Showing papers by "University of Seville published in 1981"
TL;DR: The binding of vasoactive intestinal peptide and the stimulation of adenylate cyclase were studied in mononuclear cells from human peripheral blood and VIP was a potent and efficient stimulator of cyclic AMP production.
151 citations
01 Jan 1981
TL;DR: The most fundamental biological process by which inorganic oxidized nitrogen is reduced to ammonia with water as the ultimate reductant at the expense of sun energy is Nitrate reduction by algae and higher plants.
Abstract: Nitrate reduction by algae and higher plants is one of the most fundamental biological processes by which inorganic oxidized nitrogen is reduced to ammonia with water as the ultimate reductant at the expense of sun energy (Losada and Guerrero, 1979). With the exception of some blue–green algae, and plants that have a symbiotic association with nitrogen-fixing prokaryotes, photosynthetic organisms derive most of their nitrogen from nitrate. There are besides a variety of nonphotosynthetic organisms, bacteria and fungi, that can also assimilate nitrate, as well as certain free-living anaerobic and aerobic bacteria that can fix molecular nitrogen.
56 citations
53 citations
TL;DR: It is concluded that transfer of intermediate substrates between the enzyme aggregates involved in carotenogenesis does occur in the wild type but not in heterokaryons for car A mutations, and is facilitated by Tween-80.
Abstract: Lycopene cyclization to gamma-carotene and then to beta-carotene is partially blocked in Phycomyces by the presence of car R mutations in heterokaryosis or by the addition of 2-(4-chlorophenyl)thiotriethylamine . HCl to the medium. We have quantitatively determined the carotenes synthesized by Phycomyces under conditions of partially blocked cyclization and in the presence of either car A mutations in heterokaryosis or polyoxyethylenesorbitan monooleate (Tween-80) in the medium. We conclude that transfer of intermediate substrates between the enzyme aggregates involved in carotenogenesis does occur in the wild type but not in heterokaryons for car A mutations, and is facilitated by Tween-80.
44 citations
TL;DR: In this paper, an approach is described for estimating yields of wheat, field corn (maize) and cotton on the basis of selected properties of soils when used under a high level of management.
40 citations
TL;DR: Ferredoxin-nitrite reductase (EC 1.7.1.) from the cyanobacteria Anabaena sp.
Abstract: Ferredoxin-nitrite reductase (EC 1.7.7.1.) from the cyanobacteria Anabaena sp. 7119 has been purified 763-fold with a specific activity of 21.5 units/nig protein (0.358 μkatals/mg). The enzyme has a molecular mass of 52,000 daltons with a Stokes radius of 3.09 nm and a sedimentation coefficient of 4.07 S. The cellular level of nitrite reductase activity gradually increases in response to the addition of increasing amounts of iron to the culture medium.
When partially purified nitrite reductase preparations are subjected to sucrose-density-gradient centrifugation there is a dose correspondence between nitrite reductase activity and absorbance at 400 nm. This suggests the association of a heme chromophore with the enzyme. Furthermore, the presence of an iron-sulfur center is suggested by a close association of acid-labile sulfide with nitrite reductase activity. Carbon monoxide inhibits nitrite reductase activity. The nature and kinetics of this reaction are comparable to other siroheme-containing nitrite reductases.
30 citations
TL;DR: In this article, the synthesis, characteristics, properties, and reactions with metallic ions of five aromatic derivatives of rhodanine have been studied, and suggestions have been made about the group responsibile for the reactionability.
30 citations
TL;DR: In this paper, a projection operator for computing nonequilibrium ensemble averages for systems that are close to a state of local equilibrium is developed, which is a straight-forward generalization of the Mori-Zwanzig techniques used in linear response theory.
Abstract: A simple projection operator method is developed for computing nonequilibrium ensemble averages for systems that are close to a state of local equilibrium. The formalism used here is a straight-forward generalization of the Mori-Zwanzig techniques used in linear response theory and it avoids many of the technical difficulties associated with time-dependent projection operators. The method is used here to derive gradient expansions for nonequibrium average values about their values in local equilibrium. This is used to derive the nonlinear hydrodynamic equations for a pure fluid, to Burnett order.
30 citations
TL;DR: The fifth case of lymphoma of the penis represents secondary involvement of nodal lymphoma and this neoplasm should be considered in the differential diagnosis of penile neoplasms.
27 citations
01 Jan 1981
TL;DR: The Donana Biological Reserve is located between 36°55′ and 37°3′ N latitude and 6°16′, 6°34′ W longitude on the western side of the Guadalqivir River in southwestern Spain this article.
Abstract: The Donana Biological Reserve is located between 36°55′ and 37°3′ N latitude and 6°16′ and 6°34′ W longitude on the western side of the Guadalqivir River in southwestern Spain.
25 citations
TL;DR: The effects of light on mycelial development are mediated by gene products involved in the behavioural responses of the macrophores, and another effect of light, the drastic growth inhibition of Phycomyces in 0.18 mM quinacrine, is seemingly independent of the mad sensory pathway.
Abstract: Blue light stimulates the formation of giant sporangiophores (macrophores) and inhibits the formation of dwarf sporangiophores (microphores) in Phycomyces grown under certain conditions The thresholds for these responses are lower than the threshold for phototropism of the macrophores Mutants in genes madA and madB, originally isolated because of the defective phototropism of their macrophores, are also defective in photomacrophorogenesis and photomicrophorogenesis These effects of light on mycelial development are thus mediated by gene products involved in the behavioural responses of the macrophoresAnother effect of light, the drastic growth inhibition of Phycomyces in 018 mM quinacrine, is seemingly independent of the mad sensory pathway
TL;DR: Inactive nitrate reductase, previously dialyzed to remove the inactivating agents, can be immediately reactivated by treatment with ferricyanide in a process requiring the removal of only one electron, independent of the system used to inactivate the enzyme.
TL;DR: In this paper, it was shown that cyclical structural changes are related to the formation of a high-surface-area phase of aragonite with a small content of microstrains and of a highly deformed calcite phase with a low surface area.
TL;DR: It is suggested that reduced nitrate reductase might bind acetylene at the nitrate active site, where molybdenum is supposed to be implicated, thus impairing the reduction of nitrate.
TL;DR: Rhodopseudomonas capsulata E1F1 bacteria photo-assimilated nitrate under anaerobic conditions, but were incapable of reducing it in the dark, according to X-ray diffraction analysis.
Abstract: Abstract Rhodopseudomonas capsulata E1F1 bacteria photo-assimilated nitrate under anaerobic conditions, but were incapable of reducing it in the dark. The bacteria utilized dissolved N2 as nitrogen source, but the growth in the presence of nitrate was 5-fold higher. Nitrite was excreted to the medium, but not stoichiometrically with respect to nitrate consumption. Nitrate reductase is particulate and used reduced viologens or flavins as electron donors for nitrate reduction. The enzyme was inhibited in vitro by KCN, NaN3, dithioerythritol and mercurials. Ammonia and other sources of reduced nitrogen repressed nitrate reductase synthesis.
TL;DR: In vitro complementation of the soluble assimilatory NAD(P)H-nitrate reductase was attained by mixing cell-free preparations of Chlamydomonas reinhardii mutant 104 and mutant 305, and was found to be similar to the wild enzyme in sucrose density sedimentation, molecular size, pH optimum, kinetic parameters, substrate affinity and sensitivity to inhibitors and temperature.
TL;DR: In Chlamydomonas a common cofactor is shared by xanthine dehydrogenase and nitrate reductase, which is repressed by ammonia and seems to be inessential for growth of Chlamyspora reinhardii.
Abstract: Wild-type Chlamydomonas reinhardii cells have xanthine dehydrogenase activity when grown with nitrate, nitrite, urea, or amino acid media Mutant strains 102, 104, and 307 of Chlamydomonas, lacking both xanthine dehydrogenase and nitrate reductase activities, were incapable of restoring the NADPH-nitrate reductase activity of the mutant nit-1 of Neurospora crassa, whereas wild type cells and mutants 203 and 305 had xanthine dehydrogenase and were able to reconstitute the nitrate reductase activity of nit-1 of Neurospora Therefore, it is concluded that in Chlamydomonas a common cofactor is shared by xanthine dehydrogenase and nitrate reductase Xanthine dehydrogenase is repressed by ammonia and seems to be inessential for growth of Chlamydomonas
TL;DR: In this article, the physical properties and fundamental solution chemistry of the complexes formed by PABH with Fe(II), Fe(III), Ni(II, Pd(II) and Ga(III) metal ions were investigated.
TL;DR: In this article, the selectivity of these oxides for the dehydrogenation-dehydration of the alcohols is discussed with reference to the fractional selectivity SF, where SF = 100 · rH2(rH2 + rH 2O).
TL;DR: In this article, the structural stability concept is used to study the sensitivity of complex systems to changes in parameters and tables, illustrated by applications to low-order urban dynamics models, and the way in which this concept permits a deeper study of the sensitivity in complex systems.
Abstract: This paper studies the value of the structural stability concept in relation to system dynamics models, illustrated by applications to low-order urban dynamics models. The way in which this concept permits a deeper study of the sensitivity of complex systems to changes in parameters and tables is shown. Forrester (1961), when establishing system dynamics, postulated the insensitivity of complex systems. The structural stability concept supplies a, theoretical framework for use in a deeper ' analysis of the sensitivity of a model. Structural stability is analysed by a study of the equilibrium surfaces in an appropriate space. These surfaces allow one to study the sensitivity of equilibrium points to parameter and table changes. Any change in the mode of behaviour of the model is shown by the existence of singularities in these surfaces, and this enables one to establish boundaries between regions of different models of behaviour and therefore a global perspective of the behaviour of the system is obtained....
TL;DR: Both nitrate and nitrite can physiologically act as primary Hill reagents in photosynthesis in blue-green algae and inhibit the quenching of fluorescence caused by nitrate or nitrite.
Abstract: The effect of nitrate and nitrite on long-term chlorophyll fluorescence has been studied in filamentous blue-green algae. Cells grown autotrophically with nitrate as nitrogen source show, under argon atmosphere, a high level of fluorescence. The addition of either nitrete or nitrite induces a significant fluorescence quenching, but, whereas in the case of nitrite no previous treatment is required, in the case of nitrate the cells have to be sonicated or treated with Triton X-100 in advance without destroying their cellular integrity. DCMU Abbreviations: BQ, p-benzoquinone; DCMU, 3-(3, 4-dichlorophenyl)-1, 1-dimethylurea; FCCP, carbonylcyanide 4-trifluoromethoxyphenylhydrazone; FeCy, potassium ferricyanide. strongly inhibits the quenching of fluorescence caused by nitrate or nitrite. Using cells grown with ammonia, a nutritional repressor of the two enzymes of the nitrate-reducing system, the fluorescence quenching observed in either case becomes negligible. These results clearly indicate that both nitrate and nitrite can physiologically act as primary Hill reagents in photosynthesis in blue-green algae.
TL;DR: The histogenesis of this axon whose initial outgrowth occurs on day 14 of incubation (HH-40), and the possible cause and mechanism of which are discussed.
Abstract: Among the types of horizontal cells of the avian retina, one has been described that has an axon terminating, in a typical structure. The present study analyses the histogenesis of this axon whose initial outgrowth occurs on day 14 of incubation (HH-40). The axon terminal is first detectable, towards day 15 of incubation (HH-41), in the form of a varicose thickening possessing short filopodia. The formation of the axon and the growth of the axon terminal is coincident with a retraction of the perikaryal process. The axon usually originates from one of the pricipal dendrites and in these stages shows short and fine filopodia throughout its length. From day 16 onwards (synaptic) spines may be distinguished, both in the dendritic field and on the axon terminal. The growth of the axon, in the phase when the axon terminal still has not formed, may exhibit deflections and deviations in its course, the possible cause and mechanism of which are discussed.
TL;DR: Clinical and histological investigations confirmed the fibro-histiocytic nature of the neoplasm and recurrences are common, and all have shown similar benign histological patterns.
Abstract: Fibro-histiocytic neoplasms are uncommon in the respiratory tract. This paper presents a clinical and histological description of a case of fibrous histiocytoma at the level of the third tracheal ring. This cases shares some features with the four cases previously described, viz., the growth occurs mainly in young adults; recurrences are common; and all have shown similar benign histological patterns. Ultrastructural investigations confirmed the fibro-histiocytic nature of the neoplasm.
TL;DR: It is proposed that these granules may produce the surface coat of stratum corneum and replacement cell layer and may function in the permeability of these cells.
TL;DR: A population of prepositus hypoglossi nucleus neurons with discharges correlated to gaze parameters and antidromically activated by stimulation of the ipsilateral oculomotor nucleus has been recorded in the alert cat.
TL;DR: The assimilatory nitrite reductase from the cyanobacterium Anabaena sp.
TL;DR: The analytical properties of the title compounds have been investigated and the 5,5'-dimethyl derivative is the most selective of the three.