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At least 991 records · Page 55Linked to original sources
PubMed2001

[Development of a cultivation technology and selection of leaf vegetable cultures for space greenhouse].

We plan to perform space experiments on development of a technology for cultivation of leaf vegetables that might be a component of future life support systems for space crews. For this purpose, we are going to fly research greenhouses with the crop area from 0.03 up to 0.1 m2 inside the universal docking module of the ISS Russian segment. To prepare for future space experiments, ground investigations were made in order to compare crop capacity of various artificial soils used to grow leaf vegetables in greenhouse Svet. Useful life of root module Svet can be extended with a new technology based on resupply of fibrous substrate with nutrients. The most effective volume of soil per a plant was determined which sustains high productivity of leaf vegetables in Svet. To select leaf vegetables for in-space cultivation, we conducted investigations of productivity, morphometric and biochemical characteristics, and palatability of 18 cultures including alternative greens highly popular in Japan and China which have been earlier tested neither in laboratory nor in space within the closed eco-system projects. We would prioritize mizuna, pak choi, tatsoi, rapina or broccoli raab, and red giant mustard as objects for in-space investigations.

Agrochemicals↗
PubMedDate not supplied

[The role of higher plants in the human biological life support system].

This paper discusses the functional characteristics of the man-plant-mineralization system and the environment it forms when it is supplemented with a photoautotrophic component including higher plants and algae. The functional characteristics of the higher plant component were studied when it operated first in an independent cultivation mode, then coupled with a biological system of human and biocomplex waste mineralization, and finally with a human gas exchange system and Chlorella containing photosynthetic reactors. This approach demonstrated for the first time that Chlorella and higher plants can normally work in a common autosphere. The paper also presents quantitative data about the use of higher plants in a biological life support system. Data analysis shows that the total plant yield did not diminish when the system was closed and man, mineralization system and algal reactors were connected. However although the total photosynthetic productivity remained unchanged, the yield of useful crops decreased. This points to a complex nature of the above effects, the causes of which remain so far inexplicable and require further study.

Aerospace Medicine↗
PubMedDate not supplied

Toxicogenomic approach to endocrine disrupters: identification of a transcript profile characteristic of chemicals with estrogenic activity.

Public concerns have been raised in recent years over the possible adverse effects that may result from exposure to chemicals in the environment that have the potential to interfere with the normal function of the endocrine system in wildlife and humans ("endocrine disrupters"). Regulations have been established that require the testing of pesticides used in food crops and drinking water contaminants, for estrogenicity and other hormonal activities. In the United States, the U.S. EPA proposed the Endocrine Disrupter Screening Program, which consists of a Tier 1 screening battery of tests that is designed to identify chemicals capable of interacting with various hormonal systems, and different Tier 2 testing assays that are designed to verify and broaden the Tier 1 results. We identify 2 main problems with this approach: (1) the fact that the developmental stages that are the most susceptible to endocrine disruption are not represented in the screening tier, mainly because developmental effects tend to be latent, and there is no way to economically screen in developing models; and (2) the expense to screen each chemical to be included in this program. Thus, the need arises for an accurate, rapid, and cost effective method for assessing the potential endocrine activity of multiple chemicals during development. We hypothesize that the largely latent developmental effects of some endocrine disruptors are preceded by immediate changes in gene expression in the embryo and fetus. Therefore, an approach to assess the potential estrogenic (and other steroid hormonal) activity of different compounds is to identify those patterns of gene expression elicited in a tissue/organ exposed to these particular classes of chemicals. In this paper, the potential utility of such an approach for screening and better understanding of mechanism of action for specific chemicals with endocrine disrupter activities is presented, using as an example chemicals with estrogenic activity.

Animals↗
PubMed1998

A method for the assessment of the risk of wheat lodging

A model of the wheat canopy/root/soil system has been developed, which calculates the risk of stem and root lodging from crop parameters and soil characteristics. For a large number of wind speed and rainfall realisations the model determines whether or not stem lodging will occur by comparing the wind induced bending moment at the base of an individual shoot with the stem base failure moment. Similarly, whether or not root lodging will occur is ascertained by comparing the wind induced base bending moment of the whole plant with the plant's root failure moment. The overall probability of lodging is determined from the proportion of wind speed and rainfall realisations for which lodging is predicted to occur. For differently managed wheat crops the model correctly predicted lodging in 21 of the 30 lodged crops and nil lodging for 38 of the 42 standing crops. The model showed that both stem and root lodging may occur given suitable circumstances. The state of the crop was as important as the prevailing weather for influencing lodging risk. A relatively small number of crop parameters were of major importance in the lodging process. These include the shoot's centre of gravity height, natural frequency, stem base radius and failure yield stress, and the plant's shoot number, root plate diameter and structural rooting depth. In addition, the importance of soil, particulary clay content, in influencing anchorage was illustrated. Recommendations for further improvement of the model include improvement of the soil strength calculation. Copyright 1998 Academic Press

Journal Article↗
PubMed2005

Assessment of MODIS-EVI, MODIS-NDVI and VEGETATION-NDVI composite data using agricultural measurements: an example at corn fields in western Mexico.

Although several types of satellite data provide temporal information of the land use at no cost, digital satellite data applications for agricultural studies are limited compared to applications for forest management. This study assessed the suitability of vegetation indices derived from the TERRA-Moderate Resolution Imaging Spectroradiometer (MODIS) sensor and SPOT-VEGETATION (VGT) sensor for identifying corn growth in western Mexico. Overall, the Normalized Difference Vegetation Index (NDVI) composites from the VGT sensor based on bi-directional compositing method produced vegetation information most closely resembling actual crop conditions. The NDVI composites from the MODIS sensor exhibited saturated signals starting 30 days after planting, but corresponded to green leaf senescence in April. The temporal NDVI composites from the VGT sensor based on the maximum value method had a maximum plateau for 80 days, which masked the important crop transformation from vegetative stage to reproductive stage. The Enhanced Vegetation Index (EVI) composites from the MODIS sensor reached a maximum plateau 40 days earlier than the occurrence of maximum leaf area index (LAI) and maximum intercepted fraction of photosynthetic active radiation (fPAR) derived from in-situ measurements. The results of this study showed that the 250-m resolution MODIS data did not provide more accurate vegetation information for corn growth description than the 500-m and 1000-m resolution MODIS data.

Crops, Agricultural↗
PubMed2007

Toxicity of three pesticides individually and in mixture to larval grass shrimp (Palaemonetes pugio).

This study examined the toxicity of three pesticides, singly and in mixture, to grass shrimp (Palaemonetes pugio) larvae. The pesticides included atrazine, an herbicide used on turf grass and field crops; fipronil, a persistent insecticide used against termites and fire ants; and imidacloprid, a systemic insecticide used in agricultural and home products. Fipronil was the most toxic to shrimp larvae with a 96-h LC50 of 0.68microg/L (95% CI 0.57-0.79microg/L). Shrimp larvae were less sensitive to imidacloprid with a 96-h LC50 of 308.8microg/L (95% CI 273.6-348.6microg/L). Atrazine was non-toxic to shrimp larvae at concentrations up to 10,000microg/L. In mixtures, fipronil plus atrazine and imidacloprid plus atrazine had no change in toxicity compared to fipronil and imidacloprid tested singly. Similarly, a fipronil/imidacloprid mixture did not show greater than additive toxicity. However, when atrazine was added to the fipronil/imidacloprid mix, greater than additive toxicity occurred.

Animals↗
PubMed2004

Immunostimulating effects of sugar cane extract on X-ray radiation induced immunosuppression in the chicken.

The present study was undertaken to evaluate the effect of sugar cane (Saccharum officinarum L.) extract (SCE) on the immune system of X-ray immunosuppressed chickens. SCE (500 mg/kg/day) was administrated into the crop of 3-week-old chickens for three consecutive days before or after irradiation. The results indicated that administration of SCE before or after whole body X-ray irradiation enhanced both primary and secondary immune responses in chickens immunized with sheep red blood cells and Brucella abortus (BA) as well as cell-mediated immunity measured by delayed type hypersensitivity to human gamma-globulin.

Adjuvants, Immunologic↗
PubMed2000

Exploiting the full potential of disease-resistance genes for agricultural use.

Effective and sustained control of fungal pathogens and nematodes is an important issue for all agricultural systems. Global losses caused by pathogens are estimated to be 12% of the potential crop production [1], despite the continued release of new resistant cultivars and pesticides. Furthermore, fungi are continually becoming resistant to existing resistance genes and fungicides, and a few of the pesticides are being withdrawn from the market for environmental reasons. In addition to reducing crop yield, fungal diseases often lower crop quality by producing toxins that affect humans and human health. Additional methods of disease control are therefore highly desirable. Breeding programs based on plant disease-resistance genes are being optimized by incorporating molecular marker techniques and biotechnology. These efforts can be expected to result in the first launches of new disease-resistant crops within the next five years.

Agriculture↗
PubMed2006

Use of Monte Carlo analysis to characterize nitrogen fluxes in agroecosystems.

Intensive agricultural systems are largely responsible for the increase in global reactive nitrogen compounds, which are associated with significant environmental impacts. The nitrogen cycle in agricultural systems is complex and highly variable, which complicates characterization in environmental assessments. Appropriately representing nitrogen inputs into an ecosystem is essential to better understand and predict environmental impacts, such as the extent of seasonally occurring hypoxic zones. Many impacts associated with reactive nitrogen are directly related to annual nitrogen loads, and are not adequately represented by average values that de-emphasize extreme years. To capture the inherent variability in agricultural systems, this paper employs Monte Carlo analysis (MCA) to model major nitrogen exports during crop production, focusing on corn-soybean rotations within the U.S. Corn Belt. This approach yields distributions of possible emission values and is the first step in incorporating variable nutrient fluxes into life cycle assessments (LCA) and environmental impact assessments. Monte Carlo simulations generate distributions of nitrate emissions showing that 80% of values range between 15 and 90 kg NO39-) N/ha (mean 38.5 kg NO3(-) N/ha; median 35.7 kg NO3(-) N/ha) for corn fields and 5-60 kg NO3(-) N/ha (mean 20.8 kg NO3(-) N/ha; median 16.4 kg NO3(-) N/ha) for soybean fields. Data were also generated for grain and residue nitrogen, N2O, NO(x), and NH3. Results indicate model distributions are in agreement with available measured emissions.

Ecosystem↗
PubMed2002

Resistance and susceptibility of plants to fungal pathogens.

Plants are under continuous threat of infection by pathogens endowed with diverse strategies to colonize their host. Comprehensive biochemical and genetic approaches are now starting to reveal the complex signaling pathways that mediate plant disease resistance. Initiation of defense signaling often involves specific recognition of invading pathogens by the products of specialized host resistance (R) genes. Potential resistance signaling components have been identified by mutational analyses to be required for specific resistance in the model Arabidopsis and some crop species. Strikingly, many of the components share similarity to that of innate immune systems in animals. Evidence is also accumulating that plant pathogens have a number of ways to evade host defenses during the early stages of infection, similar to animal pathogens. These strategies are becoming much better understood in a number of plant-pathogen interactions. In this review, we focus on the current knowledge of host factors that control plant resistance and susceptibility to fungal pathogens. The knowledge accumulated in these studies will serve a fundamental basis for combating diseases in strategic molecular agriculture.

Fungal Proteins↗
PubMed2004

Trichoderma species--opportunistic, avirulent plant symbionts.

Trichoderma spp. are free-living fungi that are common in soil and root ecosystems. Recent discoveries show that they are opportunistic, avirulent plant symbionts, as well as being parasites of other fungi. At least some strains establish robust and long-lasting colonizations of root surfaces and penetrate into the epidermis and a few cells below this level. They produce or release a variety of compounds that induce localized or systemic resistance responses, and this explains their lack of pathogenicity to plants. These root-microorganism associations cause substantial changes to the plant proteome and metabolism. Plants are protected from numerous classes of plant pathogen by responses that are similar to systemic acquired resistance and rhizobacteria-induced systemic resistance. Root colonization by Trichoderma spp. also frequently enhances root growth and development, crop productivity, resistance to abiotic stresses and the uptake and use of nutrients.

Fungi↗
PubMed1997

Cannabis policy in Australia and New Zealand.

This paper describes and compares current developments in policies to deal with cannabis in Australia and New Zealand. Both countries are bound by international conventions to control cannabis and in each case cannabis use, possession, cultivation and supply is illegal. In both countries almost all the supply is grown locally and patterns of use and health concerns appear to be similar. Strategies used to deal with cannabis include: demand reduction through enforcement of legislation, drug education and treatment; supply reduction through enforcement of legislation and crop recovery operations; and harm reduction through diversion of some offenders from the courts system, lenient enforcement policies for users and, in Australia, the formal decriminalization of cannabis use in two states/territories and de facto decriminalization in another. Australia has had a co-ordinated national drugs policy with a stated harm reduction focus for over a decade, while in New Zealand efforts to co-ordinate policy have been delayed by ongoing debates about cannabis's harm potential and what constitutes an appropriate approach. However, a national drugs policy with a professed harm reduction focus is currently being finalized. Despite these developments, government cut-backs and international and local prohibitionist influences on policy in both countries suggest that a harm reduction model may not necessarily be secure.

Journal Article↗
PubMed2003

MOsDB: an integrated information resource for rice genomics.

The MIPS Rice (Oryza sativa) database (MOsDB; http://mips.gsf.de/proj/rice) provides a comprehensive data collection dedicated to the genome information of rice. Rice (O. sativa L.) is one of the most important food crops for over half the world's population and serves as a major model system in cereal genome research. MOsDB integrates data from two publicly available rice genomic sequences, O. sativa L. ssp. indica and O. sativa L. ssp. japonica. Besides regularly updated rice genome sequence information, MOsDB provides an integrated resource for associated analysis data, e.g. internal and external annotation information as well as a complex characterization of all annotated rice genes. The MOsDB web interface supports various search options and allows browsing the database content. MOsDB is continuously expanding to include an increasing range of data type and the growing amount of information on the rice genome.

DNA Transposable Elements↗
PubMed1998

Spatial heterogeneity and insect adaptation to toxins.

Behavioral responses of insect herbivores to toxins are examined in managed and natural systems with reference to two important but largely ignored factors: heterogeneity in toxin distributions and the nature of the relationship between behavioral responses and physiological adaptation to the same toxins. Heterogeneous toxin distributions, which provide the opportunity for behavioral responses, are ubiquitous in managed and natural systems. Insect herbivores have evolved a wide variety of behavioral responses to such toxins. The nature of behavioral responses reflects toxin apparency, mode of action, and the extent to which sublethal effects influence behavior. The interaction between these behavioral responses to heterogeneously distributed toxins and physiological mechanisms of tolerance has influenced the evolution of insecticide resistance in managed systems and the evolution of plant defensive strategies in natural systems. An understanding of this interaction could lead to more evolutionarily stable methods of crop protection.

Journal Article↗
PubMed2006

Propanil exposure induces delayed but sustained abrogation of cell-mediated immunity through direct interference with cytotoxic T-lymphocyte effectors.

The postemergent herbicide propanil (PRN ; also known as 3,4-dichloropropionanilide) is used on rice and wheat crops and has well-known immunotoxic effects on various compartments of the immune system, including T-helper lymphocytes, B lymphocytes, and macrophages. It is unclear, however, whether PRN also adversely affects cytotoxic T lymphocytes (CTLs) , the primary (1 degrees ) effectors of cell-mediated immunity. In this study we examined both the direct and indirect effects of PRN exposure on CTL activation and effector cell function to gauge its likely impact on cell-mediated immunity. Initial experiments addressed whether PRN alters the class I major histocompatibility complex (MHC) pathway for antigen processing and presentation by antigen-presenting cells (APCs) , thereby indirectly affecting effector function. These experiments demonstrated that PRN does not impair the activation of CTLs by PRN-treated APCs. Subsequent experiments addressed whether PRN treatment of CTLs directly inhibits their activation and revealed that 1 degrees alloreactive CTLs exposed to PRN are unimpaired in their proliferative response and only marginally inhibited in their lytic activity. Surprisingly, secondary stimulation of these alloreactive CTL effectors, however, even in the absence of further PRN exposure, resulted in complete abrogation of CTL lytic function and a delayed but significant long-term effect on CTL responsiveness. These findings may have important implications for the diagnosis and clinical management of anomalies of cell-mediated immunity resulting from environmental exposure to various herbicides and other pesticides.

Animals↗
PubMed1999

Fungal spores: hazardous to health?

Fungi have long been known to affect human well being in various ways, including disease of essential crop plants, decay of stored foods with possible concomitant production of mycotoxins, superficial and systemic infection of human tissues, and disease associated with immune stimulation such as hypersensitivity pneumonitis and toxic pneumonitis. The spores of a large number of important fungi are less than 5 microm aerodynamic diameter, and therefore are able to enter the lungs. They also may contain significant amounts of mycotoxins. Diseases associated with inhalation of fungal spores include toxic pneumonitis, hypersensitivity pneumonitis, tremors, chronic fatigue syndrome, kidney failure, and cancer.

Animals↗
PubMed2002

Possibilities for reducing nitrate leaching from agricultural land.

Agricultural soil is a contributor of nitrate to natural waters. High nitrate levels in water leached from soils are related to high nitrate concentrations in drinking water, and excess levels change the ecological balance of rivers and lakes. In this paper, sound solutions to the major environmental issue of limiting nitrate leaching by modifying agricultural practices are discussed. The causes of nitrate leaching from agricultural land are briefly explained and existing measures for the reduction of nitrate losses are described, analyzed and evaluated. Reduction of nutrient leaching is not a question of organic or conventional farming, but rather of the introduction and use of appropriate countermeasures. We propose the following guiding principles to minimize leaching from agricultural soils. To some extent these principles require a new way of thinking: i) environmental indexing of fields and consideration of spatial variability within fields in relation to their contribution to leaching losses within a catchment; ii) reduction of nitrogen inputs to soil to levels slightly below those expected to give the optimum yield by applying less nitrogen fertilizer and by a further reduction in animal density; and iii) use of a range of counter-measures (catch crops, minimum tillage, control of biological processes, etc.) depending on how sensitive the farming system, soil and climate are to the risk of nitrate leaching.

Agriculture↗
PubMed2000

Metabolic control analysis of de novo sunflower fatty acid biosynthesis.

We have obtained a simulation of the final steps of de novo fatty acid biosynthesis in sunflower control line RHA-274. For this simulation, we have used data from the evolution of fatty acids during seed formation and from the biochemical characterization of beta-keto-acyl-ACP synthetase II (FASII), stearoyl-ACP desaturase (SAD) and acyl-ACP thioesterase activities and the program GEPASI (based on the metabolic control-analysis theory). When physiological data from high- and medium-stearic acid mutants seed development were used with this model the predicted changes in SAD and TE were very similar to those actually found in the biochemical characterization of these mutants. However, the model had to be modified when results from high-palmitic mutants, accumulating unusual fatty acids like palmitoleic, asclepic and palmitolinoleic acids, were used. The emerging model, that fits all of our results, predicts the existence of a dynamic channelling between the FASII complex and SAD, that channelling being responsible for the alternative pathway starting with the desaturation of palmitic acid by the stearoyl-ACP desaturase. This channelling is consistent with our previous results. For instance, the determination of SAD activity on sunflower seed crude extracts only rendered oleic acid when the stearic acid used as a substrate was obtained from a KASII assay, but not when the stearic acid came from in vitro synthesis using acyl-ACP synthetase from Escherichia coli. This theoretical approximation will be very useful in predicting the evolution of the system when introducing new or modified activities; similar approximations in other oil-seed crops could be of great interest.

3-Oxoacyl-(Acyl-Carrier-Protein) Synthase↗