Edible Plant Material Research Articles

Arsenic contamination of soils and agricultural plants through irrigation water in Nepal

This study monitored the influence of arsenic-contaminated irrigation water on alkaline soils and arsenic uptake in agricultural plants at field level. The arsenic concentrations in irrigation water ranges from <0.005 to 1.014 mg L(-1) where the arsenic concentrations in the soils were measured from 6.1 to 16.7 mg As kg(-1). The arsenic content in different parts of plants are found in the order of roots>shoots>leaves>edible parts. The mean arsenic content of edible plant material (dry weight) were found in the order of onion leaves (0.55 mg As kg(-1))>onion bulb (0.45 mg As kg(-1))>cauliflower (0.33 mg As kg(-1))>rice (0.18 mg As kg(-1))>brinjal (0.09 mg As kg(-1))>potato (<0.01 mg As kg(-1)).

Microbial functions in space: Mars transit to early planetary base exploration missions

Microbial processing of liquid and solid wastes may play a role in the advanced life support systems of nearer term human exploration missions such as transit vehicles to Mars or initial surface bases on either the Moon or Mars. Recycling wastewater (urine, atmospheric condensate, hygiene water) is a critical component of reducing storage and resupply requirements on such missions, and microbial treatment of all or part of the waste stream may improve overall treatment efficiency. As small-scale plant systems (i.e., 5– 10 m 2 person - 1 ) are used to supplement food storage, microbial processing of both wastewater and edible plant material will facilitate nutrient and water recycling through the biomass production systems.

Mucosal immunization using recombinant plant-based oral vaccines

The induction of mucosal immunity is very important in conferring protection against pathogens that typically invade via mucosal surfaces. Delivery of a vaccine to a mucosal surface optimizes the induction of mucosal immunity. The apparent linked nature of the mucosal immune system allows delivery to any mucosal surface to potentially induce immunity at others. Oral administration is a very straightforward and inexpensive approach to deliver a vaccine to the mucosal lining of the gut. However, vaccines administered by this route are subject to proteolysis in the gastrointestinal tract. Thus, dose levels for protein subunit vaccines are likely to be very high and the antigen may need to be protected from proteolysis for oral delivery to be efficacious. Expression of candidate vaccine antigens in edible recombinant plant material offers an inexpensive means to deliver large doses of vaccines in encapsulated forms. Certain plant tissues can also stably store antigens for extensive periods of time at ambient temperatures, obviating the need for a cold-chain during vaccine storage and distribution, and so further limiting costs. Antigens can be expressed from transgenes stably incorporated into a host plant’s nuclear or plastid genome, or from engineered plant viruses infected into plant tissues. Molecular approaches can serve to boost expression levels and target the expressed protein for appropriate post-translational modification. There is a wide range of options for processing plant tissues to allow for oral delivery of a palatable product. Alternatively, the expressed antigen can be enriched or purified prior to formulation in a tablet or capsule for oral delivery. Fusions to carrier molecules can stabilize the expressed antigen, aid in antigen enrichment or purification strategies, and facilitate delivery to effector sites in the gastrointestinal tract. Many antigens have been expressed in plants. In a few cases, vaccine candidates have entered into early phase clinical trials, and in the case of farmed animal vaccines into relevant animal trials.

Oral hepatitis B vaccine candidates produced and delivered in plant material

Hepatitis B is a major global health problem; approximately two billion people are infected with the virus worldwide, despite the fact that safe and efficacious vaccines have been developed and used for nearly 20 years. Prohibitive costs for vaccine purchase and administration restrict uptake in many developing nations. Agencies such as the Global Alliance for Vaccination and Immunization are helping to make current vaccines more available, but reduced costs would greatly aid this effort. Oral delivery is an option to reduce the expense of administering hepatitis B vaccines. It may also improve compliance, and orally delivered vaccines may be more efficacious among poor responders to current vaccines. However, to induce protective efficacy, oral administration may require encapsulation of antigen and delivery of large doses. Plant-based expression systems offer an oral delivery alternative with low production costs, and they also encapsulate the antigen. Some plant-based systems also stabilize antigen and therefore reduce storage and distribution costs. The hepatitis B major surface antigen has been expressed in several plant systems. A variety of regulatory sequences and subcellular targets have been used to achieve expression suitable for early stage clinical trials. However, further increase in expression will be necessary for practical and efficacious products. Appropriate processing can yield palatable products with uniform antigen concentration. The antigen expressed in plant systems shows extensive disulphide cross-linking and oligomerization and forms virus-like particles. Oral delivery of the antigen in plant material can induce a serum antibody response, prime the immune system for a subsequent injection of antigen and give a boosted response to a prior injection. Small scale clinical trials in which the antigen has been delivered orally in edible plant material indicate safety and immunogenicity.

Plant-based immunocontraceptive control of wildlife—“potentials, limitations, and possums”

Possums ( Trichosurus vulpecula), originally introduced from Australia, are spread over 90% of New Zealand and cause major economic and environmental damage. Immunocontraception has been suggested as a humane means to control them. Marsupial-specific reproductive antigens expressed at high levels in edible transgenic plant tissue might provide a safe, effective, and cheap oral delivery bait for immunocontraceptive control. As proof of concept, female possums vaccinated with immunocontraceptive antigens showed reduced fertility, and possums fed with potato-expressed heat labile toxin-B (LT-B) had mucosal and systemic immune responses to the antigen. This demonstrated that immunocontraception was effective in possums and that oral delivery in edible plant material might be possible. Nuclear transformation with reporter genes showed that transgenic carrot roots accumulate high levels of foreign protein in edible tissues, indicating their potential as a delivery vector. However, prior to attempts at large scale production, more effective immunocontraceptive antigen-adjuvant formulations are probably required before plant-based immunocontraception can become a major tool for immunocontraceptive control of overabundant vertebrate pests.

Variation within and between two saltbush species in plant composition and subsequent selection by sheep

This work examines nutritive value and preference by sheep of 2 saltbush species, river saltbush (Atriplex amnicola) and old man saltbush (Atriplex nummularia). Both species are woody perennials that are native to Australia and used in commercial grazing systems. The hypothesis for this study was that sheep will graze saltbushes with higher nutritive value and lower secondary compounds in preference to bushes with lower nutritive value and higher secondary compounds. This was expected to be found both within and between the old man and river saltbush species. To test the hypothesis, 10-month-old Merino ewes grazed a 10-ha plot containing a mixture of old man and river saltbush in approximately equal proportions. Within the plot, and prior to grazing, 20 bushes of each species were pegged for identification and samples of edible plant material collected for analysis. Each week during the grazing period the bushes were photographed for assessment of preference. Sheep preferred river saltbush to old man saltbush and also showed some preferences for specific bushes within each species. Differences in digestibility of dry matter and organic matter, crude protein, ash, oxalates, and nitrates were not clearly associated with differences in preference. Although the reasons for preferences were not demonstrated, the analysis of the plant material did indicate that the content of total ash and oxalates was at levels likely to depress voluntary feed intake.

Advantageous Features of Plant-based Systems for the Development of HIV Vaccines

Plants have recently become an attractive option for the production of recombinant proteins. Plant-based systems can be used to produce many classes of foreign proteins including candidate vaccine antigens. The selected antigen can be purified from plant material prior to delivery by the preferred route, or alternatively delivered orally in edible plant material that has been processed to give a homogeneous and stable product. Several plant species have been used to express a wide range of vaccine candidates with tobacco, potato and corn being particularly favored. Corn seed is especially well suited to various food processing technologies that generate dry homogeneous material suitable for extended storage and refrigeration-free transport and distribution. Many antigens have been expressed in corn and assessed for efficacy in trials with generally positive results. Candidate HIV vaccines are particularly good targets for plant-based oral delivery since there is a great need for an easily distributed affordable vaccine that could be administered without injection and induce strong mucosal immune responses. As a first step in evaluating plant expression technology with a relevant antigen that might easily be tested in an animal system, we expressed the SIV major surface glycoprotein gp130 (analogous to HIV gp120) in corn seed. Expression levels were achieved that are compatible with conducting oral delivery trials in animals.

Cell wall hydroxycinnamates in wild rice ( Zizania aquatica L.) insoluble dietary fibre

The contents of ester-linked phenolic acids in wild rice (Zizania aquatica L.) dietary fibre were quantified by HPLC analysis, and oligosaccharide hydroxycinnamates were isolated and identified to investigate the linkages of hydroxycinnamic acids to cell wall polymers. In wild rice insoluble dietary fibre (WRIDF), ferulic acid was the most abundant phenolic acid (3942 µg g–1), but significant amounts of sinapic acid (518 µg g–1) and p-coumaric acid (142 µg g–1) were also detected. Treatment of WRIDF with carbohydrate hydrolases or trifluoroacetic acid released several oligosaccharide hydroxycinnamates. After fractionation with Amberlite XAD-2, five feruloylated oligosaccharides were isolated by gel chromatography and semi-preparative HPLC and identified as arabinoxylan ferulate fragments. The feruloylated tetrasaccharide {[5-O-(trans-feruloyl)][O-β-D-Xylp-(1→2)]-O-α-L-Araf-(1→3)}-O-β-D-Xylp-(1→4)-D-Xylp was isolated for the first time from edible plant material. Although some results indicated that sinapic acid is also (at least partially) linked through an ester bond to polysaccharides, isolation of defined oligosaccharide sinapates was not achieved.

Factors important in the extraction, stability and in vitro assembly of the hepatitis B surface antigen derived from recombinant plant systems.

The expression of vaccine antigens in edible plant material together with their delivery by the oral route constitutes a powerful paradigm, with the potential to dramatically reduce the cost of vaccine production and administration, in addition to improving distribution and patient compliance. These products will be subject to many of the same regulations applied to current injectable vaccines, so reliable methods to quantify antigen and ensure stability in crude plant extracts are required. As a model system the hepatitis B surface antigen (HBsAg) was expressed in soybean and tobacco cell cultures. This complex antigen consists of membrane-associated small surface antigen proteins (p24(s)), disulfide cross-linked to yield dimers and higher multimers. Although the total p24(s) extracted from plant cells was relatively unaffected by detergent concentration, the quantification of antigenically reactive product depended strongly on the ratio of detergent to cell concentration. Furthermore, 1-20% w/v sodium ascorbate improved the measured levels of monoclonal-reactive antigen 4- to 12-fold. Detergent also influenced antigen stability in cell lysates stored at 4 degrees C; under optimum conditions stability was maintained for at least 1 month, whereas excess detergent rendered the antigen susceptible to proteolytic degradation. This proteolysis could be counteracted by the addition of skim milk or its protein component, which stabilized antigenically reactive p24(s) for up to 2 months. The immunologically relevant epitopes of HBsAg are critically dependent on disulfide bonding. By altering the sodium ascorbate concentration or buffer pH the proportion of HBsAg displaying the monoclonal reactive epitopes was increased between 8- and 20-fold. In addition, under certain conditions the dimerized p24(s) could be converted to oligomeric aggregates, resembling the form of the serum-derived antigen. These simple in vitro manipulations, compatible with the goal of a minimally processed oral vaccine, may prove valuable in increasing the immunogenicity of the plant-derived antigen.

Antioxidant activity of plant extracts containing phenolic compounds.

The antioxidative activity of a total of 92 phenolic extracts from edible and nonedible plant materials (berries, fruits, vegetables, herbs, cereals, tree materials, plant sprouts, and seeds) was examined by autoxidation of methyl linoleate. The content of total phenolics in the extracts was determined spectrometrically according to the Folin-Ciocalteu procedure and calculated as gallic acid equivalents (GAE). Among edible plant materials, remarkable high antioxidant activity and high total phenolic content (GAE > 20 mg/g) were found in berries, especially aronia and crowberry. Apple extracts (two varieties) showed also strong antioxidant activity even though the total phenolic contents were low (GAE < 12.1 mg/g). Among nonedible plant materials, high activities were found in tree materials, especially in willow bark, spruce needles, pine bark and cork, and birch phloem, and in some medicinal plants including heather, bog-rosemary, willow herb, and meadowsweet. In addition, potato peel and beetroot peel extracts showed strong antioxidant effects. To utilize these significant sources of natural antioxidants, further characterization of the phenolic composition is needed.

Inhibitory effect of antibodies to synthetic sperm antigen(YAL-198) on development of embryo

Possums (Trichosurus vulpecula), originally introduced from Australia, are spread over 90% of New Zealand and cause major economic and environmental damage. Immunocontraception has been suggested as a humane means to control them. Marsupial-specific reproductive antigens expressed at high levels in edible transgenic plant tissue might provide a safe, effective, and cheap oral delivery bait for immunocontraceptive control. As proof of concept, female possums vaccinated with immunocontraceptive antigens showed reduced fertility, and possums fed with potato-expressed heat labile toxin-B (LT-B) had mucosal and systemic immune responses to the antigen. This demonstrated that immunocontraception was effective in possums and that oral delivery in edible plant material might be possible. Nuclear transformation with reporter genes showed that transgenic carrot roots accumulate high levels of foreign protein in edible tissues, indicating their potential as a delivery vector. However, prior to attempts at large scale production, more effective immunocontraceptive antigen-adjuvant formulations are probably required before plant-based immunocontraception can become a major tool for immunocontraceptive control of overabundant vertebrate pests.

STRUCTURAL AND CHEMICAL BASES FOR TEXTURE OF PLANT FOODSTUFFS

Following a brief review of plant morphology, tissue organization and cell structure, the structure/texture relationship in edible plant materials is discussed with special emphasis on the role of cell wall and cytoplasmic components (starch, protein, lipids and vacuolar solutes). The review of published experimental data is supplemented with information deducible from interfacing the disciplines of plant physiology/microscopy and food science/texture. Recent engineering studies on tissue failure are discussed and their relevance to the advancement of the structure/texture relationship is pointed out.

Trace elements in desert soils irrigated with Nile and wastewater

Abstract The present study was conducted to evaluate the status of trace elements (Cd, Cu, Fe, Mn, Ni, Pb, Zn) in soil and cultivated crops under a long‐term irrigation with wastewater and Nile water. The average concentrations of Cd, Cu, Fe, Mn, Ni, Pb, and Zn were 0.011, 0.42, 0.76, 0.34, 0.09, 0.21, and 0.31 μg mL−1 in waste‐water, and 0.008, 0.022, 0.27, 0.05, 0.01, 0.05, and 0.09 μ.g mL−1 in Nilewater, respectively. Soil irrigated with wastewater contained 0.23–1.00% Fe, 24–135 μ.g Cu g−1, 0.85–1.85 μg Cd g−1, 90–340 μg Mn g−1, 18–34 μg Ni g−1, 28–180 μg Pb g−1, and 86–615 μg Zn g−1. The highest values were always found in the surface layer (0–20 cm). Lower concentration of these trace elements were detected in soil irrigated with Nile water and also in uncultivated soil. The fractions of these elements extracted by ammonium acetate, DTPA, and ammonium oxalate were relatively higher in soil under irrigation with wastewater than in that irrigated with Nile water. Generally, the amounts of DTPA‐extractable Cd, Cu, Fe, Mn, Ni, Pb, and Zn in soil were below levels toxic to plants. The concentrations of trace elements in the tested fruits and juices of lemon and mandarin, bean seeds, and corn grain grown under continuous irrigation with wastewater were below the standard critical levels of edible plant materials recommended by the Food Standard Committee of United Kingdom.

Primate communities: Their structure and role in tropical ecosystems

The structure of primate communities living in a number of undisturbed areas is described and compared. Species richness is highest in tropical rain forests of Africa and South America, where up to 14 different species can share the same habitat. The number of sympatric primates in woodlands and savannas is always much lower. Some striking differences in community structure may be observed between communities living in apparently similar habitats. Three major factors may be held responsible for such discrepancies: history and paleoecology, present spatial heterogeneity of the vegetation, and competition with other taxonomic groups. The role of primates in the functioning of forest ecosystems is discussed. Though their trophic impact may be important, the role they play in seed dispersal appears to be more significant; they contribute greatly to homeostasis, as well as to regeneration, of the rain forests. A number of ecological traits are particularly developed among primates and may have contributed to the rapid evolutionary success of the order. Their predominantly vegetarian diet allows them to build up higher population densities than sympatric carnivorous mammals;their arborealism permits them to make use of all edible plant material available in a tridimensional environment; the opportunistic tendencies of some cebids, cercopithecids, and pongids enable them to take advantage of a variety of habitats and situations; and finally, an extended socialization period and a long life-span, allowing them to develop social traditions, give to many of them a further possibility to adapt quickly to novel situations.

Fatty acid profiles of citrus juice and seed lipids

Fatty acids from the juice and seeds of six citrus varieties were quantitatively determined for the region C 12–C 26. The total number of juice acids observed ranged from eighty-one (Key limes) to one hundred and two (Eureka lemons) and the total number of seed acids ranged from sixty-two (Valencia oranges) to sixty-eight (Key limes and Eureka lemons). Thirty-eight different iso and twenty-six anteiso acids were observed for the first time in edible plant material in concentrations ranging from less than 0·001 per cent to greater than 1 per cent. These single branched acids were verified by comparison of retention times with standards and by their characteristic mass spectrographic fragmentation patterns.

The Nature and Significance of Systox Residues in Plant Materials

The three previous papers of this series (Metcalf et al. 1954b, Fukuto et al. 1955, March et al. 1955) have presented information regarding the behavior of Systox as a systemic insecticide, and concerning its biochemical transformation in plants and animals. It is the purpose of this report to assess the effects of these developments upon the estimation and significance of Systox residues in edible plant materials.