Showing papers in "Current Science in 2000"

An introduction to the proper orthogonal decomposition

Abstract: A tutorial is presented on the Proper Orthogonal Decomposition (POD), which finds applications in computationally processing large amounts of high-dimensio nal data with the aim of obtaining low-dimensional descriptions that capture much of the phenomena of interest The discrete version of the POD, which is the singular value decomposition (SVD) of matrices, is described in some detail The continuous version of the POD is outlined Low-rank approximations to data using the SVD are discussed The SVD and the eigenvalue decomposition are compared Two geometric interpretations of the SVD/POD are given Computational strategies (using standard software) are mentioned Two numerical examples are provided: one shows low-rank approximations of a surface, and the other demonstrates simple a posteriori analysis of data from a simulated vibroimpact system Some relevant computer code is supplied

Heparinoid-active sulphated polysaccharides from marine algae as potential blood anticoagulant agents.

Abstract: Anticoagulant properties of marine algae have been extensively studied for the last 60 years. Sulphated polysaccharides (SPS) of three major divisions of marine algae, viz. Rhodophyta, Phaeophyta and Chlorophyta are reported to have such properties. Some of the active components have been chemically well characterized. Sulphated galactans and fucoidan sulphates from red and brown algae, respectively, and different sugar sulphates like arabinan, rhamnan sulphates, etc. from green algae are the active molecular species identified. Activity is related to the molecular size, type of sugar and sulphate content of the active component. Sulphate position, type of linkage and molecular geometry are also known to have a role in activity. The proposed mechanisms of action are predominantly on HC-II mediated antithrombin activities, direct antithrombin action (thrombin–fibrinogen complex) and minor AT-III involvements. Little anti-factor Xa and fibrinolytic activities are also proposed. Therapeutic interest of algal SPS as anticoagulant has recently been in focus. In future, algal SPS can be developed as anticoagulant/antithrombotic agents or could be used as a model for the same.

Deforestation and land use changes in Western Ghats, India

Abstract: We estimated changes in forest cover between 1973 and 1995 in the southern part of the Western Ghats using satellite data. The study area of approximately 40,000 km2 showed a loss of 25.6% in forest cover over 22 years. The dense forest was reduced by 19.5% and open forest decreased by 33.2%. As a consequence, degraded forest increased by 26.64%. There has been a great deal of spatial variability in the pattern of forest loss and land use change throughout the region. Our estimates of deforestation in the region for the contemporary period are the highest reported so far.

Synthetic seed: prospects and limitations.

Abstract: The synthetic seed technology has been developed to use somatic embryos and/or other micropropagules as seed analogues successfully in the field or greenhouse, and their mechanical planting at a commercial level. The technology provides methods for preparation of seed analogues called synthetic seeds or artificial seeds from the micropropagules like somatic embryos, axillary shoot buds, apical shoot tips, embryogenic calli as well as protocorm or protocormlike bodies. For the last fifteen years, intensive research efforts have been made on synthetic seed production in a number of plant species. Despite these researches, practical implementation of the technology is yet to be fully realized due to limitations encountered with the production, development, maturation and subsequent conversion of the micropropagules into plantlets under in vitro or ex vitro conditions. The present article focuses on the technology developed, its achievements and prospects as well as limitations resisting the application of the synthetic seed technology.

Nitrates, agriculture and environment

Abstract: Nitrogen is a very important nutrient element in agriculture. In soils it occurs in organic and inorganic forms. Inorganic N occurs primarily as nitrate in arable soils. Nitrate is subject to various processes such as plant uptake, leaching from soils among others. Leaching of nitrates from soils is a global phenomenon. Although a lot of attention has been paid world over on this phenomenon, its importance is being felt recently in developing countries like India where the emphasis has been on the problems related to increased food production from limited cultivable land. However, maintaining delicate agro-ecosystems in order to achieve sustainable agricultural productivity while protecting the environment has attracted the attention of scientists and policy makers. This article discusses the phenomenon of nitrate leaching from soils, its impact on man and animals and means to minimize the leaching. Nitrate leaching could be a major threat to environment in different agricultural situations. By proper management of agricultural systems, these leaching losses could be reduced and pollution problems can be minimized.

Seed storage proteins and approaches for improvement of their nutritional quality by genetic engineering.

Abstract: Seed storage proteins of grain crops meet the major dietary protein requirement of over half of the world population. However, seed proteins in general are deficient in some essential amino acids and hence are of poor nutritional quality. Therefore, intensive research is going on to isolate and characterize these proteins and their genes, and to produce transgenic crop plants with modified seed protein genes, with a view to improving their nutritive value as human food and animal feed. Many seed storage protein genes from cereals, legumes and oil seeds have been isolated, sequenced and their regulation has been studied by promoter deletion assay in transgenic plants. The amino acid composition of seed proteins of some transgenic crops has been marginally improved by modifying these genes for more methionine and lysine codons by sitedirected mutagenesis or by introducing heterologous genes. The synthesis, processing and targeting of the introduced gene products and their stable expression in successive generations of transgenic plants have also been studied. The potentiality of such genetic engineering approaches has been amply demonstrated. But problems of control over copy number and site of integration of the foreign gene and the position effect of the changes in the amino acid in the polypeptide chain on the final level of expression and deposition of the correctly processed storage protein remains unsolved. More basic research is needed before large-scale application of this approach for improvement of nutritional quality of seed proteins becomes possible.

Organic carbon stock in Indian soils and their geographical distribution.

Abstract: The first ever estimate of organic carbon (OC) stock in Indian soils was 24.3 Pg (1 Pg = 10 g) based on 48 soil series taking into account of a few major soils. The present OC stock has been estimated as 63 Pg in the first 150 cm depth of soils. Soils with their geographical distribution through the country were used for computing soil organic carbon (SOC) stock in different depths in various physiographic regions. To sustain the quality and productivity of soils, the knowledge of OC in terms of its amount and quality in soils is essential. This has more relevance in soils of the tropical and subtropical parts of the globe, including the Indian sub-continent. SOC stock appears to be a single parameter that can help effectively in prioritizing the area for restoring soil health.

Plant productivity determinants beyond minerals, water and light: Piriformospora indica - a revolutionary plant growth promoting fungus.

Abstract: Biotic factors, along with the more obvious abiotic factors, determine and greatly influence the producti vity and health of the plants. Arbuscular mycorrhizal fungi, AMF, the root-interacting predominant microbiota play an indispensable role in upgrading plant growth vigour and survival. However, the nonavailability of the axenic culture is a great bottleneck for the fundamental studies and their biotechnological applications. Piriformospora indica is a newly described axenically cultivable phytopromotional endosymbiont, which mimics the capabilities of AMF. The fungus having a broad host spectrum shows pronounced growth-promotional effects. It mobilizes the insoluble phosphates and translocates the phosphorus to the host in an energy-dependent process. As a biological hardening agent of micropropagat ed plants, it renders more than ninety per cent survival rate for laboratory to field transferred plantlets. The succes sful isolation of regenerative protoplasts of P. indica opens up important possibility of improving symbiosis by transgenic manipulation of fungal component in a symbiosis-specific manner. The immobilization of the fungus stabilizes the infective capacity of the fungus and promises its use as a viable inoculum for biotec hnological applications and long-distance transportation. The axenic cultivability of P. indica on economically viable synthetic media makes it suitable for mass scale inoculum production for application in agro -forestry and horticulture. In sum up, solar energy, water and soil nutrients are undoubtedly essential for plant productivity but the interaction with useful and friendly microbes also exert a tremendous impact. IT is a general belief that plants, because they are aut otrophs, can carry out all the functions of life with the availability of the so -called abiotic factors such as solar energy, moisture and mineral nutrients. However, what is not generally realized is that the plants, as all living o rganisms, also interact with the biotic factors, and their underground root system is under the direct influence of a diverse group of micro-organisms 1 . The mycorrhizal fungi and PGPRs (plant growth promoting rhizobacteria) being mutualistic symbionts, control, in many ways, the plant health 2 . More than 90% of the terrestrial plants (angi osperms, gymnosperms, pteridophytes, bryophytes and some algae) are colonized by mycorrhizal fungi. Arbusc ular mycorrhizal fungi (AMF), which belong to the order Glomales (Zygomycota), are an integral part of the living plant system in a great majority of terrestrial plants. They penetrate into the root cortex of the host and differentiate into special intracel lular structures called arbuscules. These fungi play a pivotal role in plant health, especially in stressed soils which are not normally fertilized and are dependent on rain -fed irrigation 3

Transgenics, pest management, and the environment

Abstract: Genetic engineering of crop plants to confer resistance to insect pests offers an environmental friendly method of crop protection Impressive results have been obtained with the expression of Bacillus thuringiensis (Bt) and other toxin genes in several crops However, both exotic and plant-derived genes have some performance limitations, and there have been some failures in insect control through transgenic crops The production and deployment of transgenic crops for pest control need to address the issues related to impact of the transgenic crops on the insect pests, ecological cost of resistance development, effects on the nontarget organisms, availability and distribution of the alternate host plants, and the potential for introgression of genes into the wild relatives of crops There is a need for a more responsible public debate and better presentation of the benefits for a rational deployment of the geneticallytransformed plants for sustainable crop production

Molecular tools for characterization of rice blast pathogen (Magnaporthe grisea) population and molecular marker-assisted breeding for disease resistance

Abstract: Rice blast caused by the fungal pathogen, Magnaporthe grisea (anamorph: Pyricularia grisea) limits rice yield in all major rice-growing regions of the world, especially in irrigated lands and dry upland environments where predisposition factors favour disease development to epidemic proportions. Deployment of host resistance is by far the most effective means of control. The dynamic evolution of the blast fungus in response to different rice genotypes complicates breeding for blast resistance. In order to prolong the useful life of resistance genes, a knowledge of population genetics and evolutionary biology of the pathogen is r equired. The population structure and virulence composition of the blast fungus have been analysed in terms of genetic diversity, fertility and virulence characteristics. A global atlas of M. grisea and a rice blast database have been constructed based on the information. This report discusses the molecular tools that have been used for characterizing M. grisea populations in epidemic areas and describes how the molecular data generated through these methods are linked to breeding for durable blast resistance. Molecular breeding approach has been deployed in several countries across the world including India for the improvement of blast resistance in high-yielding commercial rice cultivars.

The burden of haemoglobinopathies in India and the challenges ahead.

Abstract: Among the inherited disorders of blood, haemoglobinopathy and thalassaemia constitute a major bulk of noncommunicable genetic diseases in India. They cause a high degree of morbidity, moderate to severe haemolytic anaemia among vulnerable segments of the society like infants and children, adolescent girls, pregnant women, etc. and several deaths in India. It has been estimated that with a population of 1000 million at the new millennium (2000) and a birth rate of 25 per thousand, there would be about 45 million carriers and about 15,000 infants born each year with haemoglobinopathies in India. The carrier frequency of haemoglobinopathy varies between 3 and 17% in different populations of India. The cumulative gene frequency of the three most predominant abnormal haemoglobins, i.e. sickle cell, haemoglobin D and haemoglobin E has been found to be 5.35% in India. This article provides glimpses of haemoglobinopathy and thalassaemia with special emphasis on the epidemiology, diagnosis and clinical profile, and hematological characteristics, distribution and prevalent mutations in India. The current status and challenges of haemoglobinopathies have also been highlighted and discussed with special reference to India.

Diversity of arbuscular mycorrhizal fungi on the coastal sand dunes of the west coast of India

Abstract: We exa mined the diversity of arbuscular mycorrhizal (AM) fungi associated with the dominant strand plant species, Ipomoea pes-caprae of the coastal sand dunes of west coast of India. The study reports the impact of rhizosphere edaphic features and disturbance on the species richness and diversity of AM fungi in 10 geographical locations consisting of moderately disturbed dunes (MDD) and severely disturbed dunes (SDD) during wet and dry seasons. The vegetation cover, AM fungal colonization, species richness and diversity were greater in MDD than in SDD, irrespective of seasons. The AM species richness and spore density of both MDD and SDD were strongly correlated with rhizosphere nitrogen. Among the nine rhizosphere edaphic features, the nitrogen and phosphate showed significant difference between MDD and SDD. Pooled data indicate that Glomus mosseae was most dominant, followed by Glomus dimorphicum, Gigaspora gigantea, Acaulospora taiwania, Glomus fasciculatum and Glomus sp. 27SS. Eleven species scored above 10% frequency on MDD, and it was only three species on SDD. G. mosseae, G. dimorphicum and G. g igantea were most common in both MDD and SDD. The changes in AM fungal community on these sand dunes are in r esponse to distu rbance rather than the reflection on temporal patterns of variation.

Assessment of availability and habitat preference of jatamansi: a critically endangered medicinal plant of west Himalaya.

Abstract: Nardostachys jatamansi (D. Don) DC., a critically endangered rhizome-bearing medicinal plant, is restricted to specialized habitats in high altitudes of the Himalaya, ranging from 3000 to 5000 m asl. The plant is collected from natural habitats for local consumption and trade. The existing status of the species and variations in its performance in different habitats were studied in selected sites in Kumaun, west Himalaya. Dripping moss-laden rocks (frequency 40.7%, density 15.9 individual/m) and moist boulders (frequency 25.9% and density 16.8 individual/m) are the most preferred habitats of this plant. Generally, density and frequency had significant (P < 0.05) positive relationship with altitude. The mean density in two contrasting slopes differed significantly (P < 0.05), showing relatively higher density on west-facing slopes. Several biological and environmental features of the individual plants contributing towards wholesome below-ground biomass were identified. For example, among biological parameters, plant density (P < 0.01), plant height (P < 0.01) and above ground biomass (P < 0.01) were positively correlated. So were soil nitrogen (P < 0.05) and moisture content (P < 0.01) with below ground biomass.

Mapping International Collaboration in Science in Asia through Coauthorship Analysis

Abstract: Using data from SCI 1998, we have analysed inter-national collaboration in science in 11 Asian countries. Papers resulting from collaboration among these countries and with G7, European Union, OECD and selected Latin American and African countries were classified under subject categories to characterize each country’s total and collaborated scientific literature output. Japan (16.4% of internationally collaborated papers), India (17.6%) and Taiwan (1 6.3%) recorded an internationalization index less than 30 whereas China (28.5%), South Korea (24.6%) and Hong Kong 8(36.2%) recorded an internationalization index greater than 40. India, China and South Korea have collab o-rated more in physics, whereas the o ther eight coun-tries have collaborated more in life sciences. In almost all fields and for virtually all Asian countries, USA is the most preferred collaborating partner. All G7 cou n-tries collaborate more with China, which is emerging as a leader in region al collaboration, than with India.

Cancer modulation by glucosinolates: a review.

Abstract: 1. Anastas, P. T. and Warner, G. C., Green Chemistry: Theory and Practice, Oxford University Press, Oxford, 1998. 2. Anastas, P. T. and Williamson, T. C. (eds), Green Chemistry: Frontiers in Benign Chemical Synthesis and Processes, Oxford University Press, Oxford, 1998. 3. Tundo, P. and Anastas, P. T., Green Chemistry: Challenging Perspectives, Oxford University Press, Oxford, 1998. 4. Lee, Y. G. et al., Ind. Eng. Chem. Res., 2000, 39, 2035. 5. Sheldon, R. A., Chem. Rev., 1999, 9, 10. 6. Noyori, R., Chem. Rev., 1999, 99, 353. 7. Morgenstern et al., Green Chemistry (eds Anastas, P. T. and Williamson, T. C.), ACS, Washington DC 1996, pp. 132– 151. 8. Hoelderich, W. F., J. Appl. Catal. A, 2000, 487, 194–195. 9. Johnston, S., Eur. Chem. News, 2000, 72, 32. 10. Sheldon, R. A. et al., Science, 2000, 287, 1636. 11. Haberman, J. X., Irvin, G. C., John, V. T. and Chao-Jun, Li., Green Chem., 1999, 1, 265–267. 12. Yadav, G. D., Pujari, A. A. and Joshi, A. V., Green Chem., 1999, 1, 269. 13. Suib, S. C., Chem. Innovation, 2000, 30, 27. 14. Xiao, J. et al., Chem. Commun., 2000, 839. 15. Choudary, B. M., Catal. Today, 2000, 57, 17. 16. Mishra, S., Curr. Sci., 1998, 75, 1015–1022. 17. Jessop, P. G. and Leitner, W., Chemical Synthesis Using Supercritical Fluids, Wiley-VCH, Weinheim, 1999. 18. King, J. W. and List, G. R. (eds), Supercritical Fluid Technology in Oil and Lipid Chemistry, AOCS Press, Champaign, IL, 1996. 19. Dinjus, E., Fornika, R. and Scholz, M., Chemistry Under Extreme or Non-classical Conditions (eds van Eldik, R. and Hubbard, C. D.), John Wiley, New York, 1997, p. 219. 20. Sanghi, R., Resonance, 2000, 5, 77. 21. Sridar, V., Curr. Sci., 1998, 74, 446. 22. Aguado, J. and Serrano, D., Feedstock Recycling of Plastic Wastes, RSC, 1999. 23. R. Soc. Chem. Newl., July 2000, 6.

RAPD analysis of genetic variability in Indian scented rice germplasm (Oryza sativa L.)

Abstract: CURRENT SCIENCE, VOL. 79, NO. 7, 10 OCTOBER 2000 994 the third position are possibly stabilized due to the multiple turns or proline interactions with solvent or form hydrogen bonds or salt bridge interactions with the rest of the protein atoms. Multiple β-turns with the proline residue in the third position in the first β-turn which corresponds to the proline residue in the second position in an overlapping β-turn were mainly of the type VIa1, VIa2, IV or I.

Recent progress in cotton biotechnology and genetic engineering in China.

Abstract: During the past two decades, China has made great progress in cotton biotechnology and genetic engineering, obtaining first regenerative plants from cotton anther and protoplast culture, and also obtaining regenerative plants from many domestic elite cotton varieties. After transgenic cotton carrying the insect-resistant (Bacillus thuringiensis, Bt) gene was commercialized in 1996, at least ten Bt-cotton varieties were planted in China. In 1998, over 100,000 hectares of Bt-cotton were planted. Two kinds of bivalent insect-resistant transgenic cotton have been obtained. These new bivalent insect-resistant transgenic cotton carried two insecticidal genes, Bt gene and CpTI gene, or pea lectin (P-Lec) gene and soybean Kunitz trypsin inhibitor (SKTI) gene respectively, and will be commercialized in 2000. Herbicide-resistant varieties for 2,4-D and Bromoxynil are under development and are expected to reach the market by 2001 or 2002. Disease-resistant transgenic cotton is being developed and tested in laboratories and fields, and is also expected to reach the market by 2000 or 2001. Fibre improvement, stress resistance, and male sterility and fertility for hybrid cotton are the next targets for cotton biotechnology. Several genes for fibre improvement and hybrid cotton are being tested in various laboratories. New genes for insect, herbicide and disease resistance are being sought.

Whale shark in the Indian coast - Need for conservation

Abstract: Occurrence of whale sharks in India was considered a rarity until recently. Details of whale sharks that have landed so far in the Indian coasts are summarised. The whale shark has become a regular fishery in successive years off Gujarat coast for its meat, fins, liver, skin and cartilage. Over 1000 whale sharks have been hunted off Saurashtra coast during 1998. The present paper gives an account on the year-wise, season-wise, state-wise, depth-wise and gearwise distribution and occurrence of whale sharks, based on incidental landings and capture, in Indian coastal waters from 1889 to 1998. The threat to the whale shark due to commercial exploitation, its utilization and the need for conservation is discussed.

In vitro clonal propagation of annatto (Bixa orellana L.

Abstract: Plants were regenerated from shoot apex and nodal explants on B5 medium supplemented with 1.0 mg/l 2-isopentenyl adenine (2 iP). All the nodal explants gave similar response. However the size of the nodal explant was an important factor in producing multiple shoots – a 0.5 cm long nodal explant produced maximum number of shoots. Regenerated shoots from shoot apex explants rooted best on MS medium supplemented with 0.01 mg/l a-naphthaleneacetic acid (NAA) whereas shoots regenerated from nodal explants needed 0.5 mg/l NAA for rooting. 80% survival of in vivo transferred plants occurred on the best potting substrate, i.e. cocopeat.

Forest dynamics in tropical rain forests of Uttara Kannada district in Western Ghats, India

Abstract: Species richness, tree and stem density, basal area and recruitment details were monitored for ten years (1984 to 1994) in eight one-hectare forest sites in evergreen and moist deciduous forest zones of the tropical rain forests in Uttara Kannada district of the Western Chats in southern India, Changes in species richness and basal area were observed in majority of the forest sites. Loss of more number of stems and trees as well as species was observed in minor forests of the evergreen forest zone. Higher species richness and basal area were observed in reserve forests, perhaps as a result of restricted access. Occurrence of more number of species over ten years In minor forests of moist deciduous zone indicates opening of canopy, favouring growth of other species. Regeneration of existing species in the study plot is suggestive of the site potentiality to retain its physiognomic status. Appearance of species with different physiognomic characters and reduction in basal area suggest greater extraction pressure, implying the deteriorating vegetation status. Increase in the basal area could be due to recruitment, compensatory growth of the existing trees/stems and due to the fast growth of the coppicing trees/stems.