Jawaharlal Nehru University

About: Jawaharlal Nehru University is a education organization based out in New Delhi, India. It is known for research contribution in the topics: Population & Candida albicans. The organization has 6082 authors who have published 13455 publications receiving 245407 citations. The organization is also known as: JNU.

A mechanistic analysis of the increase in the thermal stability of proteins in aqueous carboxylic acid salt solutions

Abstract: The stability of proteins is known to be affected significantly in the presence of high concentration of salts and is highly pH dependent. Extensive studies have been carried out on the stability of proteins in the presence of simple electrolytes and evaluated in terms of preferential interactions and increase in the surface tension of the medium. We have carried out an in-depth study of the effects of a series of carboxylic acid salts: ethylene diamine tetra acetate, butane tetra carboxylate, propane tricarballylate, citrate, succinate, tartarate, malonate, and gluconate on the thermal stability of five different proteins that vary in their physico-chemical properties: RNase A, cytochrome c, trypsin inhibitor, myoglobin, and lysozyme. Surface tension measurements of aqueous solutions of the salts indicate an increase in the surface tension of the medium that is very strongly correlated with the increase in the thermal stability of proteins. There is also a linear correlation of the increase in thermal stability with the number of carboxylic groups in the salt. Thermal stability has been found to increase by as much as 22 C at 1 M concentration of salt. Such a high thermal stability at identical concentrations has not been reported before. The differences in the heat capacities of denaturation, deltaCp for RNase A, deduced from the transition curves obtained in the presence of varying concentrations of GdmCl and that of carboxylic acid salts as a function of pH, indicate that the nature of the solvent medium and its interactions with the two end states of the protein control the thermodynamics of protein denaturation. Among the physico-chemical properties of proteins, there seems to be an interplay of the hydrophobic and electrostatic interactions that lead to an overall stabilizing effect. Increase in surface free energy of the solvent medium upon addition of the carboxylic acid salts appears to be the dominant factor in governing the thermal stability of proteins.

Remodeling of the malaria parasite and host human red cell by vesicle amplification that induces artemisinin resistance

Abstract: Artemisinin resistance threatens worldwide malaria control and elimination. Elevation of phosphatidylinositol-3-phosphate (PI3P) can induce resistance in blood stages of Plasmodium falciparum The parasite unfolded protein response (UPR) has also been implicated as a proteostatic mechanism that may diminish artemisinin-induced toxic proteopathy. How PI3P acts and its connection to the UPR remain unknown, although both are conferred by mutation in P falciparum Kelch13 (K13), the marker of artemisinin resistance. Here we used cryoimmunoelectron microscopy to show that K13 concentrates at PI3P tubules/vesicles of the parasite's endoplasmic reticulum (ER) in infected red cells. K13 colocalizes and copurifies with the major virulence adhesin PfEMP1. The PfEMP1-K13 proteome is comprehensively enriched in multiple proteostasis systems of protein export, quality control, and folding in the ER and cytoplasm and UPR. Synthetic elevation of PI3P that induces resistance in absence of K13 mutation also yields signatures of proteostasis and clinical resistance. These findings imply a key role for PI3P-vesicle amplification as a mechanism of resistance of infected red cells. As validation, the major resistance mutation K13C580Y quantitatively increased PI3P tubules/vesicles, exporting them throughout the parasite and the red cell. Chemical inhibitors and fluorescence microscopy showed that alterations in PfEMP1 export to the red cell and cytoadherence of infected cells to a host endothelial receptor are features of multiple K13 mutants. Together these data suggest that amplified PI3P vesicles disseminate widespread proteostatic capacity that may neutralize artemisinins toxic proteopathy and implicate a role for the host red cell in artemisinin resistance. The mechanistic insights generated will have an impact on malaria drug development.

Decision tree classification of land use land cover for Delhi, India using IRS-P6 AWiFS data

Abstract: Research highlights? We explored the potential of multi-temporal IRS P6 (Resourcesat) Advanced Wide Field Sensor (AWiFS) data for mapping of LULC for Delhi, India. ? A decision tree classification of seasonal composite (three seasons) temporal data set with a good definition of training sites was presented. ? We mapped eight different LULC classes with overall classification accuracy 89%. ? The database is first of its kind being a product of moderate to high resolution (=56m) multi-temporal satellite data. ? We recommend the use of AWiFS data for LULC mapping for regional level assessment and monitoring. In this study we explored the potential of multi-temporal IRS P6 (Resourcesat) Advanced Wide Field Sensor (AWiFS) data for mapping of LULC for Delhi, India. The study presents the result of a decision tree classification of seasonal composite data (three seasons). The study has identified 13 classes with description of cropping pattern namely, double crops, kharif, rabi and zaid from 56m spatial resolution AWiFS data. Delhi has a diverse range of land use predominantly mosaic of built-up. More than half of the area is urban settlement. Results indicate that the temporal data set with a good definition of training sites can result in good overall accuracy (=91.81) as well as individual classification accuracies (producers accuracy ?76.92 and users accuracy ?60). It is evident that AWiFS data can be used to provide timely and detailed LULC maps with limited ancillary data. The AWiFS derived maps could be very useful as input to biogeochemical models that require timely estimation of LULC patterns.

Stable phase-locking of an external-cavity diode laser subjected to external optical injection

Abstract: We analyse the locking phenomena arising when an external-cavity diode laser is subjected to optical injection from another uncontrolled diode laser. The system stability is investigated as a function of coupled cavity time delay and the optical injection strength. Different regimes, spanning from 'in-phase locking' to 'out-of-phase locking' with ultimate amplitude death of low-frequency fluctuations/pulsations, are described experimentally as well as numerically for weak to moderate injection. Qualitative agreements between numerically and experimentally observed results for amplitude quenching are shown. Numerical studies describe the shifting of phase-flip bifurcation as the optical injection strength is varied for a particular time delay. Stable phase-locking behaviours, which are desired from the point of view of practical applications, are observed numerically in a wide range of control parameter space.

Rare earth elements and heavy metal distribution in estuarine sediments of east coast of India

Abstract: Bed sediment samples collected from the Hoogly, Godavari, Krishna and Cauvery estuaries on the east coast of India were analyzed for rare earth elements (REEs), mainly lanthanides (La‐Lu), Y, a number of metals (V, Cr, Co, Ni, Zn, Ag, Cd and Pb), using Thermal Ionization Mass Spectrometry. Continental weathering plays an important role in the distribution of REEs and metals. However, metals showed wide variation in concentration among estuaries, mainly due to varying salinity, which controls complex estuarine processes, and partly to anthropogenic inputs. Factor analysis of elemental data identified two major groups of elements: (i) LREEs, HREEs, Cd, Pb and Ag, revealing an association with detritals brought in by the rivers; and (ii) V, Cr , Co, Ni and Zn, indicating complex estuarine processes and human input. LREEs are more enriched than HREEs (LREE/HREE ratio varied between 12 and 40) reflecting silicate weathering of crustal materials, and a resultant increase in LREEs in detritals. We conclude that the estuarine system constitutes 70% of LREEs and 30% of HREE flux to the Bay of Bengal.