José Navas - Academia.edu (original) (raw)

Papers by José Navas

Aquatic Toxicology, 2013

Please cite this article as: Quesada-García, A., Valdehita, A., Torrent, F., Villarroel, M., Hern... more Please cite this article as: Quesada-García, A., Valdehita, A., Torrent, F., Villarroel, M., Hernando, M.D., Navas, J.M., Use of fish farms to assess river contamination: combining biomarker responses, active biomonitoring, and chemical analysis., Aquatic Toxicology (2013), http://dx.

Aquatic toxicology (Amsterdam, Netherlands), Jan 13, 2009

A combination of cost effective sublethal Daphnia magna feeding tests, yeast- and cell culture-ba... more A combination of cost effective sublethal Daphnia magna feeding tests, yeast- and cell culture-based bioassays and Toxicity Identification Evaluation (TIE) procedures was used to characterize toxic compounds within sediments collected in a river area under the influence of the effluents from a chlor-alkali industry (Ebro River, NE Spain). Tests were designed to measure and identify toxic compounds in the particulate and filtered water fractions of sediment elutriates. The combined use of bioassays responding to elutriates and dioxin-like compounds evidenced the existence of three major groups of hazardous contaminants in the most contaminated site: (A) metals such as cadmium and mercury bound to sediment fine particles that could be easily resuspended and moved downstream, (B) soluble compounds (presumably, lye) able to alkalinize water to toxic levels, and (C) organochlorine compounds with high dioxin-like activity. These results provided evidence that elutriate D. magna feeding re...

Environmental toxicology and chemistry / SETAC, 2006

It has been accepted that aryl hydrocarbon receptor (AhR) ligands are compounds with two or more ... more It has been accepted that aryl hydrocarbon receptor (AhR) ligands are compounds with two or more aromatic rings in a coplanar conformation. Although general agreement exists that carbaryl is able to activate the AhR, it has been proposed that such activation could occur through alternative pathways without ligand binding. This idea was supported by studies showing a planar conformation of carbaryl as unlikely. The objective of the present work was to clarify the process of AhR activation by carbaryl. In rat H4IIE cells permanently transfected with a luciferase gene under the indirect control of AhR, incubation with carbaryl led to an increase of luminescence. Ligand binding to the AhR was studied by means of a cell-free in vitro system in which the activation of AhR can occur only by ligand binding. In this system, exposure to carbaryl also led to activation of AhR. These results were similar to those obtained with the AhR model ligand beta-naphthoflavone, although this compound exh...

Alternatives to laboratory animals : ATLA, 2014

Atrazine, prometryn, propazine and simazine are chlorotriazines that are commonly employed as her... more Atrazine, prometryn, propazine and simazine are chlorotriazines that are commonly employed as herbicides. However, their use is a major cause of concern, due to their reported endocrine disrupting effects in different taxa. Data from studies on the molecular and cellular processes underlying the hormonal action of these substances are contradictory. The ability of these chlorotriazines and the atrazine metabolites, desethyl-s-chlorotriazine and desisopropyl-s-chlorotriazine, to trigger responses mediated by the oestrogen receptor (ER), aryl hydrocarbon receptor (AhR) and thyroid receptor (TR), was studied by using in vitro approaches. Transcriptional activation assays were applied to observe the activation of ER and TR. The induction of ethoxyresorufin-O-deethylase (EROD) activity in the RTG-2 cell line served as an indicator of AhR activation. No responses were found in any of the assays, with any of the six chlorotriazines tested. Our observations indicate that the chlorotriazines...

Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 2015

Aflatoxin B1 (AFB1) and fumonisin B1 (FB1) are mycotoxins widely found as cereal contaminants and... more Aflatoxin B1 (AFB1) and fumonisin B1 (FB1) are mycotoxins widely found as cereal contaminants and their co-occurrence in corn has been associated with a high incidence of liver cancer. Both toxins are immunotoxic, with AFB1 being a procarcinogen, and its bioactivation through specific cytochrome P450 (Cyp) enzymes, such as Cyp1A, being a requirement for hepatocarcinogenic and toxic activities. This study evaluated the effects of these mycotoxins, alone or combined, on activation and expression of Cyp1A and its transcription factor aryl hydrocarbon receptor (Ahr) in hepatoma cell line H4IIE and spleen mononuclear cells of rats. The results demonstrate that in H4IIE cells, AFB1 induced an increase in Cyp1A activity and cyp1A transcription, associated with an enhanced Ahr activity, which suggests that this toxin can act as an Ahr agonist. Moreover, FB1 caused a small rise in Cyp1A activity and cyp1A expression. Similarly in spleen cells, AFB1 and FB1 induced overexpression of cyp1A and...

Bioorganic & Medicinal Chemistry Letters, 2004

With the objective to understand structural features responsible for the biological activity, nov... more With the objective to understand structural features responsible for the biological activity, novel nonelectrophilic biphenyl derivatives and peptide-biphenyl hybrids have been synthesized and evaluated as calpain I inhibitors. The preliminary results indicate that the presence of additional aromatic rings (besides the biphenyl system) makes these compounds potent calpain inhibitors with IC50 values in the nanomolar range.

Archives of environmental contamination and toxicology, Jan 13, 2015

Aquatic organisms are often exposed to mixtures of low levels of pollutants whose presence and ef... more Aquatic organisms are often exposed to mixtures of low levels of pollutants whose presence and effects can pass easily unnoticed if only traditional monitoring strategies are employed. The main aim of this work was to assess the presence and effects of trace levels of pollutants in a scarcely affected area through the combination of chemical and biological approaches. Sediments were collected along a river with little anthropogenic pressure and assayed for cytochrome P450 (Cyp1a)-dependent ethoxyresorufin-O-deethylase (EROD) activity with the rainbow trout gonadal cell line RTG-2. Chemical analyses were performed in these sediments using two-dimensional gas chromatography-time-of-flight mass spectrometry. Sediment samples induced EROD activity, and chemical analyses evidenced the presence of a wide variety of contaminants in the range of nanograms per gram of dry weight. Correlation analysis between EROD induction and chemical analyses data showed an r value of 0.840 (p < 0.05). ...

Toxicology in Vitro, 2005

A variety of aquatic pollutants are able to induce cytochrome P4501A (CYP1A) in fish by ligand bi... more A variety of aquatic pollutants are able to induce cytochrome P4501A (CYP1A) in fish by ligand binding to the aryl hydrocarbon receptor (AhR). High-affinity AhR ligands are planar aromatic polycyclic molecules such as the prototypical ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The present work investigates the ability of the imidazole derivative, Prochloraz (PRO), to induce CYP1A. Computational studies on the molecular structure of

Alternatives to laboratory animals : ATLA, 2014

Talanta, 2012

This work focuses on a revision of analytical methodologies for the determination of industrial c... more This work focuses on a revision of analytical methodologies for the determination of industrial chemicals that have an endocrine-disrupting effect on food commodities. These food commodities have been divided into two major categories: crops and food of animal origin. The reviewed methods have been commented on in terms of sample preparation, analytical methods, and the occurrence of the studied compounds.

Nanotoxicology, 2013

The progressive practical applications of engineered nanoparticles results in their ever-increasi... more The progressive practical applications of engineered nanoparticles results in their ever-increasing release into the environment. Accurate assessment of their environmental and health risks requires the development of methods allowing their monitoring in different environmental compartments and the evaluation of their potential toxicity at different levels of organization. Toxic effects of third-generation (G3) and fourth-generation (G4) poly(amidoamine) dendrimers (ethylenediamine cored, imine-terminated) were assessed on zebrafish embryos during the first two days post-fertilization. Particle characterization by dynamic light scattering showed no tendency to form aggregates in the assay conditions. G3 particles showed somewhat a higher acute toxicity than G4 particles, with LC50 values of 1.8 and 2.3 mg/L, respectively. At sublethal concentrations, both particles affected the zebrafish transcriptome following similar patterns, suggesting a similar mode of action. About 700 transcripts were affected by at least one of the treatments, following a pattern with significant correlations to the effects of bacterial infection in zebrafish embryos. We concluded that the response to G3 and G4 dendrimers was consistent with the activation of the innate immune response, a still unreported potential effect of these particles. These data may contribute to the characterization of hazards of these nanomaterials for both human health and the environment.

Fish & Shellfish Immunology, 2014

Thyroid hormones are involved in modulating the immune system in mammals. In contrast, 17 there i... more Thyroid hormones are involved in modulating the immune system in mammals. In contrast, 17 there is no information on the role played by these hormones in the immune system of teleost 18 fish. Here we provide initial evidence for the presence of active thyroid signaling in immune 19 organs and cells of teleosts. We demonstrate that immune organs (head kidney and spleen) 20 and isolated leukocytes (from head kidney and peripheral blood) of the rainbow trout 21 (Oncorhynchus mykiss) express both thyroid receptor α (THRA) and β (THRB). Absolute 22 mRNA levels of THRA were significantly higher than those of THRB. THRA showed higher 23 expression in immune organs and isolated immune cells compared to the reference organ, 24 liver, while THRB showed the opposite. In vivo exposure of trout to triiodothryronine (T3) or 25 the anti-thyroid agent propylthiouracil (PTU) altered THR expression in immune organs and 26 cells. 27 Effect of T3 and PTU over the relative expression of selected marker genes of immune cell 28 subpopulations was also studied. Treatments changed the relative expression of markers of 29 cytotoxic, helper and total T cells (cd4, cd8a, trb), B lymphocytes (mIgM) and macrophages 30 (csf1r). These findings suggest that the immune system of rainbow trout is responsive to 31 thyroid hormones. 32 33 34

Environmental Toxicology and Chemistry, 2003

Xenobiotics can induce cytochrome P4501A (CYP1A) by ligand binding to the aryl hydrocarbon recept... more Xenobiotics can induce cytochrome P4501A (CYP1A) by ligand binding to the aryl hydrocarbon receptor (AhR). Typical AhR ligands are polycyclic aromatic compounds with planar molecular conformation. The present work investigated the ability of the N-imidazole derivative, 1-benzylimidazole (BIM), to induce CYP1A in rainbow trout hepatocytes. Benzylimidazole increased hepatocellular CYP1A catalytic activity (determined as 7-ethoxyresorufin-O-deethylase [EROD] activity) and CYP1A mRNA in a concentration-dependent way. Computational studies on the molecular structure of BIM indicated that the energetically most stable BIM conformer has the imidazole ring and the phenyl ring in different planes, i.e., does not take a planar conformation. This property of BIM does not agree with the structural requirements of a typical AhR ligand. In line with this observation, we found that the AhR antagonist, ␣-naphthoflavone (␣NF), was not able to inhibit BIM induction of EROD activity and CYP1A mRNA, although it inhibited the induction of CYP1A by the prototypic AhR ligand, ␤-naphthoflavone (␤NF). The results suggest that transcriptional activation of CYP1A by the N-imidazole derivative, BIM, is not mediated through direct ligand binding to the AhR.

Environmental Science and Pollution Research, 1998

A number of natural and man-made chemicals possess antiestrogenic activity, i.e. they antagonize ... more A number of natural and man-made chemicals possess antiestrogenic activity, i.e. they antagonize a broad spectrum of estrogeninduced responses in vertebrates. Examples of antiestrogens include dioxin, furan and PCB congeners, certain PAHs, pesticides and indol-3-carbinol derivatives. Major mechanisms of antiestrogenicity are antagonistic action of chemicals at the estrogen receptor, or binding of chemicals to the arylhydrocarbon (Ah) receptor and subsequent interaction with estrogen-responsive genes. Toxicological consequences resulting from antiestrogenic activity have not been conclusively demonstrated to date, although antiestrogenic compounds could critically affect sensitive reproductive and developmental processes. Abbreviations : AhR = arylhydrocarbon receptor, E2 = 17Gestradiol, X = xenobiotic, E2R = estrogen receptor, ERE = estrogen responsive element on the DNA, P450 = cytochrome P450 gene or enzyme, XRE = xenobiotic (or dioxin) responsive element on the DNA

Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2012

In order to study the variability of detoxification activities associated with the cytochromes P4... more In order to study the variability of detoxification activities associated with the cytochromes P450 1A (CYP1A) and 3A (CYP3A), several continental fish farms of Oncorhynchus mykiss were routinely sampled. In fish, CYP1A plays a key role in the biotransformation of a wide variety of pollutants. This cytochrome is induced after ligand-activation of the aryl hydrocarbon receptor. CYP3A is also implicated in the metabolism of a wide variety of xenobiotics, including pharmaceuticals however its activity is mediated by the pregnane-X-receptor. CYP1A and CYP3A inductions have been widely used as biomarkers of environmental pollution in aquatic systems, in particular when measured at the enzymatic level through ethoxyresorufin-O-deethylase (EROD) and benzyloxy-4-[trifluoromethyl]-coumarin-O-debenzyloxylase (BFCOD) activities, respectively. In one of the monitored fish farms, EROD activity, which initially showed basal levels, exhibited a sharp increase difficult to explain by seasonal variability. In order to confirm the increased induction of the cytochrome activities, 32 animals were transferred to a control farm and maintained for one month. Periodic samplings of eight animals at days 0, 7, 15 and 30 were performed and both EROD and BFCOD activities in the livers measured. Under these controlled conditions, enzymatic activities associated with detoxification processes gradually decreased to basal levels indicating the presence of some factor in the fish farm inducing the cytochromes. In order to investigate possible causes of such induction both water and sediment samples, along the river feeding the fish farm, were taken and analysed by a GCxGC-TOFMS system. This system proved very useful and allowed us to identify non-target compounds in some samples, among them personal care, pharmaceutical products, and industrial chemicals (i.e. PAHs, phthalates, alkylphenolic compounds) that could be related to the observed induction.

Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2012

The widely used herbicide atrazine (ATZ) has been reported to exhibit reproductive toxicity in ra... more The widely used herbicide atrazine (ATZ) has been reported to exhibit reproductive toxicity in rats, fish and amphibians, with an avian LD(50) of 5000 mg/kg. In the present work, ATZ was administered as a single oral dose of 25 or 100 mg/kg to female European quail (Coturnix coturnix coturnix) at days 0, 5 and 10 of the experiment, being the animals sampled at days 15, 30 and 45. ATZ significantly increased the expression of hepatic estrogen receptor α (ERα) at both doses at day 30. An important increase was also observed in plasma 17β-estradiol (E2) concentrations. ATZ at 100 mg/kg increased the circulating concentration of vitellogenin (Vtg), but this effect was not related with an increase in hepatic Vtg mRNA levels. ATZ had no effect on the hepatic expression of both cytochrome P450 1A4 (CYP1A4) or the related biotransformation activity ethoxyresorufin-O-deethylase (EROD). These results led to the conclusion that ATZ provokes an estrogenic effect in sexually mature females of European quail. Further studies are necessary to establish the effect on sexual development or reproduction of female and male birds in the wild.

Chemico-Biological Interactions, 2001

Hepatic CYP1A expression in fish can be modulated by the female sex hormone, 17beta-estradiol (E2... more Hepatic CYP1A expression in fish can be modulated by the female sex hormone, 17beta-estradiol (E2), however neither the mechanism of E2 suppression of CYP1A nor the capacity for hormonal regulation to overcome CYP1A induction by xenobiotics are known. The present study investigates for the first time in fish if the estrogen receptor (ER) is involved in the suppressive action of E2 on CYP1A gene expression. The study further examines, if the E2 effect is able to overcome xenobiotic induction of CYP1A. As experimental model, in vitro cultures of rainbow trout, Oncorhynchus mykiss, hepatocytes were used. The effect of E2 on CYP1A was assessed by measuring the CYP1A-associated 7-ethoxyresorufin-O-deethylase (EROD) enzyme activity, and CYP1A mRNA contents. E2 at non-cytotoxic concentrations caused a significant time- and concentration-dependent decline of basal but not of induced hepatic EROD activities. The inhibitory action of E2 on basal CYP1A was also evident at the mRNA level. The presence of the ER antagonist tamoxifen abolished the inhibitory action of E2 on CYP1A expression. The results from these in vitro experiments provide evidence (a) that the ER is involved in the suppressive action of E2 on CYP1A, and (b) that E2 inhibitory action does not overcome xenobiotic induction of CYP1A.

Archives of Environmental Contamination and Toxicology, 2013

The effect of orally administered atrazine (25 or 100 mg/kg on days 0, 5, and 10 of the experimen... more The effect of orally administered atrazine (25 or 100 mg/kg on days 0, 5, and 10 of the experiment) was studied in European quail (Coturnix coturnix coturnix) on four non-destructive biomarkers: fecal porphyrins, blood glutathione-S-transferase, glutathione reductase, reduced glutathione, and malondialdehyde (MDA). Uroporphyrin I (UPI) and coproporphyrins I and III (CPIII) were the main porphyrins detected in feces. The lowest dose of ATZ caused a significant (P &amp;amp;amp;amp;lt; 0.05) increase in UPI and CPIII at day 5, and the highest dose of ATZ caused an induction of CPI and a significant (P &amp;amp;amp;amp;lt; 0.05) decrease in MDA levels at day 30.

Aquatic Toxicology, 2000

The aims of the present study were to assess, (1) if polyaromatic hydrocarbons (PAHs) are able to... more The aims of the present study were to assess, (1) if polyaromatic hydrocarbons (PAHs) are able to inhibit estradiol-regulated vitellogenin synthesis in fish; and (2) if this antiestrogenic activity is mediated through the binding of PAHs to the arylhydrocarbon receptor (AhR). Cultured liver cells of rainbow trout, Oncorhynchus mykiss, were co-exposed to PAHs and 17β-estradiol (E2), and the resulting effects

Aquatic Toxicology, 2008

Polycyclic aromatic hydrocarbons (PAHs) are assumed to be the primary determinant of oil petroleu... more Polycyclic aromatic hydrocarbons (PAHs) are assumed to be the primary determinant of oil petroleum toxicity. Since the PAH content in Prestige oil was relatively high, we investigated the effects of different oil fractions (crude or weathered oil −0.05 to 50 g/L, and shaken or sonicated water accommodated fractions, WAFs, 25-100%, v/v) on the embryo-larval development of medaka (Oryzias latipes). Concentrations of 16PAHs analyzed in the incubation medium were highest in the shaken WAF followed by the crude oil, the sonicated WAF and the weathered oil. Both oils (≥0.25 g/L) induced developmental abnormalities whereas no significant effects were seen in the WAF exposures. In vivo morphometric analysis of the surface of the gallbladder during advanced embryo organogenesis (192 h post-fertilization, hpf) revealed significant dilation in both WAF exposures (>3 × 10 4 m 2 at ≥25%, v/v, compared to <1.7 × 10 4 m 2 at 0%, v/v) followed by the crude oil (>2.2 × 10 4 m 2 at ≥0.05 g/L). Fluorescent aromatic compounds were observed in the gallbladder and the yolk sac of 168-hpf embryos exposed to all oil fractions. Results suggest the presence of components in both oils capable of penetrating the chorion and inducing a toxicity not observed in the WAFs. Hence, the hazard and risk assessment of Prestige oil should not be based solely on the presence of PAHs since proximity or direct contact may induce toxicity not associated exclusively to these compounds. This research offers a new hypothesis for explaining the reported biological observations, which could be correlated to direct oil exposure rather than the traditional mechanism of waterborne PAH exposure. Further research is needed to identify those oil components responsible for toxicity.

Aquatic Toxicology, 2013

Please cite this article as: Quesada-García, A., Valdehita, A., Torrent, F., Villarroel, M., Hern... more Please cite this article as: Quesada-García, A., Valdehita, A., Torrent, F., Villarroel, M., Hernando, M.D., Navas, J.M., Use of fish farms to assess river contamination: combining biomarker responses, active biomonitoring, and chemical analysis., Aquatic Toxicology (2013), http://dx.

Aquatic toxicology (Amsterdam, Netherlands), Jan 13, 2009

A combination of cost effective sublethal Daphnia magna feeding tests, yeast- and cell culture-ba... more A combination of cost effective sublethal Daphnia magna feeding tests, yeast- and cell culture-based bioassays and Toxicity Identification Evaluation (TIE) procedures was used to characterize toxic compounds within sediments collected in a river area under the influence of the effluents from a chlor-alkali industry (Ebro River, NE Spain). Tests were designed to measure and identify toxic compounds in the particulate and filtered water fractions of sediment elutriates. The combined use of bioassays responding to elutriates and dioxin-like compounds evidenced the existence of three major groups of hazardous contaminants in the most contaminated site: (A) metals such as cadmium and mercury bound to sediment fine particles that could be easily resuspended and moved downstream, (B) soluble compounds (presumably, lye) able to alkalinize water to toxic levels, and (C) organochlorine compounds with high dioxin-like activity. These results provided evidence that elutriate D. magna feeding re...

Environmental toxicology and chemistry / SETAC, 2006

It has been accepted that aryl hydrocarbon receptor (AhR) ligands are compounds with two or more ... more It has been accepted that aryl hydrocarbon receptor (AhR) ligands are compounds with two or more aromatic rings in a coplanar conformation. Although general agreement exists that carbaryl is able to activate the AhR, it has been proposed that such activation could occur through alternative pathways without ligand binding. This idea was supported by studies showing a planar conformation of carbaryl as unlikely. The objective of the present work was to clarify the process of AhR activation by carbaryl. In rat H4IIE cells permanently transfected with a luciferase gene under the indirect control of AhR, incubation with carbaryl led to an increase of luminescence. Ligand binding to the AhR was studied by means of a cell-free in vitro system in which the activation of AhR can occur only by ligand binding. In this system, exposure to carbaryl also led to activation of AhR. These results were similar to those obtained with the AhR model ligand beta-naphthoflavone, although this compound exh...

Alternatives to laboratory animals : ATLA, 2014

Atrazine, prometryn, propazine and simazine are chlorotriazines that are commonly employed as her... more Atrazine, prometryn, propazine and simazine are chlorotriazines that are commonly employed as herbicides. However, their use is a major cause of concern, due to their reported endocrine disrupting effects in different taxa. Data from studies on the molecular and cellular processes underlying the hormonal action of these substances are contradictory. The ability of these chlorotriazines and the atrazine metabolites, desethyl-s-chlorotriazine and desisopropyl-s-chlorotriazine, to trigger responses mediated by the oestrogen receptor (ER), aryl hydrocarbon receptor (AhR) and thyroid receptor (TR), was studied by using in vitro approaches. Transcriptional activation assays were applied to observe the activation of ER and TR. The induction of ethoxyresorufin-O-deethylase (EROD) activity in the RTG-2 cell line served as an indicator of AhR activation. No responses were found in any of the assays, with any of the six chlorotriazines tested. Our observations indicate that the chlorotriazines...

Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 2015

Aflatoxin B1 (AFB1) and fumonisin B1 (FB1) are mycotoxins widely found as cereal contaminants and... more Aflatoxin B1 (AFB1) and fumonisin B1 (FB1) are mycotoxins widely found as cereal contaminants and their co-occurrence in corn has been associated with a high incidence of liver cancer. Both toxins are immunotoxic, with AFB1 being a procarcinogen, and its bioactivation through specific cytochrome P450 (Cyp) enzymes, such as Cyp1A, being a requirement for hepatocarcinogenic and toxic activities. This study evaluated the effects of these mycotoxins, alone or combined, on activation and expression of Cyp1A and its transcription factor aryl hydrocarbon receptor (Ahr) in hepatoma cell line H4IIE and spleen mononuclear cells of rats. The results demonstrate that in H4IIE cells, AFB1 induced an increase in Cyp1A activity and cyp1A transcription, associated with an enhanced Ahr activity, which suggests that this toxin can act as an Ahr agonist. Moreover, FB1 caused a small rise in Cyp1A activity and cyp1A expression. Similarly in spleen cells, AFB1 and FB1 induced overexpression of cyp1A and...

Bioorganic & Medicinal Chemistry Letters, 2004

With the objective to understand structural features responsible for the biological activity, nov... more With the objective to understand structural features responsible for the biological activity, novel nonelectrophilic biphenyl derivatives and peptide-biphenyl hybrids have been synthesized and evaluated as calpain I inhibitors. The preliminary results indicate that the presence of additional aromatic rings (besides the biphenyl system) makes these compounds potent calpain inhibitors with IC50 values in the nanomolar range.

Archives of environmental contamination and toxicology, Jan 13, 2015

Aquatic organisms are often exposed to mixtures of low levels of pollutants whose presence and ef... more Aquatic organisms are often exposed to mixtures of low levels of pollutants whose presence and effects can pass easily unnoticed if only traditional monitoring strategies are employed. The main aim of this work was to assess the presence and effects of trace levels of pollutants in a scarcely affected area through the combination of chemical and biological approaches. Sediments were collected along a river with little anthropogenic pressure and assayed for cytochrome P450 (Cyp1a)-dependent ethoxyresorufin-O-deethylase (EROD) activity with the rainbow trout gonadal cell line RTG-2. Chemical analyses were performed in these sediments using two-dimensional gas chromatography-time-of-flight mass spectrometry. Sediment samples induced EROD activity, and chemical analyses evidenced the presence of a wide variety of contaminants in the range of nanograms per gram of dry weight. Correlation analysis between EROD induction and chemical analyses data showed an r value of 0.840 (p < 0.05). ...

Toxicology in Vitro, 2005

A variety of aquatic pollutants are able to induce cytochrome P4501A (CYP1A) in fish by ligand bi... more A variety of aquatic pollutants are able to induce cytochrome P4501A (CYP1A) in fish by ligand binding to the aryl hydrocarbon receptor (AhR). High-affinity AhR ligands are planar aromatic polycyclic molecules such as the prototypical ligand, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The present work investigates the ability of the imidazole derivative, Prochloraz (PRO), to induce CYP1A. Computational studies on the molecular structure of

Alternatives to laboratory animals : ATLA, 2014

Talanta, 2012

This work focuses on a revision of analytical methodologies for the determination of industrial c... more This work focuses on a revision of analytical methodologies for the determination of industrial chemicals that have an endocrine-disrupting effect on food commodities. These food commodities have been divided into two major categories: crops and food of animal origin. The reviewed methods have been commented on in terms of sample preparation, analytical methods, and the occurrence of the studied compounds.

Nanotoxicology, 2013

The progressive practical applications of engineered nanoparticles results in their ever-increasi... more The progressive practical applications of engineered nanoparticles results in their ever-increasing release into the environment. Accurate assessment of their environmental and health risks requires the development of methods allowing their monitoring in different environmental compartments and the evaluation of their potential toxicity at different levels of organization. Toxic effects of third-generation (G3) and fourth-generation (G4) poly(amidoamine) dendrimers (ethylenediamine cored, imine-terminated) were assessed on zebrafish embryos during the first two days post-fertilization. Particle characterization by dynamic light scattering showed no tendency to form aggregates in the assay conditions. G3 particles showed somewhat a higher acute toxicity than G4 particles, with LC50 values of 1.8 and 2.3 mg/L, respectively. At sublethal concentrations, both particles affected the zebrafish transcriptome following similar patterns, suggesting a similar mode of action. About 700 transcripts were affected by at least one of the treatments, following a pattern with significant correlations to the effects of bacterial infection in zebrafish embryos. We concluded that the response to G3 and G4 dendrimers was consistent with the activation of the innate immune response, a still unreported potential effect of these particles. These data may contribute to the characterization of hazards of these nanomaterials for both human health and the environment.

Fish & Shellfish Immunology, 2014

Thyroid hormones are involved in modulating the immune system in mammals. In contrast, 17 there i... more Thyroid hormones are involved in modulating the immune system in mammals. In contrast, 17 there is no information on the role played by these hormones in the immune system of teleost 18 fish. Here we provide initial evidence for the presence of active thyroid signaling in immune 19 organs and cells of teleosts. We demonstrate that immune organs (head kidney and spleen) 20 and isolated leukocytes (from head kidney and peripheral blood) of the rainbow trout 21 (Oncorhynchus mykiss) express both thyroid receptor α (THRA) and β (THRB). Absolute 22 mRNA levels of THRA were significantly higher than those of THRB. THRA showed higher 23 expression in immune organs and isolated immune cells compared to the reference organ, 24 liver, while THRB showed the opposite. In vivo exposure of trout to triiodothryronine (T3) or 25 the anti-thyroid agent propylthiouracil (PTU) altered THR expression in immune organs and 26 cells. 27 Effect of T3 and PTU over the relative expression of selected marker genes of immune cell 28 subpopulations was also studied. Treatments changed the relative expression of markers of 29 cytotoxic, helper and total T cells (cd4, cd8a, trb), B lymphocytes (mIgM) and macrophages 30 (csf1r). These findings suggest that the immune system of rainbow trout is responsive to 31 thyroid hormones. 32 33 34

Environmental Toxicology and Chemistry, 2003

Xenobiotics can induce cytochrome P4501A (CYP1A) by ligand binding to the aryl hydrocarbon recept... more Xenobiotics can induce cytochrome P4501A (CYP1A) by ligand binding to the aryl hydrocarbon receptor (AhR). Typical AhR ligands are polycyclic aromatic compounds with planar molecular conformation. The present work investigated the ability of the N-imidazole derivative, 1-benzylimidazole (BIM), to induce CYP1A in rainbow trout hepatocytes. Benzylimidazole increased hepatocellular CYP1A catalytic activity (determined as 7-ethoxyresorufin-O-deethylase [EROD] activity) and CYP1A mRNA in a concentration-dependent way. Computational studies on the molecular structure of BIM indicated that the energetically most stable BIM conformer has the imidazole ring and the phenyl ring in different planes, i.e., does not take a planar conformation. This property of BIM does not agree with the structural requirements of a typical AhR ligand. In line with this observation, we found that the AhR antagonist, ␣-naphthoflavone (␣NF), was not able to inhibit BIM induction of EROD activity and CYP1A mRNA, although it inhibited the induction of CYP1A by the prototypic AhR ligand, ␤-naphthoflavone (␤NF). The results suggest that transcriptional activation of CYP1A by the N-imidazole derivative, BIM, is not mediated through direct ligand binding to the AhR.

Environmental Science and Pollution Research, 1998

A number of natural and man-made chemicals possess antiestrogenic activity, i.e. they antagonize ... more A number of natural and man-made chemicals possess antiestrogenic activity, i.e. they antagonize a broad spectrum of estrogeninduced responses in vertebrates. Examples of antiestrogens include dioxin, furan and PCB congeners, certain PAHs, pesticides and indol-3-carbinol derivatives. Major mechanisms of antiestrogenicity are antagonistic action of chemicals at the estrogen receptor, or binding of chemicals to the arylhydrocarbon (Ah) receptor and subsequent interaction with estrogen-responsive genes. Toxicological consequences resulting from antiestrogenic activity have not been conclusively demonstrated to date, although antiestrogenic compounds could critically affect sensitive reproductive and developmental processes. Abbreviations : AhR = arylhydrocarbon receptor, E2 = 17Gestradiol, X = xenobiotic, E2R = estrogen receptor, ERE = estrogen responsive element on the DNA, P450 = cytochrome P450 gene or enzyme, XRE = xenobiotic (or dioxin) responsive element on the DNA

Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2012

In order to study the variability of detoxification activities associated with the cytochromes P4... more In order to study the variability of detoxification activities associated with the cytochromes P450 1A (CYP1A) and 3A (CYP3A), several continental fish farms of Oncorhynchus mykiss were routinely sampled. In fish, CYP1A plays a key role in the biotransformation of a wide variety of pollutants. This cytochrome is induced after ligand-activation of the aryl hydrocarbon receptor. CYP3A is also implicated in the metabolism of a wide variety of xenobiotics, including pharmaceuticals however its activity is mediated by the pregnane-X-receptor. CYP1A and CYP3A inductions have been widely used as biomarkers of environmental pollution in aquatic systems, in particular when measured at the enzymatic level through ethoxyresorufin-O-deethylase (EROD) and benzyloxy-4-[trifluoromethyl]-coumarin-O-debenzyloxylase (BFCOD) activities, respectively. In one of the monitored fish farms, EROD activity, which initially showed basal levels, exhibited a sharp increase difficult to explain by seasonal variability. In order to confirm the increased induction of the cytochrome activities, 32 animals were transferred to a control farm and maintained for one month. Periodic samplings of eight animals at days 0, 7, 15 and 30 were performed and both EROD and BFCOD activities in the livers measured. Under these controlled conditions, enzymatic activities associated with detoxification processes gradually decreased to basal levels indicating the presence of some factor in the fish farm inducing the cytochromes. In order to investigate possible causes of such induction both water and sediment samples, along the river feeding the fish farm, were taken and analysed by a GCxGC-TOFMS system. This system proved very useful and allowed us to identify non-target compounds in some samples, among them personal care, pharmaceutical products, and industrial chemicals (i.e. PAHs, phthalates, alkylphenolic compounds) that could be related to the observed induction.

Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2012

The widely used herbicide atrazine (ATZ) has been reported to exhibit reproductive toxicity in ra... more The widely used herbicide atrazine (ATZ) has been reported to exhibit reproductive toxicity in rats, fish and amphibians, with an avian LD(50) of 5000 mg/kg. In the present work, ATZ was administered as a single oral dose of 25 or 100 mg/kg to female European quail (Coturnix coturnix coturnix) at days 0, 5 and 10 of the experiment, being the animals sampled at days 15, 30 and 45. ATZ significantly increased the expression of hepatic estrogen receptor α (ERα) at both doses at day 30. An important increase was also observed in plasma 17β-estradiol (E2) concentrations. ATZ at 100 mg/kg increased the circulating concentration of vitellogenin (Vtg), but this effect was not related with an increase in hepatic Vtg mRNA levels. ATZ had no effect on the hepatic expression of both cytochrome P450 1A4 (CYP1A4) or the related biotransformation activity ethoxyresorufin-O-deethylase (EROD). These results led to the conclusion that ATZ provokes an estrogenic effect in sexually mature females of European quail. Further studies are necessary to establish the effect on sexual development or reproduction of female and male birds in the wild.

Chemico-Biological Interactions, 2001

Hepatic CYP1A expression in fish can be modulated by the female sex hormone, 17beta-estradiol (E2... more Hepatic CYP1A expression in fish can be modulated by the female sex hormone, 17beta-estradiol (E2), however neither the mechanism of E2 suppression of CYP1A nor the capacity for hormonal regulation to overcome CYP1A induction by xenobiotics are known. The present study investigates for the first time in fish if the estrogen receptor (ER) is involved in the suppressive action of E2 on CYP1A gene expression. The study further examines, if the E2 effect is able to overcome xenobiotic induction of CYP1A. As experimental model, in vitro cultures of rainbow trout, Oncorhynchus mykiss, hepatocytes were used. The effect of E2 on CYP1A was assessed by measuring the CYP1A-associated 7-ethoxyresorufin-O-deethylase (EROD) enzyme activity, and CYP1A mRNA contents. E2 at non-cytotoxic concentrations caused a significant time- and concentration-dependent decline of basal but not of induced hepatic EROD activities. The inhibitory action of E2 on basal CYP1A was also evident at the mRNA level. The presence of the ER antagonist tamoxifen abolished the inhibitory action of E2 on CYP1A expression. The results from these in vitro experiments provide evidence (a) that the ER is involved in the suppressive action of E2 on CYP1A, and (b) that E2 inhibitory action does not overcome xenobiotic induction of CYP1A.

Archives of Environmental Contamination and Toxicology, 2013

The effect of orally administered atrazine (25 or 100 mg/kg on days 0, 5, and 10 of the experimen... more The effect of orally administered atrazine (25 or 100 mg/kg on days 0, 5, and 10 of the experiment) was studied in European quail (Coturnix coturnix coturnix) on four non-destructive biomarkers: fecal porphyrins, blood glutathione-S-transferase, glutathione reductase, reduced glutathione, and malondialdehyde (MDA). Uroporphyrin I (UPI) and coproporphyrins I and III (CPIII) were the main porphyrins detected in feces. The lowest dose of ATZ caused a significant (P &amp;amp;amp;amp;lt; 0.05) increase in UPI and CPIII at day 5, and the highest dose of ATZ caused an induction of CPI and a significant (P &amp;amp;amp;amp;lt; 0.05) decrease in MDA levels at day 30.

Aquatic Toxicology, 2000

The aims of the present study were to assess, (1) if polyaromatic hydrocarbons (PAHs) are able to... more The aims of the present study were to assess, (1) if polyaromatic hydrocarbons (PAHs) are able to inhibit estradiol-regulated vitellogenin synthesis in fish; and (2) if this antiestrogenic activity is mediated through the binding of PAHs to the arylhydrocarbon receptor (AhR). Cultured liver cells of rainbow trout, Oncorhynchus mykiss, were co-exposed to PAHs and 17β-estradiol (E2), and the resulting effects

Aquatic Toxicology, 2008

Polycyclic aromatic hydrocarbons (PAHs) are assumed to be the primary determinant of oil petroleu... more Polycyclic aromatic hydrocarbons (PAHs) are assumed to be the primary determinant of oil petroleum toxicity. Since the PAH content in Prestige oil was relatively high, we investigated the effects of different oil fractions (crude or weathered oil −0.05 to 50 g/L, and shaken or sonicated water accommodated fractions, WAFs, 25-100%, v/v) on the embryo-larval development of medaka (Oryzias latipes). Concentrations of 16PAHs analyzed in the incubation medium were highest in the shaken WAF followed by the crude oil, the sonicated WAF and the weathered oil. Both oils (≥0.25 g/L) induced developmental abnormalities whereas no significant effects were seen in the WAF exposures. In vivo morphometric analysis of the surface of the gallbladder during advanced embryo organogenesis (192 h post-fertilization, hpf) revealed significant dilation in both WAF exposures (>3 × 10 4 m 2 at ≥25%, v/v, compared to <1.7 × 10 4 m 2 at 0%, v/v) followed by the crude oil (>2.2 × 10 4 m 2 at ≥0.05 g/L). Fluorescent aromatic compounds were observed in the gallbladder and the yolk sac of 168-hpf embryos exposed to all oil fractions. Results suggest the presence of components in both oils capable of penetrating the chorion and inducing a toxicity not observed in the WAFs. Hence, the hazard and risk assessment of Prestige oil should not be based solely on the presence of PAHs since proximity or direct contact may induce toxicity not associated exclusively to these compounds. This research offers a new hypothesis for explaining the reported biological observations, which could be correlated to direct oil exposure rather than the traditional mechanism of waterborne PAH exposure. Further research is needed to identify those oil components responsible for toxicity.