Browsing by Author "Alok Kumar Shrivastava"

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A novel alkyl hydroperoxidase (AhpD) of Anabaena PCC7120 confers abiotic stress tolerance in Escherichia coli
(Springer Verlag, 2015) Alok Kumar Shrivastava; Shilpi Singh; Prashant Kumar Singh; Sarita Pandey; L.C. Rai
In silico analysis together with cloning, molecular characterization and heterologous expression reports that the hypothetical protein All5371 of Anabaena sp. PCC7120 is a novel hydroperoxide scavenging protein similar to AhpD of bacteria. The presence of E(X)11CX HC(X)3H motif in All5371 confers peroxidase activity and closeness to bacterial AhpD which is also reflected by its highest 3D structure homology with Rhodospirillum rubrum AhpD. Heterologous expression of all5371 complimented for ahpC and conferred resistance in MJF178 strain (ahpCF::Km) of Escherichia coli. All5371 reduced the organic peroxide more efficiently than inorganic peroxide and the recombinant E. coli strain following exposure to H2O2, CdCl2, CuCl2, heat, UV-B and carbofuron registered increased growth over wild-type and mutant E. coli transformed with empty vector. Appreciable expression of all5371 in Anabaena sp. PCC7120 as measured by qRT-PCR under selected stresses and their tolerance against H2O2, tBOOH, CuOOH and menadione attested its role in stress tolerance. In view of the above, All5371 of Anabaena PCC7120 emerged as a new hydroperoxide detoxifying protein. © 2014, Springer-Verlag Berlin Heidelberg.
Advances in Cyanobacterial Biology
(Elsevier, 2020) Prashant Kumar Singh; Ajay Kumar; Vipin Kumar Singh; Alok Kumar Shrivastava
Advances in Cyanobacterial Biology presents the novel, practical, and theoretical aspects of cyanobacteria, providing a better understanding of basic and advanced biotechnological application in the field of sustainable agriculture. Chapters have been designed to deal with the different aspects of cyanobacteria including their role in the evolution of life, cyanobacterial diversity and classification, isolation, and characterization of cyanobacteria through biochemical and molecular approaches, phylogeny and biogeography of cyanobacteria, symbiosis, Cyanobacterial photosynthesis, morphological and physiological adaptation to abiotic stresses, stress-tolerant cyanobacterium, biological nitrogen fixation. Other topics include circadian rhythms, genetics and molecular biology of abiotic stress responses, application of cyanobacteria and cyanobacterial mats in wastewater treatments, use as a source of novel stress-responsive genes for development of stress tolerance and as a source of biofuels, industrial application, as biofertilizer, cyanobacterial blooms, use in Nano-technology and nanomedicines as well as potential applications. This book will be important for academics and researchers working in cyanobacteria, cyanobacterial environmental biology, cyanobacterial agriculture and cyanobacterial molecular biologists. © 2020 Elsevier Inc. All rights reserved.
Alr0882 encoding a hypothetical protein of Anabaena PCC7120 protects Escherichia coli from nutrient starvation and abiotic stresses
(2012) Alok Kumar Shrivastava; Sarita Pandey; Prashant Kumar Singh; Snigdha Rai; Lal Chand Rai
This study is the first to demonstrate cloning of alr0882, a hypothetical protein gene of Anabaena PCC7120, its heterologous expression in Escherichia coli strain LN29MG1655 (uspA::Kan) and functional complementation of abiotic stress tolerance of E. coli UspA. The recombinant vector pGEX-5X-2-alr0882 was used to transform uspA E. coli strain. The IPTG induced expression of a 56.6kDa GST fusion protein was visualized on SDS-PAGE and attested by immunoblotting. E. coli uspA strain harboring pGEX-5X-2-alr0882 when grown under carbon, nitrogen, phosphorus and sulphur limitation and abiotic stresses e.g. nalidixic acid, cycloserine, CdCl2, H2O2, UV-B, phenazine methosulphate (PMS), dinitrophenol (DNP), NaCl, heat, carbofuron and CuCl2 demonstrated about 22.6-51.6% increase in growth over the cells transformed with empty vector. Expression of alr0882 gene in mutant E. coli as measured by semi-quantitative RT-PCR at different time points under selected treatments reaffirmed its role in tolerance against stresses employed in this study. Thus the results of this study vividly demonstrated that the novel protein alr0882, although appreciably different from the known UspA of E. coli, offers tolerance to abiotic stresses hence holds potential for the development of transgenic cyanobacteria. © 2012 Elsevier B.V.
Alr2954 of Anabaena sp. PCC 7120 with ADP-ribose pyrophosphatase activity bestows abiotic stress tolerance in Escherichia coli
(Springer Verlag, 2017) Prashant Kumar Singh; Alok Kumar Shrivastava; Shilpi Singh; Ruchi Rai; Antra Chatterjee; L.C. Rai
In silico derived properties on experimental validation revealed that hypothetical protein Alr2954 of Anabaena sp. PCC7120 is ADP-ribose pyrophosphatase, which belongs to nudix hydrolase superfamily. Presence of ADP-ribose binding site was attested by ADP-ribose pyrophosphatase activity (Km 44.71 ± 8.043 mM, Vmax 7.128 ± 0.417 μmol min−1 mg protein−1, and Kcat/Km 9.438 × 104 μM−1 min−1). Besides ADP-ribose, the enzyme efficiently hydrolyzed various nucleoside phosphatases such as 8-oxo-dGDP, 8-oxo-dADP, 8-oxo-dGTP, 8-oxo-dATP, GDP-mannose, ADP-glucose, and NADH. qRT-PCR analysis of alr2954 showed significant expression under different abiotic stresses reconfirming its role in stress tolerance. Thus, Alr2954 qualifies to be a member of nudix hydrolase superfamily, which serves as ADP-ribose pyrophosphatase and assists in multiple abiotic stress tolerance. © 2016, Springer-Verlag Berlin Heidelberg.
Cadmium toxicity in diazotrophic Anabaena spp. adjudged by hasty up-accumulation of transporter and signaling and severe down-accumulation of nitrogen metabolism proteins
(Elsevier, 2015) Prashant Kumar Singh; Alok Kumar Shrivastava; Antra Chatterjee; Sarita Pandey; Snigdha Rai; Shilpi Singh; L.C. Rai
Present study demonstrates interspecies variation in proteome and survival strategy of three Anabaena species i.e., Anabaena L31, Anabaena sp. PCC 7120 and Anabaena doliolum subjected to respective LC50 doses of Cd at 0, 1, 3, 5 and 7day intervals. The proteome coverage with 452 differentially accumulated proteins unveiled species and time specific expression and interaction network of proteins involved in important cellular functions. Statistical analysis of protein abundance across Cd-treated proteomes clustered their co-expression pattern into four groups viz., (i) early (days 1 and 3) accumulated proteins, (ii) proteins up-accumulated for longer duration, (iii) late (days 5 and 7) accumulated proteins, and (iv) mostly down-accumulated proteins. Appreciable growth of Cd treated A L31 over other two species may be ascribed to proteins contained in the first and second groups (belonging to energy and carbohydrate metabolism (TK, G6-PI, PGD, FBA, PPA, ATP synthase)), sulfur metabolism (GR, GST, PGDH, PAPS reductase, GDC-P, and SAM synthetase), fatty acid metabolism (AspD, PspA, SQD-1), phosphorous metabolism (PhoD, PstB and SQD1), molecular chaperones (Gro-EL, FKBP-type peptidylprolyl isomerase), and antioxidative defense enzymes (SOD-A, catalase). Anabaena sp. PCC 7120 harboring proteins largely from the third group qualified as a late accumulator and A. doliolum housing majority of proteins from the fourth group emerged as the most sensitive species. Thus early up-accumulation of transporter and signaling category proteins and drastic reduction of nitrogen assimilation proteins could be taken as a vital indicator of cadmium toxicity in Anabaena spp. This article is part of a Special Issue entitled: Proteomics in India. © 2015 .
Cadmium-mediated morphological, biochemical and physiological tuning in three different Anabaena species
(Elsevier B.V., 2018) Prashant Kumar Singh; Wenjing Wang; Alok Kumar Shrivastava
Cyanobacteria are a natural inhabitant of paddy field and enhance the crop productivity in an eco-friendly manner. Cadmium (Cd) is a perilous trace metal element which not only limits the crop productivity but also inhibits the growth and nitrogen-fixing ability of these diazotrophs as well as the biodiversity of rice field semiaquatic agroecosystems. However, the impact of Cd toxicity in diazotrophic cyanobacteria is yet not adequately addressed. Therefore, in the present study, three diazotrophic cyanobacterial species, i.e., Anabaena sp. PCC7120, Anabaena L31, and Anabaena doliolum were subjected to their LC50 doses of Cd, and their physiological (PSII, Psi, respiration, energy status and nitrogen fixation rate), biochemical variables (such as antioxidant contents and antioxidant enzymes) together with morphological parameters were evaluated. The results of physiological variables suggested that the Cd exposure adversely affects the photosynthesis, respiration, and biological nitrogen fixation ability across three Anabaena species. The results of biochemical variables in terms of accumulation of antioxidants (glutathione, thiol, phytochelatin and proline) content as well as antioxidant enzymes such as glutathione S-transferase (GST), glutathione reductase (GR), catalase-peroxidase (CAT), ascorbate peroxidase (APX) and superoxide dismutase (SOD) revealed that their inter-species stress tolerance behavior may be attributed to the differential accumulation of antioxidants as well as differential antioxidant enzyme activity in three species. Furthermore, the enhanced antioxidant enzymes activity such as GST, GR, CAT, and SOD in Anabaena L31 advocated significantly higher as compared to Anabaena PCC7120 and Anabaena doliolum. In conclusion, Cd-toxicity assessment regarding physiological, biochemical and morphological aspects across three species identified Anabaena L31 as Cd-resistant species than the other two tested species, i.e., Anabaena PCC7120 and Anabaena doliolum. © 2018 Elsevier B.V.
Comparative proteomics unveils cross species variations in Anabaena under salt stress
(Elsevier B.V., 2014) Snigdha Rai; Chhavi Agrawal; Alok Kumar Shrivastava; Prashant Kumar Singh; L.C. Rai
The present study compares protein diversity within three Anabaena species (Anabaena doliolum, Anabaena sp.PCC 7120 and Anabaena L31). 2-DE based analysis of 256 protein spots in control and 1, 3, 5, and 7days of salt treatment resulted into 96 proteins arching across fourteen functional categories were assigned to biochemical pathways using KOBAS 2.0. While 52.34% of the evaluated protein spots were common across three species, the remaining 47.66% fraction mainly comprised of the hypothetical and unknown proteins. PSORTb, CDD, Motifscan and Pfam revealed function and subcellular localization for 27 of the 31 hypothetical and unknown proteins. The differences in high salt tolerance (LC50) of A. doliolum over A. L31 was reflected by (i) many fold accumulation (as spot volumes) of Alr3090, Alr0803, peptidyl prolyl cis-trans isomerase and modulator of DNA gyrase proteins, and (ii) a better photosynthesis and energy homeostasis as indicated through photosystem activity, respiration, ATP and NADPH contents. Some common noteworthy salt effects include (i) photosystem damage, (ii) DNA damage repair, (iii) upregulated protein synthesis, (iv) enhanced sulphur metabolism, and (v) upregulated pentose phosphate pathway. 34 of the identified protein spots are novel entries to the Anabaena salt proteome. This study reveals the existence of separate strategies even within species to combat stress. Biological significance: This study for the first time enumerates protein diversity in three Anabaena species employing their presence/absence and relative abundance. Proteomics integrated with physiology and bioinformatics deciphers differential salt tolerance among the studied species and is the first of its kind to predict the function of hypothetical and unknown proteins. Salt-induced proteomic alterations clearly demonstrate significant metabolic shifts and existence of separate molecular phenome among the species investigated. This may be responsible for niche specificity limiting their application as biofertilizer. Of the 96 identified proteins, a large chunk are new entries to the Anabaena salt proteome while some protein genes may be used as potential candidates for engineering salt tolerant cyanobacteria. © 2014 Elsevier B.V.
Cyanobacteria as a source of nanoparticles and their applications
(Elsevier, 2019) Snigdha Rai; Wang Wenjing; Alok Kumar Shrivastava; Prashant Kumar Singh
Nanoparticles (NPs) are considered to improve and even revolutionize medicine, optics, and electronics. Most of the physical and chemical processes for NP synthesis require the use of toxic solvents, generation of hazardous byproducts, and high energy consumption. These shortcomings make the biological synthesis a preferred option. Biosynthesis of NPs using cyanobacteria has emerged as a rapidly developing research area in green nanotechnology; selecting the best species and optimizing the reaction conditions are under constant research. NPs can be synthesized from cyanobacteria using cell extracts or induced intracellular synthesis and naturally released in the culture medium. The naturally released NPs are stabilized by algal polysaccharides, which allows easy recovery of NPs. The size of the recovered particles as well as the reaction yield depends on the cyanobacteria genus. This chapter provides a broad understanding of NPs, highlights the disadvantages of conventional synthesis methods and includes evidence that biosynthesized NPs are better for a sustainable environment and has massive scope for pharmaceutical industries and biomedical applications. © 2019 Elsevier Inc. All rights reserved.
Cyanobacterial genome editing toolboxes: recent advancement and future projections for basic and synthetic biology researches
(Elsevier, 2020) Sandeep Kumar Singh; Alok Kumar Shrivastava; Ajay Kumar; Vipin Kumar Singh; Deepanker Yadav; Arpan Modi; Wenjing Wang; Avinash Singh; Toolika Singh; Viji Sitther; Prashant Kumar Singh
Cyanobacteria are ancient photosynthetic prokaryotes and serve as a model organism for studies such as photosynthesis and earth elements cycling. Cyanobacteria also termed microbial cell factories, because of their ability to utilize carbon dioxide, as well as sunlight absorption in one way, act as primary producers of the aquatic ecosystem while on the other way the diazotrophic forms fix atmospheric nitrogen in paddy fields. Moreover, the successful invention of several fuels as well as fine chemicals from cyanobacteria is indicative of the advancement in synthetic cyanobacteriology in one hand while on the other knocking the door of the augmented application shortly. Unfortunately, the limited availability of genetic manipulation tools for either at single-gene level or pathway to the whole genome in cyanobacteria compared to other organisms handicaps the fundamental biology researches as well as further application and advancement in synthetic cyanobacteriology. However, the role of genetic tools in tuning gene expression, genome-wide manipulations, and carbon flux redirections is available in cyanobacteria. Furthermore, recently a noteworthy headway evolving to familiarizing novel and efficient genetic manipulations tools such as riboswitches, promoters, ribosome-binding site engineering, small RNA regulatory tools, genome-scale modeling strategies, and clustered regularly interspaced short palindromic repeats-associated nuclease has revolutionized the cyanobacteriology. The present chapter disapprovingly recapitulates the recent advancement on the applications and development as well as technical limitations also for the future projections of the toolboxes for genetic manipulation of cyanobacterial genes/genomes. Besides this, the chapter also briefly discusses the toolkits feasible for large-scale cultivation of cyanobacteria. © 2020 Elsevier Inc. All rights reserved.
Cyanobacterial peroxiredoxins and their role in cyanobacterial stress biology
(Elsevier, 2020) Alok Kumar Shrivastava; Prashant Kumar Singh; Viji Sitther; Shilpi Singh; Sonam Srivastava
Peroxiredoxins (Prxs), a type of enzymatic antioxidants, are central elements of the defense system. It is a dithiol–disulfide redox regulatory network for all living life-forms. Prxs utilize a thiol-based catalytic mechanism to detoxify the ROS (reactive oxygen species), RNS (reactive nitrogen species), and RSS (reactive sulfur species) such as hydrogen peroxide, alkyl hydroperoxides, and peroxynitrite. In blue-green algae (cyanobacteria), Prxs exist in 2-Cys Prx, 1-Cys Prx, PrxQ, and type II Prx forms. The catalytic cycle of peroxiredoxin consists of three steps: (1) peroxidative reduction, (2) resolving step, and (3) reduction by using various electron donors such as ascorbic acid, thioredoxins, cyclophilins, glutathione, and glutaredoxins depending upon the organisms and types of Prxs. Prx proteins of cyanobacterium undergo conformational changes independent of their redox state. Prxs not only alter cellular ROS and RNS-dependent signaling, but depending on the Prx type, they also sense the redox state and transmit redox information to binding partners, and function as a chaperone. They serve in the context of photosynthesis and respiration, but also in metabolism and development. This chapter surveys the current literature and attempts a mostly comprehensive coverage of present-day knowledge as well as concepts on the mechanism, regulation, and function of Prx and thus on the whole Prx systems in cyanobacteria. © 2020 Elsevier Inc. All rights reserved.
Decoding the role of hypothetical protein All3255 of Anabaena PCC7120 in heavy metal stress management in Escherichia coli
(Springer Verlag, 2018) Prashant Kumar Singh; Mengmeng Tang; Sudhir Kumar; Alok Kumar Shrivastava
Cadmium is a non-essential toxic heavy metal for organisms, including plants and cyanobacteria. Cadmium resistance transporters involved in resistance of cells against various toxicants such as drugs and effluxes cytotoxic compounds from cells. However, cadmium resistance-associated protein (CadD) has never been reported from a diazotrophic cyanobacterium Anabaena sp. To test whether the hypothetical protein All3255 of Anabaena sp. PCC7120 a homolog of cadmium resistance-associated protein (CadD) involved in cadmium or heavy metal resistance or not, cloning and heterologous expression analysis of all3255 performed in Escherichia coli BL21 (DE3). Our results revealed that the strain transformed with pGEX-5X-2 + all3255 showed resistant towards not only to cadmium but also other heavy metals such as nickel, copper, zinc, lead and cobalt in addition to arsenic than those of transformed with empty vector (pGEX-5X-2). Furthermore, the results of metal accumulation analysis of these cells unveil a lower accumulation of tested heavy metals in all3255-overexpressing E. coli cells than those transformed with empty vector. This study strongly supports the role of All3255 of Anabaena sp. PCC7120 as a CadD efflux pump of heavy metals in E.coli. © 2017, Springer-Verlag GmbH Germany, part of Springer Nature.
In silico and wet-lab study revealed cadmium is the potent inhibitor of HupL in Anabaena sp. PC C 7120
(Springer Verlag, 2016) Shilpi Singh; Alok Kumar Shrivastava
The hupL of Anabaena sp. PCC 7120 encodes the large subunit of uptake hydrogenase found in all diazotrophic cyanobacteria and boosts up the nitrogen-fixing potential by catalyzing the removal of the molecular hydrogen produced as a by-product of dinitrogen fixation. Bioinformatics analysis revealed that HupL from Anabaena sp. PCC7120 is a 60.2 kDa, thermostable, glycine-rich protein having highest structural similarity with NiFeSe hydrogenase of Desulfomicrobium baculatumis. Toxicity of selected abiotic stresses like arsenic, cadmium, copper, and salt with HupL was further reconciled by wet-lab approaches like qRT-PCR, hydrogenase and nitrogenase activity assay as hydrogenases unintendedly affect the nitrogenase activity in Anabaena. Down-regulated transcript along with highly inhibited hydrogenase and nitrogenase activities under cadmium stress revealed that cadmium is a potent inhibitor of hydrogenases in Anabaena which indirectly affects its nitrogen-fixing capabilities. © 2015, Springer-Verlag Berlin Heidelberg.
In silico characterization and transcriptomic analysis of nif family genes from Anabaena sp. PCC7120
(Springer Netherlands, 2017) Shilpi Singh; Alok Kumar Shrivastava
In silico approaches in conjunction with morphology, nitrogenase activity, and qRT-PCR explore the impact of selected abiotic stressor such as arsenic, salt, cadmium, copper, and butachlor on nitrogen fixing (nif family) genes of diazotrophic cyanobacterium Anabaena sp. PCC7120. A total of 19 nif genes are present within the Anabaena genome that is involved in the process of nitrogen fixation. Docking studies revealed the interaction between these nif gene-encoded proteins and the selected abiotic stressors which were further validated through decreased heterocyst frequency, fragmentation of filaments, and downregulation of nitrogenase activity under these stresses indicating towards their toxic impact on nitrogen fixation potential of filamentous cyanobacterium Anabaena sp. PCC7120. Another appealing finding of this study is even though having similar binding energy and similar interacting residues between arsenic/salt and copper/cadmium to nif-encoded proteins, arsenic and cadmium are more toxic than salt and copper for nitrogenase activity of Anabaena which is crucial for growth and yield of rice paddy and soil reclamation. © 2017, Springer Science+Business Media Dordrecht.
Overexpression of AhpC enhances stress tolerance and N2–fixation in Anabaena by upregulating stress responsive genes
(Elsevier B.V., 2016) Alok Kumar Shrivastava; Sarita Pandey; Karl Josef Dietz; Prashant Kumar Singh; Shilpi Singh; Ruchi Rai; Lal Chand Rai
The study explores the significance of peroxides in regulating the CO2- and N2-fixation capacities in Anabaena sp. PCC7120. To this end Anabaena strains were generated carrying an extra copy of ahpC (An + ahpC) or by deleting from their endogenous functional ahpC (AnΔahpC). AhpC levels were 2.2- to 6.0-fold higher in An + ahpC than in wild type. An + ahpC revealed 1.4- to 2-fold upregulation of photosystems I and II, nitrogenase, superoxide dismutase and catalase activities while same activities were 1.3- to 2.5-fold downregulated in the insertional mutant (AnΔahpC) compared to the wild type. Peroxide, superoxide and malondialdehyde contents were low in An + ahpC and high in AnΔahpC. Growth was inhibited in AnΔahpC by approximately 40–60% compared to a 33–40% enhanced growth in An + ahpC under selected stresses. Most interestingly, heterocyst frequency was increased in An + ahpC. In order to address transcriptional and posttranscriptional effects, transcripts of genes including groEL, fld, kat, gor, gst, dps, bfr, tf, sodA, dnaK, prx, uspA, pcs and apx were quantified and found to be increased 1.33- to 7.70-fold in unstressed and 1.76- to 13.80-fold in stressed An + ahpC. In a converse manner, they were downregulated by 1.20- to 7.50-fold in unstressed and 1.23 to 10.20-fold in stressed AnΔahpC. It is concluded that the level of AhpC controls a major set of metabolic and developmental genes in normal and stress conditions and thus likely is in the core of the redox regulatory system of Anabaena. © 2016 Elsevier B.V.
Role of initial cell density of algal bioassay of toxic chemicals
(Wiley-VCH Verlag, 2016) Prashant Kumar Singh; Alok Kumar Shrivastava
A variety of toxicants such as, metal ions, pesticides, dyes, etc. are continuously being introduced anthropogenically in the environment and adversely affect to the biotic component of the ecosystem. Therefore, the assessment of negative effects of these toxicants is required. However, toxicity assessment anticipated by chemical analysis are extremely poor, therefore the application of the living systems for the same is an excellent approach. Concentration of toxicant as well as cell density both influenced the result of the algal toxicity assay. Here, Scenedesmus sp, a very fast growing green microalgae was selected for study the effects of initial cell densities on the toxicity of Cu(II), Cd(II), Zn(II), paraquat and 2,4-D. Results demonstrated concentration dependent decrease in biomass and specific growth rate of Scenedesmus sp. on exposure of abovesaid toxicants. Paraquat and 2,4-D emerged as extremely toxic to the test alga which reflected from the lowest EC value and very steep decline in biomass was evident with increasing concentration of paraquat and 2,4-D in the medium. Result also demonstrated that initial cell density is a very important parameter than specific growth rate for algal bioassay of various toxicants. Present study clearly illustrated that the use of smaller cell density is always recommended for assaying toxicity of chemicals in algal assays. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Salt and UV-B induced changes in Anabaena PCC 7120: Physiological, proteomic and bioinformatic perspectives
(2013) Snigdha Rai; Shilpi Singh; Alok Kumar Shrivastava; L.C. Rai
This study examines response of Anabaena sp. PCC 7120 to salt and UV-B stress by combining physiological, biochemical, proteomics and bioinformatics approaches. Sixty five significantly altered protein spots corresponding to 51 protein genes identified using MALDI-TOF MS/MS were divided into nine functional categories. Based on relative abundance, these proteins were grouped into four major sets. Of these, 27 and 5 proteins were up- and downregulated, respectively, both under salt and UV-B while 8 and 11 proteins showed accumulation in salt and UV-B applied singly. Some responses common to salt and UV-B included (i) enhanced expression of FeSOD, alr3090 and accumulation of MDA indicating oxidative stress, (ii) accumulation of PDH, G6P isomerase, FBPaldolase, TK, GAPDH and PGK suggesting enhanced glycolysis, (iii) upregulation of 6-PGD, 6PGL and NADPH levels signifying operation of pentose phosphate pathway, (iv) upregulation of Dps, NDK and alr3199 indicating DNA damage, and (v) accumulation of proteins of ribosome assembly, transcriptional and translational processing. In contrast, enhanced expression of RUBISCO, increased glycolate oxidase activity and ammonium content under salt signify the difference. Salt was found to be more damaging than UV-B probably due to a cumulative effect of ionic, osmotic and oxidative damage. A group of proteins having common expression represent decreased toxicity of salt and UV-B when applied in combination. © 2013 Springer Science+Business Media Dordrecht.
Secondary metabolites from algae: Benefits and future perspectives
(Nova Science Publisher Inc., 2018) Snigdha Rai; Alok Kumar Shrivastava; Shashikant Ray
Algae have gained worldwide attention fairly in the last decade owing to its role in the production of valuable chemicals and production of secondary metabolites with extensive biological activity. The chemical derived drugs and cosmetics have massive side effects due to this reason people attracted more towards herbal products. Most of the algae are easy to grow in minimal resources in fallow land areas with high productivity from secondary metabolites and medicinal point of view. Worldwide different research groups working on algae with a different motto. Production of oil from algae is considered to be one of the challenging tasks for the researcher. Whereas production of essential proteins, fatty acids, minerals, nutraceuticals, cosmetics, medicine and food industry from algae have already in progress with productive results. In this chapter, we have thoroughly discussed different secondary metabolites which are obtained from algae, how these products are beneficial for our society and what is their impact on coming future. © 2018 Nova Science Publishers, Inc.
Understanding the mechanisms of abiotic stress management in cyanobacteria with special reference to proteomics
(CRC Press, 2013) Snigdha Rai; Sarita Pandey; Alok Kumar Shrivastava; Prashant Kumar Singh; Chhavi Agrawal; Lal Chand Rai
Cyanobacteria are thought to have evolved around 3.5 billion years ago and have played a key role in earth’s transition from an anaerobic state to the aerobic one. They are the largest group of Gram-negative photosynthetic prokaryotes that has a close resemblance to higher plants in terms of lipid composition and protein assembly of the thylakoid membrane [1]. Cyanobacteria are ubiquitous in aquatic and terrestrial ecosystems including extreme habitats like hot springs, deserts, and polar regions. They occupy a central position in the nutrient cycling due to their unique capacity to fix atmospheric nitrogen into the assimilatory form (NH4+), thus contributing to the global nitrogen budget [2,3]. They are reported to play a key role in the maintenance of soil fertility [4] and have proved to be a potential biofertilizer in the form of plant-cyanobacterial symbiosis. Besides, many cyanobacterial species are reported to synthesize bioactive metabolites of potential therapeutic use [5]. It can therefore be concluded that cyanobacteria are a powerful model system for studying the molecular mechanisms of the responses and the acclimation strategies to abiotic stresses [6-8]. These mechanisms may provide models that may be applicable to plants as well. © 2013 by Taylor & Francis Group, LLC.
UV-B stress induced metabolic rearrangements explored with comparative proteomics in three Anabaena species
(Elsevier, 2015) Alok Kumar Shrivastava; Antra Chatterjee; Shivam Yadav; Prashant Kumar Singh; Shilpi Singh; L.C. Rai
Comparative proteomics together with physiological variables revealed different responses among three species of diazotrophic cyanobacterium Anabaena exposed to UV-B stress at the same time points. Perceptible decline in PSII activity, ATP pool, nitrogenase activity and respiration rate was observed for all the three species; this being maximum in Anabaena doliolum, followed by Anabaena sp. PCC 7120 and minimum in Anabaena L31. Statistical analysis of the protein abundance divided majority of them as early accumulated in A. L31, late accumulated in A. sp. PCC 7120 and downregulated in A. doliolum. Tolerance of A. L31 may be ascribed to post-translational modification reflected through the highest number of protein isoforms in its proteome followed by A. PCC 7120 and A. doliolum. Furthermore, increase in abundance of cyanophycinase, glutamine synthetase and succinate semialdehyde dehydrogenase in A. L31 suggests operation of an alternate pathway for assimilation of nitrogen and carbon under UV-B stress. An early accumulation of four proteins viz., glutamate ammonia ligase (Alr2328), transketolase (Alr3344), inorganic pyrophosphatase (All3570), and trigger protein (Alr3681) involved respectively in amino acid metabolism, energy metabolism, biosynthesis of cofactor and trigger protein and chaperone like activity across three species, suggests them to be marker of UV-B stress in Anabaena spp. This article is part of a Special Issue entitled: Proteomics in India. © 2015 Elsevier B.V.