Anaerobic Dechlorination

The observation that PCB contaminated sediments display a higher content of low chlorinated congeners than the mixture at the origin of the contamination was the first clue that anaerobic bacteria are able to degrade PCBs by a reductive dechlorination process. This process has been well documented for several aquatic sediments 30, 31, 32 . Anaerobic enrichment cultures able to dechlorinate PCBs were maintained in laboratory conditions, with and without sediment 33, 34, 35, 36, 37 . The...

Cdna Libraries

Numerous enzyme sequences have been identified in Arabidopsis, but little headway has been made in matching specific enzymes with their function on herbicide substrates. Molecular information on enzymes and function identification towards herbicides has been studied based on cDNA libraries. cDNA libraries are prepared from the mRNA of interest that is synthesized to DNA (cDNA) strand, which contains a specific coding region of a genome that is inserted into vectors and cloned 30 . Studies on...

Containing Gene Flow

Several molecular mechanisms have been suggested for containing gene flow (i.e., to prevent gene flow between the phytoremediating species and relatives), especially by pollen, ignoring the other routes of sporophyte propagule (seeds and asexual parts) movement, especially transgenes within the phytoremediating species (i.e., to prevent outflow to related species), or to mitigate the effects of transgene flow once it has occurred 20, 22, 26, 29 . It is more important to prevent gene flow from...

Decision Trees For Assessing The Level Of Risk

Here we combine the different factors through the use of decision trees. We want to state clearly that a decision tree is not a quantitative tool producing a quantified risk. It is an aid in risk evaluation providing unbiased guidance in indicating hazards attached to a certain species. When a hazard is indicated, more detailed and quantified data acquisition will often be necessary. Different levels of certainty apply to the various factors used. For instance invasiveness is highly...

Field scale contaminant fate and hydraulic control

Full-scale phytoremediation of VOCs has been active at contaminated sites since 1995 and 1996. In the decade since then, findings at the field sites have varied. In part the results are sketchy as some processes that are important were not previously considered and data collection is limited and largely unpublished. The full-scale phytoremediation site at the APG J-field site in Maryland is among the best characterized and analysed. Sampling at the site provided some of the first clear...

Forensic Field Studies

While conventional wisdom may dictate a progression from bench to greenhouse to field-testing of remedial technologies, there are distinct advantages to starting directly in the field to examine the rhizoremediation capabilities of natural vegetation. This approach affords a view of the long-term impacts of a diverse array of plant species, including mature trees, on microbial communities and or contaminant disappearance otherwise inaccessible due to the practical time limitations of most...

Info

In vitro culture and micropropagation Developing cell culture and micropropagation protocols for a diverse group of wetland monocot species was facilitated by the availability of a universal cell culture initiation medium, which had successfully been used for a great number of species 8, 10, 15 . The method comprised using immature inflorescences as explants and cultivating the tissue on a primary medium to produce totipotent embryogenic tissue culture, cultivating the embryogenic tissue on a...

Metabolism And Genetic Engineering Studies For Herbicide Phytoremediation

SCHNOOR2 biochemistry and Cell Biology, Rice University, Houston, Texas, USA 2Civil and Environmental Engineering, University of Iowa, Iowa City, IA, 52242, USA - Fax 01 319 3355660 E-mail jerald-schnoor uiowa.edu Herbicides are extensively used for the purpose of crop cultivation and still remain as an important strategy for the commercial agriculture. However, the widespread use of herbicides has resulted in both point source and non-point source...

Phytoremediation

Phytoremediation or the use of vegetation at waste sites or contaminated soils can overcome limitations of microbial cleanup such as low bacterial population or inadequate microbial activity. Improving the quality of surface water and reducing nonpoint source pollution can be achieved using wetland vegetation or vegetative filter strips to reduce herbicide runoff. Plants can remediate environments contaminated with organic compounds directly via root uptake, detoxification by...

Removal Of Pollutants Via Plants

Phytoextraction refers to the removal of pollutants from soils or water through plant uptake 66 . In this approach, the pollutants are not simply recycled back into the wetland, as is the case in phytostabilisation, but they are removed from the system by harvesting the plants or by volatilisation through the plants. The latter only applies to substances that can form gaseous compounds, such as Se 22, 67 and Hg 28 . For phytoextraction through uptake and harvest to be effective, uptake by the...

Tnt

Plants lack the excretion system of animals. In plant cells toxic metabolites and pollutants are sequestered into the vacuole. This Phase III type process is an active one and is catalyzed by membrane-bound ATP-driven pumps. A recent study indicated the existence of a Phase III system in poplar 36 . 4. Detoxification of the active oxygen species generated by the pollutant in trees Activated oxygen species (hydrogen peroxide, superoxide anion, and hydroxyl radical) are produced at various...

Preventing Establishment By Transgenic Mitigation

If a transgene confers even a small fitness disadvantage, the less fit transgenic volunteers and their own or hybrid progeny should only be able to exist as a very small proportion of the population. Therefore, it should be possible to mitigate volunteer establishment and gene flow by lowering the fitness of transgene recipients below the fitness of competitors, so that the volunteer or hybrid offspring will reproduce with considerably less success than its non-transgenic competitors. A concept...

Abc

Structure similarity between (A) Lignin monomer structure, where (1) X Y H (p-coumaryl alcohol), (2) X OMe Y H (coniferyl alcohol), (3) X Y OMe (sinapyl alcohol) 29 (B) 2,4-dichlorobiphenyl, PCB congener and (C) 2-4-dichlorophenoxyacetate. Among the first studies that specifically investigated the link between plant-derived chemicals and pollutant remediation was that by Donnelly et al., The authors demonstrated that a range of flavonoids could support the growth of PCB-degrading...

Days

Time course experiment of lindane disappearance in solution with chilli and coriander. Controls (white columns), chilli (black columns), coriander (grey columns). Data points represent the means of 5 replicates determinations. Bar SD. the effect of the rhizosphere on these compounds. Five plant species were harvested and separated into roots, stems and leaves Chenopodium vulgare, Solanum nigrum, Cytisus striatus, Vicia sativa and Avena sativa. Concentrations of total HCH in plant...

Oxygen Release By Roots Into Rhizosphere Of Helophytes

Oxygen reaching the root aerenchyma is respired by the root tissues and diffuses towards to the root apex and radially to the rhizosphere, to be consumed in the surrounding soil 54 . The oxygen flux from the root aerenchyma to the rhizosphere, known as radial oxygen loss (ROL), is determined by the concentration gradient, the consumption of oxygen by the cells along the radial path, and the physical resistance to oxygen diffusion 54, 56 . As a result, 30-40 of the oxygen supplied via the...

Rhizosphere Ecology

Yu et al., reported the recovery, by three to four orders of magnitude, of more resin acid degraders (tricyclic terpenoids originating from softwood trees) in hydrocarbon-contaminated soils than in pristine Arctic tundra soil 60 . Notably, the soil samples were collected thousands of kilometres from the nearest source of resin acids (conifer forest) and contained no native resin acids. The bacteria isolated in the study, Pseudomonas and Sphingomonas, are hydrocarbons degraders, which suggested...

Sage

Serial analysis of gene expression (SAGE) is a method that allows the quantitative and simultaneous analysis of a large number of transcripts 42 . The first application of this technique in higher plants was used for profiling expressed genes in rice (Oryza sativa L.) seedlings 43 . Recent applications of SAGE technique in plants consist of wood formation in loblolly pine 44 gene expression pattern in the crop plant cassava (Manihot esculenta) from viral disease resistance and susceptible...