Phosphate solubilization and growth promotion by <Emphasis Type="Italic">Pseudomonas fragi</Emphasis> CS11RH1 (MTCC 8984), a psychrotolerant bacterium isolated from a high altitude Himalayan rhizosphere

Phosphate solubilization and growth promotion by Pseudomonas fragi CS11RH1 (MTCC 8984), a psychrotolerant bacterium isolated from a high altitude garlic rhizosphere from the Indian Himalayas, are reported here. The identity of the isolate was arrived on the basis of its biochemical features and sequencing of the 16S rRNA gene. The isolate grew and solubilized phosphate at temperatures ranging from 4 to 30°C. Besides solubilizing P it produced indole acetic acid (IAA) and hydrogen cyanide (HCN). Seed bacterization with the isolate significantly increased the percent germination, rate of germination, plant biomass and nutrient uptake of wheat seedlings. While Pseudomonas fragi is normally associated with the spoilage of dairy products stored at cold temperatures, this is an early report on the plant growth promoting ability of the bacterium.     

Oxidation of methionine residues in recombinant human interleukin-1 receptor antagonist: implications of conformational stability on protein oxidation kinetics

Oxidation of methionine residues is involved in several biochemical processes and in degradation of therapeutic proteins. The relationship between conformational stability and methionine oxidation in recombinant human interleukin-1 receptor antagonist (rhIL-1ra) was investigated to document how thermodynamics of unfolding affect methionine oxidation in proteins. Conformational stability of rhIL-1ra was monitored by equilibrium urea denaturation, and thermodynamic parameters of unfolding (DeltaGH2O, m, and Cm) were estimated at different temperatures. Methionine oxidation induced by hydrogen peroxide at varying temperatures was monitored during "coincubation" of rhIL-1ra with peptides mimicking specific regions of the reactive methionine residues in the protein. The coincubation study allowed estimation of oxidation rates in protein and peptide at each temperature from which normalized oxidation rate constants and activation energies were calculated. The rate constants for buried Met-11 in the protein were lower than for methionine in the peptide with an associated increase in activation energy. The rate constants and activation energy of solvent exposed methionines in protein and peptide were similar. The results showed that conformational stability, monitored using the Cm value, has an effect on oxidation rates of buried methionines. The rate constant of buried Met-11 correlated well with the Cm value but not DeltaGH2O. No correlation was observed for the oxidation rates of solvent-exposed methionines with any thermodynamic parameters of unfolding. The findings presented have implications in protein engineering, in design of accelerated stability studies for protein formulation development, and in understanding disease conditions involving protein oxidation.     

Site of cholesterol absorption in some insects

The principal site of cholesterol absorption was studied in a number of insects using ³H-cholesterol mixed with the diet of the insects. In omnivorous insects (Gryllodes sigilatus and Camponotus compressus) and a carnivorous insect (Dytiscus sp.) cholesterol was absorbed in the foregut, predominantly in the crop. In the phytophagus insects and some others (Schistocerca gregaria, Hieroglyphus nigrorepletus, Dysdercus koenigii, Belostoma sp., Lucilia sp., Apis sp. Mylabris phalerata and larvae of Papilio demoleus, Prodenia litura, and Earias fabia) the midgut was the main site of cholesterol absorption.     

Quantitation of platelet adhesion to Ti and DLC-coated Ti in vitro using (125)I-labeled platelets

Measurement of platelet adhesion in vitro is a good indicator of its reactivity to implant devices in vivo. Platelets were labeled with I-125 without affecting its normal morphology and function and the labeled platelets were suspended in platelet poor plasma and exposed to Ti and diamond like carbon-coated (DLC) Ti discs, under dynamic conditions, using a parallel plate flow chamber. The test materials were washed, dried, exposed to a phosphor screen and scanned to get the images. The number of platelets that adhered to Ti was found to be higher than those that adhered to DLC coated Ti sample, irrespective of the shear stress which was varied between 2 and 16 dynes/cm(2).     

GANDivAWeb: A web server for detecting early folding units ("foldons") from protein 3D structures

Background  

It has long been known that small regions of proteins tend to fold independently and are then stabilized by interactions between these distinct subunits or modules. Such units, also known as autonomous folding units (AFUs) or"foldons" play a key role in protein folding. A knowledge of such early folding units has diverse applications in protein engineering as well as in developing an understanding of the protein folding process. Such AFUs can also be used as model systems in order to study the structural organization of proteins.     

Optimal Regulation of Gas Exchange: Evidence from Field Data

Since the work of Cowan in 1977 it has been assumed that plantsregulate their stomata in a way that maximizes photosynthesisat a constant average rate of transpiration. The approach wasfurther developed by Hari et al. (1986) by introducing additionalassumptions which enabled the mathematical solution of the optimizationproblem using the Lagrangian method. The solution is testedfor Scots pine seedlings against field data. The results supportthe optimization hypothesis.Copyright 1993, 1999 Academic Press Pinus sylvestris (L.), stomatal conductance, photosynthesis, transpiration, optimization, field measurements, mathematical model, Lagrangian method