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Physiological and biochemical perturbation in Daphnia magna following exposure to the model environmental estrogen diethylstilbes trol
Abstract
The estrogenic properties of many environmental contaminants, such as DDE and PCBs, have been associated with reproductive failure in a variety of vertebrate species. While estrogens have been measured in many invertebrate species, the function of this hormone in invertebrates is controversial. The objective of the present study was to identify possible physiological and biochemical target sites for the estrogenic effects of some xenobiotics on the freshwater crustacean Daphnia magna using the model environmental estrogen diethylstilbestrol (DES). Chronic exposure of daphnids to 0.50 mg/L DBS reduced molting frequency among first-generation juveniles and decreased fecundity of second-generation daphnids. Adult first-generation daphnids chronically exposed to DES, as well as adult daphnids acutely exposed to DES for only 48 h, were examined for steroid hormone metabolic capabilities using testosterone as the model steroid. The rate of elimination of two major hydroxylated metabolites of testosterone was significantly reduced, and elimination of glucose conjugates of testosterone was significantly elevated from exposure to 0.50 mg/L DES. These results demonstrate that multigeneration exposure of daphnids to DES results in reduced fecundity and altered steroid metabolic capabilities. Thus, some arthropods, like vertebrates, are sensitive to the effects of endocrine-disrupting chemicals.
... In crustacea, diethylstilbestrol has affected the offspring rate and the reproduction of the second generation of Daphnia magna, starting from 0.2 mg/L, as demonstrated in Brennan et al. (2006) study. It was also lethal at 1.5 mg/L and caused immobilisation with EC 50 equal to 1.55 mg/L (Baldwin et al., 1995;Brennan et al., 2006). The moulting frequency, which is linked to crustaceans' growth, has been significantly reduced, starting from 0.5 mg/L (Baldwin et al., 1995). ...
... It was also lethal at 1.5 mg/L and caused immobilisation with EC 50 equal to 1.55 mg/L (Baldwin et al., 1995;Brennan et al., 2006). The moulting frequency, which is linked to crustaceans' growth, has been significantly reduced, starting from 0.5 mg/L (Baldwin et al., 1995). Similarly, body length was decreased at 0.54 mg/L and, more specifically, in female daphnids at 3 μM (Baldwin et al., 1995;Olmstead and LeBlanc, 2000). ...
... The moulting frequency, which is linked to crustaceans' growth, has been significantly reduced, starting from 0.5 mg/L (Baldwin et al., 1995). Similarly, body length was decreased at 0.54 mg/L and, more specifically, in female daphnids at 3 μM (Baldwin et al., 1995;Olmstead and LeBlanc, 2000). Additionally, diethylstilbestrol has significantly inactivated testosterone and increased glucosyltransferase activity at 0.5 mg/L (Baldwin et al., 1995). ...
Anticancer drugs in the aquatic environment have drawn a lot of attention in the last decade. Since wastewater treatment plants proved to be inefficient to fully eliminate trace
concentrations of anticancer drugs, these compounds are continuously discharged into the aquatic environment. Subsequently, non-target organisms such as the aquatic biota are directly exposed to a variety of anticancer drugs. To understand the potential impact on the aquatic organisms, a systematic review was conducted in compliance with the PRISMA guidelines. The results acquired from the 152 included studies were analysed and sorted into four categories: the impact of each included anticancer drug, the effect of metabolites, the effect of a mixture of drugs, and risk assessment. Findings showed that risk on the aquatic biota was unlikely to occur as the concentrations needed to induce effects were much higher than those detected in the environment. However, these data were based on acute toxicity and included only basic toxicity endpoints. The concentrations that produced significant effects were much lower when tested in the long-term or in multi-generational studies. Variabilities in results were also observed, these depended on the organism tested, the assessment adopted, and the endpoints selected. In this systematic review, an overall view of the research studies was generated by which all the variability factors to be considered were reported and recommendations to guide future studies were proposed.
... Also, the allometric growth rate of D. magna can be affected by estrogenic compounds (Olmstead and LeBlanc 2000). The vertebrate estrogen agonist diethylstilboestrol (DES) was selected because it has been shown that these compounds reduce molt frequency in immature daphnids (Baldwin et al. 1995) and modify the allometry of this organism (Olmstead and LeBlanc 2000). The vertebrate androgen androstenedione (AED) was selected because it has been shown that this steroid elicits developmental toxicity in daphnids (LeBlanc 1999). ...
... These results agree with those of Olmstead and LeBlanc (2000) and Lopez et al. (2011). These effects can be explained because DES in concentrations higher than 0.2 mg L -1 on Daphnia magna reduces the time and frequency of movements, inhibits fertility, and causes metabolic alterations of the steroid capabilities (Baldwin et al. 1995;Zou and Fingerman 1997;Brennan et al. 2006). Moreover, studies have shown the interaction probability of estrogenic compounds with the receptor responsible for molting and tissue differentiation in invertebrates (ecdiesteroides) (Baldwin et al. 1995;Zou and Fingerman 1997;Dinan et al. 2001;Brennan et al. 2006). ...
... These effects can be explained because DES in concentrations higher than 0.2 mg L -1 on Daphnia magna reduces the time and frequency of movements, inhibits fertility, and causes metabolic alterations of the steroid capabilities (Baldwin et al. 1995;Zou and Fingerman 1997;Brennan et al. 2006). Moreover, studies have shown the interaction probability of estrogenic compounds with the receptor responsible for molting and tissue differentiation in invertebrates (ecdiesteroides) (Baldwin et al. 1995;Zou and Fingerman 1997;Dinan et al. 2001;Brennan et al. 2006). ...
Kraft mill effluents treated by activated sludge show a reduction in acute toxicity. However, their discharges produce hormonal effects in an aquatic ecosystem, due to the sterols metabolites as androstenedione contained in the effluents. Daphnids bioassays are a powerful approach for determining toxicity. However, there are relative sensitivities depending on the species. The main objective of this study is to determine the sensitivity of D. magna and D. obtusa when exposed to kraft mill effluents, diethylstilboestrol (DES), and androstenedione (AED). The sensitivities were tested using acute bioassay exposed to kraft pulp mill. Moreover, the allometric growth rate of both daphnids affected by DES and AED regarding time were also evaluated for a period of nine days. Variation in the ratio between body length and body width - at the abdominal cavity - over time (k index) was evaluated. Results indicated that AED and DES compounds affected the allometric growth rate of daphnids. Specifically D. magna exhibited more sensitivity when it was exposed to kraft pulp mill.
... Environmental chemicals that have been classified as EDCs, are, for the most part, compounds that interfere with the vertebrate hormone system. Strenuous effort has been made to demonstrate possible endocrine disrupting effects of such EDCs in crustaceans (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30). Although effects on growth and reproduction are often reported, most studies failed to demonstrate that endocrine mechanisms were involved. ...
... Chemical EC50 (mg·L -1 ) 1 MATC (mg·L (192), 4 (193), 5 (20), 6 (145) of cadmium, rather the amount of PDH stored in the SG was affected, putatively by inhibiting the synthesis of PDH (165). Fingerman et al. also showed that drugs that deplete monoamine levels, such as reserpine or bretylium, hamper pigment dispersion when fiddler crabs, Uca pugliator, were transferred from a white background with concentrated pigments to a black background, whereas fluoxetine enhanced pigment dispersion by increasing 5-HT-levels (179,180,219). ...
Crustaceans-and arthropods in general-exhibit many unique aspects to their physiology. These include the requirement to moult (ecdysis) in order to grow and reproduce, the ability to change color, and multiple strategies for sexual differentiation. Accordingly, the endocrine regulation of these processes involves hormones, receptors, and enzymes that differ from those utilized by vertebrates and other non-arthropod invertebrates. As a result, environmental chemicals known to disrupt endocrine processes in vertebrates are often not endocrine disruptors in crustaceans; while, chemicals that disrupt endocrine processes in crustaceans are often not endocrine disruptors in vertebrates. In this review, we present an overview of the evolution of the endocrine system of crustaceans, highlight endocrine endpoints known to be a target of disruption by chemicals, and identify other components of endocrine signaling that may prove to be targets of disruption. This review highlights that crustaceans need to be evaluated for endocrine disruption with consideration of their unique endocrine system and not with consideration of the endocrine system of vertebrates.
... Frequent molting occurs in D. magna as they develop to reproductive maturity as it is required for the organism to reach its adult body size, and required after maturity only when broods are released for reproduction (Espie and Roff, 1995;Dabrunz et al., 2011). Molting behaviors in Daphnia are largely controlled by the hormone 20-hydroxyecdyson (Baldwin et al., 1995) and its accompanying ecdysone receptor (Zhao, 2020). The UVFs utilized in this study are believed to be endocrine disrupting compounds that elicit disruptions primarily via estrogen and androgen receptor pathways (Klopčič and Dolenc, 2017;Kunz and Fent, 2006). ...
Organic ultraviolet filters (UVFs) are contaminants of concern, ubiquitously found in many aquatic environments due to their use in personal care products to protect against ultraviolet radiation. Research regarding the toxicity of UVFs such as avobenzone, octocrylene and oxybenzone indicate that these chemicals may pose a threat to invertebrate species; however, minimal long-term studies have been conducted to determine how these UVFs may affect continuously exposed populations. The present study modeled the effects of a 5-generation exposure of Daphnia magna to these UVFs at environmental concentrations. Avobenzone and octocrylene resulted in minor, transient decreases in reproduction and wet mass. Oxybenzone exposure resulted in > 40% mortality, 46% decreased reproduction, and 4-fold greater reproductive failure over the F0 and F1 generations; however, normal function was largely regained by the F2 generation. These results indicate that Daphnia are able to acclimate over long-term exposures to concentrations of 6.59 μg/L avobenzone, ∼0.6 μg/L octocrylene or 16.5 μg/L oxybenzone. This suggests that short-term studies indicating high toxicity may not accurately represent long-term outcomes in wild populations, adding additional complexity to risk assessment practices at a time when many regions are considering or implementing UVF bans in order to protect these most sensitive invertebrate species.
... In all these trials, nicotine was in the maximum concentration, whereas triclosan was in the minimum concentration. The most feasible route for D. magna to remove these pollutants is biosorption and, secondly, ingestion; in both cases, the compounds/metabolites are subsequently eliminated from the D. magna through their excretions, growth, breeding, and desorption [65][66][67]. The formation of the complex not only improved the adsorption of zeolites or montmorillonites, but also favored Daphnia magna, since their mortality does not occur at the estradiol and nicotine concentrations studied. ...
... In all these trials, nicotine was in the maximum concentration, whereas triclosan was in the minimum concentration. The most feasible route for D. magna to remove these pollutants is biosorption and, secondly, ingestion; in both cases, the compounds/metabolites are subsequently eliminated from the D. magna through their excretions, growth, breeding, and desorption [65][66][67]. The formation of the complex not only improved the adsorption of zeolites or montmorillonites, but also favored Daphnia magna, since their mortality does not occur at the estradiol and nicotine concentrations studied. ...
Among emerging pollutants, endocrine disruptors such as estradiol are of most concern. Conventional water treatment technologies are not capable of removing this compound from water. This study aims to assess a method that combines physicochemical and biological strategies to eliminate estradiol even when there are other compounds present in the water matrix. Na-montmorillonite, Ca-montmorillonite and zeolite were used to remove estradiol in a medium with sulfamethoxazole, triclosan, and nicotine using a Plackett–Burman experimental design; each treatment was followed by biological filtration with Daphnia magna. Results showed between 40 to 92% estradiol adsorption in clays; no other compounds present in the mixture were adsorbed. The most significant factors for estradiol adsorption were the presence of nicotine and triclosan which favored the adsorption, the use of Ca-montmorillonite, Zeolite, and time did not favor the adsorption of estradiol. After the physicochemical treatment, Daphnia magna was able to remove between 0–93% of the remaining estradiol. The combination of adsorption and biological filtration in optimal conditions allowed the removal of 98% of the initial estradiol concentration.
... As in the Branchiopoda cladoceran water flea, D. magna, it is known that the ecdysteroids are the only steroid family in the Malacostracans as well, and the gut has been identified as a candidate organ for ecdysteroidgenesis [150,151]. Several studies have demonstrated that vertebrate-type steroids (e.g., estrogens, testosterones, and progesterone) and their agonists (e.g., diethylstilbestrol, nonylphenol, and bisphenol A as estrogen agonists, and R-1881 as an androgen agonist) can affect the growth rate, fecundity and entire sex ratio of a population [152][153][154][155][156][157]. However, there are some inconsistencies in these results caused by different experimental procedures. ...
Mechanisms underlying sex determination and differentiation in animals are known to encompass a diverse array of molecular clues. Recent innovations in high-throughput sequencing and mass spectrometry technologies have been widely applied in non-model organisms without reference genomes. Crustaceans are no exception. They are particularly diverse among the Arthropoda and contain a wide variety of commercially important fishery species such as shrimps, lobsters and crabs (Order Decapoda), and keystone species of aquatic ecosystems such as water fleas (Order Branchiopoda). In terms of decapod sex determination and differentiation, previous approaches have attempted to elucidate their molecular components, to establish mono-sex breeding technology. Here, we overview reports describing the physiological functions of sex hormones regulating masculinization and feminization, and gene discovery by transcriptomics in decapod species. Moreover, this review summarizes the recent progresses of studies on the juvenile hormone-driven sex determination system of the branchiopod genus Daphnia, and then compares sex determination and endocrine systems between decapods and branchiopods. This review provides not only substantial insights for aquaculture research, but also the opportunity to re-organize the current and future trends of this field.
... Only one study so far suggests that the species molting process may change when exposed during 21 days to 100 nm and 2 mm polystyrene particles. [56] However, contaminants from other sources have already been shown to disrupt species change molting processes such as inhibition of the molt or growth when exposed to CeO 2 NPs, [66] synthetic estrogenic agents, [67,68] and endocrine disrupting compounds. [69] We observed that polyethylene microplastic did not cause a change in the molting process, which could be caused by ingestion or interaction of the microparticles with the body surface of the organisms, causing a rupture of the molting process, as observed when the species was exposed to TiO 2 NPs [70] and Fe 2 O 3 NPs. ...
The study presents responses of D. magna newborns exposed during 96 h to polyethylene micro-plastics (MP) of size 40-48 lm in the concentrations of 20; 40; 80; 160 and 320 mg/L. The experimental design consisted of two exposure scenarios: the first group was fed at the beginning and after 48 h (3x10 À5 cells/mL of Raphidocelis subcaptata and fermented solution) and the second group was not fed as an additional stressor. The mobility of the organisms was not significantly affected in the presence of microplastics for both exposure groups. Nevertheless, the qualitative analysis showed that neonates promptly ingested microplastics in the first 24 h of the test, independently of the treatment. Polyethylene microplastics did not influence the molting process, however, significant differences were observed between the number of molts of the exposure without feed and with feed in 24 h (p ¼ 0.0007), 48 h (p ¼ 2.4 x 10 À10), 72 h (p ¼ 3.6 x 10 À10) and 96 h (p ¼ 0.003). The final body length of D. magna also showed that the food administration model in the tests contributes to the differentiation in responses. ARTICLE HISTORY
... In addition to IGRs, molting can also be disrupted by other EDCs. For example, molting is inhibited by heavy metals (Kang et al., 1997; Moreno et al., 2003; Weis et al., 1992), polychlorinated biphenyls (PCBs) (Fingerman and Fingerman, 1977), brominated flame retardants (Wollenberger et al., 2005), benzene (Cantelmo et al., 1981), methoxychlor (Baer and Owens, 1999), and vertebrate steroid hormones (Baldwin et al., 1995; Mu and LeBlanc, 2002; Zou and Fingerman, 1997a,b). Zou and Bonvillain (2004) have used chitinase activity as an in vivo screen for moltinterfering xenobiotics. ...
... Villarroel et al. (2000) observed decreased offspring production in F1 D. magna as a result of multigenerational pesticide exposure. Bervoets et al. (1996) and Baldwin et al. (1995) both observed decreased reproduction in second-generation offspring exposed to environmental contaminants . Similar to these studies, we identified decreased reproduction in D. magna as the primary adverse response to low and high cadmium exposures based on life history assays. ...
... Incidence of hermaphroditism, delay in the settlement and metamorphosis, delay in the development to D-shape, developmental abnormalities, reduction in larval survival, and changes in the sex ratio towards females [52, 53] were found in the Pacific oyster Crassostrea gigas, which is of vital importance to the aquaculture industry. Elminius modestus and Balanus amphitrite, and the polychaete worm Dinophilus gyrociliatus have been studied545556575859606162636465. Several endocrine alterations have been found after exposure to NP at concentrations ranging from 0.1 to 100 µgL-1 (Table 2). ...
... be the pre-exposure of this second generation to chemicals during the oogenesis and embryogenesis processes. Several studies have also reported increased sensitivity and decreased fitness of the second generation of daphnids exposed to endocrine disruptors (Baldwin et al., 1995;Brennan et al., 2006;Tanaka and Nakanishi, 2002). The calculated population growth (r) also showed an increase in sensitivity between the F0 and F1 generations exposed to tamoxifen metabolites. ...
Although pharmaceutical metabolites are found in the aquatic environment, their toxicity on living organisms is poorly studied in general. Endoxifen and 4-hydroxy-tamoxifen (4OHTam) are two metabolites of the widely used anticancer drug tamoxifen for the prevention and treatment of breast cancers. Both metabolites have a high pharmacological potency in vertebrates, attributing prodrug characteristics to tamoxifen. Tamoxifen and its metabolites are body-excreted by patients, and the parent compound is found in sewage treatment plan effluents and natural waters. The toxicity of these potent metabolites on non-target aquatic species is unknown, which forces environmental risk assessors to predict their toxicity on aquatic species using knowledge on the parent compounds. Therefore, the aim of this study was to assess the sensitivity of two generations of the freshwater microcrustacean Daphnia pulex towards 4OHTam and endoxifen. Two chronic tests of 4OHTam and endoxifen were run in parallel and several endpoints were assessed. The results show that the metabolites 4OHTam and endoxifen induced reproductive and survival effects. For both metabolites, the sensitivity of D. pulex increased in the second generation. The intrinsic rate of natural increase (r) decreased with increasing 4OHTam and endoxifen concentrations. The No-Observed Effect Concentrations (NOECs) calculated for the reproduction of the second generation exposed to 4OHTam and endoxifen were <1.8 and 4.3μg/L, respectively, whereas the NOECs that were calculated for the intrinsic rate of natural increase were <1.8 and 0.4μg/L, respectively. Our study raises questions about prodrug and active metabolites in environmental toxicology assessments of pharmaceuticals. Our findings also emphasize the importance of performing long-term experiments and considering multi-endpoints instead of the standard reproduction outcome.
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... Daphnids 110 were maintained at 15 individuals/L in 22 o C moderately hard water under a 16:8 light:dark 111 photoperiod in an environmental chamber. Each adult daphnid received approximately 6 X 10 6 112 cells of Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum) daily supplemented with a suspension of Tetrafin fish food (Tetra Holding Inc, VA) as described 114 previously (Baldwin et al., 1995; Karimullina et al., 2012 ...
The recently sequenced Daphnia pulex genome revealed the NR1L nuclear receptor group consisting of three novel receptors. Phylogenetic studies show that this group is related to the NR1I group (CAR/PXR/VDR) and the NR1J group (HR96), and were subsequently named HR97a/b/g. Each of the HR97 paralogs from Daphnia magna, a commonly used crustacean in toxicity testing, was cloned, sequenced, and partially characterized. Phylogenetic analysis indicates that the HR97 receptors are present in primitive arthropods such as the chelicerates but lost in insects. qPCR and immunohistochemistry demonstrate that each of the receptors is expressed near or at reproductive maturity, and that HR97g, the most ancient of the HR97 receptors, is primarily expressed in the gastrointestinal tract, mandibular region, and ovaries, consistent with a role in reproduction. Transactivation assays using an HR97a/b/g-GAL4 chimera indicate that unlike Daphnia HR96 that is promiscuous with respect to ligand recognition, the HR97 receptors do not respond to many of the ligands that activate CAR/PXR/HR96 nuclear receptors. Only three putative ligands of HR97 receptors were identified in this study: pyriproxyfen, methyl farnesoate, and arachidonic acid. Only arachidonic acid, which acts as an inverse agonist, alters HR97g activity at concentrations that would be considered within physiologically relevant ranges. Overall, this study demonstrates that, although closely related to the promiscuous receptors in the NR1I and NR1J groups, the HR97 receptors are mostly likely not multi-xenobiotic sensors, but rather may perform physiological functions, potentially in reproduction, unique to crustaceans and other non-insect arthropod groups.
... Thus, it is necessary to evaluate transgenerational effects by examining multigenerational exposure, which has rarely been investigated. A few studies were conducted regarding multigenerational effects of metals (Muyssen and Janssen, 2004) and pesticides (Liess et al., 2013), and individual adaptation of D. magna to estrogens (Baldwin et al., 1995), but until recently, studies concerning the effects of pharmaceuticals on nontarget organisms have been limited to acute and chronic studies with traditional endpoints. Although pharmaceuticals are present in the environment at levels that are too low to induce an acute toxic response, they may cause chronic sublethal effects. ...
... Incidence of hermaphroditism, delay in the settlement and metamorphosis, delay in the development to D-shape, developmental abnormalities, reduction in larval survival, and changes in the sex ratio towards females [52, 53] were found in the Pacific oyster Crassostrea gigas, which is of vital importance to the aquaculture industry. Elminius modestus and Balanus amphitrite, and the polychaete worm Dinophilus gyrociliatus have been studied545556575859606162636465. Several endocrine alterations have been found after exposure to NP at concentrations ranging from 0.1 to 100 µgL-1 (Table 2). ...
Nonylphenol is a metabolic intermediate from the microbial transformation of detergents used worldwide. While nonylphenol shows some acute toxicity, it is also able to mimic important hormones resulting in the disruption of several processes by interfering with the signals that control the overall physiology of the organism. This work perform a critical reviews on the origin, environmental fate, microbial transformation, ecosystems impact and endocrine disruption capacity of nonylphenol. Due to mass production of parent products and potential toxicity, nonylphenol is an example of a microbial decay product that may pose an environmental risk. The analysis supports the need for better tests to evaluate, model and monitor the potential long-term environmental impact of single compounds produced as a result of an environmentally- mediated degradation. Keywords. Nonylphenol, toxicity, Daphnia, transformation, ecosystem, environment, pollution
... decapods (Weis and Mantel, 1976; Fingerman and Fingerman, 1977; Reddy and Rao, 1987). In more recent publications Baldwin et al. (1995) and Zou and Fingerman (1997) could demonstrate that estrogens affect the moulting process in D. magna, possibly by interacting with the ecdysone receptor. Wollenberger (2005) summarised these findings, and demonstrated that larval development in A. tonsa is more sensitive than moulting in D. magna. ...
The marine calanoid copepod Acartia tonsa was exposed to methyltestosterone (MET, 1.6-126μgL(-1)), letrozole (LET, 10-1000μgL(-1)), triphenyltin chloride (TPT, 0.0014-0.0088μgL(-1) TPT-Sn) and fenarimol (FEN, 2.8-105μgL(-1)) for 21d covering a full life-cycle. All four compounds investigated are known to act as androgens in vertebrates. The digestive tract, musculature, nervous system, reproductive organs, gonad and accessory sexual glands were examined by light microscopy after routine staining and immune-labelling for detection of apoptosis and determination of proliferation activities. MET induced an inhibition of oogenesis, oocyte maturation and yolk formation, respectively, which was most pronounced at the lowest concentrations tested. In LET exposed males, spermatogenesis was enhanced with very prominent gamete stages; in some stages apoptosis occurred. The spermatophore was hypertrophied and displayed deformations. In females, LET induced a disorder of oogenesis and disturbances in yolk synthesis. TPT stimulated the male reproductive system at 0.0014 and 0.0035μg TPT-SnL(-1), whereas inhibiting effects were observed in the female gonad at 0.0088μg TPT-SnL(-1). In FEN exposed females proliferation of gametes was reduced and yolk formation showed irregular features at 2.8-105μgL(-1). In FEN exposed males an elevated proliferation activity was observed. No pathological alterations in other organ systems, e.g. the digestive tract including the hindgut acting as respiratory organ, the nervous system, or the musculature were seen. This indicates that the effects on gonads might be caused rather by disturbance of endocrine signalling or interference with hormone metabolism than by general toxicity.
... Incidence of hermaphroditism, delay in the settlement and metamorphosis, delay in the development to D-shape, developmental abnormalities, reduction in larval survival, and changes in the sex ratio towards females [52, 53] were found in the Pacific oyster Crassostrea gigas, which is of vital importance to the aquaculture industry. Elminius modestus and Balanus amphitrite, and the polychaete worm Dinophilus gyrociliatus have been studied545556575859606162636465. Several endocrine alterations have been found after exposure to NP at concentrations ranging from 0.1 to 100 µgL-1 (Table 2). ...
Nonylphenol is a metabolic intermediate from the microbial transformation of detergents used worldwide. While nonylphenol shows some acute toxicity, it is also able to mimic important hormones resulting in the disruption of several processes by interfering with the signals that control the overall physiology of the organism. This work perform a critical reviews on the origin, environmental fate, microbial transformation, ecosystems impact and endocrine disruption capacity of nonylphenol. Due to mass production of parent products and potential toxicity, nonylphenol is an example of a microbial decay product that may pose an environmental risk. The analysis supports the need for better tests to evaluate, model and monitor the potential long-term environmental impact of single compounds produced as a result of an environmentally-mediated degradation.
... Rather than a linear response to increasing BPA exposure, the highest increases in estrogen were recorded at the lowest BPA concentrations (10 g/L BPA) for both age classes. These results are consistent with other studies investigating the effects of xenoestrogens in both vertebrate (e.g., Welshons et al. 2006;Rubin 2011) and invertebrate (e.g., Baldwin et al. 1995;Vandenbergh et al. 2003) species. Vandenbergh et al. (2003) suggested that the U-shaped dose response they observed resulted from a receptor-mediated response as opposed to a direct effect on the hormone-producing glands or on the hormones themselves. ...
Bisphenol A (BPA) is an endocrine-disrupting compound that can enter aquatic systems through landfill leachate or wastewater effluent. Although impacts of BPA on vertebrates are well documented, its effects on invertebrates are less clear. Amphipods such as Gammarus pseudolimnaeus Bousfield, 1958 are often prevalent invertebrates in freshwater ecosystems and can provide a powerful invertebrate model system to investigate the endocrine-disruptive capabilities of BPA. However, techniques to assay hormone concentrations in amphipods, especially vertebrate-like steroid sex hormones, are not widespread. In this study, we (i) quantified estrogen concentrations in juveniles and in adult female amphipods; (ii) quantified testosterone concentrations in juveniles and in adult male amphipods; and (iii) delineated changes to estrogen
and testosterone concentrations of adults and juveniles following a 9-day exposure to BPA at four levels: 0 (control), 10, 50, and 100 �g/L BPA. Tissue extracts from homogenized samples were analyzed for estrogen or testosterone concentrations via radioimmunoassay for each reproductive class of amphipod. Low concentrations of BPA significantly increased estrogen concentrations in adult females and in juveniles. Moderate and high concentrations of BPA significantly increased testosterone concentrations in adult males, and low and moderate concentrations of BPA significantly increased testosterone concentrations of juveniles.
... This phenomenon was discovered in other studies (Wolfgang et al. 2003. Baldwin et al. 1995, Clubbs and Brooks 2007, Vandenbergh et al. 2003). The stimulation of reproduction and transgenerational effects of ß. calyciflorus in this study could be related to endocrine disruption. ...
The effects of fenitrothion on life history parameters, the production of resting eggs and hatching of resting eggs of the rotifer Brachionus calyciflorus were studied on the individual and population level. Neonates (<4 h-old) were individually cultured in six concentrations (0.1, 1, 10, 100, 1,000 and 2,000 pg L−1) of fenitrothion. Life history parameters including duration time of the juvenile period, hatching time of the first neonate, reproductive period, post-reproduction period, lifespan, and lifetime reproduction were evaluated. Fenitrothion significantly prolonged the juvenile period at 0.1 μg L−1 and extended hatching time of the first neonate at 1,000 μg L−1 Rotifers exposed to fenitrothion at concentrations of 0.1, 1, 10, and 100 pg L−1 had longer reproductive periods and produced more offspring than controls. Exposure to 1, 000 μg L−1 significantly reduced the number of resting eggs produced. Low concentrations of fenitrothion caused an increase in the duration of the juvenile period, reproductive period, and lifetime reproduction of B. calyciflorus.
... Ecdysteroids serve a functional role in crustaceans (and in platyhelminthes, nematodes, and annelids; Fingerman, 1997); 20-hydroxyecdysone, for example, controls the moulting processes in crustacea (and, perhaps, the production of vitellogenin), and although there is no direct evidence of impact of (xeno)oestrogens on synthesis of the ecdysteroid, links have been made with the inhibition of moulting and growth retardation (Charniaux-Cotton, 1985; Quackenbush, 1986; Zou & Fingerman, 1997a,b; Brown et al., 1999). Thus, several experimental studies indicate that oestrogens and oestrogen mimics such as alkylphenols could interact with crustacean developmental pathways: exposure to NP inhibits moulting, growth and the metabolic elimination of testosterone in the water £ea Daphnia magna (Comber et al., 1993; Baldwin et al., 1995; Zou & Fingerman, 1997b); prenatal NP exposure results in a high proportion of morphological deformities in juvenile Daphnia galeata (Shurin & Dodson, 1997); and life history e¡ects have been observed in the copepod Tisbe battagliai at NP concentrations of 20 mg l À1 (Bechmann, 1997 ). In barnacles Balanus amphitrite, low level exposure (0.01^10.0 mg l À1 ) to both NP and the natural hormone 17b-oestradiol (E2) can signi¢cantly reduce the settlement of cyprid larvae, and, in Elminius modestus, can disrupt the timing of larval development and reduce the size of resultant adults (Billinghurst et al., 1998Billinghurst et al., , 2001 ). ...
This review provides insights into the distribution and impact of oestrogens and xeno-oestrogens in the aquatic environment and highlights some significant knowledge gaps in our understanding of endocrine disrupting chemicals. Key areas of uncertainty in the assessment of risk include the role of estuarine sediments in mediating the fate and bioavailability of environmental (xeno)oestrogens (notably their transfer to benthic organisms and estuarine food chains), together with evidence for endocrine disruption in invertebrate populations.
Emphasis is placed on using published information to interpret the behaviour and effects of a small number of ‘model compounds’ thought to contribute to oestrogenic effects in nature; namely, the natural steroid 17β-oestradiol (E2) and the synthetic hormone 17α-ethinyloestradiol (EE2), together with the alkylphenols octyl- and nonyl-phenol (OP, NP) as oestrogen mimics. Individual sections of the review are devoted to sources and concentrations of (xeno)oestrogens in waterways, sediment partitioning and persistence, bioaccumulation rates and routes, assays and biomarkers of oestrogenicity, and, finally, a synopsis of reproductive and ecological effects in aquatic species.
... Ecdysteroids serve a functional role in crustaceans (and in platyhelminthes, nematodes, and annelids; Barker & Rees, 1990; Barker et al., 1990; Fingerman, 1997); 20-hydroxyecdysone, for example, controls the moulting processes in crustacea (and, perhaps, the production of vitellogenin), and although there is no direct evidence of impact of (xeno)oestrogens on synthesis of the ecdysteroid, links have been made with the inhibition of moulting and growth retardation (Charniaux-Cotton, 1985; Quackenbush, 1986; Zou & Fingerman, 1997a,b; Brown et al., 1999). Thus, several experimental studies indicate that oestrogens and oestrogen mimics such as alkylphenols could interact with crustacean developmental pathways: exposure to NP inhibits moulting, growth and the metabolic elimination of testosterone in the water £ea Daphnia magna (Comber et al., 1993; Baldwin et al., 1995; Zou & Fingerman, 1997b); prenatal NP exposure results in a high proportion of morphological deformities in juvenile Daphnia galeata (Shurin & Dodson, 1997); and life history e¡ects have been observed in the copepod Tisbe battagliai at NP concentrations of 20 mg l À1 (Bechmann, 1997). In barnacles Balanus amphitrite, low level exposure (0.01^10.0 mg l À1 ) to both NP and the natural hormone 17b-oestradiol (E2) can signi¢cantly reduce the settlement of cyprid larvae, and, in Elminius modestus, can disrupt the timing of larval development and reduce the size of resultant adults (Billinghurst et al., 1998, 2001). ...
This review provides insights into the distribution and impact of oestrogens and xeno-oestrogens in the aquatic environment and highlights some signi¢cant knowledge gaps in our understanding of endocrine disrupting chemicals. Key areas of uncertainty in the assessment of risk include the role of estuarine sedi- ments in mediating the fate and bioavailability of environmental (xeno)oestrogens (notably their transfer to benthic organisms and estuarine food chains), together with evidence for endocrine disruption in inver- tebrate populations. Emphasis is placed on using published information to interpret the behaviour and e¡ects of a small number of 'model compounds' thought to contribute to oestrogenic e¡ects in nature; namely, the natural steroid 17b-oestradiol (E2) and the synthetic hormone 17a-ethinyloestradiol (EE2), together with the alkyl- phenols octyl- and nonyl-phenol (OP, NP) as oestrogen mimics. Individual sections of the review are devoted to sources and concentrations of (xeno)oestrogens in waterways, sediment partitioning and persis- tence, bioaccumulation rates and routes, assays and biomarkers of oestrogenicity, and, ¢nally, a synopsis of reproductive and ecological e¡ects in aquatic species.
Description
Environmental Toxicology and Risk Assessment, 8th Volume (STP 1364) presents 29 peer-reviewed papers that provide you with the latest information on invertebrate and vertebrate endocrine disrupter screening assays and tests, in vitro endocrine disrupter testing, and an industrial perspective on endocrine screening testing. It focuses on the use of biomarker endpoints in toxicology and risk assessment, including biochemical, developmental, behavioral, and endocrine indicators.
Topics include: aquatic toxicology • behavioral toxicology • biochemical indicators • developmental indicators • endocrine indicators • biodegradation and fate of chemicals • quality assurance and quality control within laboratory and field studies • risk assessment and communication • and harmonization of standards development
This comprehensive text is an essential resource for environmental toxicologists, industry scientists dealing with product and chemical safety issues, and engineers and scientists dealing with chemcial treatment and disposal.
Description
Environmental Toxicology and Risk Assessment, 8th Volume (STP 1364) presents 29 peer-reviewed papers that provide you with the latest information on invertebrate and vertebrate endocrine disrupter screening assays and tests, in vitro endocrine disrupter testing, and an industrial perspective on endocrine screening testing. It focuses on the use of biomarker endpoints in toxicology and risk assessment, including biochemical, developmental, behavioral, and endocrine indicators.
Topics include: aquatic toxicology • behavioral toxicology • biochemical indicators • developmental indicators • endocrine indicators • biodegradation and fate of chemicals • quality assurance and quality control within laboratory and field studies • risk assessment and communication • and harmonization of standards development
This comprehensive text is an essential resource for environmental toxicologists, industry scientists dealing with product and chemical safety issues, and engineers and scientists dealing with chemcial treatment and disposal.
With the widespread use of diethylstilbestrol (DES), it has become a common contaminant in the aquatic environment. It is toxic to a wide range of aquatic organisms, disrupting the water flea growth and further interfering with several ecosystem services. Nevertheless, the molecular mechanism of DES in water fleas is still unexplicit. In this study, the 21-day chronic test showed that a negative effect of growth and reproduction can be observed with DES exposure. Subsequently applied transcriptomic analysis illustrated the molecular mechanism in mode freshwater invertebrate Daphnia magna (D. magna) exposed to 2, 200, and 1000 μg·L−1 of DES for 9 days. Meanwhile, exposure to DES at 200 and 1000 μg·L−1 significantly restrains the growth (body length) and reproduction (first spawning time) of D. magna. Identified differentially expressed genes (DEGs) are majorly enriched relative to energy metabolism, lipid metabolism, the digestive system, transport and catabolism pathways which were remarkably changed. These repressed and up-regulated pathways, in relation to energy synthesis and metabolism, may be the reasons for the reduced body length and delayed first spawning time. Taken together, this study revealed that DES is a threat to D. magna in the aquatic environment and clarifies the molecular mechanism of the toxicity.
Parabens are widely used as preservatives in pharmaceuticals, cosmetics, and food products. Ethylparaben (EP) and propylparaben (PP) are particularly preferred because of their bactericidal and fungicidal effects. Although generally described as safe compounds, many studies have reported that parabens have estrogenic and endocrine-disrupting properties. In the present study, the effects of EP and PP (50 mM, 100 mM and 200 mM) on Drosophila melanogaster development and fecundity were investigated. No differences were found in the pupation and maturation percentages in all concentrations of parabens (p>0.05). However, it was found that the mean pupation and maturation times increased in all treatment groups (p<0.05). A statistically significant decrease (p<0.05) in the number of offspring of the 200 mM ethylparaben exposure group was observed. In all paraben groups, a significant reduction in mean fecundity was found compared to the control group (p<0.05).
With the ever-increasing consumption of pharmaceutical compounds, their presence in the environment is now an undisputable reality. The majority of these compounds are released into the wild after their therapeutic use, as biotransformation products or in their original form. The presence of this class of compounds in the environment, due to their biological properties, can exert effects on non-target organisms, with adverse consequences. In addition, some bioactive substances, such as stimulants of the central nervous system, are also used by humans as part of their diet. The adverse consequences posed by such chemicals may be permanent or transient, if the exposure to xenobiotics is halted; it is thus of the paramount importance to study effects that result from long-term exposure to toxicants, but also the recovery of organisms previously exposed to such substances, especially if such chemicals may cause some type of addiction. Caffeine (1,3,7-trimethylxanthine) is a naturally occurring alkaloid found in many plants, being one of the most common stimulant/pharmaceutical compounds found in the environment. In addition, it is addictive, and strongly consumed by humans, a factor that contributes also for its continuous presence in the aquatic environment. The aim of this study was to evaluate the effects of environmentally relevant concentrations (0.08; 0.4; 2; 10; and 50 μg/L) of caffeine on behavior and physiological parameters (that are proxies of metabolic traits, such as oxygen uptake and glycogen content), in individuals of the freshwater crustacean species Daphnia magna, of distinct ages, and with or without a recovery period in the absence of caffeine. Regarding behavior, the results indicated that caffeine exposure altered the moved distance of the test organisms, but not according to a coherent pattern; low concentrations of caffeine reduced the movement of exposed daphnids, while higher levels did not have any measurable effect on this parameter. In addition, it was possible to identify subtle withdrawal effects (animals exposed to caffeine during 21 days and kept in uncontaminated media for 2 days). Regarding the other two studied parameters, caffeine exposure did not result in any significant modification in oxygen uptake and glycogen stores/reserves of the test organisms, in animals continuously exposed, or in those subjected to a recovery period, suggesting that despite a behavioral stimulatory effect, this was not followed by any metabolic change, and no addictive effect was possible to infer. The results showed that the presence of caffeine in environmental concentrations can induce mild behavioral effects at low, albeit realistic levels, but not capable of establishing clear biochemical changes.
As a synthetic estrogen, 17α-ethynylestradiol (EE2) has been known to show the strong estrogenic potency. This work critically reviewed the occurrence and removal of EE2 in municipal wastewater treatment plants (WWTPs). Based on the on-site investigations from 282 municipal WWTPs across 29 countries, the concentrations of EE2 in influent and effluent ranged from n.d-7890 and n.d-549 ng/L, with respective average concentrations of 78.4 and 12.3 ng/L. The average effluent concentration of EE2 was more than 61 times higher than the reported lowest-observed-effect concentration, indicating an urgent need for removing EE2 in WWTPs. The calculated removal efficiencies of EE2 in different wastewater treatment processes varied from -100%-100%. Averagely, 47.5% of EE2 was removed in the primary treatment process, 55.3% by biological filter treatment, 59.4% by lagoon and 71.5% by activated sludge process. The observed removal of EE2 in municipal WWTP could be mainly attributed to adsorption and biodegradation, which could be predicted according to its solid-water distribution coefficients and biodegradation rate constants. However, it should be noted that the predicted removal of EE2 was found to deviate from the in-plant observation, likely attributing to the existence of EE2 conjugates in raw municipal wastewater. Therefore, the effect of EE2 conjugates on the EE2 removal in WWTPs should be taken into account in future.
Chemical pesticides are widely used around the world, but at the same time, they may cause direct or indirect risks to many non-target organisms. Recent increased use of insecticides in coastal areas, for example to control invasive tawny crazy ants, raises concern that insecticides may affect ecologically and/or commercially important species found in estuaries. Here, we investigated the lethal and sub-lethal effects of fipronil on juvenile brown shrimp Farfantepenaeus aztecus over 29 days at five different nominal concentrations (0.1, 1.0, 3.0, 6.4, and 10.0 µg/L) in a laboratory experiment. Exposure to all of the fipronil treatments resulted in all individuals dying before the end of the experiment; whereas, no individual died in the control (0.0 µg/L). The 96-hour LC50 was determined to be 1.3 µg/L. Shrimp also experienced weight loss under all of the fipronil treatments. Inter-moult interval was increased from 12.2 ± 1.64 day in the control group to 15.5 ± 0.53 day in the 1.0 μg/L treatment. Lipid content of shrimp increased significantly in a concentration-dependent manner. Finally, behavioral and body color changes were also observed under the fipronil treatments. We conclude F. aztecus is very sensitive to fipronil and monitoring is needed in coastal areas.
Because xenosensing nuclear receptors are also lipid sensors that regulate lipid allocation, we hypothesized that toxicant-induced modulation of HR96 activity would alter lipid profiles and the balance between adult survival and neonate production following exposure in Daphnia magna. Adult daphnids were exposed to unsaturated fatty acid- and toxicant- activators or inhibitors of HR96 and later starved to test whether chemical exposure altered allocation toward survival or reproduction. The HR96 activators, linoleic acid and atrazine, decreased reproduction as expected with concomitant changes in the expression of HR96 regulated genes such as magro. The HR96 inhibitors, docosahexaenoic acid (DHA) and triclosan, increased reproduction or neonate starvation survival, respectively. However, pre-exposure to triclosan increased in neonate survival at the expense of reproductive maturation. Lipidomic analysis revealed that sphingomyelins (SM) are predominantly found in neonates and therefore we propose are important in development. DHA and triclosan increased neonatal SM, consistent with HR96’s regulation of Niemann-Pick genes. While DHA altered expression of magro, Niemann-Pick 1b, mannosidase, and other HR96-regulated genes as expected, triclosan primarily perturbed sphingomyelinase and mannosidase expression indicating different but potentially overlapping mechanisms for perturbing SM. Overall, SM appears to be a key lipid in Daphnia maturation and further support was provided by carmofur, which inhibits sphingomyelin/ceramide metabolism and in turn severely represses Daphnia maturation and initial brood production. In conclusion, toxicants can perturb lipid allocation and in turn impair development and reproduction.
Endocrine disruptors are chemicals which can be found in our normal daily lives. Chemicals such as bisphenol A, DDT, benzophenone and phenylphenol can be easily ingested through plastic food containers and pesticides. Endocrine disruptors can be very harmful and toxic because they disrupt the normal function of the endocrine system. It has been reported that endocrine disruptions can cause fatal strikes in the cardiovascular, reproductive, and central nervous systems, and other parts of the body. Therefore we examined if benzophenone as an endocrine disruptor inhibits development in or induces malformation of chick embryos. Chick embryos which received a single injection of benzophenone (1?g/egg \sim500?g/egg) via the yolk sac at designated times (6, 9, 12, 15, 18 and 21 days after incubation) were investigated. Body weight reduction was observed in middle doses (40?g/egg \sim60?g/egg). High mortality rates and teratogenic signs such as abnormal wry beak and abnormal eyeballs were seen in high doses (80?g/egg \sim500?g/egg). In conclusion, it is suggested that benzophenone induces malformation of chick embryos and seriously inhibits development.
The Upper Vistula Basin, in Southern Poland, is a diverse area, with a number of environmental problems. The working group discussed three primary ecosystem types within this area: forest catchments, urban areas, and retention reservoirs. Environmental conditions and current monitoring efforts were well presented for the forest catchments and urban areas; much less information was presented for retention reservoirs. Accordingly, the working group was able to make specific recommendations for incorporation of biomarkers in any programmes to ascertain the efficacy of remediation efforts in the first two ecosystem types listed above. Those recommendations are given at the end of this chapter. The working group recommended further assessment of the environmental quality of the region’s retention reservoirs, as an obligatory first step in determination of the suitability of similar biomarker approaches. Overall, the working group was favourably impressed with the ongoing and planned environmental assessment efforts of scientists in this region.
One of the primary channels of sensory input for zooplankton are chemical signals. Much zooplankton behavior is triggered by chemical stimuli, including feeding, predator defense, mating, and migration. Chemically regulated zooplankton behavior affects larger scale ecosystem processes like grazing, recruitment and secondary production. Knowledge of how chemicals transmit information about location, food quality, conspecifics, competitors, and predators is critical for understanding how aquatic ecosystems function. This paper reviews the behavioral evidence that planktonic rotifers respond to a variety of chemical stimuli. Although a rich variety of rotifer behaviors are regulated by chemical signals, little progress has been made to isolate and characterize these stimuli. If aquatic ecology is to become a predictive science, knowledge of the mechanisms causing the observed interactions is necessary. Chemical signals need to be isolated, purified, and characterized, and their causal role in regulating population and community processes needs to be demonstrated. Rotifers have chemosensory neurons in their corona and electron microscopy has revealed chemoreceptive pores in the anterior integument of several species. Some rotifers use these chemoreceptors to discriminate food particles based on the flavors on the cell surface. In Asplanchna, prey are discriminated by contact chemoreception. Asplanchna releases a waterborne signal that induces spine formation in several Brachionus species, Keratella cochlearis, K. slacki, and Filinia longisecta. The colonial Sinatherina socialis is defended against fish predation by warts containing unpalatable chemicals that have yet to be identified. Larval settlement in Collotheca gracillipes is determined by the chemistry of aquatic plant surfaces. Larvae prefer the undersurface of leaves where there is a low Ca++ microhabitat due to photosynthesis. Oviposition in Euchlanis dilatata is restricted to plant surfaces familiar to the maternal female. Hydrogen peroxide and certain prostaglandins stimulate resting egg hatching even in the dark. Sexual reproduction and polymorphism in Asplanchna sieboldi is regulated by dietary tocopherol. A chemical signal that allows assessment of conspecific population density is detected in conditioned media by several rotifer species. Water soluble extracts of Brachionus plicatilis increase mictic female production 1.7 times more than controls. Unknown compounds produced by certain bacteria also increase mixis 4–10 fold over controls. Mate recognition in B. plicatilis is determined by a 29 kD surface glycoprotein called the mate recognition pheromone (MRP). The MRP has been isolated, purified, and a polyclonal antibody against it has been prepared. The structure of the oligosaccharide and protein components of the MRP are currently being characterized. Elucidation of the chemicals regulating rotifer life cycles will make important contributions to the understanding of ecological processes in aquatic communities.
The hypothesis has been put forward that humans and wildlife species adverse suffered adverse health effects after exposure to endocrine-disrupting chemicals. Reported adverse effects include declines in populations, increases in cancers, and reduced reproductive function. The U.S. Environmental Protection Agency sponsored a workshop in April 1995 to bring together interested parties in an effort to identify research gaps related to this hypothesis and to establish priorities for future research activities. Approximately 90 invited participants were organized into work groups developed around the principal reported health effects-carcinogenesis, reproductive toxicity, neurotoxicity, and immunotoxicity-as well as along the risk assessment paradigm-hazard identification, dose-response assessment, exposure assessment, and risk characterization. Attention focused on both ecological and human health effects. In general, group felt that the hypothesis warranted a concerted research effort to evaluate its validity and that research should focus primarily on effects on development of reproductive capability, on improved exposure assessment, and on the effects of mixtures. This report summarizes the discussions of the work groups and details the recommendations for additional research.
The EU Medicinal Products Directive (65/65/EEC) has been amended to require an environmental risk assessment (ERA) for human pharmaceuticals effective January 1995. At present, official ERA guidelines have yet to be finalised. Previous discussions about their nature have taken place in the absence of a systematic analysis of the potential environmental impacts of pharmaceuticals. This study attempts to address this deficiency via a review of existing ecotoxicity data. Acute ecotoxicity data relating to >100 human pharmaceuticals have been collated. They suggest a lack of acute effects at <100 µg/l in standard tests. Relative sensitivity based on acute effects was algae (most sensitive) > Daphnia > fish. Chronic effects data were limited and this was identified as a shortcoming. This was reinforced by observations of large differences between acute and chronic responses to steroids in fish. The availability of UK usage data permitted risk characterisation i.e., calculation of PEC/PNEC ratios for >60 compounds. Under "worst-case" fate assumptions of no human metabolism, passage of all material to drain, no removal during wastewater treatment and no surface water dilution of effluent, the large majority of pharmaceuticals yielded PEC/PNEC ratios <1 (in theory implying environmental safety). For the remainder, a consideration of surface water dilution and expected wastewater treatment removal was sufficient to yield PEC/PNEC <1. PNEC was based on acute effects data with an assessment factor of 1,000. These assessments ignore the potential for multiple exposure/mixture effects. Calculation of potential lifetime ingestion via drinking water employing “worst-case” assumptions (as above and no removal during drinking water treatment) revealed I70 values (based on ingestion of 2 litres/day for 70 years) generally equivalent to 2 days of the corresponding daily therapeutic doses. Refinement of the exposure calculations or comparisons with monitoring data confirmed the degree of conservatism associated with the “worst-case” exposure estimations.
Invertebrates offer a number of advantages for in situ measurement using animal biomarkers. Their ability to colonize many different compartments of terrestrial and aquatic ecosystems mainly result from both the development of various strategies for resource exploitation and a high biotic potential as expressed by fast growth and high reproduction rates for most species. Due to their position at different levels in food webs, invertebrates play functional key-roles in ecosystems and when affected by chemicals, they can be responsible for dramatic changes in community structure and function. Therefore, they display a great potential for evaluating the ecological impact of pollutants. Adaptability is probably a key-feature of invertebrates in heavily deteriorated environments. Invertebrates can thus be found in highly polluted habitats where vertebrates are virtually absent. In this case, they frequently represent the only way to evaluate the effects of pollutants on animal biological systems. Biomarkers measured in invertebrates allow diagnosis of long-term effects of chemicals. The development of resistance to toxic chemicals, physiological adaptation involving changes in metabolic energy allocation, occurrence of morphological or anatomical abnormalities, are situations in which changes induced by long-term exposure of the individuals have consequences on population structure and dynamics. Biomarkers measured at the individual level may thus be linked with population changes from which further impact on community structure and function may be expected. Such an approach can be used to classify polluted areas according to the level of ecological damage in order to identify priority cases for remediation. The same biomarkers can then be used as early signs of biological restoration of damaged ecosystems. For example, enzymatic biomarkers can indicate decreased levels of resistance within exposed populations as a result of decreased selection pressure on individuals. Similarly, changes in energy allocation, as assessed through individual evaluation of scope for growth and scope for reproduction, can occur as a response to better environment conditions and may result in changes in population dynamics. Measurement of biomarkers in invertebrates certainly provide valuable information on both the ecological impact of long-term chemical contamination (diagnostic approach) and the conditions of biological restoration of damaged ecosystems (predictive approach). Both approaches however require a pertinent choice of invertebrate species and the assessment of linkable responses at different levels of biological organisation.
There is a growing literature relating to observations of human pharmaceuticals in the environment. Discussions about the environmental consequences of the presence of such compounds have taken place in the general absence of a systematic analysis of the potential risk. This can partly be attributed to the lack of public domain information relating to the ecotoxicity of pharmaceuticals. The lack of such an analysis means that to date, decisions concerning environmental risk assessment criteria and/or regulatory thresholds have been somewhat arbitrary or based upon inappropriate groups of industrial chemicals such as pesticides. This study attempts to address that deficiency and collates examples of data relating to the ecotoxicity of existing human pharmaceuticals. The intention is to provide perspective that will prove useful during the further development of assessment criteria. The database may also prove useful in the context of the risk assessment of individual substances.
http://rd.springer.com/chapter/10.1007/978-3-662-04634-0_15
There has been global concern about the effect of toxic chemicals on
aquatic biota due to the upsurge in contamination of aquatic ecosystems
by these chemicals, which includes pesticides. Roundup® and other
glyphosate-based herbicides are frequently used in the chemical control
of weeds and invading alien plant species in South Africa. These
bio-active chemicals ultimately get into water courses directly or
indirectly through processes such as drifting, leaching, surface runoff
and foliar spray of aquatic nuisance plants. However, there is no South
African water quality guideline to protect indigenous freshwater
non-target organisms from the toxic effects of glyphosate-based
herbicides. This study evaluated the possible use of growth measures in
Caridina nilotica as biomarkers of Roundup® pollution as part of
developing glyphosate water quality guideline for the protection of
aquatic life in South Africa. Using static-renewal methods in a 25-day
growth toxicity test, 40 days post hatch shrimps were exposed to
different sub-lethal Roundup® concentrations of 0.0 (control), 2.2,
2.8, 3.4, 4.3 and 5.4 mg/L. Shrimps were fed daily with TetraMin®
flake food and test solutions changed every third day. Shrimp total
lengths and wet weights were measured every fifth day. These data were
used to determine the shrimp's growth performance and feed utilization
in terms of percent weight gain (PWG), percent length gain (PLG),
specific growth rate (SGR), condition factor (CF), feed intake (FI),
feed conversion ratio (FCR) and feed conversion efficiency (FCE).
Moulting was observed for 14 days and the data used to determine the
daily moult rate for each concentration. Results of growth performance
and food utilization indices showed that growth was significantly
impaired in all exposed groups compared to control (p < 0.05).
Moulting frequency was also higher in all exposed groups than in control
(p < 0.05). Although all the tested growth measures proved to be
possible biomarkers of Roundup® pollution, moulting frequency gives
a clearer indication of the sub-lethal effects of Roundup® toxicity.
In einer umfassenden Literaturrecherche wurde eine aktuelle Bestandsaufnahme der in Deutschland und im europäischen Ausland vorliegenden Monitoringdaten zum Vorkommen und Verhalten von Arzneimitteln in der Umwelt erarbeitet. Die in vielfältigen Monitoringkampagnen gemessenen Umweltkonzentrationen sowie Ergebnisse ökotoxikologischer und physiko-chemischer Untersuchungen wurden in Datenbanken eingepflegt, die eine Auswertung im Hinblick auf die Identifizierung prioritärer Arzneistoffe und die Entwicklung von Monitoringstrategien erlauben.
Die erstellte Datenbank MEC weist 274 Arzneistoffe (Human- und Veterinärpharmaka, davon 27 Wirkstoff-Metaboliten) aus, für die Konzentrationen in einer der Umweltmatrices Kläranlagenablauf, Oberflächengewässer, Grundwasser, Trinkwasser, Klärschlamm, Wirtschaftsdünger, Boden oder Sediment gemessen wurden (10.150 Datenbankeinträge). Die Datenbank ÖKOTOX umfasst 251 Wirkstoffe, für die ökotoxikologische Wirkparameter für wenigstens einen Testorganismus vorliegen, und die Datenbank Umweltverhalten enthält physiko-chemische Parameter für 183 Wirkstoffe. Die Zitate der für die Zusammenstellung dieser Datenbanken gesichteten Literatur (1.382 Zitate) werden für eine weitere Nutzung im Literaturverwaltungsprogramm Referenzmanager bereitgestellt.
Die Auswertung der Datenbanken zeigt, dass nur für eine Schnittmenge von 70 Wirkstoffen eine Bewertung der Umweltkonzentrationen anhand ökotoxikologischer Wirkkonzentrationen möglich ist. Durch die Abschätzung von PNEC-Werten (Predicted No Effect Concentration) konnten 19 Wirkstoffe mit gesicherter und 9 Wirkstoffe mit mangelhafter Datenlage identifiziert werden, für die aufgrund der gemessenen Umweltkonzentrationen eine Gefährdung des Ökosystems in mindestens einem Gewässerabschnitt in Deutschland befürchtet werden muss. Eine besondere Aufmerksamkeit sollte den „neuen“ Arzneistoffen geschenkt werden, für die derzeit noch keine Umweltkonzentrationen und/oder ökotoxikologischen Daten für eine zuverlässige Gefährdungsabschätzung vorliegen, deren zum Teil drastische Zunahme der Verbrauchsmengen aber ein hohes Gefährdungspotenzial erwarten lässt.
Eine von den Autoren vorgenommene Priorisierung der Arzneistoffe berücksichtigt das ökotoxikologische
Wirkpotenzial, das Vorkommen in der aquatischen Umwelt (Oberflächen-, Grund- und Trinkwasser) sowie die Entwicklung der Verbrauchsmengen im Zeitraum 2002 bis 2009. Das Resultat ist eine Zusammenstellung prioritärer Wirkstoffe (Tabelle 19):
* 24 Stoffe mit hoher Priorität
* 17 Stoffe mit mittlerer Priorität
* 56 Stoffe, die beobachtet werden sollten, weil die Verbrauchsmengen stark zunehmen
und/oder verlässliche Daten zu Umwelt- und Wirkkonzentrationen fehlen
Aufbauend auf der Priorisierung werden Strategien für ein effizientes Umweltmonitoring vorgeschlagen,
welche der zahlreichen Arzneistoffe (und ihrer Metabolite) an welchen Probenahmestellen in welcher Häufigkeit mit dem Ziel zu untersuchen sind, um
* belastete Oberflächengewässer zu identifizieren, in denen eine Gefährdung des Ökosystems
durch Arzneistoffe nicht ausgeschlossen werden kann und
* Grundwasserkörper zu identifizieren, die durch Infiltration belasteter Oberflächengewässer
und/oder belasteten Sickerwassers mit Arzneistoffen kontaminiert werden, so
dass eine hygienisch-ästhetische Beeinträchtigung des daraus gewonnenen Trinkwassers
nicht ausgeschlossen werden kann.
Most oil and gas installations produce significant quantities of associated water which has to be disposed of. Offshore, produced water (PW) is often discharged in the sea, after treatment. Impact of such discharge on the marine environment is a concern in the North Sea, due in particular to the presence of polycyclic aromatic hydrocarbons (PAH) in the PW discharged. In order to assess the impact of PAHs on fish and fish eggs, a laboratory study encompassing various techniques – some of which are fairly new – has been recently performed, the results of which are presented in this paper. Fish were exposed to various concentrations of North Sea oil dispersed in water. Disturbed egg production of exposed fish and reduced hatching success due to maternal transfer were observed in fish exposed to oil concentrations in the range 0.4-0.7 mg/L. In particular no effect on egg production of fish was detected below 0.4 mg/L oil and no effect on hatching success due to maternal transfer was detected below 0.7 mg/L, although significant biomarker responses (PAHs metabolites and DNA adducts) were observed at 0.1 mg/L oil. Due to the relatively high concentrations tested in these experiments, it is unfortunately not yet possible to extrapolate the results to actual field concentrations (< 0.1 mg/L) and further studies at lower concentrations are needed.
The continuous discharge of pharmaceuticals into the environment results in the chronic exposure of aquatic organisms to complex drug mixtures. We examined the influence of a mixture of pharmaceuticals (carbamazepine (CBZ), diclofenac (DIC), metoprolol (MET) and 17-ethinylestradiol (EE2)) at environmentally relevant ('env') and artificially high ('high') concentrations on Gammarus fossarum. Different sublethal responses such as moulting, reproduction and the content of the energy-storage component glycogen were analysed. The drug mixture influenced the moulting behaviour of gammarids at both the 'env' and 'high' concentration levels, leading to a discontinuous increase of body length in successive moults, compared with the constant increase of body length in the control treatment. Moreover, the time between successive moults of animals exposed to the 'env' and 'high' pharmaceutical concentrations was decreased because of shortened intermoult periods. We observed no significant impact of the pharmaceuticals on reproduction. In addition, the content of glycogen was not significantly affected by the drug mixture. Permanent exposure of G. fossarum to a wider range of pharmaceuticals in natural aquatic systems may influence moulting behaviour and accompanied life-history parameters, followed by severe ecological consequences as gammarids play an important role in many freshwater ecosystems of the northern hemisphere.
The BII bioassay was developed as a rapid and reliable tool for detecting potential insect growth regulators acting as ecdysteroid receptor (ant)agonists. Based on an ecdysteroid-responsive cell line from Drosophila melanogaster, this microplate assay is ideally suited to the evaluation of environmental contaminants as potential endocrine disrupters. Data are presented for about 80 potential environmental contaminants, including industrial chemicals, pesticides, Pharmaceuticals, phytoestrogens, and vertebrate steroids, and are compared with data for known (ant)agonists. Apart from androst-4-ene-3,17-dione (a weak antagonist), vertebrate steroids were inactive at concentrations up to 10−3 M. The vast majority of xenobiotics also showed no (ant)agonist activity. Among the industrial chemicals, antagonistic activity was observed for bisphenol A median effective concentration (EC50) of 1.0 × 10−4 M and diethylphthalate (EC50 of 2.0 × 10−3 M). Some organochlorine compounds also showed weak antagonistic activity, including o,p′-dichlorodiphenyldichloroethylene (DDE), p,p′-DDE, dieldrin, and lindane (EC50 of 3.0 × 10−5 M). For lindane, bisphenol A, and diethylphthalate, activity is not associated with impurities in the samples and, for lindane and bisphenol A at least, the compounds are able to compete with ecdysteroids for the ligand binding site on the receptor complex, albeit at concentrations very much higher than those found in the environment. The only pharmaceutical showing any detectable antagonist activity was 17α-ethynylestradiol. In the context of recent publications on potential endocrine disruption in marine and freshwater arthropods, these findings suggest that, for some compounds (e.g., diethylstilbestrol), ecdysteroid receptor-mediated responses are unlikely to be involved in producing chronic effects. The BII assay has a potentially valuable role to play in distinguishing between endocrine-mediated, which normally occur at submicromolar concentrations, and pharmacological effects in insects and crustaceans.
Exposure to substances possessing sex steroid activities can adversely effect endocrine and reproductive systems in humans and wildlife. Studies have found significant increases in the incidence of breast, prostate and testicular cancer. The others have reported decreasing sperm counts and semen volume and longer times to conception. These findings are complemented by field study data indicating that wild and domesticated organisms are also experiencing compromised reproductive and developmental abruptions.The paper presents the review of recent works conducted in the field of specific environmental pollution posed by endocrine disrupting compounds (EDCs). The modes of toxic action, division of chemicals belonging to EDCs, in vivo and in vitro assays serving endocrine potency determination, as well as results of concentration levels determinations in air, water and solid samples are given in a comprehensive way.
Intense efforts are currently being made to develop procedures to assess the potential for endocrine disruption in aquatic environments. Most attention has focused on fresh water systems, amphibians and fish and morphological and molecular measures for endocrine disruption. A biomarker approach involving the induction of a female-specific protein, vitellogenin, in males by exposure to xeno-oestrogens has proved particularly useful. By contrast marine environments and invertebrates have received comparatively little attention. The present study aimed to examine the effects of exposure to a xeno-oetrogen, 4-n-nonylphenol (4-NP) and a natural oestrogen, 17β-oestradiol (E2) on a marine crustacean, the barnacle Balanus amphitrite. In particular, the effect of such exposure on levels of a larval storage protein, cypris major protein (CMP), which is related to barnacle vitellin, has been examined. Accordingly, nauplius stage larvae of B. amphitrite were exposed to low concentrations (0.01–1.0 μg l−1) of 4-NP and E2 (1.0 μg l−1) from egg hatching until the cypris stage. SDS–PAGE and immunoblotting were used to monitor CMP levels in exposed larvae relative to ‘zero’ concentration controls. Elevated (100% increase) CMP levels were measured in larvae exposed to both 4-NP and E2 at a concentration of 1.0 μg l−1, and notable increases occurred at lower concentrations of 4-NP. It is concluded that CMP and perhaps other vitellin-like proteins are potential biomarkers of low level oestrogen exposure in crustaceans.
The relative sensitivity of amphibians to chemicals in the environment, including plant protection product active substances, is the subject of ongoing scientific debate. The objective of this study was to compare systematically the relative sensitivity of amphibians and fish to chemicals. Acute and chronic toxicity data were obtained from the U.S. Environmental Protection Agency (U.S. EPA) ECOTOX database and were supplemented with data from the scientific and regulatory literature. The overall outcome is that fish and amphibian toxicity data are highly correlated and that fish are more sensitive (both acute and chronic) than amphibians. In terms of acute sensitivity, amphibians were between 10- and 100-fold more sensitive than fish for only four of 55 chemicals and more than 100-fold more sensitive for only two chemicals. However, a detailed inspection of these cases showed a similar acute sensitivity of fish and amphibians. Chronic toxicity data for fish were available for 52 chemicals. Amphibians were between 10- and 100-fold more sensitive than fish for only two substances (carbaryl and dexamethasone) and greater than 100-fold more sensitive for only a single chemical (sodium perchlorate). The comparison for carbaryl was subsequently determined to be unreliable and that for sodium perchlorate is a potential artifact of the exposure medium. Only a substance such as dexamethasone, which interferes with a specific aspect of amphibian metamorphosis, might not be detected using fish tests. However, several other compounds known to influence amphibian metamorphosis were included in the analysis, and these did not affect amphibians disproportionately. These analyses suggest that additional amphibian testing is not necessary during chemical risk assessment. Environ. Toxicol. Chem. © 2013 SETAC.
The effects of an oestrogenic compound, similar to those recently linked with falling human sperm counts, were investigated in two common freshwater organisms commonly used in education
Oestrogenic compounds have recently been linked with falling sperm counts in human males and also with cancer of the testes and breast. If these compounds can have such dangerous and dramatic effects in humans, as well as affecting sexual behaviour and physiology of fish, what effects do they have on other members of freshwater food chains? The aim of this investigation was to perform some simple experiments using basic laboratory facilities for student research projects. Daphnia, an important primary consumer and food source for fish, was exposed to increasing amounts of ethynyloestradiol, an oestrogen commonly used in contraceptive tablets. The higher concentrations of the oestrogen (0.1 to 1.0 ppm) were found to significantly reduce the heart rate of the Daphnia after approximately 30 minutes' exposure. It is proposed that such a reduction in the activity of oestrogen exposed Daphnia would make them more prone to predation and therefore increase the accumulation of oestrogens by fish. A further experiment investigated the effects of the oestrogen on photosynthesis in Elodea, a common pond weed. The same concentrations of ethynyloestradiol increased photosynthetic rates which could lead to a proliferation in growth. This again would promote the transfer of these compounds if they accumulate in the tissues for aquatic plants. These experiments on a currently significant topic were performed using readily available organisms and a small capital expenditure, thus making them a pertinent and interesting practical for both Alevel and undergraduate students.
1.1. The metabolism of two tritium labelled vertebrate-type steroids was studied in two insect species, i.e. the fleshfly, Sarcophaga bullata, and the Colorado potato beetle, Leptinotarsa decemlineata.2.2. After injection of [3H]androstenedione into Sarcophaga bullata pharate adults, testosterone (both as free steroid and as conjugate) could be identified as a metabolic product. This indicates the presence of the 17β-hydroxysteroid dehydrogenase (HSD) enzyme in the fleshfly.3.3. Injection of 17α-hydroxy[3H]progesterone into Leptinotarsa decemlineata last instar larvae resulted in the formation of 17α-hydroxy-20α-dihydroprogesterone, 17α-hydroxy-20β-dihydroprogesterone and their conjugates. This indicates the presence of both the 20α-HSD and the 20β-HSD enzyme in Leptinotarsa.4.4. Important conversions in the biosynthetic pathway of steroids in vertebrates, such as the conversion of 17α-hydroxyprogesterone to androgens (Leptinotarsa) and the aromatization of androgens to estrogens (Sarcophaga), were not demonstrated in the metabolic studies.
Large numbers and large quantities of endocrine-disrupting chemicals have been released into the environment since World War II. Many of these chemicals can disturb development of the endocrine system and of the organs that respond to endocrine signals in organisms indirectly exposed during prenatal and/or early postnatal life; effects of exposure during development are permanent and irreversible. The risk to the developing organism can also stem from direct exposure of the offspring after birth or hatching. In addition, transgenerational exposure can result from the exposure of the mother to a chemical at any time throughout her life before producing offspring due to persistence of endocrine-disrupting chemicals in body fat, which is mobilized during egg laying or pregnancy and lactation. Mechanisms underlying the disruption of the development of vital systems, such as the endocrine, reproductive, and immune systems, are discussed with reference to wildlife, laboratory animals, and humans.
Estrogenic pesticides such as DDT and chlordecone generate deleterious reproductive effects. An "in culture" bioassay was used to assess the estrogenicity of several pesticides. The E-screen test uses human breast estrogen-sensitive MCF7 cells and compares the cell yield achieved after 6 days of culture in medium supplemented with 5% charcoal-dextran stripped human serum in the presence (positive control) or absence (negative control) of estradiol and with diverse concentrations of xenobiotics suspected of being estrogenic. Among the organochlorine pesticides tested, toxaphene, dieldrin, and endosulfan had estrogenic properties comparable to those of DDT and chlordecone; the latter are known to be estrogenic in rodent models. The E-screen test also revealed that estrogenic chemicals may act cumulatively; when mixed together they induce estrogenic responses at concentrations lower than those required when each compound is administered alone.
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Polygynous mating in Herring Gulls has been found only in northern Great Lakes breeding colonies. In 1978, I censused 21 colonies in northern Lake Michigan and Lake Huron to provide a baseline from which to gauge any future changes in the distribution and frequency of polygyny. Among 10,740 nests, I found 33 (0.3%) double-nests. Double-nests are two contiguous nest cups that contain eggs and are attended by one male and two females. I also found 30 (0.3%) nests with more than four eggs. These nests usually are attended by only two females (female associations). Polygynous groups and female associations were concentrated in northeastern Lake Michigan. The simultaneous occurrence of polygyny and female associations in Great Lakes Herring Gulls differs from the situation in other gull species in which only female associations have been described.
[On montre que pour Daphnia magna le changement de la parthénogenèse à la reproduction sexuelle est causé par l'action réciproque de la photopériode, la température, la densité de la population, la disponibilité de nourriture et la qualité de l'eau dans laquelle on garde les animaux. Toutefois le changement est transitoire et les animaux se reproduisent par parthénogenèse après un certain temps même gardés sous les conditions qui font au délut qu'ils se reproduisent sexuellement., On montre que pour Daphnia magna le changement de la parthénogenèse à la reproduction sexuelle est causé par l'action réciproque de la photopériode, la température, la densité de la population, la disponibilité de nourriture et la qualité de l'eau dans laquelle on garde les animaux. Toutefois le changement est transitoire et les animaux se reproduisent par parthénogenèse après un certain temps même gardés sous les conditions qui font au délut qu'ils se reproduisent sexuellement.]
1.1. Androgens and estrogens were injected into the body cavity of two species of the slug, Deroceras reticulatus and Limax ftavus.2.2. Estrogen stimulated egg-laying in spite of the low rate of development, whereas androgen enhanced the rate of development rather than the number of eggs laid.3.3. Removal of the optic tentacles in slugs followed by estrogen and androgen administration led to a higher rate of development and egg-laying.4.4. Administered together, estradiol and dehydroepiandrosterone enhanced the rate of both egg-lying and development.5.5. Since gonadotrophin treatment increased egg-laying and metopirone inhibited both the rate of egg-laying and development, it suggests regulation by steroid hormones of reproduction.6.6.The mechanism of hormonal regulation of reproduction in slugs seems to resemble that of the hypothalamo-hypophyseal-gonad system in vertebrates.
Steroid hydroxylase activities were characterized in Daphnia magna and evaluated for potential use as biomarkers of xenobiotic exposure. Microsomes prepared from Daphma magna generated a single NADPH-dependent metabolite of [14C]testosterone. However, intact daphnids excreted at least 10 polar metabolites of [l4C]testosterone into the test medium. Six of these metabolites were identified as 2-, 16β-, 6β-, 6-, 7-, and 15-[14C]hydroxytestosterone. The unidentified metabolites are also presumed to be hydroxylated products of testosterone, based on their relative migrations during TLC. The inefficient metabolism of [14C]testosterone during the in vitro microsomal incubations may have been due to the release of P450 inhibitors during microsome preparation. Exposure of daphnids to the P450 modulators phenobarbital, β-naphthoflavone, piperonyl butoxide, and malathion differentially inhibited the steroid hydroxylase activities. Results from this study indicate that Daphma magna expresses several P450 enzymes and that these enzymes are differentially modulated by xenobiotic exposure. Steroid hydroxylase activities may serve not only as a biomarker of toxicant exposure, but also as a predictor of toxicant effects involving perturbations of steroid hormone homeostasis.
A new rearing technique ideally suitable for promoting either the parthenogenetic or the gametogenetic (ephippia) type of reproduction ofDaphnia magna in the laboratory is described. Airdrying and rehydration induces rapid hatching. Using this technique it is possible to measure the toxicity of chemicals to ephippia in an 8 day test procedure.
Phase I and phase II chemical detoxication processes were elucidated in Daphnia magna using in vivo techniques and [14C]testosterone as a substrate. Testosterone was used because this compound undergoes multiple biotransformations and its metabolites are well characterized in other species. In addition, regulation of these processes by the endogenous steroid hormone, 20-hydroxyecdysone, was investigated. Daphnids produced at least ten polar phase I metabolites and four nonpolar phase I metabolites of testosterone. Six of the ten polar metabolites have been identified as monohydroxy-products of testosterone. The polar metabolites were preferentially excreted while the nonpolar metabolites were preferentially retained by the daphnids. In addition, testosterone and all phase I metabolites were also excreted as glucose conjugates. A polar metabolite designated ‘C’ was preferentially conjugated with glucose over the other metabolites. Testosterone and its polar phase I metabolites were also excreted as sulfate conjugates with 2α-hydroxytestosterone being the predominant sulfate-conjugated metabolite. In contrast to glucose conjugation, no nonpolar phase I metabolites of testosterone were sulfate conjugated. Twenty-four hour pre-exposure of daphnids to 4.2 μM 20-hydroxyecdysone did not affect phase I metabolism of testosterone, but differentially modulated phase II conjugation in a manner suggesting the presence of at least two glucosyltransferases and two sulfotransferases. Treatment with 20-hydroxyecdysone significantly increased the elimination of sulfate conjugates due largely to increased sulfate conjugation of unmetabolized testosterone. These results demonstrate that daphnids can convert polycyclic compounds to multiple polar and nonpolar metabolites resulting from both phase I and phase II biotransformations, and that some phase II activities are under the regulatory control of 20-hydroxyecdysone.
Many of the organochlorine pesticides have been shown to elicit estrogenic responses in laboratory animals. Two estrogenic actions, initiation of implantation and maintenance of pregnancy, were examined in progesterone-primed, delayed-implanting, hypophysectomized rats exposed to several polychlorinated hydrocarbons. The insecticide P,P'-dichlorodiphenyltrichloroethane (DDT) was nearly devoid of estrogenic activity for initiating implantation, as was a dichloro analog, 1,1-dichloro-2-[p-chlorophenyl],2-[o-chlorophenyl]ethane (O,P'-DDD), but another such analog, 1,1-dichloro-2-(p-chlorophenyl),2-(o-chlorophenyl)ethylene (O,P'-DDE), was nearly as estrogenic as the O,P'-DDT isomer of DDT and the methoxylated analog methoxychlor. The latter three compounds not only initiated implantation, but maintained pregnancy when given in large (200 mg/kg) and repeated doses. Another insecticide, chlordecone (Kepone) was more estrogenic than any of the DDT analogs and maintained pregnancy with a single dose of 50 mg/kg. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a toxic contaminant of herbicide production, did not induce implantation at a dose of 125 micrograms/kg, but inhibited the implantation initiated by estrone in 35% of the animals. The mechanism of this antiestrogenicity is unknown but most probably does not involve direct action via the classical estrogen receptor. The possible interference with the normal blastocyst-uterine interactions of these polychlorinated xenobiotics may be an important factor in their being considered reproductive toxins.
A series of polychlorinated hydroxybiphenyls (PCBs) has been tested for their binding activity to soluble uterine estrogen receptor protein. Competitive binding analysis was performed on 0-40% ammonium sulfate-enriched uterine cytosol receptor preparations which improved the binding activity for the PCB compounds by a factor of 10-40, by decreasing the nonspecific binding. The binding activities have been correlated to molecular properties supported by molecular modeling studies which emphasize the importance of conformational restriction. The estrogen receptor bound 4-hydroxy-2',4',6'-trichlorobiphenyl (4H2',4',6'TCB) with the greatest affinity, with the concentration of unlabeled inhibitor yielding half-maximal specific binding relative to estradiol (C50) being approximately 42 compared to estradiol, C50 approximately 1.0. PCB compounds that demonstrated appreciable receptor-binding activity were also active in vivo in stimulating uterine weight increases, whereas weak binders were inactive. The 4H2',4',6'TCB compound represents a high degree of conformational restriction around the interring bond due to the presence of two ortho-chlorine atoms. The other PCBs in this series, which show lower receptor-binding activity, vary in position of chlorine substituents and can assume multiple low energy conformations as a result of less hindrance to rotation around the interring bond.
Since estradiol has been detected in Bombyx ovaries effects of estradiol and other steroids on the growth and maturation of the silkworm ovary, rate of oviposition, and embryonic development were examined as a part of a study aimed at the clarification of physiological significance of estradiol in insects. These steroids were injected at various doses into the whole pupae and into the isolated pupal abdomens. No significant effect by the injections was observed on the ovarian development, as judged by increase in protein content or wet weight of ovaries and pattern of protein constituents including vitellin. However, rate of oviposition was considerably affected by the injection of estradiol at high doses. No clear effect was observed on embryonic development or determination of diapause by the injection of estradiol into the pupae. Effects of injection of anti-estrogen, nafoxidine, into the isolated abdomens and whole pupae were also examined. No effects were observed on ovarian development by injection. The relationship between physiological significance of the vertebrate steroids and metabolic activity of the ovary is discussed.
Estradiol was extracted and partially purified from the ovaries of the silkworm, Bombyx mori. Identification of estradiol was done by use of radioimmunoassay (RIA) and by gas chromatography-mass spectrometry (GC-MS) after derivatization into the ethyldimethylsilyl derivative. Concentration of estradiol in the ovaries was estimated to be 176 pg/g (RIA) and 63 pg/g (GC-MS).
In vitro biosynthesis of steroids from androstenedione in ovaries and pyloric caeca of Asterias rubens has been investigated. The formation of testosterone and 5α-androstane-3,17-dione has been demonstrated for tissues of both organs by using [7(n)-3H]androstenedione as a precursor; no evidence was obtained for the synthesis of oestrogens.Testosterone is produced in large quantities; the yields of this steroid are higher in the pyloric caeca than in the ovaries. In contrast 5α-androstane-3,17-dione is synthesized in large quantities in the ovaries and in small quantities in the pyloric caeca. The results indicate the biosynthetic enzymes 17β-HSD and 5α-reductase to be present in ovaries and pyloric caeca of Asterias rubens; the presence of an aromatization enzyme complex could not be demonstrated. The importance of these enzymes for the androstenedione metabolism as well as a scheme summarizing the steroid biosynthesis of Asterias rubens known so far will be discussed.
The terrestrial snail, Euhadra peliomphala, has a peculiar organ between the optic tentacles named the head-wart, which releases a sex pheromone just before courtship. The development of the head-wart was closely correlated with the sexual maturity of the snail. Castration led to the atrophy of the head-wart. Subsequent injection of hermaphrodite gland homogenate into the body cavity of castrated individuals induced the development of the head-wart. The peripheral regions of the acini in the hermaphrodite gland showed a positive reaction for 3 beta-hydroxy steroid dehydrogenase. Furthermore, preliminary radioimmunoassay also showed that the hermaphrodite gland of the snail contained testosterone and estradiol. When the immature head-wart was cultured for 10 days in a medium containing testosterone and estradiol respectively, development of the head-wart was found only in medium containing testosterone. From these results, it is concluded that head-wart development in the snail, Euhadra peliomphala, is under direct control from the hermaphrodite gland, probably by means of testosterone.
The incidence of disorders of development of the male reproductive tract has more than doubled in the past 30-50 years while sperm counts have declined by about half. Similar abnormalities occur in the sons of women exposed to diethylstilbestrol (DES) during pregnancy and can be induced in animals by brief exposure to exogenous oestrogen/DES during pregnancy. We argue that the increasing incidence of reproductive abnormalities in the human male may be related to increased oestrogen exposure in utero, and identify mechanisms by which this exposure could occur.
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