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 & Politics. The organization has 6082 authors who have published 13455 publications receiving 245407 citations. The organization is also known as: JNU.

Magnetism driven ferroelectricity above liquid nitrogen temperature in Y2CoMnO6

Abstract: We report multiferroic behaviour in double perovskite Y2CoMnO6 with ferroelectric transition temperature Tc = 80 K. Both X-ray diffraction and neutron scattering data confirm a centro-symmetric crystal structure of space group P21/n at room temperature. The saturation polarization and magnetization are estimated to be 65 μC/m2 and 6.2 μB/f.u. respectively. The magneto-electric coupling parameter, on the other hand, is small as a 5 T field suppresses the electric polarization by only ∼8%. The origin of ferroelectricity is associated with magnetic ordering of Co2+ and Mn4+ moments in ↑↑-↓↓ arrangement. A model based on exchange-striction is proposed to explain the observed high temperature ferroelectricity.

Nucleotide homology and organization of chlorocatechol oxidation genes of plasmids pJP4 and pAC27.

Abstract: The 2,4-dichlorophenoxyacetate (2,4-D) catabolic plasmid pJP4 of Alcaligenes eutrophus JMP134 contains two sets of nonidentical chlorocatechol oxidation gene sequences physically separated by a 7 kb DNA region. We determined the nucleotide sequence of the 1.6 kb HindIII fragment containing the known genes tfdC and tfdD (Don et al. 1985) which encode pyrocatechase and cycloisomerase, respectively. The 1.3 kb BglII-HindIII segment of recombinant plasmid pDC25 containing at least three chlorocatechol (clc) oxidation genes of the pAC27 plasmid in Pseudomonas putida AC868 (Ghosal et al. 1985a; Frantz and Chakrabarty 1986), was also sequenced. When the tfdC gene of the pJP4 plasmid was compared with gene clcA of plasmid pAC27, which encodes the chlorocatechol specific pyrocatechase (pyrocatechase II), the two genes showed 63% nucleotide sequence homology with 60% homology in their amino acid sequences. In both plasmid pJP4 and pAC27, the two genes encoding the pyrocatechase and the cycloisomerase showed a 4 bp overlap spanning the initiation codon of the cycloisomerase gene and the termination codon of the pyrocatechase gene. The sizes of the polypeptides encoded by the isofunctional genes tfdC and clcA are very similar and thus reflect their functional homology.

Overexpression of rice CBS domain containing protein improves salinity, oxidative, and heavy metal tolerance in transgenic tobacco.

Abstract: We have recently identified and classified a cystathionine β-synthase domain containing protein family in Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa L.). Based on the microarray and MPSS data, we have suggested their involvement in stress tolerance. In this study, we have characterized a rice protein of unknown function, OsCBSX4. This gene was found to be upregulated under high salinity, heavy metal, and oxidative stresses at seedling stage. Transgenic tobacco plants overexpressing OsCBSX4 exhibited improved tolerance toward salinity, heavy metal, and oxidative stress. This enhanced stress tolerance in transgenic plants could directly be correlated with higher accumulation of OsCBSX4 protein. Transgenic plants could grow and set seeds under continuous presence of 150 mM NaCl. The total seed yield in WT plants was reduced by 80%, while in transgenic plants, it was reduced only by 15-17%. The transgenic plants accumulated less Na+, especially in seeds and maintained higher net photosynthesis rate and Fv/Fm than WT plants under NaCl stress. Transgenic seedlings also accumulated significantly less H2O2 as compared to WT under salinity, heavy metal, and oxidative stress. OsCBSX4 overexpressing transgenic plants exhibit higher abiotic stress tolerance than WT plants suggesting its role in abiotic stress tolerance in plants.

Protein Kinases and Phosphatases and Their Role in Cellular Signaling in Plants

Abstract: Plants respond very efficiently to changes in the external environment and accordingly regulate their growth and development. They also have the ability to sense stress conditions and pathogen presence and subsequently activate stress or defense-related functions. Lately, progress has been made in identification of cis- and trans-acting factors that mediate gene expression induced by variable external factors. However, in most of the cases our understanding is limited in relation to the molecular signal transduction events that couple perception of the signal and changes in the gene expression. It is now realized that protein phosphorylation/dephosphorylation has a very important role in signal transduction and also in regulating metabolic activities. During the last decade, a large number of serine/threonine protein kinases have been isolated from plants. Some of these belong to the same category as reported in animal systems, like MAP kinases, receptor kinases, cell division controlling kinases, whereas...