North Eastern Hill University

About: North Eastern Hill University is a education organization based out in Shillong, Meghalaya, India. It is known for research contribution in the topics: Population & Catalysis. The organization has 2318 authors who have published 4476 publications receiving 48894 citations.

Carbamyl Phosphate Synthetases in an Air-Breathing Teleost, Heteropneustes fossilis

Abstract: The Indian air-breathing teleost fish Heteropneustes fossilis has been shown to have a functional urea cycle and to be able to switch from ammoniotelic to ureotelic nitrogen metabolism when exposed to high levels of ammonia or air. The objective of this study was to identify the type of carbamyl phosphate synthetase (CPS) catalyzing the first step of the urea cycle in H. fossilis . Mitochondrial CPS III [glutamine- and N-acetyl-L-glutamate (NAG)-dependent] and cytosolic CPS II (glutamine-dependent) activities were found to be present in liver, analogous to that described for two other teleosts that have CPS III activity. The same activities and subcellar localization were found in kidney. Unexpectedly, a CPS I-like activity (ammonia- and NAG-dependent) was found to be present at levels higher than the CPS III activity in the mitochondrial fraction of both liver and kidney. The urea cycle-related CPS III found in invertebrates and fish is considered to be the evolutionary precursor of the urea cycle-related CPS I in ureotelic mammalian and amphibian species. Whether or not this CPS I-like activity 1) is due to the presence of a separate CPS I gene in addition to a CPS III gene or 2) represents an adapted CPS III activity in H. fossilis , these results suggest that the presence of both CPS I-like and CPS III activities may play an important physiological adaptive role in the tolerance of these fish to high concentrations of external ammonia.

Cultivable bacterial diversity along the altitudinal zonation and vegetation range of tropical Eastern Himalaya

Abstract: The Northeastern part of India sprawls over an area of 262 379km2 in the Eastern Himalayan range. This constitutes a biodiversity hotspot with high levels of biodiversity and endemism; unfortunately, is also a poorly known area, especially on its microbial diversity. In this study, we assessed cultivable soil bacterial diversity and distribution from lowlands to highlands (34 to 3 990m.a.s.l.). Soil physico-chemical parameters and forest types across the different altitudes were characterized and correlated with bacterial distribution and diversity. Microbes from the soil samples were grown in Nutrient, Muller Hinton and Luria-Bertani agar plates and were initially characterized using biochemical methods. Parameters like dehydrogenase and urease activities, temperature, moisture content, pH, carbon content, bulk density of the sampled soil were measured for each site. Representative isolates were also subjected to 16S rDNA sequence analysis. A total of 155 cultivable bacterial isolates were characterized which were analyzed for richness, evenness and diversity indices. The tropical and sub-tropical forests supported higher bacterial diversity compared to temperate pine, temperate conifer, and sub-alpine rhododendron forests. The 16S rRNA phylogenetic analysis revealed that Firmicutes was the most common group followed by Proteobacteria and Bacteroidetes. Species belonging to the genera Bacillus and Pseudomonas were the most abundant. Bacterial CFU showed positive but insignificant correlation with soil parameters like pH (r=0.208), soil temperature (r=0.303), ambient temperature (r=0.443), soil carbon content (r=0.525), soil bulk density (r=0.268), soil urease (r=0.549) and soil dehydrogenase (r=0.492). Altitude (r=- 0.561) and soil moisture content (r=-0.051) showed negative correlation. Altitudinal gradient along with the vegetation and soil physico-chemical parameters were found to influence bacterial diversity and distribution. This study points out that this is a biome with a vast reservoir of bacteria which decrease with increasing altitudes, and highlights the microbiological importance of the poorly studied Eastern Himalayan range, justifying efforts to explore the prevalence of novel species in the biome.

Calculation of thermodynamic parameters of protein unfolding using far-ultraviolet circular dichroism

Abstract: Circular dichroism (CD) is an exceptional tool for rapid determination of thermodynamic parameters associated with the folding/unfolding of proteins. CD has the advantage that the measurements are quick, reliable and can be made under physiological conditions in a very short time. In this article, we summarize methods to obtain and analyze CD spectra to determine the conformational changes associated with the unfolding of proteins as a function of denaturants and temperature. Finally, recent developments with CD studies are discussed.

Cisplatin-induced genotoxic effects and endogenous glutathione levels in mice bearing ascites Dalton's lymphoma.

Abstract: cis-Diaminedichloroplatinum(II), commonly known as cisplatin, treatment of mice for 24-96, 30 h and 10 days caused the development of chromosomal aberrations in bone marrow cells as well as in Dalton's lymphoma (DL) cells, micronuclei (MN) in bone marrow cells and abnormalities in sperm heads, and it indicates the genotoxic potential of cisplatin in the host. Cisplatin exerts differential effects on the chromosomes of the bone marrow and tumor cells. Combination treatment of cisplatin with L-buthionine(S,R)-sulfoximine (BSO), an inhibitor of glutathione (GSH) synthesis, enhanced these cisplatin-induced genotoxic effects, but supplementing glutathione level with cysteine, its precursor, reduced the cisplatin-induced genotoxicity. The reduction in cellular glutathione level may facilitate increased intracellular accumulation and binding of drug to DNA to enhance the frequency of genotoxicity parameters. These findings support the possible involvement of glutathione as an important intracellular protective agent and suggest that differences in its levels may be one of the factors in the varying sensitivity of cells to cisplatin-induced genotoxic effects in the mice bearing ascites Dalton's lymphoma.

Lysozyme-luteolin binding: molecular insights into the complexation process and the inhibitory effects of luteolin towards protein modification.

Abstract: In the proposed work, the complexation of bioactive flavonoid luteolin with hen egg white lysozyme (HEWL) along with its inhibitory influence on HEWL modification has been explored with the help of multi-spectroscopic and computational methods. The binding affinity has been observed to be moderate in nature (in the order of 104 M−1) and the static quenching mechanism was found to be involved in the fluorescence quenching process. The binding constant (Kb) shows a progressive increase with the increase in temperature from (4.075 ± 0.046 × 104 M−1) at 293 K to (6.962 ± 0.024 × 104 M−1) at 313 K under experimental conditions. Spectroscopic measurements along with molecular docking calculations suggest that Trp62 is involved in the binding site of luteolin within the geometry of HEWL. The positive changes in enthalpy (ΔH = +19.99 ± 0.65 kJ mol−1) as well as entropy (ΔS = +156.28 ± 2.00 J K−1 mol−1) are indicative of the presence of hydrophobic forces that stabilize the HEWL–luteolin complex. The micro-environment around the Trp residues showed an increase in hydrophobicity as indicated by synchronous fluorescence (SFS), three dimensional fluorescence (3D) and red edge excitation (REES) studies. The % α-helix of HEWL showed a marked reduction upon binding with luteolin as indicated by circular dichroism (CD) and Fourier-transform infrared spectroscopy (FTIR) studies. Moreover, luteolin is situated at a distance of 4.275 ± 0.004 nm from the binding site as indicated by FRET theory, and the rate of energy transfer kET (0.063 ± 0.004 ns−1) has been observed to be faster than the donor decay rate (1/τD = 0.606 ns−1), which is indicative of the non-radiative energy transfer during complexation. Leaving aside the binding study, luteolin showed promising inhibitory effects towards the D-ribose mediated glycation of HEWL as well as towards HEWL fibrillation as studied by fluorescence emission and imaging studies. Excellent correlation with the experimental observations as well as precise location and dynamics of luteolin within the binding site has been obtained from molecular docking and molecular dynamics simulation studies.