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1.
Recent studies have shown that several environmental chemicals which disrupt classical genomic steroid actions can also interfere with nongenomic steroid actions initiated at the cell surface. The effects of bisphenol-A and atrazine on the nongenomic actions of a progestin, 17,20 beta,21-trihydroxy-4-pregnen-3-one (20 beta-S), on oocyte maturation (OM) were investigated an in vitro Atlantic croaker (Micropogonias undulatus) oocyte bioassay. Treatment of croaker follicle-enclosed oocytes with either bisphenol-A or atrazine blocked OM in response to 20 beta-S in a concentration-dependent manner at 10-25 microM (2.2-5.7 ppm) and higher concentrations. These compounds were also effective competitors at concentrations of 10(-6)-10(-5)M of [3H]-20 beta-S binding to the ovarian progestin membrane receptor that mediates the OM response to 20 beta-S. The results suggest that diverse classes of environmental chemicals can disrupt nongenomic progestin actions via receptor-mediated mechanisms. 相似文献
2.
Environmental chemicals may modulate the endocrine system through interaction with plasma sex steroid-binding proteins (SBP) and SBP-regulated processes. Some of these chemicals, which are known to interact with the estrogen receptor (ER), were found to bind competitively to the Atlantic salmon (Salmo salar) SBP and potentially disrupt the endocrine function of these proteins. Furthermore, both weakly acting (di-n-butyl phthalate) and potent estrogen mimics (ethynylestradiol), were able to induce a substantial up-regulation of circulating levels of SBP in vivo. Interestingly, modulation of SBP-levels was found to be a more sensitive endpoint than chemically induced interference with classical ER-mediated mechanisms for weakly acting estrogen mimics like di-(n-butyl) phthalate. Interference with the endocrine function of SBPs may thus introduce a novel mechanism for endocrine disruption. and give additional answers to the question why some weakly acting xenoestrogens are causing "estrogen-like" reproductive disturbances in developing males. 相似文献
3.
Knut-Erik Tollefsen Joris F. A. Meys Jorid Frydenlund Jrgen Stenersen 《Marine environmental research》2002,54(3-5)
Environmental chemicals may modulate the endocrine system through interaction with plasma sex steroid-binding proteins (SBP) and SBP-regulated processes. Some of these chemicals, which are known to interact with the estrogen receptor (ER), were found to bind competitively to the Atlantic salmon (Salmo salar) SBP and potentially disrupt the endocrine function of these proteins. Furthermore, both weakly acting (di-n-butyl phthalate) and potent estrogen mimics (ethynylestradiol), were able to induce a substantial up-regulation of circulating levels of SBP in vivo. Interestingly, modulation of SBP-levels was found to be a more sensitive endpoint than chemically induced interference with classical ER-mediated mechanisms for weakly acting estrogen mimics like di-(n-butyl) phthalate. Interference with the endocrine function of SBPs may thus introduce a novel mechanism for endocrine disruption, and give additional answers to the question why some weakly acting xenoestrogens are causing “estrogen-like” reproductive disturbances in developing males. 相似文献
4.
The antagonistic effects of Kepone (chlordecone) and o,p'-DDD on maturation-inducing steroid (17α,20β,21-trihydroxy-4-pregnen-3-one, 20β-S) induced final maturation of Atlantic croaker (Micropogonias undulatus). Oocytes were investigated in an in vitro germinal vesicle breakdown (GVBD) bioassay. Exposure to Kepone or o,p'-DDD (100 nM-100 μM) prevented the majority of the oocytes from completing GVBD in response to 20β-S; many of them were arrested at the lipid coalescence or germinal vesicle migration stages when exposed to high xenobiotic concentrations (100 μM). In addition, clearing of the ooplasm, oil droplet formation and hydration were incomplete in xenobiotic-exposed oocytes that underwent GVBD. The xenobiotics inhibited GVBD in a concentration-dependent manner. One minute exposure to either of the xenobiotics was sufficient to block GVBD. Washing the follicle-enclosed oocytes after xenobiotic exposure restored their ability to undergo GVBD in response to 20β-S. These results suggest that o,p'-DDD and Kepone exert antagonistic effects on 20β-S action, possibly by competing for the ovarian 20β-S membrane receptor. 相似文献
5.
Peter Thomas 《Marine environmental research》1988,24(1-4)
To examine whether xenobiotics impair teleost reproduction by altering reproductive endocrine function, steroid hormone secretion and ovarian growth were investigated in female Atlantic croaker (Micropogonias undulatus) after chronic oral administration with sublethal doses of three classes of reproductive toxins (lead, benzo[a]pyrene and Aroclor 1254). All the sublethal treatments significantly impaired ovarian growth as assessed by the gonadosomatic index. Reduced ovarian growth was accompanied by a significant decline in circulating 17β-estradiol levels in fish exposed to lead and benzo[a]pyrene. All three toxicants significantly decreased plasma testosterone levels. However, the steroidogenic capacity of ovarian tissue in vitro was not altered by xenobiotic exposure. The data suggest that the decreased ovarian growth in croaker after pollutant exposure may be a consequence of the decline in plasma 17β-estradiol levels. Further, this decrease in circulating levels of gonadal steroids does not appear to be caused by a direct effect of the chemicals on ovarian steroid synthesis. 相似文献
6.
运用免疫组织化学和化学发光免疫分析方法研究了皱瘤海鞘(Styela plicata)神经递质多巴胺(DA)、5-羟色胺(5-HT)及其受体以及性类固醇激素含量与性腺发育成熟的关系.结果显示,DA和5-HT免疫活性定位在脑神经节中大小2种类型的神经细胞,DA免疫活性还定位在不同发育时期神经腺上皮细胞.5-HT受体免疫活性存在于脑神经节小型神经细胞和大生长期神经腺上皮细胞.在小生长期和大生长期性腺中均检测到DA、5-HT及其受体,提示DA和5-HT可能参与调节皱瘤海鞘的性腺发育.皱瘤海鞘为雌雄同体,化学发光免疫分析证实,海鞘性腺能够合成和分泌性类固醇激素,大生长期性腺中雄激素、孕激素和雌激素的含量分别为25.8±0.0、38.9±0.2和14.3±0.6pg/mg,提示性腺既是生殖组织也是内分泌组织.上述发现为证明尾索类海鞘可能像头索类文昌鱼一样,具有原始的生殖内分泌调控轴(脑神经节-神经腺-性腺)提供科学依据. 相似文献
7.
促性腺激素释放激素(GnRH)是1种在下丘脑-垂体-性腺轴(Hypothalamus-pituitary-gonad,HPG)的活动中发挥关键作用的神经激素。研究采用染色体步移方法,从许氏平鲉的肌肉组织中克隆得到GnRH1、GnRH2和GnRH3共3个基因的启动子序列,长度分别为4,3.5和2.5kb。利用在线生物信息学软件对这3个GnRH基因的启动子进行预测分析,结果表明,3个基因均存在Sp1,Oct-1,C/EBP,CREB,Pit-1,NF-1,Brn,GATA-1,USF和MyoD等转录因子的结合位点,以及糖皮质激素受体(GR),雄激素受体(AR),雌激素受体(ER),黄体酮受体(PR),视黄酸受体(RAR)和视黄醇受体(RXR)等核受体的结合位点,推测其对GnRH的调控起到关键作用。但是甲状腺激素受体(TR)和嗅觉相关的Olf-1的结合位点只在GnRH1和GnRH2基因启动子中发现,而在GnRH3中没有预测出。本研究结果表明许氏平鮋不同类型的GnRH是受不同的机制调控的,从而在生理过程中发挥着不同的作用。 相似文献
8.
Several environmentally relevant contaminants are characterized as xenoestrogens by virtue of their ability to induce responses similar to 17β-estradiol (E2). There is concern that exposure to these xenoestrogens may result in endocrine and, thus, reproductive disruption. The objective of the present research was to determine whether xenobiotics known to elicit estrogenic responses in mammals were estrogenic in channel catfish, and if these compounds were capable of altering normal physiological response to E2. Sexually immature catfish were exposed by intraperitoneal injection to E2, suspected xenoestrogens or combination doses of E2 and xenoestrogen. Appearance of vitellogenin (Vg) in serum was used as the bioindicator of estrogenicity; Vg was measured by ELISA 7 days after injection. The ED50 of E2 for the appearance of Vg in blood, 0.6 mg/kg, was used as the positive control. Synthetic estrogens, ethinylestradiol, mestranol and DES were effective in inducing Vg; the antiestrogen tamoxifen inhibited response to E2 when given in a combination dose. Treatment by both methoxychlor and p-nonylphenol resulted in Vg appearance in serum; the doses required were 300 times that of E2, and the vitellogenic response was less when compared to the E2-induced response. In addition, a combination dose of methoxychlor with E2 decreased the magnitude of the response to E2. Other mammalian xenoestrogens, o,p′-DDT, chlordecone, lindane and β-HCH, were not able to produce a vitellogenic response in this study. 相似文献
9.
Estrogenic effect of dioxin-like aryl hydrocarbon receptor (AhR) agonist (PCB congener 126) in salmon hepatocytes 总被引：1，自引：0，他引：1
Previous studies have shown that aryl hydrocarbon receptor (AhR) agonists possess anti-estrogenic activities and several mechanisms have been proposed to explain the interactions between AhR and estrogen receptor (ER) signalling pathways. In the present study, we show that 3,3'4,4'5-pentachlorobiphenyl (PCB126 - a dioxin-like AhR agonist) produced estrogenic responses in the absence of ER agonist, in fish in vitro system. We exposed salmon primary hepatocytes to PCB126 (1, 10 and 50 pM) and the ER agonist nonylphenol (NP; 5 and 10 microM) singly and also in combination. Vitellogenin (Vtg) and zona radiata proteins (Zr-proteins) levels were analysed by semi-quantitative ELISA. We observed that the protein levels of Vtg and Zr-proteins were significantly induced in a concentration-specific manner in cells treated with PCB126 and NP, singly or in combination. In general, these results show a novel aspect of dioxin-like PCB effect not previously demonstrated in fish system. 相似文献
10.
D. Schlenk D. M. Stresser J. Rimoldi L. Arcand J. McCants A. C. Nimrod W. H. Bensorr 《Marine environmental research》1998,46(1-5)
Methoxychlor (MXC) has been shown to possess estrogenic activity in mammals and fish. Although MXC does not appear to appreciably bind the mammalian estrogen receptor, its demethylated metabolites have been shown to be significantly more potent agonists and are believed responsible for estrogenic effects in mammals following exposure to this pesticide. To determine whether catfish were capable of MXC demethylotion, and, hence, activation to a more estrogenic compound, in vitro biotransformation studies were carried out using hepatic microsomes from mature male channel catfish. Hepatic microsomes catalyzed the NADPH-dependent formation of monodemethylated (mono-MXC) and bisdemethylated (bis-MXC) metabolites of MXC. Treatment with mono-MXC at 40% of the MXC dose in catfish significantly induced serum vitellogenin (Vg) levels compared to MXC. Estrogen receptor binding studies in catfish liver cytosol showed that a racemic mixture of the mono-MXC had approximately 43 times the affinity for the receptor than MXC, but was still over 1000-fold less potent that 17β-estradiol. These results demonstrate that catfish are capable of biochemically activating MXC to a more potent hepatic estrogen receptor agonist. 相似文献
11.
David A Dagnino S Pichot Y Munaron D Escande A Casellas C Fenet H Gomez E 《Marine environmental research》2008,66(1):105-107
In vitro bioassays would facilitate monitoring of estrogen-like compounds in mussels (Mytilus galloprovincialis) since they tend to accumulate lipophilic compounds in their fat and muscle tissue. However, estradiol (E2) steroid (already identified in mussels) could induce false positive responses. This study focuses on temporal variability in estrogenic responses of mussel extracts and the possible relation of this response with E2 levels. The reproductive cycle and growth were thus monitored for six months in sexed mussels. E2 levels were similar between genders and these levels varied with reproductive stages. human estrogen receptor (hER) activities were similar at all stages except in February. E2 present in male and female extracts accounted for part of the hER activation observed, but no correlation was found between E2 levels and hER activities. 相似文献
12.
Since the brain plays important roles in reproduction, the brain aromatase (Cyp19b), estrogen receptor (ER), retinoid X receptor (RXR) α and peroxisome proliferator-activated receptor γ were examined in rockfish after TBT exposure (1, 10, and 100 ng L−1). The results showed that the Cyp19b expression was elevated in the male rockfish, while no effect was produced in the females. Inconsistently, serum testosterone and 17β-estradiol showed no change in the males, while an increase of testosterone and a decrease of 17β-estradiol were observed in the females. TBT affected the ER expression in the males depending on the concentrations, however, no change was observed in the females. In addition, TBT elevated the RXRα expression in the males but produced an opposite effect in the females. In conclusion, TBT might have had sex-different effects on the brain Cyp19b, ER and RXR expression in rockfish, indicating a complex endocrine disrupting effect of TBT. 相似文献
13.
14.
化学防御系统是生物抵御环境中化学胁迫和维持内环境稳态的重要机制,由长期进化出的一系列基因家族、蛋白和相关反应通路组成。该系统的核心组分包括:(1)受体和配体激活转录因子,其负责感知有毒化合物;(2)生物转化酶,其通过氧化、还原和结合反应使有毒物质的毒性降低,增加亲水性,使化合物更易排出;(3)外排转运蛋白,其负责将外源物质或生物转化产生的代谢物排出细胞;(4)抗氧化酶,其作用是保护细胞免受外部和内部产生的活性氧或自由基的伤害。本综述对动物化学防御系统的组成及作用机制进行概述,为研究海洋无脊椎动物的化学防御系统提供参考。 相似文献
15.
We have cloned the proto-oncogene c-fos from a self-fertilizing fish Rivulus marmoratus (Cyprinodontiformes, Rivulidae) after screening of R. marmoratus lambdaGEM-11 genomic DNA library, and sequenced over 12 kb including all exons, introns and the promoter region. The R. marmoratus c-fos gene consisted of one noncoding exon and four exons with high similarity to those of fugu and mammals. We sequenced approximately 7 kb of the R. marmoratus c-fos gene promoter region to gain a better understanding of the molecular anatomy of the immediate response of this gene upon cellular damage. In the promoter region, R. marmoratus c-fos gene has seven xenobiotic response elements (XREs) and eight metal response elements (MREs) as well as two estradiol (E2), 4 NFkappaB, 2 CarG, 2 prolactin (PRL) motifs and one pit1 site, while the 3'-UTR of this gene contains the estrogen response element (ERE). The seven XRE and eight MRE motifs raise the possibility of its regulation by exposure to environmental pollutants. In this paper, we discuss the gene structure of R. marmoratus c-fos gene and compare its promoter region with those of other organisms' c-fos genes. We propose its potential use in ecotoxicology. 相似文献
16.
This paper discusses the results of theoretical and experimental analysis of physical and physicochemical interactions in
the ‘membrane gauge-medium’ system. The principal parameters of the system affecting measurement of the chemical field parameters
under various conditions of overflow are identified. Simple computational formulae have been derived which are relevant for
engineering purposes and for treatment of the observed data.
Translated by Vladimir A. Puchkin. 相似文献
17.
C A Godard M J Leaver M R Said R L Dickerson S George J J Stegeman 《Marine environmental research》2000,50(1-5):7-10
The cytochromes P450 (CYP) constitute a multigene family of enzymes playing a critical role in the oxidation of many endogenous and xenobiotic substrates. The CYP1 family is of particular interest in environmental toxicology because its members are dominant in the metabolism of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and aryl amines. Three members of the CYP1 family, CYP1A1, CYP1A2, and CYP1B1, have been identified in mammals. We report here on the identification and cloning of cytochrome P4501B-like sequences from two teleost fish species and a marine mammal. Sequences clustering with CYP1B1 in phylogenetic analysis were obtained from liver cDNA of scup (Stenotomus chrysops), genomic DNA of plaice (Pleuronectes platessa), and liver cDNA of striped dolphin (Stenella coeruleoalba). 相似文献
18.
我国是全球最大的大黄鱼养殖国和出口国。为提升我国大黄鱼的产业发展和国际贸易水平,文章分析我国大黄鱼的出口贸易结构,分别采用显性比较优势指数、出口产品质量升级指数和贸易竞争力指数分析我国大黄鱼的国际竞争力,并在分析影响因素的基础上提出建议。研究结果表明:2008—2017年我国大黄鱼的出口规模总体稳定,出口额增长,出口量下降;我国大黄鱼的出口市场集中在亚洲国家和地区;我国大黄鱼的比较优势极强但正在减弱,以出口价格反映的产品质量偶有下降但总体提升,相对于国际市场同种产品的竞争优势较强,总体来看国际竞争力较高,但仍有提升的空间;影响我国大黄鱼出口贸易结构和国际竞争力的因素主要包括地区饮食习惯、相关行业发展、国际贸易壁垒和产业发展空间,未来我国大黄鱼的生产和贸易应充分发挥产业比较优势、合理规划产业发展空间、积极开拓新兴出口市场和有效应对国际贸易壁垒。 相似文献
19.
大黄鱼是我国近海主要的经济鱼类之一。为促进我国大黄鱼产业的可持续发展,文章从产业集聚的角度研究大黄鱼产业的发展规律,采用区位熵和空间基尼系数方法测度2011—2020年大黄鱼养殖产业和捕捞产业的集聚水平。研究结果表明：根据空间基尼系数的测算结果,大黄鱼养殖产业的集聚水平高于其捕捞产业;福建大黄鱼养殖产业的集聚水平相对于浙江和广东而言最高,但呈现下降趋势,浙江大黄鱼养殖产业的集聚水平呈现上升趋势,目前已高于全国平均水平,广东大黄鱼养殖产业的集聚水平较低且基本维持稳定;大黄鱼捕捞产量较少,产业集聚水平相对不高,主要集中在辽宁、广东和海南,其中辽宁大黄鱼捕捞产业的区位熵呈现下降趋势,广东整体呈现上升趋势,海南基本维持稳定,福建、山东、江苏、浙江和上海等捕捞区域的产业集聚水平较低。基于研究结果并结合实地调研情况提出3点建议：加强大黄鱼养殖和加工等技术研究;政府完善并实施相关渔业法规,增加对养殖户的培训,提升大黄鱼品质;保护大黄鱼种质资源。 相似文献
20.
Todorov JR Elskus AA Schlenk D Ferguson PL Brownawell BJ McElroy AE 《Marine environmental research》2002,54(3-5):691-695
To determine the estrogenicity of effluents from sewage treatment plants (STPs) to larval fish, 2-day-old sunshine bass were exposed to effluents from three STPs serving New York City (NYC), varying in size and treatment level. Estrogenic response was evaluated by measuring vitellogenin (VTG) and estrogen receptor (ER) expression in cytosolic fractions of whole body homogenates. Concentrations of the presumptive endocrine disruptors in the effluents were also measured. VTG and ER levels in sewage-exposed fish were 3-5 times that observed in controls. Combined concentrations of estradiol and estrone ranged from 5 to 13 ng/l and nonylphenol-ethoxylate metabolites (NPEOs: 4-nonylphenol, and 1-, 2-, and 3-nonylphenol-ethoxylates) ranged from 180 to 470 microg/l in chlorinated effluent. Results indicate that both ER and VTG can be used as biomarkers for endocrine disruption in larval fish, and that 4-day exposure to sewage effluent is sufficient to elicit significant expression of these markers in sunshine bass larvae. The extremely higher concentrations of NPEOs found in effluent relative to hormones (approximately 40,000-fold) indicates that surfactant metabolites may be contributing significantly to the estrogenic effects observed. 相似文献