Browsing by Author "Om Prakash Narayan"

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A single gene all3940 (Dps) overexpression in Anabaena sp. PCC 7120 confers multiple abiotic stress tolerance via proteomic alterations
(Springer Verlag, 2016) Om Prakash Narayan; Nidhi Kumari; Poonam Bhargava; Hema Rajaram; Lal Chand Rai
DNA-binding proteins (Dps) induced during starvation play an important role in gene regulation and maintaining homeostasis in bacteria. The nitrogen-fixing cyanobacterium, Anabaena PCC7120, has four genes annotated as coding for Dps; however, the information on their physiological roles is limiting. One of the genes coding for Dps, ‘all3940’ was found to be induced under different abiotic stresses in Anabaena and upon overexpression enhanced the tolerance of Anabaena to a multitude of stresses, which included salinity, heat, heavy metals, pesticide, and nutrient starvation. On the other hand, mutation in the gene resulted in decreased growth of Anabaena. The modulation in the levels of All3940 in Anabaena, achieved either by overexpression of the protein or mutation of the gene, resulted in changes in the proteome, which correlated well with the physiological changes observed. Proteins required for varied physiological activities, such as photosynthesis, carbon-metabolism, oxidative stress alleviation, exhibited change in protein profile upon modulation of All3940 levels in Anabaena. This suggested a direct or an indirect effect of All3940 on the expression of the above stress-responsive proteins, thereby enhancing tolerance in Anabaena PCC7120. Thus, All3940, though categorized as a Dps, is possibly a general stress protein having a global role in regulating tolerance to multitude of stresses in Anabaena. © 2015, Springer-Verlag Berlin Heidelberg.
Cyanobacterial diversity shifts induced by butachlor in selected Indian rice fields in Eastern Uttar Pradesh and Western Bihar analyzed with PCR and DGGE
(Korean Society for Microbiolog and Biotechnology, 2012) Kumari; Nidhi; Om Prakash Narayan; Lal Chand Rai
The present study examines the effects of 30 mg/kg butachlor on the cyanobacterial diversity of rice fields in Eastern Uttar Pradesh and Western Bihar in India. A total of 40 samples were grouped into three classes [(i) acidic, (ii) neutral, and (iii) alkaline soils], based on physicochemical and principle component analyses. Acidic soils mainly harbored Westillopsis, Trichormus, Anabaenopsis, and unicellular cyanobacteria; whereas Nostoc, Anabaena, Calothrix, Tolypothrix, and Aulosira were found in neutral and alkaline soils. Molecular characterization using 16S rRNA PCR and DGGE revealed the presence of 13 different phylotypes of cyanobacteria in these samples. Butachlor treatment of the soil samples led to the disappearance of 5 and the emergence of 2 additional phylotypes. A total of 40 DGGE bands showed significant reproducible changes upon treatment with butachlor. Phylogenetic analyses divided the phylotypes into five major clusters exhibiting interesting links with soil pH. Aulosira, Anabaena, Trichormus, and Anabaenopsis were sensitive to butachlor treatment, whereas uncultured cyanobacteria, a chroococcalean member, Westillopsis, Nostoc, Calothrix, Tolypothrix, Rivularia, Gloeotrichia, Fischerella, Leptolyngbya, and Cylindrospermum, appeared to be tolerant against butachlor at their native soil pH. Butachlor-induced inhibition of nitrogen fixation was found to be 65% (maximum) and 33% (minimum) in the soil samples of pH 9.23 and 5.20, respectively. In conclusion, low butachlor doses may prove beneficial in paddy fields having a neutral to alkaline soil pH.
Excess copper induces anoxygenic photosynthesis in Anabaena doliolum: A homology based proteomic assessment of its survival strategy
(2008) Poonam Bhargava; Yogesh Mishra; Ashish Kumar Srivastava; Om Prakash Narayan; Lal Chand Rai
This study is the first to demonstrate operation of anoxygenic photosynthesis in copper acclimated Anabaena doliolum and to offer proteomic comparison with the control cells. The Cu-treated control strain showed a negative correlation in growth and intracellular Cu, partial inhibition of O2-evolution, PS II, PS I, whole chain, chlorophyll absorption, and nitrogenase activity. However, the acclimated strain growing in 250-fold excess Cu exhibited near normal growth, ATP content, PS I activity, carbon fixation, and almost complete inhibition of O2-evolution, PS II and chlorophyll absorption, but increased nitrogenase activity as compared to control. Proteomic decoding of the survival strategy of Cu-treated control and the acclimated strain using two-dimensional gel electrophoresis and MALDI-TOF MS analysis of proteins displaying significant and reproducible changes demonstrated involvement of transketolase, phycoerythrocyanin α-chain, iron superoxide dismutase (Fe-SOD), hypothetical protein alr 0803, manganese superoxide dismutase (Mn-SOD), phosphoribulokinase, and plastocyanin (PLC). Expression pattern of these proteins was attested at the transcriptional level using RT-PCR. Time course analysis of proteins of Cu-treated control strain revealed almost no change in PLC level, and a minor accumulation of transketolase, phycoerythrocyanin α-chain and both isoforms of SOD after 7 and recovery after 10 days. Acclimated strain under excess Cu, however, exhibited significant accumulation of both isoforms of SOD, plastocyanin, phosphoribulokinase and transketolase, which seem to counteract oxidative damage, serve as an alternate electron carrier from cytochrome b6/f complex to photosystem I and meet the NADPH and ATP requirements, respectively, under anoxygenic photosynthesis. In view of the kinetics of the hypothetical protein alr0803 (no change in expression level for 7, maximum after 10 and decline after 15 days) its involvement in metal homeostasis is suggested. © 2007 Springer Science+Business Media B.V.
Heterologous expression of Anabaena PCC 7120 all3940 (a Dps family gene) protects Escherichia coli from nutrient limitation and abiotic stresses
(2010) Om Prakash Narayan; Nidhi Kumari; Lal Chand Rai
This study presents first hand data on the cloning and heterologous expression of Anabaena PCC 7120 all3940 (a dps family gene) in combating nutrients limitation and multiple abiotic stresses. The Escherichia coli transformed with pGEX-5X-2-all3940 construct when subjected to iron, carbon, nitrogen, phosphorus limitation and carbofuron, copper, UV-B, heat, salt and cadmium stress registered significant increase in growth over the cells transformed with empty vector under iron (0%), carbon (0.05%), nitrogen (3.7 mM) and phosphorus (2 mM) limitation and carbofuron (0.025 mg ml-1), CuCl2 (1 mM), UV-B (10 min), heat (47 °C), NaCl (6% w/v) and CdCl2 (4 mM) stress. Enhanced expression of all3940 gene measured by semi-quantitative RT-PCR at different time points under above mentioned treatments clearly demonstrates its role in tolerance against aforesaid abiotic stresses. This study opens the gate for developing transgenic cyanobacteria capable of growing successfully under above mentioned stresses. © 2010 Elsevier Inc. All rights reserved.
Understanding butachlor toxicity in Aulosira fertilissima using physiological, biochemical and proteomic approaches
(Elsevier Ltd, 2009) Nidhi Kumari; Om Prakash Narayan; Lal Chand Rai
The present study examines butachlor-induced inhibition of growth, photosynthetic pigments such as chlorophyll a, phycocyanin, allophycocyanin, phycoerythrin, photosystems I and II, whole chain electron transport, oxygen evolution, carbon fixation, ATP content, total thiol and glutathione contents of Aulosira fertilissima. For ascertaining if above mentioned changes are due to disturbance in plasma membrane integrity or proteins, fatty acid profiling and proteomics were done. Gas chromatographic (GC) analysis of fatty acid methyl esters (FAME) depicted a decrease in α-linolenic acid (C18:3) which appears responsible for plasma membrane instability. Enhanced lipid peroxidation and electrolyte leakage further attested the butachlor-induced cell damage. Butachlor-treated Aulosira exhibited significant and reproducible alternations in eight proteins as assessed by 2DE and LC-MS analysis of which phycocyanin α-chain, allophycocyanin β-chain, C-phycocyanin α-subunit, ATP synthase β-chain and FBP aldolase were associated with photosynthesis and respiration, peroxiredoxin with antioxidative defense system and GroES and NusB with protein folding and transcription termination respectively. However, a prolonged (15 d) butachlor treatment of Aulosira downregulated all the proteins except NusB. Reverse transcription PCR of the protein genes affirmed that aforesaid proteins were the gene products not artifacts. Downregulated GroES and over expressed NusB are critical proteins for cell death. © 2009 Elsevier Ltd. All rights reserved.