Vitellogenin Induction Research Articles

Induction, purification and partial characterization of vitellogenin in an Indian major carpCatla catla(Ham.)

Vitellogenin was purified from the serum of 17-β estradiol (E2)-induced juvenile Catla catla using a simple two-step purification procedure i.e. selective chemical precipitation followed by gel filtration chromatography. Purified protein migrated as single band in a native gradient PAGE which indicated the purity of the sample. The molecular weight of the native catla vitellogenin (~440 kDa) was determined using gel filtration chromatography. In SDS-PAGE under reducing conditions catla vitellogenin dissociated into three major sub units at 115 kDa, 102 kDa and 73 kDa along with a few faint bands. Confirmation of purified protein as catla vitellogenin was supported by multiple physiological evidences, e.g. absence in male as well as juvenile sera and presence in matured female fish, ability to be synthesized upon estradiol injection in immature fish and certain unique biochemical properties like high molecular weight, phospholipoglycoprotein nature of the molecule. Western blot analysis showed that polyclonal antibody raised against purified protein detected vitellogenin in the sera of catla and in a few species selected from Cyprinidae family. These antisera were used to detect vitellogenin in liver tissue of hormone-induced catla using immunohistochemistry and its applicability in other immunoassays is discussed.

Phytoestrogens genistein and daidzein affect immunity in the nematode Caenorhabditis elegans via alterations of vitellogenin expression

Phytoestrogens, such as the soy isoflavones genistein and daidzein, are suggested to beneficially affect lipid metabolism in humans and thereby contribute to healthy ageing. New evidences show that phytoestrogens might slow ageing processes also by affecting immune processes. We tested in the nematode Caenorhabditis elegans the effects of 17β-estradiol, genistein, and daidzein on resistance versus the nematode pathogen Photorhabdus luminescens with focus on vitellogenins, which are invertebrate estrogen-responsive genes that encode homologues to ApoB100 with impact on immune functions. Here, we show that the estrogen 17β-estradiol increases the resistance of C. elegans versus P. luminescens by enhancing vitellogenin-expression at the mRNA and protein level. Knockdown of single out of five functional vits by RNA-interference blunted the life-extending effects under heat-stress of 17β-estradiol, demonstrating a lack of redundancy for the vitellogenins. RNAi for nhr-14, a suggested nuclear hormone receptor for estrogens, displayed no influence on 17β-estradiol effects. The soy isoflavone genistein reduced vitellogenin-expression and also resistance versus P. luminescens whereas daidzein increased resistance versus the pathogen in a vitellogenin-dependent manner. Our studies show that induction of estrogen-responsive vitellogenin(s) by the phytoestrogen daidzein potently increases resistance of C. elegans versus pathogenic bacteria and heat whereas genistein acts in an antiestrogenic manner.

Responses of biomarkers of a standardized (Cyprinus carpio) and a native (Pimelodella laticeps) fish species after in situ exposure in a periurban zone of Luján river (Argentina)

The Luján River basin, which is located in the northwest area of the province of Buenos Aires, Argentina, receives different anthropogenic inputs before reaching the Río de la Plata estuary. The aim of this study was to assess the adverse impact of the river in the middle part of the basin. To this end, an in situ cage assay was conducted in two sites of the river (S1 and S2) near Luján city, and the responses of hepatic biomarkers of both a standardized (Cyprinus carpio) and a native (Pimelodella laticeps) species were evaluated. The biomarkers studied were the condition factor and liver somatic indices (LSI), the enzymatic activities of catalase (CAT), superoxide dismutase (SOD), and glutathione-S-transferase (GST), lipid peroxidation levels (thiobarbituric acid reactive substances, TBARS) and the induction of hepatic cytochrome P450 1A (CYP1A) and vitellogenin (Vtg) proteins. After 14 days, LSI and GST activity increased, and TBARS levels decreased in both species exposed at S1 and S2. In addition, exposure at both sites promoted an increase in SOD activity and CYP1A induction in C. carpio, while Vtg expression was observed only at S1. A shorter exposure period (7 days) caused an initial response only at S2 mediated only by CAT in P. laticeps. Finally, our results demonstrate that a 14-day period of in situ exposure in Luján River could lead to antioxidant and biotransformation processes in C. carpio and to phase II biotransformation responses in P. laticeps.

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

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

Predicted‐no‐effect concentrations for the steroid estrogens estrone, 17β‐estradiol, estriol, and 17α‐ethinylestradiol

The authors derive predicted-no-effect concentrations (PNECs) for the steroid estrogens (estrone [E1], 17β-estradiol [E2], estriol [E3], and 17α-ethinylestradiol [EE2]) appropriate for use in risk assessment of aquatic organisms. In a previous study, they developed a PNEC of 0.35 ng/L for EE2 from a species sensitivity distribution (SSD) based on all available chronic aquatic toxicity data. The present study updates that PNEC using recently published data to derive a PNEC of 0.1 ng/L for EE2. For E2, fish were the most sensitive taxa, and chronic reproductive effects were the most sensitive endpoint. Using the SSD methodology, we derived a PNEC of 2 ng/L for E2. Insufficient data were available to construct an SSD for E1 or E3. Therefore, the authors used in vivo vitellogenin (VTG) induction studies to determine the relative potency of the steroid estrogens to induce VTG. Based on the relative differences between in vivo VTG induction, they derive PNECs of 6 and 60 ng/L for E1 and E3, respectively. Thus, for long-term exposures to steroid estrogens in surface water (i.e., >60 d), the PNECs are 6, 2, 60, and 0.1 ng/L for E1, E2, E3, and EE2, respectively. Higher PNECs are recommended for short-term (i.e., a few days or weeks) exposures.

Long-term effects of a binary mixture of perfluorooctane sulfonate (PFOS) and bisphenol A (BPA) in zebrafish (Danio rerio)

Previous in vitro studies have reported the potential of perfluorooctane sulfonate (PFOS) to increase the toxicity of other compounds. Given the complex nature of mixtures of environmental pollutants in aquatic systems together with the persistent and bioaccumulative properties of PFOS, this study aimed at evaluating the long-term effects and toxicity-increasing behavior of PFOS in vivo using the zebrafish (Danio rerio). Fish were maintained in flow-through conditions and exposed to single and binary mixtures of PFOS and the endocrine disruptor bisphenol A (BPA) at nominal concentrations of 0.6, 100 and 300μg/L and 10, 200 and 400μg/L, respectively. F1 and F2 generations were evaluated from 0 to 180 days post-fertilization (dpf) and F3 generation was evaluated from 0 to 14 dpf. Survival was documented in all generations, whereas growth, fecundity, fertilization rate, histological alterations (in liver, thyroid and gonads) and vitellogenin (Vtg) induction in males were evaluated for F1 and F2 generations. Data for growth were collected at 30, 90 and 180 dpf and data for histological evaluations and Vtg induction were analyzed at 90 and 180 dpf. No significant effects on survival were seen in the F1 generation in any treatment following 180 d exposure; however, in the F2 generation, 300μg/L PFOS both alone and in combination with BPA (10, 200 and 400μg/L) induced 100% mortality within 14 dpf. PFOS (0.6 and 300μg/L) did not increase the Vtg-inducing potential of BPA (10, 200 and 400μg/L) in a binary mixture. In contrast, binary mixtures with 300μg/L PFOS suppressed the Vtg levels in F1 males at 90 dpf when compared to single BPA exposures. Whereas the lowest tested PFOS concentration (0.6μg/L) showed an estrogenic potential in terms of significant Vtg induction, Vtg levels were generally found to decrease with increasing PFOS-exposure in both F1 and F2 generations. In F1 generation, BPA-exposure was found to increase Vtg levels in a concentration-dependent manner. Histological analyses of F1 and F2 fish revealed hepatocellular vacuolization, predominantly in males, following PFOS-exposure both alone and in combination with BPA. Hepatotoxicity by PFOS might explain the suppressed Vtg response seen in PFOS-exposed F1 and F2 males. PFOS-exposed fish also showed granulomas, mainly in the liver. Given previous reports of the immunosuppressive potential of PFOS, the granulomas could be a consequence of a PFOS-induced reduction of the immune response potential. In conclusion, the hypothesis that the presence of PFOS increases the endocrine potential of BPA could not be confirmed in zebrafish. Adverse effects on liver structure and survival were only seen at concentrations well above ecologically relevant concentrations; however, the decline in survival rates following PFOS-exposure seen over generations again documents the importance of long-term studies for the investigation of persistent environmental pollutants.

Effects of a toxic cyanobacterial bloom (Planktothrix agardhii) on fish: Insights from histopathological and quantitative proteomic assessments following the oral exposure of medaka fish (Oryzias latipes)

Cyanobacterial toxic blooms often occur in freshwater lakes and constitute a potential health risk to human populations, as well as to fish and other aquatic organisms. Microcystin-LR (the cyanotoxin most commonly detected in the freshwater environment) is a potent hepatotoxin, deregulating the kinase pathway by inhibiting phosphatases 1 and 2A. Although toxicological effects have been clearly linked to the in vitro exposure of fish to purified microcystins, cyanotoxins are produced by the cyanobacteria together with numerous other potentially toxic molecules, and their overall and specific implications for the health of fish have still not been clearly established and remain puzzlingly difficult to assess.The medaka fish (Oryzias latipes) was chosen as an in vitro model for studying the effects of a cyanobacterial bloom on liver protein contents using a gel free quantitative approach, iTRAQ, in addition to pathology examinations on histological preparations. Fish were gavaged with 5μL cyanobacterial extracts (Planktothrix agardhii) from a natural bloom (La Grande Paroisse, France) containing 2.5μgequiv. MC-LR. 2h after exposure, the fish were sacrificed and livers were collected for analysis. Histological observations indicate that hepatocytes present glycogen storage loss, and cellular damages, together with immunological localization of MCs. Using a proteomic approach, 304 proteins were identified in the fish livers, 147 of them with a high degree of identification confidence. Fifteen of these proteins were statistically significantly different from those of controls (gavaged with water only). Overall, these protein regulation discrepancies clearly indicate that oxidative stress and lipid regulation had occurred in the livers of the exposed medaka fish. In contrast to previous pure microcystin-LR gavage experiments, marked induction of vitellogenin 1 protein was observed for the first time with a cyanobacterial extract. This finding was confirmed by ELISA quantification of vitellogenin liver content, suggesting that the Planktothrix bloom extract had induced the occurrence of an endocrine-disrupting effect.

Effects of Triclosan and Triclocarban, Two Ubiquitous Environmental Contaminants, on Anatomy, Physiology, and Behavior of the Fathead Minnow (Pimephales promelas)

Triclosan (TCS) and triclocarban (TCC) are two common antimicrobial agents found in many personal care products and subsequently are detected ubiquitously in wastewater effluent and receiving waters. Both compounds are of recent regulatory interest due to their omnipresence in the environment, including in humans. Although TCS and TCC have been suggested to be endocrine active, little information exists about their effects on organismal end points in development (growth, escape performance), anatomy (morphological indices, histology), physiology (vitellogenin), and behavior of exposed aquatic organisms. In this study, newly hatched fathead minnows were exposed for 12 days, and mature male and female fathead minnows (Pimephales promelas) were exposed for 21 days to environmentally realistic concentrations (nanograms per liter) of these two compounds singularly and in mixtures. At the end of the exposure, larvae were assessed for growth and predator-avoidance performance, and a subset of mature fish was assessed for plasma vitellogenin induction, expression of secondary sexual characteristics, relative size of liver and gonads, and histopathological changes to both organs. The remaining exposed mature fish were placed in breeding pairs of one male and one female minnow from the same treatment to assess their ability to defend a nest site and reproduce. Exposure to either antimicrobial compound, alone or as a mixture, caused no changes to larval fish, gonad size, or vitellogenin concentrations in mature fathead minnows. In contrast, decreased aggression was seen in adult male fathead minnows exposed to TCC (1.6 μg/l) or a mixture (560 ng/l TCS + 179 ng/l TCC and 1.6 μg/l TCS + 450 ng/l TCC). Decreased aggression would likely decrease their ability to defend and hold a nest site needed for spawning and reproduction. Substantial variability was found in the severity of observed effects within treatments, suggesting that environmentally realistic concentrations of these compounds may only affect particularly sensitive individuals.

Enhanced effects by mixtures of three estrogenic compounds at environmentally relevant levels on development of Chinese rare minnow (Gobiocypris rarus)

The combined effects of 17β-estradiol, diethylstilbestrol and nonylphenol at environmentally relevant levels were studied on development of Chinese rare minnow. No effects on hatchability of embryos, survival of larvae, body length and body weight were found in the fish exposed to the single chemicals and their mixtures. But significant vitellogenin induction and testis somatical index reduction were observed in adult males exposed to the mixtures. Meanwhile, the sex ratio of adult fish skewed to female was found in the fish exposed to high concentration of the mixture. These results revealed not only that the co-exposure of xenoestrogens can enhance the adverse effects on the development of fish, but that the adverse effects were induced by co-exposure of xenoestrogens below the threshold of similar detectable effects for single xenoestrogen. The observations in the present study highlight the potential ecological hazard posed by the coexistence of xenobiotics in the realistic aquatic environment.

PCR–ELISA detection of estrogen receptor β mRNA expression and plasma vitellogenin induction in juvenile sole (Solea solea) exposed to waterborne 4-nonylphenol

In this study, the effect of 4-nonylphenol (4NP) on reproductive axis of sole (Solea solea) has been investigated by using selected biomarkers of estrogenic effects: vitellogenin (VTG) and estrogen receptor β (ERβ) mRNA. Furthermore, an enzyme linked immunosorbent assay (ELISA) detection system of reverse transcriptase-polymerase chain reaction (RT-PCR) products for the analysis of sole ERβ mRNA expression was developed and validated. The proposed method allows large-scale analyses of different mRNAs in fast and not expensive way. Our results have demonstrated that the PCR–ELISA method developed shows high sensitivity, good reproducibility and also the potential for semi-quantitative analysis of hepatic ERβ mRNAs. Both plasma VTG level and ERβ mRNA expression were increased in tested animals following a short exposure to environmental relevant concentrations (10−6M) of 4NP, confirming the functional role of ERβ in the regulation of xenoestrogens-induced production of VTG. The methodology provided in the present study together with the preliminary results on the hepatic expression of ERβ may be useful in environmental xenoestrogens monitoring studies, using flatfish as “sentinel” species.

Assessing the Effects of Historical Exposure to Endocrine-Active Compounds on Reproductive Health and Genetic Diversity in Walleye, a Native Apex Predator, in a Large Riverine System

In this combined field and laboratory study, we assessed whether populations of native walleye in the Upper Mississippi River experienced altered genetic diversity correlated with exposure to estrogenic endocrine-active compounds (EACs). We collected fin-clips for genetic analysis from almost 600 walleye (13 sites) and subsampled 377 of these fish (6 sites) for blood and reproductive organs. Finally, we caged male fathead minnows at 5 sampling sites to confirm the presence of estrogenic EACs. Our findings indicate that male walleye in four river segments produced measurable concentrations of plasma vitellogenin (an egg-yolk protein and, when expressed in male fish, a biomarker of acute estrogenic exposure), a finding consistent with the presence of estrogenic EACs and consistent with published historical data for at least three of these study sites (Grand Rapids, St. Paul, and Lake City on Lake Pepin). Patterns of vitellogenin induction were consistent for native walleye and caged fathead minnows. No widespread occurrence of histopathological changes, such as intersex was found compared with published reports of intersex at the furthest downstream study site. To assess possible effects of estrogenic exposure on the genetic diversity of walleye populations at the study sites, we DNA-fingerprinted individual fish using 10 microsatellite loci. Genetic differences were observed between populations; however, these differences were consistent with geographic distance between populations, with the largest observed difference in genetic diversity found between fish upstream and downstream of St. Anthony Falls (and/or Lock and Dam 1 of the Mississippi River), traditionally a historical barrier to upstream fish movement. Although the persistent occurrence of endocrine disruption in wild fish populations is troubling, we did not detect degradation of reproductive organs in individual walleye or alteration in genetic diversity of walleye populations.

Biomarker responses in Atlantic cod (Gadus morhua) exposed to produced water from a North Sea oil field: Laboratory and field assessments

Biological markers of produced water (PW) exposure were studied in Atlantic cod (Gadus morhua) in both laboratory and field experiments, using authentic PW from a North Sea oil field. In the laboratory study, the PW exposure yielded significantly elevated levels of metabolites of polycyclic aromatic hydrocarbons (PAHs) and alkylphenols (APs) in bile even at the lowest exposure dose (0.125% PW). Other biomarkers (hepatic CYP1A induction and DNA adduct formation) responded at 0.25% and 0.5% PW concentrations. In the field study, bile metabolite markers and hepatic CYP1A were clearly increased in fish caged close to the PW outfall. Induction of plasma vitellogenin was not found in laboratory or field exposures, suggesting that the levels of oestrogen agonists (such as APs) might not have been sufficient to elicit induction, under the present conditions. The applicability of the biomarkers for use in water column biomonitoring programs is discussed.

Aquatic toxicity and ecological risk assessment of seven parabens: Individual and additive approach

In the present study, aquatic concentrations of seven parabens were determined in urban streams highly affected by treated or untreated domestic sewage in Tokushima and Osaka, Japan. The detected highest concentrations were 670, 207, and 163 ng l − 1 for methylparaben, n-propylparaben, and n-butylparaben, respectively in sampling sites with watershed area of no sewer system in Tokushima. Conventional acute/chronic toxicity tests were conducted using medaka ( Oryzias latipes), Daphnia magna, and Psuedokirchneriella subcapitata for four parabens, which was consistent with our previous study on three parabens, n-butylparaben, i-butylparaben, and benzylparaben. The aquatic toxicity on fish, daphnia, and algae was weaker for the parabens with a shorter alkyl chain than those with a longer alkyl chain as predicted by their hydrophobicity. Medaka vitellogenin assays and DNA microarray analysis were carried out for methylparaben and found induction of significant vitellogenin in male medaka at 630 μg l − 1 of methylparaben, while the expression levels of genes encoding proteins such as choriogenin and vitellogenin increased for concentrations at 10 μg l − 1 of methylparaben. Measured environmental concentrations (MECs) of seven parabens in Tokushima and Osaka were divided by predicted no effect concentrations (PNECs) and hazard quotient (MEC/PNEC) was determined for individual parabens. The MEC/PNEC was highest for n-propylparaben and was 0.010 followed by n-butylparaben (max. of 0.0086) and methylparaben (max. of 0.0042). The sum of the MEC/PNEC for the seven parabens was 0.0049. Equivalence factors were assigned for each paraben on the basis of the toxicity of n-butylparaben for each species, and n-butylparaben equivalence was calculated for the measured environmental concentrations. The MEC/PNEC approach was also conducted for the n-butylparaben-based equivalence values. The maximum MEC/PNEC was 0.018, which is lower than the trigger level for further detailed study such as large-scale monitoring for chronic toxicity tests including full-life cycle tests for fish.

Gene expression in caged fish as indicators of contaminants exposure in tropical karstic water bodies

Karstic areas in Yucatan are very permeable, which allows contaminants to move rapidly into the aquifer. In the present study, we evaluated gene expression of vitellogenin (VTG) and cytochrome P-450 1A (CYP1A) in caged juvenile zebrafish deployed for 15 days in 13 different water bodies, cenotes and aguadas, throughout karstic region of the Yucatan peninsula. Gene expression was evaluated using qRT-PCR. Results indicated induction of VTG in 7 water bodies with respect to reference cage. The highest relative VTG expression, about 3000 times higher than reference cage, was found in an aguada close to a cattle farm. CYP1A induction with respect to reference cage was observed in 3 water bodies, all of them located near villages or used for tourist activities. Pollutants and biomarkers of effect should be monitored in these water bodies in order to have a better understanding of the actual levels of pollutants that are present at Yucatan’s aquifer and the potential risk to human and environmental health.

Comparative responsiveness to natural and synthetic estrogens of fish species commonly used in the laboratory and field monitoring

Exposure to estrogenic chemicals discharged into the aquatic environment has been shown to induce feminization in wild freshwater fish and although fish species have been reported to differ in their susceptibility for these effects, empirical studies that directly address this hypothesis are lacking. In this study, in vitro ERα activation assays were applied in a range of fish species used widely in chemical testing (including, zebrafish, fathead minnow, medaka) and/or as environmental monitoring species (including, roach, stickleback, carp) to assess their comparative responsiveness to natural (estrone, estradiol, estriol) and synthetic (17α-ethinylestradiol (EE2), diethylstilbestrol (DES)) estrogens. In vivo exposures to EE2 via the water (nominal 2 and 10ng/L for 7 days) were also conducted for seven fish species to compare their responsiveness for hepatic vitellogenin (VTG) mRNA induction (an ER mediated response). Of the fish species tested, zebrafish ERα was found to be the most responsive and carp and stickleback ERα the least responsive to natural steroid estrogens. This was also the case for exposure to EE2 with an ERα-mediated response sensitivity order of zebrafish>medaka>roach>fathead minnow>carp>stickleback. For VTG mRNA induction in vivo, the order of species responsiveness was: rainbow trout (not tested in the ERα activation assays)>zebrafish>fathead minnow>medaka>roach>stickleback>carp. Overall, the responses to steroid estrogens in vitro via ERα compared well with those seen in vivo (VTG induction for exposure to EE2) showing in vitro screening of chemicals using fish ERα-mediated responses indicative of estrogenic responses (VTG induction) in vivo.

Single and combined effects of selected pharmaceuticals at sublethal concentrations on multiple biomarkers in Carassius auratus

In this study, the sublethal effects of caffeine, sulfamethoxazole and their mixture on goldfish (Carassius auratus) were investigated, the biomarkers including acetylcholinesterase (AChE) in brain, 7-ethoxyresorufin O-deethylase (EROD), glutathione S-transferase (GST) and superoxide dismutase (SOD) in liver and vitellogenin (VTG) in serum were determined after 1, 2, 4, and 7 days of exposure. AChE activity was significantly inhibited by caffeine (≥0.4 mg/l), sulfamethoxazole (≥0.4 mg/l) and their mixtures (≥0.048 mg/l) during all exposure periods, and obvious concentration-response and time-response relationships were obtained. EROD, GST and SOD activities were significantly increased by individual compounds and mixtures in most cases. GST induction exhibited bell-shaped concentration-response curves. Serum VTG was significantly induced by 2 mg/l of caffeine, 10 mg/l of sulfamethoxazole and the mixtures at concentrations ≥1.2 mg/l. In general, the two pharmaceuticals induced similar biological responses. The joint effect of caffeine/sulfamethoxazole was additive with regard to AChE and GST activity variation and was antagonistic with regard to EROD and SOD induction. The results indicated that multiple biomarker response method might be a useful tool for describing an integrated toxicological effect of chemicals. VTG induction suggested that caffeine and sulfamethoxazole may cause a slightly feminization effect.

Estrogen‐like response of perfluorooctyl iodide in male medaka (Oryzias latipes) based on hepatic vitellogenin induction

Using the in vivo male medaka model, we investigated the estrogen-like response of perfluorooctyl iodide (PFOI) which is a potential source of perfluorinated carboxylic acids. Using real-time quantitative polymerase chain reaction, the expression levels of related estrogenic genes including estrogenic receptor α (ERα), ERβ, vitellogenin I (VTG I), and VTG II in the livers of male medaka exposed to PFOI were analyzed. The results showed that PFOI upregulated the expression levels of the tested genes in a dose-dependent manner. VTG protein levels increased in both dose- and time-dependent manners due to PFOI exposure. The results suggested that PFOI is a potential estrogenic compound.

Effects of biologically-active chemical mixtures on fish in a wastewater-impacted urban stream

Stream flow in urban aquatic ecosystems often is maintained by water-reclamation plant (WRP) effluents that contain mixtures of natural and anthropogenic chemicals that persist through the treatment processes. In effluent-impacted streams, aquatic organisms such as fish are continuously exposed to biologically-active chemicals throughout their life cycles. The North Shore Channel of the Chicago River (Chicago, Illinois) is part of an urban ecosystem in which > 80% of the annual flow consists of effluent from the North Side WRP. In this study, multiple samplings of the effluent and stream water were conducted and fish (largemouth bass and carp) were collected on 2 occasions from the North Shore Channel. Fish also were collected once from the Outer Chicago Harbor in Lake Michigan, a reference site not impacted by WRP discharges. Over 100 organic chemicals with differing behaviors and biological effects were measured, and 23 compounds were detected in all of the water samples analyzed. The most frequently detected and highest concentration (> 100 μg/L) compounds were ethylenediaminetetraacetic acid and 4-nonylphenolmono-to-tetraethoxycarboxylic acids. Other biologically-active chemicals including bisphenol A, 4-nonylphenol, 4-nonylphenolmono-to-tetraethoxylates, 4- tert-octylphenol, and 4- tert-octylphenolmono-to-tetraethoxylates were detected at lower concentrations (< 5 μg/L). The biogenic steroidal hormones 17β-estradiol, estrone, testosterone, 4-androstene-3,17-dione, and cis-androsterone were detected at even lower concentrations (< 0.005 μg/L). There were slight differences in concentrations between the North Side WRP effluent and the North Shore Channel, indicating minimal in-stream attenuation. Fish populations are continuously exposed to mixtures of biologically-active chemicals because of the relative persistency of the chemicals with respect to stream hydraulic residence time, and the lack of a fresh water source for dilution. The majority of male fish exhibited vitellogenin induction, a physiological response consistent with exposure to estrogenic compounds. Tissue-level signs of reproductive disruption, such as ovatestis, were not observed.

Temperature and Temporal Modulated, Dose Dependent Response of Estradiol- 17β on the Induction of Vitellogenin and Choriogenin in Channa punctatus

Temperature and Temporal Modulated, Dose Dependent Response of Estradiol- 17β on the Induction of Vitellogenin and Choriogenin in Channa punctatus

Ecotoxicogenomics to Support Ecological Risk Assessment: A Case Study with Bisphenol A in Fish

Effects of bisphenol A (BPA) on ovarian transcript profiles as well as targeted end points with endocrine/reproductive relevance were examined in two fish species, fathead minnow (Pimephales promelas) and zebrafish (Danio rerio), exposed in parallel using matched experimental designs. Four days of waterborne exposure to 10 μg BPA/L caused significant vitellogenin induction in both species. However, zebrafish were less sensitive to effects on hepatic gene expression and steroid production than fathead minnow and the magnitude of vitellogenin induction was more modest (i.e., 3-fold compared to 13,000-fold in fathead minnow). The concentration-response at the ovarian transcriptome level was nonmonotonic and violated assumptions that underlie proposed methods for estimating hazard thresholds from transcriptomic results. However, the nonmonotonic profile was consistent among species and there were nominal similarities in the functions associated with the differentially expressed genes, suggesting potential activation of common pathway perturbation motifs in both species. Overall, the results provide an effective case study for considering the potential application of ecotoxicogenomics to ecological risk assessments and provide novel comparative data regarding effects of BPA in fish.