Natural and Technical Phytoremediation of Oil-Contaminated Soil.

Natural and technical phytoremediation approaches were compared for their efficacy in decontaminating oil-polluted soil. We examined 20 oil-contaminated sites of 800 to 12,000 m2 each, with different contamination types (fresh or aged) and levels (4.2-27.4 g/kg). The study was conducted on a field scale in the industrial and adjacent areas of a petroleum refinery. Technical remediation with alfalfa (Medicago sativa L.), ryegrass (Lolium perenne L.), nitrogen fertilizer, and soil agrotechnical treatment was used to clean up 10 sites contaminated by oil hydrocarbons (average concentration, 13.7 g/kg). In technical phytoremediation, the per-year decontamination of soil was as high as 72-90%, whereas in natural phytoremediation (natural attenuation with native vegetation) at 10 other oil-contaminated sites, per-year decontamination was as high as that only after 5 years. Rhizodegradation is supposed as the principal mechanisms of both phytoremediation approaches.

Effect of remediation techniques on petroleum removal from and on biological activity of a drought-stressed Kastanozem soil.

Many petroleum extraction and refinement plants are located in arid climates. Therefore, the remediation of petroleum-polluted soils is complicated by the low moisture conditions. We ran a 70-day experiment to test the efficacy of various combining of remediation treatments with sorghum, yellow medick, and biochar to remove petroleum from and change the biological activity of Kastanozem, a soil typical of the dry steppes and semideserts of the temperate zone. At normal moisture, the maximum petroleum-degradation rate (40%) was obtained with sorghum-biochar. At low moisture, the petroleum-degradation rate was 22 and 30% with yellow medick alone and with yellow medick - sorghum, respectively. Biochar and the biochar-plant interaction had little effect on soil remediation. Both plants promoted the numbers of soil microbes in their rhizosphere: yellow medick promoted mostly hydrocarbon-oxidizing microorganisms, whereas sorghum promoted both hydrocarbon-oxidizing and total heterotrophic microorganisms. Low moisture did not limit microbial development. In the rhizosphere of sorghum, dehydrogenase and urease activities were maximal at normal moisture, whereas in the rhizosphere of yellow medick, they were maximal at low moisture. Peroxidase activity was promoted by the plants in unpolluted soil and was close to the control values in polluted soil. Biochar and the biochar-plant interaction did not noticeably affect the biological activity of the soil.

Chronic morphine intoxication reduces binding of HuD to BDNF long 3'-UTR, while morphine withdrawal stimulates BDNF expression in the frontal cortex of male Wistar rats.

BACKGROUND: Brain-derived neurotrophic factor (BDNF) mediates opiate dependence phenomenon. In the brain of morphine dependent animals BDNF level is controlled transcriptionally, however, post-transcriptional mechanisms of BDNF regulation in this context remain unknown. Regulation of mRNA by binding of specific proteins to the 3'-untranslated region (3'-UTR) is one of such mechanisms. Among RNA-binding proteins neuronal Hu antigen D (HuD) is the best characterized positive regulator of BDNF, however its involvement in opiate dependence remains obscure. We suggested that HuD binding to the BDNF 3'-UTR may be linked to changes in BDNF expression induced by morphine. The aim of this study was to investigate potential association of HuD with BDNF 3'-UTR in relation to BDNF expression (Exon- and 3'-UTR-specific mRNA variants and protein level) in the frontal cortex and midbrain of male Wistar rats after chronic morphine intoxication and spontaneous withdrawal in dependent animals. RESULTS: After chronic morphine intoxication but not during morphine withdrawal HuD binding to the long BDNF 3'-UTR in the frontal cortex decreased as compared with the corresponding control group, however after intoxication BDNF expression did not change. The level of BDNF Exon I as well as mature BDNF polypeptide increased in the frontal cortex upon morphine withdrawal, while no changes in HuD binding could be detected. CONCLUSION: Thus, contrary to the assumption, HuD-BDNF 3'-UTR interaction and BDNF expression in the frontal cortex differentially change in a manner dependent on the context of morphine action.

Study of Boraginaceae plants for phytoremediation of oil-contaminated soil.

Long-term field observations of the natural vegetation cover in industrial and adjacent areas has revealed that the Boraginaceae was one of the main plant family representatives of which were noted in oil-contaminated area. In this study against the background of the previously well characterized plant families Poaceae and Fabaceae, the phytoremediation potential of Boraginaceae plants was investigated under the field conditions and described. Among the members of this family, Lithospermum arvense, Nonea pulla, Asperugo procumbens, Lappula myosotis, and Echium vulgare were the most common in oil-contaminated areas. N. pulla was the most tolerant to hydrocarbons and, along with L. arvense and E. vulgare, actively stimulated the soil microorganisms, including hydrocarbon-oxidizing ones, in their rhizosphere. A comparative assay confirmed that the plants of the Fabaceae family as a whole more efficiently enrich the soil both with available nitrogen and with pollutant degradation genes. Nevertheless, the comparatively high ammonium nitrogen content in the rhizosphere of N. pulla and E. vulgare allows these species to be singled out to explain their high rhizosphere effect, and to suggest their remediation potential for oil-contaminated soil.Novelty statement Against the background of the previously well characterized plant families Poaceae and Fabaceae, the remediation potential of Boraginaceae plants was described for the first time. Overall, this study contributes to understanding the differences in remediation potential of plants at the family level and suggests the monitoring pollutant degradation genes as an informative tool to the search for plant promising for use in the cleanup of oil-contaminated soil.

Mycolicibacterium sp. strain PAM1, an alfalfa rhizosphere dweller, catabolizes PAHs and promotes partner-plant growth.

This research was focused on the isolation and characterization of a PAH-catabolizing mycobacterial strain from the petroleum hydrocarbon-contaminated rhizosphere of alfalfa, as well as on revealing some points of interaction between the microorganism and the plant. Mycolicibacterium sp. PAM1, a pyrene degrader isolated from the niche of interest to us, can catabolize fluoranthene, anthracene, fluorene, and phenanthrene. On the basis of curves of PAM1 growth with different PAHs as the sole carbon sources and on the basis of PAH-degradation rates, we found that pollutant availability to the strain decreased in the sequence phenanthrene > fluorene > fluoranthene ∼ pyrene > anthracene. For each PAH, the catabolic products were identified. PAM1 was found to have the functional genes nidA and nidB. New data modeling the 2D and 3D structures, intrinsic structural disorder, and molecular dynamics of the nidA and nidB gene products were obtained. The identified genes and intermediates of pyrene degradation indicate that PAM1 has a PAH catabolic pathway that is peculiar to known mycobacterial pyrene degraders. PAM1 utilized some components of alfalfa root exudates as nutrients and promoted plant growth. The use of mycobacterial partners of alfalfa is attractive for enhancing the phytoremediation of PAH-contaminated soils.

Dynamics of natural revegetation of hydrocarbon-contaminated soil and remediation potential of indigenous plant species in the steppe zone of the southern Volga Uplands.

The result of monitoring of natural vegetation growing on oil-contaminated (2.0-75.6 g/kg) and uncontaminated (0.04-2.0 g/kg) soils of a petroleum refinery for a period of 13 years is presented. Floristic studies showed that the families Poaceae, Asteraceae, Fabaceae, and eventually Brassicaceae were predominant in the vegetation cover of both types of soils. Over time, the projective vegetation cover of the contaminated sites increased from 46 to 90%; the species diversity increased twofold: in the ecological-cenotic structure of the flora, the number of ruderal plant species decreased; and the number of steppe, i.e., zonal, plant species increased. Using 62 dominant plant species, we conducted a field study of plant characteristics such as resistance to oil pollution, the ability to enrich the rhizosphere soil with microorganisms and bioavailable mineral nitrogen, and reduction of the concentration of petroleum hydrocarbons. The results enable us to characterize the phytoremediation potential (PRP) of the native plants and identify species that, probably, played a key role in the natural restoration of oil-contaminated soils. Statistical analysis showed correlations between the PRP constituents, and the leading role of rhizosphere microorganisms in the rhizodegradation of petroleum hydrocarbons was proven. A conditional value of PRP was proposed which allowed the investigated plants to be ranked in 11 classes. The study of a large sample of plant species showed that some plants held promise for the use in reclamation of soils in arid steppe zone, and that other species can be used for the rehabilitation of saline soils and semideserts.

Comparison of the phytoremediation potentials of Medicago falcata L. And Medicago sativa L. in aged oil-sludge-contaminated soil.

Thirteen-year monitoring of the vegetation growing in the industrial and adjacent areas of an oil refinery showed the prevalence of yellow medick (Medicago falcata L.) over other plant species, including alfalfa (Medicago sativa L.). A comparative field study of the two Medicago species established that yellow medick and alfalfa exhibited similar resistance to soil petroleum hydrocarbons and that the pollutant concentration in their rhizosphere was 30% lower than that in the surrounding bulk soil. In laboratory pot experiments, yellow medick reduced the contaminant content by 18% owing to the degradation of the major heavy oil fractions, such as paraffins, naphthenes, and alcohol and benzene tars; and it was more successful than alfalfa. Both species were equally effective in stimulating the total number of soil microorganisms, but the number of hydrocarbon-oxidizing microorganisms, including polycyclic aromatic hydrocarbon degraders, was larger in the root zone of alfalfa. In turn, yellow medick provided a favorable balance of available nitrogen. Both Medicago species equally stimulated the dehydrogenase and peroxidase activities of the soil, and yellow medick increased the activity of soil polyphenol oxidase but reduced the activity of catalase. The root tissue activity of catalase, ascorbate oxidase, and tyrosinase was grater in alfalfa than in yellow medick. The peroxidase activity of plant roots was similar in both species, but nondenaturing polyacrylamide gel electrophoresis showed some differences in the peroxidase profiles of the root extracts of alfalfa and yellow medick. Overall, this study suggests that the phytoremediation potentials of yellow medick and alfalfa are similar, with some differences.

Expression of BDNF and TrkB Phosphorylation in the Rat Frontal Cortex During Morphine Withdrawal are NO Dependent.

Nitric oxide (NO) mediates pharmacological effects of opiates including dependence and abstinence. Modulation of NO synthesis during the induction phase of morphine dependence affects manifestations of morphine withdrawal syndrome, though little is known about mechanisms underlying this phenomenon. Neurotrophic and growth factors are involved in neuronal adaptation during opiate dependence. NO-dependent modulation of morphine dependence may be mediated by changes in expression and activity of neurotrophic and/or growth factors in the brain. Here, we studied the effects of NO synthesis inhibition during the induction phase of morphine dependence on the expression of brain-derived neurotrophic factor (BDNF), glial-derived neurotrophic factor (GDNF), nerve growth factor (NGF), and insulin-like growth factor 1 (IGF1) as well as their receptors in rat brain regions after spontaneous morphine withdrawal in dependent animals. Morphine dependence in rats was induced within 6 days by 12 injections of morphine in increasing doses (10-100 mg/kg), and NO synthase inhibitor L-N(G)-nitroarginine methyl ester (L-NAME) (10 mg/kg) was given 1 h before each morphine injection. The expression of the BDNF, GDNF, NGF, IGF1, and their receptors in the frontal cortex, striatum, hippocampus, and midbrain was assessed 40 h after morphine withdrawal. L-NAME treatment during morphine intoxication resulted in an aggravation of the spontaneous morphine withdrawal severity. Morphine withdrawal was accompanied by upregulation of BDNF, IGF1, and their receptors TrkB and IGF1R, respectively, on the mRNA level in the frontal cortex, and only BDNF in hippocampus and midbrain. L-NAME administration during morphine intoxication decreased abstinence-induced upregulation of these mRNAs in the frontal cortex, hippocampus and midbrain. L-NAME prevented from abstinence-induced elevation of mature but not pro-form of BDNF polypeptide in the frontal cortex. While morphine abstinence did not affect TrkB protein levels as well as its phosphorylation status, inhibition of NO synthesis decreased levels of phosphorylated TrkB after withdrawal. Thus, NO signaling during induction of dependence may be involved in the mechanisms of BDNF expression and processing at abstinence, thereby affecting signaling through TrkB in the frontal cortex.

Elevation of BDNF exon I-specific transcripts in the frontal cortex and midbrain of rat during spontaneous morphine withdrawal is accompanied by enhanced pCreb1 occupancy at the corresponding promoter.

Brain-derived neurotrophic factor (BDNF) is believed to play a crucial role in the mechanisms underlying opiate dependence; however, little is known about specific features and mechanisms regulating its expression in the brain under these conditions. The aim of this study was to investigate the effects of acute morphine intoxication and withdrawal from chronic intoxication on expression of BDNF exon I-, II-, IV-, VI- and IX-containing transcripts in the rat frontal cortex and midbrain. We also have studied whether alterations of BDNF exon-specific transcripts are accompanied by changes in association of well-known transcriptional regulators of BDNF gene-phosphorylated (active form) cAMP response element binding protein (pCreb1) and methyl-CpG binding protein 2 (MeCP2) with corresponding regulatory regions of the BDNF gene. Acute morphine intoxication did not affect levels of BDNF exons in brain regions, while spontaneous morphine withdrawal in dependent rats was accompanied by an elevation of the BDNF exon I-containing mRNAs both in the frontal cortex and midbrain. During spontaneous morphine withdrawal, increased associations of pCreb1 were found with promoter of exon I in the frontal cortex and promoters of exon I, IV and VI in the midbrain. The association of MeCP2 with BDNF promoters during spontaneous morphine withdrawal did not change. Thus, BDNF exon-specific transcripts are differentially expressed in brain regions during spontaneous morphine withdrawal in dependent rats and pCreb1 may be at least partially responsible for these alterations.