[Degradation characteristics of 2,4,6-trichlorophenol by the anaerobic consortium XH-1]. / 厌氧微生物菌群XH-1对2,4,6-ä¸‰æ°¯è‹¯é šçš„é™è§£ç‰¹æ€§.

Organic pollutant 2,4,6-trichlorophenol (2,4,6-TCP) is commonly found in anaerobic environments such as sediments and groundwater aquifers. To investigate the ability of the anaerobic consortium XH-1 to degrade 2,4,6-TCP, we established anaerobic incubations using 2,4,6-TCP as the substrate and inoculated the incubations with XH-1. Additional subcultures were established by amending with intermediate product 4-chlorophenol (4-CP) or phenol as the substrate. The transformation products of 2,4,6-TCP were analyzed and determined using high-performance liquid chromatography (HPLC). Microbial community structure and key microbial groups involved in the degradation of 2,4,6-TCP were analyzed based on 16S rRNA gene high-throughput sequencing. The results showed that the initial 122 µmol·L-1 2,4,6-TCP was completely transformed after a 80-day incubation at a rate of 0.15 µmol·d-1. 2,4-dichlorophenol (2,4-DCP), 4-CP and phenol were identified as the intermediate products. All intermediate products generated from 2,4,6-TCP transformation were completely degraded after being incubated for 325 days. The main microbial groups responsible for the reductive dechlorination of 2,4,6-TCP might be the organohalide respiring Dehalobacter and Dehalococcoides. The subsequent reductive dechlorination of 4-CP to phenol was likely driven by Dehalococcoides. The cooperation between the organohalide respiring bacteria, Syntrophorhabdus and methanogens (e.g. Methanosaeta and Methanofolis) was responsible for the complete degradation of 2,4,6-TCP.

The circular RNA TLK1 exacerbates myocardial ischemia/reperfusion injury via targeting miR-214/RIPK1 through TNF signaling pathway.

PURPOSE: Myocardial ischemia/reperfusion injury (IRI) induces cardiomyocytes death and leads to loss of cardiac function. Circular RNAs (circRNA) have gain increasing interests in modulating myocardial IRI. In this study, we aim to investigate the role and exact mechanism of circTLK1 in the pathogenesis of myocardial IRI. METHODS: Myocardial IRI was developed in mice with measuring hemodynamic parameters and the activity of serum myocardial enzymes to evaluate cardiac function. HE and TTC staining were performed to assess infarct area. Expression patterns of circTLK1 and miR-214 were investigated using qRT-PCR assay. Gene expression of circTLK1, miR-214 or RIPK was altered by transfecting with their overexpression or knockdown vectors. The apoptosis of cardimyocytes was assessed by TUNEL staining and Caspase-3 activity analysis. Apoptosis-related markers Bcl-2, Bax, and caspase3, as well as TNF-α signals were determined by western blotting. The interactions of circTLK1/miR-214 and miR-214/RIPK1 were verified using luciferase reporter assay. RNA immunoprecipitation (RIP) was subjected to further definite the direct binding of circTLK1/miR-214. The regulatory network of circTLK1/miR-214/RIPK1 was further validated in vivo. RESULTS: circTLK1 was an up-regulated circRNA found in a myocardial IRI mouse model. Mice with silencing circTLK1 significantly alleviated the impaired cardiac function indexes and decreased infarct area, thus attenuating the pathogenesis of myocardial IRI. Knockdown of circTLK1 dramatically decreased cardiomyocytes apoptosis, which was determined by apoptosis-related proteins. miR-214 was identified as a downstream effector to reverse circTLK1-mediated damage effects in myocardial IRI. miR-214 could directly target RIPK1 via binding to its' 3'-UTR. Overexpression of RIPK1 led to impaired cardiac function indexes, increased infarct area, and cell apoptosis, which abolished the protective effects of miR-214. The TNF signaling pathway was demonstrated to be involved in the circTLK1/miR-214/RIPK1 regulatory network in myocardial IRI. CONCLUSION: Taken together, our study revealed an up-regulated circRNA, circTLK1, could exacerbate myocardial IRI via targeting miR-214/RIPK1-mediated TNF signaling pathway, which may provide therapeutic targets for treatment.

Effects of organic ligands on Pb absorption and speciation changes in Arabidopsis as determined by micro X-ray fluorescence and X-ray absorption near-edge structure analysis.

Pb can pass through the food chain via plants and threaten human health, which has attracted widespread attention. Changes in Pb speciation affect its bioavailability in soils and water. However, whether organic ligands can change the uptake and mobility of Pb in plants and increase or decrease Pb bioavailability remains uncertain. To reveal the roles of organic and inorganic Pb in Pb metabolism in plants, the localization and speciation changes of Pb in Arabidopsis thaliana plants grown in organic and inorganic Pb were characterized by synchrotron radiation micro X-ray fluorescence and X-ray absorption near-edge structure, respectively. These results demonstrated that Arabidopsis absorbed more Pb from Pb(NO3)2 than Pb(CH3COO)2 at the same exposure concentration. A higher percentage of Pb-citrate was found in Arabidopsis exposed to inorganic Pb solution, which suggested that Pb-citrate was the main complex for root-to-shoot transportation in Arabidopsis exposed to inorganic Pb solutions. Pb complexed with the organic ligand CH3COO- significantly inhibited primary root growth and lateral root development, while, at the same time, Pb was blocked by root hairs, which represented another way to reduce Pb absorption and protect the plant from biotoxicity.

[Impact of PAHs on the expression of PRDX in earthworm (Eisenia fetida)].

A peroxiredoxin6 (PRDX6)-like gene segment has been found in up-regulated cDNA libraries of earthworm Eisenia fetida exposed to benzo[a]pyrene(BaP). Analysis with basic local alignment search tool (BLAST) and phylogenetic analysis revealed that the gene segment contains a characteristic motif which was encoded by Cys, illustrating that this gene segment belongs to PRDX. To verify the response of PRDX in E. feitida exposed to poly aromatic hydrocarbons (PAHs), four-week pollution experiments were conducted following the methods recommended by the Organization for Economic Co-operation and Development (OECD). The results showed that the expression of PRDX was up-regulated in earthworm exposed to 1.0 mg x kg(-1) Pyrene and BaP. It was indicated that PRDX in E. fetida was the potential molecular biomarkers of antioxidative stress caused by soil contamination.

Composition, sources, and potential toxicology of polycyclic aromatic hydrocarbons (PAHs) in agricultural soils in Liaoning, People's Republic of China.

Surface soil (0-20 cm) samples (n = 143) were collected from vegetable, maize, and paddy farmland used for commercial crops in Liaoning, China. Sixteen priority polycyclic aromatic hydrocarbons (PAHs) listed in US Environmental Protection Agency were analyzed by high-performance liquid chromatography using a fluorescence detector. The soil concentrations of the 16 PAH ranged from 50 to 3,309 ng/g with a mean of 388 ng/g. The highest concentration of total PAHs found in soil of the vegetable farmland was 448 ng/g in average, followed by maize and paddy with total PAHs of 391 and 331 ng/g, respectively. Generally, the low molecular weight PAHs were more predominant than the high molecular weight PAHs in most of the soils. The evaluation of soil PAH contamination based on the Canadian criterion indicated that only naphthalene, phenanthrene, and pyrene were over the target values in several sampling sites. Isomer pair ratios and principal component analysis indicated that biomass and coal combustion were the main sources of PAHs in this area. And the average value of total B[a]Peq concentration in vegetable soils was higher than paddy and maize soils. We suggest that biomass burning should be abolished and commercial farming should be carried out far from the highways to ensure the safety of food products derived from commercial farming.

[Assessment of toxicity effects for cadmium contamination in soils by means of multi-indexes].

The genetic and eco-toxic effects of Cd (0-10 mg x kg(-1)) were studied with Vicia faba (broad bean) as the test species using meadow brown soil in pot experiments by means of several indexes, such as Vicia faba root tip micronucleus frequency (MCN), mitosis index (MI), and chromosomal aberrations frequency (CAF), antioxidant enzymes superoxide dismutases (SOD), peroxidases (POD), catalase (CAT) and phytohormone abscisic acid (ABA), gibberellic acid (GA3) and zeatin and zeatin riboside (Z&ZR). Results indicated the significant positive dose-response correlations were found between Cd2+ concentrations and the tested indexes (MI, MCN and CAF). Among of them, MCN is the most sensitive, and the MCN frequencies were 1.43-3.22 times higher in Cd treatment soils than that of in the controls. SOD and POD in seedling leaves of broad bean were response to the Cd stress, showing a trend of increase with Cd concentrations initially and then decreased. The CAT response to Cd in soils was opposite to that of SOD and POD. In addition, there were stimulation and inhabitation effects between Cd and ABA, GA3 and Z&ZR in lower and higher Cd concentrations. The highest contents of phytohormone (ABA, GA3 and Z&ZR) were found when Cd was at 2.5 mg x kg(-1), which was 6.6%, 4.0% and 12.6% higher than that in the control, respectively. Our study indicated that all indexes were response to the Cd stress in soils, but the sensitivity of each index was different from each other. All these indexes combined should be more efficiency in the diagnosis of geno-, and eco-toxicity of cadmium in soils.

[Impact of benzo [a] pyrene the expression of mitochondrion-encoded genes in the earthworm Eisenia fetida].

The earthworm Eisenia fetida's benzo [a] pyrene (BaP) exposure experiments were carried out in artificial soil according to ISO 11268-1:1993. And then the upregulated and downregulated subtractive cDNA libraries were constructed by Clontech PCR-Select cDNA Subtration Kit. From the BaP exposure upregulated subtractive cDNA library, several cDNA segments matched mitochondrion-encoded genes were found, including cytochrome c oxidase subunit I (CO I), subunit II (CO II), subunit Ill (CO III), NADH dehydrogenase subunit 1 (NDH1), and ATP synthase subunit 6. The result indicated BaP and the subsequent oxidative stress disturbed the expression of mitochondrion-encoded genes, and this was potential biomarker for oxidative stress following xenobiotic exposure.

[Low dose benzo(a)pyrene up-regulated the transcription of HSP70 and HSP90 in Eisenia fetida].

To search for the molecular biomarkers of sub-lethal polycyclic aromatic hydrocarbons (PAHs)-contamination of soil, the subtractive cDNA libraries of earthworm Eisenia fetida exposed to benzo(a)pyrene (BaP) in artificial soil were constructed by suppression subtractive hybridization. After sequencing and analyzing with basic local alignment search tool (BLAST), two clones matching heat shock protein 70 k Da (HSP70) and one clone matching heat shock protein 90 k Da (HSP90) were isolated from the up-regulated library, and subsequently, the up-regulation of HSP70 and HSP90 was verified by real-time PCR in E. fetida exposed to 0.1 mg x kg(-1) and 1.0 mg x kg(-1) BaP. It was indicated that these two newly identified HSPs in E. fetida were the potential molecular biomarkers for soil contamination monitoring.

[Effects of low dosage pyrene pollution on biochemical characters of earthworm (Eisenia fetida) in soil].

By the method of artificial soil pollution, an exposure experiment with different concentrations of pyrene (0, 60, 120, 240, 480, 960 microg x kg(-1)) was conducted to determine the cytochrome P450 and MDA contents and the glutathione-S-transferase (GST), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities in earthworm gut after exposure for 1, 3, 7 and 14 days. The results indicated that within the range of test pyrene concentrations, all the biochemical indices tested differed in their sensitivity to pyrene toxicity, among which, P450 content and GST and SOD activities were most sensitive, followed by POD and CAT activities, while MDA content did not show any obvious response. Exposure duration had stronger effects than exposure dosage. In diagnosing the ecotoxicity of soil pollutant, it could be necessary to use a combined multi-time and multi-index diagnostic method to enhance the sensitivity and effectiveness of the indices adopted.

[Dose-response relationships between endogenous phytohormones of high plant and concentrations of fluoranthene and benzo(a)pyrene in soils].

By means of indoor pot experiment, three phytohormones, gibberellic acid (GA3), zeatin and zeatin riboside (Z&ZR), abscisic acid (ABA) of wheat ( Triticum acstivnm) were measured under the stress of fluoranthene and benzo(a)pyrene in meadow brown soil singlely and combinedly. The results indicated that significant dose-response relationship was observed between ABA contents and the concentrations of single fluoranthene and combined pollution of fluoranthene and benzo(a)pyrene, and ABA content responded more intensive to single fluoranthene than to combined treatment. When treated with 16 mg x kg(-1) single fluoranthene, ABA content increased by 198% as compared with control. Significant effects on GA3 content of combined treatment were also observed, but GA3 responded insensitively to single fluoranthene and benzo(a)pyrene treatment. Z&ZR responded intensively under stress of both single and combined pollution, and the inducible effects were accordant. It can be concluded that endogenous phytohormones play an important role in indicating PAHs polluted soil, and the sensitivity of the three phytohormones responded to fluoranthene and benzo(a)pyrene single and combined pollution is in the sequence: Z&ZR > ABA > GA3.

[Establishment of method for cytochrome P450 of earthworms (Eisenia fetida) as a biomarker].

Earthworm (Eisenia fetida) was chosen as test soil fauna to establish the method for determination of cytochrome P450 content. By means of thoroughly washing with salt solution, changing centrifugal acceleration and dissolving microsomal membranes of earthworms with sodium cholate, the determination of cytochrome P450 was performed. Base on the method, dynamic relationships of dose-response for cytochrome P450 contents in earthworm and phenanthrene concentrations were conducted by contact filter paper and soil contaminated with phenanthrene. Results indicate that cytochrome P450 are covered up by interferential material in earthworm, which makes the classic peak lag and appear at 455 - 457nm in the CO difference spectrum with a spectrophotometer. Through increasing centrifugal acceleration and adding reagent of solubilization, the interference is removed mostly and the classic peak of P450 returns to appear at 450nm +/- 1nm. The exposure tests of phenanthrene with contact filter paper (10(-6), 10(-5), 10(-4), 10(-3) and 10(-2) mg x mL(-1)) and soil (1, 2, 4 and 8 mg x kg(-1)) reveal that the dose-response relationships exist between the pollutant and cytochrome P450. Soil tests of different exposure durations (1, 3, 7, 14 and 28d) show the effects of different phenanthrene concentration on earthworm cytochrome P450 contents are to activate (7d) and to inhibit (14d and 28d), and the content of P450 is 0.99 - 1.41 and 0.77 - 0.88 (p < 0.05) times of control respectively. From this study, cytochrome P450 content of earthworm has the merit of simpleness, speediness and economy for determination, and it could be used as a sensitive biomarker for monitoring the exposure of sublethal pollution in terrestrial ecosystem.

[Soil-based eco-toxicity of petroleum to terrestrial higher plant after phytoremediation].

Petroleum-contaminated soil after five-year phytoremediation was taken as tested soil initially spiked with a serial diesel concentration of 5 000, 15 000 and 30 000 mg/kg (dry weight). Residual concentrations of mineral oil by chemical analysis of gravimetry, as well as the soil-based eco-toxicity to wheat (Triticum aestivum L.), the terrestrial higher plant by several ecotoxicological bioassays including seed germination and root elongation test, early seedling growth test, contents of cytochrome P450 monooxygenases, activities of antioxidant enzymes (superoxide dismutase, SOD, and peroxidase, POD), and lipid peroxide (malondialdehyde, MDA content in wheat seedling leaves, etc. were evaluated. Results showed that mineral oil was well removed in each treatment by chemical analysis, with residual concentrations ranging from 199 to 877 mg/kg (dry weight) and with total removal rates between 90.1% and 97.2%. The evaluating results by eco-toxicological assays differed to some extent from those by chemical analysis, meanwhile, eco-toxicity of each treatment differed depending on endpoints by different bioassays. Among the ecotoxicological indexes, root length (48 h), root fresh weight (7 d), contents of P450, activities of SOD, and contents of MDA, etc. exhibited better indication to the soil toxicity. The general evaluation by combining the two analyses chemical and eco-toxicological indicated that the ecological risk was higher in most intermediately- and heavily-contaminated treatments (initially spiked with diesel concentration of 15,000 mg/kg and 30,000 mg/kg).

Phytotoxicity assessment of phenanthrene, pyrene and their mixtures by a soil-based seedling emergence test.

Seedling emergence tests were conducted in a meadow brown soil using five plant species (i.e., Chinese cabbage, green onion, tomato, turnip and wheat) to determine the phytotoxicity of phenanthrene, pyrene and their mixtures. The soil was amended with up to 1000 mg/kg soil of phenanthrene or 600 mg/kg soil of pyrene. Seedling emergence and root growth were measured. The results indicated that root elongation was more sensitive than seedling emergence. Root length decreased with increasing phenanthrene or pyrene concentrations( p < or = 0.05). Phenanthrene was more phytotoxic than pyrene. The lowest observable adverse effect concentration (LOAEC) was 10 mg/kg for phenanthrene when tested with green onion, and 50 mg/kg for pyrene when tested with wheat. Among the five species, wheat was found to be the most sensitive. When amended jointly at or below their respective LOAEC, phenanthrene and pyrene produced a synergistic toxic effect.

[Evaluation of eco-toxicity of integral quality of soils].

Soil samples are collected from several sites along the wastewater irrigation channel, western Shenyang. The concentration of heavy metal(Cd)and mineral oil is analyzed. The eco-toxicity of soil is evaluated. Heavy metal (Cd) isdetermined by atom adsorption spectrometer(AAS), mineral oil is measured by UV spectrometer. The eco-toxicity of soil is based on the method of international standardization of organization (ISO) and OECD guideline with some modification. With inhibition rates of root elongation of wheat as endpoint seed germination test was performed and the duration period was 50h. With lethal and sub-lethal effects as endpoint earthworms test was conducted and the experimental period was 28d. And micronuclear( MCN) test was conducted. Results show the mineral oil in soils were 145 mg/kg - 1 121mg/kg, Cd was 0.34mg/kg - 1.81mg/kg. The inhibition rate of root elongation based on germination test was 2.0% - 35.1%, MCN in soil was significant higher than that in the control. The mortality rates of earworms were 0% - 40%. The inhibition rates of body weight growth were -2.3 % to -19.4% from 14d to -2.1% - 10.7% in 28d. The maximum value of MCN in soils was 6.62/100. The study indicates a lower accumulation of pollutants in soils but enhanced ecotoxicity.

Potential of weed species applied to remediation of soils contaminated with heavy metals.

To screen out a series of ideal plants that can effectively remedy contaminated soils by heavy metals is the main groundwork of phytoremediation engineering and the first step of its commercial application on a large scale. In this study, accumulation and endurance of 45 weed species in 16 families from an agricultural site were in situ examined by using the pot-culture field experiment, and the remediation potential of some weed species with high accumulation of heavy metals was assayed. The results showed that Solanum nigrum and Conyza canadensis can not only accumulate high concentration of Cd, but also strongly endure to single Cd and Cd-Pb-Cu-Zn combined pollution. Thus 2 weed species can be regarded as good hyperaccumulators for the remediation of Cd-contaminated soils. Although there were high Cd-accumulation in Artemigia selengensis, Znula britannica and Cephalanoplos setosum, their biomass was adversely affected due to action of heavy metals in the soils. If the problem of low endurance to heavy metals can be solved by a reinforcer, 3 weed species can be perhaps applied commercially.

[Biodegradation of aromatic hydrocarbons and dynamics of microbe growth in soils contaminated with mineral oil].

Some bacteria and fungi selected from brown soil contaminated with petroleum were taken as test microbes. Degradation of mineral oil, by different combinations of microbes and the correlation between the degradation rate and microbial growth were studied. The bacteria and fungi were inoculated to a liquid substrate spiked with 1000 milligrams diesel-oil per liter. The temperature of rocking-bed was controlled at 25 to 30 centigrade and the experiment continued for 100 days. From 0 to 60 hours it was sampled continuously to monitor the dynamic of microbial growth, and sampled termly from 5 to 100 days to study the growth of microbes and the dynamic of degradation rate. At the same time, the suspension of 0 to 20 centimeters of topsoil of the meadow umber was taken as soil microbial control, and the culture without microbes as blank control. Results showed that degradation effect of the introduced microbes were superior to that of the indigenous microbes in short term (about 20 days), while the advantage of indigenous microbes got stronger and stronger, and the predominance maintained until the experiment was stopped. At the end of the experiment the degradation rate in the treatment of indigenous microbes reached 79.24%, which was above the results of other 3 treatments, and the difference was significant.

[Issues concerned with the bioremediation of contaminated soils].

Several issues faced in the process of bioremediation were discussed in this paper, which are included as below: The principal and condition for the introducing of foreigner microbial; Mechanisms of suitability for microorganisms in the bioremediation process and the factors that influenced the degradation of pollutants; The correlations between the concentration of pollutants and their bioremediation; The secondary pollutants in the process of degradation of organic chemicals; The technology amplification of bioremediation technique on situ or/and in situ; the leaching process of contaminants; The Eco-toxicological diagnosis and evaluation for bioremediation technology and so on in order to enhance the realization for problems existed in the process of bioremediation and make it possible for more effective application of the bioremediation technology.