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Vitellogenin
Kinds of Vitellogenin Selected AbstractsPresence of natural and anthropogenic organic contaminants and potential fish health impacts along two river gradients in Alberta, CanadaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2010Ken M. Jeffries Abstract In the current study, 28 organic contaminants were measured, many with estrogen-like activity, in water collected from 16 sites on two rivers in the South Saskatchewan River Basin, Alberta, Canada. The compounds detected included synthetic estrogens (birth control pill compounds and hormone therapy drugs) downstream of municipal wastewater effluents and natural hormones downstream of municipal wastewater effluents and in agricultural areas. Greater concentrations of cholesterol and derivatives, phytosterols, and fecal sterols were measured at the most downstream sites, which indicates cumulative inputs of such compounds in these rivers. A native minnow (longnose dace, Rhinichthys cataractae) was sampled to assess pathophysiological responses to exposure to compounds with estrogen-like activity. Hepatic vitellogenin protein was detected in at least one adult male longnose dace from 14 of 15 sites sampled for fish. Vitellogenin was negatively correlated with hepatosomatic (r,=,,0.47, p,<,0.001) and gonadosomatic (r,=,,0.44, p,<,0.003) indices, which suggests potential health impacts in male longnose dace in the South Saskatchewan River Basin. The current study demonstrates that organic contaminants, many with estrogen-like activity, are distributed over hundreds of kilometers throughout the South Saskatchewan River Basin and not just downstream of major point-sources. Therefore, many activities within these basins impact water quality in the South Saskatchewan River Basin and affect endemic longnose dace populations. Environ. Toxicol. Chem. 2010;29:2379,2387. © 2010 SETAC [source] Dynamics of 17,-Ethynylestradiol exposure in rainbow trout (Oncorhynchus mykiss): Absorption, tissue distribution, and hepatic gene expression patternENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2006Ann D. Skillman Abstract 17,-Ethynylestradiol (EE2) is a synthetic estrogen identified in sewage effluents. To understand better the absorption kinetics of EE2 and the induction of vitellogenin (VTG) and estrogen receptor , (ER,) mRNA, we subjected male rainbow trout (Onchorynchus mykiss) to continuous water exposures of 125 ng/L of EE2 for up to 61 d. Trout were either repetitively sampled for blood plasma or serially killed at selected time intervals. Vitellogenin, ER, mRNA, and EE2 were measured using enzymelinked immunosorbent assay and using quantitative polymerase chain reaction and gas chromatography,mass spectrometry, respectively. In separate experiments, trout were exposed to EE2 for 7 d, and hepatic gene expression was assessed using a low- and high-density cDNA microarray. The EE2 was rapidly absorbed by the trout, with an apparent equilibrium at 16 h in plasma and liver. The ER, mRNA levels also increased rapidly, reaching near-peak levels by 48 h. In contrast, plasma levels of VTG continuously increased for 19 d. After 61 d, tissues with the highest levels of VTG were the liver, kidney, and testes. Microarray-based gene expression studies provided unexpected results. In some cases, known estrogen-responsive genes (e.g., ER,) were unresponsive, whereas many of the genes that have no apparent link to estrogen function or EE2 toxicity were significantly altered in expression. Of the two microarray approaches tested in the present study, the high-density array appeared to be superior because of the improved quality of the hybridization signal and the robustness of the response in terms of the number of genes identified as being EE2 responsive. [source] Dotterprotein hält Arbeiterinnen der Honigbiene jungBIOLOGIE IN UNSERER ZEIT (BIUZ), Issue 4 2006Annette Hille-Rehfeld Die Arbeiterinnen im Bienenstaat haben je nach Arbeitseinsatz eine sehr unterschiedliche Lebenserwartung. Langlebige Individuen produzieren verstärkt das Dotterprotein Vitellogenin, das vor oxidativen Schäden schützt und daher lebensverlängernd wirkt. [source] In vivo and in vitro toxicity of decabromodiphenyl ethane, a flame retardantENVIRONMENTAL TOXICOLOGY, Issue 4 2010Tarja Nakari Abstract Toxicity of a relative new flame retardant, namely decabromodiphenyl ethane (DBDPE), marketed as an alternative to decabromodiphenyl ether (BDE-209) was assessed both in vivo and in vitro using the freshly separated fish hepatocyte assay and standardized water flea and zebrafish egg-larvae tests. The fish hepatocyte assay, based on the synthesis and secretion of vitellogenin from isolated male liver cells produced a clear dose-response curve in the presence of DBDPE. DBDPE induced the induction of hepatic ethoxyresorufin-O-deethylase (EROD) activity at low test concentrations, but started to inhibit the activity at higher concentrations. Also, the induction of the hepatocyte conjugation activity, uridinediphosphoglucuronosyltransferase (UDPGT), was induced with no signs of inhibition even at the highest test concentration. The reduced EROD activity resulted in a drop in the production of vitellogenin by the cells. In vivo tests showed that DBDPE was acutely toxic to water fleas, the 48 h EC-50 value being 19 ,g/L. Moreover, DBDPE reduced the hatching rates of exposed zebra-fish eggs and raised significantly the mortality of hatched larvae. Because there is hardly any information available on the effects of DBDPE on the aquatic environments, it is crucial to obtain more data on the effects and effective concentrations of DBDPE along with its occurrence in the environment. Such data would enable reliable assessments of the risks posed by this flame retardant. © 2009 Wiley Periodicals, Inc. Environ Toxicol 25: 333,338, 2010. [source] Biomarkers for exposure to estrogenic compounds: Gene expression analysis in zebrafish (Danio rerio)ENVIRONMENTAL TOXICOLOGY, Issue 1 2008Ulf Kausch Abstract Gene expression analyses in male zebrafish (Danio rerio) were carried out using microarray technique and quantitative polymerase chain reaction. Genes responding to the exposure to 17,-estradiol, bisphenol A and genistein were identified, among them genes involved in metabolism, reproductional and developmental processes. Threshold levels of 17,-estradiol (200 ng/L), bisphenol A (2000 ,g/L), and genistein (5000 ,g/L) for the upregulation of the vtg1 gene in short-time exposures (11 days) were determined by qPCR. 14k microarrays were used to generate complete lists of genes regulated by these estrogenic compounds. For this purpose, liver samples from 10 exposed zebrafish and 10 controls were processed. In this case the expressions of 211 genes were significantly regulated by 17,-estradiol, 47 by bisphenol A and 231 by genistein. Furthermore, it is shown that fish exposed to 17,-estradiol and genistein have similarities in their gene expression patterns, whereas bisphenol A apparently affected gene expression in a different way. Only genes coding for egg-yolk precursor protein vitellogenin were found to be regulated by all three compounds, which shows that these genes are the only suitable markers for exposure to different estrogenic compounds. The regulated genes were assigned to gene ontology classes. All three estrogenic compounds regulated genes mainly involved in primary and cellular metabolism, but genistein regulated several genes involved in cell cycle-regulation and bisphenol A several genes involved in protein biosynthesis. Genistein also upregulated the expression of four eggshell proteins, which can be used as biomarkers for exposure to this chemical. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2008. [source] Seasonal evaluation of reproductive status and exposure to environmental estrogens in hornyhead turbot at the municipal wastewater outfall of Orange County, CAENVIRONMENTAL TOXICOLOGY, Issue 5 2007Xin Deng Abstract Seasonal changes in developmental stages, condition factor (CF), gonadosomatic index, and plasma vitellogenin (Vtg) concentrations in male and female hornyhead turbot were examined at the wastewater outfall (T1) of the Orange County Sanitation District, and two farfield sites T11 (7.7 km northwest of the outfall) and Dana Point (35 km south of the outfall) between February 2005 and May 2006. Fish collected from the three sites exhibited male-oriented sex ratios. With few exceptions, developmental stages, CF, and GSI of both genders and plasma Vtg concentrations of females were not significantly different in samples collected from different sites at the same sampling period. More advanced gonad developmental stages and higher plasma Vtg concentrations in females were observed in August, indicating the seasonality of the reproductive cycle for this species. Plasma Vtg concentrations in males were observed in all of the sampling sites with the highest prevalence at T11 relative to T1 and Dana Point. The Vtg expression in males from the three sampling sites indicated widespread exposure to estrogenic compounds in waters of coastal California. However, the histopathological and reproductive relevance of the responses appeared to be insignificant and may not affect the population in these locations. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 464,471, 2007. [source] Xenoestrogenic effects of ethinylestradiol in zebrafish (Danio rerio)ENVIRONMENTAL TOXICOLOGY, Issue 3 2004Bram J. Versonnen Abstract To assess the estrogenic effects of ethinylestradiol on zebrafish, zebrafish at different developmental stages (embryos, juveniles, and adults) were exposed to the synthetic hormone ethinylestradiol (EE2) in concentrations of 1, 10, and 100 ng/L for up to 33 days. Survival, hatching, length, weight, growth, condition, hepatosomatic index, gonadosomatic index, and vitellogenin (VTG) production were examined. Exposure of zebrafish juveniles and embryos to 100 ng EE2/L for up to 33 days had significant effects on survival, growth, and hatching. Two VTG fragments with molecular weights of approximately 140 and 170 kDa were detected with protein electrophoresis and Western blotting in the blood of exposed males and exposed and unexposed females, as well as in whole-body homogenates of exposed and unexposed juveniles. Significantly higher VTG concentrations (compared to controls) were measured in adults exposed to 10 and 100 ng EE2/L for 14 days, but not in fish exposed to 1 ng EE2/L. This study demonstrated that (1) zebrafish juveniles, larvae, and embryos are sensitive to the toxic effects of the endocrine disrupter EE2; (2) the effects on VTG production in adults are detected after exposure to environmentally relevant concentrations of EE2; (3) unexposed juvenile zebrafish produce measurable concentrations of VTG. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 198,206, 2004. [source] Exposure of three generations of the estuarine sheepshead minnow (Cyprinodon variegatus) to the androgen, 17,-trenbolone: Effects on survival, development, and reproductionENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2010Geraldine M. Cripe Abstract Estimating long-term effects of endocrine-disrupting chemicals on a species is important to assessing the overall risk to the populations. The present study reports the results of a 42-week exposure of estuarine sheepshead minnows (Cyprinodon variegatus) to the androgen, 17,-trenbolone (Tb) conducted to determine if partial-(F0) or single-generation (F1) fish exposures identify multigenerational (F0,F3) effects of androgens on fish. Adult F0 fish were exposed to 0.007, 0.027, 0.13, 0.87,and 4.1,µg Tb/L, the F1 generation to ,0.87,µg Tb/L, the F2 fish to ,0.13,µg Tb/L, and the F3 fish to ,0.027,µg Tb/L. The highest concentrations with reproducing populations at the end of the F0, F1, and F2 generations were 4.1, 0.87, and 0.027,µg Tb/L, respectively. Reproduction in the F0, F1, and F2 generations was significantly reduced at 0.87, 0.027, and 0.027,µg Tb/L, respectively. Fish were significantly masculinized in the F1 generation exposed to 0.13 µg Tb/L or greater. Female plasma vitellogenin was significantly reduced in F0 fish exposed to ,0.87,µg Tb/L. Gonadosomatic indices of the F0 and F1 generations were significantly increased at 0.87 and 0.13 µg Tb/L in the F0 and F1 generation, respectively, and were accompanied by ovarian histological changes. Reproduction was the most consistently sensitive measure of androgen effects and, after a life-cycle exposure, the daily reproductive rate predicted concentrations affecting successive generations. The present study provides evidence that a multiple generation exposure of fish to some endocrine-disrupting chemicals can result in developmental and reproductive changes that have a much greater impact on the success of a species than was indicated from shorter term exposures. Environ. Toxicol. Chem. 2010;29:2079,2087. © 2010 SETAC [source] Pulp and paper mill effluents induce distinct gene expression changes linked to androgenic and estrogenic responses in the fathead minnow (Pimephales promelas)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2010Julieta Werner Abstract Although effluent treatment systems within pulp and paper mills remove many toxicants and improve wastewater quality, there is a need to understand and quantify the effectiveness of the treatment process. At a combined news and kraft pulp and paper mill in northwestern Ontario, Canada, fathead minnow (FHM) reproduction and physiology were examined before, during, and after a short-term (6-d) exposure to 10% (v/v) untreated kraft mill effluent (UTK), 25% (v/v) secondary treated kraft mill effluent (TK), and 100% (v/v) combined mill outfall (CMO). Although UTK exposure significantly decreased egg production, neither TK nor CMO caused any reproductive changes. The expression of six genes responsive to endocrine-disrupting compounds, stress, or metals was then examined in livers of these fish using real-time polymerase chain reaction. In female FHMs, none of the three effluents induced significant expression changes in any genes investigated. By contrast, in males there were significant increases in the mRNA levels of androgen receptor, estrogen receptor (ER) ,, and cytochrome P4501A (CYP1A) upon UTK and TK exposure but no changes in ER, or vitellogenin (VTG) gene expression, whereas CMO exposure significantly increased the mRNA levels of ER,, VTG, and CYP1A. Together, these results suggest that kraft effluent before and after biological treatment contained compounds able to induce androgenic effects in FHMs, and that combination of kraft and newsmill effluents eliminated the androgenic compounds while inducing distinct and significant patterns of gene expression changes that were likely due to estrogenic compounds produced by the newsmill. Environ. Toxicol. Chem. 2010;29:430,439. © 2009 SETAC [source] Agrichemicals in nebraska, USA, watersheds: Occurrence and endocrine effectsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2009Marlo K. Sellin Abstract The objective of the present study was to determine the occurrence and endocrine effects of agrichemicals in four Nebraska, USA, watersheds,the Elkhorn, Platte, Niobrara, and Dismal rivers. Land use in the Elkhorn River and Platte River watersheds is characterized by intense agriculture, including row crop and beef cattle production. In contrast, land within the Niobrara River and Dismal River watersheds consists primarily of grasslands. Polar organic chemical integrative samplers (POCIS) and caged fathead minnows were deployed at a site within each watershed for 7 d. The POCIS were analyzed for pesticides and hormones, while the caged minnows were analyzed for the expression of estrogen- and androgen-responsive genes. Amounts of pesticides recovered in POCIS extracts from the Elkhorn and Platte rivers were higher than those recovered from the Niobrara and Dismal rivers. Furthermore, female minnows deployed in the Elkhorn River experienced significant reductions in expression of two estrogen-responsive genes (vitellogenin and estrogen receptor ,) relative to females deployed at the other sites, indicating alterations in endocrine function. However, the defeminization of these females could not be definitely linked to any of the agrichemicals detected in the POCIS recovered from the Elkhorn River. [source] Time-Dependent transcriptional profiles of genes of the hypothalamic-pituitary-gonadal axis in medaka (Oryzias latipes) exposed to fadrozole and 17,-trenboloneENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2008Xiaowei Zhang Abstract Both the anabolic androgen 17,-trenbolone (TRB) and the aromatase inhibitor fadrozole (FAD) can cause decreased plasma concentrations of estrogen (E2) and reduce fecundity of fish. However, the underlying mechanisms and the molecular pathways involved are largely unknown. The present study was designed to assess time-dependent effects of FAD and TRB on the transcriptional responses of the hypothalamic-pituitary-gonadal (HPG) axis of Japanese medaka (Oryzias latipes). Fourteen-week-old Japanese medaka were exposed to 50 ,g FAD/L or 2 ,g TRB/L in a 7-d static renewal test, and the expression profiles of 36 HPG axis genes were measured by means of a medaka HPG real-time reverse-transcription polymerase chain reaction array after 8 h, 32 h, or 7 d of exposure. Exposure to TRB or FAD caused lesser fecundity of Japanese medaka and down-regulated transcription of vitellogenin and choriogenin (CHG) gene expression in the liver of females. Exposure to FAD for 8 h resulted in an 8-fold and 71-fold down-regulation of expression of estrogen receptor , and choriogenin L (CHG L), respectively, in female liver. 17,-Trenbolone caused similar down-regulation of these genes, but the effects were not observed until 32 h of exposure. These results support the hypothesis that FAD reduces plasma E2 more quickly by inhibiting aromatase enzyme activity than does TRB, which inhibits the production of the E2 precursor testosterone. Exposure to FAD and TRB resulted in rapid (after 8 h) down-regulation of luteinizing hormone receptor and low-density-lipoprotein receptor in the testis to compensate for excessive androgen levels. Overall, the molecular responses observed in the present study differentiate the mechanisms of the reduced fecundity by TRB and FAD. [source] Estrogenic effects of polychlorinated biphenyls and relation to cytochrome P4501A activity in the endangered goodeid fish Ameca splendens,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2008Armando Vega-López Abstract The present study examines the relationships between cytochrome P4501A (CYP1A) activity and vitellogenin (VTG) induction in Ameca splendens elicited by a polychlorinated biphenyl (PCB) mixture. Ethoxyresorufin- O -deethylase (EROD) activity, mRNA levels of VTG, and VTG induction were evaluated in male and female fish exposed for 1, 2, 4, 8, and 16 d to a commercial PCB mixture. Polychlorinated biphenyls induced higher EROD in both sexes and this induction was higher in females than in males. Maximum EROD and VTG induction occurred on day 1 in females, while in males these maxima occurred on days 8 and 16. A correlation between EROD and VTG induction was found only in males (p < 0.001), and VTG induction was also higher in males than in females (p < 0.01). Exposure to PCBs elicited increases in VTG expression and induction over time in males, while in females these decreased at the end of the exposure period. Deficiencies in the feedback mechanisms of male A. splendens exposed in the wild to xenoestrogens such as PCBs have probably contributed to alter the sex ratio of wild populations of this species. [source] Interaction of stilbene compounds with human and rainbow trout estrogen receptorsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2008Denina Bobbie Dawn Simmons Abstract Compounds with stilbene structures are widely used as pharmaceuticals and personal care products (PPCPs) and are present in plants. A suite of stilbene-related compounds, including PPCPs and plant-derived compounds were tested in vitro for interactions with the human and rainbow trout estrogen receptors and in vivo with rainbow trout using vitellogenin levels as a biomarker. Among the compounds with antagonistic activity, the common structural similarity was (in addition to the stilbene backbone) the presence of 4-hydroxy substitution. Stilbene-related compounds found to act as inhibitors at the estrogen receptor included the plant-derived compound resveratrol and two formulations of fluorescent whitening agents used in detergents, 4,4,-bis(2-sulfostyryl)biphenyl and diaminostilbene-1. In the yeast estrogenicity screening assay, the concentrations which caused a 50% inhibition in estrogenic response (IC50s) with the human estrogen receptor ranged from 2.56 × 10,6 to 2.56 × 10,6 M. In the rainbow trout estrogen receptor assay, the IC50s ranged from 7.75 × 10,8 to 1.11 × 10,5 M. However, in the in vivo rainbow trout vitellogenin assay, tamoxifen was the only stilbene of the compounds tested to have a significant effect as an inhibitor of estrogenicity. [source] Aqueous exposure to 4-nonylphenol and 17,-estradiol increases stress sensitivity and disrupts ion regulatory ability of juvenile Atlantic salmonENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2007Darren T. Lerner Abstract Population declines of wild Atlantic salmon have been attributed to an array of anthropogenic disturbances, including dams, commercial and recreational fishing, habitat loss, and pollution. Environmental contaminants in particular, can act as environmental stressors on fish, typically causing disruption of ion homeostasis due to their close association with the aquatic environment. To examine the effects of the xenoestrogen 4-nonylphenol (NP) or 17,-estradiol (E2) on stress sensitivity and ion regulation, we exposed juvenile Atlantic salmon continuously for 21 d to either 10 or 100 ,g/L NP (NP-L or NP-H), 2 ,g/L E2 (positive control), or vehicle control during the parr-smolt transformation in April. After treatment, fish were sampled in freshwater (FW), transferred to 30, seawater (SW) for 24 h, or subjected to a handling stress. Estradiol and NP-H increased plasma vitellogenin in males and females, and E2 increased gonadosomatic index only in males. In FW, E2 reduced sodium potassium,activated adenosine triphosphatase activity as well as plasma levels of growth hormone, insulin-like growth factor I, and triiodothyronine. Both E2 and NP-H reduced plasma sodium in FW and increased plasma chloride in SW. Plasma Cortisol levels pre- and poststressor were significantly elevated by all treatments relative to controls, but only E2 increased plasma glucose before and after the stressor. These results indicate that exposure of anadromous salmonids to environmental estrogens heightens sensitivity to external stressors, impairs ion regulation in both FW and SW, and disrupts endocrine pathways critical for smolt development. [source] Effects of the estrogen agonist 17,-estradiol and antagonist tamoxifen in a partial life-cycle assay with zebrafish (Danio rerio)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2007Leo T. M. van der Ven Abstract A partial life-cycle assay (PLC) with zebrafish (Danio rerio) was conducted to identify endocrine-disrupting effects of 17,-estradiol (E2) and tamoxifen (TMX) as reference for estrogen agonist and antagonist activity. Adult zebrafish were exposed for 21 d and offspring for another 42 d, allowing differentiation of gonads in control animals. The assessed end points included reproductive variables (egg production, fertilization, and hatching), gonad differentiation of juveniles, histopathology, and vitellogenin (VTG) expression. With E2, the most sensitive end points were feminization of offspring (at 0.1 nM) and increased VTG production in males (at 0.32 nM). At 1 nM, decreased F1 survival, increased F1 body length and weight, VTG-related edema and kidney lesions, and inhibited spermatogenesis were observed. Oocyte atresia occurred at even higher concentrations. Exposure to TMX resulted in specific effects at an intermediate test concentration (87 nM), including oocyte atresia with granulosa cell transformation and disturbed spermatogenesis (asynchrony within cysts). In F1, decreased hatching, survival, and body weight and length as well as decreased feminization were observed. Decreased vitellogenesis and egg production in females and clustering of Leydig cells in males occurred at higher concentrations. Toxicological profiles of estrogen agonists and antagonists are complex and specific; a valid and refined characterization of endocrine activity of field samples therefore can be obtained only by using a varied set of end points, including histology, as applied in the presented PLC. Evaluation of only a single end point can easily produce under- or overestimation of the actual hazard. [source] Dynamics of 17,-Ethynylestradiol exposure in rainbow trout (Oncorhynchus mykiss): Absorption, tissue distribution, and hepatic gene expression patternENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2006Ann D. Skillman Abstract 17,-Ethynylestradiol (EE2) is a synthetic estrogen identified in sewage effluents. To understand better the absorption kinetics of EE2 and the induction of vitellogenin (VTG) and estrogen receptor , (ER,) mRNA, we subjected male rainbow trout (Onchorynchus mykiss) to continuous water exposures of 125 ng/L of EE2 for up to 61 d. Trout were either repetitively sampled for blood plasma or serially killed at selected time intervals. Vitellogenin, ER, mRNA, and EE2 were measured using enzymelinked immunosorbent assay and using quantitative polymerase chain reaction and gas chromatography,mass spectrometry, respectively. In separate experiments, trout were exposed to EE2 for 7 d, and hepatic gene expression was assessed using a low- and high-density cDNA microarray. The EE2 was rapidly absorbed by the trout, with an apparent equilibrium at 16 h in plasma and liver. The ER, mRNA levels also increased rapidly, reaching near-peak levels by 48 h. In contrast, plasma levels of VTG continuously increased for 19 d. After 61 d, tissues with the highest levels of VTG were the liver, kidney, and testes. Microarray-based gene expression studies provided unexpected results. In some cases, known estrogen-responsive genes (e.g., ER,) were unresponsive, whereas many of the genes that have no apparent link to estrogen function or EE2 toxicity were significantly altered in expression. Of the two microarray approaches tested in the present study, the high-density array appeared to be superior because of the improved quality of the hybridization signal and the robustness of the response in terms of the number of genes identified as being EE2 responsive. [source] Comparison of response to 17,-estradiol and 17,-trenbolone among three small fish speciesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2006Masanori Seki Abstract Three small fish species, medaka (Oryzias latipes), fathead minnow (Pimephales promelas), and zebrafish (Danio rerio), were exposed to an estrogen, 17,-estradiol (E2), and an androgen, 17,-trenbolone (TB), for 21 d under flow-through conditions to compare the susceptibility among these three small fish species to the substances. Effects on gross morphology, including secondary sex characteristics and gonadosomatic index, as well as on blood or liver vitellogenin (VTG) levels were assessed. In E2 exposures, significant increases in estrogenic activity were observed in both sexes of all three fish species. The lowest-observedeffect concentrations (LOECs) of E2 for VTG induction in males of medaka, fathead minnow, and zebrafish were less than or equal to 8.94, 28.6, and 85.9 ng/L, respectively. In TB exposures, we observed masculinization of secondary sex characteristics in females as a result of the androgenic activity of TB in medaka with a LOEC of 365 ng/L and in fathead minnow with a LOEC of 401 ng/L. We also found VTG reduction in females of all three fish species. These results suggest that the susceptibility of medaka to estrogenic chemicals may be higher than those of fathead minnow and zebrafish and that the susceptibility of medaka to androgenic chemicals may be almost equal to that of fathead minnow in the 21-d fish assay. [source] Evaluation of the methoxytriazine herbicide prometon using a short-term fathead minnow reproduction test and a suite of in vitro bioassaysENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2006Daniel L. Villeneuve Abstract Prometon is one of the most consistently detected herbicides in the U.S. environment. However, no previous assessment of the potential for prometon or related methoxytriazine herbicides to act as endocrine-disrupting chemicals has been conducted. This study used an array of in vitro bioassays to assess whether prometon, atraton, terbumeton, or secbumeton might act as potent (ant)agonists of the aryl hydrocarbon, estrogen, androgen, or glucocorticoid receptors or as aromatase inhibitors or inducers in vitro. Potential effects of prometon were also evaluated using a 21-d fathead minnow reproduction assay. Concentrations of methoxytriazines, as great as 1 mg/L (4.4 ,M), did not induce significant dioxin-like responses in H4IIE-luc cells, estrogenic responses in MVLN cells, or androgen or glucocorticoid receptor,mediated responses in MDA-kb2 cells, nor did the methoxytriazines significantly affect aromatase activity in vitro. In the fathead minnow assay, exposure to 20, 200, or 1,000 ,g prometon/L significantly reduced the weight of the male fat pad (an androgen-responsive tissue) relative to body weight. Exposure to 20 ,g prometon/L significantly increased female plasma testosterone concentrations, but the effect was not observed at greater concentrations. Overall, prometon did not significantly reduce fecundity over the 21-d exposure, nor were other endpoints, including plasma vitellogenin and estradiol concentrations, brain and ovary aromatase activity, and male tubercle index, significantly affected. Evidence from our work suggests that prometon may cause subtle endocrine and/or reproductive effects in fathead minnows, but no clear mechanism of action was observed. The relevance of these effects to hazard assessment for the pesticide is uncertain. [source] Biochemical and histopathological effects in pearl dace (Margariscus margarita) chronically exposed to a synthetic estrogen in a whole lake experimentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2006Vince P. Palace Abstract Potential effects of exposure to the synthetic estrogen 17,-ethynylestradiol (EE2) were examined in several species of fish from a lake experimentally treated with environmentally relevant concentrations of the contaminant. Ethynylestradiol was added to Lake 260, a small Precambrian shield lake at the Experimental Lakes Area in northwestern Ontario, Canada, from May to October of 2001, 2002, and 2003. Mean concentrations of EE2 in epilimnetic waters ranged between 4.5 and 8.1 ng/L during the three years, with overall means of 6.1 (±2.8), 5.0 (±1.8), and 4.8 (±1.0) ng/L for the three years, respectively. Male and female pearl dace (Margariscus margarita) captured after EE2 additions began contained up to 4,000-fold higher concentrations of the egg yolk precursor vitellogenin than fish captured from the same lake before the EE2 additions or when compared to fish from reference lakes. Edema in the ovaries, inhibited development of testicular tissue, intersex, and histopathological kidney lesions were all evident in fish exposed to EE2. Some indications that EE2 exposure affected in vitro steroidogenic capacity of the ovaries and the testes existed, although results were not always consistent between years. Pearl dace abundance was similar in the lake treated with EE2 and the reference lake. A trend exists toward a reduced overall population of pearl dace from the treated and reference lakes, as do indications that young-of-the-year size classes are less abundant in the EE2-treated lake. Biochemical and histopathological impacts observed in fish exposed to EE2 in this study have not yet been linked to clear population level impacts in pearl dace. Monitoring of these populations is ongoing. [source] Estrogenic endpoints in fish early life-stage tests: Luciferase and vitellogenin induction in estrogen-responsive transgenic zebrafishENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2006Rinus Bogers Abstract This study incorporated specific endpoints for estrogenic activity in the early life-stage (ELS) test, as described in Guideline 210 of the Organization for Economic Cooperation and Development and traditionally used for toxicity screening of chemicals. A transgenic zebrafish model expressing an estrogen receptor,mediated luciferase reporter gene was exposed to ethi-nylestradiol (EE2), and luciferase activity as well as vitellogenin (VTG) was measured. Concentrations of EE2 were tested at 1, 3, or 10 ng/L for 30 d from fertilization or during only the last 4 d with dimethylsulfoxide (DMSO) as presolvent (0.01%). Exposure to EE2 induced no toxic effects. Mean body weights were significantly higher in groups exposed for 30 d in the presence of DMSO, but condition factors were not affected. Significant luciferase and VTG induction occurred following 30-d exposure (3 and 10 ng EE2/L), while only VTG levels were affected in the 4-d exposure (10 ng EE2/L). This study demonstrated the usefulness of incorporating estrogenic endpoints in the OECD ELS test, fitting the requirements for screening estrogenic activity of chemicals. Quantitative measurement of both VTG and luciferase activity proved to be rapid and sensitive. Additional value of using transgenic zebrafish lies in combining VTG measurement with the more mechanistic approach of luciferase induction in one experiment. [source] Reduced nicotinamide adenine dinucleotide phosphate and the higher incidence of pollution-induced liver cancer in female flounderENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2003Angela Koehler Abstract In biological effect monitoring programs, induction of biotransformation and detoxification enzymes is used as a biomarker for pollution. Yet sex differences are usually neglected in the availability of reduction equivalents needed in these metabolic pathways and may affect biomarker responses. For example, female flounder have a threefold higher incidence of macroscopic liver nodules than males of the same age class in polluted environments of the North Sea that progress toward carcinomas, whereas tumors in males virtually never develop into cancer. Evidence is presented in this review that NADPH plays a significant role in this sex-related response to xenobiotics in liver of flounder. The NADPH is needed for biosynthesis, particularly of lipids and lipoproteins, and detoxification processes such as one-electron and two-electron biotransformation and conjugation and, therefore, its availability as substrate determines biomarker responses. Biotransformation of xenobiotics is more strongly induced and conjugation processes are less affected in male flounder liver during exposure. In female liver, NADPH is required for production of the yolk precursor protein vitellogenin for oocyte production. The latter process has a higher priority than the NADPH-requiring detoxification processes because reproductive success is more relevant in evolutionary perspectives than the survival of the individual female. The data reviewed here suggest that these sex-related differences in NADPH metabolism are a major cause of the higher incidence of liver cancer in female flounder in polluted environments. [source] Effects of 4-nonylphenol and 4- tert -octylphenol on sex differentiation and vitellogenin induction in medaka (Oryzias latipes)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2003Masanori Seki Abstract Medaka (Oryzias latipes) were continuously exposed to various concentrations of two alkylphenols, 4-nonylphenol (NP) and 4- tert -octylphenol (OP), from fertilized eggs to 60 d posthatch. The effects on sexual differentiation and hepatic vitellogenin (VTG) induction in medaka were assessed to elucidate the lowest-observed-effect concentrations (LOECs) of NP and OP for these events during early life stages. The LOECs of NP and OP for these events were 11.6 and 11.4 ,g/L, respectively. These results suggest that NP and OP may have adverse effects at similar concentrations during early life stage in medaka. Additionally, we investigated whether the abnormal sex differentiation induced by these alkylphenols would be permanent or reversible once the medaka were returned to clean water. The appearance of the secondary sex characteristics reverted from female to male when fish were returned to clean water. However, gonadal histology showed that intersex gonads still existed, even after the fish were transferred to clean water for two months. These results suggest that the induced feminization of secondary sex characteristics in medaka exposed to alkylphenols during the stage of sexual differentiation may not always be permanent, but the gonadal alteration (testisova) may continue much longer. [source] Effects of the androgenic growth promoter 17-,-trenbolone on fecundity and reproductive endocrinology of the fathead minnow,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2003Gerald T. Ankley Abstract Trenbolone acetate is a synthetic steroid that is extensively used in the United States as a growth promoter in beef cattle. The acetate is administered to livestock via slow-release implants; some is converted by the animal to 17-,-trenbolone, a relatively potent androgen receptor agonist in mammalian systems. Recent studies indicate that excreted 17-,-trenbolone is comparatively stable in animal waste, suggesting the potential for exposure to aquatic animals via direct discharge, runoff, or both. However, little is known concerning the toxicity of trenbolone to fish. Our goal was to assess the effects of 17-,-trenbolone on reproductive endocrinology of the fathead minnow (Pimephales promelas). An in vitro competitive binding study with the fathead minnow androgen receptor demonstrated that 17-,-trenbolone had a higher affinity for the receptor than that of the endogenous ligand, testosterone. Male and female fish were exposed for 21 d to nominal (target) concentrations of 17-,-trenbolone ranging from 0.005 to 50 ,g/L. Fecundity of the fish was significantly reduced by exposure to measured test concentrations , 0.027 ,g/ L. The 17-,-trenbolone was clearly androgenic in vivo at these concentrations, as evidenced by the de novo production in females of dorsal (nuptial) tubercles, structures normally present only on the heads of mature males. Plasma steroid (testosterone and ,-estradiol) and vitellogenin concentrations in the females all were significantly reduced by exposure to 17-,-trenbolone. The 17-,-trenbolone also altered reproductive physiology of male fathead minnows, albeit at concentrations much higher than those producing effects in females. Males exposed to 17-,-trenbolone at 41 ,g/L (measured) exhibited decreased plasma concentrations of 11-ketotestosterone and increased concentrations of ,-estradiol and vitellogenin. Overall, our studies indicate that 17-,-trenbolone is a potent androgen and reproductive toxicant in fish. Given the widespread use of trenbolone acetate as a growth promoter, and relative stability of its metabolites in animal wastes, further studies are warranted to assess potential ecological risk. [source] The presence of morphologically intermediate papilla syndrome in United Kingdom populations of sand goby (Pomatoschistus spp.): Endocrine disruption?ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2003Mark F. Kirby Abstract The sand goby (Pomatoschistus spp.) is a small estuarine fish. Its abundance, life history, and sedentary nature lead to its adoption as a key species in the U.K. Endocrine Disruption in the Marine Environment (EDMAR) Program. This study investigated the presence of classic markers of estrogenic exposure by determining vitellogenin (VTG) and zona radiata protein (ZRP) mRNA levels and ovotestis in estuarine-caught male gobies and investigated morphological changes in the urogenital papilla (UGP). Laboratory exposures to estrogens were also conducted to ascertain the responses of these markers. Wild-caught male fish showed no evidence of ovotestis, VTG, or ZRP mRNA induction. Laboratory exposures suggested that sensitivity of the goby to VTG/ZRP mRNA induction was similar to flounder. The UGP inspection of wild-caught specimens revealed evidence of feminization of male papillae, a condition denoted as morphologically intermediate papilla syndrome (MIPS). Morphologically intermediate papilla syndrome was more prevalent at estrogenically contaminated sites. Juvenile goby experimentally exposed to 17,-estradiol for 11 to 32 weeks exhibited signs of the MIPS condition, showing that it was inducible by estrogenic exposure and could therefore be a form of estrogenic endocrine disruption. The estuaries where the MIPS condition was most prevalent (>50% at certain sites) were the Tees, Mersey, and Clyde. The potential of the MIPS condition to significantly interfere with reproductive performance is discussed as well as its use as a monitoring tool for endocrine disruption in the estuarine environment. [source] In vitro and in vivo estrogenicity and toxicity of o -, m -, and p -dichlorobenzeneENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2003Bram J. Versonnen Abstract The estrogenicity of o -, m -, and p -dichlorobenzene (DCB) was evaluated with a yeast estrogen screen (YES) and zebrafish (Danio rerio) vitellogenin (VTG) assays. With the YES, p -DCB and m -DCB were found to be estrogenic in a concentration-responsive manner. The relative potency measured with the YES (relative to 17,-estradiol) was 2.2 × 10,7 for p -DCB and 1.04 × 10,8 for m -DCB. Following acute toxicity tests with the zebrafish, plasma VTG production was measured to examine the in vivo estrogenic activity of the three compounds after a 14-d exposure. Adult zebrafish were exposed to different concentrations of o -, m - and p -DCB, ranging from 0.1 to 32 mg/L; ethynylestradiol ([EE2]; 5 ng/L, 10 ng/L, 50 ng/L, and 100 ng/L) was used as a positive control. After exposure, blood samples were taken and protein electrophoresis was performed to determine the relative VTG content. Gonadosomatic indices (GSI) and condition factors (CF) were also calculated. Elevated VTG levels and decreased female GSIs were found in fish exposed to ,5 ng EE2/L and in fish exposed to ,10 mg p -DCB/L. Low GSIs coincided with high levels of VTG in the blood of female zebrafish. This relation was not only found in fish exposed to EE2 but also in controls and fish exposed to DCB. Therefore, a direct or indirect effect of VTG on the GSI is suggested rather than a direct toxic effect of the tested compounds on the gonads. [source] Timing of exposure to a pulp and paper effluent influences the manifestation of reproductive effects in rainbow troutENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2002Michael R. Van den Heuvel Abstract Rainbow trout were exposed to a secondary treated, thermomechanical/bleached kraft pulp and paper effluent in 12,000-L, flow-through exposure tanks at an environmental research facility located at a pulp and paper mill in Kawerau, New Zealand. Trout (age, 2+ years) were obtained from a local hatchery and exposed either to upstream river water or a nominal concentration of 12% (v/v) effluent diluted in upstream river water. Three treatment groups were used: Effluent exposure that started approximately three months before gonadal growth (eight-month total exposure), effluent exposure that started approximately halfway through gonadal development (two-month total exposure), and trout exposed to reference water alone for the total duration of the experiment. Trout were sacrificed just before spawning; exposure, growth, and reproductive endpoints were assessed during and at the termination of the experiment. Reduction in growth was observed in both sexes in the eight-month treatment group relative to the river water reference treatment group. No differences were observed in condition factor or liver size in either treatment. Females in the eightmonth exposure group also had significantly lower ovary weight. The two-month exposure group showed no differences from the reference group in growth or somatic indices. Estradiol and testosterone were reduced in blood samples taken from the eight-month exposure group by four months into the experiment as compared to the reference treatment. Steroid and vitellogenin levels in individual female trout from this treatment were significantly correlated with gonadosomatic indices (GSI) measured at the termination of the experiment. The GSI was not correlated strongly or consistently with pregnenolone, nor were any treatment-related pregnenolone differences observed, indicating that the steroid hormone reductions likely were not related to cholesterol side-chain cleavage. Male trout showed significant induction of vitellogenin and lower 11-ketotestosterone during the experiment (only the eight-month group was examined), but this did not result in any significant differences in testes development. Thus, this study has shown an impact of pulp mill effluent exposure on the reproductive physiology of female trout that appeared to be hormonally mediated. Furthermore, the effect could only be manifest when the exposure was initiated before the start of gonad development. [source] Dose,response and time course relationships for vitellogenin induction in male western fence lizards (Sceloporus occidentalis) exposed to ethinylestradiolENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2002Sandra M. Brasfield Abstract The long-term goal of this research is to develop and validate an in vivo reptile model for endocrine-mediated toxicity using fence lizards (Sceloporus spp.). One of the best defined estrogenic responses in oviparous vertebrates is induction of the yolk precursor protein, vitellogenin (Vtg). In this study, dose,response and time course relationships for Vtg induction were determined in male western fence lizards (Sceloporus occidentalis) given intraperitoneal injections of 17,-ethinylestradiol (EE2). Plasma Vtg was quantified directly with an antibody-capture enzyme-linked immunosorbent assay (ELISA) and indirectly using plasma alkalinelabile phosphate (ALP) in order to compare these two methods. Both ELISA and ALP predicted similar median effective dose (ED50 [dose causing a 50% maximal response]) values for plasma Vtg induction (0.167 mg/kg for ELISA and 0.095 mg/kg for ALP). In addition, both ELISA and ALP detected significant Vtg induction at a dose of 0.0003 mg/kg of EE2, which was the lowest dose used in our study. A decrease in body weight at the highest dose (10 mg/kg) and an increase in hepatosomatic index at the four highest doses were observed. Serial dilutions of plasma from an EE2 -exposed male revealed a high correlation between plasma Vtg and ALP determinations in this species. In conclusion, our data show that plasma ALP may be a suitable alternative for measuring plasma Vtg compared with developing a Vtg ELISA in fence lizards exposed to estrogenic compounds. [source] Biological measurement of estrogenic activity in urine and bile conjugates with the in vitro ER-CALUX reporter gene assayENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2002Juliette Legler Abstract Although estrogens are excreted as biologically inactive conjugates, they can be reconverted to an active form, possibly by bacteria. A simple method was developed to deconjugate estrogen metabolites present in human urine and fish bile back to active estrogens by enzymatic hydrolysis with ,-glucuronidase or live Escherichia coli cells. Deconjugated extracts were tested for estrogenic activity in the in vitro stable estrogen receptor,mediated chemical-activated luciferase gene expression (ER-CALUX) assay. Estrogen glucuronides in urine obtained from human males and females were effectively converted to active forms after incubation with ,-glucuronidase or E. coli. The highest estrogenic activity was found in deconjugated metabolites from urine of a pregnant woman, in which levels up to 3,000 nmol estradiol equivalents per liter of urine were found after overnight incubation of urine with E. coli. Bile sampled from male bream and flounder from various freshwater and marine locations was also deconjugated and a good correlation was found between high biliary estrogenic activity and elevated levels of xenoestrogenic activity in surface water as well as in plasma vitellogenin. Therefore, the measurement of deconjugated bile could form a useful (indirect) biomarker for internal dose of xenoestrogens in male fish. [source] Utility of a juvenile fathead minnow screening assay for detecting (anti-)estrogenic substancesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2002Grace H. Panter Abstract The European Chemical Industry's aquatic research program for endocrine disrupters includes the development of an in vivo juvenile fathead minnow (Pimephales promelas) screening assay.Working within the Organization for Economic Cooperation and Development's (OECD, Paris, France) tiered approach to endocrine disrupter evaluation in fish, the juvenile fish screening protocol was adapted from the OECD test guideline 204. Six chemicals, with different (anti-)estrogenic potencies, were used to develop the in vivo juvenile fish screening protocol: diethylstilbestrol, 17,-ethynylestradiol, genistein, methoxychlor, 4- tert -pentylphenol, and ZM189,154 (a novel pharmaceutical antiestrogen). Mixed-sex juvenile fathead minnows were exposed to individual chemicals (with chemical analyzes) and sampled after 4, 7, 14, and 21 d of exposure. Wet weight, total length, condition factor, and whole-body homogenate concentrations of vitellogenin (VTG) were determined. Estrogens and antiestrogens were detected in this screen by virtue of the VTG response (an elevation or suppression, respectively) after 14 d. The study showed that the use of VTG concentrations in mixed-sex juvenile fish provides a sensitive and robust assay for the detection of both estrogenic and antiestrogenic chemicals, with widely divergent potencies. [source] A tapeworm molecule manipulates vitellogenin expression in the beetle Tenebrio molitorINSECT MOLECULAR BIOLOGY, Issue 4 2006E. Warr Abstract Metacestodes of Hymenolepis diminuta secrete a molecule that decreases vitellogenin (Vg) synthesis in the beetle host, Tenebrio molitor. The 5608 bp T. molitor Vg cDNA represents a single-copy gene encoding a single open reading frame of 1821 amino acids with a predicted molecular mass of 206 kDa. Northern blot analysis revealed detectable levels of transcripts only in adult females. In vivo, Vg mRNA abundance was significantly higher in fat bodies from infected females compared with control females at all but the earliest time point. In vitro, Vg mRNA abundance was significantly increased in fat bodies incubated with live stage I,II parasites. The apparent conflict between increased Vg mRNA abundance and decreased Vg protein in fat bodies from infected females is discussed. [source] | ||||||||||||||||