valuable insights into the toxic effects of other pesticides.

Development and use of retinal pigmented epithelial cell line from zebrafish (Danio rerio) for evaluating the toxicity of ultraviolet-B

Danio rerio retinal pigmented epithelial (DrRPE) cell line, derived from the RPE tissue, was established and characterized. The cells were able to grow at a wide range of temperatures from 25°C to 32°C in Leibovitz's L-15 medium. The DrRPE cell line consists of epithelial cells with a diameter of 15-19 μm. The cell line was characterized by mitochondrial 12S rRNA gene, immunocytochemical analysis, and karyotyping. DrRPE cells treated with 10 μM of all-trans-retinol for 24 h readily formed lipid droplets. DrRPE cells were irradiated with narrowband ultraviolet-B (UV-B) radiation at different time periods of 0, 10, 20, and 40 min. The cells were subsequently examined for changes in morphology, cell viability, phagocytotic activity, mitochondrial distribution, nuclei morphology, generation of reactive oxygen species, and expression of apoptotic-related genes p53 and Cas3 by quantitative polymerase chain reaction. The results demonstrate that UV-B radiation can cause a considerable decrease in DrRPE cell viability as well as in phagocytotic activity. In addition, the results demonstrate that UV-B radiation can induce the degradation of mitochondria and DNA in cultured DrRPE cells.

Cytotoxicity, genotoxicity and oxidative stress of malachite green on the kidney and gill cell lines of freshwater air breathing fish Channa striata

The cytotoxicity, genotoxicity and oxidative stress of malachite green (MG) was investigated using the fish Channa striata kidney (CSK) and Channa striata gill (CSG) cell lines. Five concentrations ranging from 0.001 to 10 μg mL(-1) were tested in three independent experiments. Cytotoxicity was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, Rhodamine 123 and Alamar Blue. The mitochondrial changes and apoptosis of MG-exposed cells were observed by Rhodamine 123 and acridine orange/ethidium bromide (AO/EB) staining, respectively. In vitro potential DNA damaging effect of MG was tested using comet assay. Mitochondrial damage, apoptosis and DNA fragmentation increased in a concentration-dependent manner. Additionally, DNA electrophoretic mobility experiments were carried out to study the binding effect of MG to double-stranded DNA (dsDNA) of cells. DNA shift mobility experiments showed that MG is capable of strongly binding to linear dsDNA causing its degradation. Biochemical parameters such as lipid peroxidation (MDA), catalase (CAT) activity and reduced glutathione (GSH) levels were evaluated after exposure to MG. In CSK and CSG cell lines exposed to MG for 48 h, a significant increase in lipid peroxidation, which might be associated with decreased levels of reduced glutathione and catalase activity in these cell lines (p < 0.001), was observed.

In vitro cytotoxic, genotoxic and oxidative stress of cypermethrin on five fish cell lines

The indiscriminate use of pesticides and herbicides to enhance crop production has aroused great concern, because these products are likely to reach the aquatic environment, thereby posing a health concern for humans and aquatic species. Cypermethrin (CYP), a type II pyrethroid insecticide, is widely used in agriculture and for other purposes. Therefore a study was conducted for the assessment of cytotoxic, genotoxic and oxidative stress of CYP in IEG, CB, ICG, LRG and CSG cell lines at 24h exposure. The cytotoxic effect of CYP in IEG, CB, ICG, LRG and CSG cell lines was assessed using MTT, NR, AB and CB assays. Linear correlations between each EC50 values, of CYP resulting in 50% inhibition of cytotoxicity parameters after 24h exposure to CYP were calculated for IEG, CB, ICG, LRG and CSG cell lines using MTT, NR, AB and CB assays. Statistical analysis revealed good correlation with R(2)=0.90-0.939 for all combinations between endpoints employed. The percentage of DNA damage was assessed by comet assay in IEG, CB, ICG, LRG and CSG cells exposed to CYP. The results of antioxidant parameters obtained show a significant increase in lipid peroxidation (LPO) level and decreased level of GSH, SOD and CAT in IEG, CB, ICG, LRG and CSG cell lines after exposure to increasing CYP in a concentration-dependent manner. This work proves that fish cell lines could be used not only for cytotoxicity and genotoxicity studies but also for studying oxidative stress when exposed to environmental contaminants such as pesticides and other pollutants.

In vitro assay for the toxicity of silver nanoparticles using heart and gill cell lines of Catla catla and gill cell line of Labeo rohita

Silver nanoparticles (Ag-NPs) are used in commercial products for their antimicrobial properties. The Ag-NPs in some of these products are likely to reach the aquatic environment, thereby posing a health concern for humans and aquatic species. The silver nanoparticles were synthesized and characterized using, UV-vis spectra, Dynamic light scattering (DLS) and Transmission electron microscopy (TEM) analysis. Acute toxicity tests on fish were conducted by exposing Catla catla and Labeo rohita for 96h to AgNO3 and Ag-NPs under static conditions. The cytotoxic effect of AgNO3 and Ag-NPs in Sahul India C. catla heart cell line (SICH), Indian C. catla gill cell line (ICG) and L. rohita gill cell line (LRG) was assessed using MTT and neutral red (NR) assay. Linear correlations between each in vitro EC50 and the in vivo LC50 data were highly significant. DNA damage and nuclear fragmentation (condensation) were assessed by comet assay and Hoechst staining, respectively in SICH, ICG and LRG cells exposed to Ag-NPs. The results of antioxidant parameter obtained show significantly increased lipid peroxidation (LPO) level and decreased level of GSH, SOD and CAT in SICH, ICG and LRG cell lines after exposure to increasing Ag-NPs in a concentration-dependent manner. This work proves that fish cell lines could be used as an alternative to whole animals using cytotoxicity tests, genotoxicity tests and oxidative stress assessment after exposure to nanoparticles.

Development and characterization of a new gill cell line from air breathing fish Channa striatus (Bloch 1793) and its application in toxicology: direct comparison to the acute fish toxicity

A new cell line, Channa striatus gill (CSG), derived from the gill tissue of murrel, was established and characterized. The CSG cell line was maintained in Leibovitz's L-15 supplemented with 10% fetal bovine serum and has been subcultured more than 92 times. This cell line was able to grow in a range of temperatures from 22 to 32°C with optimal growth at 28°C. The plating efficiency was very high (52.21%) and doubling time was approximately 37h. The gill cell line was cryopreserved at different passage levels and revived successfully with 85% survival. Polymerase chain reaction amplification of mitochondrial 16S rRNA using primer specific to C. striatus confirmed the origin of this cell line from murrel. The cell line was further characterized by immunocytochemical analysis, chromosome number, transfection and mycoplasma detection. The cytotoxicity of endosulfan was assessed in CSG cell line using apoptosis assay, comet assay, mitochondrial alteration and five other endpoints such as Rhodamine 123 uptake, 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, neutral red assay, Alamar Blue assay and Methylene Blue protein assay. Acute toxicity study on fish was conducted by exposing murrel for 96h to endosulfan under static conditions. Statistical analysis revealed good correlation with r(2)=0.972-0.997 among the five endpoints. Linear correlations between the in vivo lethal concentration 50 (LC50) and each in vitro effective concentration 50 (EC50) were highly significant. The present study highlights the development of a new gill cell line from an air breathing fish that could be used as an alternative in vitro tools for studying pesticide toxicity in fish.

Development, characterization and application of a new fibroblastic-like cell line from kidney of a freshwater air breathing fish Channa striatus (Bloch, 1793)

A new cell line, Channa striatus kidney (CSK), derived from the kidney tissue of murrel, was established and characterized. The CSK cell line was maintained in Leibovitz's L-15 supplemented with 10% fetal bovine serum and has been subcultured more than 140 times. This cell line was able to grow in a range of temperatures from 22 to 32°C with optimal growth at 28°C. The plating efficiency was very high (67.54%) and doubling time was approximately 29h. The kidney cell line was cryopreserved at different passage levels and revived successfully with 90-92% survival. Polymerase chain reaction amplification of mitochondrial 16S rRNA using primer specific to C. striatus confirmed the origin of this cell line from murrel. The cell line was further characterized by chromosome number, transfection and mycoplasma detection. A marine fish nodavirus was tested to determine the susceptibility of this new cell line. The CSK cell line was found to be susceptible to nodavirus and the infection was confirmed by cytopathic effect (CPE), reverse transcriptase-polymerase chain reaction (RT-PCR), immunodot blot, enzyme linked immunosorbent assay (ELISA), virus replication efficiency and real time RT-PCR. The present study highlights the development and characterization of a new kidney cell line from an air breathing fish that could be used as an in vitro tools for propagation of fish viruses and gene expression studies.

PKH26 can transfer to host cells in vitro and vivo

The fluorescent dye, PKH26, which mainly binds to the cell membrane, has been used as the cell tracer to locate the transplanted cells in host for a long time. However, there was no detailed report that whether the PKH26 dye was specific to the transplanted cells. Therefore, the aim of this article is to explore the effect of cells debris as the cracking cells from the PKH26-labeled adipose-derived stem cells (ADSCs) on the cells in vitro and the host in vivo. After we tested the proliferation and toxicity of PKH26 to the ADSCs by the Cell Count-8 kit and alamar blue assay, we constructed 2 models, coculturing lots of PKH26-labeled cell debris with the unlabeled ADSCs in vitro and injecting via the tail vein in rat, to evaluate the specificity of the PKH26 dye. The result indicated that the PKH26 didn't inhibit the proliferation and had no toxicity to the ADSCs compared with the unlabeled ADSCs, but the cell debris cracking from PKH26-labeled transplanted cells can cause the unlabeled cells to emit red fluorescence in vitro and also lead the tissues displaying red fluorescence in vivo. We can conclude that the PKH26 dye, used as a cell tracer for a long time, was not an ideal cell tracer.