Showing papers by "North Eastern Hill University published in 2019"

Blockchain‐based security aspects in heterogeneous Internet‐of‐Things networks: A survey

Abstract: Blockchain is a key technology that enables cryptocurrencies such as Bitcoin, Litecoin, etc. In recent years, researchers have ventured into tapping the potential of blockchain‐based ecosy...

Autophagy Modulation as a Treatment of Amyloid Diseases

Abstract: Amyloids are fibrous proteins aggregated into toxic forms that are implicated in several chronic disorders. More than 30 diseases show deposition of fibrous amyloid proteins associated with cell loss and degeneration in the affected tissues. Evidence demonstrates that amyloid diseases result from protein aggregation or impaired amyloid clearance, but the connection between amyloid accumulation and tissue degeneration is not clear. Common examples of amyloid diseases are Alzheimer’s disease (AD), Parkinson’s disease (PD) and tauopathies, which are the most common forms of neurodegenerative diseases, as well as polyglutamine disorders and certain peripheral metabolic diseases. In these diseases, increased accumulation of toxic amyloid proteins is suspected to be one of the main causative factors in the disease pathogenesis. It is therefore important to more clearly understand how these toxic amyloid proteins accumulate as this will aide in the development of more effective preventive and therapeutic strategies. Protein homeostasis, or proteostasis, is maintained by multiple cellular pathways—including protein synthesis, quality control, and clearance—which are collectively responsible for preventing protein misfolding or aggregation. Modulating protein degradation is a very complex but attractive treatment strategy used to remove amyloid and improve cell survival. This review will focus on autophagy, an important clearance pathway of amyloid proteins, and strategies for using it as a potential therapeutic target for amyloid diseases. The physiological role of autophagy in cells, pathways for its modulation, its connection with apoptosis, cell models and caveats in developing autophagy as a treatment and as a biomarker is discussed.

Green chemistry synthesis of biocompatible ZnS quantum dots (QDs): their application as potential thin films and antibacterial agent

Abstract: We are presenting here the synthesis of quantum dots (QDs) of direct band gap semiconductor, cubic ZnS through modified green chemistry-mediated chemical precipitation reaction. Green chemistry-synthesized (GCS) ZnS QDs were characterized using powder X-ray diffraction and high-resolution transmission electron microscope techniques. Analysis of results, revealed by both the techniques for the synthesized QDs, is complementary as far as the size range (2–6 nm) of ZnS QDs is concerned. UV–Vis spectrophotometric spectrum (λmax = 314 nm) showed a conspicuous blue shift than the bulk. The Fourier-transformed infrared spectra convincingly reported a Zn–S bond stretching frequency at 649 cm−1. The characterized QDs were subjected to the preparation of thin films over SiO2 template (57 nm thickness) using photoresist spin coating technique at the ambient condition. The surface topology of nanoscale-thick films was studied by atomic force microscope (roughness parameter—33.28 nm, rms; for a scan area of 3.48 × 3.48 μm2). The symmetrical (skewness = 1.68) and random distribution (kurtosis = 2.93) of the peaks and valleys revealed the nanoscale-thick films of ZnS QDs. Zeta potential (− 9.2 mV) fairly proved stable existence of ZnS QDs. The GCS QDs were found to be non-toxic toward L929 mouse fibroblastic cells and human erythrocytes. However, they demonstrated significant inhibitory effects against seven bacterial pathogens with an average zone of inhibition of 1.5 cm at 100 μg/ml concentration. The minimum inhibitory concentrations determined were in the range of 75 to 125 μg/ml for gram-positive and 100 to 150 μg/ml for gram-negative bacterial pathogens.

Pyrene-Based Chemosensor for Picric Acid-Fundamentals to Smartphone Device Design.

Abstract: Developing a fluorescent probe for the selective and sensitive detection of explosives is a topic of continuous research interest. Additionally, underlying the principles behind the detection mechanism is indeed providing substantial information about the design of an efficient fluorescence probe. In this context, a pyrene-tethered 1-(pyridin-2-yl)imidazo[1,5-a]pyridine-based fluorescent probe (TL18) was developed and employed as a fluorescent chemosensor for nitro explosives. The molecular structure of TL18 was well-characterized by NMR and EI-MS spectrometric techniques. UV-visible absorption, steady-state, and time-resolved fluorescence spectroscopic techniques have been employed to explicate the photophysical properties of TL18. The fluorescent nature of the TL18 probe was explored for detection of nitro explosives. Intriguingly, the TL18 probe was selectively responsive to picric acid over other explosives. The quantitative analysis of the fluorescence titration studies of TL18 with picric acid proved that the probe achieved a detection limit of 63 nM. Further, DFT and QTAIM studies were used to establish the nature of the sensing mechanism of TL18. The hydrogen-bonding interactions are the reason for the imperative sensing property of TL18 for picric acid. Thus, our experimental and theoretical studies provide an adequate and appropriate prerequisite for an efficient fluorescent probe. Furthermore, a smartphone-interfaced portable fluorimeter module is developed to facilitate sensitive and real-time sensing of picric acid. This portable module was capable of detecting picric acid down to 99 nM. Eventually, these studies will have a significant impact on development and application of a new class of chemosensors for detection of explosives.

Organoiridium(III) Complexes as Luminescence Color Switching Probes for Selective Detection of Nerve Agent Simulant in Solution and Vapor Phase.

Abstract: In this work, cationic organoiridium(III) complex based photoluminescent (PL) probes have been developed to selectively detect the chemical warfare nerve agent mimic, diethyl chlorophosphate(DCP) at nanomolar range by distinct bright green to orange-red luminescence color switching (on-off-on) in solution as well as in the vapor phase. Interference of other chemical warfare agents (CWAs) and their mimics was not observed either by PL spectroscopy or with the naked-eye in solution and gas phase. The detection was attained via a simultaneous nucleophilic attack of two -OH groups of the 4,7-dihydroxy-1,10-phenanthroline ligand with DCP by forming bulkier phosphotriester. The detailed reaction mechanism was established through extensive 1H NMR titration, 31P NMR, and ESI-MS analysis. Finally, a test paper strip and solid poly(ethylene oxide) (PEO) film with iridium(III) complex 1[PF6] were fabricated for the vapor-phase detection of DCP. The solution and vapor-phase detection properties of these luminescent Ir(III) complexes can offer a worthy approach into the design of new metal complex based PL switching probes for chemical warfare agents.

Redox-Mediated Shape Transformation of Fe3O4 Nanoflakes to Chemically Stable Au−Fe2O3 Composite Nanorods for a High-Performance Asymmetric Solid-State Supercapacitor Device

Abstract: Development of a stable and highly active metal oxide based electrochemical supercapacitor is a major challenge. Herein, we report a Au–Fe2O3 nanocomposite having tiny amount of gold (3 atomic % Au...

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.

Structural and energetic understanding of novel natural inhibitors of Mycobacterium tuberculosis malate synthase

Abstract: Persistent infection by Mycobacterium tuberculosis requires the glyoxylate shunt This is a bypass to the tricarboxylic acid cycle in which isocitrate lyase (ICL) and malate synthase (MS) catalyze the net incorporation of carbon during mycobacterial growth on acetate or fatty acids as the primary carbon source To identify a potential antitubercular compound, we performed a structure-based screening of natural compounds from the ZINC database (n = 1 67 740) against the M tuberculosis MS (MtbMS) structure The ligands were screened against MtbMS, and 354 ligands were found to have better docking score These compounds were assessed for Lipinski and absorption, distribution, metabolism, excretion, and toxicity prediction where 15 compounds were found to fit well for redocking studies After refinement by molecular docking and drug-likeness analysis, four potential inhibitors (ZINC1483899, ZINC1754310, ZINC2269664, and ZINC15729522) were identified These four ligands with phenyl-diketo acid were further subjected to molecular dynamics simulation to compare the dynamics and stability of the protein structure after ligand binding The binding energy analysis was calculated to determine the intermolecular interactions Our results suggested that the four compounds had a binding free energy of -20196, -24202, -18703, and -16902 kJ·mol-1 , for compounds with IDs ZINC1483899, ZINC1754310, ZINC2269664, and ZINC15729522, respectively We concluded that two compounds (ZINC1483899 and ZINC1754310) displayed considerable structural and pharmacological properties and could be probable drug candidates to fight against M tuberculosis parasites

Association of EGLN1 gene with high aerobic capacity of Peruvian Quechua at high altitude.

Abstract: Highland native Andeans have resided at altitude for millennia. They display high aerobic capacity (VO2max) at altitude, which may be a reflection of genetic adaptation to hypoxia. Previous genomewide (GW) scans for natural selection have nominated Egl-9 homolog 1 gene (EGLN1) as a candidate gene. The encoded protein, EGLN1/PHD2, is an O2 sensor that controls levels of the Hypoxia Inducible Factor-α (HIF-α), which regulates the cellular response to hypoxia. From GW association and analysis of covariance performed on a total sample of 429 Peruvian Quechua and 94 US lowland referents, we identified 5 EGLN1 SNPs associated with higher VO2max (L⋅min-1 and mL⋅min-1⋅kg-1) in hypoxia (rs1769793, rs2064766, rs2437150, rs2491403, rs479200). For 4 of these SNPs, Quechua had the highest frequency of the advantageous (high VO2max) allele compared with 25 diverse lowland comparison populations from the 1000 Genomes Project. Genotype effects were substantial, with high versus low VO2max genotype categories differing by ∼11% (e.g., for rs1769793 SNP genotype TT = 34.2 mL⋅min-1⋅kg-1 vs. CC = 30.5 mL⋅min-1⋅kg-1). To guard against spurious association, we controlled for population stratification. Findings were replicated for EGLN1 SNP rs1769793 in an independent Andean sample collected in 2002. These findings contextualize previous reports of natural selection at EGLN1 in Andeans, and support the hypothesis that natural selection has increased the frequency of an EGLN1 causal variant that enhances O2 delivery or use during exercise at altitude in Peruvian Quechua.

Short-chain fatty acid and vitamin production potentials of Lactobacillus isolated from fermented foods of Khasi Tribes, Meghalaya, India

Abstract: Vitamins and SCFA (short-chain fatty acids) production from Lactobacillus isolates are studied due to its health benefits to the human hosts. Lactobacillus strains are widely used in fermented foods, and few of them are reported with vitamin and SCFA production potential. Therefore, in the present study, vitamins and SCFA production capability of isolates were studied to find the potent Lactobacillus cultures for value-added functional food product development. Five Lactobacillus strains, i.e., KGL2, KGL3A, KGL4, RNS4, and WTS4, were isolated from rice-based traditional fermented foods of Garo Hills, Meghalaya, India. All the well grown isolates were morphologically, physiologically, and genetically characterized. Then, vitamins and SCFA were estimated using HPLC based methods. Vitamins produced in vitamins free assay medium and SCFA in milk medium are produced by Lactobacillus. Lactic acid bacteria produce essential vitamins like riboflavin, folate, cobalamin, and SCFA which have health impacts (anti-obesity, anti-diabetics, anti-microbial, and other chronic diseases prevention) to the host. These vitamins are essential for cellular and metabolic growth of living system. In the study, five potent Lactobacillus isolates viz., KGL2 (Lactobacillus fermentum), KGL3A (Lactobacillus plantarum), KGL4 (Lactobacillus fermentum), RNS4 (Lactobacillus rhamnosus), and WTS4 (Lactobacillus fermentum) were considered for vitamins (B2, B12, and B9) and SCFA productions (lactate, butyrate, and acetate). However, KGL3A had shown highest B2 production (0.7 μg/ml) while KGL2 exhibited maximum B12 production (0.05 μg/ml) after 36 h. Moreover, WTS4 attributed highest folate production (0.09 μg/ml) after 24 h. In addition, RNS4 reported the maximum short-chain fatty acid production (0.77 g/l acetic acid, 0.26 g/l lactic acid, and 0.008 g/l butyric acid respectively). Potent Lactobacillus isolates from traditional fermented foods of Garo Hills, Meghalaya, India (North East Part of India) showed maximum production of B2, B9, and B12 as well as short-chain fatty acids and could be used for their application as health beneficial functional fermented dairy products.

Coordination geometry-induced optical imaging of l-cysteine in cancer cells using imidazopyridine-based copper(ii) complexes.

Abstract: Overexpression of cysteine cathepsins proteases has been documented in a wide variety of cancers, and enhances the l-cysteine concentration in tumor cells. We report the synthesis and characterization of copper(ii) complexes [Cu(L1)2(H2O)](SO3CF3)2, 1, L1 = 3-phenyl-1-(pyridin-2-yl)imidazo[1,5-a]pyridine, [Cu(L2)2(SO3CF3)]SO3CF3, 2, L2 = 3-(4-methoxyphenyl)-1-pyridin-2-yl-imidazo[1,5-a]pyridine, [Cu(L3)2(H2O)](SO3CF3)2, 3, L3 = 3-(3,4-dimethoxy-phenyl)-1-pyridin-2-yl-imidazo[1,5-a]pyridine and [Cu(L4)2(H2O)](SO3CF3)2, 4, L4 = dimethyl-[4-(1-pyridin-2-yl-imidazo[1,5-a]pyridin-3-yl)phenyl]amine as 'turn-on' optical imaging probes for l-cysteine in cancer cells. The molecular structure of complexes adopted distorted trigonal pyramidal geometry (τ, 0.68-0.87). Cu-Npy bonds (1.964-1.989 A) were shorter than Cu-Nimi bonds (2.024-2.074 A) for all complexes. Geometrical distortion was strongly revealed in EPR spectra, showing g‖ (2.26-2.28) and A‖ values (139-163 × 10-4 cm-1) at 70 K. The d-d transitions appeared around 680-741 and 882-932 nm in HEPES, which supported the existence of five-coordinate geometry in solution. The Cu(ii)/Cu(i) redox potential of 1 (0.221 V vs. NHE) was almost identical to that of 2 and 3 but lower than that of 4 (0.525 V vs. NHE) in HEPES buffer. The complexes were almost non-emissive in nature, but became emissive by the interaction of l-cysteine in 100% HEPES at pH 7.34 via reduction of Cu(ii) to Cu(i). Among the probes, probe 2 showed selective and efficient turn-on fluorescence behavior towards l-cysteine over natural amino acids with a limit of detection of 9.9 × 10-8 M and binding constant of 2.3 × 105 M-1. The selectivity of 2 may have originated from a nearly perfect trigonal plane adopted around a copper(ii) center (∼120.70°), which required minimum structural change during the reduction of Cu(ii) to Cu(i) while imaging Cys. The other complexes, with their distorted trigonal planes, required more reorganizational energy, which resulted in poor selectivity. Probe 2 was employed for optical imaging of l-cysteine in HeLa cells and macrophages. It exhibited brighter fluorescent images by visualizing Cys at pH 7.34 and 37 °C. It showed relatively less toxicity for these cell lines as ascertained by the MTT assay.

Novel coumarin derivatives as potent acetylcholinesterase inhibitors: insight into efficacy, mode and site of inhibition

Abstract: The inhibitory efficacy of two substituted coumarin derivatives on the activity of neurodegenerative enzyme acetylcholinesterase (AChE) was assessed in aqueous buffer as well as in the presence of ...

Plant Growth-Promoting Abilities in Cyanobacteria

Abstract: Cyanobacteria (blue-green algae) are photosynthetic prokaryotes having oxygenic photosynthesis. Several species of cyanobacteria also carry out N2 fixation. They produce a variety of compounds/products useful to mankind. The association of these microorganisms influences plant growth, development, and susceptibility to pathogens. This chapter focuses on their plant growth-promoting abilities. Cyanobacteria are of great use as biofertilizer particularly for the rice crop. Free-living N2-fixing cyanobacteria as well as Azolla (a symbiotic association of water fern Azolla and Nostoc/Anabaena) are commonly used as biofertilizer for the rice as well as several other crops. In addition, these organisms are also used to improve soil quality, particularly for the reclamation of Usar (alkaline) soils making them suitable for plant growth. Some N2-fixing cyanobacteria occur in symbiosis and in associations with a wide spectrum of plants wherein they provide fixed nitrogen directly to the plant partner enabling them to grow in nitrogen-poor soils. In some symbioses, for example in bipartite lichens, cyanobacterial partner provides both fixed-N as well as fixed-C to the plant partner. Cyanobacteria are also known to excrete a number of other substances that influence plant growth and development. They have been reported to produce growth-promoting regulators (resembling gibberellin, cytokinin, abscisic acid, and auxin), vitamins (particularly vitamin B), amino acids, polypeptides, and exopolysaccharides that act as antibacterial, antifungal, and toxin-like substances. Cyanobacteria also have the ability to mobilize insoluble organic phosphates for the benefit of the crop plants.

Functional interplay between YY1 and CARM1 promotes oral carcinogenesis.

Abstract: Coactivator associated arginine methyltransferase 1 (CARM1) has been functionally implicated in maintenance of pluripotency, cellular differentiation and tumorigenesis; where it plays regulatory roles by virtue of its ability to coactivate transcription as well as to modulate protein function as an arginine methyltransferase. Previous studies establish an oncogenic function of CARM1 in the context of colorectal and breast cancer, which correlate to its overexpressed condition. However, the mechanism behind its deregulated expression in the context of cancer has not been addressed before. In the present study we uncover an oncogenic function of CARM1 in the context of oral cancer, where it was found to be overexpressed. We also identify YY1 to be a positive regulator of CARM1 gene promoter, where silencing of YY1 in oral cancer cell line could lead to reduction in expression of CARM1. In this context, YY1 showed concomitant overexpression in oral cancer patient samples compared to adjacent normal tissue. Cell line based experiments as well as xenograft study revealed pro-neoplastic functions of YY1 in oral cancer. Transcriptomics analysis as well as qRT-PCR validation clearly indicated pro-proliferative, pro-angiogenic and pro-metastatic role of YY1 in oral cancer. We also show that YY1 is a substrate of CARM1 mediated arginine methylation, where the latter could coactivate YY1 mediated reporter gene activation in vivo. Taken together, CARM1 and YY1 were found to regulate each other in a positive feedback loop to facilitate oral cancer progression.

Exploring Medicinal Plant Legacy for Drug Discovery in Post-genomic Era

Abstract: Plants are a valuable source of pharmacologically important compounds since these are traditionally important in medicinal systems. Medicinal plant-based ancient wisdom could serve as a powerful tool to facilitate focused research on natural compounds for the drug discovery process. Medicinal plants are more important sources for drug discovery, specifically lead molecules as these offer several advantages over the synthetic molecules. Since in post genomic era, molecular targets for most diseases are known, conventional bioscreening strategies for medicinal plants are not sufficient to fulfill the present demand. It makes the role of medicinal plants more significant than ever before. The rich heritage of Indian medicinal plants can be explored utilizing various computational approaches for bioprospecting in the post-genomic era. In this review, the authors explore how Indian medicinal plant legacy can be utilized in post-genomic era utilizing the computational, bioinformatics, chemo-informatics, genomics and systems biology approaches. This approach shall make possible the systematic analysis integrating traditional and modern data in order to validate medicinal plant based knowledge.

An insight into the binding of 6-hydroxyflavone with hen egg white lysozyme: a combined approach of multi-spectroscopic and computational studies.

Abstract: The interaction of 6-hydroxyflavone (6HF) with hen egg white lysozyme (HEWL) has been executed using multi-spectroscopic and computational methods. Steady state fluorescence studies indicat...

Water-Mediated Selenium Hydrogen-Bonding in Proteins: PDB Analysis and Gas-Phase Spectroscopy of Model Complexes

Abstract: High-resolution X-ray crystallography and two-dimensional NMR studies demonstrate that water-mediated conventional hydrogen-bonding interactions (N-H···N, O-H···N, etc.) bridging two or more amino acid residues contribute to the stability of proteins and protein-ligand complexes. In this work, we have investigated single water-mediated selenium hydrogen-bonding interactions (unconventional hydrogen-bonding) between amino acid residues in proteins through extensive protein data bank (PDB) analysis coupled with gas-phase spectroscopy and quantum chemical calculation of a model complex consisting of indole, dimethyl selenide, and water. Here, indole and dimethyl selenide represent the amino acid residues tryptophan and selenomethionine, respectively. The current investigation demonstrates that the most stable structure of the model complex observed in the IR spectroscopy mimics single water-mediated selenium hydrogen-bonded structural motifs present in the crystal structures of proteins. The present work establishes that water-mediated Se hydrogen-bonding interactions are ubiquitous in proteins and the number of these interactions observed in the PDB is more than that of direct Se hydrogen-bonds present there.

Entrepreneurial intention, job satisfaction and organisation commitment - construct of a research model through literature review

Abstract: Intention is a human behavior. Measurement of intention in terms of entrepreneurial mindset is becoming a researchable topic. During the past years, the factors namely lack of fund, lack of raw materials, unskilled employees etc. were mostly considered to be the deterrents of initiation and development of entrepreneurial activities. But, with the various development provisions are made by the concern authorities, it leads to the emergence of entrepreneurial intention as an important factor. The present paper is a humble effort to develop a research model of the relationship between entrepreneurial intention, job satisfaction and organisation commitment.