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PubMed2004

Free radicals and antioxidants in human health: current status and future prospects.

Free radicals and related species have attracted a great deal of attention in recent years. They are mainly derived from oxygen (reactive oxygen species/ROS) and nitrogen (reactive nitrogen species/RNS), and are generated in our body by various endogenous systems, exposure to different physicochemical conditions or pathophysiological states. Free radicals can adversely alter lipids, proteins and DNA and have been implicated in aging and a number of human diseases. Lipids are highly prone to free radical damage resulting in lipid peroxidation that can lead to adverse alterations. Free radical damage to protein can result in loss of enzyme activity. Damage caused to DNA, can result in mutagenesis and carcinogenesis. Redox signaling is a major area of free radical research that is attracting attention. Nature has endowed us with protective antioxidant mechanisms- superoxide dismutase (SOD), catalase, glutathione, glutathione peroxidases and reductase, vitamin E (tocopherols and tocotrienols), vitamin C etc., apart from many dietary components. There are epidemiological evidences correlating higher intake of components/ foods with antioxidant abilities to lower incidence of various human morbidities or mortalities. Current research reveals the different potential applications of antioxidant/free radical manipulations in prevention or control of disease. Natural products from dietary components such as Indian spices and medicinal plants are known to possess antioxidant activity. Newer and future approaches include gene therapy to produce more antioxidants in the body, genetically engineered plant products with higher level of antioxidants, synthetic antioxidant enzymes (SOD mimics), novel biomolecules and the use of functional foods enriched with antioxidants.

Antioxidants↗
PubMed1990

[Analysis of the incidence of vibration disease in machine-building industry].

A study was performed of vibration disease prevalence and morbidity dynamics for 10 years at the enterprises of the RSFSR Ministry of Machine-Building Industry. The results of the study proved that the major VD prevalence was found in automobile, heavy and energy machinery industries, machine-tool and agriculture machinery industry (80%). With regard to the morbidity rate and duration of work/D morbidity correlation, the contributors identified 8 major VD-risk professions, including those for female workers, an earlier development of the disease being more characteristic of females in some professional groups. It was established that some are less/or more liable to VD in comparison with others of the same professional group, which can be accounted for by different individual factors that influence the latent development of the disease. The revealed differences can determine the most promising techniques in VD prevention at machine-engineering plants.

Adult↗
PubMed2003

Comparison of two atmospheric-dispersion models to assess farm-site exposure to sour-gas processing-plant emissions.

We describe two approaches for exposure assessment that we used in a large-scale retrospective cattle study conducted in Alberta, Canada. Sulfur dioxide (SO(2)) was the surrogate measure of exposure to a complex mixture of combusted sour-gas emissions. Monthly air pollution dispersion modeling (1985-1994) (based on individual industrial source processing-plant engineering specifications, emission volumes, and meteorologic information) provided exposure isopleths of sulfur dioxide concentration from each of 231 sour-gas processing-plants across the province. In contrast, a simpler measure of proximity to source(s) of varying emission rates was applied in a geographical information system based on simplified pollution decay at increasing distances from each point source. Province-wide (663,000 km(2)) surface analysis (by exposure-level classification) produced a contingency coefficient of 0.68 between the two exposure estimates. Annual exposure estimates at the 1382 dairy and 5726 beef cow-calf farms studied were highly correlated over the 10-years period (r(spearman)=0.82 and 0.83, respectively), while monthly exposure estimates were somewhat less correlated (r(spearman)=0.80 and 0.82, respectively) for the two exposure assessment methods. Crude exposure estimates from each method were similar in both direction and magnitude.

Agriculture↗
PubMed2001

Plants as ecosystem engineers in subsurface-flow treatment wetlands.

Mass balance performance data from side by side studies of planted and unplanted gravel-bed treatment wetlands with horizontal subsurface-flow are compared. Planted systems showed enhanced nitrogen and initial phosphorus removal, but only small improvements in disinfection, BOD, COD and suspended solids removal. Direct nutrient uptake by plants was insufficient to account for more than a fraction of the improved removal shown by planted systems. Roles of plants as ecosystem engineers are summarised, with organic matter production and root-zone oxygen release identified as key factors influencing nutrient transformation and sequestration.

Biodegradation, Environmental↗
PubMed1994

Modification of lignin biosynthesis in transgenic Nicotiana through expression of an antisense O-methyltransferase gene from Populus.

An aspen lignin-specific O-methyltransferase (bi-OMT; S-adenosyl-L-methionine: caffeic acid/5-hydroxyferulic acid 3/5-O-methyltransferase, EC 2.1.1.68) antisense sequence in the form of a synthetic gene containing the cauliflower mosaic virus 35S gene sequences for enhancer elements, promoter and terminator was stably integrated into the tobacco genome and inherited in transgenic plants with a normal phenotype. Leaves and stems of the transgenes expressed the antisense RNA and the endogenous tobacco bi-OMT mRNA was suppressed in the stems. Bi-OMT activity of stems was decreased by an average of 29% in the four transgenic plants analyzed. Chemical analysis of woody tissue of stems for lignin building units indicated a reduced content of syringyl units in most of the transgenic plants, which corresponds well with the reduced activity of bi-OMT. Transgenic plants with a suppressed level of syringyl units and a level of guaiacyl units similar to control plants were presumed to have lignins of distinctly different structure than control plants. We concluded that regulation of the level of bi-OMT expression by an antisense mechanism could be a useful tool for genetically engineering plants with modified lignin without altering normal growth and development.

Base Sequence↗
PubMed2006

Fees or refuges: which is better for the sustainable management of insect resistance to transgenic Bt corn?

The evolution of resistance in insect pests will imperil the efficiency of transgenic insect-resistant crops. The currently advised strategy to delay resistance evolution is to plant non-toxic crops (refuges) in close proximity to plants engineered to express the toxic protein of the bacterium Bacillus thuringiensis (Bt). We seek answers to the question of how to induce growers to plant non-toxic crops. A first strategy, applied in the United States, is to require Bt growers to plant non-Bt refuges and control their compliance with requirements. We suggest that an alternative strategy is to make Bt seed more expensive by instituting a user fee, and we compare both strategies by integrating economic processes into a spatially explicit, population genetics model. Our results indicate that although both strategies may allow the sustainable management of the common pool of Bt-susceptibility alleles in pest populations, for the European corn borer (Ostrinia nubilalis) one of the most serious pests in the US corn belt, the fee strategy is less efficient than refuge requirements.

Animals↗
PubMed1996

Exposures and health effects: an evaluation of workers at a sodium azide production plant.

Sodium azide is the principal gas-generating agent used to inflate automobile supplemental restraint systems, more commonly called airbags. Although sodium azide is known to affect the cardiovascular system by causing peripheral vasodilation, there is no published literature describing occupational exposures to sodium azide in the rapidly growing automobile airbag industry. In 1994-1995, the National Institute for Occupational Safety and Health (NIOSH) conducted a cross-sectional study of health complaints reported by sodium azide production workers at the only continuous sodium azide production facility in the United States. The NIOSH evaluation consisted of a plant industrial hygiene survey, a symptom questionnaire, ambulatory blood pressure monitoring, and blood azide analysis. Personal breathing zone air monitoring revealed exposures to sodium azide and hydrazoic acid (a reactant product) at levels greater than the NIOSH Recommended Exposure Limits (RELs). In some cases, exposures exceeded the REL despite the use of air-supplied respirators. The questionnaire revealed that most workers reported headache (10 of 11 [91%]), episodes of low blood pressure (9 of 11 [82%]), and palpitations (8 of 11 [73%]) occurring in the production areas within the 6 months preceding the study. Mild headache (4 of 11 [36%]) was the only symptom reported during our 24-hr medical survey. Ambulatory blood pressure monitoring revealed one asymptomatic employee with a drop in blood pressure (defined as a drop in systolic [at least 20 mm Hg] and diastolic [at least 10 mm Hg] blood pressure) during a period of exposure to sodium azide at a level five times the NIOSH REL. Improvements in plant engineering controls, increased attention to employee hygiene practices, and a more comprehensive respiratory protection program were recommendations made by NIOSH to reduce exposures at the plant. All facilities handling sodium azide should be aware of the potential toxicity of sodium azide and hydrazoic acid.

Adult↗
PubMed1999

No induction of beta-oxidation in leaves of Arabidopsis that over-produce lauric acid.

Leaves from transgenic Brassica napus L. plants engineered to produce lauric acid show increased levels of enzyme activities of the pathways associated with fatty acid catabolism (V.A. Eccleston and J.B. Ohlrogge, 1998, Plant Cell 10: 613-621). In order to determine if the increases in enzyme activity are mirrored by increases in the expression of genes encoding enzymes of beta-oxidation, which is the major pathway of fatty acid catabolism in plants, the medium-chain acyl-acyl carrier protein (ACP) thioesterase MCTE from California bay (Umbellularia california) was over-expressed under the control of the cauliflower mosaic virus 35S promoter in Arabidopsis thaliana (L.) Heynh. Arabidopsis was the most suitable choice for these studies since gene expression could be analyzed in a large number of independent MCTE-expressing lines using already well-characterized beta-oxidation genes. Levels of MCTE transcripts in leaves varied widely over the population of plants analyzed. Furthermore, active MCTE was produced as determined by enzymatic analysis of leaf extracts of MCTE-expressing plants. These plants incorporated laurate into triacylglycerol of seeds, but not into lipids of leaves as shown by gaschromatographic analysis of total fatty acid extracts. The expression levels of the beta-oxidation and other genes that are highly expressed during developmental stages involving rapid fatty acid degradation were measured. No significant difference in gene expression was observed among MCTE-expressing plants and transgenic and non-transgenic controls. To eliminate the possibility that post-translational mechanisms are responsible for the observed increases in enzyme activity acyl-CoA oxidase activity was also measured in leaves of MCTE-expressing plants using medium and long chain acyl-CoA substrates. No significant increases in either medium- or long-chain acyl-CoA oxidase activities were detected. We conclude that endogenous beta-oxidation is sufficient to account for the complete degradation of laurate produced in rosette leaves of Arabidopsis expressing MCTE.

Acyl-CoA Oxidase↗
PubMed2001

Ectopic expression of ABI3 gene enhances freezing tolerance in response to abscisic acid and low temperature in Arabidopsis thaliana.

The plant hormone abscisic acid (ABA) regulates several physiological and developmental processes in plants, including stress adaptation and seed maturation. ABA-mediated processes appear to be central in plant cold acclimation and expression of cold acclimation-related genes. Ectopic expression of ABI3 encoding a seed-specific transcriptional activator confers on Arabidopsis vegetative tissues the ability to accumulate seed-specific transcripts in response to ABA, and also influences some ABA-mediated vegetative responses. In the present study we characterized the effect of ectopic expression of ABI3 on cold acclimation and development of freezing tolerance in Arabidopsis. We first determined the effect of ABI3 on ABA-induced expression of cold acclimation-related genes. Expression of ABI3 increased the ABA-induced accumulation of transcripts for several ABA/cold/drought-responsive genes such as RAB18 and LTI78. Enhanced expression of these genes was evident even after transient application of ABA, and the enhanced expression was correlated with increased freezing tolerance in ABI3 transgenic plants. Ectopic expression of ABI3 also appeared to modulate low temperature-induced freezing tolerance. The ABI3 transgenic plants acclimated faster than the wild-type plants, and the maximum tolerance obtained was significantly higher. These data showed that lower levels of ABA were needed to trigger the expression of the genes and to maintain the freezing-tolerant state in the ABI3 transgenic plants, and indicate that ectopic expression of ABI3 leads to enhanced responsiveness to ABA. The ectopic expression of ABI3 could provide a new strategy for engineering plant stress tolerance.

Abscisic Acid↗
PubMed2002

Overexpression of a 9-cis-epoxycarotenoid dioxygenase gene in Nicotiana plumbaginifolia increases abscisic acid and phaseic acid levels and enhances drought tolerance.

The plant hormone abscisic acid (ABA) plays important roles in seed maturation and dormancy and in adaptation to a variety of environmental stresses. An effort to engineer plants with elevated ABA levels and subsequent stress tolerance is focused on the genetic manipulation of the cleavage reaction. It has been shown in bean (Phaseolus vulgaris) that the gene encoding the cleavage enzyme (PvNCED1) is up-regulated by water stress, preceding accumulation of ABA. Transgenic wild tobacco (Nicotiana plumbaginifolia Viv.) plants were produced that overexpress the PvNCED1 gene either constitutively or in an inducible manner. The constitutive expression of PvNCED1 resulted in an increase in ABA and its catabolite, phaseic acid (PA). When the PvNCED1 gene was driven by the dexamethasone (DEX)-inducible promoter, a transient induction of PvNCED1 message and accumulation of ABA and PA were observed in different lines after application of DEX. Accumulation of ABA started to level off after 6 h, whereas the PA level continued to increase. In the presence of DEX, seeds from homozygous transgenic line TN1 showed a 4-d delay in germination. After spraying with DEX, the detached leaves from line TN1 had a drastic decrease in their water loss relative to control leaves. These plants also showed a marked increase in their tolerance to drought stress. These results indicate that it is possible to manipulate ABA levels in plants by overexpressing the key regulatory gene in ABA biosynthesis and that stress tolerance can be improved by increasing ABA levels.

Abscisic Acid↗
PubMed1979

Special project consultants can aid hospital engineers.

Hospital engineers occasionally need consultants to study overall operations, suggest improvements, and develop cost-cutting programs. Day-to-day operations often keep in-plant engineers too busy to undertake these kinds of special projects. But given the crucial need for hospitals to cut energy consumption and costs, these special studies need to be done. The right consultant can do the job.

Consultants↗
PubMed1995

Immunogenicity of transgenic plant-derived hepatitis B surface antigen.

The focus of the Children's Vaccine Initiative is to encourage the discovery of technology that will make vaccines more readily available to developing countries. Our strategy has been to genetically engineer plants so that they can be used as inexpensive alternatives to fermentation systems for production of subunit antigens. In this paper we report on the immunological response elicited in vivo by using recombinant hepatitis B surface antigen (rHBsAg) purified from transgenic tobacco leaves. The anti-hepatitis B response to the tobacco-derived rHBsAg was qualitatively similar to that obtained by immunizing mice with yeast-derived rHBsAg (commercial vaccine). Additionally, T cells obtained from mice primed with the tobacco-derived rHBsAg could be stimulated in vitro by the tobacco-derived rHBsAg, yeast-derived rHBsAg, and by a synthetic peptide that represents part of the a determinant located in the S region (139-147) of HBsAg. Further support for the integrity of the T-cell epitope of the tobacco-derived rHBsAg was obtained by testing the ability of the primed T cells to proliferate in vitro after stimulation with a monoclonal anti-idiotype and an anti-idiotype-derived peptide, both of which mimic the group-specific a determinant of HBsAg. In total, we have conclusively demonstrated that both B- and T-cell epitopes of HBsAg are preserved when the antigen is expressed in a transgenic plant.

Amino Acid Sequence↗
PubMed2003

Rhizosecretion of recombinant proteins from plant hairy roots.

Rhizosecretion of a target protein in the hydroponic medium provides an alternative manufacturing platform that simplifies the downstream purification procedure and increases protein yield. In order to increase the production rates of rhizosecreted proteins, we have exploited the ability of Agrobacterium rhizogenes to induce the formation of large amounts of root tissue on transgenic tobacco plants engineered to secrete a model recombinant protein, human secreted alkaline phosphatase (SEAP). The secretion of SEAP from hairy roots induced on the stems of transgenic tobacco plants was 5-7 times higher than that from adventitious transgenic roots.

Alkaline Phosphatase↗
PubMed1999

The chloroplast small heat shock protein undergoes oxidation-dependent conformational changes and may protect plants from oxidative stress.

The nuclear-encoded chloroplast-localized Hsp21 is an oligomeric heat shock protein (Hsp), belonging to the protein family of small Hsps and alpha-crystallins. We have investigated the effects of high temperature and oxidation treatments on the structural properties of Hsp21, both in purified recombinant form and in transgenic Arabidopsis thaliana plants engineered to constitutively overexpress Hsp21. A conformational change was observed for the 300 kDa oligomeric Hsp21 protein during moderate heat stress (< or =40 degrees C) of Arabidopsis plants, as judged by a shift to lower mobility in non-denaturing electrophoresis. Similar changes in mobility were observed when purified recombinant Hsp21 protein was subjected to an oxidant. Exposure of Hsp21 protein to temperatures above 70 degrees C led to irreversible aggregation, which was prevented in presence of the reductant dithiothreitol. The transgenic plants that constitutively overexpressed Hsp21 were more resistant to heat stress than were wildtype plants when the heat stress was imposed under high light conditions. These results suggest that the physiological role of Hsp21 involves a response to temperature-dependent oxidative stress.

Arabidopsis↗
PubMed1996

Manipulation of glutathione metabolism in transgenic plants.

There is clear potential for the genetic manipulation of key enzymes involved in stress metabolism in transgenic plants. However, the data emerging so far from such experiments are equivocal. The detailed analysis of stress responses in progeny of primary transgenics, coupled with comparisons with control transgenic plants that do not contain the GR transgene, allows us to take into account the possible variation in response to stress associated with regeneration of plants from tissue culture. The picture that is now beginning to emerge with respect to the role of GR in stress protection is that, although there are clearly benefits to be had from overexpression of the enzymes, there is no direct correlation between enzyme levels and stress tolerance. It may be that overexpression of the cytosolic isoform (gor2) will prove to be of greater benefit. Furthermore, the types of stresses to which transgenic plants have been exposed in order to assess the consequences of oxidative stress tolerance cannot reproduce those that will experienced in field conditions. Only when plants with higher GR levels and increased glutathione synthesis capacity are grown in field trials will it be possible to make a full assessment of the benefits of engineering plants with altered glutathione metabolism.

Amino Acid Sequence↗
PubMed2003

Metabolite profiling as a functional genomics tool.

Plants accumulate a very large number of small molecules (phytochemicals) with important functions in the ecology of plants and in the protection against biotic and abiotic stress conditions. Little is known on how phytochemical biosynthetic pathways are regulated, which is a key step to successfully engineering plant metabolism. Plant natural products are usually not essential, and genetic analyses often fail to identify phenotypes associated with the absence of these compounds. We have investigated the use of metabolite profiling of plant cells in culture to establish the function of transcription factors suspected to control plant metabolic pathways.

Cell Culture Techniques↗
PubMed1994

Streamlining environmental safety in the operating room: a common bond between surgeons and hospital engineers.

The operating room presents environmental safety concerns unlike any problems in other parts of a health care facility. Special disciplines must be utilized to ensure that risk is minimized during surgery. This document addresses the needs of both the surgeon and the plant engineer in order for both groups to learn more about the other's concerns and problems.

Electric Wiring↗
PubMed1995

The use of digoxigenin-labelled probes to detect DNA sequences specific for plant pathogenic bacteria.

Southern blot hybridization is a valuable method in the assessment of the pathogenicity of bacterial strains or isolates. It is also a powerful tool for the demonstration of the presence of foreign DNA sequences in the genome of genetically-engineered plant cells. In this respect, cold, digoxigenin-labelled DNA probes can be used in place of classical radioactive probes, whether hybridizations are performed on bacterial genomic or plasmidic DNA, or on plant genomic DNA. The versatility of this cold labelling makes it suitable for the detection of unique bacterial genomic or plasmid sequences, even though these are located on large plasmids. The sensitivity of this cold probe technique also permits the detection of subpicogram quantities of DNA in plant genomic preparations. Their long term storage stability allows them to be frequently re-used over long periods of time, making this technique quite cost efficient.

Bacteria↗