Eco-physiological responses of Polytrichum commune to soil contamination by polychlorinated biphenyls

 通过微体繁殖技术在多氯联苯(PCBs)污染土壤基质上进行大金发藓(Polytrichum commune)的室内培养, 研究了不同浓度(5、10和20 mg·kg^–1)低氯PCBs (Aroclor 1242)和高氯PCBs (Aroclor 1254)对大金发藓生理生态指标的影响。经6个月的培养, 大金发藓的密度和盖度分别达93%和50株·cm^–2以上, PCBs处理组与对照组相比无显著差异, 表明PCBs对大金发藓茎叶碎片再生成新植株体的能力没有产生不利影响。大金发藓鲜质量和株高随低氯PCBs (Aroclor 1242)浓度增加而增加、随高氯PCBs (Aroclor 1254)浓度增加而减小, 但均高于对照, 表明PCBs处理对大金发藓的生长具有一定的促进作用。PCBs处理组大金发藓叶绿素a、b以及叶绿素a + b含量较对照组有所增加, 叶绿素a/b值与对照组相比基本没有变化。PCBs处理组大金发藓膜脂过氧化产物丙二醛含量和超氧化物歧化酶活性与对照组相比无显著差异, 谷胱甘肽含量较对照组显著增加, 表明谷胱甘肽在大金发藓体内活性氧清除过程中起重要作用。总体来看, 大金发藓能在所设浓度的PCBs范围内正常生长, 对PCBs有较强的耐性。     

The effect of polychlorinated biphenyls (PCBs) on the membrane lipids of Pseudomonas stutzeri

In this study we examined the effect of polychlorinated biphenyls (PCBs) on biomass production of a PCB-degrading Pseudomonas stutzeri, and on the fatty acid profile of its major membrane lipids. Growth based on biomass weight was stimulated when PCBs were added at the time of inoculation, but PCB addition three days after inoculation led to a significant decrease in biomass. Simultaneous addition of PCBs plus biphenyl or PCBs plus carvone negatively affected P. stutzeri biomass (addition of biphenyl or carvone at the time of inoculation and PCBs to three-day-old culture). In the presence of PCBs alone the amount of the prevalent fatty acids C16:0 and C17-cyclopropyl fatty acid (C17-CP) of P. stutzeri in total and neutral lipids was significantly reduced. When PCBs were added together with carvone (carvone at the time of inoculation and PCBs after three days) a significant reduction of these fatty acids was obtained, but, in addition, oleic, cis-vaccenic, and cyclononadecanic (C19-CP) acids were increased. When PCBs were combined to biphenyl the prevalent fatty acids were reduced and oleic, cis-vaccenic, and cyclononadecanic acids were increased in total and neutral lipids. Addition of 3-chlorobenzoic acid led to a significant growth inhibition and to the production of oleic and cis-vaccenic acids in the membrane fraction phosphatidylcholine.     

The influence of polychlorinated biphenyls (PCBs) and phytoestrogens in vitro on functioning of reproductive tract in cow

Ovarian, endometrial and myometrial cells and strips of longitudinal myometrium from cows on defined days of estrous cycle were treated for 24-72 h with different doses (1-100 ng/ml) of PCBs mixture (Aroclor 1248) or with one of PCB congeners (126, 77, 153). The administered doses of PCBs neither affected the viability of cells nor influenced the ovarian steroidogenesis as measured by progesterone (P(4)), estradiol (E(2)) and testosterone secretion from luteal, granulosa and theca cells, respectively. In contrast, PCBs clearly inhibited a FSH and LH-stimulated effect on steroids secretion from granulosa and luteal cells. Moreover, PCBs significantly stimulated oxytocin (OT) secretion from the studied ovarian cells, and at least part of this effect is elicited through activation of glucocorticoid receptors. Further, PCBs were found to increase basal intracellular concentrations of Ca(2+) and both spontaneous and OT-stimulated contractions of myometrial strips. Concomitantly, PCBs increased endometrial secretion of PGF(2alpha), hence the ratio of PGF(2alpha):PGE(2) was also increased. Phytoestrogens (genistein, daidzein, coumestrol), with a different intensity, reduced the effect of PCBs on PGF(2alpha) secretion and myometrial contractions. Genistein inhibited PCBs' effect on OT secretion from granulosa cells, while PCB's effect on OT release from luteal cells was reduced mainly by genistein and daidzein. We conclude that PCBs can impair both ovarian functioning and uterine contractility, while phytoestrogens are able to reduce this effect.     

Alteration of serotonin system by polychlorinated biphenyls exposure

Although commercial production of polychlorinated biphenyls (PCBs) was banned in 1979, PCBs continue to be an environmental and health concern due to their high bioaccumulation and slow degradation rates. In fact, PCBs are still present in our food supply (fish, meat, and dairy products). In laboratory animals, exposure to single PCB congener or to mixtures of different congeners induces a variety of physiological alterations. PCBs cross the placenta and even exposure at low level is harmful for the foetus by leading to neurodevelopment alterations. Serotonin system which regulates many physiological functions from platelet activation to high cerebral processes and neurodevelopment is one of the targets of PCBs toxicity. The effects of PCBs exposure on serotonin system have been investigated although to a lesser extent compared to its effect in other neurotransmitter systems. This review provides a summary of the results concerning the impact of PCBs exposure (in vitro and in vivo) on serotonin system. Further research is needed to correlate specific deficits with PCB-induced changes in the serotonin system.     

Degradation of polychlorinated biphenyls by hairy root culture of Solanum nigrum

Polychlorinated biphenyls (PCBs) present in the commercial mixture Delor 103 were transformed by hairy root culture of Solanum nigrum. Plant growth regulators kinetin, 2,4-dichlorophenoxy-acetic acid, benzylaminopurin and/or naph-thaleneacetic acid, influenced the cells' growth and transformation of PCBs in a different manner. The cells were able to transform PCBs even if they ceased growing. Young inoculum (16 days) had a 20% lower PCB conversionthan did older inocula (37, 68 days) while biomass increase was much higher using young inoculum. With increasing size of inoculum, transformation of PCBs was stimulated. After 30 days of incubation the average amount of residual PCBs was 40% of the controls at initial PCB concentration of 100 ppm.     

Toxicity Reference Values for the Toxic Effects of Polychlorinated Biphenyls to Aquatic Mammals

Threshold tissue residue concentrations of polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) were derived from the published results of semi-field (i.e., field collected food items were used as a medium of exposure to PCBs in laboratory reared animals) or field toxicity studies conducted with seals, European otters and mink. Based on biomagnification factors (BMFs) and concentrations of PCBs or TEQs measured in fish fed in the diet of experimental aquatic mammals, dietary threshold concentrations were estimated. Hepatic vitamin A, thyroid hormone concentration, suppression of natural killer (NK) cell activity and proliferative response of lymphocytes to mitogens were the toxicity endpoints measured in aquatic mammals. Threshold concentrations for PCBs or TEQs in livers of aquatic mammals to elicit the physiological effects ranged from 6.6 to 11?µg PCBs/g (geometric mean: 8.7?µ/g) and 160 to 1400?pg TEQs/g (geometric mean: 520?pg/g), lipid weight, respectively. The BMFs for PCBs and TEQs varied depending on the marine mammal species, and therefore the dietary threshold concentrations could be referred only by a range of values (rather than a mean value), which were 10 to 150?ng PCBs/g and 1.4 to 1.9?pg TEQs/g, wet weight, for PCBs and TEQs, respectively.     

Remediation of PCBs in soil by surfactant washing and biodegradation in the wash by Pseudomonas sp. LB400

Solutions from the washing of polychlorinated biphenyl (PCB)-contaminated soil with a variety of commercial nonionic or anionic surfactants were incubated with Pseudomonas sp. LB400 in an attempt to remediate the soil and destroy the PCBs. Nonionic surfactants washed more PCBs from the soil (up to 89%) but inhibited their biodegradation. Anionic surfactants washed less PCBs from the soil but were more effective in biodegradation tests, removing up to 67% of total PCBs.     

In vitro effects of polychlorinated biphenyls (PCBs) on the contractility of bovine myometrium from the periovulatory stage of the estrous cycle

Strips of longitudinal myometrium from cows were obtained on days 19-21 and 1-5 of the estrous cycle and incubated (aerated atmosphere; 4 degrees C; 24, 48 or 72 h) with a mixture of PCBs Aroclor (Ar) 1248 or with one of three PCBs (77, 126 or 153), all at doses of 10 or 100 ng/ml. The force and frequency of spontaneous and oxytocin (OT; 10(-7)M)-stimulated contractions of each strip was registered by means of HSE Schuler Organbath. Contractions of myometrial strips in the presence and absence of PCBs were observed after 24, 48 and 72 h of incubation. All PCBs significantly affected myometrial contractions. A mixture of PCBs increased the spontaneous force of contractions after 24 h but decreased after 48 h. Individual congeners of PCB also amplified the force of contractions and in most cases this effect was dose-dependent. Response of myometrium to PCB-126 and PCB-153 or PCB-77 appeared after 24 h or 48 h of incubation. Incubation of myometrial strips with PCB congeners markedly amplified OT-stimulated contractions. This effect was less evident when tissue was pre-treated with a higher dose of PCBs. Pre-treatment with estrogen-like PCB-153 increased the spontaneous and OT-evoked frequency of myometrial contractions from days 19-21. The spontaneous force of myometrial strips' contractions as well as the effects evoked by PCBs and OT was higher before than after ovulation. In summary, PCBs affected both the force and frequency of uterine contractions. Thus, it can be concluded that PCBs may impair both ovum fertilization and blastocyst implantation in cows.     

Stir bar sorptive extraction–thermal desorption–capillary gas chromatography–mass spectrometry applied to the analysis of polychlorinated biphenyls in human sperm

Stir bar sorptive extraction (SBSE) on polydimethylsiloxane (PDMS) was applied to the enrichment of polychlorinated biphenyls (PCBs) from human sperm. The seven Ballschmiter PCBs were used as model compounds. The extracted PCBs were then thermally desorbed from the stir bar and analysed on-line by capillary gas chromatography (CGC) with mass spectrometric detection (MS). Method development started with the analysis of PCBs spiked in water. Methanol had to be added to the samples in order to reduce the influence of glass adsorption on recovery and reproducibility. Recoveries in water for all PCBs varied around 50–60% and were limited for low molecular mass (MM) PCBs by polarity changes in the sample due to methanol addition and for high MM PCBs by non-equilibrium conditions. Matrix suppression by the lipophilic medium lowered the recoveries in the sperm samples proportional with PCB polarity. The method was validated and although limits of detection (LOD) for the individual congeners were in the sub-ppt level (<pg/ml), the limit of quantification (LOQ) was set at 10 ppt (10 pg/ml).     

Microorganisms Degrading Polychlorinated Biphenyls

Four strains belonging to the genus Bacilluscapable of degrading polychlorinated biphenyls (PCBs) were isolated by screening collection strains of soil bacteria degrading an organochlorine pesticide, hexachlorocyclohexane (HCCH). A method for production of tritium-labeled PCBs was developed. Consumption and degradation of PCBs by the soil bacterial strains selected were studied using tritium-labeled PCBs and GLC. It was demonstrated that PCBs are degradable both in culture media and in model soil samples.     

An Integrated Surfactant Solubilization and PCB Bioremediation Process for Soils

Two decades after the manufacture and use of polychlorinated biphenyls (PCBs) were banned, PCB contamination remains widespread in the environment. Technologies available for PCB remediation are limited and often impractical for soils with dispersed PCB contamination. In this study, two remediation processes have been integrated for use on PCB-contaminated soils. This remediation strategy links in situ surfactant washing of PCBs from soil with aerobic biodegradation of the resulting surfactant-PCB solution by two field application vectors (F A Vs), Pseudomonas putida IFL5::TnPCB and Ralstonia eutropha B30F4::TnPCB, which utilize surfac-tants as growth substrates and cometabolize PCBs. A bench-scale demonstration of this process was performed using PCB-contaminated soils from an electric power substation site. In a 2-day recycling wash using a 1% (wt/vol) surfactant solution, greater than 70% of the PCBs were removed from the soil. In the biodegradation phase, greater than 90% of the surfactant and 35% of the PCBs were biodegraded in 12 days. The residual PCBs were partitioned onto a solid carrier resulting in greater than 90% removal of PCBs from the bioreactor effluent and a 50-fold reduction in the amount of PCB-contaminated material.     

Polychlorinated Biphenyls (PCBs) Enhance Metastatic Properties of Breast Cancer Cells by Activating Rho-Associated Kinase (ROCK)

Background

Polychlorinated biphenyls (PCBs) are a family of structurally related chlorinated aromatic hydrocarbons. Numerous studies have documented a wide spectrum of biological effects of PCBs on human health, such as immunotoxicity, neurotoxocity, estrogenic or antiestrogenic activity, and carcinogensis. The role of PCBs as etiologic agents for breast cancer has been intensively explored in a variety of in vivo, animal and epidemiologic studies. A number of investigations indicated that higher levels of PCBs in mammary tissues or sera correlated to breast cancer risk, and PCBs might be implicated in advancing breast cancer progression.

Methodology/Principal Findings

In the current study, we for the first time report that PCBs greatly promote the ROCK activity and therefore increase cell motility for both non-metastatic and metastatic human breast cancer cells in vitro. In the in vivo study, PCBs significantly advance disease progression, leading to enhanced capability of metastatic breast cancer cells to metastasize to bone, lung and liver. Additionally, PCBs robustly induce the production of intracellular reactive oxygen species (ROS) in breast cancer cells; ROS mechanistically elevate ROCK activity.

Conclusions/Significance

PCBs enhance the metastatic propensity of breast cancer cells by activating the ROCK signaling, which is dependent on ROS induced by PCBs. Inhibition of ROCK may stand for a unique way to restrain metastases in breast cancer upon PCB exposure.     

Flow cytometry analysis of changes in the DNA content of the polychlorinated biphenyl degrader Comamonas testosteroni TK102: effect of metabolites on cell-cell separation

Flow cytometry was used to monitor changes in the DNA content of the polychlorinated biphenyl (PCB)-degrading bacterium Comamonas testosteroni TK102 during growth in the presence or absence of PCBs. In culture medium without PCBs, the majority of stationary-phase cells contained a single chromosome. In the presence of PCBs, the percentage of cells containing two chromosomes increased from 12% to approximately 50%. In contrast, addition of PCBs did not change the DNA contents of three species that are unable to degrade PCBs. In addition, highly chlorinated PCBs that are not degraded by TK102 did not result in a change in the DNA content. These results suggest that PCBs did not affect the DNA content of the cells directly; rather, the intermediate metabolites resulting from the degradation of PCBs caused the increase in DNA content. To study the effect of intermediate metabolites on the DNA content of the cells, four bph genes, bphA1, bphB, bphC, and bphD, were disrupted by gene replacement. The resulting mutant strains accumulated intermediate metabolites when they were grown in the presence of PCBs or biphenyl (BP). When the bphB gene was disrupted, the percentage of cells containing two chromosomes increased in cultures grown with PCBs or BP. When grown with BP, cultures of this mutant accumulated two intermediate metabolites, 2-hydroxybiphenyl (2-OHBP) and 3-OHBP. Addition of 2- or 3-OHBP to a wild-type TK102 and non-PCB-degrading species culture also resulted in an increase in the percentage of cells containing two chromosomes. Electron microscopy revealed that cell-cell separation was inhibited in this culture. This is the first report that hydroxy-BPs can inhibit bacterial cell separation while allowing continued DNA replication.     

利用雨养泥炭沼泽及湖泊沉积物重建多氯联苯污染时空变化趋势

为了重建不同历史时期多氯联苯(PCBs)的沉降速率以研究其污染的时空变化趋势,本研究分析了PCBs在泥炭芯和湖泊沉积柱芯中浓度和沉降速率的变化规律,并评估了泥炭芯和湖泊沉积柱芯用于PCBs沉降变化研究的适用性。对采集柱芯进行定年分析发现,泥炭沼泽可以很好地记录PCBs历史沉降变化,并且泥炭中的PCBs没有出现降解情况,因此采用泥炭地研究PCBs沉降变化是可行的。本研究中泥炭地11种多氯联苯同系物(∑₁₁PCBs)的重建时间为19世纪初至21世纪初,对泥炭中PCBs含量检测发现,每个沼泽的3个泥炭芯中∑₁₁PCBs的单位面积埋藏量均值在(37.0±5.4)～(47.2±27.8) μg·m^-2之间变化,标准偏差在14.6%～58.9%,∑₁₁PCBs的最高浓度可达6.8 ng·g^-1DW,重建的PCBs沉降最大速率可达989.7 ng·m^-2·a^-1。沉降速率的变化趋势为先增后减,1980年后明显下降,这与美国在1979年禁止生产PCBs相符。对沼泽附近湖泊的沉积物取样分析发现,湖泊沉积物柱芯各深度所对应的浓度和最大沉降速率与附近沼泽相近。但湖泊沉积物剖面中2～7阶PCBs同系物的浓度分布均匀,表明湖泊沉积物无法用于分析低阶PCBs的历史沉降变化。本研究重建了不同历史时期大气环境中PCBs的时空变化规律,可为评价区域环境质量提供基础资料。     

Effect of polychlorinated biphenyls (PCBs) on basal and OT-stimulated calcium concentrations in myometrial cells in cows

We investigated the effect of PCB-77, -126 or -153 (10 or 100 ng/ml) on free intracellular calcium concentrations([Ca2+]i) in bovine myometrial cells from days 1-5 of the estrous cycle. Cells were incubated with or without PCBs for 48 h (38 degrees C, aerated atmosphere) and thereafter [Ca2+]i was measured by means of fluorescent calcium indicator Fura-2. PCBs increased basal concentrations of [Ca2+]i measured before oxytocin (OT) challenge. The increase in [Ca2+]i in cells incubated with PCBs and challenged with OT was inhibited or delayed when compared to control OT-stimulated cells (p<0.05). The applied doses of PCBs did not affect viability of myometrial cells. In conclusion, the influence of PCBs upon intracellular calcium mobilization in myometrial cells impaired the bovine uterus contractility.     

The role of hydrogen peroxide produced by polychlorinated biphenyls in PMR1-deficient yeast cells

Polychlorinated biphenyls (PCBs) are well-known recalcitrant environmental pollutants. Although the metabolism of the PCBs has been intensively studied, very little is known about their mechanism of toxicity in living organisms or how they are degraded. We have examined the effects of PCBs on two different yeast strains to determine their mechanism of action. One yeast strain (K601, wild type) is resistant to the growth-inhibitory effect of PCBs, whereas the other strain (AA542, PMR1 mutant) is susceptible. PCBs increased the level of intracellular hydrogen peroxide in AA542 cells but not in K601 cells. In the presence of alpha-tocopherol or ursolic acid the growth of AA542 cells was not inhibited by treatment with PCBs. These results suggest that PCBs block cell growth through production of hydrogen peroxide in the PMR1 mutant strain, AA542. We compared superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase activities in both strains. The catalase activity in K601 cells was 10 times higher than that in AA542 cells. In contrast, there was no difference in activities of SOD and GPx between the two strains. Collectively, these observations indicate that oxidative stress causes the inhibition of cell growth observed in catalase-deficient yeast cells exposed to PCBs.     

Sphingobium fuliginis HC3: A Novel and Robust Isolated Biphenyl- and Polychlorinated Biphenyls-Degrading Bacterium without Dead-End Intermediates Accumulation

Biphenyl and polychlorinated biphenyls (PCBs) are typical environmental pollutants. However, these pollutants are hard to be totally mineralized by environmental microorganisms. One reason for this is the accumulation of dead-end intermediates during biphenyl and PCBs biodegradation, especially benzoate and chlorobenzoates (CBAs). Until now, only a few microorganisms have been reported to have the ability to completely mineralize biphenyl and PCBs. In this research, a novel bacterium HC3, which could degrade biphenyl and PCBs without dead-end intermediates accumulation, was isolated from PCBs-contaminated soil and identified as Sphingobium fuliginis. Benzoate and 3-chlorobenzoate (3-CBA) transformed from biphenyl and 3-chlorobiphenyl (3-CB) could be rapidly degraded by HC3. This strain has strong degradation ability of biphenyl, lower chlorinated (mono-, di- and tri-) PCBs as well as mono-CBAs, and the biphenyl/PCBs catabolic genes of HC3 are cloned on its plasmid. It could degrade 80.7% of 100 mg L ⁻¹ biphenyl within 24 h and its biphenyl degradation ability could be enhanced by adding readily available carbon sources such as tryptone and yeast extract. As far as we know, HC3 is the first reported that can degrade biphenyl and 3-CB without accumulation of benzoate and 3-CBA in the genus Sphingobium, which indicates the bacterium has the potential to totally mineralize biphenyl/PCBs and might be a good candidate for restoring biphenyl/PCBs-polluted environments.