The effect of 4-nonylphenol on semen quality, viability of gametes, fertilization success, and embryo and larvae survival in rainbow trout (Oncorhynchus mykiss)

A Review on Environmental Contaminants-Related Fertility Threat in Male Fishes: Effects and Possible Mechanisms of Action Learned from Wildlife and Laboratory Studies

Increasing global rates of diminished fertility in males has been suggested to be associated with exposure to environmental contaminants (ECs). The aquatic environments are the final repository of ECs. As the reproductive system is conserved in vertebrates, studies on the effects of ECs on fertility endpoints in fishes provide us with valuable information to establish biomarkers in risk assessment of ECs, and to understand the ECs-related fertility threat. The aim of the present review was to evaluate associations between ECs and fertility determinants to better understand ECs-related male fertility threat in male fishes. Wildlife studies show that the reproductive system has been affected in fishes sampled from the polluted aquatic environment. The laboratory studies show the potency of ECs including natural and synthetic hormones, alkylphenols, bisphenols, plasticizers, pesticides, pharmaceutical, alkylating, and organotin agents to affect fertility determinants, resulting in diminished fertility at environmentally relevant concentrations. Both wildlife and laboratory studies reveal that ECs adverse effects on male fertility are associated with a decrease in sperm production, damage to sperm morphology, alternations in sperm genome, and decrease in sperm motility kinetics. The efficiency of ECs to affect sperm quality and male fertility highly depends on the concentration of the contaminants and the duration of exposure. Our review highlights that the number of contaminants examined over fertility tests are much lower than the number of contaminants detected in our environment. The ECs effects on fertility are largely unknown when fishes are exposed to the contaminants at early developmental stages. The review suggests the urgent need to examine ECs effects on male fertility when a fish is exposed at different developmental stages in a single or combination protocol. The ECs effects on the sperm genome are largely unknown to understand ECs-related inheritance of reproductive disorders transmitted to the progeny. To elucidate modes of action of ECs on sperm motility, it is needed to study functional morphology of the motility apparatus and to investigate ECs-disrupted motility signaling.

Aluminum at environmental concentrations affects the sperm quality of the freshwater teleost Astyanax altiparanae: An in vitro study

Aluminum (Al) is present in rivers and reservoirs in concentrations above that is allowed by regulatory agencies (e.g. 0.5 mg L^-1 Al), which can impair fish reproduction. The present study evaluated the in vitro effects on the sperm of Astyanax altiparanae upon Al exposure at different concentrations (0, 0.05, 0.1, 0.3, and 0.5 mg L^-1) with various exposure periods (50 s, 10 min, and 30 min). The following biomarkers were evaluated: membrane vitality, DNA fragmentation, morphology, kinetics (10 s and 30 s after sperm activation), and sperm mitochondrial activity. Al damages the membrane vitality of gametes at 0.3 and 0.5 mg L^-1 after 50 s of exposure. After 30 min of exposure, there was a decrease in membrane vitality at 0.1 and 0.5 mg L^-1, and the membrane vitality decreased with increased exposure time. Within 30 s after sperm activation, Al (0.3 and 0.5 mg L^-1) reduced sperm motility by more than 50% at the longest exposure time, while at 0.1 and 0.5 mg L^-1, Al exposure reduced motility over time. The average path speed (VAP; 10 s post-sperm activation) was reduced at longer exposure times at 0.05 and 0.5 mg L^-1 of Al. Increased exposure time had deleterious effects on mitochondrial activity at the highest concentrations tested. Al did not damage DNA and sperm morphology. In conclusion, Al negatively influences the sperm quality of A. altiparanae with a potential effect of exposure time and increasing concentrations.

Cloning and expression analysis of GATA1 gene in Carassius auratus red var

BACKGROUND

GATA1 is a key transcription factor in the GATA family, and promotes the differentiation and maturation of red blood cell, which is essential for normal hematopoiesis.

RESULTS

Our results showed that the cDNA sequence of GATA1 was 2730 bp long encoding 443 amino acids. qRT-PCR analysis demonstrated that GATA1 had the highest expression in testis (T), followed by pituitary (P) and spleen (S). GATA1 gene expression in C. auratus red var. embryo from the neuroblast stage (N) to the embryo hatching (H) changes continuously; and the gene expression levels of nonylphenol (NP)-treated and those of control embryos were significantly different. Moreover, Methylation levels of GATA1 gene in NP-treated embryos were higher than those in control embryos, indicating that NP affected GATA1 methylation.

CONCLUSIONS

Our study provides cues for further studying the roles of GATA1 gene in fish development, and suggested a potential molecular mechanism by which NP leads to abnormal development of fish embryos.

DNA of crayfish spermatozoa as a target of waterborne pesticides - An ex vivo approach as a tool to short-term spermiotoxicity screening

The spermiotoxic properties of aquatic contaminants might be the cause of low fertilization rate and decreased prolificacy, affecting the success of the impacted populations. The genotoxic potential of pesticides in spermatozoa as an undesirable effect on non-target organisms, namely aquatic invertebrates with external fertilization, emerges as a key question in ecogenotoxicological research. Thus, this study aimed to clarify if DNA integrity of red swamp crayfish (Procambarus clarkii) spermatozoa is affected by waterborne pesticides at environmentally relevant concentrations. By adopting an ex vivo approach, six pesticides were addressed in a short-term assay: herbicides glyphosate (9 and 90 μg L^-1) and penoxsulam (2.3 and 23 μg L^-1); insecticides dimethoate (2.4 and 24 μg L^-1) and imidacloprid (13.1 and 131 μg L^-1); fungicides pyrimethanil (2.2 and 22 μg L^-1) and imazalil (16 and 160 μg L^-1). Genotoxicity was observed in higher concentrations of glyphosate, penoxsulam, dimethoate, pyrimethanil, and imazalil. Imidacloprid was the only pesticide that did not cause non-specific DNA damage, although displaying pro-oxidant properties. Overall, the present study demonstrated the suitability of the ex vivo approach on spermiotoxicity screening, highlighting the potential ecological impact of pesticides on non-target species, such as P. clarkii, compromising sperm DNA integrity and, subsequently, the population success.

Investigation of Fertilizing Capacity of Zebrafish (Danio rerio) Sperm Exposed to Heavy Metals

The objective of our study was to investigate the effects of heavy metals on the fertilizing capacity of exposed zebrafish sperm, on embryonic survival, and on occurrence of embryonic deformities following fertilization with exposed sperm. It is important to test heavy metals because they are well-known pollutants. Sperm of externally fertilizing species can get in contact with pollutants found in aquatic environment. Zebrafish sperm, despite its advantages, has seldom been used in in vitro toxicological studies and no reports are available regarding the fertilizing capacity of exposed sperm. Zebrafish sperm was stripped and exposed to concentrations of the tested heavy metals (Zn²⁺, Cd²⁺, Cr³⁺, Cu²⁺, Ni²⁺, Hg²⁺, As³⁺) for 30 or 120 minutes. Calculated half-maximal effective concentration (EC₅₀) values do not differ significantly from those calculated for motility for any of the tested heavy metals, which means fertilization rate can indicate the toxicity of the given substance following exposure of sperm. Thus, its application as in vitro toxicological end point is reasonable. The survival of embryos and embryonic development have not been affected by the exposure of spermatozoa, which means all alterations in spermatozoa caused by heavy metals have been expressed before 24 hours post fertilization.

Chronic toxicity of endocrine disrupting chemicals used in plastic products in Korean resident species: Implications for aquatic ecological risk assessment

In this study, chronic toxicity of three endocrine disrupting chemicals (EDCs) used to make plastic products (i.e., bisphenol A (BPA), bis(2-ethylhexyl)phthalate (DEHP) and nonylphenol (NP)) in a Korean resident fish (Cyprinus carpio), crustacean (Moina macrocopa) and green alga (Pseudokirchneriella subcapitata) species was tested. It was found that M. macrocopa was particularly sensitive to those EDCs, especially DEHP and NP. We exposed M. macrocopa to DEHP (0.0012-0.1 mg/L) and NP (0.00037-0.03 mg/L), and as a result, both chemicals significantly delayed the first day of reproduction. The no observed effect concentrations (NOECs) of DEHP and NP for this endpoint were determined to be 0.0012 and 0.00037 mg/L, respectively, which are far lower than NOECs for any other freshwater species. Existing water quality criteria of various governmental agencies do not consider the toxicity of those EDCs on M. macrocopa, and thus, use of the existing criteria for the risk assessment of the Korean freshwater environment may underestimate the ecological risk. This study recommends using the water quality criteria derived in this study (0.95 μg/L for DEHP and 0.16 μg/L for NP) based on the chronic toxicity data on Korean resident species including M. macrocopa for the aquatic ecological risk assessment in Korea rather than adopting the existing water quality criteria.

Early-life exposure to 17β-estradiol and 4-nonylphenol impacts the growth hormone/insulin-like growth-factor system and estrogen receptors in Mozambique tilapia, Oreochromis mossambicus

It is widely recognized that endocrine disrupting chemicals (EDCs) released into the environment through anthropogenic activities can have short-term impacts on physiological and behavioral processes and/or sustained or delayed long-term developmental effects on aquatic organisms. While numerous studies have characterized the effects of EDCs on temperate fishes, less is known on the effects of EDCs on the growth and reproductive physiology of tropical species. To determine the long-term effects of early-life exposure to common estrogenic chemicals, we exposed Mozambique tilapia (Oreochromis mossambicus) yolk-sac fry to 17β-estradiol (E2) and nonylphenol (NP) and subsequently characterized the expression of genes involved in growth and reproduction in adults. Fry were exposed to waterborne E2 (0.1 and 1 μg/L) and NP (10 and 100 μg/L) for 21 days. After the exposure period, juveniles were reared for an additional 112 days until males were sampled. Gonadosomatic index was elevated in fish exposed to E2 (0.1 μg/L) while hepatosomatic index was decreased by exposure to NP (100 μg/L). Exposure to E2 (0.1 μg/L) induced hepatic growth hormone receptor (ghr) mRNA expression. The high concentration of E2 (1 μg/L), and both concentrations of NP, increased hepatic insulin-like growth-factor 1 (igf1) expression; E2 and NP did not affect hepatic igf2 and pituitary growth hormone (gh) levels. Both E2 (1 μg/L) and NP (10 μg/L) induced hepatic igf binding protein 1b (igfbp1b) levels while only NP (100 μg/L) induced hepatic igfbp2b levels. By contrast, hepatic igfbp6b was reduced in fish exposed to E2 (1 μg/L). There were no effects of E2 or NP on hepatic igfbp4 and igfbp5a expression. Although the expression of three vitellogenin transcripts was not affected, E2 and NP stimulated hepatic estrogen receptor (erα and erβ) mRNA expression. We conclude that tilapia exposed to E2 and NP as yolk-sac fry exhibit subsequent changes in the endocrine systems that control growth and reproduction during later life stages.

Removal and biotransformation of 4-nonylphenol by Arthrospira maxima and Chlorella vulgaris consortium

4-Nonylphenol (4-NP) is an anthropogenic contaminant found in different environmental matrices that has an effect over the biotic and abiotic factors within the environment. Bioremediation by microorganisms can be used as a potential treatment to remove this pollutant. In this work, a consortium of two microorganisms, Arthrospira maxima and Chlorella vulgaris, was employed to remove 4-NP from water. The parameters analyzed included cell growth, removal of 4-NP, and 4-NP remnant in the biomass. In addition, the metabolites produced in the process by this consortium were identified. It was found that C. vulgaris is more resistant to 4-NP than A. maxima (cell growth inhibition by 4-NP of 99%). The consortium used in this study had an IC₅₀ greater than any strain of microalgae or cyanobacteria reported for 4-NP removal (9.29 mg/L) and reduced up to 96% of 4-NP in water in the first 48 h of culture. It was also observed that there is a bio-transformation of 4-NP, comparable with the process carried out by another bacterium, in which three similar metabolites were found (4-(1-methyl-octyl)-4-hydroxy-cyclohex-2-enone, 4-nonyl-4-hydroxy-ciclohexa-2,5-dienone and 4-nonyl-4-hydroxy- ciclohex-2-enone) and one that is similar to plant metabolism (4-nonyl-(1-methyl,6,8-metoxy)-hydroxybenzene). These results indicate that microalgae and cyanobacteria consortium can be used to remove 4-NP from water.

Systems analysis of the liver transcriptome in adult male zebrafish exposed to the non-ionic surfactant nonylphenol

Nonylphenol (NP) arises from the environmental degradation of nonylphenol ethoxylates. It is a ubiquitous environmental contaminant and has been detected at levels up to 167 nM in rivers in the United States. NP is an endocrine disruptor (ED) that can act as an agonist for estrogen receptors. The Adverse Outcome Pathway (AOP) framework defines an adverse outcome as the causal result of a series of molecular initiating events (MIEs) and key events (KEs) that lead to altered phenotypes. This study examined the liver transcriptome after a 21 day exposure to NP and 17β-estradiol (E2) by exploiting the zebrafish (Danio rerio) as a systems toxicology model. The goal of this study was to tease out non-estrogenic genomic signatures associated with NP exposure using DNA microarray and RNA sequencing. Our experimental design included E2 as a positive and potent estrogenic control in order to effectively compare and contrast the 2 compounds. This approach allowed us to identify hepatic transcriptomic perturbations that could serve as MIEs for adverse health outcomes in response to NP. Our results revealed that exposure to NP was associated with differential expression (DE) of genes associated with the development of steatosis, disruption of metabolism, altered immune response, and metabolism of reactive oxygen species, further highlighting NP as a chemical of emerging concern (CEC).

Effects of long-term 4-nonylphenol dietary exposure on reproductive ability of Japanese quails (Coturnix japonica)

As an endocrine disruptor, 4-nonylphenol (4-NP) is widespread in the environment. Here, we investigated the effect of long-term 4-NP dietary exposure on Japanese quails (Coturnix japonica). A total of 72 quails were evenly divided into 24 cages (12 cages for the reproductive toxicity study and 12 cages for the histopathology study, with one male quail and two female quails in each cage) and fed with various doses of 4-NP in diet. The body weight in quails administered with 4-NP was significantly decreased (P < 0.05) in a time- and dose-dependent manner. The egg fertilization rate significantly decreased (P < 0.05) in all treated groups, which was 91.4%, 86.5%, 85.4%, and 86.2% in the control group, 10 mg·kg^-1, 20 mg·kg^-1, and 50 mg·kg^-1 treatment groups, respectively. Moreover, the hatching rate was also significantly decreased (P < 0.05) in the 50 mg·kg^-1 treatment group compared with the control group. Furthermore, the 14-day survival rate of young quails was significantly decreased (P < 0.05) in all treated groups, which was 98.0%, 91.1%, 89.8%, and 86.8% in the control group, 10 mg·kg^-1, 20 mg·kg^-1, and 50 mg·kg^-1 treatment groups, respectively. Damaged spermatogenesis in male quails was found in all treated groups. In conclusion, oral administration of 4-NP impaired the gonads of male quails, leading to reproduction performance damage of Japanese quails.

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 Nonylphenol-Induced Oxidative Stress in Ovary of Cichlid Fish, <i>Etroplus maculatus</i> (Bloch, 1795)

The present study was designed to evaluate the effects of nonylphenol in the pro-oxidant/ antioxidant system in ovary of the cichlid fish Etroplus maculatus. Fishes were exposed at two sublethal concentrations (one-fifth and one-tenth of LC50) of nonylphenol for 24, 72 and 96 h maintaining control groups. The oxidative stress indices as the activities of antioxidant enzymes, superoxide dismutase, catalase, glutathione reductase along with the levels of hydrogen peroxide generation and lipid peroxidation were monitored in concentration-and time-dependent manner. Activity of superoxide dismutase significantly (P<0.05) increased at both concentrations in time-dependent manner. Meanwhile the activities of catalase and glutathione reductase significantly (P<0.05) decreased after 72 and 96 h of nonylphenol treatment. The levels of hydrogen peroxide generation and lipid peroxidation increased in all treatment groups when compared to controls. The present results demonstrated that the induction of oxidative stress in ovary of fish by the generation of lipid peroxidation could be due to the exposure of environmental contaminant, nonylphenol. Therefore, the observed oxidative stress in ovary can be indicated as a mechanism of toxicity in the fish exposed to nonylphenol.

Effects of Nonylphenol-Induced Oxidative Stress in Ovary of Cichlid Fish, <i>Etroplus maculatus</i> (Bloch, 1795)

The present study was designed to evaluate the effects of nonylphenol in the pro-oxidant/ antioxidant system in ovary of the cichlid fishEtroplus maculatus. Fishes were exposed at two sublethal concentrations (one-fifth and one-tenth of LC50) of nonylphenol for 24, 72 and 96 h maintaining control groups. The oxidative stress indices as the activities of antioxidant enzymes, superoxide dismutase, catalase, glutathione reductase along with the levels of hydrogen peroxide generation and lipid peroxidation were monitored in concentration-and time-dependent manner. Activity of superoxide dismutase significantly (P<0.05) increased at both concentrations in time-dependent manner. Meanwhile the activities of catalase and glutathione reductase significantly (P<0.05) decreased after 72 and 96 h of nonylphenol treatment. The levels of hydrogen peroxide generation and lipid peroxidation increased in all treatment groups when compared to controls. The present results demonstrated that the induction of oxidative stress in ovary of fish by the generation of lipid peroxidation could be due to the exposure of environmental contaminant, nonylphenol. Therefore, the observed oxidative stress in ovary can be indicated as a mechanism of toxicity in the fish exposed to nonylphenol.

Detection of Bisphenol A and Nonylphenol in Rat's Blood Serum, Tissue and Impact on Reproductive System

Introduction

Bisphenol A (BPA) and Nonylphenol (NP) have estrogen-like activity, and some of their adverse biological effects have been demonstrated. This study was designed to determine the association of plasma and tissue concentrations of BPA and NP and changes in the parameters of the reproductive system in rats.

Methods

Male Wistar rats were administered three doses of BPA and NP (5, 25, and 125 μg/kg) by gavage for 35 consecutive days in 2014–2015, and a 2-ml blood sample was taken from each treated rat. Concentrations of BPA and NP in the blood were determined using the HPLC-fluorescence detection method. The sperm are produced in the epididymis and vas deferens, and they swim up in Ham’s F10 solution, and, then, various parameters were evaluated using an invert microscope, and they included the count, motility, and morphology of the sperm.

Results

The weight of the testes and prostate in the rats receiving BPA and NP treatment showed significant decreases compared to the control group. Similarly, NP created higher concentration than BPA in the serum (e.g., 5.48 ± 0.65 vs. 1.36 ± 0.25, at 125 μg/kg). Compared to the control group, dose-dependent significant decreases in count and motility in the sperm were observed following the administration of BPA (25 and 125 μg/kg) and NP (all three doses). Morphologic aspects of the rats’ sperm were changed in various doses of BPA and NP

Conclusions

According to our findings, BPA and NP induced dose-dependent toxic effects on various parameters, i.e., sperm toxicity, weight of the testes, and weight of the prostate gland.

Criteria for Reporting and Evaluating ecotoxicity Data (CRED): comparison and perception of the Klimisch and CRED methods for evaluating reliability and relevance of ecotoxicity studies

BACKGROUND

The regulatory evaluation of ecotoxicity studies for environmental risk and/or hazard assessment of chemicals is often performed using the method established by Klimisch and colleagues in 1997. The method was, at that time, an important step toward improved evaluation of study reliability, but lately it has been criticized for lack of detail and guidance, and for not ensuring sufficient consistency among risk assessors.

RESULTS

A new evaluation method was thus developed: Criteria for Reporting and Evaluating ecotoxicity Data (CRED). The CRED evaluation method aims at strengthening consistency and transparency of hazard and risk assessment of chemicals by providing criteria and guidance for reliability and relevance evaluation of aquatic ecotoxicity studies. A two-phased ring test was conducted to compare and characterize the differences between the CRED and Klimisch evaluation methods. A total of 75 risk assessors from 12 countries participated. Results show that the CRED evaluation method provides a more detailed and transparent evaluation of reliability and relevance than the Klimisch method. Ring test participants perceived it to be less dependent on expert judgement, more accurate and consistent, and practical regarding the use of criteria and time needed for performing an evaluation.

CONCLUSIONS

We conclude that the CRED evaluation method is a suitable replacement for the Klimisch method, and that its use may contribute to an improved harmonization of hazard and risk assessments of chemicals across different regulatory frameworks.

A purge and trap integrated microGC platform for chemical identification in aqueous samples

The majority of current micro-scale gas chromatography (μGC) systems focus on air sampling to detect volatile organic compounds (VOCs). However, purging the VOCs from a water sample using microsystems is an unchartered territory. Various organic compounds used in everyday life find their way to water bodies. Some of these water organic compounds (WOCs) persist or degrade slowly, threatening not just human existence but also aquatic life. This article reports the first micro-purge extractor (μPE) chip and its integration with a micro-scale gas chromatography (μGC) system for the extraction and analysis of water organic compounds (WOCs) from aqueous samples. The 2 cm × 3 cm μPE chip contains two inlet and outlet ports and an etched cavity sealed with a Pyrex cover. The aqueous sample is introduced from the top inlet port while a pure inert gas is supplied from the side inlet to purge WOCs from the μPE chip. The outlets are assigned for draining water from the chip and for directing purged WOCs to the micro-thermal preconcentrator (μTPC). The trapped compounds are desorbed from the μTPC by resistive heating using the on-chip heater and temperature sensor, are separated by a 2 m long, 80 μm wide, and 250 μm deep polydimethylsiloxane (OV-1) coated μGC separation column, and are identified using a micro-thermal conductivity detector (μTCD) monolithically integrated with the column. Our experiments indicate that the combined system is capable of providing rapid chromatographic separation (<1.5 min) for quaternary WOCs namely toluene, tetrachloroethylene (PCE), chlorobenzene and ethylbenzene with a minimum detection concentration of 500 parts-per-billion (ppb) in aqueous samples. The proposed method is a promising development towards the future realization of a miniaturized system for sensitive, on-site and real-time field analysis of organic contaminants in water.

Spatial distribution and migration of nonylphenol in groundwater following long-term wastewater irrigation

Seen as a solution to water shortages, wastewater reuse for crop irrigation does however poses a risk owing to the potential release of organic contaminants into soil and water. The frequency of detection (FOD), concentration, and migration of nonylphenol (NP) isomers in reclaimed water (FODRW), surface water (FODSW), and groundwater (FODGW) were investigated in a long-term wastewater irrigation area in Beijing. The FODRW, FODSW and FODGW of any or all of 12 NP isomers were 66.7% to 100%, 76.9% to 100% and 13.3% to 60%, respectively. The mean (±standard deviation) NP concentrations of the reclaimed water, surface water, and groundwater (NPRW, NPSW, NPGW, repectively) were 469.4±73.4 ng L(-1), 694.6±248.7 ng(-1) and 244.4±230.8 ng(-1), respectively. The existence of external pollution sources during water transmission and distribution resulted in NPSW exceeding NPRW. NP distribution in groundwater was related to the duration and quantity of wastewater irrigation, the sources of aquifer recharge, and was seen to decrease with increasing aquifer depth. Higher riverside infiltration rate nearby leads to higher FODGW values. The migration rate of NP isomers was classified as high, moderate or low.

In vitro effects of nonylphenol on motility, mitochondrial, acrosomal and chromatin integrity of ram and boar spermatozoa

The objective of this study was to determine the effects of nonylphenol (NP) on viability of ram and boar sperm in vitro. Ram or boar spermatozoa were exposed to 1, 10, 100, 250 and 500 μg NP ml(-1) for 1, 2, 3 or 4 h. Computer-assisted sperm motility analysis (CASA) system was used to evaluate sperm motility characteristics. Flow cytometry was used to determine mitochondrial membrane potential (MMP) and chromatin integrity, while epifluorescent microscopy was used to determine sperm acrosomal status. Exposure of both species spermatozoa to 250 and 500 μg NP ml(-1) was detrimental to progressive motility (P < 0.05), and its adverse effect was significant at lower (100 μg NP ml(-1) ) concentration (P < 0.05). The percentages of ram and boar spermatozoa with high MMP declined drastically after exposures to ≥250 μg ml(-1) NP (P < 0.05). Unlike chromatin integrity, which did not appear to be altered by NP exposure, there were dose-dependent NP effects (P < 0.05) on acrosomal integrity of both species at as low as 1 μg ml(-1) NP for boar spermatozoa and 10 μg ml(-1) NP for ram spermatozoa. These data show adverse effects of NP on ram and boar spermatozoa and thus its potential harmful effects on male reproduction as NP is found in fruits, vegetables, human milk, fish and livestock products.

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

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

Toxicity of environmental contaminants to fish spermatozoa function in vitro--a review

In vitro techniques for investigating the toxic effects of environmental contaminants (EC) on fish spermatozoa motility kinetics and fertilizing ability are valuable tools to understand toxicity mechanisms and sites of action. In vitro techniques may also be well-suited to studies of endocrine disruption in male fertility in vivo. This review shows ECs to decrease or suppress spermatozoa motility kinetics and fertilizing ability in a dose-dependent manner, with toxic concentrations being much higher than those reported in the aquatic environment. Sites of action depend on EC concentration and duration of exposure. Both instant (immediate) and incubated exposure of spermatozoa to ECs results in damage to the plasma membrane and the axoneme, while disruption of energy metabolism appears only during incubated exposure. Spermatozoa lose fertilizing ability following exposure to ECs in vitro, not only due to inhibition or suppression of the initiation of motility, but also through damage to DNA. This review highlights the significant lack of information about disruption of spermatozoa function associated with exposure to water from polluted areas as well as combined effects of ECs. Specifics of alterations in intracellular signaling cascades involved in the initiation of spermatozoa motility following exposure to sublethal concentrations of ECs remain unknown. Further studies are also needed to elucidate in vitro EC effects during spermatozoa maturation, when spermatozoa acquire the potential for motility.

Teratogenic effects of 4-nonylphenol on early embryonic and larval development of the catfish Heteropneustes fossilis

Alkylphenol polyethoxylates (APEs), which are widely used in detergents, paints, herbicides, insecticides, and in many other formulations, have been widely detected in aquatic environments. 4-Nonylphenol (NP) is an important APE detected at microgram levels per litre (0.1-336 μg/L) in water. The objective of the present study was to evaluate NP's toxic effects at low and high sublethal concentrations (0.1 and 1 μg/L) on embryonic development of the catfish Heteropneustes fossilis at different time intervals. The data show that fertilization rate was decreased and cleavage and blastula were severely affected leading to complete mortality of embryos. NP exposure resulted in various body malformations in larvae, such as vertebral deformations, e.g., fin blistering/necrosis, axial deformities (lordosis, kyphosis, and scoliosis) of the spine in the abdominal and caudal region, tail curved completely backward, shortened body, severe spinal and yolk sac malformations, C-shaped severe spinal curvature, cranial malformation with undeveloped head, and failure of eye development. The level of body malformations increased with the concentration and exposure time. After 72 h of exposure, all larvae were dead at both concentrations. Scanning electron microscope study showed that epidermal cells (keratinocytes) were severely damaged in both low- and high-dose treatments throughout development, leading to development of numerous depressions representing sinking holes on the skin. Mucous glands increased significantly in treatment groups compared with control groups. The present study highlights the severe teratogenic effects of NP. The prevalence of the contaminant, if not checked, can lead to decreased population and ultimate disappearance of the species.

Bisphenol-A affects the developmental progression and expression of heat-shock protein genes in the moth Sesamia nonagrioides

The effects of bisphenol A (BPA) on the endocrine system of vertebrates have been demonstrated in several studies. Here, we report the impact of BPA on the developmental progression and expression of heat shock protein genes on the terrestrial insect Sesamia nonagrioides (Lepidoptera: Noctuidae). S. nonagrioides 1st instar larvae were exposed until the end of 6th (last) instar to selected concentrations of BPA (1 μg/L, 10 μg/L, 100 μg/L, 1 mg/L and 10 mg/L) applied in their artificial diets. The lower doses of BPA (1-10 μg/L) were found to decrease larvae's weight while the 100 μg/L dose increased it. The higher doses of BPA were found to induce various abnormal phenotypes during 5th instar larval molting, larval-pupal transformation and metamorphosis. The developmental and metamorphosis endpoints presented here may indicate the possible impact of BPA on terrestrial insects. Additionally, 6th instar larvae were injected with several concentrations of BPA. Semi-quantitative and Real-Time PCR assays were used to identify the effects of BPA in the transcriptional regulation of five heat shock protein genes (SnoHsp19.5, SnoHsp20.8, SnoHsp70, SnoHsc70 and SnoHsp83). Application of BPA by feeding or by injection induced the synthesis of the SnoHsp19.5 and SnoHsp20.8 mRNAs. The expression levels of SnoHsp70 were not affected. In contrast, SnoHsc70 and SnoHsp83, which play a pivotal role in vertebrate sex steroid signal transduction, were elevated by BPA. Our results suggest that SnoHsp19.5, SnoHsp20.8, SnoHsp83 and SnoHsc70 genes can be modulated by BPA.

The effects of an in vitro exposure to 17β-estradiol and nonylphenol on rainbow trout (Oncorhynchus mykiss) peripheral blood leukocytes

While xenoestrogens are routinely detected in the aquatic environment, there is little understanding of the immunotoxicological consequences of exposure to these chemicals in fish, or of the mechanisms through which these effects are mediated. This study was conducted to determine if estrogen receptors (ERs) are present in fish leukocytes and to characterize the effects of 17β-estradiol (E2) and the xenoestrogen nonylphenol (NP) on immune system endpoints in rainbow trout (Oncorhynchus mykiss). Q-PCR was used to confirm that freshly isolated peripheral blood leukocytes (PBLs) express ERs. Following 96-h incubations with E2 or NP (1 nM to 10 μM), PBL ER transcription was again examined using Q-PCR and lipopolysaccharide (LPS)-stimulated proliferation was assessed using flow cytometry. While the transcription of all four forms of rainbow trout ER was unaffected by treatment with E2 or NP, transcription of ERα1 and ERα2 was down-regulated following LPS stimulation. Both E2 and NP, at concentrations of ≥100 nM and 10nM respectively, suppressed leukocyte proliferation. This first report of ERs in rainbow trout PBLs suggests a mechanism through with E2 and other xenoestrogens can modulate immune function. These results highlight the potential for xenoestrogens to impact host resistance to pathogens in wild fish populations.

In vitro assessment of reproductive toxicity on rats induced by organic contaminants of source water

The safety of drinking water attracts more and more attention these years. This study focused on the reproductive toxicity of source water in Jiangsu Province, China. The organic contaminants of source water are capable of bioaccumulating and cause health effects on human beings. The toxicological tests on Spermatogenic cells, Sertoli cells and Leydig cells of male rats showed that source water extracts can reduce testicular cells membrane integrity and depress cell viability significantly. Among these testicular cells, Leydig cells are most sensitive to organic contaminants and the testosterone secretion of Leydig cells is evidently disturbed correspondingly. The phenols in the source water may be chiefly responsible for the reproductive toxicity. These data indicated that chronic reproductive toxicity of source water cannot be overlooked and action should be taken to protect human health from the threat of organic pollution of source water.

Levels of 17beta-estradiol receptors expressed in embryonic and adult zebrafish following in vivo treatment of natural or synthetic ligands

The nuclear receptors encompass a group of regulatory proteins involved in a number of physiological processes. The estrogen receptors (ERs), of which one alpha and one beta form exist in mammals function as transcription factors in response to 17β-estradiol (E2). In zebrafish there are three gene products of estrogen receptors and they are denoted esr1 (ERalpha), esr2a (ERbeta2) and esr2b (ERbeta1). Total RNA of zebrafish early life stages (<3, 6, 12, 24, 48, 72, 96 and 120 hours post fertilization) and of adult fish (liver, intestine, eye, heart, brain, ovary, testis, gill, swim bladder and kidney) were isolated following in vivo exposures. Using specific primers for each of the three zebrafish ERs the expression levels were quantified using real time PCR methodology. It was shown that in absence of exposure all three estrogen receptors were expressed in adult fish. The levels of expression of two of these three ER genes, the esr1 and esr2a were altered in organs such as liver, intestine, brain and testis in response to ligand (E2, diethylstilbestrol or 4-nonylphenol). During embryogenesis two of the three receptor genes, esr1 and esr2b were expressed, and in presence of ligand the mRNA levels of these two genes increased. The conclusions are i) estrogen receptor genes are expressed during early development ii) altered expression of esr genes in response to ligand is dependent on the cellular context; iii) the estrogenic ligand 4-nonylphenol, a manufactured compound commonly found in sewage of water treatment plants, acts as an agonist of the estrogen receptor during development and has both agonist and antagonist properties in tissues of adult fish. This knowledge of esr gene function in development and in adult life will help to understand mechanisms of interfering mimicking endocrine chemicals in vivo.

Effects of nonylphenol on motility and subcellular elements of epididymal rat sperm

Nonylphenol (NP) is an important environmental toxicant and potential endocrine disrupting chemical. The objective of these studies was to determine the effects of NP on epididymal rat sperm in vitro. Epididymal sperm samples from Sprague-Dawley rats were incubated in 1, 10, 100, 250, and 500 microg/ml NP for 1, 2, 3, or 4h. Computer-assisted sperm analysis was used to determine motility. Epifluorescent microscopy was used to determine acrosomal status and flow cytometry was used to determine mitochondrial membrane potential (MMP) and chromatin integrity. Exposure of epididymal rat sperm to 250 or 500 microg/ml NP was highly detrimental to motility (P<0.05), with complete loss of motility observed after exposure to 500 microg/ml NP (P<0.05). The acrosomal integrity of sperm was significantly reduced with the lowest concentration (1 microg/ml) of NP, and higher concentrations resulted in a dose-dependent induction of the acrosomal reaction (P<0.05). Similarly, the percentage of sperm with high MMP declined dramatically after exposure to 100, 250, and 500 microg/ml NP (P<0.05). Duration of NP exposure did not have any effect on motility or MMP and NP did not appear to have detrimental effects on chromatin integrity (P>0.05). These results indicate that major mechanism of action of NP on rat sperm is by adversely affecting their acrosomal integrity. However, NP-induced impaired sperm motility, decreased mitochondrial membrane potential also likely to play an important role in destruction of sperm function.

Biomagnification profiles of polycyclic aromatic hydrocarbons, alkylphenols and polychlorinated biphenyls in Tokyo Bay elucidated by delta13C and delta15N isotope ratios as guides to trophic web structure

Biomagnification profiles of polycyclic aromatic hydrocarbons (PAHs), alkylphenols, and polychlorinated biphenyls (PCBs) from the innermost part of Tokyo Bay, Japan were analyzed using stable carbon (delta(13)C) and nitrogen (delta(15)N) isotope ratios as guides to trophic web structure. delta(15)N analysis indicated that all species of mollusks tested were primary consumers, while decapods and fish were secondary consumers. Higher concentrations of PCBs occurred in decapods and fish than in mollusks. In contrast, concentrations of PAHs and alkylphenols were lower in decapods and fish than in mollusks. Unlike PCBs, whose concentrations largely increased with increasing delta(15)N (i.e. increasing trophic level), all PAHs and alkylphenols analyzed followed a reverse trend. Molecular weights of PAHs are lower than those of PCBs, therefore low membrane permeability caused by large molecular size is an unlikely factor in the "biodilution" of PAHs. Organisms at higher trophic levels may rapidly metabolize PAHs or they may assimilate less of them.

Treated wastewater effluent reduces sperm motility along an osmolality gradient

Many toxic effects of treated wastewater effluent on organismal and reproductive health have been documented. However, the physicochemical environment of treated wastewater effluent frequently differs considerably from that of its receiving waters and may affect organismal function independently of toxic effects. Teleost sperm, for example, may be affected by the higher osmolality of treated wastewater, as this sperm is activated for a brief period of time following ejaculation due to the sudden decrease in osmolality of its surrounding environment. In this study, we examined the effects of treated wastewater effluent on sperm motility to test the hypothesis that the higher osmolality of effluent compared to river water will adversely affect sperm activation in a concentration-dependent relationship. Treated wastewater effluent was collected on 5 days from the outflow of the Metropolitan Wastewater Treatment Plant, St. Paul, Minnesota, and from an upstream site on the Mississippi River. Milt aliquots collected from goldfish were diluted in an isotonic extender solution and subsequently activated in either deionized water, 100%, 50%, or 10% effluent, a synthetic ion mixture, or river water. Sperm motility and velocity were assessed at 15-s intervals for 1 min using a computer assisted sperm analyzer. Significant differences in performance parameters were found only at 15 s, with sperm motility and velocity declining rapidly at later sampling times. Predictably, deionized water resulted in the greatest activation of sperm motility, while motility exhibited a concentration-dependent decline in 10%, 50%, and 100% treated wastewater effluent. Interestingly, Mississippi River water and a synthetic ion mixture with an osmolality comparable to 50% effluent both resulted in the least amount of sperm activation. However, sperm activation in river water varied between collection days during the study. River water and 100% effluent both had low sperm activation characteristics despite a 10-fold difference in osmolality between these two treatments (1 and 10 mOsmol kg(-1), respectively). Results of this study indicate a concentration-dependent decrease in sperm motility in treated wastewater effluent as well as significant fluctuations of sperm activation in Mississippi River water. This study illustrates the complexity of assessing the effects of treated wastewater effluents and the difficulty of determining appropriate reference sites for such studies.

Sensitivity of brown trout reproduction to long-term estrogenic exposure

A decline in brown trout (Salmo trutta fario) catches has been reported in Switzerland, but at present the causative factors have not been clearly identified. Estrogen-active endocrine disrupters (EEDs) have been suggested as one possible explanation, since they are widespread in the aquatic environment and often found at elevated concentrations. In the present study the effects of long-term estrogenic exposure on the reproductive capability of brown trout were investigated. Adult fish were continuously exposed to an environmentally relevant mixture of the natural estrogens estrone (E1), 17beta-estradiol (E2) and the xenoestrogen 4-nonylphenol (NP); the average measured concentrations over the entire exposure time (n=9) were 14.0 ng/l (Min 8.1 and Max 20.6) for E1, 2.1 ng/l (Min 1.3 and Max 4.1) for E2 and 111.0 ng/l (Min 106.7 and Max 115.9) for NP. A solvent control served as negative control, and up to 10-fold higher mixture concentration than the environmentally relevant concentration served as positive control. The fish were exposed for 150 days from the onset of gonadal recrudescence until sexual maturation. Plasma vitellogenin (Vtg) was significantly induced by both concentrations of the estrogenic mixture, whereas effects on growth and fertility were only observed in fish exposed to the high mixture treatment. Fertilization success and offspring hatchability in brown trout exposed to the high mixture treatment were significantly reduced to 9% and 6%, respectively. Developmental time from fertilization until hatching, the percentage of larvae with malformations and survival of larvae, however, were not affected. The results suggest that a combination of estrogen-active compounds at environmentally relevant concentrations would not adversely affect those parameters of brown trout reproductive capability measured in this study. Plasma Vtg in male brown trout appeared to be more sensitive to (xeno)estrogen exposure than the measured reproductive effects.

Xenoestrogen exposure and effects in English sole (Parophrys vetulus) from Puget Sound, WA

Vitellogenin, a yolk protein produced in the liver of oviparous animals in response to estrogens, normally occurs only in sexually mature females with developing eggs. However, males can synthesize vitellogenin when exposed to environmental estrogens, making the abnormal production of vitellogenin in male animals a useful biomarker for xenoestrogen exposure. In 1997-2001, as part of the Washington State's Puget Sound Assessment and Monitoring Program, we surveyed English sole from a number of sites for evidence of xenoestrogen exposure, using vitellogenin production in males as an indicator. Significant levels of vitellogenin were found in male fish from several urban sites, with especially high numbers of fish affected in Elliott Bay, along the Seattle Waterfront. Intersex fish were rare, comprising only two fish out of more than 2900 examined. Other ovarian and testicular lesions, including oocyte atresia, were also observed, but their prevalence did not appear to be related to xenoestrogen exposure. However, at the Elliott Bay sites where abnormal vitellogenin production was observed in male sole, the timing of spawning in both male and female English sole appeared altered. Sources of xenoestrogens and types of xenoestrogens present in Elliott Bay are poorly documented, but the compounds are likely associated with industrial discharges, surface runoff, and combined sewer outfalls.

Determination of spermatological properties of male Liza abu (Heckel, 1843) in Atatürk Dam Lake, Sanliurfa

The aim of this study was to determine the spermatological characteristics in male L. abu during the spawning season. Semen was collected weekly by abdominal massage from 26 males in March. In collected semen, volume, motility, duration of motility, concentration and pH were determined. In the L. abu sperm, volume (microl), motility (%), duration of motility (s), concentration (x10(9)/ml), and pH values were found 45.76 +/- 3.55, 54.25 +/- 2.93, 330.15 +/- 37.92, 4.27 +/- 0.40 and 7.87 +/- 0.05, respectively. A correlation was found between semen volume and semen pH. Semen volume and the duration of sperm motility were higher in the 2nd and 3rd sampling dates than in the 1st and 4th sampling dates (P < 0.05; P < 0.01, respectively). Neither sperm motility nor sperm concentration was affected by sampling dates. Major changes in semen pH were observed in the 4th sampling date (P < 0.001). The Pearson correlation test presented significant relationships with the duration of motility, semen volume, and motility. Semen pH values were significantly correlated with the sperm concentration and semen volume. Sperm concentration was inversely correlated with semen volume. Sperm motility and duration significantly correlated with total weight. Total length significantly correlated with the duration of motility and total weight. In conclusion, these characteristics represent a valuable baseline dataset for establishing a semen quality standard and provide background information that may be useful for assisted breeding programs in this species.

The accumulation of nonylphenol in a wastewater recycling process

A mathematical model was developed in this paper to describe the nonylphenol (NP) accumulation in the effluent of a wastewater recycling system. The model quantitatively presented the relationships among the NP concentrations in the raw wastewater and the system effluent, the number of wastewater recycling cycles, the water recycling ratio, the system NP removal efficiency, and the NP accumulation factor. The mathematical model was then verified through experimental modeling of a wastewater recycling process, and it was indicated that the Pearson correlation coefficient between mathematical simulation and experimental modeling results was 0.652. The study results indicated that the NP accumulation factor of a wastewater recycling system would approach a constant for large number of wastewater recycling cycles given the wastewater recycling ratio and system NP removal efficiency. The results also revealed that the NP concentration in the effluent increased with the wastewater recycling ratio given the system NP removal efficiency, and the increase of NP removal efficiency would decrease the NP accumulation in the system effluent under a given wastewater recycling ratio condition. The model was then applied to compute the maximum wastewater recycling ratio, predict reclaimed water quality and direct the design and management of sewage recycling systems in China.

Development of a novel CASA system based on open source software for characterization of zebrafish sperm motility parameters

Although computer-assisted sperm analysis (CASA) outperforms manual techniques, many investigators rely on non-automated analysis due to the high cost of commercial options. In this study, we have written and validated a free CASA software primarily for analysis of fish sperm. This software is a plugin for the free National Institutes of Health software ImageJ and is available with documentation at . That it is open source makes possible external validation, should improve quality control and enhance the comparative value of data obtained among laboratories. In addition, we have improved upon the traditional velocity straight line (VSL) algorithm, eliminating inaccurate characterization of highly curved fish sperm paths. Using this system, the motion of zebrafish (Danio rerio) sperm was characterized relative to time post-activation and the impact of acquisition conditions upon data analysis determined. There were decreases in velocity and path straightness (STR), but not linearity (LIN), relative to time. From 30 to 300 frames/s, frame rate significantly affected curvilinear velocity (VCL) and STR measurements. Sperm density in the field of view did not affect any measured parameter. There was significant inter-male variation for VCL, VSL, velocity average path (VAP), percent motility, path character (STR, LIN), and duration of motility. Furthermore, relative sperm output (a measure reflecting both semen volume and concentration) was positively correlated to percent motility. For all motion parameters measured (except duration), the average CV was < or =10%, comparable to values obtained using commercial systems.

Toxicity of nonylphenol on the cnidarian Hydra attenuata and environmental risk assessment

Alkylphenols and their derivatives, alkylphenol polyethoxylates (APEs), are synthetic chemicals of concern owing to their endocrine properties. Nonylphenol (NP) is a critical APE metabolite because of its recalcitrance to biodegradation, toxicity, and ability to bio-accumulate in aquatic organisms. Studies of NP effects in vertebrates demonstrated estrogenic disrupting properties in fish, birds, reptiles, and mammal cells in which NP displaces the natural estrogen from its receptor. Less is known on its toxicity toward invertebrates. Effects on reproduction have been reported, but toxicity on development has been poorly documented thus far. We investigated NP toxicity on survival and regeneration of the freshwater coelenterate Hydra attenuata. Hydra is known for its regenerative capacity and its sensitivity to chemical pollution. It has been used for over 20 years to screen for teratogenicity of chemicals (Johnson et al. (1982) Teratog Carcinog Mutagen 2:263-276). Our results showed that hydra appeared as one of the most sensitive species to acute and chronic toxicity of NP compared to several freshwater invertebrates. Regeneration was disrupted at NP concentrations lower than those affecting survival. Toxicity thresholds of NP for aquatic vertebrates and invertebrates are also reported and discussed in the context of environmental risk assessment and of water quality objectives recommended for surface waters in industrialized countries. NP levels have decreased during the last decade because of a voluntary agreement of surfactant producers and users. At present, concentrations of NP found in surface waters are far below 1 microg/L in Europe, but can reach several microg/L when wastewater treatment plant inefficiency occurs.

Effect of bisphenol A on maturation and quality of semen and eggs in the brown trout, Salmo trutta f. fario

In the present study male and female brown trout (Salmo trutta f. fario) were exposed to environmentally relevant concentrations of bisphenol A (1.75, 2.40, 5.00 microg l(-1)) during the late prespawning and spawning period and the effect of this contaminant on maturation, quantity and quality of semen and eggs was investigated. In males exposed to estimated BPA concentrations of 1.75 and 2.40 microg l(-1) semen quality was lower than in the control in the beginning of spawning (reduced sperm density, motility rate, and swimming velocity) and in the middle of spawning (reduced swimming velocity, at 2.40 microg l(-1) BPA also reduced sperm motility rate). Therefore, production of high quality semen was restricted to the end of the spawning season and delayed for approximately 4 weeks in comparison to the control. At BPA exposure levels of 5.00 microg l(-1) only one of eight males gave semen of low quality (reduced semen mass, motility rate, and swimming velocity). The percentage of ovulated females was similar for the control group and the groups exposed to estimated BPA concentrations of 1.75 and 2.40 microg l(-1), whereas at 5.00 microg l(-1) BPA females did not ovulate during the investigation. While brown trout of the control group ovulated between the 28 October and 12 November, brown trout exposed to estimated BPA concentrations of 1.75 microg l(-1) BPA ovulated approximately 2 weeks later and brown trout exposed to 2.40 microg l(-1) BPA approximately 3 weeks later. Therefore, the tested BPA concentrations affected the percentage of ovulated females and the time point of ovulation. No effect was observed on the quality of eggs (egg mass, percentile mass increase during hardening, egg fertility).