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.

A unique Ni2+ ‐dependent and methylglyoxal‐inducible rice glyoxalase I possesses a single active site and functions in abiotic stress response

Abstract: †Both authors contributed equally to this work. SUMMARY The glyoxalase system constitutes the major pathway for the detoxification of metabolically produced cytotoxin methylglyoxal (MG) into a non-toxic metabolite D-lactate. Glyoxalase I (GLY I) is an evolutionarily conserved metalloenzyme requiring divalent metal ions for its activity: Zn 2+ in the case of eukaryotes or Ni 2+ for enzymes of prokaryotic origin. Plant GLY I proteins are part of a multimember family; however, not much is known about their physiological function, structure and metal dependency. In this study, we report a unique GLY I (OsGLYI-11.2) from Oryza sativa (rice) that requires Ni 2+ for its activity. Its biochemical, structural and functional characterization revealed it to be a monomeric enzyme, possessing a single Ni 2+ coordination site despite containing two GLY I domains. The requirement of Ni 2+ as a cofactor by an enzyme involved in cellular detoxification suggests an essential role for this otherwise toxic heavy metal in the stress response. Intriguingly, the expression of OsGLYI-11.2 was found to be highly substrate inducible, suggesting an important mode of regulation for its cellular levels. Heterologous expression of OsGLYI-11.2 in Escherichia coli and model plant Nicotiana tabacum (tobacco) resulted in improved adaptation to various abiotic stresses caused by increased scavenging of MG, lower Na + /K + ratio and maintenance of reduced glutathione levels. Together, our results suggest interesting links between MG cellular levels, its detoxification by GLY I, and Ni 2+ – the heavy metal cofactor of OsGLYI-11.2, in relation to stress response and adaptation in plants.

An efficient leaf-disc culture method for the regeneration via somatic embryogenesis and transformation of grape (Vitis vinifera L.)

Abstract: By manipulating hormone levels, light intensities and temperature, we have developed an efficient leaf-disc method for the regeneration of plants via embryogenesis and for transformation in four genotypes of Vitis viniferaL. In MS basal medium supplemented with 1 mg l–16-benzylaminopurine (BAP) and 0.1 mg l–12,4-dichlorophenoxyacetic acid, leaf discs cultured for 2 weeks under dark conditions produced calli in over 80% of the cultures. These subsequently differentiated into pro-embryos and embryos only if kept under conditions of low light intensity (15 µE m–2 s–1) for 2 weeks before being transferred to conditions of high light intensity (60 µE m–2 s–1). If the calli were directly transferred to high light intensity, the differentiation into embryos was blocked and the calli turned pink. The somatic embryos germinated at a frequency of about 10% on NN basal medium and about 32% on NN medium supplemented with 1 mg l–1BAP and 0.1 mg l–1indole-3-butyric acid. The embryos, however, germinated when pre-exposed to a low temperature of 4°C for 2 weeks. If they were transferred directly to room temperature under conditions of high light intensity (60 µE m–2 s–1), shoot buds were produced, whereas under conditions of low light intensity (15 µE m–2 s–1) secondary embryogenesis was induced. About 90–95% of the in vitro grown plantlets could be successfully transferred to soil. The above method was also applicable for developing transgenic embryos whose transgenic nature was monitored using β-glucuronidase as a reporter gene.

Evidence for presence of hyaluronan binding protein on spermatozoa and its possible involvement in sperm function.

Abstract: Hyaluronic acid, a major component of the extracellular matrix, plays an important role in the regulation of different cellular processes, e.g., locomotion, cell-cell interaction during morphogenesis, and differentiation. Distribution of hyaluronic acid with respect to the role of sperm hyaluronidase in sperm penetration and gamete interaction is well established. In order to elucidate this mechanism, in our current study we have identified and demonstrated, for the first time, the presence of a 68-kDa cell surface hyaluronic acid binding glycoprotein (HABP) in spermatozoa of different species (rat, mice, bull, and human) by immunoblot analysis and indirect immunofluorescence using the polyclonal antibodies raised against purified HABP. Furthermore, we were able to demonstrate a differential distribution of 68-kDa HA binding protein on the sperm head, midpiece, and tail of different species. To identify its role in sperm function, we observed its declining pattern during epididymal maturation and also the inhibition of sperm-oolemmal adherence by pretreatment of the sperms with anti-HABP antibodies. We have further observed its in vivo phosphorylation in motile spermatozoa. All our data clearly indicate that sperm hyaluronan binding protein may have a specific role in sperm maturation, motility, and fertilization processes.

Pb and Nd isotope constraints on the origin of high Mg and tholeiitic amphibolites, Kolar Schist Belt, South India

Abstract: The late Archean, north-south trending Kolar Schist Belt in south India, 4 km wide by 80 km long, is thought to be a suture between two gneiss terranes (Krogstad et al. 1989). Within this volcanics-dominated belt are recognized both tholeiitic and high Mg (komatiitic and picritic) amphibolites, which make up some 70% and 5% respectively of the exposed outcrops. A massive tholeiitic amphibolite separates the belt into western and eastern parts. A Pb-Pb whole-rock age of 2732±155 Ma on samples from a single outcrop of massive tholeiite is a minimum age for this rock. Samples of this rock have ɛNd values at 2700 Ma that range between +3.8 and +6.8, μ1 (initial 238U/204Pb) of 7.5 and K1 (initial 232Th/238U) of about 4. Two different types of high-Mg amphibolites are recognized from the western part of the belt: a picritic or P-type, and a komatiitic or K-type. The P-type have highly variable Ce/Al ratios all greater than chondritic, Nd/Yb ratios greater than chondritic, ɛNd at 2700 Ma of +1.5 to +8, and Pb isotope compositions variable in 207Pb/204Pb with μ1 of about 8.0 and k1 of about 4. The trace-element data suggest that the light-REE enrichment is a character of the mantle source and is not due to residual garnet. The K-type amphibolites have near chondritic Ce/Al and Nd/Yb ratios, ɛNd at 2700 Ma of +1.5 to +8, and μ1 of about 8 and k1 of about 4. Although the P-type is light-REE enriched compared to the K-type, both types have similar Ce/Nd ratios as well as initial Pb and Nd isotopes. If the 2696±136 Ma age for the Sm-Nd isochron which includes both types of high-Mg amphibolite has any significance it dates the time of light-REE enrichment of the mantle source for the P-type komatiitic amphibolites. The high-Mg amphibolites in the eastern part of the belt are light-REE enriched, have Pb isotopic compositions that are variable in 207Pb/204Pb with a μ1 about 8.5 and ɛNd at 2700 Ma of +1.8 to +4.5. Hydrothermal fluids associated with metamorphism and shearing prior to about 2400 Ma ago were responsible for the introduction of gold-quartz-carbonate veins into the Kolar Schist Belt. The Pb isotope composition of galena in these veins suggests that these fluids may have also introduced extraneous Pb from adjacent older granitoid gneisses into the amphibolites, which could be responsible for the variability in the 207Pb/204Pb ratios of the samples. This extraneous Pb probably is not responsible for the distinct Pb isotope character of each type of amphibolite.