Non-traditional targets of endocrine disrupting chemicals: the roots of hormone signaling

The topic of endocrine disruption and the broad range of physiologicaleffects caused by endocrine disrupting chemicals (EDCs) canonly be meaningfully framed within an ecological and evolutionarycontext. Environmental pollutants and EDCs operate by disruptingthe "chemical communication" that coordinates signaling withinan organism. Here we discuss how EDCs are also able to disruptthe chemical communication between plants and soil bacterianecessary for initiating nitrogen-fixing symbiosis. We alsoexamine, through examples of pollutant-related impacts on awide range of invertebrates, the need for identifying emergingtargets of EDCs. We suggest broadening the defined field ofendocrine disruption to encompass the effects of synthetic chemicalsthat interfere with signaling and communication, not only withinan organism, but also between organisms and linking ecosystems.The ecological consequences of failing to recognize novel targetsof chemical pollutants and EDCs may be a net loss of biologicaldiversity and a further imbalance of the global nitrogen cycle.     

Prediction,docking study and molecular simulation of 3D DNA aptamers to their targets of endocrine disrupting chemicals

Abstract

Typical endocrine disrupting chemicals, including BPA (Bisphenol A), E₂ (17-β-Estradiol) and PCB 72 (polychlorinated biphenyl 72), are commonly and widely present in the environment with good chemical stability that are difficult to decompose in vitro and in vivo. Most of the high-qualified antibodies are required as the key biomaterials to fabricate the immunosensor for capturing and detecting. As an ideal alternative, the short-chain oligonucleotides (aptamer) are essentially and effectively employed with the advantages of small size, chemical stability and high effectiveness for monitoring these environmental contaminants. However, the molecular interaction, acting site and mode are still not well understood. In this work, we explored the binding features of the aptamers with their targeting ligands. The molecular dynamics simulations were performed on the aptamer–ligand complex systems. The stability of each simulation system was evaluated based on its root-mean-square deviation. The affinities of these proposed ligands and the predicted binding sites are analyzed. According to the binding energy analysis, the affinities between ligands and aptamers and the stability of the systems are BPA?>?PCB 72 >E₂. Trajectory analysis for these three complexes indicated that these three ligands were able to steadily bind with aptamers at docking site from 0 to 50?ns and contributed to alteration of conformation of aptamers.     

Neuroendocrine and behavioral implications of endocrine disrupting chemicals in quail

Studies in our laboratory have focused on endocrine, neuroendocrine, and behavioral components of reproduction in the Japanese quail. These studies considered various stages in the life cycle, including embryonic development, sexual maturation, adult reproductive function, and aging. A major focus of our research has been the role of neuroendocrine systems that appear to synchronize both endocrine and behavioral responses. These studies provide the basis for our more recent research on the impact of endocrine disrupting chemicals (EDCs) on reproductive function in the Japanese quail. These endocrine active chemicals include pesticides, herbicides, industrial products, and plant phytoestrogens. Many of these chemicals appear to mimic vertebrate steroids, often by interacting with steroid receptors. However, most EDCs have relatively weak biological activity compared to native steroid hormones. Therefore, it becomes important to understand the mode and mechanism of action of classes of these chemicals and sensitive stages in the life history of various species. Precocial birds, such as the Japanese quail, are likely to be sensitive to EDC effects during embryonic development, because sexual differentiation occurs during this period. Accordingly, adult quail may be less impacted by EDC exposure. Because there are a great many data available on normal development and reproductive function in this species, the Japanese quail provides an excellent model for examining the effects of EDCs. Thus, we have begun studies using a Japanese quail model system to study the effects of EDCs on reproductive endocrine and behavioral responses. In this review, we have two goals: first, to provide a summary of reproductive development and sexual differentiation in intact Japanese quail embryos, including ontogenetic patterns in steroid hormones in the embryonic and maturing quail. Second, we discuss some recent data from experiments in our laboratory in which EDCs have been tested in Japanese quail. The Japanese quail provides an excellent avian model for testing EDCs because this species has well-characterized reproductive endocrine and behavioral responses. Considerable research has been conducted in quail in which the effects of embryonic steroid exposure have been studied relative to reproductive behavior. Moreover, developmental processes have been studied extensively and include investigations of the reproductive axis, thyroid system, and stress and immune responses. We have conducted a number of studies, which have considered long-term neuroendocrine consequences as well as behavioral responses to steroids. Some of these studies have specifically tested the effects of embryonic steroid exposure on later reproductive function in a multigenerational context. A multigenerational exposure provides a basis for understanding potential exposure scenarios in the field. In addition, potential routes of exposure to EDCs for avian species are being considered, as well as differential effects due to stage of the life cycle at exposure to an EDC. The studies in our laboratory have used both diet and egg injection as modes of exposure for Japanese quail. In this way, birds were exposed to a specific dose of an EDC at a selected stage in development by injection. Alternatively, dietary exposure appears to be a primary route of exposure; therefore experimental exposure through the diet mimics potential field situations. Thus, experiments should consider a number of aspects of exposure when attempting to replicate field exposures to EDCs.     

Direct action of endocrine disrupting chemicals on human sperm

Synthetic endocrine disrupting chemicals (EDCs), omnipresent in food, household, and personal care products, have been implicated in adverse trends in human reproduction, including infertility and increasing demand for assisted reproduction. Here, we study the action of 96 ubiquitous EDCs on human sperm. We show that structurally diverse EDCs activate the sperm‐specific CatSper channel and, thereby, evoke an intracellular Ca²⁺ increase, a motility response, and acrosomal exocytosis. Moreover, EDCs desensitize sperm for physiological CatSper ligands and cooperate in low‐dose mixtures to elevate Ca²⁺ levels in sperm. We conclude that EDCs interfere with various sperm functions and, thereby, might impair human fertilization.     

内分泌干扰物中毒机理探析

叙述了内分泌干扰物(EDC)的类型及危害,讨论了活性氧在内分泌干扰物环境毒理学的相关定义,并进一步解释了活性氧所引起的中毒机理。     

The immunotoxicity of environmental contaminants to marine wildlife: A review

Virus-associated mass mortalities among several marine mammal populations inhabiting industrialized coastal areas have generated an interest in wildlife immunotoxicology. Despite the isolation of previously uncharacterized viruses from victims, a contribution of immunotoxic contaminants to the severity of the outbreaks could not be ruled out. Fish-eating marine mammals, including seals, occupy high trophic levels in the aquatic food chain, and accumulate high levels of contaminants including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychorinated dibenzofurans (PCDFs). Such chemicals have been found to be immunotoxic at low doses in studies of laboratory animals. While associations have been established between environmental contaminants and various adverse biological effects in certain free-ranging seal populations, evidence for immunotoxicity has, until recently, been lacking. To this end, we carried out an immunotoxicological study, in which captive harbor seals were fed herring from either relatively uncontaminated sites of the Atlantic Ocean, or from the highly contaminated Baltic Sea. In this review, we summarize the contaminant-related immunosuppression observed in the captive group of seals fed herring from the Baltic Sea, and discuss these results in the context of what is currently known about outbreaks of virus infection, comparative immunology, and environmental contaminants. We also describe two parallel studies, in which laboratory rats exposed as adults or perinatally to the contaminants in the Baltic Sea herring, exhibited immunotoxicity. On the basis of these and other studies, we conclude that complex mixtures of environmental contaminants may represent a real immunotoxic risk to free-ranging marine mammals in many areas of Europe and North America.     

Molecular targets for disrupting leukocyte trafficking during multiple sclerosis

Autoimmune diseases of the central nervous system (CNS) involve the migration of abnormal numbers of self-directed leukocytes across the blood-brain barrier that normally separates the CNS from the immune system. The cardinal lesion associated with neuroinflammatory diseases is the perivascular infiltrate, which comprises leukocytes that have traversed the endothelium and have congregated in a subendothelial space between the endothelial-cell basement membrane and the glial limitans. The exit of mononuclear cells from this space can be beneficial, as when virus-specific lymphocytes enter the CNS for pathogen clearance, or might induce CNS damage, such as in the autoimmune disease multiple sclerosis when myelin-specific lymphocytes invade and induce demyelinating lesions. The molecular mechanisms involved in the movement of lymphocytes through these compartments involve multiple signalling pathways between these cells and the microvasculature. In this review, we discuss adhesion, costimulatory, cytokine, chemokine and signalling molecules involved in the dialogue between lymphocytes and endothelial cells that leads to inflammatory infiltrates within the CNS, and the targeting of these molecules as therapies for the treatment of multiple sclerosis.     

外因性内分泌干扰物质对人类的危害及预防

论述了外因性内分泌干扰物质是环境中的激素类似物,它能通过与激素受体结合,干扰正常的生理代谢、内分泌、生殖机能,引起种种负面的生物学效应,同时提出了对外因性内分泌干扰物质的控制和预防措施。     

Identification of an endocrine disrupting agent from corn with mitogenic activity

A mitogenic agent in corncob bedding and fresh corn products disrupts sexual behavior and estrous cyclicity in rats. The mitogenic activity resides in an isomeric mixture of linoleic acid derivatives with a tetrahydrofuran ring and two hydroxyl groups (THF-diols) that include 9, (12)-oxy-10,13-dihydroxystearic acid and 10, (13)-oxy-9,12-dihydroxystearic acid. Synthetic THF-diols stimulated breast cancer cell proliferation in vitro and disrupted the estrous cycle in female rats at oral doses of approximately 0.30 mg/kg body weight/day. Exposure to THF-diols may disrupt endocrine function in experimental animals at doses approximately 200 times lower than classical phytoestrogens, promote proliferation of breast or prostate cancer, and adversely affect human health.     

Projecting population-level responses of mysids exposed to an endocrine disrupting chemical

To fully understand the implications of a chemical's effecton the conservation of a species, effects observed at the physiologicalor individual level must be expressed in terms of the population.Since long-term field experiments are typically not feasible,vital rates such as survival and reproduction of individualorganisms are measured in life table response experiments (LTRE)and employed to extrapolate the effects of a pollutant on thepopulation. The population-level response of the mysid, Americamysisbahia, to varying concentrations of methoprene (0, 4, 8, 16,31, 62 µg/L) was determined using age-structured populationmodels. Models were parameterized from the results of an LTREconducted throughout the entire mysid life cycle. A density-independentmatrix model with time invariant demographic parameters wasdeveloped to measure the change in population growth rate, ,with change in methoprene concentration. The values of weregreater than one for all methoprene concentrations, indicatingthat populations exposed to the concentrations reported herewould not become extinct. However, a general decrease in occurredwith increasing methoprene concentration and would result inreduced population sizes. Sensitivity and decomposition analyseswere conducted to determined the relative roles of the vitalrates on altered population growth rates and determined thatimpaired reproduction was the primary influence on the observeddecrease in . The model constructed was a useful tool for linkingthe individual-level effects to the population-level consequencesof methoprene exposure on mysids, as well as defining the mechanism(reduced reproduction) responsible for the observed effectson population.     

Luminescent yeast cells entrapped in hydrogels for estrogenic endocrine disrupting chemical biodetection

In the construction of luminescent yeast cell based fibre-optic biosensors, we demonstrate a novel approach for estrogenic endocrine disrupting chemical (EDC) biodetection by entrapping genetically modified Saccharomyces cerevisiae cells, containing the estrogen receptor alpha-mediated expression of the luc reporter gene, in hydrogel matrices based on calcium alginate or PVA. In order to insure a significant signal, an optimal immobilization ratio of 1:2 alginate 3% (w/v): 5 × 10⁶ [cells/ml], respectively, was used with the highest 17-β-estradiol (β-E2) induction factor after 2.5 h of incubation with 10 [nM] β-E2. It was shown that biocompatible alginate beads, 4.27–4.55 × 10⁵ [CFU/bead], which were characterized by a detection limit of 0.08 [μg l⁻¹] and an EC50 of 0.64 [μg l⁻¹] for β-E2, retained their viability for luminescence measurements after 1 month of storage at −80 °C slow freeze condition, and thus repeated cell cultivations were not required. The assay reproducibility for each tested EDC, represented by the coefficients of variation (CV), ranged from 4.35 to 18.47%. An alternative immobilization method, based on a room temperature partial drying of polyvinyl alcohol (PVA) solution (LentiKat^® Liquid) and cell suspension mix, was investigated with only a slightly lower detection limit for β-E2 than that reported with alginate beads. Alginate yeast based hydrogels may also be applicable to the analysis of environmental water samples since the trend of detected estrogenic activities with alginate beads roughly correlated with LC–MS–MS analytical results.     

Environmental biosensors for organochlorines, cyanobacterial toxins and endocrine disrupting chemicals

Environmental biosensors and related techniques for monitoring organochlorines, endocrine disrupting chemicals and cyanobacterial toxins are described. The practical requirements for an ideal environmental biosensor are analyzed. Specific case studies for environmental applications are reported for triazines chlorinated phenols, PCBs, microcystins, and endocrine disrupting chemicals. A new promising approach is reported for microcystins and alkylphenols that utilize electrooptical detection.     

Enhanced expression of laccase during the degradation of endocrine disrupting chemicals in Trametes versicolor

A putative laccase cDNA from a white-rot basidiomycete, Trametes versicolor, that consisted of 1,769 nucleotides was cloned using the rapid amplification of cDNA ends (RACE)-PCR method. The deduced amino acid sequence had 4 putative copper binding regions, which are common to fungal laccases. In addition, the sequence was 57 approximately 97 % homologous to sequences of other T. versicolor laccases. Additionally, the expression of laccase and manganese peroxidase in this fungus were both greatly increased under degrading conditions for bisphenol A, nonylphenol and two phthalic esters (benzylbutylphthalate and diethylphthalate), all of which are reportedly endocrine disrupting chemicals (EDCs). Furthermore, the estrogenic activities of the EDCs also decreased rapidly during incubation when examined in a two-hybrid yeast system. Finally, kojic acid inhibited the removal of estrogenic activities generated by bisphenol A and nonylphenol, which confirmed that laccase was involved in the degradation of EDCs in T. versicolor.     

Characterization of Hsp70 gene in Chironomus riparius: expression in response to endocrine disrupting pollutants as a marker of ecotoxicological stress

We characterized the Hsp70 cDNA in Chironomus riparius and evaluated its expression profile under different environmental stressors. It is highly conserved, at both DNA and protein levels, displaying many of the hallmarks of Hsps and sharing 80-96% of overall amino acid identities with homologous sequences from other diptera. The changes are mainly concentrated in the C-terminal domain of the protein. Phylogenetic analysis was consistent with the known classification of insects. The Hsp70 gene was located by in situ hybridization in region III-3A at the third polytene chromosome, a locus activated upon heat shock as shown by RNA pol II binding. As C. riparius is widely used in aquatic ecotoxicology testing, we studied Hsp70 gene induction in fourth instar aquatic larvae submitted to heat shock and selected environmental pollutants classified as potential endocrine disruptors. RT-PCR analysis showed that Hsp70 mRNA levels increased significantly (p<0.05) after short-term acute exposures to a temperature shift (HS), cadmium chloride (Cd), butyl benzyl phthalate (BBP), diethylhexyl phthalate (DEHP), bisphenol A (BPA), 4-nonylphenol (NP) and ethinylestradiol (EE). However, neither pentachlorophenol (PCP) nor tributyltin (TBTO) treatments were able to activate the Hsp70 gene. The cognate form, Hsc70, was also analysed and, unlike Hsp70, was not altered by any of the different treatments assayed. Moreover, at the times tested, there was no significant mortality of the larvae. The rapid upregulation of the Hsp70 gene suggests that it is sensitive and selective for different environmental pollutants, and could be used as an early molecular endpoint in ecotoxicological studies.