Strategies and models for agricultural sustainability in developing Asian countries.

The green revolution of the 1960s and 1970s which resulted in dramatic yield increases in the developing Asian countries is now showing signs of fatigue in productivity gains. Intensive agriculture practiced without adherence to the scientific principles and ecological aspects has led to loss of soil health, and depletion of freshwater resources and agrobiodiversity. With progressive diversion of arable land for non-agricultural purposes, the challenge of feeding the growing population without, at the same time, annexing more forestland and depleting the rest of life is indeed daunting. Further, even with food availability through production/procurement, millions of marginal farming, fishing and landless rural families have very low or no access to food due to lack of income-generating livelihoods. Approximately 200 million rural women, children and men in India alone fall in this category. Under these circumstances, the evergreen revolution (pro-nature, pro-poor, pro-women and pro-employment/livelihood oriented ecoagriculture) under varied terms are proposed for achieving productivity in perpetuity. In the proposed 'biovillage paradigm', eco-friendly agriculture is promoted along with on- and non-farm eco-enterprises based on sustainable management of natural resources. Concurrently, the modern ICT-based village knowledge centres provide time- and locale-specific, demand-driven information needed for evergreen revolution and ecotechnologies. With a system of 'farm and marine production by masses', the twin goals of ecoagriculture and eco-livelihoods are addressed. The principles, strategies and models of these are briefly discussed in this paper.

Managing extreme natural disasters in coastal areas.

Extreme natural hazards, particularly the hydro-meteorological disasters, are emerging as a cause of major concern in the coastal regions of India and a few other developing countries. These have become more frequent in the recent past, and are taking a heavy toll of life and livelihoods. Low level of technology development in the rural areas together with social, economic and gender inequities enhance the vulnerability of the largely illiterate, unskilled, and resource-poor fishing, farming and landless labour communities. Their resilience to bounce back to pre-disaster level of normality is highly limited. For the planet Earth at crossroads, the imminent threat, however, is from a vicious spiral among environmental degradation, poverty and climate change-related natural disasters interacting in a mutually reinforcing manner. These, in turn, retard sustainable development, and also wipe out any small gains made thereof. To counter this unacceptable trend, the M.S. Swaminathan Research Foundation has developed a biovillage paradigm and rural knowledge centres for ecotechnological and knowledge empowerment of the coastal communities at risk. Frontier science and technologies blended with traditional knowledge and ecological prudence result in ecotechnologies with pro-nature, pro-poor and pro-women orientation. The rural communities are given training and helped to develop capacity to adopt ecotechnologies for market-driven eco-enterprises. The modern information and communication-based rural knowledge centres largely operated by trained semi-literate young women provide time- and locale-specific information on weather, crop and animal husbandry, market trends and prices for local communities, healthcare, transport, education, etc. to the local communities. The ecotechnologies and time- and locale-specific information content development are need-based and chosen in a 'bottom-up' manner. The use of recombinant DNA technology for genetic shielding of agricultural crops for coastal regions against abiotic stress (induced by the water- and weather-related natural disasters), strengthens the foundations of sustainable agriculture undertaken by the resource-poor small farm families.

EPR studies on gamma-irradiated barley seeds: identification of trapped electrons.

Electron paramagnetic resonance (EPR) studies were conducted on barley seeds exposed to normal (H(2)O) and deuterated (D(2)O) moisture, irradiated with 750 Gy at 77 K. Reported here, for the first time, are the trapped electrons formed on gamma-irradiation of seeds at 77 K. Electrons are stabilized/solvated with an increase in the moisture content (H(2)O/D(2)O) of seeds. The recombination of the trapped electron with radical cation gave intense thermoluminescence emission at 110 K. With the increase in temperature and the destruction of singlet, unmasking of an underlying heterogeneous population of free radicals was observed. These free radicals emanate mainly from the endosperm (approximately 95% by wt of the seed), whereas irradiated embryos show a broad multiplet of comparatively low amplitude. Radiolysis of carbohydrate, proteins (approximately 95% of endosperm), and lipids could possibly be responsible for the heterogeneous population of free radicals. Peroxyl radicals were also observed on annealing.

Mechanism of protection against radiation-induced DNA damage in plasmid pBR322 by caffeine.

PURPOSE: Caffeine (1,3,7-trimethyl xanthine), a dietary component, has been shown to have widely varying effects on DNA damage induced by UV and ionizing radiation, depending upon pre- or post-irradiation administration and its concentration. Caffeine administered post-UV irradiation is known to inhibit enzymatic repair of DNA lesions, leading to potentiation of damage, whereas its presence before or during irradiation elicits protection in a wide range of test systems: bacteria, cultured human cells, plant seeds and mouse. The purpose of this study is to test whether caffeine present during gamma-irradiation of plasmid DNA, a system devoid of replication and repair, could elicit protection by scavenging free radicals. MATERIALS AND METHODS: Plasmid pBR322 DNA was exposed to gamma-radiation in the presence or absence of caffeine at a dose-rate of 1.20 Gy min(-1) and damage measured as single-strand breaks. To understand the mechanisms of the observed protection, especially under oxic conditions, reaction of caffeine with superoxide radical (O(2)(-)), hydrogen peroxide (H(2)O(2)) and the deoxyribose peroxyl radical (ROO(*)) were studied. RESULTS: Irradiation of pBR322 was observed to induce a dose-dependent increase in single-strand breaks. Caffeine itself did not induce strand breaks but reduced radiation-induced strand breaks at micromolar to millimolar concentrations. Caffeine has been shown to react with the radiation-derived oxidants. The reaction rate constants observed were 7.5x10(1) M(-1) s(-1) with O(2)(-) 1.05x10(8) M(-1) s(-1) with ROO(*) and 8.8x10(1) M(-1) s(-1) with H(2)O(2). CONCLUSIONS: Caffeine effectively protects DNA against ionizing radiation in a system devoid of repair and replication machinery. Thus, DNA protection shown by caffeine is possibly due to the scavenging of radiation-derived primary as well as secondary reactive oxygen species, and this physicochemical protective pathway possibly pre-empts any subsequent inhibitory effect of caffeine on the enzymatic repair of DNA.

Differential modification by caffeine of oxygen-dependent and independent effects of gamma-irradiation on rat liver mitochondria.

PURPOSE: Following the demonstration that caffeine effectively competes with oxygen for electrons and also scavenges hydroxyl radicals and singlet oxygen, the differential modification of oxygen-dependent and independent effects of gamma-radiation by caffeine in membranes was examined, using rat liver mitochondria as a model system. MATERIALS AND METHODS: Mitochondria were isolated from the livers of Wistar rats and exposed to gamma-radiation in the dose range of 45-600 Gy (dose rate 15 Gy/min) in the presence or absence of caffeine. To examine the 'oxygen effect', post-irradiation incubation was carried out in the presence of oxygen or nitrogen in buffers saturated with the respective gases. Membrane damage was examined as lipid peroxidation (assessed as formation of thiobarbituric acid-reactive substances (TBARS), lipid hydroperoxides (LOOH) and conjugated dienes (CD), protein oxidation, depletion of protein thiols, superoxide dismutase or glutathione. RESULTS: Lipid peroxidation increased as a function of radiation dose, from 45 to 600 Gv. Post-irradiation incubation of mitochondria under nitrogen decreased the response, while incubation under oxygen saturation enhanced it significantly. The presence of caffeine during radiation exposure inhibited lipid peroxidation significantly as a function of concentration, in the range of 5 microM to 4 mM. The inhibition was highest with 4 mM of caffeine. Under oxic conditions, inhibition at 1 mM was significantly more than under anoxia. Anoxia was either ineffective or marginally increased peroxidation in the presence of caffeine. A similar observation was obtained when membrane damage was assessed as protein oxidation. Radiation-induced depletion of protein thiols was greatly enhanced by oxygen saturation and this was completely prevented by caffeine. This compound also protected against the radiation-induced loss of the antioxidant glutathione and the enzyme superoxide dismutase. CONCLUSIONS: The results suggest that caffeine effectively protected membranes against the oxic component of damage but may not do so for the anoxic component.

Genetic monitoring of the human population from high-level natural radiation areas of Kerala on the southwest coast of India. II. Incidence of numerical and structural chromosomal aberrations in the lymphocytes of newborns.

Cytogenetic studies using cord blood samples from newborns from high-level natural radiation areas of the Kerala coast in Southwest India have been in progress since 1986. A total of 963,940 metaphases from 10,230 newborns have been screened for various types of chromosomal aberrations. Comparison of 8,493 newborns (804,212 cells) from high-level natural radiation areas (dose rate >1.5 mGy/year) and 1,737 newborns (159,728 cells) from normal-level natural radiation areas (

Caffeine protects mice against whole-body lethal dose of gamma-irradiation.

Administration of caffeine (1,3,7-trimethylxanthine), a major component of coffee, to Swiss mice at doses of 80 or 100 mg/kg body weight 60 min prior to whole-body lethal dose of gamma-irradiation (7.5 Gy) resulted in the survival of 70 and 63% of animals, respectively, at the above doses in contrast to absolutely no survivors (LD-100/25 days) in the group exposed to radiation alone. Pre-treatment with a lower concentration of caffeine (50 mg/kg) did not confer any radioprotection. The protection exerted by caffeine (80 mg/kg), however, was reduced from 70 to 50% if administered 30 min prior to irradiation. The trend statistics reveal that a dose of 80 mg/kg administered 60 min before whole-body exposure to 7.5 Gy is optimal for maximal radioprotection. However, caffeine (80 mg/kg) administered within 3 min after irradiation offered no protection. While there is documentation in the literature that caffeine is an antioxidant and radioprotector against the oxic pathway of radiation damage in a wide range of cells and organisms, this is the first report demonstrating unequivocally its potent radioprotective action in terms of survival of lethally whole-body irradiated mice.

In vivo antigenotoxic effects of dietary agents and beverages co-administered with urethane: assessment of the role of glutathione S-transferase activity.

Antigenotoxic effects and changes in glutathione S-transferase (GST) activity were assessed in mice after oral co-administration of urethane (URE) with aqueous extracts of dietary vegetables (carrot, spinach and cabbage), spices (cinnamon, pepper, cumin, clove and cardamom), tea and coffee. The results of the genotoxicity assay (micronucleus test) demonstrated dose-related antigenotoxic effects after URE was co-administered with aqueous extracts of vegetables, spices, tea and coffee. Inhibition of GST activity was observed 4 h after treatment with URE alone. Co-administration of URE with extracts of vegetables, coffee and spices resulted in dose-related attenuation of the inhibitory effect of URE on GST activity. However, tea had no effect on inhibition of GST activity by URE. Hence an association between antigenotoxicity and GST activity could not be established.

Probing tenability of biochemical vis-a-vis physicochemical interpretations of modulation of radiation damage by caffeine and cysteine in barley.

Cysteine (an aminothiol) is known to protect against radiation damage, and is understood to do so by generating hydrogen peroxide which subsequently inhibits RNA synthesis. Our results showed inability of catalase to remove or reduce the magnitude of radioprotection by caffeine and/or cysteine at optimal/suboptimal temperatures in barley. This observation was adequately corroborated by data on frequency of chromosomal aberration, peroxidase activity and total protein content. On the contrary, catalase tended to enhance the radioprotective effectiveness of cysteine. Macromolecular synthetic patterns in caffeine and/or cysteine treated embryos were too inconsistent to permit a logical conclusion with regard to their positive involvement in the biochemical pathway of chemical modification of radiation damage. On the other hand, mutually annihilatory reaction hypothesis based on physico-chemical principles provides a satisfactory explanation for the observed effects.

Radioprotection of mice following garlic pretreatment.

Freshly prepared aqueous extract of garlic was tested in mice for its possible in vivo protective effect against gamma-radiation-induced chromosomal damage. In the same animals, the changes in the sulphydryl content and glutathione S-transferase activity were evaluated. Three doses of garlic extract [125, 250 and 500 mg kg-1 body weight (bw)] were administered orally for five consecutive days and the animals were exposed to 0.25, 0.5, 1.0 and 2.0 Gy gamma-radiation 2 h after the final feeding. The results of the bone marrow micronucleus test revealed that pretreatment with garlic extract was effective in reducing gamma-radiation-induced chromosomal damage. Against 0.25 Gy gamma-radiation, a high dose of 500 mg kg-1 bw garlic extract was required to significantly reduce the chromosomal damage. All the three doses of garlic extract were effective in exerting a protective effect against 0.5, 1.0 and 2.0 Gy gamma-radiation. However a dose-related effect was observed only against 2.0 Gy. The sulphydryl content and glutathione S-transferase activity registered a significant increase after either pretreatment with garlic with extract or irradiation. In the garlic extract pretreated irradiated animals, a significant reduction was observed in the sulphydryl content and glutathione S-transferase activity.

Caffeine as an antioxidant: inhibition of lipid peroxidation induced by reactive oxygen species.

Caffeine (1,3,7-trimethyl xanthine), an ingredient of coffee, has been investigated for its potential antioxidant activity against oxidative damage to rat liver microsomes. Such damage was induced by three reactive oxygen species of cardinal importance in causing membrane damage in vivo namely hydroxyl radical (.OH), peroxyl radical (ROO.) and singlet oxygen (1O2). The results obtained showed that caffeine was an effective inhibitor of lipid peroxidation, at millimolar concentrations, against all the three reactive species. The extent of inhibition was high against peroxidation induced by .OH, medium against 1O2 and low against ROO. In general, the antioxidant ability of caffeine was similar to that of the established biological antioxidant glutathione and significantly higher than ascorbic acid. Investigations into the possible mechanisms involved in the observed antioxidant effect reveal that the quenching of these reactive species by caffeine may be one of the possible factor responsible. The rate constant of caffeine with .OH was 7.3 x 10(9) M-1 s-1 and with 1O2 it was 2.9 x 10(7) M-1 s-1. Considering their potential for damage, half-life estimates and generation in biological systems, the ability of caffeine to inhibit oxidative damage induced by these reactive species in membranes suggest one more positive attribute of caffeine, whose daily intake as coffee may be considerable in most populations.

Mechanisms of protection by buthionine sulphoximine against gamma-ray-induced micronuclei in polychromatic erythrocytes of mouse bone marrow.

The effect of pretreatment with buthionine sulphoximine (BSO) on the radiosensitivity of mouse bone marrow cells was studied using the in vivo micronucleus test. Varying concentrations of BSO were injected into mice by intraperitoneal injection 2 h before irradiation, and the frequency of micronuclei in polychromatic erythrocytes (MnPCEs) of bone marrow were scored. Treatment with BSO resulted in a significant reduction (41% at 20 mg/kg body weight) in the frequency of micronuclei induced by 1 Gy gamma-rays. Reduction was observed in cells sampled at 24, 30 and 48 h postirradiation with no apparent effect on the ratio of poly- to normo-chromatic erythrocytes in BSO-treated versus control groups. Glutathione levels in the bone marrow of BSO-treated animals 2 h after a single injection were found to be unaltered. The protective effect of BSO was not observed if it was given either immediately or 2 h after irradiation. Based on these and earlier findings it seemed as if BSO molecules may be involved in physicochemical reactions with reactive species generated in the system by irradiation. BSO showed relatively high reaction rate constants with hydroxyl radical (.OH, 2.5 x 10(9) dm3 mol-1s1, calculated on the basis of competition kinetics) and with singlet oxygen (1O2, 4.3 x 10(7) dm3 mol-1s-1 but a lower rate constant with hydrated electrons (< or = 5.0 x 10(6) dm3 mol-1s1). Based on half-life estimates, transients formed and potential for damage to biomolecules, .OH and 1O2 seemed to be the possible species responsible. In vitro studies reveal that BSO has significant abilities to protect DNA against single-strand breaks and lipid peroxidation induced by 1O2 in microsomal membranes. This supports our hypothesis that BSO may be involved in scavenging the reactive species generated and that besides .OH, 1O2 may also be a major player in radiation damage.

Radioprotective and antioxidant action of caffeine: mechanistic considerations.

Caffeine, a major constituent of coffee and other beverages has significant abilities to scavenge highly reactive free radicals and excited states of oxygen and to protect crucial biological molecules against these species. This is one of the possible reasons why caffeine acts as a radioprotector against oxygen-dependent ('oxic') pathway of radiation damage and as an antimutagen/anticarcinogen under certain conditions. The possible physicochemical and molecular mechanisms of caffeine action are briefly reviewed in the light of the recent findings.

Mechanistic aspects of modification of radiobiological damage in barley seeds by glutathione and buthionine sulfoximine.

Buthionine sulfoximine (BSO) enhances the radiosensitivity of in vitro mammalian cells, possibly by inhibiting de novo biosynthesis of glutathione (GSH); however, administration of BSO to intact animals results in no effect or possibly radioprotection. Keeping in view that BSO affords radioprotection its physico-chemical action in dry (metabolically inert) and pre-soaked (metabolizing) barley seeds has been investigated with a view that the effects of GSH and BSO on the radiation-induced O2-dependent and - independent components of damage could be unambiguously resolved. It was observed that (i) BSO does not inhibit the uptake of GSH in dry or metabolizing seeds, (ii) BSO also, like GSH, affords radioprotection against post-irradiation O2-dependent damage, and (iii) both additives enhance the O2-independent (i.e. N2- or N2O-mediated) component of damage. An equimolar mixture of these two additives also behaves as either alone on the oxic and anoxic components of radiation damage. Since GSH more efficiently reacts with electrons than it donates an H-atom to the damaged target molecules, and the glutamyl moiety is common to both GSH and BSO, physico-chemical mechanisms possibly involved in the differential modification of oxic and anoxic components are briefly discussed.

In vivo radioprotection with garlic extract.

Garlic extract was evaluated in the mouse bone marrow micronucleus test for its possible protective effects against gamma-radiation-induced chromosomal damage. Together with this, biochemical assays were carried out to determine the changes in sulfhydryl content and glutathione S-transferase activities. Three doses of freshly prepared garlic extract (125, 250 and 500 mg/kg b.w.) were orally administered for 5 consecutive days, and the animals were irradiated 2 h after the final feeding. The results of the micronucleus test demonstrated that pre-treatment with garlic extract can lead to significant dose-related reductions in the frequencies of gamma-radiation-induced (2 Gy) micronucleated polychromatic erythrocytes. The anticlastogenic effect of garlic extract was observed against lower radiation doses of 0.5 and 1 Gy, but not 0.25 Gy. Significant increases in the sulfhydryl content and glutathione S-transferase activity were observed after either pre-treatment with garlic extract or irradiation. However, the irradiated garlic-extract pre-treated animals showed a significant reduction in sulfhydryl content and glutathione S-transferase activities.

Post-exposure radioprotection by Chlorella vulgaris (E-25) in mice.

Oral administration of an algal mutant C. vulgaris E-25, 1 hr before or immediately after exposure to sublethal gamma-rays increased the number of endogenous spleen colony forming units (E-CFU). The magnitude of radioprotection was dependent on both, the dose of C. vulgaris fed and the time of administration. An optimal E-CFU was observed when 500 mg/kg body wt. of C. vulgaris was fed 1 hr before or immediately after irradiation. Significant recovery was observed in the number of bone marrow cells and the spleen weight. LD50/30 for Chlorella pre- and post-treated mice were 8.66 and 9.0 Gy, respectively compared to the control value of 7.8 Gy. The dose reduction factor (DRF) was 1.11 and 1.15 for pre-treated and post-treated mice respectively.

Role of chlorophyllin as an in vivo anticlastogen: protection against gamma-radiation and chemical clastogens.

Chlorophyllin was evaluated in the mouse bone marrow micronucleus test for its possible protective effects against chromosomal damage induced by gamma-radiation, cyclophosphamide, N-nitroso-N-ethylurea and urethane. Three doses of chlorophyllin (50, 100 and 200 mg/kg, b.w.) were orally administered to mice 2 h before exposure to the clastogens under investigation. The results obtained demonstrated that chlorophyllin can significantly reduce the incidence of micronucleated polychromatic erythrocytes induced by gamma-radiation (1.15 Gy) and all the three chemical clastogens. However with the exception of cyclophosphamide there was no indication of a dose response for the in vivo anticlastogenic effects of chlorophyllin.

Evaluation of radioprotective action of a mutant (E-25) form of Chlorella vulgaris in mice.

The possible role of orally fed Chlorella vulgaris (E-25) in modulating the gamma-ray induced chromosomal damage in whole-body irradiated mice was evaluated using a micronucleus test. Different doses of E-25 were administered either chronically (once, twice or thrice a day for 28 days) or as single acute doses before/after irradiation. A significant radioprotective effect was observed in both acute and chronic pretreatments, but only at doses above 400 mg/kg body weight. However, in mice that received E-25 (500 mg/kg) three times a day for 28 days, there was no protective effect, and a significant loss in their body weight was observed. Interestingly, E-25 afforded significant radioprotection even when it was administered within 0.4 hr after irradiation.

Protective effects of chlorogenic acid, curcumin and beta-carotene against gamma-radiation-induced in vivo chromosomal damage.

The mouse bone marrow micronucleus test was carried out to evaluate the possible role of the dietary constituents chlorogenic acid (CGA), curcumin (CR) and beta-carotene (BC) in modulating the in vivo chromosomal damage induced by gamma-radiation. The results obtained suggest that oral administration of CGA (50, 100 and 200 mg/kg b.w.), CR (5, 10 and 20 mg/kg b.w.) and BC (0.5 and 2.5 mg/kg b.w.) to mice can significantly reduce the frequencies of micronucleated polychromatic erythrocytes (Mn PCEs) induced by whole body exposure to gamma-radiation (1.15 Gy; 0.05 Gy/s). With CGA and CR, this effect was observed after a single administration either 2 h before or immediately after irradiation. However, with BC a 7-day feeding before irradiation was necessary to obtain a significant reduction in the incidence of Mn PCEs. The protective effects of CGA, CR and BC were observed in bone marrow cells sampled 24, 30 and 48 h after exposure to radiation.