Effects of nonylphenol on juveniles and adults in the grey mullet, Liza aurata

Increased melanomacrophage centres in the liver of reproductively dysfunctional female greater amberjack Seriola dumerili (Risso, 1810)

The greater amberjack Seriola dumerili is a new aquaculture fish that may display reproductive dysfunctions. During extensive follicular atresia, which is a common reproductive dysfunction in females during vitellogenesis, part of the reabsorbed yolk returns to the liver to be metabolized and recycled. Melanomacrophage centres (MMCs) are aggregates of macrophage-like cells that play a role in the destruction, detoxification and recycling of endogenous and exogenous materials, and have been associated with systemic stress. Wild and captive-reared greater amberjack were sampled in the Mediterranean Sea during two different phases of the reproductive cycle. The liver of reproductively dysfunctional captive-reared females sampled during the spawning season showed a high density of both MMCs and apoptotic cells. A weak liver anti-cytochrome P450 monooxygenase 1A immunoreactivity was observed, suggesting that the examined fish were not exposed to environmental pollutants. We propose that the observed increase in MMCs and apoptosis in captive-reared fish was related to the hepatic overload associated to the metabolism of yolk proteins reabsorbed during extensive follicular atresia. Since follicular atresia is a frequent physiological and pathological event in teleosts, we suggest that the reproductive state should be always assessed when MMCs are used as markers of exposure to stress or pollutants.

Interactions of oxidative DNA damage and CYP1A gene expression with the liver enzymes in Klunzinger's mullet exposed to benzo[a]pyrene

Benzo[a]pyrene (B[a]P) is an important contaminant whose liver biotransformation is dependent on the species, the route of exposure and the concentration. The goal of this study was to assess the interactions of oxidative DNA damage and CYP1A gene expression with the liver enzymes in Klunzinger’s mullet (Liza klunzingeri) exposed to benzo[a]pyrene. Sublethal doses of B[a]P (5, 10 and 50 mg/kg) were intraperitoneally administered to the fish for 14 days. The alterations in antioxidant enzymes’ activity (SOD, CAT, and GPX), hepatic enzymes’ activity (ALT, AST and ALP), DNA damage (measured by comet assay and cellProfiler software) and CYP1A gene expression in the fish liver were studied on the 1st, 3rd, 7th and 14th days. The determination of these parameters in the liver showed that most of these parameters significantly increased mostly in a time-dependent manner. Multiple regression analysis showed that DNA damage and CYP1A gene expression had positive correlations with the liver enzymes in this fish species intraperitoneally exposed to these concentrations. Moreover, these interactions indicated that theses parameters are sensitive biomarkers for the exposure to B[a]P in Klunzinger's mullet. However, other possible factors and B[a]P metabolites should be considered in future studies for better elucidating the biotransformation mechanisms and introducing better biomarkers of B[a]P.

Long-term exposure to waterborne nonylphenol alters reproductive physiological parameters in economically important marine fish

Low concentrations of nonylphenol (NP) in aquatic environment can induce drastic effects on the endocrine system in animals. In this study, we examined the modulatory effects of NP on reproductive and physiological parameters in juveniles of the red seabream and black rockfish following waterborne NP exposure (0, 1, 10, and 50 μg L^-1) for 60 days. In red seabream exposed to 50 μg L^-1 NP, plasma levels of 17β-estradiol (E2) and 11-ketotestosterone (11-KT) were significantly lower at 30 and 60 days, while E2 levels were slightly higher in 10 μg L^-1-exposed individuals at day 30. Similarly, significantly lower levels of E2 and 11-KT were observed in 10 and 50 μg L^-1-exposed black rockfish at 60 days, whereas the E2 level was higher in 1 μg L^-1-exposed individuals at day 30. After exposure to NP, plasma and mRNA levels of vitellogenin (VTG) were significantly higher in both species at 30 and 60 days, similar to the inducible effects from synthetic estrogen. Plasma cortisol levels were significantly elevated by relatively higher concentrations of NP (10 and 50 μg L^-1) at 30 and 60 days. Finally, 60 days of exposure of 50 μg L^-1 NP significantly decreased the gonadosomatic index (GSI) and increased the hepatosomatic index (HSI) in both species. The results obtained from this study provide an evidence of the endocrine disrupting potential of waterborne NP on early stages of economically important marine fish. The NP-triggered endocrine modulation can induce effects on the development of reproductive and metabolic organs in fish species.

Liver melanomacrophage centres and CYP1A expression as response biomarkers to environmental pollution in European anchovy (Engraulis encrasicolus) from the western Mediterranean Sea

The goal of the present study was to verify the suitability of using melanomacrophage centres (MMCs) as response biomarkers of marine pollution in European anchovy, which are short-lived, migratory, small pelagic fish. This suitability was verified by analysing the MMC density and cytochrome P450 monooxygenase 1A (CYP1A) expression in livers of anchovies from four areas of southern Italy. Age 2 anchovies sampled from three areas exposed to pollutants of industrial/agricultural origin (Gulf of Gela, Mazara del Vallo and Gulf of Naples) showed liver areas occupied by MMCs and numbers of MMCs that were significantly higher than those in the anchovies from Pozzallo, which is a marine area not subjected to any source of pollution. Anti-CYP1A immunoreactivity was observed in the hepatocytes of all specimens sampled from the Gulf of Gela. These findings suggest the utility of liver MMCs as biomarkers of exposure to pollutants in this small pelagic fish.

Endocrine disruption, oxidative stress, and testicular damage induced by 4-nonylphenol in Clarias gariepinus: the protective role of Cydonia oblonga

Exposure to xenoestrogens like 4-nonylphenol (NP) is recognized by disrupting endocrine functions and causes reproductive dysfunction in male fish. The present study aimed at investigating the 4-nonylphenol propensity to induce oxidative stress and hormonal disturbances in male catfish and at studying the protective role of quince (Cydonia oblonga). To fulfill this aim, catfish Clarias gariepinus were exposed to pure 100 μg/L 4-NP and to quince the leaf extract added to 4-NP, both for 15 days. The 4-NP exposure induced a marked increase in 17ß-estradiol (E2), LH, and cortisol, while thyroid hormone (TSH, T3), testosterone (T), and FSH levels noticeably decreased; however, 4-NP had no effect on T4 level. Moreover, 4-NP exposure was accompanied by histological impairments in testes. Existence of 4-NP was associated with oxidative damage as evidenced by the significant increase (p < 0.05) of the enzymes, superoxidase dismutase (SOD), catalase (CAT), acetylcholinesterase (AchE), glutathione s-transferase, total antioxidant capacity (TAC), and malondialdehyde (MDA). Adding quince was effective to neutralize hormonal levels and to repair the testicular histological alterations. In response to quince remedy, the enzymes AchE and MDA reduced significantly (p < 0.05), while limited or no response was detected for other tested enzymes. Our results concluded that quince can antagonize 4-NP toxicity in catfish, confirming that quince leaf extract displayed antioxidant activities against the toxicity of hazardous chemicals.

Effect of methomyl on sex steroid hormone and vitellogenin levels in serum of male tilapia (Oreochromis niloticus) and recovery pattern

Tilapia were exposed to sub-lethal concentrations of 0, 0.2, 2, 20 or 200 μg/L for 30 days, then transferred to methomyl-free water for 18 days. E₂ , T, 11-KTand VTG in serum were examined. There were no significant changes in all the parameters in serum of tilapia exposed to 0.2 μg/L and 2 μg/L methomyl compared to the control. However, 20 μg/L and 200 μg/L have the potential to disrupt the endocrine system of male tilapia, as shown by its ability to increase VTG and E₂ and decrease T and 11-KT in serum. Thus it would appear the no observed adverse effect level for sexual steroid hormones of methomyl is lower than 2 μg/L. Recovery data showed that the effects produced by 20μg/L were reversible but not at 200μg/L. Furthermore, the sensitivity of above parameters to methomyl followed the order of VTG>E₂ >11-KT>T>GSI, suggesting VTG being the better biomarkers.

Detection of endocrine disrupting chemicals and evidence of their effects on the HPG axis of the European anchovy Engraulis encrasicolus

Natural/synthetic Endocrine Disrupting Chemicals (EDCs) may display estrogenic activity and a lower potency than 17β-estradiol. Nonetheless, their concentrations and additive effects can affect the endocrine system and reproductive processes related to the Hypothalamic-Pituitary-Gonadal (HPG) axis. Because of their persistence in both the environment and biological systems, they ultimately target multi-level predators, including humans. We detected presence and effects of xenobiotics on wild anchovy Engraulis encrasicolus in the Western Adriatic Sea. Twenty-one PCBs and five organochlorines were detected on the order of ng g^-1; vitellogenin, vitellogenin receptor and genes encoding for the zona radiata proteins were evaluated in gonad and/or liver and found transcribed in male specimens; in addition, intersex was histologically identified in the 13% of testis. Our results have developed the understanding of the European anchovy's reproductive toxicological risk and our approach could assist the comprehension of the complex dynamics of commercially relevant Teleost species.

Dietary administration of EDC mixtures: A focus on fish lipid metabolism

Many man-made chemical compounds are recognized as endocrine disruptors and once released into the environment are likely to spread and bioaccumulate in wild species. Due to their lipophilic nature, these substances pass through the cell membrane or bind to specific receptors activating physiological responses that in the long run can cause reproductive impairment, physiological disorders, including the occurrence of metabolic syndromes. One significant source of contamination is represented by the consumption of polluted food. As a consequence, different environmental pollutants, with similar or different modes of action, can accumulate in organisms and biomagnify along the food web, finally targeting humans. The aim of this study was to analyze, under controlled conditions, the effects induced by the consumption of contaminated diets, focusing on the effects exerted at hepatic level. Juvenile seabream were fed for 21days a diet enriched with different combinations of pollutants, nonylphenol (NP), tert-octylphenol (t-OP) and bisphenol A (BPA). The different diets containing 5mg/kg bw of each contaminant, were formulated as follows: NP+tOP, BPA+NP, BPA+tOP and NP+BPA+tOP (NBO). EDCs, at the doses administered, showed low biomagnification factor (BMF), suggesting that these pollutants hardly accumulate in muscles. The results obtained at hepatic level pinpointed the steatotic effect of all the administered diets, associated to a modulation of the expression of genes involved in lipid metabolism (ppars, fas, lpl, and hsl). Results were compared to those obtained in previous studies in which fish were fed single pollutants evidencing that the administration of mixture of contaminants exerts a milder lipogenic effect, highlighting the contrasting/antagonistic interaction establishing among chemicals. Noteworthy was the setup of a new chromatographic method to detect the presence of the selected chemical in fish muscle and the application of Fourier Transform Infrared (FT-IR) analysis to evaluate pollutant-induced changes in the liver macromolecular building.

Long-term effects of binary mixtures of 17α-ethinyl estradiol and dibutyl phthalate in a partial life-cycle test with zebrafish (Danio rerio)

Using 17α-ethinyl estradiol (EE2) and dibutyl phthalate (DBP) as a typical estrogen and phthalate ester, respectively, their combined in vivo effects on zebrafish (Danio rerio) were investigated from the juvenile state to the adult stage. The authors spiked EE2 (5 ng/L and 20 ng/L) and DBP (0.1 mg/L and 0.5 mg/L) either individually or in mixture. At 45 d postfertilization (dpf), the survival rate of zebrafish was comparable in all treatments. Dibutyl phthalate did not induce vitellogenin (VTG) synthesis, and no interaction was found between EE2 and DBP on VTG induction. At 90 dpf, both liver and gill were subject to more severe damage (lipid vacuoles of hepatocytes, amalgamation of gill lamellae, and clubbing at the tips of the secondary lamellae) when coexposed to these 2 chemicals, compared with single exposure. At 115 dpf, generally none of the binary mixture groups showed significantly different growth and sex ratios compared with the corresponding EE2 alone groups. In conclusion, no obvious interactions were detected between EE2 and DBP on the growth, VTG induction, or sex ratio of zebrafish, and they may act independently. However, the influence on morphology of gonad, liver, and gill induced by exposure to the mixture of EE2 and DBP was generally more potent than that by single exposure to EE2 or DBP, indicating the combined long-term harmful effects of EE2 and DBP on the development of zebrafish. Environ Toxicol Chem 2015;34:518-526. © 2014 SETAC.

Effects of individual and binary mixtures of estrogens on male goldfish (Carassius auratus)

Adverse effects of five typical environmental estrogens, namely estrone (E1), 17β-estradiol (E2), 4-n-octylphenol (4-n-OP), 4-n-nonylphenol (4-n-NP) and bisphenol A (BPA) on adult male goldfish (Carassius auratus) were investigated both individually and in binary mixtures, using serum vitellogenin (VTG) induction and gonadosomatic index (GSI) as the endpoints. Doses of individual and binary mixtures of estrogens were chosen at broad ranges. Five individual estrogens induced common dose-dependent increases of serum VTG in the experimental fish when injection doses of the estrogen series were comparatively low. The levels of VTG induction in fish descended after peaked at a certain dose of the individual estrogen. Significant GSI decreases were observed in fish treated by all dose series of E1 and E2, and comparatively high doses of 4-n-OP, 4-n-NP and BPA when compared with that of solvent control (SC). Effects of binary mixtures of the five typical estrogens on VTG induction in male goldfish were in additive manner at low-effect doses, but divergences occurred at high dose levels, with the predicted effects by additive manner exceeding those were observed. All of GSI of fish treated by the binary mixtures were about or lower than 10(-3)%. Serious atrophy of gonads was observed in all the mixture treatment groups when compared with that of SC. These findings highlight the potential reproductive risk of fish resulted from existing mixtures of hormones in the aquatic environment, and they have important implications for environmental estrogen hazard assessment.

Effects of selected xenobiotics on hepatic and plasmatic biomarkers in juveniles of Solea senegalensis

In recent years, Solea senegalensis has increasingly been used in pollution monitoring studies. In order to assess its response to some particular widespread pollutants, juveniles of S. senegalensis were administered an intraperitoneal injection of the model aryl hydrocarbon receptor agonist β-naphtoflavone (βNF) and chemicals of environmental concern, such as the fungicide ketoconazole (KETO), the lipid regulator gemfibrozil (GEM), the surfactant nonylphenol (NP) and the synthetic hormone ethinylestradiol (EE2). Two days after injection, the effect of these chemicals was followed up as alterations of hepatic microsomal activities of the cytochrome P450 (CYPs) and associated reductases, carboxylesterases (CbEs) and the conjugation enzyme uridine diphosphate glucuronyltransferase (UDPGT). In the cytosolic fraction of the liver, the effect on CbEs, glutathione S-transferase (GST) and antioxidant activities was also considered. Alterations on the endocrine reproductive system were evaluated by plasma levels of vitellogenin (VTG) and the sex steroids estradiol (E2), testosterone (T), 11-ketotestosterone (11KT) and the progestin 17α,20β-dihydroxy-4-pregnen-3-one (17,20β-P). Injection with the model compound βNF induced the hydrolysis rate of the seven CYP substrates assayed. The xenobiotic GEM induced three CYP-related activities (e.g. ECOD) and UDPGT, but depressed antioxidant defenses. EE2 induced four CYPs, more significantly ECOD and BFCOD activities. The xenoestrogens NP and EE2 altered the activities of CbE in microsomes and catalase, and were the only treatments that induced de novo VTG synthesis. In addition, the progestin 17,20β-P, was induced in NP-injected fish. None of the treatments caused statistically significant effects on steroid plasma levels. In conclusion, the CYP substrates assayed responded specifically to treatments and juveniles of S. senegalensis appear good candidates for assessing xenobiotics exposure.

A developmental hepatotoxicity study of dietary bisphenol A in Sparus aurata juveniles

Previous studies in rats have indicated that a diet enriched with Bisphenol A adversely effects metabolism and reproductive success. In rats exposed to BPA by maternal gavage, alteration in the developmental programming, higher obesity rates and reproductive anomalies were induced. Starting with this evidence, the aim of this study was to provide important insights on the effects induced by a BPA enriched diet, on the reproductive physiology and metabolism of juvenile fish, simulating the scenario occurring when wild fish fed on prey contaminated with environmental BPA. Seabream was chosen as model, as it is one of the primary commercial species valued by consumers and these results could provide important findings on adverse effects that could be passed on to humans by eating contaminated fish. A novel method for measuring BPA in the food and water by affinity chromatography was developed. Analysis of signals involved in reproduction uncovered altered levels of vtg and Zp, clearly indicating the estrogenic effect of BPA. Similarly, BPA up-regulated catd and era gene expression. A noteworthy outcome from this study was the full length cloning of two vtg encoding proteins, namely vtgA and vtgB, which are differently modulated by BPA. Cyp1a1 and EROD activity were significantly downregulated, confirming the ability of estrogenic compounds to inhibit the detoxification process. GST activity was unaffected by BPA contamination, while CAT activity was down regulated. These results collectively confirm the estrogenic effect of BPA and provide additional characterization of novel vtg genes in Sparus aurata.

Effects of nonylphenol and ethinylestradiol on copper redhorse (Moxostoma hubbsi), an endangered species

The copper redhorse, Moxostoma hubbsi, is an endangered species endemic to Quebec. The presence of contaminants, in particular endocrine disrupting chemicals (EDCs), in its habitat has been advanced as partly responsible for the reproductive difficulties encountered by the species. In the present study, immature copper redhorse were exposed to the estrogenic surfactant nonylphenol (NP; 1, 10 and 50µg/l) and the synthetic estrogen 17α-ethinylestradiol (EE2; 10ng/l) for 21 days in a flow-through system. The endpoints investigated included general health indicators (hepatosomatic index and hematocrit), thyroid hormones, sex steroids, brain aromatase activity, plasma and mucus vitellogenin (VTG), cytochrome P4501A protein expression and ethoxyresorufin-O-deethylase activity, heat shock protein 70 (HSP70) and muscle acetylcholinesterase. Exposure to 10ng EE2/l significantly increased brain aromatase activity. Exposure to 50µg NP/l resulted in a significant reduction of plasma testosterone concentrations and a significant induction of hepatic HSP70 protein expression. NP at 50µg/l also induced plasma and mucus VTG. The presence of elevated VTG levels in the surface mucus of immature copper redhorse exposed to NP, and its correlation to plasma VTG, supports the use of mucus VTG as a non-invasive biomarker to evaluate copper redhorse exposure to EDCs in the environment and contribute to restoration efforts of the species. The results of the present study indicate that exposure to high environmentally relevant concentrations of NP and EE2 can affect molecular endpoints related to reproduction in the copper redhorse.

Mugilid fish are sentinels of exposure to endocrine disrupting compounds in coastal and estuarine environments

Effects on fish reproduction can result from a variety of toxicity mechanisms first operating at the molecular level. Notably, the presence in the environment of some compounds termed endocrine disrupting chemicals (EDCs) can cause adverse effects on reproduction by interfering with the endocrine system. In some cases, exposure to EDCs leads to the animal feminization and male fish may develop oocytes in testis (intersex condition). Mugilid fish are well suited sentinel organisms to study the effects of reproductive EDCs in the monitoring of estuarine/marine environments. Up-regulation of aromatases and vitellogenins in males and juveniles and the presence of intersex individuals have been described in a wide array of mullet species worldwide. There is a need to develop new molecular markers to identify early feminization responses and intersex condition in fish populations, studying mechanisms that regulate gonad differentiation under exposure to xenoestrogens. Interestingly, an electrophoresis of gonad RNA, shows a strong expression of 5S rRNA in oocytes, indicating the potential of 5S rRNA and its regulating proteins to become useful molecular makers of oocyte presence in testis. Therefore, the use of these oocyte markers to sex and identify intersex mullets could constitute powerful molecular biomarkers to assess xenoestrogenicity in field conditions.

Developmental exposure of zebrafish (Danio rerio) to bisphenol-S impairs subsequent reproduction potential and hormonal balance in adults

In the recent years, there has been a growing concern about the production and use of bisphenol-A substitute, namely bisphenol-S (BPS). Due to its novel nature, there have been few studies addressing the ability of BPS to disrupt the endocrine system of animals. In the present study, zebrafish (Danio rerio) embryos were exposed to and reared in various concentrations of BPS (0, 0.1, 1, 10 and 100 μg/l) for 75 days. Then adult males and females were paired in spawning tanks for 7 days in clean water and the consequent effects on fish development, reproduction, plasma vitellogenin (VTG), sex steroids and thyroid hormone levels were investigated as endpoints. After 75 days of exposure, there was a skewed sex ratio in favor of females. The results also showed that body length and weight significantly decreased in males exposed to 100 μg/l of BPS. Gonadosomatic index was significantly reduced in fish at ≥ 10 μg/l. Hepatosomatic index exhibited a significant increase in both male and female fish. At ≥ 1 μg/l of BPS, plasma 17β-estradiol levels were significantly increased in both males and females. However, plasma testosterone showed a significant reduction in males exposed to 10 and 100 μg/l of BPS. A significant induction in plasma VTG level was observed in both males and females at ≥ 10 μg/l of BPS. Plasma thyroxine and triiodothyronine levels were significantly decreased at 10 and 100 μg/l of BPS in males, and at 100 μg/l in females. Egg production and sperm count were also significantly decreased in groups received 10 and 100 μg/l of BPS. Moreover, once time to hatching and hatching rates were calculated for fertilized eggs the postponed and decreased rates of hatching were observed. Taken together, these results suggest that developmental exposure to low concentrations of BPS has adverse effects on different parts of the endocrine system in zebrafish.

Liver melanomacrophage centres as indicators of Atlantic bluefin tuna, Thunnus thynnus L. well-being

Melanomacrophage centres (MMCs), located in different organs of non-mammalian vertebrates, play a role in the destruction, detoxification or recycling of endogenous and exogenous materials. Cytochrome P450 monoxygenase 1A (CYP1A) is involved in xenobiotics biotransformation, and its liver expression is considered as a biomarker for detecting exposure to environmental pollutants. Atlantic bluefin tuna (ABFT), Thunnus thynnus L., liver samples were collected from: wild animals caught in the eastern Atlantic; juveniles reared in the central Adriatic; juveniles reared in the northern Adriatic; adults reared in the western Mediterranean. The samples were processed for basic histology, histochemistry and for CYP1A immunodetection. An unexpected high density of MMCs, containing ferric iron and lipofuscin-ceroids, was detected in the juveniles sampled in the northern Adriatic Sea. These individuals showed also a strong anti-CYP1A immunopositivity in hepatocytes and in the epithelium of bile ducts. This study supports the utility of MMCs as biomarkers of fish 'health status' and gives concern for a potential contaminant accumulation in ABFT.

Predicted no-effect concentration and risk assessment for 17-[beta]-estradiol in waters of China

Contamination of the aquatic environment by EDCs has received considerable attention from scientists, government officials, and the public. E2, one of the EDCs with high estrogenic effect, has the potential to cause multiple endocrine-disrupting effects, even at small concentrations. In the present review, the toxicity of E2 to aquatic organisms was reviewed. Results of published studies show that, for aquatic species, reproductive effects were the most sensitive endpoint for E2 exposure.Although the risks posed by EDCs have caused much attention, the research on the WQC 'for EDCs is still at the initial stage. It has been suggested in several reports that the PNEC can be regarded as the most appropriate reference value for developing WQC for the EDCs. The SSD method was applied to derive PNECs that were based on reproductive effects endpoints. In the present review, 31 NOECs, based on reproductive effect endpoints for different species, were selected to construct the curve. ThePNEC value was determined to be 0.73 ng E2/L, which could protect the biodiversity of aquatic ecosystems. Moreover, 6 NOECs for multigeneration species were also analyzed in anticipation of sensitivity comparison between the Fa and the F1 generations.When multiple generations of aquatic species were exposed to concentrations no greater than 100 ng E2/L, nearly 71.4% of the F 1 generation individuals were more sensitive to the effects of E2 than those of the Fa generation. This result indicated that different generations of the same species may respond differently to EDCs exposure.Individuals of the F 1 generation were slightly more sensitive than those of the Fa generation,in general. Therefore, protecting the F1 generation of aquatic organisms is particularly important when WQC values for the EDCs are established.Considering the toxic effects of EDCs on reproduction, long-term toxic effects(viz., full-life cycle study and the most sensitive life stage) should be used in settingWQC. Unfortunately, the NOECs of E2 for multigeneration species did not meet the requirement of PNEC derivation for protecting the Fl generation. Therefore, further research results are needed on the Fl generation of aquatic species to provide more insight into what constitutes adequate protection for aquatics lives. In the present review, the PNEC values derived in the study were compared to thePNEC values developed by others, and the results showed that they were highly consistent. In addition, we also compared the PNEC value for E2 to the PNEC value for EE2, a similar estrogen, and the result was also highly consistent when their EEFs were considered. These comparisons affirmed that the method we used for deriving the PNEC value of E2 was reasonable and the PNEC values we derived were acceptable for protecting aquatic organisms. By comparing the PNEC values we calculated to actual E2 concentrations in the natural water environment, we found that E2 in surface waters may pose high risks in many countries, especially China, Japan, the USA, Great Britain, and Italy.

Environmental concentration of nonylphenol alters the development of urogenital and visceral organs in avian model

Nonylphenol (NP) is an endocrine disruptor with harmful effects including feminization and carcinogenesis on various organisms. This substance is a degradation product of nonylphenol ethoxylates (NPEO) that is used in several industrial and agricultural processes. In this paper, we examined the assessment of NP exposure on chick embryo development, using a concentration consistent with the environmental concentrations of NP. With this aim, NP (between 0.1 and 50 μg/egg) was injected into the yolk of egg through a small needle hole in the shell. We report the effect of NP on chick reproductive system development although the effect we observed is lower than those observed by exposition to other endocrine disruptors. However, histological analysis highlighted a decrease of intraluminal seminiferous surface area in 64.12% of case (P=0.0086) and an heterogeneous organization of the renal tubules when 10 μg/egg were injected. Moreover, an impairment of liver development with an abnormal bile spillage was observed when higher concentration of NP was injected (50 μg/egg).

Increased liver apoptosis and tumor necrosis factor expression in Atlantic bluefin tuna (Thunnus thynnus) reared in the northern Adriatic Sea

The Atlantic bluefin tuna Thunnus thynnus (ABFT) is intensely fished in the Mediterranean Sea to supply a prosperous capture-based mariculture industry. Liver apoptotic structures and tumor necrosis factor (TNF) gene expression were determined in: wild ABFT caught in the eastern Atlantic; juvenile ABFT reared in the central Adriatic Sea; juvenile ABFT reared in the northern Adriatic Sea; adult ABFT reared in the western Mediterranean. The highest density of liver apoptotic structures was found in the juveniles from the northern Adriatic. Two partial TNF cDNAs (TNF1 and TNF2) were cloned and sequenced. TNF1 gene expression was higher in juveniles than in adults. The highest expression of TNF2 was found in the juveniles from the northern Adriatic. These findings might be related to the juvenile exposure to environmental pollutants.

Short-term responses of selected endocrine parameters in juvenile rainbow trout (Oncorhynchus mykiss) exposed to 4-nonylphenol

The synthetic organic compound 4-nonylphenol (4-NP) has been shown to have a wide range of adverse effects on the endocrine system of various animals including fish. The present study evaluated the potential effects of 4-NP on vitellogenin (VTG) synthesis, steroid, and thyroid hormone concentrations in both juvenile male and female rainbow trout ( Oncorhynchus mykiss). Fish were exposed by intraperitoneal injection to different doses of 4-NP (1, 10, 50, and 100 μg g−1) or vehicle (coconut oil) over a period of 14 days. Blood samples were collected 7 and 14 days after initiation of treatment. Plasma VTG levels in 4-NP-treated fish were detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis as a high molecular weight protein band of 180 KDa. In addition, plasma VTG concentrations were quantified indirectly using plasma alkali-labile phosphate (ALP) and plasma calcium. Both ALP and calcium levels in plasma showed similar and parallel increase patterns after exposure to 4-NP that were significantly higher compared with controls. The analysis of plasma sex steroid levels revealed a significant increase in 17β-estradiol and testosterone in plasma of juvenile males and females, respectively. Furthermore, a significant increase was observed in plasma cortisol levels. On the other hand, 4-NP decreased both plasma triiodothyronine and thyroxine after 7 and 14 days of treatment. These results suggest that 4-NP can affect different parts of the endocrine system, which may lead to serious impairments in physiological homeostasis of juvenile rainbow trout.

Effects of exposure to oestrogenic compounds on aromatase gene expression are gender dependent in the rainbowfish, Melanotaenia fluviatilis

This study investigated the influence of two endocrine disrupting chemicals (EDCs)-an exogenous oestrogen 17β-estradiol (E2) and the oestrogen mimic 4-n-nonylphenol (NP) on the expression of aromatase transcripts in both sexes of adult Murray river rainbowfish. Reproductively active mature fish were exposed to 1, 3, and 5 μg/L E2 or 100 and 500μg/L NP for 24, 48, 72 and 96 h. The results show a significant reduction in the expression of cyp19a1a isoform in ovarian tissues with complete inhibition at the higher concentrations (3 and 5 μg/L E2; 500μg/L NP between 24 and 72 h) and at all concentrations after 96 h. There was no expression of the cyp19a1a isoform in female brain, male brain or testes in any treatment. E2 significantly increased expression of cyp19a1b in female brain except at 5 μg/L after 24h exposure. In male brain tissue E2 exposure decreased cyp19a1b expression except at 1 and 5 μg/L at 24h. NP significantly upregulated cyp19a1b in the female brain (except with 500 μg/L at 72 h) and in testes tissues. NP downregulated expression of cyp19a1b in the male brain tissue. Collectively, these observations support the hypothesis that the expression of cyp19a1b is regulated via both positive and negative feedback mechanisms, with differential modulation based on the type and concentration of the exposed oestrogens, duration of exposure, fish tissue and gender of the fish. The results also imply that exogenous oestrogens can have a disruptive effect on the steroidogenic pathway and may lead to effects on sex differentiation, sexual behaviour and reproductive cycles in this fish.

An evaluation of the combined effects of phenolic endocrine disruptors on vitellogenin induction in goldfish Carassius auratus

Phenolic compounds are widely distributed in the natural environment, typically existing as a mixture at the nanogram or microgram per liter level. Among the phenolic compounds, 4-nonylphenol, 4-t-octylphenol, bisphenol A and 2,4-dichlorophenol attract the most concern due to their abundance and risks within the natural environment. The former three chemicals are known as endocrine disruptors causing feminization in various organisms, whereas the latter one requires further clarification concerning its feminization effect. This study aims to evaluate the combined effects of these chemicals using vitellogenin protein induction in male juvenile goldfish Carassius auratus as an endpoint after 15 days of exposure. The results showed that all these chemicals can induce vitellogenin with a relative potency of 4-t-octylphenol > bisphenol A > 4-nonylphenol ≫ 2,4-dichlorophenol. 2,4-dichlorophenol showed a very weak estrogenic effect with an induction of vitellogenin concentration of <1 % of positive control, and it is therefore omitted in further tests to evaluate their combined effect. The other three chemicals were mixed in two ways, at an equipotent ratio and at an equal environmental level ratio, and their combined effects were evaluated with both the toxicity units method and concentration addition model. The resulting effect of exposure to both mixtures showed that these chemicals generally exhibited an additive effect. The ecological risk of phenolic chemicals may therefore be underestimated if based on the presence of single chemicals whereas their combined effects warrant further consideration.

Reproductive biomarkers to identify endocrine disruption in Clarias gariepinus exposed to 4-nonylphenol

The present study investigated the hormones concentrations and gonads alterations of Clarias gariepinus caused by sublethel concentrations of 4-nonylphenol (0, 0.05, 0.08 and 0.1 mg/l). The changes in the activities of the hormones after exposure to these sublethel doses of 4-nonylpenol referred to endocrine disruption in Clarias gariepinus in association with histopathological changes in reproductive tissues. The levels of thyroid stimulating hormone (TSH), triiodothyronine (T3), total thyroxine (T4), follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone concentrations significantly decreased (P<0.05) in the treated fish in comparison with control. 17-β-estradiol increased significantly (P<0.05) with 4-nonylphenol concentrations increase. Reduction in the gonadosomatic index was evident with increase of sublethal doses of 4-nonylphenol. The histopathological changes of NP-treated were recorded in gonads of Clarias gariepinus reflecting their sensitivity to NP-estrogenic like effects.

Effects of nonylphenol on vitellogenin synthesis in adult males of the spotted ray Torpedo marmorata

The aim of this investigation was to assess the effects of nonylphenol (NP), an oestrogen-like environmental pollutant, on the vitellogenin (VTG) synthesis in adult males of the aplacental viviparous cartilaginous fish Torpedo marmorata. The VTG recovery in males is considered a biomarker of xeno-oestrogenic pollution as this lipophosphoglycoprotein is physiologically induced by oestrogens only in females of oviparous and ovoviparous vertebrates. Using in situ hybridization and immunohistochemistry, T. marmorata males injected with nonylphenol showed the presence of VTG in the liver and the kidney. In particular, vtg messenger (m)RNA and VTG protein were expressed in the liver, whereas in the kidney cells only the presence of VTG was recorded. By contrast, no expression for VTG was detected in the testis. These results demonstrate that in T. marmorata NP induces the expression of vtg only in the liver; the presence of VTG in the kidney and its absence in the testis are discussed.

Expression of vitellogenin in the testis and kidney of the spotted ray Torpedo marmorata exposed to 17β-estradiol

In vertebrates, the liver was long thought to be the only site of vitellogenin (Vtg) production, but recent studies demonstrated that Vtg is also expressed in extrahepatic districts. The aim of this paper is to assess, by in situ hybridization and immunohistochemistry, the expression of Vtg in the testis and kidney of Torpedo marmorata exposed to 17β-estradiol (E(2)). In treated samples vtg mRNA and Vtg were detected contemporaneously only in the testis; differently the kidney cells were positive to Vtg antibody, but negative to vtg mRNA. This is the first study to assess that male germ cells, after an exposure to E(2), synthesize Vtg in a stage-dependent manner. The presence of Vtg and the modifications observed in the kidney after E(2) treatment are discussed.

Assessment of estrogenic contamination and biological effects in Lake Taihu

Lake Taihu is the third largest freshwater lake in China and is contaminated with xenoestrogens associated with high population density, intensive livestock and aquatic breeding activities. A field study in Lake Taihu was conducted using the goldfish (Carassius auratus) as an indicator organism. Several biological markers were selected to assess the extent of estrogenic contamination. Changes in serum vitellogenin (VTG), and gill 7-Ethoxyresorufin-O-deethylase (EROD), glutathione-S-transferase (GST) and reduced glutathione (GSH) were measured in caged juvenile goldfish for 28 days in seven locations in northern Lake Taihu. Bioassay showed VTG increased 0.64-2.42 folds over time in goldfish collected from five stations and GSH decreased in samples from all seven stations after 7 days of exposure. EROD levels increased continually in fish collected at all the seven stations and the highest concentrations occurred at day 21. GST activity increased significantly at 7 days. The concentration of the target estrogens estrone (E(1)), 17β-estradiol (E(2)), ethinylestradiol (EE(2)), octylphenol (OP), diethylstilbestrol (DES), nonylphenol (NP) and bisphenol A (BPA) were determined in lake water at the sampling stations. Each individual estrogen concentration measured was multiplied by its relative potency to gain the estradiol equivalent (EEQ). There was an obvious correlation between the concentration of VTG and the total EEQ for all seven locations (P < 0.001). The biomarker VTG, EROD, GST and GSH assays and chemical analysis might be used to illustrate the potential risk in Lake Taihu.

Environmental contaminant effects on juvenile striped bass in the San Francisco Estuary, California, USA

The decline of pelagic organisms in the San Francisco Estuary (SFE) (California, USA) is attributed to several factors, including water diversions, invasive species, and exposure to environmental toxicants. The present study evaluated the effects of environmental contaminants on liver vitellogenin, metallothionein, 7-ethoxyresorufin-O-deethylase (EROD), and benzyloxyresorufin O-deethylase (BROD) activity in juvenile striped bass (Morone saxitilis) in the SFE. Analysis of juvenile striped bass liver extracts revealed site-specific elevations of vitellogenin, metallothionein, and EROD biomarkers across the estuary. Although some striped bass in the estuary showed EROD activity similar to unhandled hatchery controls, several sites in the estuary showed significantly higher EROD activity that was in the range of beta-naphthoflavone (BNF)-injected, positive controls. Overall, EROD activity averaged 283% higher in estuary fish than in hatchery controls. Chemical analyses of extracts from semipermeable membrane devices (SPMDs) deployed in the estuary for one month showed elevated polyaromatic hydrocarbon (PAH) levels. Semipermeable membrane devices extract injections-induced metallothionein and BROD in striped bass livers. These data show that environmental exposures are impacting EROD and other biomarkers in the SFE striped bass population. Previous studies in our laboratory have associated poor larval development with maternal transfer of environmental contaminants. Further studies are needed to monitor contaminant exposures by the use of biomarkers and to integrate them into a more effective pelagic species recovery plan in the SFE.

Assessment of in vivo estrogenic response and the identification of environmental estrogens in the Yangtze River (Nanjing section)

Environmental estrogens in the aquatic environment have been shown to be responsible for the feminization of fish. The estrogenic content of the Yangtze River (Nanjing section--referred to as the studied area herein) was assessed using a combination of bioassay and chemical analysis. The in vivo bioassay was conducted by exposing adult male goldfish (Carassius auratus) to different concentrations of river water (25%, 50% and 100%) sampled from three representative sections of the studied area. Chemical analysis of estrogens in water from the three representative sections was conducted using solid phase extraction-gas chromatograph (SPE-GC) detection. The assay showed significant serum vitellogenin (VTG) and 17beta-estradiol (E2) induction and gonad atrophy in the treated fish. The strength of in vivo estrogenic responses in the three representative sections is in the order of Jiangxinzhou section>Daqiao section>Sanchahe section. The result is consistent with the levels of water estrogens determined from the chemical analysis. Steroidal estrogens were the major causal agents responsible for the estrogenic responses in the Jiangxinzhou and Daqiao sections, while phenolic estrogens were the main contributors in the Sanchahe section. The results of these in vivo bioassay and chemical analysis demonstrate that fish in the Yangtze River are exposed to environmental estrogens and are at a risk of feminization.

The relevance of temporal and organ specific factors on metals accumulation and biochemical effects in feral fish (Liza aurata) under a moderate contamination scenario

Moderate contamination scenarios are nowadays challenging ecotoxicologists. An investigative biomonitoring study was performed under those environmental conditions (Obidos lagoon, Portugal) focused on oxidative stress and accumulated metals in Liza aurata liver and kidney, also examining winter-summer variations and organ-specificities. Three sites were surveyed: Barrosa; Bom-Sucesso; Middle lagoon. The higher metal availability at Barrosa (in water and sediment) was reflected in both organ burdens, though liver was more responsive. Oxidative stress (both organs) pointed to a pro-oxidant challenge at Barrosa (both seasons), reinforced by a general stress index. In winter, oxidative stress at Barrosa was related with accumulated metals in both organs, while in summer this cause-effect relationship was only established for kidney since changes in liver were linked with non-contaminant related variables. Winter-summer variations were outstanding in liver and kidney oxidative stress endpoints, pointing to the relevance of considering distinct seasons and organs in the assessment of moderately contaminated systems.

Combined use of environmental data and biomarkers in fish (Liza aurata) inhabiting a eutrophic and metal-contaminated coastal system - Gills reflect environmental contamination

An investigative biomonitoring study was carried out in a eutrophic coastal system with a moderate contamination by metals (Obidos lagoon, Portugal), combining the evaluation of exposure concentrations with metals accumulation and oxidative stress responses in gills of the golden grey mullet (Liza aurata). Two contrasting seasons (winter and summer) were considered at three sites: Barrosa (BB) and Bom-Sucesso (BS) branches; Middle lagoon (ML). Data on the water column pointed to a higher metals and nutrients availability at BB that was reflected in the higher metal concentrations in gills, particularly in winter. Similarly, oxidative stress responses demonstrated a pro-oxidant challenge at BB (winter and summer), which was corroborated by an integrated biomarker response index (IBR). Metal concentrations in gills were higher in summer than winter, reflecting the increased environmental concentrations in combination with elevated metabolic rates. Catalase (CAT), glutathione-S-transferase (GST), total glutathione (GSH(t)) and lipid peroxidation (LPO) increases observed in winter at BB were related with metal accumulation, while summer enhancement of glutathione peroxidase (GPx), glutathione reductase (GR), GST and GSH(t) was associated with other stressors. Inter-site differences on the basis of IBR were more accentuated in winter. Gills can be considered as an important route of entry for contaminants and were demonstrated to reflect water contamination and are therefore useful in the context of environmental assessment.

Thyroid hormones as a potential early biomarker of exposure to 4-nonylphenol in adult male shubunkins (Carassius auratus)

Nonylphenol, an estrogenic-like compound, can induce vitellogenin synthesis in males and immature Teleostean species, but little is known about its effects on thyroid hormones balance. The present study evaluated the potential effects of a single acute exposure to nonylphenol (i.p. injected) on the thyroid and reproductive axis of 250 shubunkins (Carassius auratus). Plasma levels of thyroid hormones were quantified immunoenzymatically by ELISA assay. Nonylphenol induced a significant decrease of thyroxin levels, whereas no effect on triiodothyronine concentrations was detected. No histopathological changes were detected in thyroid or testes. The toxicological data confirmed that nonylphenol exerts an estrogenic effect on male fish. In addition, nonylphenol was suspected to inhibit the thyroid hormones balance, suggesting the thyroid should be included among the other endocrine glands susceptible to endocrine disruption.

Effects of 17alpha-ethynylestradiol on EROD activity, spiggin and vitellogenin in three-spined stickleback (Gasterosteus aculeatus)

The three-spined stickleback (Gasterosteus aculeatus) has quantifiable biomarkers of exposure to estrogens (vitellogenin), androgens (spiggin) and aryl hydrocarbon receptor (AhR) agonists (EROD activity) and is therefore a promising test species for biomonitoring of reprotoxic chemicals in aquatic environments. In this study we evaluated the effects of 17alpha-ethynylestradiol (EE(2)) on EROD activity, induction of vitellogenin and spiggin, hepatosomatic index (HSI), ovarian somatic index (OSI) and nephrosomatic index (NSI). Adult male and female three-spined sticklebacks were exposed to concentrations of 0-170 ng EE(2)/l (measured concentrations) in a flow-through system for 21 days. Exposure to 170 ng EE(2)/l resulted in a significant 8- and 9-fold induction of gill EROD activity in males and females, respectively. In livers, EROD activity expressed in relation to microsomal protein content was suppressed due to a significant increase in microsomal protein content. Hepatic EROD activity per se expressed as picomol/min was not affected by exposure to EE(2). The lowest observed effect concentration for induction of vitellogenin in males was 53.7 ng EE(2)/l. In females, vitellogenin levels were significantly higher in those exposed to 170 ng EE(2)/l compared to controls. Spiggin production was significantly inhibited and NSI lower in males exposed to 170 ng EE(2)/l. In both females and males LSI was significantly higher in fish exposed to 170 ng EE(2)/l than in controls. In females exposed to 170 ng EE(2)/l, OSI was significantly lower and NSI higher than controls. The observed results from this study show that a synthetic estrogen can affect the well-known biomarker of exposure for dioxin-like compounds, EROD activity, and further that this response can differ between tissues. These findings are important for interpretation of biomonitoring data.