Showing papers by "University of Hohenheim published in 1985"
TL;DR: An ultra rapid and sensitive HPLC method for measuring individual free amino acids in biological fluids has been developed by using o-phthaldialdehyde/3-mercaptopropionic acid as derivatization agent and employing 3-micron-particle-size reversed-phase columns.
163 citations
TL;DR: On the basis of NMR data including NOE experiments, 13 C deuterium isotope shifts, and 13 C- 1 H long range coupling, the authors suggest structure 2 and 3 for azadirachtin, and 22,23-dihydro-23β-methoxyazadirachin, resp.
102 citations
TL;DR: This method can be used to accurately measure the pH gradient across the rhizosphere, even by distances less than 1 mm from the root surface, which could considerably affect microbial activity and solubility of mineral elements in the Rhizosphere and thus also mineral element uptake particularly on acid soils.
92 citations
TL;DR: The data strongly suggest that the developmental appearance of these polysialogangliosides is synchronized with the withdrawal of proliferating precursor cells from the mitotic cycle and differentiation to neurons.
84 citations
TL;DR: The effect of different temperatures on the senescence of ovules was investigated in 2 sweet and 3 sour cherry cultivars using a fluorescent-microscopic method and increasing temperature substantially shortened the viability of the ovules.
70 citations
01 Jan 1985
TL;DR: By inoculation with Azospirillum brasilense Ft 326 root elongation of Beta vulgaris ssp. cicla was stimulated and the number of the lateral roots was increased as mentioned in this paper.
Abstract: By inoculation with Azospirillum brasilense Ft 326 root elongation of Beta vulgaris ssp. cicla was stimulated and the number of the lateral roots was increased. The strain used is a mutant which produces more auxin than the wild strain Sp Cd from which it was obtained by Hartmann (Bayreuth). In these experiments the plants were cultivated in boxes filled with soil which were placed in an inclined position so that root growth was along a plexiglass plate which could be removed shortly for spraying. Application of IAA to wheat plants grown in the same way or to plants grown under sterile conditions in agar plates led to similar results. The dominating phytohormone determined by radioimmunoassay in the supernatant of the medium of Azospirillum was IAA. ABA was found in moderate amounts and cytokinins in traces only.
69 citations
TL;DR: The present study demonstrates the marked segmental heterogeneity of the basic electrical properties and suggests four different segmental organizations of large intestinal electrolyte transport.
Abstract: Electrical potential difference, short circuit current, tissue conductance, and unidirectional Na-fluxes were measured in four segments of the rabbit large intestine in vitro. Compared to the relatively tight, low conductance distal colon, caecum and proximal parts of the colon are leaky epithelia with high conductances. Net Na-absorption was highest in caecum, and then decreased gradually towards the distal colon, whereas potential and short circuit current where high in the caecum and proximal colon, low in the middle part of the colon, and high again in the distal colon. Unidirectional Na-fluxes of all four segments were different. The discrepancy between the short circuit current and net Na-absorption in the two segments of the proximal colon indicates electrogenic transport of other ions. 0.1 mM ouabain virtually abolished short circuit current and Na-absorption in all segments, whereas 0.1 mM amiloride was not effective in the caecum and the proximal colonic parts. The present study focuses on the comparative aspects of Na-transport. It demonstrates the marked segmental heterogeneity of the basic electrical properties and suggests four different segmental organizations of large intestinal electrolyte transport.
66 citations
TL;DR: A simple method for the effective, covalent, immobilization of porcine liver esterase ( PLE) is described and the application of this reagent for the preparation of chiral building blocks on a 50 – 500 mmol scale is demonstrated.
60 citations
TL;DR: In this article, a low-cost solar grape dryers were developed in the Institute of Agricultural Engineering of Hohenheim University and were tested in Greece in cooperation with the Crete Agricultural Research Center.
Abstract: Mass losses and low quality are the most serious disadvantages of traditional grape drying methods. For the production of high quality raisins an increase in the drying rate is required and the grapes should be protected from rain, dust and insects during drying. Under the terms of a joint German-Greek research program low-cost solar grape dryers were developed in the Institute of Agricultural Engineering of Hohenheim University and were tested in Greece in cooperation with the Crete Agricultural Research Center. The required data basis for optimizing solar grape dryers was obtained by additional laboratory tests measuring the influence of various drying parameters on drying rate and quality. Tests with the solar dryers have shown that it is possible to reduce the drying time and improve the quality significantly compared to the traditional drying methods. Also mass losses due to rain can be prevented.
52 citations
TL;DR: The results indicate better postoperative nitrogen economy in the OR group than in the control group, and Stimulation of insulin and growth hormone secretion may be contributing factors in the better nitrogen utilization.
51 citations
TL;DR: From the data, a new classification of breeds with long, medium and short skulls is presented.
Abstract: Skulls of 38 breeds were measured, and from the data a new classification of breeds with long, medium and short skulls is presented.
TL;DR: Cytokinesis is prevented to a great extent, resulting in the formation of binucleate cells which can additionally possess some micronuclei and the vimentin intermediate filament system was rearranged as a juxtanuclear complex after TriEL treatment.
TL;DR: In this paper, the effect of increasing oxygen concentrations (0, 5, 10 and 20 Vol% O2) on total denitrification and N20 release was studied in model experiments using a neutral pH loamy soil relatively rich in easily decomposable organic matter and supplied with nitrate (300 μg nitrate N/g dry soil).
Abstract: The effect of increasing oxygen concentrations (0, 5, 10 and 20 Vol% O2) on total denitrification and N20 release was studied in model experiments using a neutral pH loamy soil relatively rich in easily decomposable organic matter and supplied with nitrate (300 μg nitrate N/g dry soil). The sterilized soil was inoculated with three different denitrifying bacteria (Bacillus licheniformis,Aeromonas “denitrificans” andAzospirillum lipoferum) and incubated (80% WHC, 30°C). The gas volume was analysed for O2, CO2, N2O, NO and N2 by gas chromatography and the soil investigated for changes in ammonium, nitrite, nitrate, pH, total N and C as well as water-extractable C. WithB. licheniformis andAeromonas “denitrificans” total denitrification increased remarkably with increasing pO2 as the result of intensified mineralization.Azospirillum lipoferum, however, showed the highest activity at 5 vol% O2. WithB. licheniformis N2O was released only in anaerobic conditions and at 5 Vol% O2 (maximum) or 10 Vol% 02, but not at 20 Vol%, whereasAeromonas “denitrificans” produced N2O only in the presence of He gas (maximum) or at 5 Vol% O2. In contrast to these bacteria, N2O production withAzospirillum lipoferum was restricted to 10 Vol% O2 (maximum) and to 20 Vol% 02, with some traces at 5 vol% O2. With a certain set of conditions, total denitrification and N2O formation seem to be governed by the mineralization rate of the organisms in question. The increased demand for electron acceptors by a high turnover rate rather than the presence of anaerobic conditions seems to have determined the rate of denitrification.
TL;DR: The result suggest different effects on other cellular properties in addition to the effect on the presumably common pathway across the apical membrane on rabbit distal colon.
Abstract: The effects of pre-treatment in vivo with aldosterone and dexamethasone were investigated on rabbit distal colon. Apical Na-permeability and net sodium transport were measured in vitro. In this epithelium, Na-transport is entirely electrogenic. It can therefore be measured electrically as the fraction of short circuit current which is blockable by amiloride. The epithelia were studied in an Ussing chamber and the electrical values recorded by a computerized digital voltage clamp. Transepithelial parameters, and the transapical membrane parameters (in preparations depolarized from the serosal side) were investigated after treatment with the two hormones. Under transepithelial conditions, aldosterone and dexamethasone stimulated the short circuit current (Isc) from control (17.4 microA/cm2) to a similar degree (86.6 and 93.8 microA/cm2). However, whereas aldosterone did not alter the transepithelial resistance (RT) significantly, dexamethasone reduced RT from 357 to 167 omega X cm2. The stimulation of the potential difference (VT) under control condition (6.6 mV) was therefore significantly different between aldosterone (28.7 mV) and dexamethasone (16 mV). Mucosal amiloride (0.1 mM) inhibited Isc and VT completely under all conditions. Steady state current-voltage relations were obtained by voltage clamping the tissues in "staircase" increments before and after mucosal treatment with amiloride. As measured by the difference between these two states, Na-currents were calculated both for the transepithelial and the transapical condition. Intracellular Na-activity and apical Na-permeability were then calculated by the Nernst and Goldman-Hodgkin-Katz equations. These values were found to be increased after treatment with both hormones. Dexamethasone was a more potent stimulator of both values.(ABSTRACT TRUNCATED AT 250 WORDS)
TL;DR: A system for determining the length of spread of intestinal contractions has been developed and provides a more detailed representation of contractile patterns than other studies based on the conventional methods of analysis.
Abstract: The intestinal motility consists of local and propagative contractions. A system for determining the length of spread of intestinal contractions has been developed. The technique used for waveform recognition was based on the principle of peak detection. A computer program analysed the length of spread of contractile waves, their mean contractile force and their mean propagation velocity. The computer identified each waveform on the basis of pre-established threshold and timing criteria. A technique for fitting theoretical equations to experimental data (measured transit rate of ingesta against evaluated parameters) was used to prove the functional significance of the contractile patterns. The method provides a more detailed representation of contractile patterns than other studies based on the conventional methods of analysis.
TL;DR: The increase in sulphur-containing amino acids might be interpreted as a sign of an enhanced glutathione (GSH) catabolism, whereas the differing metabolic behaviour of branched chain amino acids (BCAA) suggests a specific reaction of valine in RA disease, similar to that in other catabolic diseases.
Abstract: Plasma amino acid concentrations have been investigated in 12 female patients with rheumatoid arthritis (RA), who were hospitalized for two 14-day periods, one of which included 7 days of total fas...
TL;DR: In this paper, the influence of light intensity on the behaviour of calves was examined, and it was found that the influence was clearest on social behaviour, and mainly on playing behaviour.
TL;DR: In this paper, pig liver alcohol dehydrogenase and pig-liver esterase were utilized for the asymmetric synthesis of such precursors, leading to the chiral γ-lactone (−)-11.
Abstract: Viridiene ((+)-6; (+)-(3R,4S)-3-((1Z)-1,3-butadienyl)-4-vinylcyclopentene) and aucantene ((+)-18; (+)-(4R,5R)-4-((1E)-1-propenyl)-5-vinylcyclohexene) are constituents of the pheromone bouquets of several brown algae species. Key synthons to the title compounds are optically active γ-lactones with known or experimentally determined absolute configurations. Horse liver alcohol dehydrogenase, which catalyses the oxidation of meso- and racemic non-meso diols to chiral lactones, and pig-liver esterase, which catalyzes the saponification of meso-diesters to chiral half-esters, were utilized for the asymmetric synthesis of such precursors. The racemic non-meso diol rac-1 is converted to the two stereoisomeric γ-lactones (+)-2 and (+)-3 which are readily separated. meso-Diol 12 is oxidized to the chiral γ-lactone (−)-11. Its enantiomer (+)-11 is obtained by enantioselective saponification of the meso-diester 9 with pig-liver esterase. Appropriately designed syntheses lead from these chiral intermediates to both enantiomers (+)- and (−)-6 of viridiene and (+)- and (−)-18 of aucantene. In addition, kinetically controlled reduction of the racemic aldehydes rac-5a and rac-15 with horse liver alcohol dehydrogenase offers a convenient alternative to the enantioselective preparation of the enantiomers of the two hydrocarbons 6 and 18. Chromatography of 6 on triacetylated cellulose as a stationary chiral phase confirms the enantiospecificity of the synthetic routes designed.
TL;DR: The phylogenetically primitive rove beetleDeleaster dichrous (Grav.) (Oxytelinae) has been shown for the first time to possess two pairs of neighboring abdominal glands which are depleted simultaneously on molestation, indicating a clear evolutionary trend at the micromolecular level.
Abstract: The phylogenetically primitive rove beetleDeleaster dichrous (Grav.) (Oxytelinae) has been shown for the first time to possess two pairs of neighboring abdominal glands which are depleted simultaneously on molestation. The morphology of these glands is described. The defensive constituents of theDeleaster glands were elucidated directly from the mixtures by gas chromatographic-mass spectroscopic methods and microchemical reactions. The paired whitish glands secrete iridodial, which polymerizes on exposure to air to form an adhesive that probably deters small predatory arthropods. The red gland system ofD. dichrous contains the toxicp-toluquinone and a variety of isopropyl andsec-butyl esters. Artificial quinoid ester mixtures simulating the secretion ofD. dichrous showed only weak effects on mortality ofLucilia larvae in comparison with more effective secretions of phyiogenetically derived Oxytelinae. The secretion of the primitive genusDeleaster is characterized chemotaxonomically by β, γ-unsaturated C12 acids and esters, which are postulated as precursors for the characteristic defensive compounds of the derived species, thus indicating a clear evolutionary trend at the micromolecular level.
01 Jan 1985
TL;DR: In this article, the role of pH and oxygen partial pressure (a function of moisture tension) on the long-term rate of gaseous nitrogen (N2O-N + N2) production from both natural and fertilized soils was investigated.
Abstract: It has been widely accepted that the relative amount of N2O from soils may be favoured by acid rather than neutral or alcaline conditions, and/or by increasing the oxygen tension of the system concerned. The former observation has been ascribed to the relative sensitivity of N2O-reductase to an increased proton activity, whereas the latter suggests that O2 becomes increasingly a competitive electron acceptor to nitrate resulting in an incomplete denitrification. Interest in conditions that affect the production of N2O has been stimulated by the concern about the possible destruction of stratospheric ozone as a result of the increased use in mineral nitrogen fertilizers. In soil and waters denitrification losses depend on amount and type of energy source, temperature, oxygen diffusion rate, nitrate availability and pH, all factors that are subject to continuous changes and interactions. However, among these factors, pH and oxygen partial pressure (a function of moisture tension) are thought to be key factors that enhance the relative amounts of N2O particularly at high amounts of nitrate (Focht, 1974; Knowles, 1981, 1982). Estimates of the total quantity of gaseous nitrogen (N2O-N + N2) released annually from soil and water sources are still scattered and tentative, but in situ field measurements of N2O (with and without acetylene inhibition) will contribute increasingly to the knowledge of denitrification (Focht, 1978; Knowles, 1982). Results from the acetylene inhibition technique, however, should be considered with care, since C2H2 may reach only a part of the N2O-reductases (Yeomans and Beauchamp, 1978), partially inhibit N2O-reductase itself (Lensi and Chalamet, 1979; 1982), accelerate the reduction of nitrate into N2O (Lensi and Chalamet, 1982) or even stimulate denitrification by acting as an energy source (Yeomans and Beauchamp, 1982; Haider et al., 1983). Further, N2O release from soil varies with time, climatic and envrionmental conditions (Letey et al., 1980; Ottow and Fabig, 1984) which make long-term measurements inevitable. Before accurate and reliable predictions are made on the possible effects of agricultural fertilizer practices, more basic information is needed on (1) the long-term rate of N20 production (relative to total denitrification) from both natural and fertilized soils and (2) on those environmental conditions that determine essentially incomplete transformation of nitrate into N20. In order to elucidate the effect of one single ecological factor on the relative amount of N20, model experiments under defined conditions are quite appropriate. In the present paper, such model experiments were made both with soils and liquid cultures in order to determine the role of pH and p02 on the relative amounts of N20 in the presence of high nitrate concentrations.
TL;DR: Based on theoretical and policy considerations, two criteria for a feasible procedure to detect misleading advertising are derived in this article, which is the basis for this paper. But these criteria are not applicable to all advertising types.
Abstract: Based on theoretical and policy considerations, two criteria for a feasible procedure to detect misleading advertising are derived. Current concepts for detecting misleading advertising are reviewe...
TL;DR: The combination of ultra high vacuum scanning electron microscopy with spectroscopy of the emitted electrons gives new possibilities for surface analysis as mentioned in this paper, and recent results in secondary, Auger, ionization loss, and elastic peak electron spectroscope.
TL;DR: Aerobic spore-forming bacteria were isolated from plant tissue cultures from a commercial plant cultivation station and found to be a detrimental infectant as a serious consequence of the heat-resistance of the endospores of Bacillus circulans.
Abstract: Aerobic spore-forming bacteria were isolated from plant tissue cultures from a commercial plant cultivation station Bacillus circulans was found to be a detrimental infectant as a serious consequence of the heat-resistance of the endospores of these bacteria They were extremely motile, utilized several growth-promoting factors, and could be eliminated by early microscopical identification, killing by heat treatment, or by using antibiotics or disinfecants
TL;DR: The citrate synthases from both thermoacidophilic archaebacteria resembled more closely the enzymes found in Gram-positive eubacteria and in eukaryotes rather than the enzymes from Gram-negative eub bacteria.
TL;DR: Optimization of peptide synthesis is significantly improved by this novel method, which enables simultaneous monitoring of the reaction products and contaminating inorganic ions during synthesis and purification.
TL;DR: Differences in puffing and developmental Puffing sequences of the three salivary gland lobes were investigated from mid fourth larval instar to pupation and compared with the puffing pattern of the Malpighian tubules.
Abstract: A detailed map of the salivary gland chromosomes ofAcricotopus lucidus is presented. Differences in puffing and developmental Puffing sequences of the three salivary gland lobes were investigated from mid fourth larval instar to pupation and compared with the puffing pattern of the Malpighian tubules. The intraglandular differentiation is quite extensive; the differences in the pattern of gene activity between the anterior lobe and the main and side lobes are as great as between the salivary gland and the Malpighian tubules. In the main and side lobes all developmental puffing changes proceed synchronously whereas in the anterior lobe both asynchronous and synchronous changes occur. In the anterior lobe the asynchronous regression of BR 3 and BR 4 is followed by a characteristic sequence of activation and inactivation of puffs.
TL;DR: In this article, the LAMMA 500 laser microprobe mass analyser was used for the analysis of single bacterial cells and the results showed that high laser power densities should be used for vaporization and ionization of the bacteria.
01 Jan 1985
TL;DR: Ion transport across lower intestinal epithelia has been studied most frequently on two mammals: rat and rabbit, and effects of adrenocortical steroids on the sodium transport have predominantly been reported in these two species.
Abstract: Ion transport across lower intestinal epithelia has been studied most frequently on two mammals: rat and rabbit, and effects of adrenocortical steroids on the sodium transport have predominantly been reported in these two species.
TL;DR: This enzyme, the arogenate dehydrogenase, has been purified for the first time in a 5‐step procedure to homogeneity as confirmed by electrophoresis.