Search Results - (Author, Cooperation:A. K. Kashyap)

2012-09-18

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Antibodies, Neutralizing/*chemistry/genetics/*immunology ; Antibodies, Viral/*chemistry/genetics/*immunology ; Antibody Specificity/genetics/*immunology ; Antigens, Viral/chemistry/immunology ; Binding Sites ; Complementarity Determining Regions/chemistry/genetics/immunology ; Conserved Sequence ; Cross Reactions/genetics/immunology ; Crystallography, X-Ray ; Enzyme-Linked Immunosorbent Assay ; Epitopes/chemistry/immunology ; Hemagglutinin Glycoproteins, Influenza Virus/chemistry/immunology ; Influenza A Virus, H1N1 Subtype/chemistry/immunology ; Influenza A Virus, H3N2 Subtype/chemistry/immunology ; Influenza A virus/chemistry/*classification/*immunology ; Influenza Vaccines/immunology ; Mice ; Models, Molecular ; Molecular Sequence Data ; Mutation/genetics ; Orthomyxoviridae Infections/immunology/prevention & control/virology ; Protein Conformation

Euro. ; Monetary policy, European Union countries. ; Transmission mechanism (Monetary policy)

xv, 497 p.

0-511-06283-4

Banks and banking, Japan, History. ; Corporate governance, Japan, History. ; Corporations, Japan, Finance, History. ; Finance, Japan, History.

xx, 358 p.

0-585-44589-3

1432-1904

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Natural Sciences in General

Electronic Resource

1617-4623

Springer Online Journal Archives 1860-2000

Biology

Summary Ammonium (NH 4 + ) transport was investigated in Nostoc muscorum ISU (wild type) and spontaneous mutants resistant to cyanophage N-1 (Nm/N-1), streptomycin (Nm/Sm) and methylamine (Nm/MA). N2-fixing wild-type cells transported NH 4 + via two transport systems: the ‘high-affinity’ (K m 11 μM) and ‘low-affinity’ (K m 66 μM), which formed 10 and 50-fold concentration gradients, respectively. The high-affinity system of Nm/MA (K m 11 μM) was similar to the wild type but the low-affinity system had reduced affinity for NH 4 + (K m 125 μM), while Nm/N-1 and Nm/Sm mutants had only a high-affinity transport system (K m 20 and 28 μM, respectively). The growth of mutant Nm/N-1 was more sensitive to 1 mM NH 4 + or methylamine than other strains, and also glutamine-synthetase activity was most reduced in NH 4 + -grown cells. l-methionine-d, l-sulfoximine (20 μM) treatment of N2-grown Nm/N-1 cells resulted in a higher rate of NH 4 + efflux. The apparent alterations in kinetic constants of NH 4 + transport in mutants and glutamine synthetase activity suggested that NH 4 + in N. muscorum is transported by specific carrier(s) and the transport is genetically controlled.

Electronic Resource

1573-5117

nutrients ; algae ; cyanobacteria ; streams ; Antarctica

Springer Online Journal Archives 1860-2000

Biology

Abstract The algal and cyanobacterial flora and the chemical environment of six freshwater streams of Schirmacher Oasis, Antarctica were investigated. Over 30 species of algae, predominantly cyanobacteria (Cyanophyceae), were recorded. N2-fixing species, both heterocystous and unicellular diazotrophs, contributed more than 50% to the counts and their dominance was greatest in the middle of the stream where nitrogen and other nutrients were low. Green algae and diatoms also contributed to the flora. The species composition varied between streams. Glacial and snow drift meltwater streams contained a distinctive community. Based on diversity indices, these streams could be classified into two clusters.

Electronic Resource

1617-4623

Anabaena doliolum ; Sporulation ; Mutants ; Nitrogen fixation ; Cell constituents

Springer Online Journal Archives 1860-2000

Biology

Summary Mutants of Anabaena doliolum (AdS strain) altered with respect to the time of initiation and degree of sporulation were isolated following mutagenesis with N-methyl-N′-nitro-N-nitrosoguanidine and hydroxylamine. The non-sporulating mutant showed a high phycocyanin (Pc): chlorophyll a (chl a) ratio (ca. 7.2) as compared to sporulating strains (Pc:chl a, 4.7–5.3). Also this strain seemed to have higher RNA pools per unit of genomic material as reflected in a higher RNA:DNA ratio. The data suggest that degradaton of phycocyanin and controlled RNA synthesis are prerequisites for sporulation. Mutants exhibiting non-sporulation and delayed initiation of sporulation accumulated more nitrogen through nitrogen fixation, probably indicating nitrogenase function over an extended vegetative phase.

Electronic Resource

1573-5036

clay content ; forest ; N-mineralization ; ammonia-and nitrite-oxidizing bacteria ; soil moisture

Springer Online Journal Archives 1860-2000

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Abstract Seasonal dynamics of N-mineralization and the size of the viable community of nitrifying bacteria were studied for a forest site and an adjoining cropland site. The forest site was dominated by Boswellia serrata and Acacia catechu in the tree layer, and by Nyctanthes arbortristis and Zizyphus glaberrima in the shrub layer. Crop sequence on the cropland site was Oryza sativa/Lens culinaris. The soil type in both the sites was ultisol (USDA). The cropland soil had significantly higher bulk density, and clay content but lower organic C, total N and total P than forest soil. The soil moisture content, numbers of ammonia-and nitrite oxidizing bacteria and N-mineralization rates were highest in the wet season and lowest in the dry season, while the size of mineral N and P pools showed a reverse trend in both sites. The numbers of free-living cells of ammonia-and nitrite oxidizing bacteria were significantly related with each other as well as with the soil moisture content and N-mineralization rates. In N-mineralization, NO 3 − was the dominating form in the forest site during rainy season, while in other seasons in this site and in all the seasons in the cropland site, NH 4 + -N was predominant. The N-mineralization rate and the number of viable nitrifying cells were consistently higher for the forest soil compared to the clay-rich cropland soil. The combination of low soil organic matter and high clay content suppressed the number of free-living cells of nitrifying bacteria and N-mineralization rates in the cropland site.

Electronic Resource

1573-5036

agroecosystem ; fertilizer treatment ; methane flux ; phenology ; water level

Springer Online Journal Archives 1860-2000

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Abstract Methane flux was measured for a rice/wheat agroecosystem of Gangetic Plains, with and without application of chemical fertilizer and wheat straw (WS). Three treatments of control, fertilizer application and fertilizer + WS application, were established in a completely randomized block design and measurements were made for two consecutive years (1993 and 1994). CH4 measurements during growth of the rice crop period showed that there were significant difference in flux rates during the two years. Maximum emission occurred at the time of anthesis and minimum at the seedling stage. The flux rates were significantly higher for fertilizer or fertilizer + WS treatments. The effects of the treatments were similar across phenological stages and years. In the subsequent wheat crop and fallow period, the soils consumed CH4. There were significant differences in CH4 uptake rates between the two years. Fertilizer treatments reduced CH4 uptake in both the years. The results suggested that tropical agroecosystems may consume substantial amounts of CH4 and that the methane output can be reduced by lowering the submergence level in rice paddies.

Electronic Resource

1573-6776

Springer Online Journal Archives 1860-2000

Process Engineering, Biotechnology, Nutrition Technology

Summary Nitrogen fixing cultures of the cyanobacteriumNostoc muscorum lacked hydrogen evolution but cultures infected with cyanophage N-1 showed significant hydrogen evolution and inactive nitrogenase, suggesting that nitrogenase activity is not responsible for the observed oxygen-resistant photoproduction of hydrogen. Significant oxygen-resistant hydrogen production by nitrate or ammonium assimilating cultures deficient in both nitrogenase and uptake hydrogenase activity supports this conclusion. These findings suggest a role of uptake hydrogenase in blocking the production of hydrogen during aerobic photosynthetic conditions.

Electronic Resource

0025-116X

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Physics

The Stockmayer-Fixman relation was used to evaluate the short range and long range interaction parameters for methyl methacrylate/acrylonitrile copolymers of 0,566 and 0,657 mole fraction of monomeric units of acrylonitrile in the solvents acetonitrile, 2-butanone, dimethyl formamide, and γ-butyrolactone, at different temperatures (30, 45, and 60°C). The values of K0 were found to be lower than those of the parent homopolymers, and their values depend on both solvent and temperature. Even negative K0-values were obtained, in cases in which the Mark Houwink exponent a is nearly unity. The values of the polymer-solvent interaction parameter, χ1, are high and close to 0,5, indicating that these solvents are not good. The values of the excess interaction parameter, χAB, are negative and are not affected by temperature. The large extension of these copolymer chains, as exhibited by a and αη3-values, can be understood in terms of unusual short range interactions only. Similar results were obtained for some cellulose derivatives.

2 Ill.

Electronic Resource

0025-116X

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Physics

Studies on the dilute solution properties of methyl methacrylate/acrylonitrile random copolymers of 0,566 mole fraction (m. f.) of acrylonitrile (AN), designated as MA3 and of 0,657 m. f. of AN, designated as MA4 reveal that the Mark-Houwink exponent values a for MA3 lie in the range 0,6 to 0,8 and for MA4 in the range 0,8 to 1,1 in the solvents studied, viz. acetonitrile (MeCN), 2-butanone (MEK), N,N-dimethylformamide (DMF) and γ-butyrolactone (γ-BL) at the temperatures 30°C, 45°C and 60°C. Such large values of a suggest that these copolymer chains are highly extended in these solvents. The decrease of [η] with an increase in temperature also supports the above conclusion that these are very good solvents.

6 Ill.

Electronic Resource

1432-0991

Springer Online Journal Archives 1860-2000

Biology

Medicine

Abstract Cyanophage N-1-infectedNostoc muscorum cells were unable to carry out oxygen evolution and photosystem-II-dependent electron transport (H2O→DCPIP). This was associated with preferential degradation of phycobiliproteins. Such cells also exhibited decreased rate of ferredoxin:NADP+ oxidoreductase activity. However, Ca2+-dependent ATPase activity was maintained at a higher level (80%). The results suggested that virus development proceeds in the absence of photosystem-II activity, and the energy is provided by cyclic photophosphorylation aside from that possibly obtained via degradation of carbohydrate reserves.

Electronic Resource

0360-6376

Physics ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

This article deals with studies of the dilute solution properties of methyl methacrylate-acrylonitrile (MMA-AN) copolymer of 0.415 mole fraction (mf) of acrylonitrile composition. Mark - Houwink parameters for this copolymer have been evaluated in acetonitrile (MeCN), 2-butanone (MEK), dimethyl formamide (DMF), and γ-butyrolactone (γ-BL). The Mark-Houwink exponent a in all four solvents at all temperatures is larger than the corresponding values of the parent homopolymers. The solvent power is in the order of DMF 〈 γ-BL 〈 MEK 〈 MeCN; [η] decreases with an increase in temperature, which is behavior characteristic of polymers in good solvent. The unperturbed dimensions (K0) values, obtained by the Stockmayer-Fixman method, are lower than those for the parent homopolymers and depend on solvent as well as temperature. The solute - solvent interaction parameter X1 values are close to 0.5; X1 is independent of temperature. The excess interaction parameter XABvalues are negative. The results for this copolymer system in regard to low second virial coefficient A2, large X1, and high a values suggest that the large extension of these copolymer chains is due to the unusual short-range interactions.

4 Ill.

Electronic Resource