Expression in Escherichia coli of Biphenyl 2,3-Dioxygenase Genes from a Gram-Positive Polychlorinated Biphenyl Degrader,Rhodococcus jostii RHA1

Rhodococcus jostii RHA1 is a polychlorinated biphenyl degrader. Multi-component biphenyl 2,3-dioxygenase (BphA) genes of RHA1 encode large and small subunits of oxygenase component and ferredoxin and reductase components. They did not express enzyme activity in Escherichia coli. To obtain BphA activity in E. coli, hybrid BphA gene derivatives were constructed by replacing ferredoxin and/or reductase component genes of RHA1 with those of Pseudomonas pseudoalcaligenes KF707. The results obtained indicate a lack of catalytic activity of the RHA1 ferredoxin component gene, bphAc in E. coli. To determine the cause of inability of RHA1 bphAc to express in E. coli, the bphAc gene was introduced into Rosetta (DE3) pLacI, which has extra tRNA genes for rare codons in E. coli. The resulting strain abundantly produced the bphAc product, and showed activity. These results suggest that codon usage bias is involved in inability of RHA1 bphAc to express its catalytic activity in E. coli.     

A novel reductive graphene oxide‐based magnetic molecularly imprinted poly(ethylene‐co‐vinyl alcohol) polymers for the enrichment and determination of polychlorinated biphenyls in fish samples

The novel reductive graphene oxide‐based magnetic molecularly imprinted poly(ethylene‐co‐vinyl alcohol) polymers (rGO@m‐MIPs) were successfully synthesized as adsorbents for six kinds of polychlorinated biphenyls (PCBs) in fish samples. rGO@m‐MIPs was prepared by surface molecular imprinting technique. Besides, Fe₃O₄ nanoparticles (NPs) were employed as magnetic supporters, and rGO@Fe₃O₄ was in situ synthesis. Different from functional monomer and cross‐linker in traditional molecularly imprinted polymer, here, 3,4‐dichlorobenzidine was employed as dummy molecular and poly(ethylene‐co‐vinyl alcohol) was adopted as the imprinted polymers. After morphology and inner structure of the magnetic adsorbent were characterized, the adsorbent was employed for disperse solid phase extraction toward PCBs and exhibited great selectivity and high adsorption efficiency. This material was verified by determination of PCBs in fish samples combined with gas chromatography‐mass spectrometry (GC‐MS) method. According to the detection, the low detection limits (LODs) of PCBs were 0.0035–0.0070 µg l⁻¹ and spiked recoveries ranged between 79.90 and 94.23%. The prepared adsorbent can be renewable for at least 16 times and expected to be a new material for the enrichment and determination of PCBs from contaminated fish samples. Copyright © 2015 John Wiley & Sons, Ltd.     

Neurobehavioral Effects in Relation to Endocrine Alterations Caused by Exposure to Brominated Flame Retardants in Rats—Comparison to Polychlorinated Biphenyls

The widespread use of brominated flame retardants (BFRs) has led to increasing concentrations in environmental samples. Previous reports suggested endocrine activity of these compounds. Because thyroid hormones and sex steroids are known to regulate the development of the nervous system, we examined neurobehavioral and endocrine effects of gestational exposure to 2,2′4,4′,5-pentabrominated diphenyl ether (PBDE99) and lifetime exposure to tetrabromobisphenol A (TBBPA) or hexabromocyclododecane (HBCD) in rats. Treatment with PBDE99 (0, 1, or 10 mg/kg bw) reduced serum testosterone and estradiol in male offspring and affected sexual development in both sexes. Exposed males exhibited increased sweet preference, indicating feminization of this sexually dimorphic behavior. In TBBPA and HBCD experiments, a benchmark design was used with dose ranges of 0-3000 mg/kg bw/day and 0–100 mg/kg bw/day, respectively. Because thyroid hormones are critical for auditory development, brainstem auditory evoked potentials (BAEPs) were recorded in young adult offspring. TBBPA exposure elevated BAEP thresholds in females and prolonged latencies in both sexes. Benchmark doses were comparable for auditory effects and decreased plasma T4. HBCD increased BAEP thresholds and delayed BAEP waves only in males, but the relation to thyroid hormones remains to be determined. HBCD also reduced latencies in haloperidol-induced catalepsy, suggesting effects on the dopaminergic system.     

Microbial Degradation of Organic Pollutants in Soil in a Cold Climate

Cold-adapted microorganisms are potentially interesting for use in environmental biotechnology applications since a large part of the biosphere has low temperatures during at least parts of the year. Many studies have shown that both oil-contaminated and uncontaminated soils in the Arctic, the Antarctic and the Alps contain microbes that can degrade different hydrocarbons deriving from oils. A few studies have also been conducted on degradation of herbicides in soils at low temperatures. Furthermore, phenols and some polychlorinated biphenyl (PCB) congeners have proved to be degradable at low temperatures, using microorganisms isolated from sediments or soils. Additions of nitrogen and phosphorous to polluted soils have been shown to enhance the degradation of hydrocarbons in many cases. Bioaugmentation with hydrocarbon degrading cold-adapted microorganisms has given varying results. The inoculated microorganisms have probably been out-competed by the indigenous microorganisms in some cases. Different ways to increase the efficiency of microbial degradation of organic pollutants in soil in a cold climate is discussed.     

珠江三角洲池塘养殖中多氯联苯的环境归趋

对珠江三角洲4个不同地方的养殖池塘中水样,泥样和不同种类的鱼样分析,结果表明水产养殖中多氯联苯的分布和归趋在不同分配相中有很大差别,水相中含量较低(8.0～2 4 .0 3ng·L- 1 ) ,沉积相中较高(7.32～36 .2 3ng·g- 1 ,干重) ,特别是工业活动频繁的地方,而乡村相对较低。鱼类不同食性对多氯联苯的积累及其同分异构体的分布有很大影响,肉食性鱼类比草食性鱼类积累更多的多氯联苯.其中代表性同分异构体有IUPAC 118,138,81/ 87,15 3,180 ,5 2 ,4 9,99,4 4。珠江三角洲水产养殖中多氯联苯对生态环境的影响相对较低。     

The Effect of Mycorrhizal Fungi on the Fate of PCBs in Two Vegetated Systems

The objective of this study was to investigate the effects of mycorrhizal infection on vegetative uptake of polychlorinated biphenyls. Feltleaf willow (Salix alaxensis) and balsam poplar (Populus balsamifera) were grown in soil spiked with 6 mg/kg 3,3′,4,4′-tetrachlorobiphenyl-(UL-¹⁴C). The fungicide Daconil₂₇₈₇® was employed to suppress indigenous mycorrhizal infection. After 100 days of greenhouse incubation in semienclosed phytoreactors, mycorrhizal infection was found to be approximately threefold higher in the untreated willows vs. the fungicide-amended willows. Radio-label uptake was found to correlate most highly with mycorrhizal infection in the willow roots (R = 0.83). Over the same time period, mycorrhizal infection in the poplars was not significantly affected by fungicide addition. In the poplar phytoreactors, radiolabel uptake was most highly correlated with water use (R = 0.70). The overall vegetative radiolabel uptake was low (≈ 1%), but the limited uptake was attributed to soil sorption processes rather than vegetative limitations.     

Some Aspects of PCB Metabolism by Horseradish Cells

Transformation of polychlorinated biphenyls was studied using different strains of in vitro cultured cells of horseradish (Armoracia rusticana L.). Time and concentration dependence of this process and production of intracellular and extracellular peroxidases were measured with differentiated shooty teratoma culture K54. The yield of PCB transformation and the viability of the cells were highly dependent on PCB concentration. 100 ppm PCB totally inhibited growth of the cells, and reduced their metabolism of xenobiotics. Experiments with a peroxidase (POX) inhibitor, propylgallate, and a cytochrome P450 inhibitor, aminobenztriazole, indicated the involvement of both enzymatic systems in PCB metabolism.     

Field Studies Using European Starlings to Establish Causality between PCB Exposure and Reproductive Effects

Accumulation and effects of polychlorinated biphenyls (PCBs) in avian species were evaluated at a Superfund site located at Crab Orchard National Wildlife Refuge, Illinois, and seven criteria were used to assess whether there was a causal relationship between PCB exposure and observed reproductive effects. European starlings (Sturnus vulgaris) were monitored at nest boxes constructed at each of two exposed and two reference sites. During the breeding season, starling productivity (number of chicks produced per nest) and adult nest attentiveness behavior (provisioning behavior) were monitored. At 15 days post-hatch, chicks were collected for contaminant and biomarker analyses. Chicks were necropsied, ethoxyresorufin-O-deethylase (EROD) activity measured in liver tissue, and PCB (Aroclor 1254) and 34 chlorinated biphenyl (CB) congener concentrations measured in carcasses using gas chromatography. PCB and CB concentrations also were measured in eggs that failed to hatch. Mean Aroclor 1254 and quantified CB concentrations were greater (P<0.001) in eggs that failed to hatch and 15-day-old chicks collected from PCB sites compared to those collected from reference sites. EROD activity was greater (P=0.005) in 15-day-old chicks collected from PCB sites and was correlated with carcass PCB concentrations. Reduced adult nest attentiveness behavior and decreased chick survival were observed at PCB sites. Six of the seven causal criteria evaluated provided evidence that observed reproductive effects resulted from exposure to PCBs. Using this weight-of-evidence approach provided a means for establishing the likely cause of effects and thus provided managers with information needed in decision-making processes.     

Polychlorinated biphenyls in vegetable soils from Changchun,Northeast China: Concentrations,distribution, sources and human health risks

To investigate the occurrences of polychlorinated biphenyls (PCBs) in suburban vegetable soils of Changchun area, Northeast China, 106 urban vegetable soil samples were collected from Changchun City, Nongan County, Dehui City, Yushu City, Jiutai City, Shuangyang District. We analyzed the concentrations, compositions and sources of 7 PCBs in top soils of Changchun area, and evaluated the non-carcinogenic and carcinogenic risk of PCBs pollution to exposed population. The total concentrations of 7 PCBs ranged from 1.31 to 148 ng/g dry weight (dw) with a mean value of 42.0 ng/g and dominated by Hepta-CBs and Penta-CBs. Principal component analysis (PCA) revealed that PCB pollution in soils of Changchun area mainly related to transportation, vehicle emissions, paints and other industries. Human health risk assessment showed that the cumulative non-carcinogenic and the cumulative carcinogenic risk in children and adults in the industrial land and residential land were acceptable, considering only 7 PCBs homologues were analyzed in this study, the actual risk could be higher.     

Glutamate antagonism fails to reverse mitochondrial dysfunction in late phase of experimental neonatal asphyxia in rats

Because estrogen plays important neurotrophic and neuroprotective roles in the brain by activating estrogen receptors (ERs), disruption of normal estrogen signaling can leave neurons vulnerable to a variety of insults, including β-amyloid peptide (Aβ). Aroclor1254 (A1254) belongs to the endocrine-disrupting chemical (EDC) polychlorinated biphenyls and has anti-estrogenic properties. In the present study, we evaluated the effect of A1254 on the protective activity of estrogen against Aβ toxicity in differentiated cholinergic SN56 cells. Aged Aβ25-35 causes apoptotic cell death in differentiated SN56 cells, and the cytotoxic evidences are effectively rescued by estrogen. We found that A1254 abolishes the neuroprotective activity of estrogen against Aβ toxicity, and attenuates the suppressive effect of estrogen on Aβ-induced tau phosphorylation and JNK activation. The effects of A1254 on the neuroprotective effects of estrogen in Aβ toxicity are very similar to the effects of the estrogen receptor antagonist ICI182,780. Thus, exposure to EDCs that have anti-estrogenic activity might interfere with normal estrogen-activated neuroprotective signaling events and leave neurons more vulnerable to dangerous stimuli. Our present results provide new understanding of the mechanisms contributing to the harmful effects of EDCs on the function and viability of neurons, and the possible relevance of EDCs in the pathogenesis of neurodegenerative diseases such as Alzheimer’s disease.