Ashutosh Pandey - Academia.edu (original) (raw)

Papers by Ashutosh Pandey

Plant cell reports, 2012

Scientific reports, 2014

Flavonoids, due to their pharmacological attributes, have recently become target molecules for me... more Flavonoids, due to their pharmacological attributes, have recently become target molecules for metabolic engineering in commonly consumed food crops. Strategies including expression of single genes and gene pyramiding have provided only limited success, due principally to the highly branched and complex biosynthetic pathway of the flavonoids. Transcription factors have been demonstrated as an efficient tool for metabolic engineering of this pathway, but often exhibit variation in heterologous systems relative to that in the homologous system. In the present work, Arabidopsis MYB transcription factor, AtMYB111, has been expressed in tobacco to study whether this can enhance flavonoid biosynthesis in heterologous system. The results suggest that AtMYB111 expression in transgenic tobacco enhances expression of genes of the phenylpropanoid pathway leading to an elevated content of flavonols. However, dark incubation of transgenic and wild type (WT) plants down-regulated both the express...

BioResearch open access, 2014

Hydrogen peroxide (H2O2) acts as a signaling molecule and modulates various aspects of cell funct... more Hydrogen peroxide (H2O2) acts as a signaling molecule and modulates various aspects of cell functions in a wide variety of cells including mammalian germ cells. We examined whether a decreased level of intra-oocyte cyclic 3',5'-adenosine monophosphate (cAMP) leads to accumulation of H2O2, and if so, whether a moderate increase of H2O2 inactivates maturation promoting factor (MPF) during spontaneous resumption of meiosis in rat oocytes cultured in vitro. Removal of cumulus cells and culture of denuded oocytes in vitro significantly decreased oocyte cAMP level and led to spontaneous meiotic resumption from diplotene arrest. The reduced oocyte cAMP level was associated with an increased oocyte H2O2 level and reduced catalase activity. Exogenous supplementation of H2O2 induced meiotic resumption from diplotene arrest in a concentration- and time-dependent manner in oocytes treated with 0.1 mM of 3-isobutyl-1-methylxanthine, while dibutyryl-cAMP and 3-t-butyl-4-hydroxyanisole inh...

PLoS ONE, 2014

What proportion of genes with intense and selective expression in specific tissues, cells, or sys... more What proportion of genes with intense and selective expression in specific tissues, cells, or systems are still almost completely uncharacterized with respect to biological function? In what ways do these functionally enigmatic genes differ from well-studied genes? To address these two questions, we devised a computational approach that defines so-called ignoromes. As proof of principle, we extracted and analyzed a large subset of genes with intense and selective expression in brain. We find that publications associated with this set are highly skewed-the top 5% of genes absorb 70% of the relevant literature. In contrast, approximately 20% of genes have essentially no neuroscience literature. Analysis of the ignorome over the past decade demonstrates that it is stubbornly persistent, and the rapid expansion of the neuroscience literature has not had the expected effect on numbers of these genes. Surprisingly, ignorome genes do not differ from well-studied genes in terms of connectivity in coexpression networks. Nor do they differ with respect to numbers of orthologs, paralogs, or protein domains. The major distinguishing characteristic between these sets of genes is date of discovery, early discovery being associated with greater research momentum-a genomic bandwagon effect. Finally we ask to what extent massive genomic, imaging, and phenotype data sets can be used to provide high-throughput functional annotation for an entire ignorome. In a majority of cases we have been able to extract and add significant information for these neglected genes. In several cases-ELMOD1, TMEM88B, and DZANK1-we have exploited sequence polymorphisms, large phenome data sets, and reverse genetic methods to evaluate the function of ignorome genes.

Plant Biotechnology Journal, 2014

Environmental Pollution, 2013

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Bioresource Technology, 2011

The sporophyte and gametophyte of Pteris vittata are arsenic hyperaccumulators, however, little i... more The sporophyte and gametophyte of Pteris vittata are arsenic hyperaccumulators, however, little is known about the mechanism by which the gametophyte deals with this toxic element. An in vitro system (spores grown in arsenic amended nutrient media) was used to investigate the impact of arsenic on growth of the gametophyte and the role of antioxidative systems in combating As-stress. When mature spores of P. vittata were grown in medium amended with 0-50 mg kg À1 of arsenic (as arsenate), the arsenic concentration in the gametophyte increased, with increasing arsenate in the media, but did not inhibit the spore germination and biomass development. Increases in the level of antioxidant enzymes, superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, and glutathione-Stransferase) and of ascorbic acid and glutathione probably enabled the gametophyte to withstand the oxidative stress caused by arsenate.

Biochimica et Biophysica Acta (BBA) - General Subjects, 2013

Amorphous silica nanoparticles (aSNPs) are used for various applications including food industry.... more Amorphous silica nanoparticles (aSNPs) are used for various applications including food industry. However, limited in vivo studies are available on absorption/internalization of ingested aSNPs in the midgut cells of an organism. The study aims to examine cellular uptake of aSNPs (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;30nm) in the midgut of Drosophila melanogaster (Oregon R(+)) owing to similarities between the midgut tissue of this organism and human and subsequently cellular stress response generated by these nanoparticles. Third instar larvae of D. melanogaster were exposed orally to 1-100μg/mL of aSNPs for 12-36h and oxidative stress (OS), heat shock genes (hsgs), membrane destabilization (Acridine orange/Ethidium Bromide staining), cellular internalization (TEM) and apoptosis endpoints. A significant increase was observed in OS endpoints in the midgut cells of exposed Drosophila in a concentration- and time-dependent manner. Significantly increased expression of hsp70 and hsp22 along with caspases activation, membrane destabilization and mitochondrial membrane potential loss was also observed. TEM analysis showed aSNPs-uptake in the midgut cells of exposed Drosophila via endocytic vesicles and by direct membrane penetration. aSNPs after their internalization in the midgut cells of exposed Drosophila larvae show membrane destabilization along with increased cellular stress and cell death. Ingested aSNPs show adverse effects on the cells of GI tract of the exposed organism thus their industrial use as a food-additive may raise concern to human health.

A rapid, sensitive and simple high performance liquid chromatography photo diode array mass spect... more A rapid, sensitive and simple high performance liquid chromatography photo diode array mass spectrometry (HPLC-PDA-MS-MS) method was developed for the simultaneous determination of nine compounds viz. psoralen (furocoumarin), daidzein, genistein (isoflavonoids), daidzin and genestin (isoflavone glycosides), biochanin A (methoxylated isoflavone) and quercetin, kaempferol and rutin (flavonols). Chromatographic separation of these nine molecules was performed on RP C18 column within 20

... Niranjan , A. ; Barthwal , J. ; Govindrajan , R. ; Singh , DP ; Lehri , A. ; Rawat , AKS ; Am... more ... Niranjan , A. ; Barthwal , J. ; Govindrajan , R. ; Singh , DP ; Lehri , A. ; Rawat , AKS ; Amla , DV Development and Validation of HPLC-UV-MS-MS Method for Identification and Quantification of Polyphenols ... Abhishek Niranjan and Ashutosh Pandey contributed equally to this work. ...

Journal of cellular …, 2010

Mammalian ovary is metabolically active organ and generates by-products such as reactive oxygen s... more Mammalian ovary is metabolically active organ and generates by-products such as reactive oxygen species (ROS) and reactive nitrogen species (RNS) on an extraordinary scale. Both follicular somatic cells as well as oocyte generate ROS and RNS synchronously and their effects are neutralized by intricate array of antioxidants. ROS such as hydrogen peroxide (H 2 O 2 ) and RNS such as nitric oxide (NO) act as signaling molecules and modulate various aspects of oocyte physiology including meiotic cell cycle arrest and resumption. Generation of intraoocyte H 2 O 2 can induce meiotic resumption from diplotene arrest probably by the activation of adenosine monophosphate (AMP)activated protein kinase A (PRKA)-or Ca 2þ -mediated pathway. However, reduced intraoocyte NO level may inactivate guanylyl cyclasemediated pathway that results in the reduced production of cyclic 3 0 ,5 0 -guanosine monophosphate (cGMP). The reduced level of cGMP results in the activation of cyclic 3 0 ,5 0 -adenosine monophosphate (cAMP)-phosphodiesterase 3A (PDE3A), which hydrolyses cAMP. The reduced intraoocyte cAMP results in the activation of maturation promoting factor (MPF) that finally induces meiotic resumption. Thus, a transient increase of intraoocyte H 2 O 2 level and decrease of NO level may signal meiotic resumption from diplotene arrest in mammalian oocytes.

Plant cell reports, 2010

Isoflavones are known to possess medicinal properties and implicated in plant-pathogen interactio... more Isoflavones are known to possess medicinal properties and implicated in plant-pathogen interaction. We have for the first time isolated and functionally characterized an isoflavones synthase (IFS) gene from a traditionally acclaimed medicinal plant Psoralea corylifolia abundantly growing in tropical and subtropical regions. The IFS catalyzes the exclusive reaction of phenylpropanoid pathway in leguminous plants to produce isoflavones. The full-length cDNA (PcIFS) of the gene comprised 1,563 bp and putatively encodes a polypeptide of 520 amino acid residues. The gene is expressed ubiquitously although at varying levels in different parts of the plant. The expression analysis suggests that the gene is responsive to methyl jasmonate, salicylic acid and wounding. Overexpression of PcIFS in non-leguminous tobacco plant led to the accumulation of isoflavones in petal tissue, suggesting it a functional gene from P. corylifolia involved in isoflavones biosynthesis.

Flavonoids synthesized by the phenylpropanoid pathway participate in a number of physiological an... more Flavonoids synthesized by the phenylpropanoid pathway participate in a number of physiological and biochemical processes in plants. Flavonols, among flavonoids, are considered as health-protective components in functional foods and they protect plants against certain insect pests. There have been efforts to develop strategies for the enhanced production of flavonols in plants, but limited success was achieved due to complex regulation and poor substrate availability. In the present study, we have developed and optimized method for callus cultures for transgenic tobacco line expressing a flavonol-specific transcription factor, AtMYB12, with an objective to use callus as an alternative source of rutin. Transgenic callus displayed enhanced expression of genes related to biosynthetic pathway leading to increased accumulation of flavonols, especially rutin. At each time point of callus growth, the rutin content of transgenic callus was several folds higher than that of wild-type tobacco callus. Supplementation of semi-synthetic diet with extract from transgenic callus as well as purified rutin led to mortality and growth reduction in the Spodoptera litura and Helicoverpa armigera larvae. This study suggests the biotechnological potential of AtMYB12-expressing callus cultures for the production of rutin, which can be used for biopesticide formulations against insect pests. Tobacco callus cultures expressing AtMYB12 accumulate enhanced content of rutin and can be used as a potential alternative source of rutin as well as biopesticides against insect pests.

Flavonoids synthesized by the phenylpropanoid pathway participate in myriad physiological and bio... more Flavonoids synthesized by the phenylpropanoid pathway participate in myriad physiological and biochemical processes in plants. Due to the diversity of secondary transformations and the complexity of the regulation of branched pathways, single gene strategies have not been very successful in enhancing the accumulation of targeted molecules. We have expressed an Arabidopsis (Arabidopsis thaliana) transcription factor, AtMYB12, in tobacco (Nicotiana tabacum), which resulted in enhanced expression of genes involved in the phenylpropanoid pathway, leading to severalfold higher accumulation of flavonols. Global gene expression and limited metabolite profiling of leaves in the transgenic lines of tobacco revealed that AtMYB12 regulated a number of pathways, leading to flux availability for the phenylpropanoid pathway in general and flavonol biosynthesis in particular. The tobacco transgenic lines developed resistance against the insect pests Spodoptera litura and Helicoverpa armigera due to enhanced accumulation of rutin. Suppression of flavonol biosynthesis by artificial microRNA reversed insect resistance of the AtMYB12-expressing tobacco plants. Our study suggests that AtMYB12 can be strategically used for developing safer insect pest-resistant transgenic plants.

Chemosphere, 2009

The effect of arsenic (As) exposure on genome-wide expression was examined in rice (Oryza sativa ... more The effect of arsenic (As) exposure on genome-wide expression was examined in rice (Oryza sativa L., ssp. Indica). A group of defense and stress-responsive genes, transporters, heat-shock proteins, metallothioneins, sulfate-metabolizing proteins, and regulatory genes showed ...

AGE, 2014

Dichloroacetic acid (DCA), a water disinfection by-product, has attained emphasis due to its pros... more Dichloroacetic acid (DCA), a water disinfection by-product, has attained emphasis due to its prospect for clinical use against different diseases including cancer along with negative impact on organisms. However, these reports are based on the toxicological as well clinical data using comparatively higher concentrations of DCA without much of environmental relevance. Here, we evaluate cellular as well as organismal effects of DCA at environmentally and mild clinically relevant concentrations (0.02-20.0 μg/ml) using an established model organism, Drosophila melanogaster. Flies were fed on food mixed with test concentrations of DCA for 12-48 h to examine the induction of reactive oxygen species (ROS) generation, oxidative stress (OS), heat shock genes (hsps) and cell death along with organismal responses. We also examined locomotor performance, ROS generation, glutathione (GSH) depletion, expression of GSH-synthesizing genes (gclc and gclm), and hsps at different days (0, 10, 20, 30, 40, 50) of the age in flies after prolonged DCA exposure. We observed mild OS and induction of antioxidant defense system in 20.0 μg/ml DCA-exposed organism after 24 h. After prolonged exposure to DCA, exposed organism exhibited improved survival, elevated expression of hsp27, gclc, and gclm concomitant with lower ROS generation and GSH depletion and improved locomotor performance. Conversely, hsp27 knockdown flies exhibited reversal of the above end points. The study provides evidence for the attenuation of cellular and functional decline in aged Drosophila after prolonged DCA exposure and the effect of hsp27 modulation which further incites studies towards the therapeutic application of DCA.

Very little is known about molecular events associated with callus differentiation in indica rice... more Very little is known about molecular events associated with callus differentiation in indica rice. The genes expressed differentially during shoot meristem initiation were identified on genomic arrays applied to efficiently regenerating rice calli. A thidiazuron (TDZ; N-phenyl-N-thiadiazol-1,2,3-5,ylurea)-dependent regeneration protocol was developed for efficient embryogenesis in indica rice. The regenerating embryogenic calli induced by TDZ for 10 days showed transcriptional modulation of a number of genes associated with photosynthesis, hormone metabolism, plant development, signal transduction, light response, and plant defense. Eighteen candidate miRNAs were predicted to target the genes expressed differentially in the embryogenic calli grown in TDZ-containing medium. The majority of the photosynthesis-related genes up-regulated in differentiating calli were not expressed or were down-regulated in developing seeds and inflorescences. Most of the genes down-regulated in differentiating calli were up-regulated in developing seeds. The transcriptome of differentiating callus most closely resembled that of the germinating whole seed.