Browsing by Author "Brajesh Kumar Singh"

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Bifurcation analysis of modified Leslie-Gower predator-prey model with double Allee effect
(Ain Shams University, 2018) Manoj Kumar Singh; B.S. Bhadauria; Brajesh Kumar Singh
In the present article, a modified Leslie-Gower predator-prey model with double Allee effect, affecting the prey population, is proposed and analyzed. We have considered both strong and weak Allee effects separately. The equilibrium points of the system and their local stability have been studied. It is shown that the dynamics of the system are highly dependent upon the initial conditions. The local bifurcations (Hopf, saddle-node, Bogdanov-Takens) have been investigated by considering sufficient parameter(s) as the bifurcation parameter(s). The local existence of the limit cycle emerging through Hopf bifurcation and its stability is studied by means of the first Lyapunov coefficient. The numerical simulations have been done in support of the analytical findings. The result shows the emergence of homoclinic loop. The possible phase portraits and parametric diagrams have been depicted. © 2016 Ain Shams University
Biochemical and molecular mechanisms of N-acetyl cysteine and silymarin-mediated protection against maneb- and paraquat-induced hepatotoxicity in rats
(2013) Israr Ahmad; Smriti Shukla; Ashutosh Kumar; Brajesh Kumar Singh; Vinod Kumar; Amit Kumar Chauhan; Dhirendra Singh; Haushila Prasad Pandey; Chetna Singh
Oxidative stress is one of the major players in the pathogenesis of maneb (MB) and paraquat (PQ)-induced disorders. N-acetyl cysteine (NAC), a glutathione (GSH) precursor and silymarin (SIL), a naturally occurring antioxidant, encounter oxidative stress-mediated cellular damage. The present study was aimed to investigate the effects of NAC and SIL against MB and/or PQ-induced hepatotoxicity in rats. The levels of hepatotoxicity markers-alanine aminotransaminase (ALT), aspartate aminotransaminase (AST) and total bilirubin, histological changes, oxidative stress indices, phase I and phase II xenobiotic metabolizing enzymes-cytochrome P450 (CYP) and glutathione S-transferase (GST) and pro-inflammatory molecules-inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were measured in animals treated with MB and/or PQ in the presence or absence of NAC and SIL. MB and/or PQ augmented ALT, AST, total bilirubin, lipid peroxidation and nitrite contents and catalytic activities of superoxide dismutase and glutathione peroxidase however, the GSH content was attenuated. NAC and SIL restored the above-mentioned alterations towards basal levels but the restorations were more pronounced in SIL treated groups. Similarly, MB and/or PQ-mediated histopathological symptoms and changes in the catalytic activities/expressions of CYP1A2, CYP2E1, iNOS, TNF-α, and IL-1β were alleviated by NAC and SIL. Conversely, MB and/or PQ-induced GSTA4-4 expression/activity was further increased by NAC/SIL and glutathione reductase activity was also increased. The results obtained thus suggest that NAC and SIL protect MB and/or PQ-induced hepatotoxicity by reducing oxidative stress, inflammation and by modulating xenobitic metabolizing machinery and SIL seems to be more effective. © 2013 Elsevier Ireland Ltd. All rights reserved.
Correction to: CYP2E1-mediated oxidative stress regulates HO-1 and GST expression in maneb- and paraquat-treated rat polymorphonuclear leukocytes (Molecular and Cellular Biochemistry, (2014), 393, 1-2, (209-222), 10.1007/s11010-014-2062-y)
(Springer New York LLC, 2019) Israr Ahmad; Smriti Shukla; Deepali Singh; Amit Kumar Chauhan; Vinod Kumar; Brajesh Kumar Singh; Devendra Kumar Patel; Haushila Prasad Pandey; Chetna Singh
In the original publication of the article, the wrong β-actin blots were pasted in Figs. 1b and 2c. The correct versions of Figs. 1b and 2c are given in this correction. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.
CYP2E1-mediated oxidative stress regulates HO-1 and GST expression in maneb- and paraquat-treated rat polymorphonuclear leukocytes
(Kluwer Academic Publishers, 2014) Israr Ahmad; Smriti Shukla; Deepali Singh; Amit Kumar Chauhan; Vinod Kumar; Brajesh Kumar Singh; Devendra Kumar Patel; Haushila Prasad Pandey; Chetna Singh
Cytochrome P4502E1 (CYP2E1), glutathione-S-transferase A4-4 (GSTA4-4), and inducible nitric oxide synthase (iNOS) are implicated in maneb- and paraquat-induced toxicity leading to various pathological conditions. The study aimed to investigate the role of CYP2E1 in maneb- and paraquat-induced oxidative stress in rat polymorphonuclear leukocytes (PMNs) and its crosstalk with iNOS-mediated nitrosative stress and GSTA4-4-linked protective effect, if any and their consequent links with the nuclear factor erythoid 2-related factor 2 (Nrf2) activation and heme oxygenase-1 (HO-1) expression. Rats were treated with/without maneb and/or paraquat for 1, 2, and 3 weeks along with vehicle controls. Subsets of rats were also treated with diallyl sulfide (DAS) or aminoguanidine (AG) along with the respective controls. Maneb and paraquat augmented the reactive oxygen species (ROS), lipid peroxidation (LPO) and 4-hydroxy nonenal (4-HNE) contents, and superoxide dismutase (SOD) activity in the PMNs. However, maneb and paraquat attenuated the reduced glutathione (GSH) level and the expression/activity of total GST and GST-pi. Maneb and paraquat increased the expression/activity of CYP2E1, GSTA4-4, iNOS, Nrf2 and HO-1, and nitrite content. CYP2E1 inhibitor, DAS noticeably alleviated maneb- and paraquat-induced ROS, LPO, 4-HNE, SOD, Nrf2 and HO-1, GST, GSH, and GST-pi while iNOS, nitrite content and GSTA4-4 levels were unchanged. Conversely, AG, an iNOS inhibitor, attenuated maneb- and paraquat-directed changes in nitrite, LPO, iNOS but it did not alter ROS, GSH, SOD, GST, GST-pi, Nrf2, HO-1, CYP2E1, and GSTA4-4. The results demonstrate that CYP2E1 induces iNOS-independent free radical generation and subsequently modulates the Nrf2-dependent HO-1 and 4-HNE-mediated GST expression in maneb- and paraquat-treated PMNs. © 2014 Springer Science+Business Media.
Effect of zinc and paraquat co-exposure on neurodegeneration: Modulation of oxidative stress and expression of metallothioneins, toxicant responsive and transporter genes in rats
(2010) Ashutosh Kumar; Israr Ahmad; Smriti Shukla; Brajesh Kumar Singh; Devendra Kumar Patel; Haushila Prasad Pandey; Chetna Singh
Oxidative stress is implicated in Parkinson's disease (PD). Metallothioneins (MT), cytochrome P450 IIE1 (CYP2E1) and glutathione S-transferases alpha4-4 (GSTA4-4) are involved in oxidative stress-mediated damage. Altered dopamine transporter (DAT) and vesicular monoamine transporter-2 (VMAT-2) are also documented in PD. The present study was undertaken to investigate the effect of Zn and PQ co-exposure on neurodegeneration in rats. A significant reduction was observed in spontaneous locomotor activity (SLA), striatal dopamine (DA) levels, tyrosine hydroxylase (TH) immunoreactivity, glutathione reductase (GR) and catalase activity along with increased lipid peroxidation (LPO) and glutathione peroxidase (GPx) activity after Zn and/or PQ exposure. Zn and/or PQ exposure increased gene expression of DAT, CYP2E1, GSTA4-4, MT-I and MT-II, but reduced the expression of VMAT-2. Protein expression analysis of TH, VMAT-2 and DAT showed results similar to those obtained with gene expression study. Zn and PQ co-exposure caused a more pronounced effect than that of individual exposure. The results obtained in this study suggest that, similar to PQ, Zn induced neurodegeneration via alterations in oxidative stress and expression of the above-mentioned genes. However, the effect of ZnPQ was only slightly higher than that of alone, indicating that probably Zn and PQ follow some different molecular events leading to neurodegeneration. © 2010 Informa UK Ltd.
Harnessing chickpea (Cicer arietinum L.) seed endophytes for enhancing plant growth attributes and bio-controlling against Fusarium sp.
(Elsevier GmbH, 2020) Arpan Mukherjee; Brajesh Kumar Singh; Jay Prakash Verma
A seed microbiome is likely to have important impacts on plant fitness and productivity but functional potentials of seed microbiome remain poorly understood. It is also suggested that bio-inoculants developed from or compatible with seed microbiome are more likely to produce desired outcomes of sustainable increase in agriculture productivity but few empirical evidences are available. The aim of this study was to identify culturable endophytes of the germinating and dry seeds of chickpea (Cicer arietinum L.), and their functional attributes. We isolated 29 bacterial strains from chickpea seeds (8 strains from dry and 21 strains from germinating seeds). Phylogenetic analysis based on 16S rDNA showed that the seed endophytic bacteria belong to Enterobacter sp., Bacillus sp., Pseudomonas sp., Staphylococcus sp., Pantoea sp. and Mixta sp. Isolates produced significant amount of Indole-3-acetic acid (IAA) (Enterobacter hormaechei BHUJPCS-15; 58.91 μg/ml), solubilised phosphate (Bacillus subtilis BHUJPCS-24; 999.85 μg/ml) and potassium, ammonia (Bacillus subtilis BHUJPCS-12; 148.73 μg/ml), and also inhibited the growth of chickpea pathogen (Pseudomonas aeruginosa BHUJPCS-7 against Fusarium oxysporum f.sp. ciceris) under laboratory conditions. Several seed endophytes induced significant increase in plant growth and increased tolerance of chickpea plants to the pathogen (Fusarium oxysporum f.sp. ciceris) when tested in vitro. Re-introduction of these isolates, resulted in significant increase in plant length, biomass and chlorophyll contents and bio-controlling activity against Fusarium oxysporum f.sp. ciceris. These results provide a direct evidence for the presence of beneficial seed microbiome and suggest these isolates could be further developed into potential bio-inoculants for improving diseases management and sustainable increase in agriculture productivity. © 2020 Elsevier GmbH
Involvement of NADPH oxidase and glutathione in zinc-induced dopaminergic neurodegeneration in rats: Similarity with paraquat neurotoxicity
(2012) Ashutosh Kumar; Brajesh Kumar Singh; Israr Ahmad; Smriti Shukla; Devendra Kumar Patel; Garima Srivastava; Vinod Kumar; Haushila Prasad Pandey; Chetna Singh
An association between excessive zinc (Zn) accumulation in brain and incidences of Parkinson's disease (PD) has been shown in several epidemiological and experimental investigations. The involvement of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and glutathione (GSH) in the pathogenesis of PD has also been proposed in a few studies. Despite the implicated role of oxidative stress in PD, the entire mechanism of Zn-induced dopaminergic neurodegeneration has not yet been clearly understood. The present study aimed to investigate the involvement of NADPH oxidase and GSH in Zn-induced dopaminergic neurodegeneration and also to assess its similarity with paraquat (PQ)-induced rat model of PD. Male Wistar rats were treated either with Zn (20 mg/kg; i.p.) or PQ (5 mg/kg; i.p.) in the presence and absence of NADPH oxidase inhibitor, apocynin (10 mg/kg; i.p.) and a GSH precursor, N-acetyl cysteine (NAC; 200 mg/kg; i.p.) either alone or in combination along with the respective controls. Apocynin and/or NAC pre-treatment significantly alleviated Zn- and PQ-induced changes in neurobehavioral deficits, number of dopaminergic neurons and contents of the striatal dopamine and its metabolites. Apocynin and/or NAC also mitigated Zn- and PQ-induced alterations in oxidative stress, NADPH oxidase activation and cytochrome c release, caspases-9 and -3 activation and CD11b expression. The results obtained thus suggest that Zn induces oxidative stress via the activation of NADPH oxidase and depletion of GSH, which in turn activate the apoptotic machinery leading to dopaminergic neurodegeneration similar to PQ. © 2011 Elsevier B.V. All rights reserved.
Maneb and paraquat-induced modulation of toxicant responsive genes in the rat liver: Comparison with polymorphonuclear leukocytes
(2010) Israr Ahmad; Smriti Shukla; Ashutosh Kumar; Brajesh Kumar Singh; Devendra Kumar Patel; Haushila Prasad Pandey; Chetna Singh
Experimental studies have shown that toxicant responsive genes, cytochrome P450s (CYPs) and glutathione S-transferases (GSTs) play a critical role in pesticide-induced toxicity. CYPs play pro-oxidant role and GSTs offer protection in maneb (MB) and paraquat (PQ)-induced brain and lung toxicities. The present study aimed to investigate the effect of repeated exposures of MB and/or PQ on lipid peroxidation (LPO), glutathione content (GSH) and toxicant responsive genes, i.e., CYP1A1, 1A2, 2E1, GSTA4-4, GSTA1-1 and GSTA3-3 in the liver and to correlate the same with polymorphonuclear leukocytes (PMNs). A significant augmentation in LPO and reduction in GSH content was observed in a time of exposure dependent manner in the liver and PMNs of MB and/or PQ treated animals. The expression and catalytic activity of CYP2E1 and GSTA4-4 were significantly increased following MB and/or PQ exposure both in the liver and PMNs. Although the expression of GSTA3-3 was increased, the expression of GSTA1-1 was unaltered after MB and/or PQ treatment in both the liver and PMNs. MB augmented the expression and catalytic activity of CYP1A1 in the liver, however, CYP1A2 was unaffected. PQ, on the other hand, significantly increased hepatic CYP1A2 expression and catalytic activity. MB and/or PQ did not produce any significant changes in CYP1A1 and CYP1A2 in PMNs. The results of the study thus demonstrate that MB and PQ differentially regulate hepatic CYP1A1 and CYP1A2 while LPO, GSH, CYP2E1, GSTA4-4 and GSTA3-3 are modulated in the similar fashions both in the liver and PMNs. © 2010 Elsevier Ireland Ltd.
Phytomicrobiome for promoting sustainable agriculture and food security: Opportunities, challenges, and solutions
(Elsevier GmbH, 2021) Gowardhan Kumar Chouhan; Jay Prakash Verma; Durgesh Kumar Jaiswal; Arpan Mukherjee; Saurabh Singh; Arthur Prudêncio de Araujo Pereira; Hongwei Liu; Elsayed Fathi Abd_Allah; Brajesh Kumar Singh
Ensuring food security in an environmentally sustainable way is a global challenge. To achieve this agriculture productivity requires increasing by 70 % under increasingly harsh climatic conditions without further damaging the environmental quality (e.g. reduced use of agrochemicals). Most governmental and inter-governmental agencies have highlighted the need for alternative approaches that harness natural resource to address this. Use of beneficial phytomicrobiome, (i.e. microbes intimately associated with plant tissues) is considered as one of the viable solutions to meet the twin challenges of food security and environmental sustainability. A diverse number of important microbes are found in various parts of the plant, i.e. root, shoot, leaf, seed, and flower, which play significant roles in plant health, development and productivity, and could contribute directly to improving the quality and quantity of food production. The phytomicrobiome can also increase productivity via increased resource use efficiency and resilience to biotic and abiotic stresses. In this article, we explore the role of phytomicrobiome in plant health and how functional properties of microbiome can be harnessed to increase agricultural productivity in environmental-friendly approaches. However, significant technical and translation challenges remain such as inconsistency in efficacy of microbial products in field conditions and a lack of tools to manipulate microbiome in situ. We propose pathways that require a system-based approach to realize the potential to phytomicrobiome in contributing towards food security. We suggest if these technical and translation constraints could be systematically addressed, phytomicrobiome can significantly contribute towards the sustainable increase in agriculture productivity and food security. © 2021 Elsevier GmbH
Shifts on archaeal community structure in pure and mixed Eucalyptus grandis and Acacia mangium plantations
(Elsevier B.V., 2021) Maiele Cintra Santana; Arthur Prudêncio de Araujo Pereira; Adijailton José de Souza; Maurício Rumenos Guidetti Zagatto; Victor Lucas Vieira Prudêncio de Araújo; Jun-Tao Wang; Jay Prakash Verma; Brajesh Kumar Singh; Elke Jurandy Bran Nogueira Cardoso
Archaeal community has important contributors to nutrient cycling in the forest ecosystems. However, how soil-litter attributes shift their community structure remains poorly understood. To date, the structure of the archaeal community has never been reported either in pure or in mixed eucalypt and acacia plantations, especially in tropical soils. Here, we analyzed the archaeal community and performed correlations with C, N and P attributes in soil-litter layers of pure Eucalyptus grandis without (E) and with N fertilization (E + N), a mixed system of E. grandis and Acacia mangium (E + A), and a pure A. mangium (A) plantation. We extracted DNA from soil (0–20 cm) and litter samples at 27 and 39 months after planting and sequenced the archaeal 16S rRNA gene. We also analyzed the abundance of 16S rRNA and amoA genes by quantitative PCR and assessed the correlations between molecular data with soil-litter attributes (i.e., microbial and enzyme activities, and C, N and P contents). The high-throughput sequencing of the archaeal 16S rRNA gene revealed that the treatments influenced the archaeal community structure. However, the litter layer showed more significant modifications, since archaeal richness, diversity, and the relative abundance of Thaumarchaeota increased in the litter of pure acacia and mixed treatments at both, 27 and 39 months after planting. There was no clear pattern regarding the abundance of functional genes in the soil, but archaeal structure responded to treatments in the litter layer, in which NH4+, total-N and the C/N ratio were the most important attributes for community group differentiation. Our study provides novel insights into the structure and function of archaea in pure and mixed forest systems, but highlights that young mixed plantations exert a low effect on soil community structure. Archaeal community may have an important role in nutrient cycling in the litter interface, especially related to the N cycle in the initial stages of tree development. © 2021 Elsevier B.V.