Showing papers by "University of Córdoba (Spain) published in 1994"
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01 Oct 1994TL;DR: In this paper, the authors present an analytical approach for the separation of supercritical fluids in the analytical process, based on a set of properties of the supercritical fluid, including: 1.1 Basic Features of the Supercritical Fluid.
Abstract: 1 Preliminary Operations of the Analytical Process.- 1.1 Analytical Chemistry Today.- 1.2 The Analytical Process.- 1.3 Preliminary Operations of the Analytical Process.- 1.3.1 Basic Features.- 1.3.2 Most Common Steps.- 1.3.3 Recent Developments.- 1.4 Analytical Separation Techniques.- 1.4.1 Objectives.- 1.4.2 Classifications.- 1.4.3 Continuous Separation Techniques.- 1.5 Extraction Systems in Analytical Chemistry.- 1.6 Analytical Leaching Methodologies.- 1.7 Ideal Features of an Analytical Leaching System.- 1.8 Supercritical Fluids and Analytical Chemistry.- References.- 2 Physico - Chemical Properties of Supercritical Fluids.- 2.1 Definition of Supercritical Fluid.- 2.2 Physical Properties of Supercritical Fluids.- 2.2.1 Properties at or near the Critical Point.- 2.2.2 Properties of the Supercritical Region.- 2.2.2.1 Density.- 2.2.22 Diffusivity.- 2.2.2.3 Viscosity.- 2.2.2.4 Dielectric Constant.- 2.3 Binary Systems.- 2.4 Polarity.- 2.4.1 The ?* Polarizability/Polarity Scale.- 2.5 Reactions in or with Supercritical Fluids.- 2.5.1 Reactions in Supercritical Fluids.- 2.5.1.1 Influence of Pressure on the Reaction Rate.- 2.5.1.2 Catalytic Effects.- 2.5.1.3 Supercritical Water as an Exceptional Reaction Medium.- 2.5.1.4 Enzymatic Reactions in Supercritical Fluids.- 2.5.2 Reactions with Supercritical Fluids.- 2.6 Other Properties of Supercritical Fluids.- 2.7 General Applications of Supercritical Fluids.- 2.7.1 Industrial Processes.- 2.7.1.1 Supercritical Fluids in the Food Industry.- 2.7.1.2 Polymer Processing with Supercritical Fluids.- 2.7.2 Processing of Heavy Hydrocarbons.- 2.7.3 Analytical Applications of Supercritical Fluids.- 2.7.4 Waste Detoxification with Supercritical Fluids.- 2.7.5 Other Applications of Supercritical Fluids.- References.- 3 Theoretical and Practical Aspects of Supercritical Fluid Extraction.- 3.1 Introduction.- 3.2 Foundation of Leaching.- 3.3 Purity of Supercritical Fluids.- 3.4 Solubility in Supercritical Fluids.- 3.4.1 Solubility Measurements in Supercritical Fluids.- 3.4.2 Solubility and Chemical Structure.- 3.4.2.1 Hydrocarbons.- 3.4.2.2 Hydroxyl Compounds.- 3.4.2.3 Carboxylic Acids.- 3.4.2.4 Ethers.- 3.4.2.5 Esters.- 3.4.2.6 Aldehydes.- 3.4.2.7 Nitrogen-Containing Compounds.- 3.4.3 The Solubility Parameter.- 3.4.4 Theoretical Models.- 3.4.5 Influence of Cosolvents on Solubility: the Entrainer Effect.- 3.4.5.1 Clustering.- 3.4.5.2 Effect of the Cosolvent on Selectivity.- 3.4.6 Entrainer Effect of a Second Solute.- 3.4.7 Solubility near a UCEP.- 3.5 Transport Phenomena.- 3.5.1 Desorption of Adsorbed Species.- 3.5.2 Diffusion in the Solid.- 3.5.2.1 The Spherical Model.- 3.5.2.2 The Infinite Slab Model.- 3.6 Factors Influencing Supercritical Leaching.- 3.6.1 Properties of the Supercritical Fluid.- 3.6.2 Properties of the Solid.- 3.6.3 Properties of the Solute.- 3.6.4 Presence of a Modifier.- 3.6.5 Additives.- 3.6.6 Derivatization.- 3.6.7 Temperature.- 3.6.8 Dynamic Factors.- References.- 4 The Analytical-Scale Supercritical Fluid Extractor.- 4.1 Introduction.- 4.2 The Supercritical Fluid Extractor: A Broad View.- 4.3 Basic Elements of a Supercritical Fluid Extractor.- 4.3.1 The Fluid Reservoir.- 4.3.1.1 Description.- 4.3.1.2 Connection to the Extractor.- 4.3.1.3 Functioning, Cautions.- 4.3.1.4 Measurement of the Cylinder Contents.- 4.3.2 The propulsion system.- 4.3.2.1 Single Systems.- 4.3.2.2 The Need for a Dual Propulsion System: Use of Modifiers.- 4.3.3 The Extraction Chamber.- 4.3.3.1 General Features.- 4.3.3.2 Cell Size.- 4.3.3.3 Sample Size to Cell Volume Ratio.- 4.3.3.4 Cell Geometry.- 4.3.3.5 Special Cells.- 4.3.3.6 Multi-Extraction Systems.- 4.3.3.7 Performance of Extraction Chambers.- 4.3.4 The Depressurization System.- 4.3.4.1 Types of Restrictors.- 4.3.4.2 Problems Arising from Depressurization.- 4.3.5 Collection Systems.- 4.3.5.1 Types.- 4.3.5.2 Special Collection Systems.- 4.3.6 Thermostating.- 4.3.7 Ancillary Components.- 4.4 Extraction Modes.- 4.5 Off-Line Coupled SF Extraction/Detection.- 4.6 On-Line Coupled SF Extraction/Detection.- 4.6.1 Types of Interfaces Used.- 4.6.2 Coupled SFE/Gas Chromatography.- 4.6.3 Coupled SFE/SFC.- 4.6.4 Coupled SFE/HPLC.- 4.6.5 Comparison of SFE Hyphenated Techniques with GC, SFC and HPLC.- 4.6.6 Other Hyphenated Techniques.- 4.7 Comparison of the Off-Line and On-Line Modes.- 4.8 Commercially Available Supercritical Fluid Extractors.- References.- 5 Analytical Applications of Supercritical Fluid Extraction.- 5.1 Introduction.- 5.2 Variables Affecting Extraction Quality.- 5.2.1 Nature and Composition of the Extractant.- 5.2.2 Pressure.- 5.2.3 Temperature.- 5.2.4 Flow-Rate.- 5.2.5 Extraction Time.- 5.2.6 Sample and Analyte Properties.- 5.2.7 Collection Systems.- 5.2.8 In-situ Derivatization.- 5.2.9 Other Factors.- 5.2.10 Quality Parameters.- 5.3 Sequential Extractions.- 5.4 General Applications of SFE.- 5.4.1 Types of Samples.- 5.4.1.1 Solid Samples.- 5.4.1.2 Liquid Samples.- 5.4.1.3 Gaseous Samples.- 5.4.1.4 Sample Size.- 5.4.2 Types of Analytes.- 5.4.3 Scope of Application of SFE.- 5.5 SFE and Other Extraction Techniques.- 5.5.1 Advantages of Supercritical Fluid Extraction.- 5.5.2 Disadvantages of Supercritical Fluid Extraction.- 5.6 Trends in SFE.- References.
224 citations
TL;DR: Data support the hypothesis that the nitrate transport system in C. reinhardtii contains at least two protein components encoded by the nar-2 and nar-3 genes, and the deduced amino acid sequences showed a very significant identity with that of the Nitrate transporter gene from Aspergillus nidulans.
Abstract: Summary
The Chlamydomonas reinhardtii nar-2, nar-3, and nar-4 genes, which are within a nitrate-regulated gene cluster containing the nitrate reductase structural gene nit-1, have been related to nitrate transport. Mutant strains defective in nitrate transport and having an active nitrate reductase have been genetically constructed. Their nitrate non-utilizing phenotype has been directly complemented by transformation using the pCO-5 plasmid which carries the nar-2, nar-3, and nar-4 clustered genes. Integration of pCO-5 DNA in the genome of nitrate transport mutants resulted in the expression of these nar transcripts and the recovery of a high affinity nitrate transport activity. Complementation of the nitrate non-utilizing phenotype of the constructed strains was also achieved by co-transformation with plasmids containing nar-2 and nar-3 genes or nar-2 and nar-4, but not with single plasmids containing each individual gene. In addition, DNA sequences of a practically complete cDNA of nar-3 and a partial one of nar-4 have been generated and the deduced amino acid sequences showed a very significant identity with that of the nitrate transporter gene (crnA) from Aspergillus nidulans. These data strongly support the hypothesis that the nitrate transport system in C. reinhardtii contains at least two protein components encoded by the nar-2 and nar-3 genes. The nar-4 gene would produce a protein with a high identity to that of nar-3.
180 citations
TL;DR: In this article, the effect of heavy metals on the induction of enhanced root Fe(III) reductase by 11 -d-old Fe-deficient cucumber (Cucumis sativus L. cv. Ashley).
Abstract: Heavy metals are known to induce Fe chlorosis in different plant species. Heavy-metal-induced chlorosis is generally correlated with low plant Fe contents, suggesting effects of heavy metals on Fe mobilization and uptake. Under Fe-deficient conditions, dicotyledonous plants enhance root Fe(III) reductase activity, thus increasing the capacity to reduce Fe(III) to Fe(II), the form in which roots absorb Fe. We studied the effect of several heavy metals (Mn, Pb, Zn, Mo, Ni, Cu, and Cd) on the induction of enhanced root Fe(III) reductase by 11 -d-old Fe-deficient cucumber (Cucumis sativus L. cv. Ashley). The effect of these heavy metals on the function of the induced Fe(III) reductase was also investigated. Results showed that some heavy metals can inhibit both the induction and function of root Fe(III) reductase. Ni, at 20 μM, and Cu and Cd, at 5 μM concentration or higher, severely inhibited the induction of root Fe(III) reductase while Mn, Pb, Zn, and Mo had little effect, even at concentrations higher than 20 μM. Function of the induced root Fe(III) reductase only was negatively affected by Cu and Ni
170 citations
TL;DR: Evidence is shown that ethylene plays a role in the development of Fe-deficiency stress responses, since when ethylene synthesis or action was inhibited, the responses were also inhibited, and when a precursor of ethylene (ACC) was added, theResponses were increased.
Abstract: Most dicotyledonous species respond to Fe deficiency by developing several mechanisms known as Fe-deficiency stress responses. To study the regulation of these responses, young cucumber plants (Cucumis sativus L. cv Ashley) were grown in nutrient solution for 11 d, being deprived of Fe during the last 4 or 5 d. Inhibitors of ethylene synthesis (2 or 10 [mu]M aminoethoxyvinylglycine; 10 or 20 [mu]M aminooxyacetic acid; 1, 2, 5, or 10 [mu]M Co2+ as CoCl2) or action (50, 200, or 800 [mu]M Ag+ as silver thiosulfate) were added to the nutrient solution at different times during this period of growth with no Fe. After this period, the reduction of Fe3+ ethylenedi-aminetetraacetate by the roots of entire plants was measured with ferrozine by reading the absorbance at 562 nm after 2 h. The presence of the ethylene inhibitors in the nutrient solution inhibited the Fe-deficiency stress responses ferric-reducing capacity and subapical root swelling. In another experiment, the addition of 1 [mu]M 1-aminocyclopropane-1-carboxylic acid (ACC), a precursor of ethylene synthesis, to the nutrient solution of plants having low ferric-reducing activity increased notably the ferric-reducing capacity and subapical root swelling. Here we show evidence that ethylene plays a role in the development of Fe-deficiency stress responses, since when ethylene synthesis or action was inhibited, the responses were also inhibited, and when a precursor of ethylene (ACC) was added, the responses were increased.
117 citations
TL;DR: The results are compatible with the presence in bovine chromaffin cells of a Q‐like Ca2+ channel which has a prominent role in controlling exocytosis and suggest that Q‐ and L‐type Ca 2+ channels, but not N‐ or P‐types are localized near exocyTotic active sites in the plasmalemma.
115 citations
TL;DR: In this paper, the effect of morphology and other crystal properties of hematite on phosphorous adsorption and desorption was studied, and it was shown that the more platy the crystal, the lower the proportion of high-affinity sites, supporting the hypothesis that the P-adsorbing faces are the nonbasal ones.
109 citations
TL;DR: Results indicate that macrophages are needed for Leydig cell development and for the Leydigs cell response to hCG during postnatal maturation.
Abstract: Testicular macrophages in rats were selectively depleted by an intratesticular injection of liposomes containing dichloromethylene diphosphonate into the right testis to study the possible role of these macrophages during the prepubertal development of Leydig cells. The contralateral testes were injected with 0.9% NaCl and served as controls. The animals were injected with the liposomes and NaCl at 5, 10, 15, 20 or 25 days of age. In macrophage-depleted testes, Leydig cell development was inhibited in the animals injected at 5, 10 or 15 days of age. At 35 days of age, the testis was repopulated with macrophages and Leydig cells also developed. Rats treated at 20 or 25 days of age, when Leydig cells were already present in low numbers, did not show any further increases in the number of Leydig cells up to 35 days of age. To study whether the effects of gonadotrophins on Leydig cell development require the presence of macrophages, 21-day-old rats, injected 3 days before with liposomes (right testis) and NaCl (left testis), were treated with 75 iu human FSH kg-1 bodymass day-1, 10 iu hCG per rat day-1, combined hFSH and hCG, or vehicle (PBS with 0.5% BSA) for 6 days. Treatment with hCG induced a sevenfold increase in the number of Leydig cells in the left (macrophage-containing) testis, whereas no increase was found in the right (macrophage-depleted) testis. These results indicate that macrophages are needed for Leydig cell development and for the Leydig cell response to hCG during postnatal maturation.
103 citations
TL;DR: The Pocho volcanic field in Argentina as discussed by the authors contains an older (7.9 to 4.5 Ma) high-K and a younger (5.3± 0.7 Ma) shoshonitic series.
Abstract: The Late Miocene (7.9 to 4.5 Ma) Pocho volcanic field in Argentina occurs 700 km east of the Chile trench over the modern shallowly dipping Andean Wadati-Benioff zone near 32° S latitude in Argentina. The field is located in the Sierra de Cordoba which is the easternmost Laramide-style, block-faulted range in the Sierras Pampeanas (Pampean ranges). The arrival of the shallowly dipping slab initiated both volcanism and the uplift of the Sierra de Cordoba. Pocho rocks (52% to 68% SiO2; FeO*/MgO>2.2) comprise an older (7.5±0.5 Ma) high-K and a younger (5.3±0.7 Ma) shoshonitic series. Mineralogic data and fractionation models show that crystallization occurred under hydrous, oxidizing conditions, which were most extreme in the high-K series. An unusual pattern of successively lower REE at higher SiO2 concentrations can be modeled by sphene, apatite and amphibole removal. An arc-like trace element signature attributed to an arc component is strongest in the younger shoshonitic series. An important depleted lower crustal/mantle lithospheric source component in both series is indicated by non-radiogenic Sr and Pb isotopic ratios at ɛNd= 0 to + 2, low Rb/Sr ratios, and low U and Th concentrations. This depleted signature contrasts with the enriched one in potassic back-arc Central Volcanic Zone (CVZ) lavas over the steeper subduction zone to the north and is attributed to several processes in the shallow subduction zone. First, deep crustal (MASH) processes in the nearly normal thickness crust beneath Pocho incorporated depleted Proterozoic basement components, and not complexly mixed structurally thickened crustal components as in the CVZ. Second, the association of Pocho volcanism with the arrival of the slab allowed little time for modification of the mantle by subduction components. Third, Miocene shallowing of the subduction zone beneath the “flat-slab” required thinning of both the astenosphere and the subcontinental lithosphere. Thus, an important subcrustal component could be from blocks removed from the base of the lithosphere to the west and recycled into the asthenosphere. Similar magmatic sources would have existed during Laramide shallow subduction in western North America.
101 citations
TL;DR: The results obtained demonstrate that this method could be useful for measurement of the glutathione redox status in fish liver and are consistent with those reported for other fish.
88 citations
87 citations
TL;DR: The ligand-activated oxidase in the plasma membrane introduces a new basis for control of signal transduction in cells and the redox state of the quinone in the oxidase is proposed to control tyrosine kinase either by generation of H2O2 or redox-induced conformational change.
TL;DR: Only a small part (14%) of the observed response in RUE could be attributed to greater photosynthesis resulting from greater N content and its distribution in the canopies, while the major part comprised undefined responses of partitioning of biomass to roots and to losses by respiration.
TL;DR: The dependence of phytoavailability of adsorbed phosphate on mineral type and properties has not been established as mentioned in this paper, but it has been shown that goethites usually have higher relative affinity for phosphate than hematites, suggesting that phosphate could be more available to plants in hematitic than in similar goethitic soils.
Abstract: Iron (hydr)oxides are important phosphate adsorbents in soils. However, the dependency of phytoavailability of adsorbed phosphate on mineral type and properties has not been established. To examine the influence of mineralogy, one ferrihydrite, two hematites, and two goethites were prepared. They differed widely in morphology (from euhedral crystals to granular aggregates), specific surface area (15–266 m2 g−1) and microporosity (0–87% of total surface area). Their relative affinity for phosphate, which is inversely related to the concentration exponent in the Freundlich equation, b, decreased in the order goethite (b=0.11, 0.09)> hematite (b=0.13, 0.17)> ferrihydrite (b=0.21). Phytoavailability of the adsorbed phosphate was studied by growing sunflower (Helianthus annuus L.) in pots containing suspensions of the phosphated Fe (hydr)oxides in equilibrium with a concentration of 1 mg P L−1. The fraction of the adsorbed phosphate that was phytoavailable, B
1, (1) was lower for goethite (B
1=0.43, 0.38) than for hematite (B
1=0.73, 0.49) and ferrihydrite (B
1=0.79), (2) was not negatively affected by microporosity, and (3) decreased, in general terms, with increasing relative affinity for phosphate. Similar trends were observed for the production of dry matter. These results, together with previous reports showing that goethites usually have higher relative affinity for phosphate than hematites, suggest that phosphate could be more available to plants in hematitic than in similar goethitic soils.
TL;DR: The results indicate that ascorbate has a cytotoxic effect by killing cells directly, rather a cytostatic one.
Abstract: Ascorbate, an essential nutrient in humans, primates, and guinea pig, is involved in many cellular functions. Ascorbate also modulates cell growth and differentiation. Ascorbate can reduce or stimulate the growth of tumor cells, depending on the cell type. The inhibitory effect is not specific for the biological active isomerl-ascorbate, and isoascorbate andd-ascorbate are more effective in reducing cell growth thanl-ascorbate. These results indicate that ascorbate has a cytotoxic effect by killing cells directly, rather a cytostatic one. However, onlyl-ascorbate is able to stimulate cell growth, but the mechanism of this stimulation is still unknown.l-Ascorbate stimulates thein vitro differentiation of several mesenchyme-derived cell types by altering the expression of multiple genes as the cell progresses through specific differentiation programs. Stimulation of collagen matrix at gene transcription, mRNA stabilization, hydroxylation, and secretion is a key role forl-ascorbate.l-Ascorbate also prevents cell transformation by stabilization of the differentiated state and cooperates with other agents to induce differentiation in a leukemia cell line.
TL;DR: Dry matter partitioning and yield formation are key points for successful simulation of seed yield and increasing potential yield of the sunflower should focus on the improvement of the harvest index of the long-cycle hybrids.
TL;DR: The survival of constitutive microflora was studied in one batch of fermented milk containing bifidobacteria produced in Spain during storage at 7°C and the pH values were between 4.57 and 3.81.
TL;DR: A continuous preconcentration method for the determination of trace copper in waters was developed and the results obtained show the usefulness of the proposed method.
TL;DR: Current data are discussed on the basis of the modulation of the plasma membrane energetic state derived from the ascorbate-induced hyperpolarization and the activity of an intrinsic transplasmalemma ascorBate-regenerating enzyme.
Abstract: Ascorbate and related enzymes are involved in the control of several plant growth processes. Ascorbate modulates cell growth by controlling (i) the biosynthesis of hydroxyproline-rich proteins required for the progression of G1 and G2 phases of the cell cycle, (ii) the cross-linking of cell wall glycoproteins and other polymers, and (iii) redox reactions at the plasma membrane involved in elongation mechanisms. The effect of ascorbate on onion root elongation is reviewed here. The ascorbate free radical induces a high vacuolization responsible for elongation. This effect may be dependent on the activity of the redox system linked to the plasma membrane. Current data are discussed on the basis of the modulation of the plasma membrane energetic state derived from the ascorbate-induced hyperpolarization and the activity of an intrinsic transplasmalemma ascorbate-regenerating enzyme.
TL;DR: The data strongly suggest that NR negatively autoregulates its own expression and that of nar genes, and shows a strong positive effect on the accumulation of nit-1 gene transcripts.
Abstract: The mRNA accumulation pattern of the Chlamydomonas reinhardtii nitrate assimilation-related gene cluster has been elucidated. In ammonium-grown wild-type cells, nit-1 (nitrate reductase, NR), nar-1, nar-2 and nar-3 (nitrate transporter) genes showed very similar kinetics of expression when transferred to nitrate medium. Transcripts of all these genes accumulated transiently in ammonium-grown wild-type cells after a one-hour incubation in nitrogen-free medium, and practically disappeared at about 2 hours. Mutant strains lacking functional nitrate reductase showed similar accumulation kinetics of these transcripts during both nitrate induction and derepression in nitrogen-free media. In contrast to the other nar transcripts, that nar-4, a gene sharing similar sequences with nar-3, accumulated in small amounts in wild-type cells, and only increased after a long nitrate induction period. Nitrate and light showed a strong positive effect on the accumulation of nit-1 gene transcripts. Acetate as a carbon source allowed accumulation of nit-1 mRNA in the dark, indicating the existence of interactions between light and carbon metabolism in nit-1 gene expression. Our data strongly suggest that NR negatively autoregulates its own expression and that of nar genes.
TL;DR: The results indicate that macrophages are needed for the differentiation of Leydig cells from mesenchymal precursors, as well as for the proliferative activity of the newly formed Leydigs cells, possibly through the secretion of essential growth factors.
Abstract: Testicular macrophages were selectively depleted in the right testes of adult rats by an intratesticular injection of dichloromethylene diphosphonate-containing liposomes (Cl2MDP-lp), whereas the left testes were injected with 0.9% NaCl and served as control. Before or after Leydig cell destruction with ethylene dimethane sulfonate (EDS), treatment with Cl2MDP-lp/NaCl was given at different times to study the requirements of macrophages in the different stages of Leydig cell regeneration. On day 30 after EDS treatment, new Leydig cells were abundant in the left, macrophage-containing testes. However, in the right, macrophage-depleted testes, the number of Leydig cells was related to the time elapsed between EDS treatment and macrophage depletion. When macrophages were depleted on day 10 before or on days 4 or 10 after EDS treatment, new Leydig cells were nearly absent at 30 days. However, when macrophages were depleted on days 16 or 22 after EDS treatment, Leydig cells were found at 30 days, but their numbers were equivalent to the number of Leydig cells that were already present in EDS-treated animals at the time the macrophages were depleted. These results indicate that macrophages are needed for the differentiation of Leydig cells from mesenchymal precursors, as well as for the proliferative activity of the newly formed Leydig cells, possibly through the secretion of essential growth factors.
TL;DR: Highly purified plasma membrane fractions obtained from onion (Allium cepa L.) roots were used as a source for purification of redox proteins and dehydrogenase II was specific for NADH and exhibited maximal activity with ferricyanide.
Abstract: Highly purified plasma membrane fractions were obtained from onion (Allium cepa L.) roots and used as a source for purification of redox proteins. Plasma membranes solubilized with Triton X-100 contained two distinct polypeptides showing NAD(P)H-dependent dehydrogenase activities. Dehydrogenase I was purified by gel filtration in Sephacryl S-300 HR, ion-exchange chromatography in DEAE-Sepharose CL-6B, and dye-ligand affinity chromatography in Blue-Sepharose CL-6B after biospecific elution with NADH. Dehydrogenase I consisted of a single polypeptide of about 27 kD and an isoelectric point of about 6. Dehydrogenase II was purified from the DEAE-unbound fraction by chromatography in Blue-Sepharose CL-6B and affinity elution with NADH. Dehydrogenase II consisted of a single polypeptide of about 31 kD and an isoelectric point of about 8. Purified dehydrogenase I oxidized both NADPH and NADH, although higher rates of electron transfer were obtained with NADPH. Maximal activity was achieved with NADPH as donor and juglone or coenzyme Q as acceptor. Dehydrogenase II was specific for NADH and exhibited maximal activity with ferricyanide. Optimal pH for both dehydrogenases was about 6. Dehydrogenase I was moderately inhibited by dicumarol, thenoyltrifluoroacetone, and the thiol reagent N-ethyl-maleimide. A strong inhibition of dehydrogenase II was obtained with dicumarol, thenoyltrifluoroacetone, and the thiol reagent p-hydroxymercuribenzoate.
TL;DR: The results suggest that chlorate and TMAO can be used as ancillary oxidants by Rhodobacter strains and that a single enzyme could be responsible for nitrate and chlorate reduction inR.
Abstract: Chlorate or trimethylamine-N-oxide (TMAO) added to phototrophic cultures ofRhodobacter sphaeroides DSM 158 increased both the growth rate and the growth yield although this stimulation was not observed in the presence of tungstate. This strain, exhibited basal activities of nitrate, chlorate, and TMAO reductases independently of the presence of these substrates in the culture medium, and nitrate reductase (NR) activity was competitively inhibited by chlorate. Phototrophic growth ofRhodobacter capsulatus B10, a strain devoid of NR activity, was inhibited only by 100 mM chlorate. However, growth of the nitrate-assimilatingR. capsulatus strains E1F1 and AD2 was sensitive to 10mm chlorate, and their NR activities were not inhibited by chlorate. Both NR and chlorate reductase (CR) activities of strain E1F1 were induced in the presence of nitrate or chlorate respectively, whereas strain AD2 showed basal levels of these activities in the absence of the substrates. A basal TMAO reductase (TR) activity was also observed when these strains ofR. capsulatus were cultured in the absence of this electron acceptor. These results suggest that chlorate and TMAO can be used as ancillary oxidants byRhodobacter strains and that a single enzyme could be responsible for nitrate and chlorate reduction inR. sphaeroides DSM 158, whereas these reactions are catalyzed by two different enzymes inR. capsulatus E1F1 and AD2.
TL;DR: The results suggest that PACAP38-positive cells are present within lymphoid tissues and may represent a lymphocyte-like cell subpopulation that has a potential role in cell-to-cell interactions in the immune system and in the integrated communication between neuroendocrine and immune systems.
Abstract: Pituitary adenylate cyclase activating peptide (PACAP) is a novel peptide isolated from the ovine hypothalamus. PACAP exists in 2 molecular forms with 27 (PACAP27) or 38 (PACAP38) amino acid residues. PACAP localization was studied by immunohistochemical methods in central (bone marrow and thymus) and peripheral (spleen, lymph nodes and duodenal mucosa) lymphoid tissues with antisera raised against PACAP27 or PACAP38. PACAP-positive cells were found in all lymphoid tissues examined. These cells were highly positive for PACAP38 but were negative for PACAP27. Morphologically, they were small mononuclear cells with relatively scarce cytoplasm and lymphocyte-like features. PACAP38-positive cells were abundant in peripheral lymphoid tissues (i.e., mesenteric lymph nodes). In the duodenal mucosa, PACAP38-positive cells were located either in the lamina propria or epithelium. These results suggest that PACAP38-positive cells are present within lymphoid tissues and may represent a lymphocyte-like cell subpopulation that has a potential role in cell-to-cell interactions in the immune system and in the integrated communication between neuroendocrine and immune systems.
TL;DR: It is indicated that testicular macrophages are central to the proliferation and differentiation of new Leydig cells after EDS treatment, and the significance of paracrine regulatory mechanisms in rat testes is pointed out.
Abstract: Testicular macrophages were selectively eliminated with dichloromethylene diphosphonate-containing liposomes (Cl2MDP-lp) to study the role of these cells in the repopulation of Leydig cells after treatment with ethylene dimethane sulfonate (EDS). Right testes were injected with Cl2MDP-lp to deplete macrophages and left testes were injected with sodium chloride and served as controls. Injection of Cl2MDP-lp produced a 97% reduction in the number of macrophages 10 days after treatment. Twenty-one days after destruction of the existing Leydig cells with EDS, abundant differentiating Leydig cells were present in the left (macrophage-containing) testes. On the contrary, in the right (macrophage-depleted) testes, differentiating Leydig cells were scarce, and was 3% of that found in the control testes. The inhibition of Leydig cell repopulation in macrophage-depleted testes was more evident at 30 days after EDS treatment, when the number of Leydig cells in the right testes was 1% of that found in control testes. The lack of Leydig cell development was also indirectly shown by the lower mass and more atrophic seminiferous epithelium of the right testes, as well as the decreased weight of the ipsilateral epididymis compared with the left testes. These results indicate that testicular macrophages are central to the proliferation and differentiation of new Leydig cells after EDS treatment, and point out the significance of paracrine regulatory mechanisms in rat testes.
TL;DR: The relationship between an increase in vacuolar volume and stimulated nutrient uptake from ascorbate-free radical, resulting in enhanced root elongation is shown, suggesting that activation of a transplasma membrane redox system by ascorBate- free radical is involved in these responses.
Abstract: Long-term treatments with ascorbate free radical-stimulated glucose, fucose, sucrose, and nitrate uptake in Allium cepa roots. Glucose and fucose showed saturation kinetics in untreated roots, but after treatment with the ascorbate free radical, uptake was linear with time. Although the rates of nitrate and sucrose uptake increased after treatment with ascorbate free radical, the kinetics were similar to those observed in the controls. Ascorbate and dehydroascorbate inhibited nutrient uptake. The uptake rates for all nutrients increased throughout the 48-h period of pretreatment with ascorbate free radical. During the treatment an increase in the vacuole volume and tonoplast surface area also occurred. These results show the relationship between an increase in vacuolar volume and stimulated nutrient uptake from ascorbate-free radical, resulting in enhanced root elongation. These results suggest that activation of a transplasma membrane redox system by ascorbate-free radical is involved in these responses.
TL;DR: It was shown that quercetin and rutin, two flavonols present in beverages of plant origin, also exhibited weak genotoxic activity in the somatic cells of Drosophila.
TL;DR: In this article, a theoretical study of two-dimensional phase transitions taking place in electrode processes was carried out by using cyclic voltammetry, where the treatment used was applied on the assumption that the nucleation rate for the process is a function only of the concentration of nuclei of a critical size which depends on the overpotential.
TL;DR: The results support a model in which glucose-induced activation of H(+)-ATPase is mediated by a phosphatidylinositol-type signaling pathway triggering phosphorylation of the enzyme both by protein kinase C and one or more Ca2+/calmodulin-dependent protein kinases.
TL;DR: The results suggest partial compensation of the alternate habit by enhancement of female floral quality and an increase in fruit set when low levels of flowering occur.
TL;DR: Evaluating the potential role of adjunctive coronary stenting after initial recanalization in 30 patients with nonacute coronary total occlusion found that patients with initial successful results have an increased propensity toward restenosis or reocclusion.
Abstract: Percutaneous transluminal balloon angioplasty for chronic total occlusion of a coronary artery is associated with a primary success rate of about 60%. 1–3 This low success rate may be the result of failure in crossing the occlusion, or simply an unsatisfactory angiographic result after balloon inflation. In addition, patients with initial successful results have an increased propensity toward restenosis or reocclusion. 4,5 Stenting the recanalized segment in selected patients could theoretically improve the results of balloon angioplasty alone. 6 This report evaluates the potential role of adjunctive coronary stenting after initial recanalization in 30 patients with nonacute coronary total occlusion.