Browsing by Author "Singh, A."

Now showing 1 - 6 of 6
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    Carrageenan based hydrogels and composites: A systematic investigation reporting their multidimentional essence
    (Nova Science Publishers, Inc., 2016) Ul Rehman, W.; Majeed, A.; Rani, P.; Saini, K.C.; Najar, R.A.; Mehra, R.; Singh, A.; Bast, Felix
    Carrageenans are red seaweed extracted sulfated linear polysaccharides which possess excellent gel forming properties. They are extensively used for their thickening, gel forming as well as stabilizing properties in food industries. Due to their good protein binding abilities, they are preferred in meat and dairy preservation. Structurally, they are polymers of alternately repeating disaccharide unit, ?-(133)-D-galactose and ?-(134)-3,6- anhydro-D- or L-galactose. Sulphation of the galactose gives them the distinguishing properties. Three isomeric forms of carrageenan with slightly different properties exist in nature. Their hydrogels are used in tissue engineering and controlled drug delivery while their composites find applications in wound dressings, protection of fish and meat from dehydration. In the field of medicine, carrageenans possess anticoagulant, antithrombotic, antiviral, and antitumor activities. Besides they also possess many industrial applications. ? 2016 Nova Science Publishers, Inc.
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    Cellulose: A multifaceted biopolymer
    (Nova Science Publishers, Inc., 2016) Majeed, A.; Najar, R.A.; Ul Rehman, W.; Choudhary, S.; Thakur, S.; Singh, A.; Sharma, G.; Bhardwaj, P.
    Cellulose is a common natural polymer with a wide range of industrial, medical, bio fuel, agricultural, textile and paper applications. It exhibits various levels of structural organizations, from individual glucose chains through microfibrils, macrofibrils to cellulose fibers. The synthesizing machinery of cellulose consists of a six subunit plasmamembrane protein complex, cellulose synthase, organized into a rosette structure. Plant cellulose synthases possess additional plant specific motifs that are absent in bacteria. Among the different solvent systems developed for cellulose dissolution, ionic liquids stand at the forefront. Microorganism mediated energy release from cellulose facilitates its use in fuel cells as a source of energy. The nanocomposites of cellulose have revolutionized the medical field and are being chiefly used in tissue engineering, ligament engineering and wound healing. The chemical structure of cellulose make it suitable to form hydrogels which are used in tissue engineering, cartilage modelling, bone implantation, cell culture scaffolds, enhanced drug delivery, heavy metal absorbance, and in retaining soil water and efficient fertilizer release for agricultural efficiency. Besides, cellulose based ethanol production help to reduce the pressure on conventional sources of energy. This chapter focuses on cellulose structure, its synthesizing machinery, trafficking, genes and proteins involved, solubility and solvent systems, its derivatives, composites, hydrogels, fuel cells, ethanol production and degradation. ? 2016 Nova Science Publishers, Inc.
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    A chromatin modifier integrates insulin/IGF-1 signalling and dietary restriction to regulate longevity
    (Blackwell Publishing Ltd, 2016) Singh, A.; Kumar, N.; Matai, L.; Jain, V.; Garg, A.; Mukhopadhyay, A.
    Insulin/IGF-1-like signalling (IIS) and dietary restriction (DR) are the two major modulatory pathways controlling longevity across species. Here, we show that both pathways license a common chromatin modifier, ZFP-1/AF10. The downstream transcription factors of the IIS and select DR pathways, DAF-16/FOXO or PHA-4/FOXA, respectively, both transcriptionally regulate the expression of zfp-1. ZFP-1, in turn, negatively regulates the expression of DAF-16/FOXO and PHA-4/FOXA target genes, apparently forming feed-forward loops that control the amplitude as well as the duration of gene expression. We show that ZFP-1 mediates this regulation by negatively influencing the recruitment of DAF-16/FOXO and PHA-4/FOXA to their target promoters. Consequently, zfp-1 is required for the enhanced longevity observed during DR and on knockdown of IIS. Our data reveal how two distinct sensor pathways control an overlapping set of genes, using different downstream transcription factors, integrating potentially diverse and temporally distinct nutritional situations. ? 2016 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.
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    Genome-wide endogenous DAF-16/FOXO recruitment dynamics during lowered insulin signalling in C. elegans
    (Impact Journals LLC, 2015) Kumar, N.; Jain, V.; Singh, A.; Jagtap, U.; Verma, S.; Mukhopadhyay, A.
    Lowering insulin-IGF-1-like signalling (IIS) activates FOXO transcription factors (TF) to extend life span across species. To study the dynamics of FOXO chromatin occupancy under this condition in C. elegans, we report the first recruitment profile of endogenous DAF-16 and show that the response is conserved. DAF-16 predominantly acts as a transcriptional activator and binding within the 0.5 kb promoter-proximal region results in maximum induction of downstream targets that code for proteins involved in detoxification and longevity. Interestingly, genes that are activated under low IIS already have higher DAF-16 recruited to their promoters in WT. DAF- 16 binds to variants of the FOXO consensus sequence in the promoter proximal regions of genes that are exclusively targeted during low IIS. We also define a set of 'core' direct targets, after comparing multiple studies, which tend to co-express and contribute robustly towards IIS-associated phenotypes. Additionally, we show that nuclear hormone receptor DAF-12 as well as zinc-finger TF EOR-1 may bind DNA in close proximity to DAF-16 and distinct TF classes that are direct targets of DAF-16 may be instrumental in regulating its indirect targets. Together, our study provides fundamental insights into the transcriptional biology of FOXO/DAF-16 and gene regulation downstream of the IIS pathway.
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    Starch: A precise account covering its multidimensional aspects
    (Nova Science Publishers, Inc., 2017) Majeed, A.; Ul Rehman, W.; Najar, R.A.; Choudhary, S.; Thakur, S.; Singh, A.; Sharma, G.; Bhardwaj, P.
    Starch is the main storage carbohydrate of plants and is composed of glucose residues linked together by ? 1-4 glycosidic bonds. The starch molecule consists of a linear amylose and highly branched amylopectin. Starch forms the main energy source in human diets and is present in large quantities in our common foods like rice, wheat, maize, etc. Granule-bound starch synthase is responsible for amylose synthesis while amylopectin requires the action of starch synthases plus branching enzymes. The degradation of starch requires another set of enzymes including ?-amylase and debranching enzyme. Microorganisms can be employed to produce the starch degrading enzymes thereby yielding the high glucose and fructose syrups. Starch is a good candidate for generating electricity in microbial fuel cells. Besides, ethanol production is yet another application for energy production that can lessen the pressure on conventional petroleum-based fuels. The hydrogels and composites of starch are widely used in pharmaceutical and cosmetic industries, agriculture and medicine especially tissue engineering. Besides the starch itself, its derivatives have a wide range of industrial applications. This chapter focuses on starch structure, synthesis, derivatives, composites, hydrogels, energy production, cosmetic and other industrial applications. ? 2017 Nova Science Publishers, Inc.
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    Transcriptome characterization and screening of molecular markers in ecologically important Himalayan species (Rhododendron arboreum)
    (Canadian Science Publishing, 2018) Choudhary, S.; Thakur, S.; Najar, R.A.; Majeed, A.; Singh, A.; Bhardwaj, P.; Crease, T.
    Rhododendron arboreum is an ecologically prominent species, which also lends commercial and medicinal benefits in the form of palatable juices and useful herbal drugs. Local abundance and survival of the species under a highly fluctuating climate make it an ideal model for genetic structure and functional analysis. However, a lack of genomic data has hampered additional research. In the present study, cDNA libraries from floral and foliar tissues of the species were sequenced to provide a foundation for understanding the functional aspects of the genome and to construct an enriched repository that will promote genomics studies in the genera. Illumina's platform facilitated the generation of ?100 million high-quality paired-end reads. De novo assembly, clustering, and filtering out of shorter transcripts predicted 113 167 non-redundant transcripts with an average length of 1164.6 bases. Of these, 71 961 transcripts were categorized based on functional annotations in the Gene Ontology database, whereby 5710 were grouped into 141 pathways and 23 746 encoded for different transcription factors. Transcriptome screening further identified 35 419 microsatellite regions, of which, 43 polymorphic loci were characterized on 30 genotypes. Seven hundred and nineteen transcripts had 811 high-quality single-nucleotide polymorphic variants with a minimum coverage of 10, a total score of 20, and SNP% of 50. ? 2018 Published by NRC Research Press.