Showing papers by "University of Göttingen published in 1983"

Studies on dissimilatory sulfate-reducing bacteria that decompose fatty acids

Abstract: Gliding motility, ultrastructure and nutrition of two newly isolated filamentous sulfate-reducing bacteria, strains 5ac10 and 4be13, were investigated. The filaments were always attached to surfaces. Growth was supported by addition of insoluble aluminium phosphate or agar as substrata for gliding movement. Electron microscopy of ultrathin sections revealed cell walls characteristic of Gramnegative bacteria; the undulated structure of the outer membrane may pertain to the translocation mechanism. Intracytoplasmic membranes were present. Acetate, higher fatty acids, succinate or fumarate served as electron donors and carbon sources. Strain 5ac10 grew also with lactate, but not with benzoate that was used only by strain 4be13. Strain 5ac10 was able to grow slowly on H2 plus CO2 or formate in the presence of sulfate without additional organic carbon source. The capacity of complete oxidation was shown by stoichiometric measurements with acetate plus sulfate. Both strains contained b- and c-type cytochromes. Desulfoviridin was detected only in strain 5ac10. The two filamentous gliding sulfate reducers are described as new species of a new genus, Desulfonema limicola and Desulfonema magnum.

Theory of Thermal Unimolecular Reactions in the Fall‐off Range. II. Weak Collision Rate Constants

Abstract: The master equation of thermal unimolecular reactions in the fall-off range has been solved for a number of representative molecular systems. Weak collision broadening factors F**W**C(k// /k// infinity ) are derived and represented empirically. Weak collision efficiencies beta //c for the low pressure range are calculated for very high temperatures. Combined with earlier representations (part I) of strong collision broadening factors F**S**C(k//0/k// infinity ), compact empirical expressions for the rate coefficient in the full fall-off range are proposed. These expressions are useful for data representation and modeling of complex reaction system which involve isomerization, dissociation and recombination reactions.

Methanococcus jannaschii sp. nov., an extremely thermophilic methanogen from a submarine hydrothermal vent

Abstract: A new extremely thermophilic methane-producing bacterium was isolated from a submarine hydrothermal vent sample collected by a research team from the Woods Hole Oceanographic Institution using the manned submersible ALVIN. The sample was obtained from the base of a “white smoker” chimney on the East Pacific Rise at 20° 50′ N latitude and 109° 06′ W longitude at a depth of 2600 m. The isolate was a motile irregular coccus with an osmotically fragile cell wall and a complex flagellar system. In defined medium with 80% H2 and 20% CO2, the isolate had a doubling time of 26 min at 85° C. The pH range for growth was 5.2 to 7.0 with an optimum near 6.0. NaCl was required for growth with an optimum of 2 to 3% (w/v). The mol % G+C was 31%. In cell-free extracts, methane formation from methylcoenzyme M was temperature-dependent, and H2 or formate served as electron donors. Methane formation from H2 and CO2 occurred at a much lower rate. Oligonucleotide cataloging of the 16S ribosomal RNA established the isolate as a new species of the genus Methanococcus and the name Methanococcus jannaschii is proposed. The isolation of M. jannaschii from a submarine hydrothermal vent provides additional evidence for biogenic production of CH4 from these deep-sea environments.

Collisional deactivation of vibrationally highly excited polyatomic molecules. II. Direct observations for excited toluene

Abstract: Vibrationally highly excited toluene molecules with 52 000 cm−1 of vibrational energy have been prepared by UV laser excitation of the isomer cycloheptatriene and subsequent isomerization. The collisional loss of energy from the excited toluene molecules has been observed directly by monitoring hot UV absorption spectra. Direct measurements of the average energies 〈ΔE〉 transferred per collision have been made for about 60 different bath gases. For complex bath gases, 〈ΔE〉 values appear to be considerably smaller than those derived from earlier indirect measurements. 〈ΔE〉 was found not (or only slightly) to depend on the excitation energy.

Penetration resistance and root growth of oats in tilled and untilled loess soil

Abstract: Penetration resistance, bulk density, soil water content and root growth of oats were intensively studied in a tilled and an untilled grey brown podzolic loess soil. Bulk density and penetration resistance were higher in the top layer of the untilled soil compared with the tilled soil. In the latter, however, a traffic pan existed in the 25–30 cm soil layer which had higher bulk density and penetration resistance than any layer of the untilled soil. Above the traffic pan, rooting density (cm root length per cm3 of soil) was higher but below the pan it was lower than at the same depth in the untilled soil. Root growth was linearly related to penetration resistance. The limiting penetration resistance for root growth was 3.6 MPa in the tilled Ap-horizon but 4.6-5.1 MPa in the untilled Ap-horizon and in the subsoil of both tillage treatments. This difference in the soil strength-root growth relationship is explained by the build up of a continuous pore system in untilled soil, created by earthworms and the roots from preceding crops. These biopores, which occupy < 1% of the soil volume, can be utilized by roots of subsequent crops as passages of comparatively low soil strength. The channeling of bulk soil may counteract the possible root restricting effect of an increased soil strength which is frequently observed in the zero tillage system.

Turner syndrome: Spontaneous growth in 150 cases and review of the literature

Abstract: The spontaneous growth of 150 patients with Turner syndrome from three German centers-90 with 45,X0 constitution, 60 with other chromosomal abnormalities-has been analyzed. The mean adult height was found to be (n=14) 146.8 cm. It was observed that growth in these patients can be divided into four phases: (1) Intrauterine growth, which is retarded; (2) Height development, which is normal up to abone-age of about 2 years; (3) Between a bone-age of 2 and 11 years when stunting of growth is most marked; (4) After a bone-age of 11 years—the time at which puberty should normally start—the growth phase is prolonged, but total height gain is only little below normal levels. No difference in height could be observed between cases with X0 karyotype and other chromosomal variants. The data are compared with those in the literature.

Influence of phosphate and nitrate supply on root hair formation of rape, spinach and tomato plants

Abstract: Experiments with tomato, rape and spinach in nutrient solutions have shown that the formation of root hairs is strongly influenced by phosphate and nitrate supply. Decreasing the phosphate concentration of the nutrient solution from 100 to 2 μM P resulted in an increase of root hair length from 0.1–0.2 to 0.7 mm of the three plant species. Root hair density also increased by a factor of 2–4 when the P concentration was lowered from 1000 to 2 μM. The variation of these two root properties raised the root surface area by a factor of 2 or 3 compared to plants well supplied with P. Root hair length was closely related to the phosphate content of the root and shoot material. On the other hand, spinach plants grown in a split-root experiment produced root hairs in solutions of high P concentration (1000μM P) if the major part of the total root system was exposed to low P concentration (2 μM P). It is therefore concluded that the formation of root hairs does not depend on directly the P concentration at the root surface but on the P content of the plant.

Level of enzymes involved in acetate, butyrate, acetone and butanol formation by Clostridium acetobutylicum

Abstract: Clostridium acetobutylicum cells were collected from chemostats which were run at pH 4.3 or 6.0 and which produced either acetone-butanol or acetate-butyrate; they were used to determine the level of enzymes involved either in solvent or in acid formation. The highest activity of phosphotransacetylase, phosphotransbutyrylase, acetate kinase, and butyrate kinase was found in cells which carried out an acetate-butyrate fermentation; these enzymes were present in solvent-producing cells at a level of about 10–50% as compared to acid-producing cells. Hydrogenase activity was detectable in approximately the same amounts in both cell types; however, in solvent-producing cells it was only measurable following a lag-period. Butyraldehyde and butanol dehydrogenases were found in small amounts exclusively in solvent-producing cells. It was demonstrated that the formation of acetone was initiated by the action of a coenzyme A-transferase which transferred coenzyme A from acetoacetyl-CoA to either acetate or butyrate. This coenzyme A-transferase as well as acetoacetate decarboxylase were hardly detectable in acid-producing cells, but reached high levels in solvent producing cells. Similar changes of the activity of the enzymes mentioned were observed when a batch culture was shifted from acid to solvent formation.

Structural relationships between minor and major proteins of hepatitis B surface antigen.

Abstract: The minor glycoproteins from hepatitis B surface antigen, GP33 and GP36, contain at their carboxy-terminal part the sequence of the major protein P24 They have 55 additional amino acids at the amino-terminal part which are coded by the pre-S region of the viral DNA

A Role for Fructose 2,6-Bisphosphate in the Regulation of Sucrose Synthesis in Spinach Leaves

Abstract: The subcellular distribution of fructose 2,6-bisphosphate in spinach (Spinacia oleracea) leaves was studied using nonaqueous fractionation, showing that all, or almost all, is located in the cytosol. The amount of fructose 2,6-bisphosphate present in leaves during the diurnal cycle was measured and compared to the accumulation of starch and sucrose, and the amounts of selected phosphorylated intermediates in the leaf. Upon illumination, the level of fructose 2,6-bisphosphate decreases, but prolonged illumination leads to an increase in the level to above that found in the dark, which accompanies the onset of rapid accumulation of starch in the leaf.

A Concept of Forest Ecosystem Stability and of Acid Deposition as Driving Force for Destabilization

Abstract: A theory is proposed which explains the acidification and alcalinization of soils, respectively, as consequence of the discoupling of the ion cycle in the ecosystem. Under the assumption that the ecosystem tends to minimize net proton production or consumption in order to keep the chemical soil state in optimal conditions for growth, the characteristic features of stable forest ecosystems showing high resilience are deduced. A sequence of ecosystem states is described; aggradation phase, stability range I (high resilience), destabilization phase I (humus disintegration), stability range II (low resilience), destabilization phase II (build up of decomposer refuge, podzolization). A continuous input of acidity exceeding the rate of base cation release by silicate weathering within the root zone forces forest ecosystems from the stability ranges into the transition states (destabilization phases). The concept of stress and strain is used to deduce how acid deposition superimposes natural stress factors and may trigger forest damages connected with climatical extremes and pests.

Regulation of Sucrose Synthesis by Cytoplasmic Fructosebisphosphatase and Sucrose Phosphate Synthase during Photosynthesis in Varying Light and Carbon Dioxide

Abstract: The aim of this work was to investigate whether sucrose synthesis in the cytosol of leaf cells is regulated in response to the supply of energy and organic carbon from the chloroplast. Fluxes into sucrose and metabolite levels in wheat (Triticum aestivum var Timmo) leaf protoplasts were compared in a range of light intensities and CO2 concentrations, showing that sucrose-phosphate synthase and the cytosolic fructose-1,6-bisphosphatase are inhibited in situ when the supply of trioseP from the chloroplasts decreases. Such a regulation might aid CO2 fixation in limiting conditions by permitting stromal metabolites to be maintained at higher levels than would otherwise be possible.

Secologanin, a Biogenetic Key Compound—Synthesis and Biogenesis of the Iridoid and Secoiridoid Glycosides

Abstract: The monoterpene glycoside secologanin is a key intermediate in the biosynthesis of most indole, cinchona, ipecacuanha, and pyrroloquinoline alkaloids, as well as of simple monoterpene alkaloids. More than a thousand alkaloids are formed from secologanin in vivo; this represents almost a quarter of this large group of natural products. It is also the parent compound of the secoiridoids. Many of the compounds derived from secologanin display a high degree of biological activity and are employed as pharmaceuticals, e.g., the dimeric indole alkaloid leurocristine (vincristine) which is used very successfully in the treatment of acute leukemia. A knowledge of the biosynthesis and biological reactions of secologanin provides a sound basis for the biosynthesis-orientated classification of numerous natural products and the taxonomy of many plants. Secologanin and structurally related substances can be synthesized in a few steps by stereocontrolled photochemical and thermal cycloadditions. Its biomimetic reaction with amines and amino acids yields other natural products and compounds of pharmacological interest.

Biokarst on Limestone Coasts, Morphogenesis and Sediment Production

Abstract: . Biokarst-forms on limestone coasts are developed and arranged according to the bionomic zonation. The development of biokarst is the result of bioerosion, a synergistic effect of biological corrosion by endoliths and biological abrasion by grazers. The cumulative effect of biogenic carbonate destruction leads to coastal destruction with a resulting highly profiled morphology on the limestone surfaces along the coastal profile. Under the influence of environmental factors a zonation of organisms develops which brings in turn a zonation of erosion rates (0.1-1.1 mm a-1) resulting in biokarst-forms such as rock holes, rock pools and notches. Products of bioerosion on limestone coasts are dissolved carbonate (by biological corrosion, 10–30% of the decomposed limestone) and particulate carbonate (by biological abrasion, 70–90% of the decomposed limestone) both of which contribute directly or indirectly to nearshore sedimentation. Size and shape of the bioerosional grains are determined by the boring pattern of the endoliths. The fine-grained sediments (maximum within the fraction 20–63 μm) contribute 3–25 % to the nearshore sediments. Drastic changes in the biological zonation (like the mass invasion of the sea urchin Paracentrotus lividus in the Northern Adriatic since 1972 which eliminated nearly the entire macrophyte zone) due to unknown factors or pollution can have a profound effect on the bioerosion rates, altering them by as much as a factor of ten.

Histology and histogenesis of two different types of inverted urothelial papillomas.

Abstract: Inverted papillomas are rare tumors of the lower urinary tract. Among 1829 reclassified tumors of the urinary bladder, renal pelves, ureters, and urethra, there were 40 (2.2%) inverted papillomas. The great majority of these were localized in the bladder. Because of distinctive histologic features and patterns of growth it is possible to differentiate between two basic types of inverted papillomas which were termed "trabecular" and "glandular." The trabecular type consists of widely branched, anastomosing cords of urothelial cells originating directly from the overlying transitional epithelium. The trabeculae are arranged horizontally or perpendicularly to the surface epithelium and occasionally exhibit peripheral palisading of the cells. The glandular type is characterized by multiple round to oval islands of proliferated urothelial cells together with pseudoglandular and true glandular structures which are often still connected with the surface urothelium. The gland-like structures are lined by stratified urothelium, the true glands by mucus secreting columnar epithelium. Sometimes glandular metaplasia of an intestinal type with goblet cell formation could be observed. Inverted papillomas of the trabecular type arise histogenetically from a proliferation of the basal cells of the urothelium. The glandular type develops apparently from a proliferative cystitis cystica and glandularis which, therefore, should be considered a potentially preneoplastic lesion. The predominant view of the biological behavior of inverted papillomas is that of a benign neoplastic lesion. Morphologic findings supplied some arguments in favor of a low grade malignant potential of these tumors. However, their malignant transformation seemed to be much lower than that of exophytic papillomas.

Preservation of incretin activity after removal of gastric inhibitory polypeptide (GIP) from rat gut extracts by immunoadsorption.

Abstract: The action of watery rat gut extracts on glucose-induced insulin release in anaesthetized rats was examined before and after removal of GIP by immunoadsorption. Infusions of GIP-containing rat gut extracts nearly doubled the insulin release induced by intravenous glucose (1g · kg−1 · h−1). Peak insulin secretion was 98±11 mU/l (mean±SEM) after intravenous glucose and increased to 178±16 mU/l following infusion of glucose plus gut extract (p<0.005). After injection of GIP antiserum in sufficient amounts to neutralize the GIP activity in the gut extract preparation, the additional insulin release due to the gut extract was reduced by only 30%. After complete removal of GIP from gut extracts by immunoabsorption, more than 50% of the incretin effect remained. These data suggest that the insulinotropic activity of rat gut extracts can only be partially related to GIP. The existence of additional insulinotropic gut factors which may also be released following oral glucose is postulated.

Collisional deactivation of vibrationally highly excited polyatomic molecules. III. Direct observations for substituted cycloheptatrienes

Abstract: Vibrationally highly excited ethyl‐cycloheptatriene (41 600 cm−1) and isopropyl‐cycloheptatriene (41 800 cm−1) molecules in the electronic ground state have been prepared by UV laser excitation inducing one‐photon absorption and subsequent internal conversion. Collisional energy loss of these molecules has been followed directly by hot UV absorption spectroscopy. Average energies transferred per collision 〈ΔE〉 have been determined for a series of bath gases. 〈ΔE〉 values were found, for a given bath gas, to increase very slightly with the size of the excited molecule.

Kinetics of the Reactions of OH-Radicals with Benzene, Benzene-d6 and Naphthalene

Abstract: Absolute rate constants for the reactions of hydroxyl radicals with benzene (1), benzene-d6 (2), and naphthalene (3) have been obtained using excimer laser photolysis to generate OH and time resolved resonance fluorescence as its monitor. Reaction (1) was studied at total pressures between 1.5 and 112 mbar at 298 K using Ar as a diluent gas. k1 is found to increase with pressure up to –40 mbar, but to be essentially pressure independent at still higher pressures, k (298 K) = (7.0 ± 1.5) 1011 cm3/mol · s. The temperature variation of k1 as studied over the range 244 – 24 K. At temperatures below 330 K normal Arrhenius behaviour with k1 (T) = (3.8 ± 1.0) 1012 exp[-(500 ± 50) K/T] cm3/mol · s is observed, corresponding to the addition reaction (1) OH + C6H6 C6H6OH. Between 330 and 420 K a sharp decrease of k1 with increasing temperature is noted, which we attribute to reaction (1) becoming reversible. For the stabilization energy of C6H6OH we derive (79 ± 6) kJ/mol. Above 420 K a transition of k1 to a positive temperature dependence, corresponding to the abstraction reaction (1') OH + C6H6 H2O + C6H5 is noted. Rate constants for the reaction of OH with benzene-d6 (2) are essentially identical to those of reaction (1) except for temperatures above 420 K, where k2 falls considerably below k1. This isotope effect is a confirmation of the (1') abstraction route. Reaction (3) was studied at total pressures between 6 and 128 mbar (He) where it is found to be essentially pressure independent. Its temperature variation was studied between 337 and 525 K. Over this region the rate coefficient decreases from (8.8 ± 3.5) 1012 cm3/mol · s to (6.6 ± 2.6) 1011 cm3/mol · s, with the decrease with temperature being relatively weak up to 410 K, k1(T ≤ 410 K) = (2.2 ± 1.0) 1012 exp[(440 ± 50) K/T] cm3/mol · s, and stronger at still higher temperatures. This behaviour is interpreted as to correspond to the addition reaction (3) OH + C10H8 C10H8OH and its equilibration. The stabilization energy of the OH-naphthalene adduct is estimated to be (95 ± 6) kJ/mol.

Microautoradiographic studies of phloem loading and transport in the leaf of Zea mays L.

Abstract: Microautoradiographs showed that [14C]sucrose taken up in the xylem of small and intermediate (longitudinal) vascular bundles of Zea mays leaf strips was quickly accumulated by vascular parenchyma cells abutting the vessels. The first sieve tubes to exhibit 14C-labeling during the [14C]sucrose experiments were thick-walled sieve tubes contiguous to the more heavily labeled vascular parenchyma cells. (These two cell types typically have numerous plasmodesmatal connections.) With increasing [14C]sucrose feeding periods, greater proportions of thick- and thin-walled sieve tubes became labeled, but few of the labeled thin-walled sieve tubes were associated with labeled companion cells. (Only the thin-walled sieve tubes are associated with companion cells.) When portions of leaf strips were exposed to 14CO2 for 5 min, the vascular parenchyma cells-regardless of their location in relation to the vessels or sieve tubes-were the most consistently labeled cells of small and intermediate bundles, and label (14C-photosynthate) appeared in a greater proportion of thin-walled sieve tubes than thick-walled sieve tubes. After a 5-min chase with 12CO2, the thin-walled sieve tubes were more heavily labeled than any other cell type of the leaf. After a 10-min chase with 12CO2, the thin-walled sieve tubes were even more heavily labeled. The companion cells generally were less heavily labeled than their associated thin-walled sieve tubes. Although all of the thick-walled sieve tubes were labeled in portions of leaf strips fed 14CO2 for 5 min and given a 10-min 12CO2 chase, only five of 72 vascular bundles below the 14CO2-exposed portions contained labeled thick-walled sieve tubes. Moreover, the few labeled thick-walledsieve tubes of the “transport region” always abutted 14C-labeled vascular parenchyma cells. The results of this study indicate that (1) the vascular parenchyma cells are able to retrieve at least sucrose from the vessels and transfer it to the thick-walled sieve tubes, (2) the thick-walled sieve tubes are not involved in long-distance transport, and (3) the thin-walled sieve tubes are capable themselves of accumulating sucrose and photosynthates from the apoplast, without the companion cells serving as intermediary cells.

Teleparallelism-A viable theory of gravity?

Abstract: The teleparallelism theory of gravity is presented as a constrained Poincar\'e gauge theory. Arguments are given in favor of a two-parameter family of field Lagrangians quadratic in torsion. The inclusion of a "parity violating" term in the field Lagrangian avoids difficulties with the initial-data problem, recently discussed in the literature. Several new exact solutions of the corresponding teleparallelism theory give considerable insight into its physical consequences. The resulting general field equations are analyzed in the weak-field approximation excluding ghosts and tachyons. The physical meaning of the six additional components of the tetrad field (as compared with the metric) appears naturally from our theory and is made clear.

Immunohistochemical and biochemical detection of uridine-diphosphate-glucuronyltransferase (UDP-GT) activity in putative preneoplastic liver foci

Abstract: Preneoplastic liver foci were produced in female Wistar rats by the administration of 2-acetylaminofluorene (0.03% w/w) in the diet for 174 days. Increased UDP-glucuronyltransferase (UDP-GT) could be visualized immunohistochemically in the same focal areas which were ATPase-negative andγ-glutamyltranspeptidase-positive. Immunohistochemical detection was possible using rabbit anti-UDP-GT and peroxi-dase-labeled swine anti-rabbit immunoglobulins. The results of immuno-histochemistry were substantiated by enzyme determination in micro-dissected material. UDP-GT activity was 5-fold higher in focal areas in comparison with the surrounding liver tissue.

Limit Theorems for Sums of Weakly Dependent Banach Space Valued Random Variables

Abstract: We prove an estimate for the Prohorov-distance in the central limit theorem for strong mixing Banach space valued random variables. Using a recent variant of an approximation theorem of Berkes and Philipp (1979) we obtain as a corollary a strong invariance principle for absolutely regular sequences with error term $$t^{\tfrac{1}{2} - \gamma }$$ . For strong mixing sequences we prove a strong invariance principle with error term o((t log logt)1/2).