环境内分泌干扰物雌激素的微生物降解研究进展

雌激素是一类重要的环境内分泌干扰物。微生物降解是一种去除环境雌激素与进行环境修复的最绿色、环保、经济的方法。本文从分析雌激素的主要来源和危害、归纳国内外已报道的雌激素降解菌、总结雌激素降解的相关基因和组学研究进展、阐述雌激素的降解通路和降解机制这4个方面,概括阐述了环境雌激素的微生物降解作用,并对未来雌激素降解研究的主要内容与方向提出展望。     

环境雌激素的微生物代谢

环境雌激素作为一类重要的新型环境污染物,可通过干扰生物体的内分泌系统危害生物体健康。微生物降解是去除环境雌激素与进行环境修复的主要手段。本文归纳整理了目前研究较深入的雌激素降解微生物,类比阐述了其预测的降解通路与降解机制,并对后续环境雌激素降解研究的主要内容与方向进行了展望。     

环境雌激素的微生物降解

雌激素作为环境内分泌干扰物的一类重要物质,生物降解法是最为经济、最为绿色和最为适用的去除方法。通过分析雌激素的主要来源和危害、国内外雌激素降解菌的筛选与鉴定、类固醇雌激素降解酶的表达与检测、雌激素降解菌的基因组学特征以及雌激素的降解途径和机制,进一步阐述了雌激素生物降解的研究现状与进展,对未来的研究工作作出了展望。     

二硝基苯胺类除草剂微生物降解研究进展

二硝基苯胺类除草剂是一类广谱、高效且广泛使用的除草剂,微生物的降解代谢作用是其在环境中消解的最主要因素。分离筛选除草剂的高效降解菌株、分析其降解途径并阐明其微生物降解机制,可为除草剂残留污染的微生物降解修复提供理论依据和优良的降解菌株、降解基因和酶资源。本文简述了二硝基苯胺类除草剂的微生物降解菌株、降解代谢途径和降解基因/酶的研究进展,为进一步研究该类除草剂的微生物降解及其污染生物修复提供理论依据和资源。     

微生物降解苯甲酸的研究进展

苯甲酸在工业中的广泛应用使其成为环境中的常见污染物,对微生物好氧降解苯甲酸的邻位途径、间位途径、龙胆酸途径和原儿茶酸途径及厌氧降解途径等进行总结,并对苯甲酸降解过程中发挥重要作用的苯甲酸双加氧酶的种类、不同组分及苯甲酸降解基因和调控基因的基因簇进行介绍,同时展望微生物降解污染物的发展方向。     

环境中污染物降解基因的水平转移(HGT)及其在生物修复中的作用

水平基因转移是不同于垂直基因转移的遗传物质的交流方式.在污染环境这一特异生态环境中,降解基因的水平转移有着独特的功能与作用.研究环境中污染物降解基因在微生物间的水平转移,更深入地了解微生物种群适应污染环境的机理,对于评价污染物的环境毒理、生物可降解性以及污染环境的可修复潜力具有重要参考价值.在污染物生物修复实践中,可以通过调控降解基因的水平转移,增强污染环境中微生物的降解能力,更有效地发挥生物修复作用.文章将对环境中细菌间基因交流的机制,污染物降解基因的水平转移对微生物适应污染环境的机理、水平基因转移对代谢途径的进化及其对污染物生物修复作用的影响等方面的研究进展做一综述.     

除草剂的微生物降解研究进展

微生物降解是环境中农药消解的重要因素,分离筛选纯培养的农药降解微生物并阐述其降解机制为微生物修复环境的应用提供重要的菌株资源和理论依据。本文简述了广泛使用的8类除草剂(包括有机磷类、磺酰脲类、氯乙酰胺类、均三嗪类、芳氧基苯氧基丙酸酯类、苯氧乙酸类、二硝基苯胺类和硫代氨基甲酸酯类除草剂)的降解微生物资源及其降解途径和降解基因的研究进展,并分析了目前除草剂污染修复存在的问题及未来的发展方向。     

多环芳烃微生物降解基因的研究进展

多环芳烃(PAHs)是环境中普遍存在的一类有机污染物,微生物的降解是PAHs去除的主要途径。近年来,有关PAHs微生物降解途径和代谢产物的研究已有很多报道。小分子PAHs一般可以直接被微生物降解,而大分子PAHs则需要微生物以共代谢的方式降解。在过去20年中,微生物降解PAHs的基因相继被发现,各种基因在调控PAHs降解过程中的功能也越来越清晰。本文概述了PAHs微生物降解基因方面的研究进展,详细介绍了微生物对萘、菲的降解基因,最后对PAHs微生物降解基因的应用前景进行了展望。     

微生物降解石油烃的功能基因研究进展

微生物对石油烃的降解在自然衰减去除土壤和地下水石油烃污染的过程中发挥了重要作用。微生物通过其产生的一系列酶来利用和降解这类有机污染物,其中,编码关键降解酶的基因称为功能基因。功能基因可作为生物标志物用于分析环境中石油烃降解基因的多样性。因此,研究石油降解功能基因是分析土著微生物群落多样性、评价自然衰减潜力与构建基因工程菌的重要基础。本文主要介绍了烷烃和芳香烃在有氧和无氧条件下的微生物降解途径,重点总结了烷烃和芳香烃降解的主要功能基因及其作用,包括参与羟化作用的单加氧酶和双加氧酶基因、延胡索酸加成反应的琥珀酸合酶基因以及中心中间产物的降解酶基因等。     

氟喹诺酮类抗生素及耐药基因污染控制的研究进展北大核心CSCD

氟喹诺酮类抗生素属于喹诺酮类抗生素,是一类人畜通用的抗生素。近年来,被广泛应用于人类和畜牧、水产等养殖业领域,然而其大量使用,造成在环境中的不断残留和累积,给自然环境和人类健康造成了较大威胁。现有研究表明,微生物降解是有效去除氟喹诺酮类抗生素残留污染的有效方法之一。本文总结和介绍了近年来氟喹诺酮类抗生素微生物降解单株菌和混合菌群、微生物降解酶、降解途径以及微生物降解氟喹诺酮类抗生素的实际应用,并对目前氟喹诺酮类抗生素微生物降解研究中存在的问题进行了分析,以及对未来氟喹诺酮类抗生素微生物降解研究的重点进行了探讨,以期为后续的研究提供参考。     

Underlying mechanisms mediating the antidepressant effects of estrogens

Background

There is an increased risk for depressive symptoms and affective disorders in individuals who experience drastic drops or fluctuations of gonadal hormones. Moreover, clinical studies indicate that estrogens have the potential to be effective in treating depression.

Scope of the review

Possible underlying mechanisms for the antidepressant activity of estrogens are reviewed and discussed.

Major conclusions

Estrogens exert their antidepressant activity via a multimodal mechanism of action by regulating several pathways and functions associated with antidepressive effects. Estrogens increase serotonergic activity by regulating the synthesis and degradation of serotonin, as well as spontaneous firing of the serotonergic neurons in the raphe nuclei. Both pre- and postsynaptic serotonin receptors are shown to be regulated by estrogens. In addition, estrogens are neurotrophic and promote neuroplasticity and neurogenesis. Similar effects are also observed after treatment with current antidepressant therapies. However in stark contrast to current therapies which must be administered chronically to produce an effect, the responses to estrogens are often observed after a single dose. Many of these estrogenic effects, including antidepressant and anxiolytic responses in behavioral models in rodents, appear to be mediated via the estrogen receptor β subtype.

General significance

The rapid onset of action combined with the multifactorial mechanism of action of estrogens indicates that estrogen treatment could complement currently available therapies for depression. Considering safety aspects, selective estrogen receptor β agonists would probably be the optimal estrogenic therapy.     

Oestrogènes et reproduction masculine

The role of estrogen on male reproductive function has become clearer in the last decade. During these years the study of the effect of testosterone, estrogen or an aromatase inhibitor in hypogonadal men provided a first evidence of the effects of estrogens in the regulation of gonadotropin secretion. At the same time, the development of a line of transgenic male mice lacking estrogen receptor α, estrogen receptor β or aromatase gene provided further evidence about the role of estrogens not only in the regulation of gonadotropin secretion, but also on the effects of estrogens on testicular function and development. A confirmation of these actions of estrogens came from the observation of naturally occurring mutations of the estrogen receptor and of the aromatase gene in human males. Based on these data it has been demonstrated that estrogens are major regulators of gonadotropin secretion acting both at pituitary and hypotalamic level. The presence in the human reproductive structures of estrogen receptor α, estrogen receptor β and the aromatase enzyme indicates the existence of receptor α, estrogen receptor β or aromatase estrogen actions at this level. Anyway, the precise role of estrogens in testicular development and function and on the regulation of human spermatogenesis has not yet been precisely clarified.     

Estrogens and male reproduction

The role of estrogen on male reproductive function has become clearer in the last decade. During these years the study of the effect of testosterone, estrogen or an aromatase inhibitor in hypogonadal men provided a first evidence of the effects of estrogens in the regulation of gonadotropin secretion. At the same time, the development of a line of transgenic male mice lacking estrogen receptor α, estrogen receptor β or aromatase gene provided further evidence about the role of estrogens not only in the regulation of gonadotropin secretion, but also on the effects of estrogens on testicular function and development. A confirmation of these actions of estrogens came from the observation of naturally occurring mutations of the estrogen receptor and of the aromatase gene in human males. Based on these data it has been demonstrated that estrogens are major regulators of gonadotropin secretion acting both at pituitary and hypotalamic level. The presence in the human reproductive structures of estrogen receptor α, estrogen receptor β and the aromatase enzyme indicates the existence of receptor α, estrogen receptor β or aromatase estrogen actions at this level. Anyway, the precise role of estrogens in testicular development and function and on the regulation of human spermatogenesis has not yet been precisely clarified.     

Selective inhibition of protein disulfide isomerase by estrogens

Protein disulfide isomerase (PDI) is a multifunctional microsomal enzyme that participates in the formation of protein disulfide bonds. PDI catalyzes the reduction of protein disulfide bonds in the presence of excess reduced glutathione and has been implicated in the reductive degradation of insulin; E. coli thioredoxin is homologous to two regions in PDI and can also degrade insulin. PDI activity, measured by 125I-insulin degradation or reactivation of randomly oxidized RNase in the presence of reduced glutathione, is non-competitively inhibited by estrogens; half-maximal inhibition was observed at approximately 100 nM estrogen. Other steroid hormones at 1 microM had little or no effect. PDI segment 120-163 (which corresponds to exon 3 of the PDI gene) and 182-230 have significant similarity with estrogen receptor segments 350-392 and 304-349, respectively, located in the estrogen binding domain but not with the steroid domains of the progesterone and glucocorticoid receptors or with thioredoxin, which is insensitive to estrogens. We propose the hypothesis that enzymes can acquire sensitivity to a hormone via exon shuffling to the enzyme gene from the DNA region coding for the hormone binding domain of the hormone's receptor.     

The preparation of pregnancy urine for an estrogen profile.

A method is described for purifying the estrogen content of pregnancy urine with little loss of the labile estrogens. The procedure makes use of the initial 50-fold purification effected by their precipitation whith ammonium sulphate, with simultaneous elimination of most urinary corticosteroids and 50--60% of urinary ketosteroids. It also employs the antioxident ascorbic acid as an additive in most stages of the procedure. The mild organic-solvent-HIO partition system of Brown is used for separating the strongly polar, 2including all "labile" estrogens, and of the weakly polar estrogens, from neutral steroids. The remaining neutral steroid still interfering with the assays were removed by an ascorbic acid treated ion exchange resin (AG 1). The final residues were revealed by mass-spectroscopy to consist almost solely of estrogens. Gas-liquid chromatography in which just 2 chromatograms are required yields a total of 12 "estrogen" peaks (for 12 estrogens which are excreted in amounts greater than 0.1 mg/day) in normal pregnancy urine, including all the known labile estrogens. Identification as estrogen for all but a few minor peaks of the gas chromatogram was obtained by mass-spectroscopy. The practical significance of the method lies in the fact that some labile estrogens are much more important in the estrogen metabolism of pregnant and nonpregnant women than heretofore generally thought.