17-Beta estradiol and 4-nonylphenol delay smolt development and downstream migration in Atlantic salmon, Salmo salar

Estrogen pollution of the European aquatic environment: A critical review

Among the plethora of chemicals released into the environment, much attention is paid to endocrine disrupting compounds (EDCs). Natural estrogens, such as estrone (E1), 17β-estradiol (E2), estriol (E3) are excreted by humans as well as animals, and can enter the environment as a result of discharging domestic sewage and animal waste. These compounds can cause deleterious effects such as feminization, infertility and hermaphroditism in organisms that inhabit water bodies. This study provides an overview of the level of estrogen exposures in surface waters, groundwater and river sediments in European countries. The conducted review shows that estrogen concentrations were within the range of 0.1 ng L - 10 ng /L in the majority of the tested environmental samples. However, the authors of the study point out that there are still many unexplored areas and a limited amount of data that mainly concerns Eastern European countries. The study also analysed the factors that influence the increased emissions of estrogens to the environment, which may be helpful for identifying particularly polluted areas.

Non-Lethal Sampling Supports Integrative Movement Research in Freshwater Fish

Freshwater ecosystems and fishes are enormous resources for human uses and biodiversity worldwide. However, anthropogenic climate change and factors such as dams and environmental contaminants threaten these freshwater systems. One way that researchers can address conservation issues in freshwater fishes is via integrative non-lethal movement research. We review different methods for studying movement, such as with acoustic telemetry. Methods for connecting movement and physiology are then reviewed, by using non-lethal tissue biopsies to assay environmental contaminants, isotope composition, protein metabolism, and gene expression. Methods for connecting movement and genetics are reviewed as well, such as by using population genetics or quantitative genetics and genome-wide association studies. We present further considerations for collecting molecular data, the ethical foundations of non-lethal sampling, integrative approaches to research, and management decisions. Ultimately, we argue that non-lethal sampling is effective for conducting integrative, movement-oriented research in freshwater fishes. This research has the potential for addressing critical issues in freshwater systems in the future.

Impact of Estrogens Present in Environment on Health and Welfare of Animals

Simple Summary

Estrogens are a group of steroid hormones that recently have gained even more attention in the eyes of scientists. There is an ongoing discussion in the scientific community about their relevance as environmental contaminants and the danger they pose to animal health and welfare. In available literature we can find many examples of their negative effects and mechanisms that are involved with such phenomena.

Abstract

Nowadays, there is a growing interest in environmental pollution; however, knowledge about this aspect is growing at an insufficient pace. There are many potential sources of environmental contamination, including sex hormones—especially estrogens. The analyzed literature shows that estrone (E1), estradiol (E2), estriol (E3), and synthetic ethinyloestradiol (EE2) are the most significant in terms of environmental impact. Potential sources of contamination are, among others, livestock farms, slaughterhouses, and large urban agglomerations. Estrogens occurring in the environment can negatively affect the organisms, such as animals, through phenomena such as feminization, dysregulation of natural processes related to reproduction, lowering the physiological condition of the organisms, disturbances in the regulation of both proapoptotic and anti-apoptotic processes, and even the occurrence of neoplastic processes thus drastically decreasing animal welfare. Unfortunately, the amount of research conducted on the negative consequences of their impact on animal organisms is many times smaller than that of humans, despite the great richness and diversity of the fauna. Therefore, there is a need for further research to help fill the gaps in our knowledge.

Disruptive effects of nonylphenol on reproductive hormones, antioxidant enzymes, and histology of liver, kidney and gonads in Caspian trout smolts

The endocrine-disrupting effect of pollutants such as alkylphenols has been considered a major concern during recent years. Although the effects of nonylphenol on the reproductive hormones of fish have been investigated in several studies, the effect of this endocrine disruptor on reproductive hormones of immature fish and salmonid smolts has been less addressed. The present work studied the effects of 1, 10 and 100 μg/l concentrations of nonylphenol on the levels of plasma reproductive hormones and liver antioxidant enzymes as well as on histopathology of reproductive and non-reproductive organs of male and female Caspian brown trout (Salmo trutta caspius) smolts after 21 days of exposure. The results of the present study showed that environmentally relevant concentrations of nonylphenol affected plasma levels of sex steroids; gonadotropins, phosphorus, estradiol to testosterone ratio, and also caused histopathological lesions in liver, kidney and testis tissues of immature Caspian brown trout during smolting. Nonylphenol significantly increased the levels of estradiol in plasma of both male and female smolts exposed to nonylphenol compared with the control groups. Exposure to nonylphenol decreased testosterone and FSH levels in both genders. It has also increased plasma levels of LH in females but did not affect LH levels in male fish. Liver SOD and CAT content was decreased in nonylphenol-exposed smolts. Therefore, the release of this economically valuable and endangered species into the rivers contaminated with nonylphenol should be avoided as it can have significant effects on the development and reproductive function of smolts.

Occurrence of endocrine-disrupting chemicals (EDCs) in river water and sediment of the Mahakam River

The study was performed to examine the occurrence of endocrine disrupting chemicals (EDCs), including four steroid estrogens, one plasticizer, and three preservatives in the Mahakam River, Indonesia. The physicochemical analysis of river water and sediment quality parameters were determined as well as the concentration of EDCs. The range of values for pH, total dissolved solids (TDS), dissolved oxygen (DO), biochemical oxygen demand (BOD), total suspended solids (TSS), nitrate, ammonium, phosphate, and oil/grease in river water and sediment were higher than recommended limits prescribed by the World Health Organization's Guidelines for Drinking-water Quality (GDWQ). Bisphenol A (BPA) was the most widely found EDC with the highest concentration level at 652 ng/L (mean 134 ng/L) in the river water and ranged from ND (not detected) to 952 ng/L (mean 275 ng/L) in the sediment. Correlation analysis to investigate the relationship between the EDCs' concentrations in water and sediment also revealed a significant correlation (R² = 0.93) between the EDCs' concentrations. High concentrations of EDCs are found in urban and residential areas because these compounds are commonly found in both human and animal bodies, resulting in the disposal of EDCs into canals and rivers in urban and suburban areas, as well as livestock manure and waste that is generated from intensive livestock farming around the suburban area.

In vivo effects of 17α-ethinylestradiol, 17β-estradiol and 4-nonylphenol on insulin-like growth-factor binding proteins (igfbps) in Atlantic salmon

Feminizing endocrine disrupting compounds (EDCs) affect the growth and development of teleost fishes. The major regulator of growth performance, the growth hormone (Gh)/insulin-like growth-factor (Igf) system, is sensitive to estrogenic compounds and mediates certain physiological and potentially behavioral consequences of EDC exposure. Igf binding proteins (Igfbps) are key modulators of Igf activity, but their alteration by EDCs has not been examined. We investigated two life-stages (fry and smolts) of Atlantic salmon (Salmo salar), and characterized how the Gh/Igf/Igfbp system responded to waterborne 17α-ethinylestradiol (EE₂), 17β-estradiol (E₂) and 4-nonylphenol (NP). Fry exposed to EE₂ and NP for 21 days had increased hepatic vitellogenin (vtg) mRNA levels while hepatic estrogen receptor α (erα), gh receptor (ghr), igf1 and igf2 mRNA levels were decreased. NP-exposed fry had reduced body mass and total length compared to controls. EE₂ and NP reduced hepatic igfbp1b1, -2a, -2b1, -4, -5b2 and -6b1, and stimulated igfbp5a. In smolts, hepatic vtg mRNA levels were induced following 4-day exposures to all three EDCs, while erα only responded to EE₂ and E₂. EDC exposures did not affect body mass or fork length; however, EE₂ diminished plasma Gh and Igf1 levels in parallel with reductions in hepatic ghr and igf1. In smolts, EE₂ and E₂ diminished hepatic igfbp1b1, -4 and -6b1, and stimulated igfbp5a. There were no signs of compromised ionoregulation in smolts, as indicated by unchanged branchial ion pump/transporter mRNA levels. We conclude that hepatic igfbps respond (directly and/or indirectly) to environmental estrogens during two key life-stages of Atlantic salmon, and thus may modulate the growth and development of exposed individuals.

Characterizing pharmaceutical, personal care product, and hormone contamination in a karst aquifer of southwestern Illinois, USA, using water quality and stream flow parameters

Karst aquifers are drinking water sources for 25% of the global population. However, the unique geology of karst areas facilitates rapid transfer of surficial chemicals to groundwater, potentially contaminating drinking water. Contamination of karst aquifers by nitrate, chloride, and bacteria have been previously observed, but little knowledge is available on the presence of contaminants of emerging concern (CECs), such as pharmaceuticals. Over a 17-month period, 58 water samples were collected from 13 sites in the Salem Plateau, a karst region in southwestern Illinois, United States. Water was analyzed for 12 pharmaceutical and personal care products (PPCPs), 7 natural and synthetic hormones, and 49 typical water quality parameters (e.g., nutrients and bacteria). Hormones were detected in only 23% of samples, with concentrations of 2.2-9.1ng/L. In contrast, PPCPs were quantified in 89% of groundwater samples. The two most commonly detected PPCPs were the antimicrobial triclocarban, in 81% of samples, and the cardiovascular drug gemfibrozil, in 57%. Analytical results were combined with data of local stream flow, weather, and land use to 1) characterize the extent of aquifer contamination by CECs, 2) cluster sites with similar PPCP contamination profiles, and 3) develop models to describe PPCP contamination. Median detection in karst groundwater was 3 PPCPs at a summed concentration of 4.6ng/L. Sites clustered into 3 subsets with unique contamination models. PPCP contamination in Cluster I sites was related to stream height, manganese, boron, and heterotrophic bacteria. Cluster II sites were characterized by groundwater temperature, specific conductivity, sodium, and calcium. Cluster III sites were characterized by dissolved oxygen and barium. Across all sites, no single or small set of water quality factors was significantly predictive of PPCP contamination, although gemfibrozil concentrations were strongly related to the sum of PPCPs in karst groundwater.

Distribution and estrogenic potential of endocrine disrupting chemicals (EDCs) in estuarine sediments from Mumbai, India

Endocrine disrupting chemicals (EDCs) are responsible for inappropriate development and they alter the hormonal and homeostatic systems of organism. Phthalates (PAEs), bisphenol A (BPA) and other EDCs were monitored in surface sediments at different stations across Thane Creek, India. Analysis of PAEs was carried out using GC-MS technique, while BPA and other EDCs were analyzing on UPLC-PDA instrument. Di-n-butyl phthalate (DBP) had the highest concentration among all fourteen analyzed phthalates ranges between 0.13 and 0.4 mg kg(-1); and was detectable in all sediment samples. Strong correlation (r = 0.95, p < 0.01) was observed between total organic carbon (TOC, %) and total PAEs. BPA was also detected in all samples; average BPA concentration varies from 16.3 to 35.79 μg kg(-1) with mean value 25.15 μg kg(-1) dry weight of sediment. Synthetic EDCs such as 4-para-nonylphenol (NP) and 4-tert-octylphenol (OP) were also analyzed; and their average concentrations were founds to be 356.5 and 176 μg kg(-1), respectively. Estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2) were the main contributors to the overall estradiol equivalent concentration (EEQs) in sediment, their average total percentage contributions is more than 90 %.

Evaluating the treatment of a synthetic wastewater containing a pharmaceutical and personal care product chemical cocktail: compound removal efficiency and effects on juvenile rainbow trout

Pharmaceutical and personal care products (PPCPs) can evade degradation in sewage treatment plants (STPs) and can be chronically discharged into the environment, causing concern for aquatic organisms, wildlife, and humans that may be exposed to these bioactive chemicals. The ability of a common STP process, conventional activated sludge (CAS), to remove PPCPs (caffeine, di(2-ethylhexyl)phthalate, estrone, 17α-ethinylestradiol, ibuprofen, naproxen, 4-nonylphenol, tonalide, triclocarban and triclosan) from a synthetic wastewater was evaluated in the present study. The removal of individual PPCPs by the laboratory-scale CAS treatment plant ranged from 40 to 99.6%. While the efficiency of removal for some compounds was high, remaining quantities have the potential to affect aquatic organisms even at low concentrations. Juvenile rainbow trout (Oncorhynchus mykiss) were exposed to influent recreated model wastewater with methanol (IM, solvent control) or with PPCP cocktail (IC), or CAS-treated effluent wastewater with methanol (EM, treated control) or with PPCP cocktail (EC). Alterations in hepatic gene expression (evaluated using a quantitative nuclease protection plex assay) and plasma vitellogenin (VTG) protein concentrations occurred in exposed fish. Although there was partial PPCP removal by CAS treatment, the 20% lower VTG transcript levels and 83% lower plasma VTG protein concentration found in EC-exposed fish compared to IC-exposed fish were not statistically significant. Thus, estrogenic activity found in the influent was retained in the effluent even though typical percent removal levels were achieved raising the issue that greater reduction in contaminant load is required to address hormone active agents.

Altered burst swimming in rainbow trout Oncorhynchus mykiss exposed to natural and synthetic oestrogens

Juvenile rainbow trout Oncorhynchus mykiss were exposed to two concentrations each of 17β-oestradiol (E2; natural oestrogen hormone) or 17α-ethinyl oestradiol (EE2; a potent synthetic oestrogen hormone) to evaluate their potential effects on burst-swimming performance. In each of six successive burst-swimming assays, burst-swimming speed (Uburst ) was lower in fish exposed to 0.5 and 1 µg l(-1) E2 and EE2 for four days compared with control fish. A practice swim (2 days prior to exposure initiation) in control fish elevated initial Uburst values, but this training effect was not evident in the 1 µg l(-1) EE2-exposed fish. Several potential oestrogen-mediated mechanisms for Uburst reductions were investigated, including effects on metabolic products, osmoregulation and blood oxygen-carrying capacity. Prior to burst-swimming trials, fish exposed to E2 and EE2 for 4 days had significantly reduced erythrocyte numbers and lower plasma glucose concentrations. After six repeated burst-swimming trials, plasma glucose, lactate and creatinine concentrations were not significantly different among treatment groups; however, plasma Cl(-) concentrations were significantly reduced in E2- and EE2-treated fish. In summary, E2 and EE2 exposure altered oxygen-carrying capacity ([erythrocytes]) and an osmoregulatory-related variable ([Cl(-) ]), effects that may underlie reductions in burst-swimming speed, which will have implications for fish performance in the wild.

Environmental estrogens inhibit growth of rainbow trout (Oncorhynchus mykiss) by modulating the growth hormone-insulin-like growth factor system

Although environmental estrogens (EE) have been found to disrupt a wide variety of developmental and reproductive processes in vertebrates, there is a paucity of information concerning their effects on organismal growth, particularly postembryonic growth. In this study, we exposed juvenile rainbow trout (Oncorhynchus mykiss) to 17β-estradiol (E2) β-sitosterol (βS), or 4-n-nonylphenol (NP) to assess the effects of EE on overall organismal growth and on the growth hormone-insulin-like-growth factor (GH-IGF) system. EE treatment significantly reduced food conversion, body condition, and body growth. EE-inhibited growth resulted from alterations in peripheral elements of the GH-IGF system, which includes multiple GH receptors (GHRs), IGFs, and IGF receptors (IGFRs). In general, E2, βS, and NP reduced the expression of GHRs, IGFs, and IGFRs; however, the effects varied in an EE-, tissue-, element type-specific manner. For example, in liver, E2 was more efficacious than either βS, and NP in reducing GHR expression, and the effect of E2 was greater on GHR 1 than GHR2 mRNA. By contrast, in gill, all EEs affected GHR expression in a similar manner and there was no difference in the effect on GHR1 and GHR 2 mRNA. With regard to IGF expression, all EEs reduced hepatic IGF1 and IGF2 mRNA levels, whereas as in gill, only E2 and NP significantly reduced IGF1 and IGF2 expression. Lastly, E2 and NP reduced the expression of IGFR1A and IGFR1B mRNA expression similarly in gill and red and white muscle, whereas βS had no effect on expression of IGFR mRNAs. These findings indicate that EEs disrupt post-embryonic growth by reducing GH sensitivity, IGF production, and IGF sensitivity.

Induction and recovery of estrogenic effects after short-term 17β-estradiol exposure in juvenile rainbow trout (Oncorhynchus mykiss)

Estrogenic compounds found in the aquatic environment include natural and synthetic estrogen hormones as well as other less potent estrogenic xenobiotics. In this study, a comprehensive approach was used to examine effects on fish endocrine system endpoints during a short-term xenoestrogen exposure as well as after post-exposure recovery. Rainbow trout (Oncorhynchus mykiss) were exposed to an aqueous 17β-estradiol (E2) concentration of 0.473 μg l(-1) for 2 and 7 days (d) followed by a 14-d recovery period. At d2 and d7, plasma E2 concentrations in treated fish were 458- and 205-fold higher than in control fish and 23- and 16-fold higher than the exposure water concentration. E2 treatment resulted in significant increases in hepatosomatic index (HSI), plasma vitellogenin (VTG) protein concentrations, and liver VTG and estrogen receptor alpha mRNA levels. All of these parameters, with the exception of plasma VTG protein, returned to baseline values during the recovery period. Plasma cortisol concentrations were unaffected by treatment. This research shows varied time frames of the estrogen-responsive molecular-, biochemical-, and tissue-level alterations, as well as their persistence, in juvenile rainbow trout treated with aqueous E2. These results have implications for feral rainbow trout exposed to xenoestrogens and indicate the importance of evaluating a comprehensive suite of endpoints in assessing the impact of this type of environmental contaminant.

A facile electrochemical sensor for nonylphenol determination based on the enhancement effect of cetyltrimethylammonium bromide

A facile electrochemical sensor for the determination of nonylphenol (NP) was fabricated in this work. Cetyltrimethylammonium bromide (CTAB), which formed a bilayer on the surface of the carbon paste (CP) electrode, displayed a remarkable enhancement effect for the electrochemical oxidation of NP. Moreover, the oxidation peak current of NP at the CTAB/CP electrode demonstrated a linear relationship with NP concentration, which could be applied in the direct determination of NP. Some experimental parameters were investigated, such as external solution pH, mode and time of accumulation, concentration and modification time of CTAB and so on. Under optimized conditions, a wide linear range from 1.0 × 10⁻⁷ mol·L⁻¹ to 2.5 × 10⁻⁵ mol·L⁻¹ was obtained for the sensor, with a low limit of detection at 1.0 × 10⁻⁸ mol·L⁻¹. Several distinguishing advantages of the as-prepared sensor, including facile fabrication, easy operation, low cost and so on, suggest a great potential for its practical applications.

Estrogenic compounds decrease growth hormone receptor abundance and alter osmoregulation in Atlantic salmon

Exposure of Atlantic salmon smolts to estrogenic compounds is shown to compromise several aspects of smolt development. We sought to determine the underlying endocrine mechanisms of estrogen impacts on the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis. Smolts in freshwater (FW) were either injected 3 times over 10 days with 2 μgg(-1) 17β-estradiol (E2) or 150μgg(-1) 4-nonylphenol (NP). Seawater (SW)-acclimated fish received intraperitoneal implants of 30 μgg(-1) E2 over two weeks. Treatment with these estrogenic compounds increased hepatosomatic index and total plasma calcium. E2 and NP reduced maximum growth hormone binding by 30-60% in hepatic and branchial membranes in FW and SW, but did not alter the dissociation constant. E2 and NP treatment decreased plasma levels of IGF-I levels in both FW and SW. In FW E2 and NP decreased plasma GH whereas in SW plasma GH increased after E2 treatment. Compared to controls, plasma chloride concentrations of E2-treated fish were decreased 5.5mM in FW and increased 10.5mM in SW. There was no effect of NP or E2 on gill sodium-potassium adenosine triphosphatase (Na(+)/K(+)-ATPase) activity in FW smolts, whereas E2 treatment in SW reduced gill Na(+)/K(+)-ATPase activity and altered the number and size of ionocytes. Our data indicate that E2 downregulates the GH/IGF-I-axis and SW tolerance which may be part of its normal function for reproduction and movement into FW. We conclude that the mechanism of endocrine disruption of smolt development by NP is in part through alteration of the GH/IGF-I axis via reduced GH receptor abundance.

The effect of nonylphenol on gene expression in Atlantic salmon smolts

The parr-smolt transformation in Atlantic salmon (Salmo salar) is a complex developmental process that culminates in the ability to migrate to and live in seawater. Exposure to environmental contaminants like nonylphenol can disrupt smolt development and may be a contributing factor in salmon population declines. We used GRASP 16K cDNA microarrays to investigate the effects of nonylphenol on gene expression in Atlantic salmon smolts. Nonylphenol exposure reduced gill Na(+)/K(+)-ATPase activity and plasma cortisol and triiodothyronine levels. Transcriptional responses were examined in gill, liver, olfactory rosettes, hypothalamus, and pituitary. Expression of 124 features was significantly altered in the liver of fish exposed to nonylphenol; little to no transcriptional effects were observed in other tissues. mRNA abundance of genes involved in protein biosynthesis, folding, modification, transport and catabolism; nucleosome assembly, cell cycle, cell differentiation, microtubule-based movement, electron transport, and response to stress increased in nonylphenol-treated fish. This study expands our understanding of the effect of nonylphenol on smolting and provides potential targets for development of biomarkers.

Xenoestrogens elicit a modulation of endocannabinoid system and estrogen receptors in 4NP treated goldfish, Carassius auratus

Based on pharmacological, behavioral and neuroanatomical studies, the endocannabinoids appear to be pivotal in some important neuroendocrine regulations of both vertebrates and invertebrates. Interestingly, a well developed endocannabinoid system was recently demonstrated by us in different bonyfish brain areas which control reproduction, energy balance and stress. Fish in particular are very sensitive to different types of stressors which can heavily affect their reproductive activity and negatively reverberate on aquaculture. Since recent new data have been reported on endocrine disruptors (EDs) impact on zebrafish receptor CB1 expression, in the present research we have investigated the response of the endocannabinoid system to acute treatment with an environmental stressor such as the xenoestrogen nonylphenol (4NP) in the brain and peripheral tissues of the goldfish Carassius auratus. First of all the estrogenic effects induced by 4NP were demonstrated by a dose-dependent increase of plasma levels and gene expression of the biomarker vitellogenin, then changes in cannabinoid receptors and anandamide degradative enzyme, the fatty acid amide hydrolase (FAAH), were analysed by means of Real Time PCR. As the exposure to EDs may lead to an activation of estrogen receptors and affects the Aromatase (AROB) transcription, changes in mRNA levels for ER subtypes and AROB were also evaluated. Our results confirm in goldfish the effect of 4NP on ERα and ERβ1 receptors and point out a different sensitivity of CB1 and CB2 for this compound, suggesting distinct roles of these cannabinoid receptors in some adaptive processes to contrast stress induced by xenoestrogen exposure.

Endocrine disrupting compounds: can they target the immune system of fish?

Endocrine disruption, in particular disruption by estrogen-active compounds, has been identified as an important ecotoxicological hazard in the aquatic environment. Research on the impact of endocrine disrupting compounds (EDCs) on wildlife has focused on disturbances of the reproductive system. However, there is increasing evidence that EDCs affect a variety of physiological systems other than the reproductive system. Here, we discuss if EDCs may be able to affect the immune system of fish, as this would have direct implications for individual fitness and population growth. Evidence suggesting an immunomodulatory role of estrogens in fish comes from the following findings: (a) estrogen receptors are expressed in piscine immune organs, (b) immune gene expression is modulated by estrogen exposure, and (c) pathogen susceptibility of fish increases under estrogen exposure.

Survival and iono-regulatory performance in Atlantic salmon smolts is not affected by atrazine exposure

This study was conducted to determine the potential effects of atrazine exposure on survival and physiological performance in Atlantic salmon (Salmo salar) during the period of smoltification. This study involved two separate experiments in which juvenile Atlantic salmon were exposed to atrazine for a four day period in freshwater after which the fish were transferred to 50% seawater for two days and then to 100% seawater for five more days. The nominal concentrations of atrazine tested (1, 10 and 100 microg/L) were representative of and exceeded the levels measured in the North American freshwater environment. After seven days in seawater, fish were weighed, bled for the determination of plasma electrolyte levels, euthanized and samples collected for the determination of gonadosomatic index, muscle water content and gill Na+/K+-ATPase activity. Measured atrazine concentrations during the freshwater exposure period were 76-99% of nominal levels. There were no mortalities attributed to atrazine exposure. There were also no statistically significant differences in body weight, plasma sodium, potassium, magnesium and chloride levels, muscle water content or gill Na+/K+-ATPase activity between control and atrazine treated fish. Measurement of testis and ovary weights showed that there were no treatment effects on relative gonad size in male or female fish. These studies have shown that short term exposure to atrazine during the freshwater phase of their lifecycle had no effects on subsequent survival, body weight, relative gonad size or various measures of iono-regulatory performance in juvenile Atlantic salmon upon transfer to seawater. The concentrations of atrazine tested exceed those likely to be experienced in the natural aquatic environment suggesting that short term exposure to atrazine does not pose a risk to Atlantic salmon during the period of smoltification.

Determination of endocrine-disrupting compounds in drinking waters by fast liquid chromatography-tandem mass spectrometry

Growing attention has been recently paid to safety of food and drinking water, making necessary the adoption of policies for water sources protection and the development of sensitive and rapid analytical methods to identify micropollutants. Endocrine-disrupting compounds (EDCs) have emerged as a major issue as they alter the functioning of the endocrine system. Since ingestion of EDCs via food is considered the major exposure route, there is a growing interest in understanding EDC fate during drinking water treatment and in monitoring potential contamination of surface waters and groundwaters. In this work, a fast liquid chromatography-electrospray ionization-tandem mass spectrometry method was developed for the determination of 4-n-nonylphenol (NP), bisphenol A (BPA), estrone (E1), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) in drinking waters. In the literature analytical articles seldom provide details regarding fragmentation pathways. In this paper spectra of the five EDCs in negative ESI were interpreted with the support of accurate mass spectra acquired by a quadrupole time-of-flight instrument; fragmentation pathways were also proposed. The chromatographic separation of EDCs was optimized on a Pinnacle DB Biphenylic column with a water-acetonitrile gradient. Quantitative analysis was performed in multiple reaction monitoring (MRM) mode using bisphenol A-d(16) (BPA-d(16)) as internal standard; calibration curves showed good correlation coefficients (0.9989-0.9997). All figures of merit of the method were satisfactory; limits of detection were in the range 0.2-0.4 ng/ml. The method was applied to the determination of the analytes in waters sampled by polar organic chemical integrative samplers in a drinking water treatment plant. Rather low concentration of BPA, NP and E1 were measured in the inlet, while none of the considered EDCs was detected in the outlet.

Development of a fast liquid chromatography-tandem mass spectrometry method for the determination of endocrine-disrupting compounds in waters

A fast liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS) method was developed to study five endocrine-disrupting compounds (4-n-nonylphenol, bisphenol A, estrone, 17β-estradiol and 17α-ethinylestradiol) in water. Different columns were tested; the chromatographic separation of the analytes was optimized on a Pinnacle DB biphenylic column with a water-acetonitrile gradient elution, which allowed the separation of the selected endocrine-disrupting compounds (EDCs) in less than 6 min. Quantitative analysis was performed in selected reaction monitoring (SRM) mode; two transitions were chosen for each compound, using the most abundant for quantitation. Calibration curves using bisphenol A-d (16) as internal standard were drawn, showing good correlation coefficients (0.9993-0.9998). All figures of merit of the method were satisfactory; limits of detection were in the low pg range for all analytes. The method was then applied to the determination of the analytes in real water samples: to this aim, polar organic chemical integrative samplers (POCIS) were deployed in the influent and in the effluent of a drinking water treatment plant in Liguria (Italy). The EDC level was rather low in the influent and negligible in the outlet, reflecting the expected function of the treatment plant.

Occurrence of pharmaceutically active compounds in surface waters of the Henares-Jarama-Tajo River system (Madrid, Spain) and a potential risk characterization

The Henares-Jarama-Tajo river system is the largest drainage basin in the Province of Madrid, Spain. This area is characterized by the presence of intensive urban and industrial activities influenced by a continental Mediterranean climate with rainfalls presenting substantial fluctuations along the different seasons. This research aimed to monitor seasonal variations in concentrations of 22 pharmaceutically active compounds (PhACs) in this river system and to establish the potential risk of sublethal effects on aquatic organisms. A total of 10 sampling sites were selected along the river system with samples collected in each of the four seasons during a year-round schedule. Most of the PhACs detected were present in sampling sites downstream in the vicinity of the most populated cities (i.e. Madrid, Guadalajara and Alcalá de Henares). Only two PhACs, fluoxetine and paraxantine, were detected in all sites regardless of the season, and showed median (+/- interquartile range) concentrations of 21.4 (+/-31.2) ng L(-1) and 8.5 (+/-5.3) ng L(-1), respectively. Other PhACs were detected with a frequency >80% and included, caffeine, diphenylhydantoin, hydrochlorotiazide, ibuprofen, ketoprofen, diclofenac, sulfamethoxazole, atenolol, naproxen, carbamazepine and propanolol. Seasonal variations were observed with the highest concentrations in December and the lowest in September. By combining measured environmental concentrations with toxicity data (either publicly available or obtained experimentally in our laboratory), and by calculating an Maximum Risk Index (MaxRI) that each combination of PhACs should have for non exceeding the risk threshold, a high potential for long-term risk (MaxRI<10) was estimated for most of the sampling sites and sampling dates. This research allowed the characterization of the potential risk for each of the PhACs to exert sublethal effects on aquatic organisms using acute screening methods, justifying the need for chronic data in order to refine the risk of these compounds to aquatic organisms.

Combining passive samplers and biomonitors to evaluate endocrine disrupting compounds in a wastewater treatment plant by LC/MS/MS and bioassay analyses

Two types of integrative sampling approaches (passive samplers and biomonitors) were tested for their sampling characteristics of selected endocrine disrupting compounds (EDCs). Chemical analyses (LC/MS/MS) were used to determine the amounts of five EDCs (nonylphenol, bisphenol A, estrone, 17beta-estradiol and 17alpha-ethinylestradiol) in polar organic chemical integrative samplers (POCIS) and freshwater mussels (Unio pictorum); both had been deployed in the influent and effluent of a municipal wastewater treatment plant (WWTP) in Genoa, Italy. Estrogenicity of the POCIS samples was assessed using the yeast estrogen screen (YES). Estradiol equivalent values derived from the bioassay showed a positive correlation with estradiol equivalents calculated from chemical analyses data. As expected, the amount of estrogens and EEQ values in the effluent were lower than those in the influent. Passive sampling proved to be the preferred method for assessing the presence of these compounds since employing mussels had several disadvantages both in sampling efficiency and sample analyses.

Levels of estrogenic compounds in Xiamen Bay sediment, China

Concentrations of seven estrogenic compounds, i.e., estrone (E1), 17beta-estradiol (E2), 17 alpha-ethynylestradiol(EE2), diethylstilbestrol (DES), nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA), were determined in sediments and pore water from Xiamen Bay in China, and their distributions and potential risks in the Bay were assessed. Total estrogenic compounds concentrations varied from 49.20 to 1230.69 ng/g dw in sediments and from 102.33 to 4376.60 ng/L in pore water. The highest levels of these compounds were found at Yundang Lagoon. The results showed that estrogenic compounds in Xiamen Bay originated mainly from municipal wastewaters. Compared with other areas, Xiamen Bay was contaminated with high levels of estrogen hormones. This contamination poses a potential threat to benthic organisms. Although a good relationship (r=0.94) was observed between the estrogenic compounds concentrations and total organic carbon (TOC) contents in sediments, which did not indicate that the sediment organic matter favors the accumulation of the detected estrogenic compounds.

Determination and residual characteristic of alkylphenols in household food detergents of Taiwan

The non-ionic surfactants are mostly composed of alkylphenols for the ingredients of synthetic food detergents. Due to the ability to mimic hormones, it has been noticed that the exposures of alkylphenols might cause a variety of adverse effects. To assess the associate risks from possible exposures, concentrations of alkylphenols, including 4-nonylphenol (4-NP), technical nonylphenol isomers (t-NP(S)), and 4-tert-octylphenol (4-t-OP), in household food detergents of Taiwan were determined. Gas chromatography with mass spectrometer (GC/MS) was used to analyze alkylphenols in samples. The Taguchi experimental design was utilized to study the possible factors that might affect the residual characteristics of alkylphenols from detergents on dishware and fruits. By the analysis of variance, the orders of importance of different parameters were determined. The results showed that the concentrations of alkylphenols in food detergents ranged from 1.71 x 10(-5) to 2.13 x 10(-3) (APs/detergent, mgg(-1)). For residual characteristics, the cleaning temperature was found to be the only significant factor that will affect the 4-t-OP left on the dishware, while the concentrations of detergents used will affect the left of t-NPs and 4-NP on dishware as well. On the other hand, the varieties of fruits, the concentrations of detergents, and the concentrations of alkylphenols were found to have significant effects for the t-NPs left on fruits. As for the exposure assessments, the maximum dose of APs exposures from the use of household food detergents in Taiwan was also estimated in the study.

Endocrine disruption in aquatic vertebrates

Environmental compounds can interfere with endocrine systems of wildlife and humans. The main sink of such substances, called endocrine disrupters (ED), are surface waters. Thus, aquatic vertebrates, such as fish and amphibians, are most endangered. ED can adversely affect reproductive biology and the thyroid system. ED act by (anti)estrogenic and (anti)androgenic modes of action, resulting in abnormal sexual differentiation and impaired reproduction. These effects are mainly driven by direct interferences of ED with sex steroid receptors rather than indirectly by impacting synthesis and bioavailability of sex steroids, which in turn might affect the hypothalamic-pituitary-gonadal axis. Recent findings reveal that, in addition to the human-produced waste of ED, natural sources, such as parasites and decomposition of leaves, also might act as ED, markedly affecting sexual differentiation and reproduction in fish and amphibians. Although the thyroid system has essential functions in both fish and amphibians, amphibian metamorphosis has been introduced as the most sensitive model to detect thyroidal ED; no suitable fish model exists. Whereas ED may act primarily on only one specific endocrine target, all endocrine systems will eventually be deregulated as they are intimately connected to each other. The recent ecotoxicological issue of pharmaceutically active compounds (PhACs) present in the aquatic environment indicates a high potential for further endocrine modes of action on aquatic vertebrates by ED derived from PhACs, such as glucocorticoids, progestins, and beta-agonists.

Natural organic matter and sunlight accelerate the degradation of 17ss-estradiol in water

Nanomolar concentrations of steroid hormones such as 17beta-estradiol can influence the reproductive development and sex ratios of invertebrate and vertebrate populations. Thus their release into surface and ground waters from wastewater facilities and agricultural applications of animal waste is of environmental concern. Many of these compounds are chromophoric and susceptible to photolytic degradation. High intensity UV-C radiation has been demonstrated to degrade some of these compounds in engineered systems. However, the degradation efficacy of natural solar radiation in shallow fresh waters is less understood. Here photolytic experiments with 17beta-estradiol demonstrated modest photodegradation (~26%) when exposed to simulated sunlight between 290 and 720 nm. Photodegradation significantly increased (~40-50%) in the presence of 2.0-15.0 mg/l of dissolved organic carbon (DOC) derived from humic acids of the Suwannee River, GA. However, rates of photodegradation reached a threshold at approximately 5.0 mg/l DOC. Observed suppression of photolysis in the presence of a radical inhibitor (i.e. 2-propanol) indicated that a significant proportion of the degradation was due to radicals formed from the photolysis of DOC. Although photodegradation was greatest in full sunlight containing UV-B (290-320 nm), degradation was also detected with UV-A (320-400 nm) and visible light (400-720 nm) alone.

Development, standardization and refinement of procedures for evaluating effects of endocrine active compounds on development and sexual differentiation of Xenopus laevis

Xenopus laevis has been introduced as a model to study effects of endocrine-active compounds (EAC) on development and sexual differentiation. However, variable and inconsistent data have raised questions about the reliability of the test methods applied. The current study was conducted in two laboratories to develop, refine, and standardize procedures and protocols. Larvae were exposed in flow-through systems to 17beta-estradiol (E2), at concentrations from 0.2 to 6.0 microg E2 L(-1) in Experiment 1A, and 0.015 to 2.0 microg E2 L(-1) in Experiment 1B. In both studies survival (92%, 99%) and percentage of animals that completed metamorphosis (97%, 99%) indicated reproducible biological performance. Furthermore, minor variations in husbandry led to significant differences in snout-to-vent length, weight, and gonad size. In Experiment 1A, almost complete feminization occurred in all E2 treatment groups whereas a concentration response was observed in Experiment 1B resulting in an EC(50) of 0.12 microg E2 L(-1). The final verified protocol is suitable for determining effects of EAC on development and sexual differentiation in X. laevis.

Scents and scents-ability: pollution disrupts chemical social recognition and shoaling in fish

Chemical cues are of enormous importance in mediating the behaviour of animals, enabling them to navigate throughout their habitats, to detect the presence of predators or prey and for social recognition-identifying and discriminating between conspecifics. In many species of freshwater fish, social recognition is known to be based primarily on chemical cues. Such recognition mechanisms are vulnerable to disruption by the presence of anthropogenic contaminants in the aquatic environment. Here we show that acute exposure to low, environmentally relevant dosages of the ubiquitous contaminant, 4-nonylphenol, can seriously affect social recognition and ultimately social organization in fishes. A 1 hour 0.5 microgl-1 dose was sufficient to alter the response of members of a shoaling fish species (juvenile banded killifish, Fundulus diaphanus) to conspecific chemical cues. Dosages of 1-2 microgl-1 caused killifish to orient away from dosed conspecifics, in both a flow channel and an arena. Given the overall importance of shoaling as an adaptive strategy against predators and for locating food, it is likely that its disruption by anthropogenic contaminants would have serious implications for fishes' fitness.

Temporal trends of nonylphenol and bisphenol A contamination in the Pearl River Estuary and the adjacent South China Sea recorded by dated sedimentary cores

Three dated sedimentary cores were collected for the investigation of temporal trends and the environmental loadings of nonylphenol (NP) and bisphenol A (BPA) in recent decades in the Pearl River Estuary (PRE), South China and the adjacent South China Sea (SCS). The peak fluxes of NP and BPA occurred in the mid-1980s in the PRE, coincident with the rapid economic growth in China. The decline of NP and BPA fluxes is attributable to the implementation of sewage treatment in the late 1980s in the Pearl River Delta (PRD). Multi-model distributions were observed for the fluxes of NP and BPA in the SCS with the peak fluxes occurring in the late 1950s and the mid-1970s respectively. The fluxes of NP and BPA have increased since the 1990s due to the lack of adequate wastewater treatment facilities and the constant economic growth. Nonylphenol was quantifiably detected in sediments predating its widespread application (1940s), suggesting the downward penetration of NP in the sediment columns. The characterization results revealed that NP and BPA were preserved well and the isomer-selective degradation of NP did not occur significantly in the sediment cores. The environmental loadings of NP and BPA in the PRE sediments were roughly estimated to be 124 t and 1.7 t respectively over the past 30 years.

Effects of hexazinone and atrazine on the physiology and endocrinology of smolt development in Atlantic salmon

Exposure to hexazinone (HEX) and atrazine (ATZ), highly mobile and widely used herbicides along rivers in the United States, is potentially harmful to Atlantic salmon, which have been listed as an endangered species. To determine the effects of these contaminants on smolt development, juvenile Atlantic salmon were exposed under flow-through conditions to 100 microgl(-1) HEX, 10 and 100 microgl(-1) ATZ in fresh water (FW) for 21 days at 10 degrees C beginning in mid-April. Twelve fish per treatment were sampled in FW, following a 24h seawater (SW) challenge and after growth for 3 months in SW. Exposure to 100 microgl(-1) HEX or 10microgl(-1) ATZ caused no mortalities of smolts in FW or after SW challenge, while 9% of the fish exposed to 100 microgl(-1) ATZ died during exposure. Fish exposed to 100 microgl(-1) ATZ reduced feeding after 10 days of exposure and had an impaired growth rate in FW and during the first month in SW; compensatory growth occurred in the second and third month in SW. HEX and ATZ at 10 microgl(-1) exposure had no effect on plasma levels of cortisol, growth hormone (GH), insulin growth factor I (IGF-I), thyroxine (T(4)) and plasma 3,5,3'-triiodo-l-thyronine (T(3)), Cl(-), Mg(2+), Na(+), Ca(2+) in FW or after SW challenge. FW smolts exposed to 100 microgl(-1) ATZ had decreased plasma Cl(-), Mg(2+), Na(+) and Ca(2+) ions and increased cortisol. No effect on plasma levels of GH, IGF-I, T(4) or T(3) was found in FW smolts exposed to 100 microgl(-1) ATZ. Following SW challenge, fish previously exposed to 100 microgl(-1) ATZ had significant increases in hematocrit, plasma cortisol, Cl(-), Mg(2+), Na(+), Ca(2+) and a decrease in T(4) and T(3). It is concluded that under the conditions imposed in this study, HEX does not affect salinity tolerance of Atlantic salmon smolts, while ATZ causes ionoregulatory, growth and endocrine disturbance.

In-drop derivatisation liquid-phase microextraction assisted by ion-pairing transfer for the gas chromatographic determination of phenolic endocrine disruptors

A novel in-drop derivatisation liquid-phase microextraction procedure with an ion-pairing agent is developed and optimised for the extraction of endocrine-disrupting chemicals. The ethyl esters of the analytes were rapidly formed in the organic drop and analysed by gas chromatography. The effects of various parameters such as rate and time of agitation, ion-pairing agent and reactant concentration, pH and temperature were studied systematically to optimise the process and bring out the locale of reaction in the organic drop. A study of the mechanistic pathways of the overall procedure is attempted leading to interesting findings and delineating important points of the kinetics and mechanism. A mechanistic model is proposed on the basis of the theory of mass transfer with chemical reaction in two liquid phases. The O-ethoxycarbonyl derivatisation appears to take place in the bulk organic phase. The system provides insight into the first reported analytical case of single-drop extraction-preconcentration-derivatisation assisted by an ion-pairing transfer and has all of the interesting facets of chemical reaction in which the role of mass transfer comes into picture. The analytical features of the method are acceptable and the overall relative standard deviations of the intra-day repeatability (n=5) and inter-day reproducibility were <3.9% and <5.4%, respectively, for gas chromatography-mass spectrometry analyses and <4.3% and <7.1% for gas chromatography-flame ionisation detection analyses. The method was applicable to urine and surface water samples. The LODs ranged between 0.2-1.3 ng mL(-1) and 8.5-26.5 ng mL(-1) for GC/MS and GC/FID analyses, respectively.

Larval exposure to 4-nonylphenol and 17beta-estradiol affects physiological and behavioral development of seawater adaptation in Atlantic salmon smolts

Population declines of anadromous salmonids are attributed to anthropogenic disturbances including dams, commercial and recreational fisheries, and pollutants, such as estrogenic compounds. Nonylphenol (NP), a xenoestrogen, is widespread in the aquatic environment due to its use in agricultural, industrial, and household products. We exposed Atlantic salmon yolk-sac larvae to waterborne 10 or 100 microg L(-1) NP (NP-L or NP-H, respectively), 2 microg L(-1) 17beta-estradiol (E2), or vehicle, for 21 days to investigate their effects on smolt physiology and behavior 1 year later. NP-H caused approximately 50% mortality during exposure, 30 days after exposure, and 60 days after exposure. Mortality rates of NP-L and E2 fish were not affected until 60 days after treatment, when they were 4-fold greater than those of controls. Treatment with NP-L or E2 as yolk-sac larvae decreased gill sodium-potassium-activated adenosine triphosphatase (Na+,K(+)-ATPase) activity and seawater (SW) tolerance during smolt development, 1 year after exposure. Exposure to NP-L and E2 resulted in a latency to enter SW and reduced preference for SW approximately 2- and 5-fold, respectively. NP-L-exposed fish had 20% lower plasma insulin-like growth factor I (IGF-I) levels and 35% lower plasma triiodothyronine (T3). Plasma growth hormone and thyroxine (T4) were unaffected. Exposure to E2 did not affect plasma levels of IGF-I, GH, T3, or T4. Both treatment groups exhibited increased plasma cortisol and decreased osmoregulatory capacity in response to a handling stressor. These results suggest that early exposure to environmentally relevant concentrations of NP, and other estrogenic compounds, can cause direct and delayed mortalities and that this exposure can have long-term, "organizational" effects on life-history events in salmonids.

Effects of 17beta-estradiol and 4-nonylphenol on osmoregulation and hepatic enzymes in gilthead sea bream (Sparus auratus)

Sexually immature Sparus auratus were injected intraperitoneally with coconut oil either alone (control) or containing 17beta-estradiol (E2, 10 microg/g body mass) or 4-nonyphenol (4-NP, 100 and 200 microg/g body mass) and sampled 10 days later. Gill and kidney Na(+),K(+)-ATPase activities, plasma levels of E2 and cortisol, plasma osmolites (osmolality, sodium and chloride) and metabolites (glucose, lactate, proteins and triglycerides) were examined. Livers were used for measuring hepatosomatic index (HSI) and determinations of the activities of antioxidant defences catalase (CAT) and total glutatione peroxidase (t-GPX), the CYP1A-dependent, 7-ethoxyresorufin O-deethylase (EROD) and glutathione S-transferase (GST). HSI and plasma levels of E2 were significantly increased in E2 -treated fish. E2 treatment enhanced plasma osmolality, glucose, triglycerides and proteins, but had no effect on plasma cortisol, and gill and kidney Na(+),K(+)-ATPase activities. Hepatic activities of EROD, GST and CAT were significantly decreased after E2 administration, whereas t-GPX remained unaffected. Treatment with 200 microg/g 4-NP caused a slight increase in plasma E2 relative to the control group. Plasma glucose and protein levels were not affected by 4-NP, while triglycerides were increased. Fish treated with the higher dose of 4-NP displayed a clear reduction in kidney Na(+),K(+)-ATPase activity, together with increases in plasma osmolality, relative to the control group. High 4-NP also caused a significant decrease in EROD and an increase in GST activity. Our results confirm the regulation of the natural estrogen E2 and the weak xenoestrogen 4-NP on osmoregulation and biotransformation enzymes in a partially similar manner. The actions of xenoestrogens on critical physiological processes may have an ecological significance as it can reduce adaptability and capacity to metabolise xenobiotics under stressful conditions.

Effect of waterborne exposure to 4-tert-octylphenol and 17beta-estradiol on smoltification and downstream migration in Atlantic salmon, Salmo salar

Groups of Atlantic salmon parr (November, Exp. 1) or pre-smolts (March, Exp. 2) were exposed to estradiol-17beta (E2 conc.: nominal 500 ngl(-1)/actual 8-16 ngl(-1)) and two doses of tert-octylphenol (OP: nominal 25 microgl(-1)/actual 4.5-6.5 microgl(-1) and OP: nominal 100 microgl(-1)/actual 10-30 microgl(-1)) for 26 days in fresh water, and the effects on physiological and behavioural aspects of parr-smolt transformation were investigated. Vitellogenesis was induced by all treatments, as indicated by elevated levels of plasma vitellogenin (Vtg) and hepatosomatic index. Elevated Vtg levels were still found in OP-100 and E2-treated fish 4-5 months after cessation of treatment, indicating a slow clearance of Vtg from circulation. Smolting was compromised by E2 and OP-100 treatment as judged by reduced gill Na(+), K(+)-ATPase activity and impaired ability to regulate plasma osmolality and muscle water content in 24-h sea water (SW) challenge tests during the period of smolting. Downstream migratory behaviour was monitored from late April to July (Exp. 2) by implanting passive integrated transponder tags into subgroups of treated and control smolts and placing them in a stream raceway. Irrespective of treatment, nocturnal downstream movement was initiated in all groups on April 23, switching to diurnal movement in late May. Average swimming speed was estimated to be higher than current speed, indicating active migration. E2 and OP-100 fish migrated at lower frequency than control fish, suggesting a reduced migratory drive. The data suggests that waterborne exposure of salmon to xenoestrogens reduce both physiological and behavioural components of smoltification, even when exposure occurs several months prior to smolting.

Effect of 17beta-estradiol on gamete quality and maturation in two salmonid species

In the present study the effect of environmentally relevant concentrations of 17beta-estradiol on gamete quality and gamete maturation in rainbow trout (Oncorhynchus mykiss) and grayling (Thymallus thymallus) was investigated. Male rainbow trout were exposed to 0.5-2.5ngl(-1) 17beta-estradiol for 35days during the spawning season. At concentrations of > or =1ngl(-1) the semen volume obtained per male was significantly reduced, and after 50days also the sperm density and the sperm fertility. When male grayling were exposed to 1.0ngl(-1) 17beta-estradiol for 50days during the prespawning season a similar number of males gave semen as in the control. However, the volume of semen produced per male was decreased. The percentage of motile spermatozoa and their sperm swimming velocity were decreased while the percentage of locally motile spermatozoa was increased. In rainbow trout and grayling also the sperm motility pattern was affected by 17beta-estradiol exposure. When female rainbow trout were exposed to 0.5-2.5ngl(-1) 17beta-estradiol and egg portions were stripped in 1 week intervals the egg viability changed in a similar way as in the control indicating that egg overripening processes were not influenced by 17beta-estradiol. When female grayling were exposed to 1.0ngl(-1) 17beta-estradiol during the prespawning time ovulation occurred earlier than in the control group (group exposed to 17beta-estradiol: 35days after the onset of the experiment, control group 35-50days after the onset of the experiment).

Simultaneous determination of endocrine-disrupting phenols and steroid estrogens in sediment by gas chromatography–mass spectrometry

A simple and effective method has been developed to simultaneously determine endocrine-disrupting phenolic xenoestrogens and steroid estrogens in sediment by using ultra-sonicated extraction in combination with silica gel fractionation, derivatization with pentafluropropionic anhydride, and gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring mode (SIM). Satisfactory recoveries have been obtained for phenolic xenoestrogens and steroid estrogens. The method enables the determination of targets at concentrations of lower nanogram-per-gram in sediments. The method has been successfully applied to the sediments collected from Pearl River Estuary (PRE), South China Sea, China. Nonylphenol and bisphenol-A (BPA) were detected in the range from 204.2 to 664.5 ng/g and 0.6 to 4.0 ng/g, respectively. None of the estrogens were found in the sediment samples.

Effects of endocrine disrupters on the expression of growth hormone and prolactin mRNA in the rainbow trout pituitary

It is now widely accepted that chemical pollutants in the environment can interfere with the endocrine system of animals, thus affecting development and reproduction. Some of these endocrine disrupters (EDs) can have estrogenic or antiestrogenic effects. Most studies to date have focused on the effects of EDs on the reproductive system and sex hormones and only limited information exists on how EDs may affect pituitary gland function. A rainbow trout (Oncorhynchus mykiss) pituitary gland culture system was used for studying the effects of EDs on growth hormone (GH) and prolactin (PRL) mRNA expression. We determined that the pituitary glands actively synthesized and secreted GH and PRL over the experimental time-course. In addition, we found that treatment with 17beta-estradiol (positive control) increased levels of GH and PRL mRNA, in a concentration-dependent manner. Treatment of pituitary glands with 500 and 1000 nM of a xenoestrogen, o,p'-DDT (o,p'-dichlorodiphenyltrichloroethane), resulted in a significant induction of GH and PRL mRNA, with a 20-fold increase for PRL and 3-fold increase for GH following treatment with 1000 nM o,p'-DDT. Co-incubation of pituitary glands with ICI 182 780 (a selective estrogen receptor antagonist) and o,p'-DDT resulted in inhibition of PRL mRNA levels; however, the stimulatory effect of DDT on GH mRNA was not seen in this experiment, nor was the inhibitory effect of ICI 182 780 observed with GH mRNA. To the contrary, ICI 182 780 (2.5 nM) had a stimulatory effect on GH mRNA levels. TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin), which is known to exert antiestrogenic effects, had an estrogenic-like effect that resulted in a concentration-dependent increase in the levels of GH and PRL mRNA. Co-incubation of pituitaries with TCDD and alpha-napthoflavone (ANF), which is an inhibitor of the aryl hydrocarbon receptor (AhR), caused an inhibition of TCDD-induced PRL mRNA at the higher and lower concentrations, but these effects were less consistent on GH mRNA levels. However, the responses of PRL and GH mRNA to co-incubation with TCDD and ANF, at the various concentrations, were bi-phasic wherein stimulation was seen at the low concentrations and inhibition at the high concentrations. Combined, these results suggest that o,p'-DDT and TCDD are xenoestrogens and that their effects on the expression of GH and PRL genes in the rainbow trout pituitary are modulated, in part, through the ER and AhR, respectively.

Molecular Characterization of Estrogen Receptors 1, 2a, and 2b and Their Tissue and Ontogenic Expression Profiles in Fathead Minnow (Pimephales promelas)1

There are two estrogen receptor (ER) subtypes in fish, Esr1 and Esr2 (formerly ERalpha and ERbeta), and in some species the Esr2 subtype has two forms, Esr2b (formerly ERbeta1) and Esr2a (formerly ERbeta2 or ERgamma). There is little information, however, on the different characteristics and functional significance of the two receptor subtypes in fish, and this is especially relevant for understanding the disruption of ER signaling by chemicals with estrogenic activity. In this study, the full-length cDNAs for esr1 (3167 base pairs [bp]) and esr2b (2318 bp), and a partial-length (267 bp) cDNA for esr2a, were cloned and characterized in fathead minnow (fhm; Pimephales promelas), and their patterns of expression established during development and in adults. Real-time polymerase chain reaction revealed some clear distinctions in the ontogenic and tissue expression of fhm esr1, esr2b, and esr2a, suggesting different functions for each ER subtype. Fhm ERs were expressed in brain, pituitary, liver, gonad, intestine, and gill of male and female fish, esr2b and esr2a were also expressed in muscle. Fhm esr1 and esr2b were expressed predominantly in the liver, whereas fhm esr2a was expressed predominantly in intestine and was lowest expressed in liver. Responses of the different hepatic ERs in male fathead minnow exposed to 100 ng estradiol/L differed, with a significant induction (5-fold) of fhm esr1 but no effect on esr2b or esr2a expression, suggesting different mechanisms of regulation for the different ERs. The detailed characterization of ERs in fathead minnow provides the foundation for understanding the molecular basis of estrogenic disruption in fish.

Endocrine disruption of parr-smolt transformation and seawater tolerance of Atlantic salmon by 4-nonylphenol and 17beta-estradiol

Sex steroids are known to interfere with the parr-smolt transformation of anadromous salmonids, and environmental estrogens such as nonylphenol have recently been implicated in reduced returns of Atlantic salmon in the wild. To determine the endocrine pathways by which estrogenic compounds affect smolt development and seawater tolerance, groups of juvenile Atlantic salmon were injected with one of five doses (0.5, 2, 10, 40 or 150 microg g(-1)) of branched 4-nonylphenol (NP), 2 microg g(-1) of 17beta-estradiol (E(2)), or vehicle, during the parr-smolt transformation in April, and the treatment was repeated 4, 8, and 11 days after the first injection. Plasma was obtained for biochemical analysis 7 and 14 days after initiation of treatment. After 14 days of treatment, additional fish from each treatment group were exposed to seawater for 24h to assess salinity tolerance. The E(2) treatment and the highest NP dose resulted in lower salinity tolerance and decreased plasma insulin-like growth factor I (IGF-I) levels, along with elevated levels of plasma vitellogenin and total calcium. Plasma growth hormone levels were elevated at intermediate NP doses only, and not affected by E(2). After 7 days, plasma thyroxine (T(4)) levels decreased in a strong, dose-dependent manner in response to nonylphenol, but after 14 days, this suppressive effect of T(4) occurred at the highest NP dose only. Similarly, E(2) decreased plasma T(4) levels at 7, but not 14 days. Plasma 3,3',5-triodo-l-thyronine was reduced by E(2) and the highest NP dose after 7 and 14 days of treatment. Plasma cortisol levels were not affected by any of the treatments. The results indicate that the parr-smolt transformation and salinity tolerance can be compromised by exposure to estrogenic compounds. Suppression of plasma IGF-I levels is a likely endocrine pathway for the effects of estrogenic compounds on hypo-osmoregulatory capacity, and the detrimental effects of E(2) and NP on thyroid hormone levels are also likely to compromise the normal parr-smolt transformation of Atlantic salmon.

Distinct effects of 4-nonylphenol and estrogen-17 beta on expression of estrogen receptor alpha gene in smolting sockeye salmon

Xenoestrogens such as 4-nonylphenol (4-NP) have been shown to affect the parr-smolt transformation, but their mechanisms of action are not known. We therefore examined effects of 4-NP and estradiol-17beta (E2) on expression of estrogen receptor (ER) alpha gene in the liver, gill, pituitary and brain of sockeye salmon to elucidate molecular mechanisms of 4-NP and E2 and developmental differences in response during smolting. Fish were treated twice within a week with 4-NP (15 and 150 mg/kg BW), E2 (2 mg/kg BW) or only vehicle at three stages of smolting, pre-smolting in March, early smolting in April and late smolting in May. The absolute amounts of ERalpha mRNA were determined by real-time PCR. The basal amounts of ERalpha mRNA peaked in April in the liver, gill and pituitary. In March, E2 extensively increased the amounts in the liver, while 4-NP had no effects at this stage. In contrast, 4-NP (but not E2) decreased liver ERalpha mRNA in April. 4-NP also decreased the amount of ERalpha mRNA in the gill in April. In the pituitary, 4-NP increased ERalpha mRNA in March but decreased it in May. There were no significant effects in the brain. Changes in basal ERalpha mRNA observed in this study indicate that estrogen responsiveness of tissues may change during salmon smolting. Furthermore, 4-NP and E2 have different effects on expression of ERalpha gene in the liver and gill during smolting, and the response is dependent on smolt stage.