环境激素类物质对人类健康的影响

环境激素是具有生物体内分泌激素干扰作用的一大类化学物质。环境激素在环境中普遍存在,不仅对生物的繁殖具有一定影响,而且还对生物的许多行为和感知能力产生影响。论文综述了近年来国内外有关环境激素的研究进展,综合分析了环境激素对人类健康的影响,阐述了其作用机理,并探讨了环境激素类物质控制和管理途径。     

环境激素对人类健康的危害及其作用机制

环境激素是环境中的激素类似物,它在人体和动物体内发挥着类似于激素的作用,通常称为＂外因性内分泌干扰物质＂,干扰体内正常激素的作用.该文介绍激素与环境激素的区别、环境激素的特性、种类;重点阐述环境激素的及其内分泌干扰机制;从环境激素对人类的健康,尤其是对生殖健康的危害,提出了防治环境激素污染的措施.     

双酚A的内分泌干扰效应研究进展

双酚A(Bisphenol A, BPA)是一种危害生物体内分泌干扰效应的环境激素。近年来, 随着工农业的不断发展, 造纸行业、电子产品、食品包装等行业大量使用BPA, 国内外主要河流、湖泊都不同程度受到了BPA的污染。BPA通过富集会影响人类激素的合成、释放、转运, 进而影响人的生殖和发育。BPA的毒性效应主要包括内分泌干扰物、神经毒素、免疫毒素等方面, 这些致毒效应甚至会增加细胞癌变、畸变的可能性。此外BPA毒性替代物、BPA与其他物质结合的产物都增加了BPA毒性的多样性, 逐渐成为了危害人类生命安全的又一大隐患。通过研究BPA毒性效应以及近年来BPA的替代品, 了解双酚A的致毒机理, 为研究预防控制BPA污染对人类健康的影响提供参考依据。     

葡萄环境激素污染的研究进展

环境激素类污染物是农产品质量安全的重要风险因子之一。为了解我国葡萄中的环境激素污染现状,文章综述了葡萄中邻苯二甲酸酯、农药、植物生长调节剂和重金属类污染物的研究进展,结果表明：我国葡萄中的环境激素污染目前处于低风险状态,建议开展环境激素污染在农作物中的迁移、积累、转化机理研究、完善植物生长调节剂残留限量值以及开展多种环境激素共存下的联合风险研究。     

邻苯二甲酸二乙酯和壬基酚联合暴露对杜氏盐藻生长的影响

为了探讨环境激素类物质邻苯二甲酸二乙酯(DEP)和壬基酚(NP)对海洋微藻的联合毒性效应,选取杜氏盐藻(Dunaliella salina)为受试生物,以环境激素对杜氏盐藻单一暴露的96h EC₅₀的毒性效应作为一个毒性单位(IU),采用毒性单位法比较研究了DEP和NP单一暴露以及两者以三种不同混合比例(毒性单位比:1:1、1:4和4:1)暴露对杜氏盐藻的细胞生长、叶绿体色素含量、可溶性蛋白含量、SOD活性以及最大光能转化效率(Fv/Fm)的影响.实验结果表明:DEP和NP单一暴露对杜氏盐藻的96h EC₅₀分别为69.54 mg/L和1.47 mg/L,两种环境激素对杜氏盐藻均有抑制作用,且NP较DEP对杜氏盐藻的毒性更强.DEP和NP联合暴露较单一暴露对杜氏盐藻的细胞生长、叶绿体色素和可溶性蛋白的合成有较强的抑制作用,两种环境激素在毒性单位比为1:1、1:4、4:1三个比例水平上的联合毒性效应均表现为协同效应,其中比例为1:1的协同效应最强.     

环境雌激素生态影响的研究进展

环境雌激素(ｅｃｏｅｓｔｒｏｇｅｎ) ,是指能够扰乱动物内分泌活动 ,生理活性与雌激素较为相似的动物体外化学物质 ,包括人工合成化合物以及植物天然雌激素 ,由于目前所发现的干扰动物及人体内分泌系统的有机化合物绝大多数都具有激素特征 ,因此通常又将环境激素称做“干扰内分泌化合物”(ｅｎｄｏｃｒｉｎｅｄｉｓｒｕｐｔｉｎｇｃｈｅｍｉ ｃａｌｓ或ｅｎｄｏｃｒｉｎｅｄｉｓｒｕｐｔｅｒｓ)。环境激素问题只是在最近几年才引起世界关注 ,但由于环境激素污染范围广、影响大 ,对人类生存的威胁更直接 ,目前 ,西方国家将环境激素问题与臭…     

邻苯二甲酸酯联合暴露对杜氏盐藻生长的影响

联合毒性效应是指两种或两种以上的化学物质同时或短时期内先后作用于机体所产生的综合毒性作用.论文探讨了典型环境激素邻苯二甲酸二甲酯(DMP)与邻苯二甲酸二乙酯(DEP)对杜氏盐藻(Dunaliella salina )的联合毒性效应.实验以96h的单一毒性效应EC₅₀为一个毒性单位(TU),将上述两种环境激素按照毒性单位比1:1、1:4和4:1的三种比例水平两两组合进行联合毒性试验,研究不同处理下,两种典型环境激素对杜氏盐藻生长的影响.结果表明:两种环境激素对杜氏盐藻生长均有抑制作用,且联合暴露较单一暴露对杜氏盐藻的细胞生长和光合作用抑制更强;DMP和DEP单一暴露对杜氏盐藻的96h EC₅₀分别为317.49mg·L^-1、和69.54mg·L^-1.两者在1:1、1:4和4:1三个比例水平上的联合毒性效应均表现为相加或协同效应,其中比例为1:1的协同效应最强.     

环境激素—危险的环境污染物

激素是由人或动物内分泌腺或散在的内分泌细胞所分泌的高效能生物活性物质 ,它与神经系统密切联系 ,共同调节机体的多种功能活动 ,维持人体内环境的相对稳定。近几年来人们发现在环境中存在一些化学物质 ,它们具有类似人体激素的功能 ,有时能引起机体内分泌紊乱 ,故将其称为“环境激素”。1　环境激素的来源和作用方式环境激素是社会生产工业化的产物。特别是近 70年来 ,随着大量的化学合成物的生产、使用 ,一些具有激素功能的化合物也随之排入周围环境产生污染 ,造成巨大的危害。目前全球已合成的化学物质有 10 0 0万种 ,每年还新合成 10万…     

浅谈环境激素

环境激素是指由于人类的生产和生活活动而释放到环境中的、对人体内和动物体内的正常激素功能施加影响,从而影响内分泌系统的化学物质;本文介绍了环境激素的种类、危害及防控方法。     

激素对无尾两栖动物声学通讯影响的研究进展

声学通讯是动物对内外环境刺激的一种反应,对无尾两栖动物的配偶选择和成功繁殖起着关键作用。从声学通讯的类型和声谱特征等入手,综述了影响两栖动物声学通讯的3个主要因素:发声器、体内激素及体外激素水平。在此基础上,分析了激素调控无尾两栖动物声学通讯的作用机理,对无尾两栖动物声学通讯今后的研究方向进行了展望,并探讨了环境激素对其影响,以期为无尾两栖动物生殖生态环境的保护和恢复提供理论支撑。     

Environmental oestrogens disrupt testicular descent and damage male reproductive health: Mechanistic insight

Environmental oestrogens (EEs) as environmental pollutants have been paid much attention due to their impact on congenital malformation of male genitourinary system. Exposure to EEs for prolonged time could hinder testicular descent and cause testicular dysgenesis syndrome. Therefore, it is urgent to understand the mechanisms by which EEs exposure disrupt testicular descent. In this review, we summarize recent advances in our understanding of the process of testicular descent, which is regulated by intricate cellular and molecular networks. Increasing numbers of the components of these networks such as CSL and INSL3 are being identified, highlighting that testicular descent is a highly orchestrated process that is essential to human reproduction and survival. The exposure to EEs would lead to the imbalanced regulation of the networks and cause testicular dysgenesis syndrome such as cryptorchidism, hypospadias, hypogonadism, poor semen quality and testicular cancer. Fortunately, the identification of the components of these networks provides us the opportunity to prevent and treat EEs induced male reproductive dysfunction. The pathways that play an important role in the regulation of testicular descent are promising targets for the treatment of testicular dysgenesis syndrome.     

Endocytic and Secretory Traffic in Arabidopsis Merge in the Trans-Golgi Network/Early Endosome,an Independent and Highly Dynamic Organelle

Plants constantly adjust their repertoire of plasma membrane proteins that mediates transduction of environmental and developmental signals as well as transport of ions, nutrients, and hormones. The importance of regulated secretory and endocytic trafficking is becoming increasingly clear; however, our knowledge of the compartments and molecular machinery involved is still fragmentary. We used immunogold electron microscopy and confocal laser scanning microscopy to trace the route of cargo molecules, including the BRASSINOSTEROID INSENSITIVE1 receptor and the REQUIRES HIGH BORON1 boron exporter, throughout the plant endomembrane system. Our results provide evidence that both endocytic and secretory cargo pass through the trans-Golgi network/early endosome (TGN/EE) and demonstrate that cargo in late endosomes/multivesicular bodies is destined for vacuolar degradation. Moreover, using spinning disc microscopy, we show that TGN/EEs move independently and are only transiently associated with an individual Golgi stack.     

PxdA interacts with the DipA phosphatase to regulate peroxisome hitchhiking on early endosomes

In canonical microtubule-based transport, adaptor proteins link cargoes to dynein and kinesin motors. Recently, an alternative mode of transport known as “hitchhiking” was discovered, where cargoes achieve motility by hitching a ride on already-motile cargoes, rather than attaching to a motor protein. Hitchhiking has been best studied in two filamentous fungi, Aspergillus nidulans and Ustilago maydis. In U. maydis, ribonucleoprotein complexes, peroxisomes, lipid droplets (LDs), and endoplasmic reticulum hitchhike on early endosomes (EEs). In A. nidulans, peroxisomes hitchhike using a putative molecular linker, peroxisome distribution mutant A (PxdA), which associates with EEs. However, whether other organelles use PxdA to hitchhike on EEs is unclear, as are the molecular mechanisms that regulate hitchhiking. Here we find that the proper distribution of LDs, mitochondria, and preautophagosomes do not require PxdA, suggesting that PxdA is a peroxisome-specific molecular linker. We identify two new pxdA alleles, including a point mutation (R2044P) that disrupts PxdA’s ability to associate with EEs and reduces peroxisome movement. We also identify a novel regulator of peroxisome hitchhiking, the phosphatase DipA. DipA colocalizes with EEs and its association with EEs relies on PxdA. Together, our data suggest that PxdA and the DipA phosphatase are specific regulators of peroxisome hitchhiking on EEs.     

Differential effects of natural and environmental estrogens on endothelin synthesis in bovine oviduct cells

Endothelin-1 (ET-1), a vasoconstrictor and mitogenic peptide that plays an important role within the endocrine/reproductive system, is synthesized by oviduct cells and regulates tubal contractility. Because 17beta-estradiol (estradiol) regulates oviduct function by influencing the synthesis of autocrine/paracrine factors, estradiol may also regulate ET-1 synthesis. Furthermore, environmental estrogens (EEs; phytoestrogens and xenoestrogens), which structurally resemble estradiol and possess estrogenic activity, may mimic the effects of estradiol on ET-1 synthesis and may influence the reproductive system. Using cultures of bovine oviduct cells (epithelial cells:fibroblasts, 1:1), we investigated and compared the modulatory effects of estradiol, phytoestrogens, and xenoestrogens on ET-1 synthesis and determined whether these effects were estrogen receptor (ER) mediated. A quantitative ELISA for ET-1 in the culture medium revealed that 17beta-estradiol inhibits ET-1 synthesis in a concentration-dependent manner (4-400 nmol/L). In contrast to estradiol, ET-1 synthesis was induced in cell cultures treated with xenoestrogens in the following order of potency (0.1 micromol/L): 4-hydroxy-trichlorobiphenyl > 4-hydroxy-dichlorobiphenyl > trichlorobiphenyl. The stimulatory effects of xenoestrogens on ET-1 production were mimicked by the phytoestrogens biochanin-A and genistein but not by formononetin, equol, and daidzein. The oviduct cells expressed both ERs (alpha and beta), but the modulatory effects of estradiol, but not EEs, on ET-1 synthesis were blocked by ICI-182 780 (1 microM), a pure ER antagonist. Our results provide evidence that estradiol inhibits ET-1 synthesis in oviduct cells via an ER-dependent mechanism, whereas, EEs induce ET-1 synthesis via an ER-independent mechanism. The contrasting effects of EEs on ET-1 synthesis suggests that EEs may act as endocrine modulators/disruptors and may have deleterious effects on the reproductive system by adversely influencing the biology and physiology of the oviduct.     

Mathematical modelling and experiments for the proliferation and differentiation of Drosophila intestinal stem cells II

The Drosophila posterior midgut epithelium mainly consists of intestinal stem cells (ISCs); semi-differentiated cells, i.e. enteroblasts (EBs); and two types of fully differentiated cells, i.e. enteroendocrine cells (EEs) and enterocytes (ECs), which are controlled by signalling pathways. In [M. Kuwamura, K. Maeda, and T. Adachi-Yamada, Mathematical modeling and experiments for the proliferation and differentiation of Drosophila intestinal stem cells I, J. Biol. Dyn. 4 (2009), pp. 248-257], on the basis of the functions of the Wnt and Notch signalling pathways, we studied the regulatory mechanism for the proliferation and differentiation of ISCs under the assumption that the Wnt proteins are supplied from outside the cellular system of ISCs. In this paper, we experimentally show that the Wnt proteins are specifically expressed in ISCs, EBs, and EEs, and theoretically show that the cellular system of ISCs can be self-maintained under the assumption that the Wnt proteins are produced in the cellular system of ISCs. These results provide a useful basis for determining whether an environmental niche is required for maintaining the cellular system of tissue stem cells.     

Diethylstilbestrol regulates mouse gubernaculum testis cell proliferation via PLC‐Ca2+‐CREB pathway

Recent evidence suggested a positive correlation between environmental estrogens (EEs) and high incidence of abnormalities in male urogenital system, but the mechanism remains unclear. Diethylstilbestrol (DES) is a nonsteroidal synthetic estrogen that disrupts the morphology and proliferation of gubernaculum testis cells, but the underlying mechanism is unclear. In this study, mouse gubernaculum testis cells were pretreated with phospholipase C (PLC) inhibitor U‐73122 and then treated with DES. The results demonstrated that U‐73122 impaired DES‐evoked intracellular Ca2+ mobilization in gubernaculum testis cells and inhibited DES‐induced proliferation of gubernaculum testis cells. Mechanistically, we found that U‐73122 inhibited DES‐induced activation of cAMP‐response element binding protein (CREB) in gubernaculum testis cells. In conclusion, these data suggest that the effects of DES on mouse gubernaculum testis cells are mediated by PLC‐Ca²⁺‐CREB pathway.

Significance of the study

Environmental estrogens remain a serious threat to male reproductive health, and it is important to understand the mechanism by which EEs affect the male productive system. Here we explore potential mechanisms how the proliferation and contractility of gubernaculum testis cells are regulated by diethylstilbestrol. Our findings provide the first evidence that PLC‐Ca²⁺‐CREB signalling pathway mediates the nongenomic effects of diethylstilbestrol on gubernaculum testis cells. These findings provide new insight into the role of diethylstilbestrol in the aetiology of male reproductive dysfunction and will help develop better approaches for the prevention and therapy of male reproductive malformation.     

Mathematical modelling and experiments for the proliferation and differentiation of Drosophila intestinal stem cells II

The Drosophila posterior midgut epithelium mainly consists of intestinal stem cells (ISCs); semi-differentiated cells, i.e. enteroblasts (EBs); and two types of fully differentiated cells, i.e. enteroendocrine cells (EEs) and enterocytes (ECs), which are controlled by signalling pathways. In [M. Kuwamura, K. Maeda, and T. Adachi-Yamada, Mathematical modeling and experiments for the proliferation and differentiation of Drosophila intestinal stem cells I, J. Biol. Dyn. 4 (2009), pp. 248–257], on the basis of the functions of the Wnt and Notch signalling pathways, we studied the regulatory mechanism for the proliferation and differentiation of ISCs under the assumption that the Wnt proteins are supplied from outside the cellular system of ISCs. In this paper, we experimentally show that the Wnt proteins are specifically expressed in ISCs, EBs, and EEs, and theoretically show that the cellular system of ISCs can be self-maintained under the assumption that the Wnt proteins are produced in the cellular system of ISCs. These results provide a useful basis for determining whether an environmental niche is required for maintaining the cellular system of tissue stem cells.     

Isolation of extrachromosomal elements by histone immunoprecipitation

Here, we describe a gentle and effective method for the rapid and reproducible isolation of histone-bound extrachromosomal DNA molecules called extrachromosomal elements (EEs). This method facilitates the harvest of a specific population of EEs following their isolation from cultured cells, primary tissues, and tumor cells. Active EEs are bound to histone proteins, and these histone-bound EEs carry actively transcribing genes such as c-myc. Our method exploits the presence of histones on EEs and serves as a first-step purification procedure, allowing for the cloning or multivariant analysis of an immunopurified sample of EEs. We isolated EEs from 4-hydroxytamoxifen (4-HT)-activated Myc-ER-regulatable Pre-B ABM cells. Following one round of immunoprecipitation, we demonstrate the purification of histone-bound EEs. We confirmed that our purification enriched for EEs that carry genes by fluorescent in situ hybridization of EEs (FISH-EEs), and we probed non-enriched and immunopurified EEs with a dihydrofolate reductase (DHFR) cDNA probe that is known to detect extrachromosomal amplification in Myc-activated cells. We demonstrate the enrichment of immunoprecipitated DHFR-containing extrachromosomal DNA molecules.     

Effect of the background activity of a network of excitatory neuron-like elements on the conduction of excitation

Calculation on a mathematical model showed that for distortion-free conduction of excitation through a net of excitatory elements (EEs) a system is necessary of optimum correlation of EEs parameters, links between them and of external influences. When these parameters are deviated from their optimum values, excitation is conducted through the net either with attenuation or with intensification (as a result of divergence and convergence of the influences of the previous layer on the following one). The background activity which is above threshold of impulse activity emergence and which is created by common effects on all EEs, prevents the revealing of the input EEs activation at the net output. Near-threshold tonic net activation facilitates excitation conduction through it. Periodic net activity facilitates excitation conduction through it only under optimum correlation of its parameters and the time of its conduction through the net. At disturbance of this condition, excitation conduction through the net is limited.     

Responses to environmental stresses in woody plants: key to survive and longevity

Environmental stresses have adverse effects on plant growth and productivity, and are predicted to become more severe and widespread in decades to come. Especially, prolonged and repeated severe stresses affecting growth and development would bring down long-lasting effects in woody plants as a result of its long-term growth period. To counteract these effects, trees have evolved specific mechanisms for acclimation and tolerance to environmental stresses. Plant growth and development are regulated by the integration of many environmental and endogenous signals including plant hormones. Acclimation of land plants to environmental stresses is controlled by molecular cascades, also involving cross-talk with other stresses and plant hormone signaling mechanisms. This review focuses on recent studies on molecular mechanisms of abiotic stress responses in woody plants, functions of plant hormones in wood formation, and the interconnection of cell wall biosynthesis and the mechanisms shown above. Understanding of these mechanisms in depth should shed light on the factors for improvement of woody plants to overcome severe environmental stress conditions.