Effects of waterborne exposure to 4-nonylphenol on plasma sex steroid and vitellogenin concentrations in sexually mature male carp (Cyprinus carpio)

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.

Comparative developmental toxicity of eight typical organic pollutants to red sea bream (Pagrosomus major) embryos and larvae

The red sea bream (Pagrosomus major) 48-h embryo-larval bioassay was used to assess and compare the developmental toxicities of eight typical organic pollutants, including polycyclic aromatic hydrocarbons (PAHs), organophosphorus pesticides, polychlorinated biphenyls (PCBs) and alkylphenol. Toxicological endpoints such as survival rates of P. major embryos or larvae and the rates of hatching and of malformation (oedema, condensed blood, spinal curvatures or eye abnormalities) were noted and described within 48 h of exposure. The LC₅₀, EC₅₀, no-observed-effect concentration (NOEC) and lowest-observed-effect concentration (LOEC) were calculated, based on the dose-response relationship. The results showed that exposures to all of the selected organic pollutants except for methyl parathion produced acute toxic effects on P. major embryos and larvae, at different levels of exposure. The levels of acute toxicity of the eight typical organic pollutants for P. major embryos and larvae showed the following trend: benzo(a)pyrene > malathion > PCB 126 > pyrene > nonylphenol > phenanthrene > monocrotophos > methyl parathion. However, the larvae were more sensitive to these pollutants than embryos, according to the calculated LC₅₀, EC₅₀, NOEC and LOEC. This increased sensitivity of larvae could have resulted from losing the natural barrier function of the egg shell membrane. Benzo(a)pyrene, malathion, nonylphenol and monocrotophos delayed the development of P. major for both embryos and larvae, and decreased the hatching rate of the embryos. These results implied that the development of fish embryos and larvae could serve as potential biomarkers for evaluating organic contamination in the aquatic environment. The marine economic fish P. major was more sensitive to PAHs than the model fish, marine medaka (Oryzias melastigma). The estimated safe concentrations (SCs) for marine economic fish, as determined in our research, could provide a reference for the formulation of water quality criteria.

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.

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.

Effects of 4-nonylphenol on balance of steroid and thyroid hormones in sexually immature male yellowfin seabream (Acanthopagrus latus)

Nonylphenol (NP) is an endocrine disrupting chemical which has been shown to be able to modulate the endocrine system of various organisms by different mechanisms. The objective of this study was to investigate the potential effects of 4-NP on steroid and thyroid hormone levels in sexually immature male yellowfin seabream (Acanthopagrus latus), a protandrous hermaphrodite species. For this, the fish were injected with ascending doses (10, 50, 100, and 200 μg g(-1) body weight) of 4-nonylphenol (4-NP) or vehicle during 2 weeks. After 7 and 14 days the fish were anesthetized, blood sample were collected and plasma steroid and thyroid hormone concentrations were quantified by radioimmunoassay. The result showed that 4-NP induced a significant increase in 17β-etradiol levels at dose 10 μg g(-1) , while the levels of this hormone in the higher doses decreased compared with the control group. However, 4-NP treatment did not have any significant effect on plasma levels of testosterone. In addition, it was observed that 4-NP affect the level of thyroid hormones in fish. Plasma thyroxine levels increased in a dose-dependent manner after 7 and 14 days of the exposure. In contrast, a significant decrease in triiodothyronine levels was observed during the experiment period. Moreover, no significant change was detected for thyroid stimulating hormone levels in 4-NP-treated fish. These results indicated that 4-NP could lead to disturb the balance of steroid and thyroid hormones with potential consequences for sexually immature male yellowfin seabream.

In vitro and in vivo toxicities of sediment and surface water in an area near a major steel industry of Korea: endocrine disruption, reproduction, or survival effects combined with instrumental analysis

The influence of industrial and/or municipal contaminant inputs on the aquatic environment of Pohang, Korea was investigated, with a focus on bioassay combined with instrumental analysis. Pohang is the most heavily populated city in Gyeongsangbuk-do province of Korea, with more than half a million residents, and also hosts the nation's biggest steel manufacturer and related industries. Sediment (n=15) and surface water samples (n=17) were collected from Hyeongsan River which runs across the Pohang city, in two separate events, i.e., June 2010 and February 2011. Sediment samples were first Soxhlet-extracted (raw extract) and were measured for estrogenicity using H295R cell line, and also analyzed for alkylphenols (APs), bisphenol A (BPA), PAHs, and PCBs. For sediment samples which exhibited greatest effects in the cell line, further fractionation was performed into non-polar, mid-polar, and polar portions. In surface water samples, heavy metals were also analyzed. Among 15 sediment samples, station S2 near the steel industry complex and station M3 near the municipal area showed the greatest sex hormone changes, and these changes were generally explained by the fractions which contained APs and BPA. Principal component analysis (PCA) however suggests that chemicals that were not analyzed in the present study would better explain endocrine disruption capacity of sediments. In water samples, adverse effects on hatchability and growth of Japanese medaka fish, and on Daphnia reproduction were noted following exposure to six water samples collected from stations near industrial and municipal areas. Several heavy metals and nonylphenol (NP) concentrations exceeded surface water quality guidelines, suggesting adverse effects of contamination inputs from both industrial and municipal activities. Observed estrogenicities in stations such as S2 and M3 warrant further investigations on longer term ecosystem impacts near industrial and municipal areas. The levels of major organic chemicals in sediments are quite comparable to those reported in ~10 years ago, emphasizing a need for source control.

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.

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.

Environmental contaminant mixtures at ambient concentrations invoke a metabolic stress response in goldfish not predicted from exposure to individual compounds alone

Environmental contaminants from wastewater and industrial or agricultural areas are known to have adverse effects on development, reproduction, and metabolism. However, reliable assessment of environmental contaminant impact at low (i.e., ambient) concentrations using genomics and transcriptomics approaches has proven challenging. A goldfish model was used to investigate the effects of aquatic pollutant exposure in vivo by means of quantitative nuclear magnetic resonance metabolomics in multiple organs to elucidate a system-wide response. Animals were exposed to 4,4'-isopropylidenediphenol (Bisphenol-A, BPA), di-(2-ethylhexyl)-phthalate (DEHP), and nonylphenol (NP). Metabolite-specific spectral analysis combined with pathway-driven bioinformatics indicated changes in energy and lipid metabolism in liver following exposure to individual contaminants and a tertiary mixture. A dissimilar response in testis exposed to DEHP and mixture indicates disrupted AMPK and cAMP signaling. Uniquely, our observations (1) suggest that exposure to a contaminant mixture is characterized by a stress response not predicted from exposure to individual contaminants, even in the absence of other phenotypic features and (2) demonstrate the sensitivity of metabolomics in risk-assessment of environmental toxicant mixtures at ambient concentrations by detecting early stage metabolic dysregulation. These findings have general applicability in the assessment of "benign" compound mixtures in environmental and pharmaceutical development.

Effects of 17α-ethynylestradiol and nonylphenol on liver and gonadal apoptosis and histopathology in Chalcalburnus tarichi

Chalcalburnus tarichi is an endemic cyprinid fish living in the Lake Van basin located in the Eastern Turkey. Fish (3+ ages) were exposed to 17α-ethynylestradiol (EE(2); 1, 10, 100 ng L(-1); nominal concentrations) and nonylphenol (NP; 10, 60, 200 μg L(-1) ; nominal concentrations) for 32 days under semistatic daily renewal conditions. The exposure period was followed by an evaluation of liver and gonadal apoptosis and gonad histopathology in males and females. Exposure to the highest concentrations of EE(2) (100 ng L(-1)) and NP (200 μg L(-1) ) caused significant increases in the extent of apoptosis in liver and gonads. Treatment with 100 ng L(-1) of EE(2) and 200 μg L(-1) NP increased the number of TUNEL positive hepatocytes significantly in both sexes compared to controls. The rates of apoptosis in testicular germ cells and ovarian follicular cells were significantly greater at the same concentrations. Exposure to EE(2) (100 ng L(-1)) and NP (60 and 200 μg L(-1)) caused thickening of interstitial connective tissue (fibrosis) in the seminiferous tubule wall and testis-ova formation in males. In females treated with 100 ng L(-1) EE(2) , increased percentage of atretic ooctytes and fibrotic areas in the ovarian somatic stromal tissue were found in the ovaries. Increase in atresia, without a statistical significance, and fibrotic stromal tissue were also noted in 60 and 200 μg L(-1) NP treatments. Results suggest that EE(2) - and NP-dependent hepatotoxicity and gonadotoxicity are causally related to the increase in apoptosis in C. tarichi.

Evaluation of 4-nonylphenol in vivo exposure in Dreissena polymorpha: Bioaccumulation, steroid levels and oxidative stress

Nonylphenol (NP) represents the most critical metabolite of alkylphenols (APs) and alkylphenol ethoxylates (APEs), non-ionic surfactants widely used in the formulation of domestic and industrial products. On the basis of in vitro and in vivo animal studies 4-nonylphenol (4-NP) is considered an endocrine disrupting chemical (EDC). The evidence to date indicates that mollusks are able to synthesize sex steroids from the precursor cholesterol and their endocrine pathways are theoretically susceptible to disruption. The aim of this study was to investigate the endocrine modulating potency of 4-NP in the freshwater mussel Dreissena polymorpha by looking at endogenous steroid levels in control and exposed individuals. 4-NP bioaccumulation in mussels tissues and alterations in the activity of enzymes related both to oxidative stress (catalase - CAT- and glutathione peroxidase - GPX-) and phase II metabolism (glutathione-S-transferase - GST-) were also assessed. The results highlighted a build-up of 4-NP in exposed mussels and an overall decrease of 17-beta-estradiol and testosterone levels. On the other hand this chemical at the tested concentrations does not interfere with the antioxidant defense mechanisms in D. polymorpha. The mechanisms by which 4-NP alter steroids levels are unknown and require more in-depth investigations.

Sexually disrupting effects of nonylphenol and diethylstilbestrol on male silver carp (Carassius auratus) in aquatic microcosms

Based on detected nonylphenol (NP) levels in aquaculture water, this study investigated sexually disrupting effects in mature male silver carp (Carassius auratus) exposed to NP and a positive control diethylstilbestrol (DES). The combined evidences of steroid hormone (17beta-estradiol, estrone and testosterone) levels and hispathological pictures showed that NP (10 microg/L) and DES could exert estrogenic effects through indirect mechanisms [i.e. increased estrogens levels (up to two times) and decreased androgen level in serum (down to 20-30%)], which might subsequently induce vitellogenin synthesis in liver. Environmental realistic concentrations of NP might be on the verge of inducing significant estrogenic effects in male silver carps. High amounts of NP and DES might be accumulated in fish serum, and the uptake by fish was possibly responsible for their quick attenuation in experimental tank water. NP and DES might have different metabolic mechanisms, the estrogenic effects of DES were more significant than those of NP.

Impairment of the reproductive potential of male fathead minnows by environmentally relevant exposures to 4-nonylphenolf

The synthetic organic compound 4-nonylphenol (NP) has been detected in many human-impacted surface waters in North America. In this study, we examined the ability of NP to alter reproductive competence in male fathead minnows after a 28 day flow-through exposure in a range of environmentally relevant concentrations bracketing the U.S. Environmental Protection Agency toxicity-based NP chronic exposure criterion of 6.1 microg NP/L. Exposure to NP at and above the EPA chronic exposure criterion resulted in an induction of plasma vitellogenin (VTG) within 14 days. However, 7 days after the cessation of exposure, VTG concentrations had dropped more than 50% and few males expressed VTG above the detection threshold. All of the morphological endpoints, including gonadosomatic index, hepatosomatic index, secondary sexual characters, and histopathology, were unaltered by all NP treatments. However, when NP-exposed male fish were allowed to compete with control males for access to nest sites and females, most treatments altered the reproductive competence of exposed males. At lower NP concentrations, exposed males out-competed control males, possibly by being primed through the estrogenic NP exposure in a fashion similar to priming by pheromones released from female fathead minnows. At higher NP exposure concentrations, this priming effect was negated by the adverse effects of the exposure and control males out-competed treated males. Results of this study indicate the complexity of endocrine disrupting effects and the need for multiple analysis levels to assess the effects of these compounds on aquatic organisms.

Correlations of nonylphenol-ethoxylates and nonylphenol with biomarkers of reproductive function in carp (Cyprinus carpio) from the Cuyahoga River

Various chemical and biological measures were determined in carp (Cyprinus carpio) sampled from seven sites along the Cuyahoga River, Ohio; from the relatively pristine headwaters to the lower portion heavily polluted from various industrial, urban and wastewater treatment plants (WWTP). Levels of nonylphenol (NP), nonylphenol ethoxylates (NPEs; NP1EO, NP2EO) and total NPEs (NP plus the NPEs) in fish increased in a downstream direction, with maximal values observed below the discharge of the Akron WWTP. In female fish there were no significant differences between sites in GSI or levels of vitellogenin (VTG) and 17beta-estradiol (E2). However, differences were observed between sites using measures of 11-ketotestosterone (11-KT) and the ratio E2/11-KT. In male fish the highest levels of VTG were observed downstream of the Akron WWTP and a significant correlation (r=85%) between levels of NP and VTG was demonstrated. No site differences were observed in the measures of GSI, E2, 11-KT or the E2/11-KT ratio in male fish. These data suggest that endocrine active chemicals, such as, NP and NPEs are impacting fish downstream of the Akron WWTP; however, further work is warranted to separate linkages to other possible chemical factors in the water.

Protein and gene expression of VTG in response to 4-nonylphenol in rockfish (Sebastes schlegeli)

To investigate the in vivo estrogenic activity of 4-nonylphenol (4-NP) on reproductive function, we have measured the expression level of rockfish vitellogenin (rVTG) mRNA, concentration of plasma VTG and levels of plasma estradiol-17beta(E(2)) and testosterone (T) by radioimmunoassay (RIA). An rVTG mRNA transcript of approximately 4.0 kb was extracted from hepatic tissue for Northern blot analysis, and the effects of 4-NP on rVTG mRNA expression in vivo with both male and female juvenile rockfish were examined. The level of rVTG mRNA expression was increased 48 h after injection with 4-NP of 10 mg/kg body mass and after injection in both male and female rockfish. The level of rVTG mRNA expression was increased 24 h after injection in male rockfish injected with 4-NP of 25 mg/kg body mass, while the level of rVTG mRNA expression was increased 12h after injection in female injected with same dosage. Concentrations of plasma rVTG in female injected with 4-NP of 10 and 25 mg/kg b.w. were increased 72 h after injection and reached 35 and 66 mg/mL, respectively. In male, rVTG concentrations with the dosage of 25 mg/kg body mass were increased 72 h after injection and reached to 14 and 65 mg/mL at 168 h, respectively. Plasma concentrations of T and E(2) in female and male injected with 4-NP were not significantly different between two 4-NP dosages. These results suggest that 4-NP may disrupt the reproductive system of immature rockfish by acting directly on vitellogenesis. Immature females injected with 4-NP were more sensitive than immature males, but VTG in immature males is likely to return to normal conditions slowly. There are obviously large interspecies differences in response of fish to 4-NP.

Alteration of steroid hormone balance in juvenile turbot (Psetta maxima) exposed to nonylphenol, bisphenol A, tetrabromodiphenyl ether 47, diallylphthalate, oil, and oil spiked with alkylphenols

In recent years, concern has been raised about the ability of some classes of environmental contaminants to disrupt the endocrine system of both humans and wildlife. In this study, juvenile turbots (Psetta maxima) were exposed under laboratory conditions to selected waterborne contaminants: oil, oil spiked with alkylphenols, bisphenol A, diallylphthalate, tetrabrominated diphenyl ether 47, and p-nonylphenol as a positive control for "estrogenic-type" effects. This work focused on sex steroids, because these hormones play a key role in the reproduction process. Analytical procedures, involving the off-line coupling of solid phase extraction and gas chromatography/mass spectrometry, were developed for the determination of 12 endogenous sex steroids levels in fish plasma, bile, and gonads. Because of the sexual immaturity of the fish used in this study, however, only six steroids could be detected in juvenile turbots. Bisphenol A and p-nonylphenol exhibited the highest potency towards steroids dynamics, lowering the ratio of androgens to estrogens in all three studied matrices. However, these two chemicals had different modes of action, because p-nonylphenol induced a decrease of androstenedione and 11-ketotestosterone levels, whereas bisphenol A exposure led to an elevation of estrone level. Overall, these two chemicals seemingly disrupted the activity of some steroidogenesis enzymes, leading to serious hormonal imbalance in juvenile turbot.

In VivoandIn VitroExposures of Carp and Carp Tissues to Graded Concentrations of Endocrine Disrupting Chemicals

The objective of this study was to correlate morphological and biochemical parameters of reproductive activity in fish exposed to graded concentrations of endocrine disrupting chemicals. Two-year-old carps were exposed for two weeks to graded concentrations of ethynyl-estradiol, tamoxifen, and flutamide. For each chemical, morphological alterations of the gonads and liver were described according to biomarker and sex steroid levels. In parallel, isolated follicular cells (FCs) and testis fragments were incubated in the presence or absence of carp pituitary homogenate and 25-hydroxycholesterol. Media were analyzed for sex steroid level evaluations.

Plasma vitellogenin levels and gonadal morphology of wild carp (Cyprinus carpio L.) in a receiving rivers downstream of sewage treatment plants

A field study was carried out in order to assess, in a wild cyprinid fish, the biological effects related to the exposure to estrogenic compounds. The gonadosomic index (GSI), plasma vitellogenin (VTG) level and histological observations of gonads were performed to evaluate the reproductive health in common carp (Cyprinus carpio) from three rivers receiving sewage treatment plant (STP) effluents (Guadarrama, Henares and Jarama rivers, Spain) and from a reference site (Lozoya river). No significative differences in male GSI between sites were described. Only in the 18% of fish from Guadarrama river were elevated plasma VTG levels detected. The presence of oocytes in the testis was not found in any of males examined. The results suggest that the released estrogenic compounds by STPs effluents are not enough capable to adversely affect the gonadal development of the fish studied. Additional studies will be required to assess the risk of estrogenic compounds on fish from other sites of this area.

Effect of nonylphenol on plasma vitellogenin of male adult guppies (Poecilia reticulata)

Adult male guppies (Poecilia reticulata) were exposed to 4-nonylphenol (NP) at nominal concentrations of 10, 60, and 150 microg/L for 7, 14, or 21 days. Significant induction of vitellogenin (VTG) was found in male guppies exposed to 1 microg/L of 17beta-estradiol and 60 or 150 microg/L of NP after 7, 14, or 21 days. Maximum induction was seen after 14 days of treatment at these concentrations. On the other hand, significant induction of VTG in male guppies exposed to 10 microg/L of NP was observed only after 21 days of treatment. A time-dependent tendency of reduction of the gonadosomatic index (GSI) in male guppies treated with 17beta-estradiol or NP was observed, but no corresponding concentration-dependent tendency was detected. There were also no differences in the liver somatic index (LSI) of male fish treated with various concentrations of NP during the above-mentioned exposure periods. Preliminary data presented in this study strongly suggests that measurement of plasma VTG induction in male guppies is a suitable and rather sensitive indicator of exposure to estrogenic chemicals.

Effects of Nonylphenol and Triclosan on Production of Plasma Vitellogenin and Testosterone in Male South African Clawed Frogs (Xenopus laevis)

We investigated the effects of nonylphenol (NP) and triclosan (TCS) on production of vitellogenin (Vg), testosterone (T), and hepatic cytochrome P450 1A and 2B activities in male South African clawed frogs (Xenopus laevis). In a 14-d waterborne exposure test, no significant differences in the level of plasma Vg synthesis in male frogs were observed among the control, 10, 50, and 100 microg/l NP and 20, 100, and 200 microg/l TCS treatment groups. Intraperitoneal injection of male frogs with 2, 20, and 200 microg/g body weight NP resulted in no significant differences in plasma Vg levels among the control and all treatment groups. However, the levels of plasma Vg in all TCS treatment groups (intraperitoneal injection of 4, 40, and 400 microg/g body weight) were lower than that in the solvent control group, and male frogs injected with high doses of NP or TCS had lower T levels than the control group. No significant differences in hepatic cytochrome P450 1A and 2B activities were observed among the all treatment groups. Male frogs injected with 20 microg/g body weight of estradiol-17beta had significantly higher plasma Vg levels than the control group. These results suggest that profiles of plasma Vg and T production in male Xenopus laevis could be useful biomarkers for detecting hormonally active agents.

Reproductive responses of common carp (Cyprinus carpio) exposed in cages to influent of the Las Vegas Wash in Lake Mead, Nevada, from late winter to early spring

The Las Vegas Wash (LW) delivers tertiary-treated municipal wastewater effluent, nonpotable shallow groundwater seepage, and runoff from the urbanized Las Vegas Valley to Las Vegas Bay (LX) of Lake Mead. To investigate the potential for contaminants in LW influent to produce effects indicative of endocrine disruption in vivo, adult male and female common carp (Cyprinus carpio) were exposed in cages for 42-48 d at four sites in Lake Mead: LW, LX, and two reference locations in the lake. End points examined included gonadosomatic index; gonad histology; concentrations of plasma vitellogenin (VTG) and plasma sex steroids (17beta-estradiol (E2), testosterone (T), 11-ketotestosterone (11-KT)); plasma estrogen:androgen ratios (E2:T, E2:11-KT), in vitro production of T by gonad tissue, and hepatopancreas ethoxyresorufin O-deethylase activity. Few differences among fish caged at different sites were potentially attributable to exposure to contaminants