Browsing by Author "J.B. Singh"

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Alkaline phosphatase tests: A useful aid for the identification of rhizobium trifolii strains
(1984) A.P. Singh; J.B. Singh
[No abstract available]
Atmospheric energy fluxes over tropical indian region during two contrasting monsoon years
(1996) J.B. Singh; U.S. Singh
Atmospheric energy fluxes over tropical Indian region have been computed from the surface to 300 mbar at intervals of 50 mbar for premonsoon and monsoon months during two contrast monsoon years of 1977 and 1979. The mean and eddy components due to meridional circulation have been separated. Poleward transport of these parameters over some of tropical Indian stations reveals several contrasting features. It has been found that some of these parameters can give very useful indications of ensuing monsoon performance over India.
Differential Synthesis of Alkaline Phosphatase in Rhizobium Species Isolated from the Tropics
(1984) Akhand P. Singh; J.B. Singh
A total of 28 strains of several species of Rhizobium were screened for the presence and regulation of the enzyme alkaline phosphatase. In contrast to all other species of Rhizobium the activity of this enzyme was absent in R. trifolii. Different levels of alkaline phosphatase were observed in various species of Rhizobium. Both, species as well as strain specific differences were found in the level of alkaline phosphatase. © 1984, Walter de Gruyter. All rights reserved.
Effects of low temperature on two cyanobacteria
(1992) D. Kumar; J.B. Singh; H.D. Kumar
[No abstract available]
Inhibition of photosynthetic electron transport in nostoc muscorum by ni2+and Ag+
(1991) J.B. Singh; S.M. Prasad; L.C. Rai
This paper presents the inhibition of photosynthetic electron transport chain of Nostoc muscorum by divalent Ni2+ and monovalent Ag 4. PS I (DCPIP/ASC͢MV) and PS II (H2O͢PBQ) activities were markedly inhibited by Ni21 and Ag+ in a concentration-dependent fashion but PS II was more susceptible than PS I to Ni2+. Ag+ was more toxic to PS I than PS II. The greater sensitivity of PS II to Ni2+ was further confirmed by the inhibition of DCPIP photoreduction and Chl a fluorescence. Restoration of Ag+-induced inhibition of DCPIP photoreduction and Chl a fluorescence by artificial electron donors (DPC, NH2OH, MnCl2) and their failure to restore Ni2+-induced inhibition suggests that Ni2+ inactivates PS II by causing alteration and destruction of photosynthetic membranes, but Ag+ inhibits the electron flow at the oxidizing side of PS II. Nevertheless, the suppression of the fluorescence intensity at low concentrations of both metal cations points to the involvement of phycobilisomes in the inhibition of PS II activity. © 1991, Applied Microbiology, Molecular and Cellular Biosciences Research Foundation. All rights reserved.
Invited review: Physics potential of the ICAL detector at the India-based Neutrino Observatory (INO)
(Indian Academy of Sciences, 2017) A. Kumar; A.M. Vinod Kumar; Abhik Jash; Ajit K Mohanty; Aleena Chacko; Ali Ajmi; Ambar Ghosal; Amina Khatun; Amitava Raychaudhuri; Amol Dighe; Animesh Chatterjee; Ankit Gaur; Anushree Ghosh; Ashok Kumar; Asmita Redij; B. Satyanarayana; B.S. Acharya; Brajesh C Choudhary; C. Ranganathaiah; C.D. Ravikumar; Chandan Gupta; D. Indumathi; Daljeet Kaur; Debasish Majumdar; Deepak Samuel; Deepak Tiwari; G. Rajasekaran; Gautam Gangopadhyay; Gobinda Majumder; H.B. Ravikumar; J.B. Singh; J.S. Shahi; James Libby; Jyotsna Singh; K. Raveendrababu; K.K. Meghna; K.R. Rebin; Kamalesh Kar; Kolahal Bhattacharya; Lalit M Pant; M Sajjad Athar; M.V.N. Murthy; Manzoor A Malik; M.D. Naimuddin; Mohammad Salim; Monojit Ghosh; Moon Moon Devi; Naba K Mondal; Nayana Majumdar; Nita Sinha; Nitali Dash; Pomita Ghoshal; Poonam Mehta; Prafulla Behera; R. Kanishka; Raj Gandhi; Rajesh Ganai; Rashid Hasan; S. Krishnaveni; S.M. Lakshmi; S.K. Singh; S.S.R. Inbanathan; S. Uma Sankar; Sadiq Jafer; Saikat Biswas; Sanjeev Kumar; Sanjib Kumar Agarwalla; Sandhya Choubey; Satyajit Saha; Shakeel Ahmed; Shiba Prasad Behera; Srubabati Goswami; Subhasis Chattopadhyay; Sudeb Bhattacharya; Sudeshna Banerjee; Sudeshna Dasgupta; Sumanta Pal; Supratik Mukhopadhyay; Sushant Raut; Suvendu Bose; Swapna Mahapatra; Tapasi Ghosh; Tarak Thakore; V.K.S. Kashyap; V.S. Subrahmanyam; Venktesh Singh; Vinay B Chandratre; Vipin Bhatnagar; Vivek M Datar; Waseem Bari; Y.P. Viyogi
The upcoming 50 kt magnetized iron calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) is designed to study the atmospheric neutrinos and antineutrinos separately over a wide range of energies and path lengths. The primary focus of this experiment is to explore the Earth matter effects by observing the energy and zenith angle dependence of the atmospheric neutrinos in the multi-GeV range. This study will be crucial to address some of the outstanding issues in neutrino oscillation physics, including the fundamental issue of neutrino mass hierarchy. In this document, we present the physics potential of the detector as obtained from realistic detector simulations. We describe the simulation framework, the neutrino interactions in the detector, and the expected response of the detector to particles traversing it. The ICAL detector can determine the energy and direction of the muons to a high precision, and in addition, its sensitivity to multi-GeV hadrons increases its physics reach substantially. Its charge identification capability, and hence its ability to distinguish neutrinos from antineutrinos, makes it an efficient detector for determining the neutrino mass hierarchy. In this report, we outline the analyses carried out for the determination of neutrino mass hierarchy and precision measurements of atmospheric neutrino mixing parameters at ICAL, and give the expected physics reach of the detector with 10 years of runtime. We also explore the potential of ICAL for probing new physics scenarios like CPT violation and the presence of magnetic monopoles. © Indian Academy of Sciences.
Metal-induced inhibition of photosynthetic electron transport chain of the cyanobacterium Nostoc muscorum
(1991) S.M. Prasad; J.B. Singh; L.C. Rai; H.D. Kumar
This study presents information on the mechanism of inhibition of the photosynthetic electron transport of Nostoc muscorum by chromium (Cr) and lead (Pb). Photosystem II (PS II) was found to be more sensitive both to low and high concentrations of test metals used. A considerable inhibition of photosystem I (PS I) was, however, observed at high concentrations only. Although Cr-induced inhibition of DCPIP photoreduction and lowering of chlorophyll a (Chl a) fluorescence intensity (F685) could not be reversed by artificial electron donors (diphenyl-carbazide (DPC), NH2OH, MnCl2 and benzidine) of PS II, these electron donors did substantially reverse the Pb-induced inhibition of DCPIP photoreduction as well as the lowering of Chl a fluorescence. Nevertheless, an increase in Chl a fluorescence at high concentrations of Pb suggested that this metal also arrests electron flow on the reducing side of the PS II reaction centre. Besides this, the suppression of fluorescence intensity of phycocyanin at low concentrations of both metals points to the involvement of phycobilisomes in the inhibition of PS II activity. The present study demonstrates that the modes of action of Cr and Pb on PS II are quite different. © 1991.
Physiologic effect of 50-Hz emf-induced nutrient solution on a cyanobacterium, Nostoc muscorum
(1999) Subas Rai; Tarun K. Garg; J.B. Singh; D. Kumar; B.N. Singh
A solution-mediated effect of extremely low-frequency (ELF) powerline (50-Hz) field was studied on the physiology of a cyanobacterium, Nostoc muscorum. Samples were exposed to 35- and 51.2- μT uniform fields for different lengths of time. The electromagnetic field produced significantly different effects, varying with the length of exposure and field strength. The effects were attributed to differential changes in the structural chemistry of the solution. Treated solutions were suggested to have caused the effects by selective sorting of ions and bringing about conformational changes in biomolecules and the systems.
Physiologic Effect of 50-Hz EMF-Induced Nutrient Solution on a Cyanobacterium, Nostoc muscorum
(Marcel Dekker Inc., 1999) Subas Rai; Tarun K. Garg; J.B. Singh; D. Kumar; B.N. Singh
A solution-mediated effect of extremely low-frequency (ELF) powerline (50-Hz) field was studied on the physiology of a cyanobacterium, Nostoc muscorum. Samples were exposed to 35- and 51.2-μT uniform fields for different lengths of time. The electromagnetic field produced significantly different effects, varying with the length of exposure and field strength. The effects were attributed to differential changes in the structural chemistry of the solution. Treated solutions were suggested to have caused the effects by selective sorting of ions and bringing about conformational changes in biomolecules and the systems.
Physiological and Biochemical Characteristics of a Copper Tolerant and a Wild Type Strain of Anabaena doliolum Under Copper Stress
(1991) L.C. Rai; Nirupama Mallick; J.B. Singh; H.D. Kumar
Copper tolerance in Anabaena doliolum has been studied by comparing the physiological properties of its wild type and Cu-tolerant strains. A concentration dependent reduction in growth, pigments, protein, sugar, lipid and ATP content, photosynthetic electron transport chain, O2-evolution, carbon fixation, nutrient uptake (NH+4 and NO--3), nitrate reductase, nitrogenase, glutamine synthetase and alkaline phosphatase activities was noticed in both the strains following Cu-supplementation. The reduction in all parameters was higher in wild type than the tolerant strain. The latter produced a larger (19.5 %) lipid fraction than the wild type even in the absence of added metal. As compared to the wild strain, the tolerant strain showed enhanced enzyme activities, especially of alkaline phosphatase (20 % higher), low copper uptake and insignificant loss of K+ and Na+. The data on lipid production, loss of K+ and Na+, and uptake of copper collectively indicate a change in the permeability of the plasma membrane and a possible operation of «exclusion mechanism» in the tolerant strain thereby reducing the toxic effect of copper even at a high concentration. © 1991, Gustav Fischer Verlag, Stuttgart. All rights reserved.
Potassium salts inhibit growth of the cyanobacteria Microcystis spp. in pond water and defined media: Implications for control of microcystin- producing aquatic blooms
(American Society for Microbiology, 1997) D.L. Parker; H.D. Kumar; L.C. Rai; J.B. Singh
Ten metals were assayed in 21 Indian ponds which comprised three groups: (i) eutrophic alkaline ponds containing <2.5 mM potassium and thick growths of Microcystis aeruginosa or Microcystis flos-aquae during most of the year, (ii) equally eutrophic alkaline ponds containing >2.8 mM potassium and no detectable Microcystis growth, and (iii) oligo- or mesotrophic ponds with various potassium and hydrogen ion concentrations and no persistent Microcystis blooms. The effects of potassium on Microcystis growth were examined in filter-sterilized pond water and in defined culture media. A 50% reduction in the 10-day yield of cultured M. aeruginosa was observed in DP medium and pond water supplemented with 1 and 3 mM KCl, respectively. In contrast, the addition of 2 to 30 mM NaCl did nut suppress the growth of M. aeruginosa in either DP medium or pond water. Both 5 mM KCl and 20 mM KHCO3 in J medium strongly inhibited the growth of M. flos-aquae C3-9, whereas 5 to 30 mM NaCl had no effect and 20 mM NaHCO3 was stimulatory. For pond water cultured with a mixture of M. aeruginosa and the duckweed Wolffia arrhiza, M. aeruginosa dominated in unsupplemented water and W. arrhiza dominated in water supplemented with 4.8 mM KCl. Implications for the ecology and control of Microcystis blooms are discussed.
Regulation of ß-galactosidase synthesis in wild type and in a succinate-resistan mutant of rhizobium meliloti
(1985) A.P. Singh; J.B. Singh
The synthesis of β-galactosidase in Rhizobium meliloti WU60 was found to be inducible by lactose and its non-m etabolizable analogue, isopropyl-β-D-thiogalactoside (IPTG). In contrast to Escherichiacoli, galactose and melibiose werevery weak inducers of this enzyme in R. meliloti. The maximum level of β-galactosidase in this bacterium is 2% of that in fully induced E. coli. In addition to glucose, the induced synthesis of this enzyme in R. meliloti was repressed by galactose, glycerol, and succinate. In comparison to E. coli, addition of cyclic AMP to the growth medium of R. meliloti did not alleviate the repressive effect of the above compounds on β-galactosidase synthesis. High concentrations of sodium succinate (100 mM) were inhibitory to the growth of R. meliloti. Spontaneous succinate-resistant mutants could be isolated at low frequency. In contrast to wild type parent, in a succinate-resistant mutant, the synthesis of β-galactosidase was not repressed by succinate High concentrations of sodium succinate (100 mM) were inhibitory to the growth of R. meliloti. Spontaneous succinate-resistant mutants could be isolated at low frequency. In contrast to thewild type parent, in a succinate-resistant mutant, the synthesis of β-galactosidase was not repressed by succinate. © 1985, Walter de Gruyter. All rights reserved.