Showing papers by "Jawaharlal Nehru University published in 1992"
TL;DR: It seems likely thatlipids are required for sustaining the photosynthetic activity under environmental stress, and a loss in activity is observed as the lipids are degraded either by high light or high temperature stress.
Abstract: Effects of high light and temperature stress on the structure and function of the photosynthetic apparatus of wheat (Triticum aestivum) were studied. There was a decrease in the electron transport activity of chloroplasts isolated from photoinhibited and heat-stressed leaves. Chlorophyll fluorescence was measured in photoinhibited and heat-stressed leaves and the decrease in variable fluorescence and variable to maximum fluorescence ratio of the stressed leaves indicated a loss in the quantum yield of photosynthesis. The decrease in electron transport activity was accompanied by an increase in peroxidation of thylakoid lipids. Lipid peroxidation indicated the oxidative degradation of polyunsaturated fatty acyl residues of the thylakoid lipids. A negative correlation was observed between electron transport activity and lipid peroxidation. The electron transport activity was completely lost as the peroxidation level reached a threshold equivalent to 0.6 micromoles malondialdehyde. The threshold of lipid peroxidation for complete loss of activity was the same for both photoinhibition and heat treatment, suggesting that the nature of the environmental stress may be less important with respect to the relationship between electron transport and lipid peroxidation. Thus, it seems likely that lipids are required for sustaining the photosynthetic activity under environmental stress, and a loss in activity is observed as the lipids are degraded either by high light or high temperature stress.
162 citations
TL;DR: Protochlorophyllide was the most abundant pigment accumulated in intact chloroplasts isolated from 5-aminolevulinic acid-treated plants and was probably acting as type II photosensitizer.
Abstract: Cucumber (Cucumis sativus L., cv Poinsette) plants were sprayed with 20 millimolar 5-aminolevulinic acid and then incubated in the dark for 14 hours. The intact chloroplasts were isolated from the above plants in the dark and were exposed to weak light (250 micromoles per square meter per second). Within 30 minutes, photosystem II activity was reduced by 50%. The singlet oxygen (1O2) scavengers, histidine and sodium azide (NaN3) significantly protected against the damage caused to photosystem II. The hydroxyl radical scavenger formate failed to protect the thylakoid membranes. The production of 1O2 monitored as N,N-dimethyl p-nitrosoaniline bleaching increased as a function of light exposure time of treated chloroplasts and was abolished by the 1O2 quencher, NaN3. Membrane lipid peroxidation monitored as malondialdehyde production was also significantly reduced when chloroplasts were illuminated in the presence of NaN3 and histidine. Protochlorophyllide was the most abundant pigment accumulated in intact chloroplasts isolated from 5-aminolevulinic acid-treated plants and was probably acting as type II photosensitizer.
123 citations
TL;DR: In this paper, the ozone levels varied from 9.4 to 128.31 ppbv exhibiting wide temporal and seasonal variation, and the ozone concentration invariably peaked at noontime and remained high during early summer and spring periods.
82 citations
TL;DR: The results suggest that norepinephrine induced preoptic area mediated influence on the body temperature is primarily regulated by the alpha 1 receptors while the sleep and wakefulness are regulated by alpha 2 and beta receptors, respectively.
81 citations
Journal Article•
TL;DR: Diosgenin showed a lack of progesterogenic action as was apparent from the absence of alveolar development even in the presence of exogenous estrogen, and augmentation of estrogenic effect of diosgenin especially at the higher dose level.
Abstract: Estrogenic action of diosgenin on the mammary epithelium of ovariectomized (OVX) mouse has been reported. Diosgenin when administered (sc) at the dose levels of 20 and 40 mg/kg body weight for a period of 15 days stimulated the growth of mammary epithelium. This was indicated by the increase in DNA content, increase in number of ducts and appearance of terminal endbuds. There was a significant increase in the mammary development scores in the presence of diosgenin. Concomitant treatment of estrogen and diosgenin showed augmentation of estrogenic effect of diosgenin especially at the higher dose level (40 mg/kg body wt). Diosgenin showed a lack of progesterogenic action as was apparent from the absence of alveolar development even in the presence of exogenous estrogen.
81 citations
TL;DR: Analysis of RNA and protein in developing seeds showed that AmA1 is synthesized during early embryogenesis, reaching a maximum by midmaturation, as no RNA was detected in 1-day-old seedlings although the protein showed delayed breakdown on germination.
Abstract: An albumin with a well-balanced amino acid composition and high levels of the essential amino acids was purified to homogeneity from the mature seeds of Amaranthus hypochondriacus. The amino acid composition of this protein is comparable to the World Health Organization recommended values for a highly nutritional protein. The protein is a 35-kDa monomer with four isoforms that can be separated by chromatofocusing. Antibodies raised against one of the isoforms, AmA1, cross-reacted with the other three isoforms. Affinity-purified AmA1 antibodies were used to isolate cDNA clones from a developing-seed expression library. The six immunopositive recombinants obtained were found to be related. The cDNA of the largest clone (1.2 kilobases) has a single major open reading frame corresponding to a 304-amino acid polypeptide. The clone was confirmed by hybrid-selected translation and immunoprecipitation. The size of the immunoprecipitated product was identical to the mature protein. Analysis of RNA and protein in developing seeds showed that AmA1 is synthesized during early embryogenesis, reaching a maximum by midmaturation. No RNA was detected in 1-day-old seedlings although the protein showed delayed breakdown on germination. Expression of the AmA1 gene was found to be seed-specific, as no protein or RNA was detected in other plant tissues.
77 citations
TL;DR: The fluctuation in phospholipid composition have led to altered properties of plasma membrane namely, membrane fluidity, transport activities and drug sensitivity, which suggest that-a critical level of individual phospholIPid is important for proper functioning of the plasma membrane.
55 citations
01 Apr 1992
TL;DR: This paper presents a Hierarchical Censored Production Rules system as an underlying representational and computational scheme for variable precision logic and shows that it can be employed to exhibit both variable specificity and certainty of belief in a conclusion using a General Control Scheme (GCS).
Abstract: Variable precision logic offers mechanisms for handling trade-offs between the precision of inferences and the computational efficiency of deriving them. In this paper we present a Hierarchical Censored Production Rules (HCPRs) system as an underlying representational and computational scheme for variable precision logic. The proposed scheme is based on an extension of Production Rules system. It is shown how an ordinary Production Rule on suitable modification and augmentation with relevant information becomes a Hierarchical Censored Production Rule (HCPR), which in turn enables to resolve many of the problems associated with usual Production Rules system. A concept of Hierarchical Censored Production Rule tree (HCPR-tree) is developed and it is shown that it can be employed to exhibit both variable specificity and certainty of belief in a conclusion using a General Control Scheme (GCS).
54 citations
TL;DR: It was observed that Pb and Cd hair levels of males working in rural areas were lower than in male businessmen and officers working in an urban area of New Delhi, thereby showing the different levels of element exposure of the rural subjects.
Abstract: Samples of hair and nails collected from the residents of Wazirpur, a village adjacent to New Delhi, were analyzed for Cd, Cr, Cu, Mn, Ni, Pb, and Zn, and correlated with the residents' rural and urban places of occupations. It was observed that Pb and Cd hair levels of males working in rural areas were lower than in male businessmen and officers working in an urban area of New Delhi, thereby showing the different levels of element exposure of the rural subjects. Such differences in the hair levels of elements were not observed among female subjects. The tobacco smoking habits of male and female rural subjects using hookah were associated with increased Cd levels in hair and nails.
50 citations
TL;DR: In this article, the particle-size distribution of the suspended sediments in the Cauvery River was examined and it was shown that the less than 20 μm fraction accounts for nearly 60% of the total sediment transported by the river.
43 citations
TL;DR: The results demonstrated significant increases in the activities of the metabolizing enzymes and levels of catecholamines during experimental conditions, and the levels ofCatecholamine were highest in the cerebral hemispheres, the region associated with high activities ofThe metabolizing enzyme.
Abstract: The levels of epinephrine, norepinephrine, and dopamine and the activities of tyrosine hydroxylase and monoamine oxidase were estimated in four regions of rat brain during alloxan-induced hyperglycemia and insulin-induced hypoglycemia. Catecholamine levels were estimated by HPLC, and the insulin levels were quantified by radioimmunoassay. The results demonstrated significant increases in the activities of the metabolizing enzymes and levels of catecholamines during experimental conditions. The levels of catecholamines were highest in the cerebral hemispheres, the region associated with high activities of the metabolizing enzymes. Insulin-induced hypoglycemia caused a decrease in the activities of the metabolizing enzymes followed by their recovery within 2 h.
TL;DR: The study clearly indicates that vanadate can effectively normalize many metabolic abnormalities even at a low insulin level in both insulin-dependent and -independent tissues of diabetic rats.
TL;DR: The above data support the existence of a major acidic glycoconjugate in E. histolytica bearing striking structural similarities to the lipophosphoglycan of Leishmania.
TL;DR: It is observed that there exists some positive correlation between element levels in hair and nails and CHD, hypertension, and diabetes of these subjects.
Abstract: The concentrations of Cd, Cr, Cu, Mn, Ni, Pb, and Zn were estimated in hair and nails of urban residents of New Delhi. Particularly, hair levels of Cu and Mn in hypertensive males, Cr and Zn in hypertensive females, and Zn in CHD and diabetic females, and nail levels of Zn in CHD and hypertensive females were significantly lower than controls. Thus, it is observed that there exists some positive correlation between element levels in hair and nails and CHD, hypertension, and diabetes of these subjects.
TL;DR: This spectrofluorometric method designed for the determination of protoporphyrin IX, esterified and nonesterified Mg-protoporphyr in pool, and protochlorophyllide is far superior to available spectrophotometric methods and estimates as low as 1 nM concentration of plant pigments.
TL;DR: This work presents results from numerical simulations using a ``cell-dynamical system'' to obtain solutions to the time-dependent Ginzburg-Landau equation for a scalar, two-dimensional (2D) model in the presence of a sinusoidal external magnetic field.
Abstract: We present results from numerical simulations using a ``cell-dynamical system'' to obtain solutions to the time-dependent Ginzburg-Landau equation for a scalar, two-dimensional (2D), (${\mathrm{\ensuremath{\Phi}}}^{2}$${)}^{2}$ model in the presence of a sinusoidal external magnetic field. Our results confirm a recent scaling law proposed by Rao, Krishnamurthy, and Pandit [Phys. Rev. B 42, 856 (1990)], and are also in excellent agreement with recent Monte Carlo simulations of hysteretic behavior of 2D Ising spins by Lo and Pelcovits [Phys. Rev. A 42, 7471 (1990)].
TL;DR: The data suggest that surface antigens of E. histolytica can be modulated in response to bacteria and may provide an explanation for the observed influence of bacteria on amebic virulence.
Abstract: Changes in the cell surface of Entamoeba histolytica, a human intestinal parasite and the causative agent of amebic dysentery, were examined with a monoclonal antibody, 2D7.10, which selectively recognizes carbohydrate epitopes in some axenic amebic strains. While high-level expression of this epitope was observed in axenic amebae, it was either absent or present only in small amounts in xenic amebae. Furthermore, reassociation of the axenic amebae with intestinal flora resulted in loss of the 2D7.10 epitope. Our data suggest that surface antigens of E. histolytica can be modulated in response to bacteria and may provide an explanation for the observed influence of bacteria on amebic virulence.
TL;DR: The acute pre-treatment with caffeine reduced the radiation-induced frequency of chromosomal aberrations discernibly, whereas the chronic pre- treatment afforded a much more significant degree of radioprotection.
Abstract: The effect of caffeine given as pre- and post-treatment in mice exposed to whole-body γ-irradiation (1.5 Gy 60 Co γ-rays) was studied. The pre-treatment was either acute or chronic. The acute dose (5 mg/kg and 15 mg/kg body weight) was in the form of an injection given intraperitoneally, 30 min before irradiation. The chronic administration was in the form of caffeine solution (4.208 × 10 −3 M and 7.72 × 10 −4 M) contained in the drinking water that mice had had ad libitum access to instead of plain drinking water for 5 weeks prior to radiation exposure. The acute pre-treatment with caffeine reduced the radiation-induced frequency of chromosomal aberrations discernibly, whereas the chronic pre-treatment afforded a much more significant degree of radioprotection. The caffeine post-treatment (5 mg/kg and 15 mg/kg body weight) was given in the form of an intraperitoneal injection to the mice immediately following whole-body γ-irradiation. It is noted that both post-treatment concentrations of caffeine also significantly reduced the frequency of chromosomal aberratios induced by γ-rays. These data are briefly discussed in terms of possible mechanistic considerations.
TL;DR: High levels of Mn and Cr were found in male healthy workers and unhealthy workers with chronic headaches and dizziness, and in the case of female workers, higher Mn and lower Pb levels were found, but the level of any element was not significantly different in the workers with ulcers and asthma.
TL;DR: The analysis of the dark-relaxation kinetics of variable fluorescence, Fv, in intact green leaves of Pisum stativum L. and Dolichos lablab L. indicates that a mechanism other than ATP-driven back-transfer of electrons to QA may be responsible for the phenomenon.
Abstract: The dark-relaxation kinetics of variable fluorescence, Fv, in intact green leaves of Pisum stativum L. and Dolichos lablab L. were analyzed using modulated fluorometers. Fast (t1/2 = 1 s) and slow (t1/2 = 7–8 s) phases in fv dark-decay kinetics were observed; the rate and the relative contribution of each phase in total relaxation depended upon the fluence rate of the actinic light and the point in the induction curve at which the actinic light was switched off. The rate of the slow phase was accelerated markedly by illumination with far-red light; the slow phase was abolished by methyl viologen. The halftime of the fast phase of Fv dark decay decreased from 250 ms in dark-adapted leaves to 12–15 ms upon adaptation to red light which is absorbed by PSII. The analysis of the effect of far-red light, which is absorbed mainly by PSI, on Fv dark decay indicates that the slow phase develops when a fraction of QA− (the primary stable electron acceptor of PSII) cannot transfer electrons to PSI because of limitation on the availability of P700+ (the primary electron donor of PSI). After prolonged illumination of dark-adapted leaves in red (PSII-absorbed) light, a transient. Fv rise appears which is prevented by far-red (PSI-absorbed) light. This transient fv rise reflects the accumulation of QA− in the dark. The observation of this transient Fv rise even in the presence of the uncoupler carbonylcyanide m-chlorophenyl hydrazone (CCCP) indicates that a mechanism other than ATP-driven back-transfer of electrons to QA may be responsible for the phenomenon. It is suggested that the fast phase in Fv dark-decay kinetics represents the reoxidation of QA− by the electron-transport chain to PSI, whereas the slow phase is likely to be related to the interaction of QA− with the donor side of PSII.
TL;DR: The data suggests that brain insulin receptor kinase is regulated differently compared to peripheral tissues and supports the concept of an active brain insulin receptors in vivo.
TL;DR: In this paper, the authors used Indian Remote Sensing Satellite-IA (IRS-1A) Linear Imaging Self Scanning-I (LISS-I) digital data in combination with field measurement for the estimation of suspended solids concentration in an inland water body (reservoir).
Abstract: The objective of this study was to use Indian Remote Sensing Satellite-IA (IRS-1A) Linear Imaging Self Scanning-I (LISS-I) digital data in combination with field measurement for the estimation of suspended solids concentration in an inland water body (reservoir). For this purpose, a small reservoir (Tawa), on the Tawa river of the Narmada basin in Central India, was studied. The Tawa reservoir water samples were collected on 28 September and 20 October 1988, concurrent with IRS-1A overpass. Reservoir water samples have been analysed to determine grain size analysis and mineralogy.
TL;DR: In this paper, the effect of varying concentrations of sodium chloride (NaCl) (0, 100, 150 and 200 mM) on seedling growth, pigment composition and the primary photochemical activities in cotyledonary leaves of Brassica juncea cv was investigated.
TL;DR: Ordered forms of a synthetic dodecamer, d-AGATCTAGatCT, a direct repeat of the BglII recognition sequence, have been investigated using UV, CD, and fluorescence spectroscopy to test the "bookmark" hypothesis and a groove-cum-intercalation mode of binding.
Abstract: Ordered forms of a synthetic dodecamer, d-AGATCTAGATCT, a direct repeat of the BglII recognition sequence, have been investigated using UV, CD, and fluorescence spectroscopy Complex hairpin-duplex equilibria are manifest in UV thermal transitions, which are monophasic in the presence of very low or high NaCl concentrations but distinctly biphasic at intermediate ionic strengths In 100 mM NaCl, the 1/Tm vs 1n C curve has a reasonable positive slope, which yields delta H and delta S for duplex formation as -662 kcal/mol and -190 cal/mol, respectively Interaction of the dodecamer in duplex form with a tryptophan-containing peptide, KGWGK, has also been investigated to test the "bookmark" hypothesis (Gabbay et al, 1976) under the uniform structural constraint of the oligonucleotide of defined sequence CD spectra of the peptide (P), the oligonucleotide (N), and their mixtures at different P/N ratios show a dramatic change in peptide spectrum but little change in nucleic acid dichroism with peptide binding The Tm of P-N complexes decreases with an increase in peptide binding and levels off at saturation binding of P/N = 20 The data are interpreted in terms of a groove-cum-intercalation mode of binding, where intercalation to the tryptophan side chain destabilizes the double helix A Scatchard plot of the binding data is nonlinear, with best-fit values for an overall association constant K = 433 x 10(5) M-1, and the number of binding sites n = 323 when fitted to the site-exclusion model of binding
TL;DR: It is found that at large time and length scales the self-organized critical behavior is lost for any finite concentration of defects both in the model of random holes and in those models of random critical heights in which the dynamic rule violates the height conservation law.
Abstract: We study numerically the scaling behavior of disordered sandpile automata with preferred direc tion on a two-dimensional square lattice. We consider two types of bulk defects that modify locally the dynamic rule: (i) a random distribution of holes, through which sand grains may leave the sys tem, and (ii) several models with a random distribution of critical heights. We find that at large time and length scales the self-organized critical behavior, proved exactly in the pure model, is lost for any finite concentration of defects both in the model of random holes and in those models of random critical heights in which the dynamic rule violates the height conservation law. In the case of the ran dom critical height model with the height-conserving dynamics, we find that self-organized criticality holds for the entire range of concentrations of defects, and it belongs to the same universality class as the pure model. In the case of random holes we analyze the scaling properties of the probability distributions P(T,p, L) and D(s,p, L) of avalanches of duration larger than T and size larger than s, respectively, at lattices with linear size L and concentration of defect sites p. We find that in general the following scaling forms apply: P(T) = T-ap(T/x,T/L) and D(s) = sT 1J(s/m,s/L"), where x == x(p) and m == m(p) are the characteristic duration (length) and the characteristic size (mass) of avalanches for a given concentration of defects. The power-law behavior of the distributions still persists for length scales T <: x(p) and mass scales s <: m(p). The characteristic length x(p) and mass m(p) are finite for small concentrations of defects and diverge at p -+ 0 according to the power law x(p) '" p-I-I" and m(p) '" p-I-'m, with the numerically determined values of the exponents close to /l-x = 1 and /l-m = 1.5. The finite-size of the lattice may affect the measured probability distributions if for a given concentration of defects the characteristic length x(p) exceeds the lattice size L. A finite-size scaling analysis for the mass distribution yields the exponent v = 1.5, while the duration of the avalanches scales linearly with the size. We also determine the exponent D = 1.5 that connects the mass and the duration of avalanches.
TL;DR: A PKC-type activity was found to be stimulated by PMA in partially purified fractions and this suggests the involvement of protein kinase C (PKC)-type enzyme in light-mediated stimulation of NR.
TL;DR: The interactions of three tryptophan-containing peptides, KWK, KGWK tert-butyl ester, and KGWGK, with two self-complementary dodecamers of the same base composition but different sequence were studied by UV, CD, and fluorescence spectroscopy to discuss two different modes of binding of oligopeptides to the DNA hairpins.
Abstract: The interactions of three tryptophan-containing peptides, KWK, KGWK tert-butyl ester, and KGWGK, with two self-complementary dodecamers of the same base composition but different sequence were studied by UV, CD, and fluorescence spectroscopy. The oligonucleotides, d-AGATCTAGATCT and d-AAGCTTAAGCTT, contain tandem repeats of the recognition site for the restriction enzyme BglII in the former and HindIII in the latter. Thermal transition data in dilute solutions and in 0.01 M NaCl indicate these dodecamers to be present in hairpin forms. Binding of peptides to these hairpins was followed by tryptophan fluorescence quenching titrations at 10 mM Na + ; the data suggest intercalation of the indole ring. The association constants for the peptide-oligonucleotide (PN) complexes are an order of magnitude higher (10 5 M) than those reported with polynucleotides [10 4 M; Rajeswari et al. (1987) Biochemistry 26, 6825]. The pentapeptide, KGWGK, discriminates between BglII and HindIII sequences with higher affinity for the HindIII dodecamer. The CD maximum of KGWGK, at 220 nm, is drastically diminished upon interaction with oligonucleotides. The ellipticity at 220 nm is halved at 10 times less P/N ratio with the HindIII dodecamer than the BglII dodecamer, suggesting stronger binding to the HindIII dodecamer. The results are discussed in terms of two different modes of binding of oligopeptides to the DNA hairpins.
TL;DR: In this article, the soft-X-ray absorption spectra at the oxygen K-edge of La1-xSrxCoO3-δ (x = 0.0, 0.1,0.2, and 0.4) series with experimentally determined δ values were reported.
Abstract: We report the soft-X-ray absorption spectra at the oxygen K-edge of La1-xSrxCoO3-δ (x = 0.0, 0.1, 0.2, 0.3 and 0.4) series with experimentally determined δ values. We show that the doping of holes by replacing La3+ with Sr2+ induces states within the band gap of the insulating undoped compound for small x and these doped states have a very substantial oxygen 2p character. This indicates that the insulating compounds belong to the charge transfer insulator regime. With increasing Sr content, the doped states broaden into a band overlapping the top of the primarily oxygen p-derived band, leading to an insulator-metal transition at x ≥ 0.2.
TL;DR: The ribosomal RNA genes of the protozoan parasite Entamoeba histolytica are highly repeated and display restriction fragment length polymorphism, and an analysis of the DNA bands generated by EcoRI digestion of Entamoe DNA is presented.