Showing papers by "University of Konstanz published in 1984"
TL;DR: Growth yields were determined with Acetobacterium woodii strain NZva 16 on hydrogen and CO2, formate, methanol, vanillate, ferulate and fructose in mineral medium in the absence and presence of 0.05% yeast extract.
Abstract: Growth yields were determined with Acetobacterium woodii strain NZva 16 on hydrogen and CO2, formate, methanol, vanillate, ferulate and fructose in mineral medium in the absence and presence of 0.05% yeast extract. Yeast extract was not essential for growth but enhanced growth yields by 25–100% depending on the substrate fermented. Comparison of yields on formate or methanol allowed calculation of an energy yield in the range of 1.5–2 mol ATP per mol acetate formed during homoacetate fermentation of A. woodii. In the presence of 6 mM caffeate, growth yields were determined with the substrates formate or methanol. Caffeate was reduced to hydrocaffeate and increased growth yields were obtained. An ATP yield of about 1 mol per mol of caffeate reduced was calculated. Cytochromes were not detectable in cell free extracts or membrane preparations.
485 citations
243 citations
TL;DR: One of the main ideas of calculi of natural deduction, as introduced by Jaśkowski and Gentzen, is that assumptions may be discharged in the course of a derivation as well as not only formulas but also rules may serve as assumptions which can be discharged.
Abstract: One of the main ideas of calculi of natural deduction, as introduced by Jaśkowski and Gentzen, is that assumptions may be discharged in the course of a derivation. As regards sentential logic, this conception will be extended in so far as not only formulas but also rules may serve as assumptions which can be discharged. The resulting calculi and derivations with rules of any finite level are informally introduced in §1, while §§2 and 3 state formal definitions of the concepts involved and basic lemmata. Within this framework, a standard form for introduction and elimination rules for arbitrary n-ary sentential operators is motivated in §4, understood as a contribution to the theory of meaning for logical signs. §5 proves that the set {&, ∨, ⊃, ⋏} of standard intuitionistic connectives is complete, i.e. &, ∨, ⊃, and ⋏ suffice to express each n-ary sentential operator having rules of the standard form given in §4. §6 makes some remarks on related approaches. For an extension of the conception presented here to quantifier logic, see [11].
197 citations
TL;DR: Simple mechanical sieving provides a sufficient explanation for the mechanism of particle retention of the filtering process in Daphnia.
Abstract: Food size selection of four Daphnia, species (D. magna, D. hyalina, D. galeata, D. pulicaria) was investigated using spherical plastic beads as artificial food and with small bacteria. The size of the particles ranged from 0.1 to 35 μm with special emphasis to the particle diameters between 0.1 and 1 μm. In one set of experiments a mixture of differently sized particles was offered as food suspension and the selectivity of filtering was determined by comparing the size spectrum of the particles found in the gut contents with the spectrum in the food suspension. In a second series of experiments suspensions of uniformly sized particles were offered to single animals and their feeding activity was observed directly. In both types of experiments the mesh sizes of the filtering apparatus of the respective animals studied were measured after the experiments by, scanning electron microscopy. The mean sizes of the filter meshes were about 0.4–0.7 μm. In all experiments the size of the particles found in the gut or those which caused high feeding activities were larger than the smallest mesh sizes of the filters. As a consequence simple mechanical sieving provides a sufficient explanation for the mechanism of particle retention of the filtering process in Daphnia. D. magna was found to feed with high efficiency on suspended freshwater bacteria, the residual species investigated showed low filtering efficiencies when bacteria were offered as food.
193 citations
TL;DR: In this paper, the synthesis of new monomer building blocks for oligonucleotide synthesis via the phosphotriester approach containing the p -nitrophenylethyl group for phosphate and aglycone protection are described.
192 citations
TL;DR: It is concluded that ATP synthesis in P. modestum is driven by a Na+ ion gradient which is generated upon decarboxylation of methylmalonyl‐CoA, and that Na+ functions as the coupling ion.
Abstract: We report here a new mode of ATP synthesis in living cells The anaerobic bacterium Propionigenium modestum gains its total energy for growth from the conversion of succinate to propionate according to: succinate + H(2)O --> propionate + HCO(3) ( big up tri, openG' = -206 kJ/mol) The small free energy change of this reaction does not allow a substrate-linked phosphorylation mechanism, and no electron transport phosphorylation takes place Succinate was degraded by cell-free extracts to propionate and CO(2) via succinyl-CoA, methyl-malonyl-CoA and propionyl-CoA This pathway involves a membrane-bound methylmalonyl-CoA decarboxylase which couples the exergonic decarboxylation with a Na ion transport across the membrane The organism also contained a membrane-bound ATPase which was specifically activated by Na ions and catalyzed and transport of Na ions into inverted bacterial vesicles upon ATP hydrolysis The transport was abolished by monensin but not by the uncoupler carbonylcyanide-p-trifluoromethoxy phenylhydrazone Isolated membrane vesicles catalyzed the synthesis of ATP from ADP and inorganic phosphate when malonyl-CoA was decarboxylated and malonyl-CoA synthesis from acetyl-CoA when ATP was hydrolyzed These syntheses were sensitive to monensin which indicates that Na functions as the coupling ion We conclude from these results that ATP synthesis in P modestum is driven by a Na ion gradient which is generated upon decarboxylation of methylmalonyl-CoA
185 citations
TL;DR: The time courses of the various changes which are similar to those in chronic nerve stimulation experiments, indicate that various functional systems of the muscle fibre do not change simultaneously.
Abstract: Effects of a long-term, high intensity training program upon histochemically assessed myofibrillar actomyosin ATPase, myosin composition, peptide pattern of sarcoplasmic reticulum (SR), and parvalbumin content were analysed in muscles from the same rats which were used in a previous study (Green et al. 1983). Following 15 weeks of extreme training, an increase in type I and type IIA fibres and a decrease in type IIB fibres occurred both in plantaris and extensor digitorum longus (EDL) muscles. In the deep portion of vastus lateralis (VLD), there was a pronounced increase from 10±5% to 27±11% in type I fibres. No type I fibres were detected in the superficial portion of vastus lateralis (VLS) both in control and trained animals. An increase in slow type myosin light chains accompanied the histochemically observed fibre type transition in VLD. Changes in the peptide pattern of SR occurred both in VLS and VLD and suggested a complete transition from type IIB to IIA in VLS and from type IIA to I in VLD. A complete type IIA to I transition in the VLD was also suggested by the failure to detect parvalbumin in this muscle after 15 weeks of training. Changes in parvalbumin content and SR tended to precede the transitions in the myosin light chains. Obviously, high intensity endurance training is capable of transforming specific characteristics of muscle fibres beyond the commonly observed changes in the enzyme activity pattern of energy metabolism. The time courses of the various changes which are similar to those in chronic nerve stimulation experiments, indicate that various functional systems of the muscle fibre do not change simultaneously.
182 citations
TL;DR: In this paper, a direct synthesis of O-α-and O-β-Glycosyl-imidaten is presented, which can be isolated as stable compounds.
176 citations
TL;DR: In this paper, a base-catalyzed addition of 1-O-unsubstituted 2-azidohexoses to trichloroacetonitrile led to the corresponding O-glycosyl triacetimidates.
171 citations
TL;DR: After a 2-year drought period, the physiological sequence of reactivation is respiration—photosynthesis—nitrogen fixation, whereas recovery of nitrogen fixation is dependent on newly differentiated heterocysts.
Abstract: The response of the terrestrial blue-green algae Nostoc flagelliforme, Nostoc commune, and Nostoc spec. to water uptake has been investigated after a drought period of approximately 2 years. Rapid half-times of rewetting (0.6, 3.3, and 15.5 min, respectively) are found. The surfaceto-mass ratio of the three species is inversely correlated to the speed of water uptake and loss. The ecological relevance of these different time courses is discussed.Respiration starts immediately after a 30-min rewetting period, whereas photosynthetic oxygen evolution reaches its maximum activity after 6 and 8 h with N. commune and N. flagelliforme, respectively. In the dark, recovery of oxygen uptake by N. commune is somewhat impaired, while slightly stimulated with N. flagelliforme. With both species, recovery of photosynthesis is inhibited by darkness.Using colonies kept dry for two years, nitrogenase activity of N. commune attains its maximum 120 to 150 h after rewetting, while only 50 h were needed with algal mats kept dry for two days.Thus, after a 2-year drought period, the physiological sequence of reactivation is respiration-photosynthesis-nitrogen fixation. Respiration and photosynthesis precede growth and are exhibited by existing vegetative cells, whereas recovery of nitrogen fixation is dependent on newly differentiated heterocysts.
159 citations
TL;DR: Since both types of bacteria can not be affiliated to any of the existing genera and species, the new species Pelobacter carbinolicus and Pelobacteria propionicus are proposed.
Abstract: From anaerobic enrichments with 2,3-butanediol as sole substrate pure cultures of new Gram-negative, strictly anaerobic, non-sporeforming bacteria were isolated. Similar isolates were obtained with acetoin as substrate. From marine muds in saltwater medium a short rod (strain Gra Bd 1) was isolated which fermented butanediol, acetoin and ethylene glycol to acetate and ethanol. The DNA base ratio of this strain was 52.3 mol% guanine plus cytosine.
TL;DR: The well-known intensity anomalies in the mass spectra of water clusters evolve via evaporation of monomers as discussed by the authors, and the depletion of the relative unstable 22-mer and 29-mer occurs surprisingly late, in the time window 4 t
TL;DR: Four strains of new homoacetogenic bacteria were enriched and isolated from freshwater sediments and sludge with ethanol, propanol, 1,2-propanediol, or 1, 2-butanediol as substrates and methane was formed in coculture with methanogens, probably due to interspecies hydrogen transfer.
Abstract: Four strains of new homoacetogenic bacteria were enriched and isolated from freshwater sediments and sludge with ethanol, propanol, 1,2-propanediol, or 1,2-butanediol as substrates. All strains were Gram-positive nonsporeforming rods and grew well in carbonate-buffered defined media under obligately anaerobic conditions. Optimal growth occurred at 27° C around pH 7.0. H2/CO2, primary aliphatic alcohols C3−C5, glucose, fructose, lactate, pyruvate, ethylene glycol, 1,2-propanediol, 2,3-butanediol, acetoin, glycerol, and methyl groups of methoxylated benzoate derivates and betaine were fermented to acetate or, in case of primary alcohols C3−C5 and 1,2-propanediol, to acetate and the respective fatty acid. In coculture with methanogens methane was formed, probably due to interspecies hydrogen transfer. Strain WoProp 1 is described as a new species, Acetobacterium carbinolicum. It had a DNA base composition of 38.5±1.0% guanine plus cytosine, and contained murein of crosslinkage type B similar to A. woodii.
TL;DR: The resistance of nitrogenase towards oxygen inactivation decreased after transfer of autotrophically grown cells into the dark at subsequent stages of increasing culture density and the inactivation was prevented by addition of fructose.
Abstract: Nitrogenase (=acetylene-reducing activity) was followed during photoautotrophic growth of Anabaena variabilis (ATCC 29413). When cell density increased during growth, (1) inhibition of light-dependent activity by DCMU, an inhibitor of photosynthesis, increased, and (2) nitrogenase activity in the dark decreased. Addition of fructose stabilized dark activity and alleviated the DCMU effect in cultures of high cell density.
TL;DR: The permeability properties of the outer membrane of the chloroplast envelope were studied and the exclusion limit for the penetration of molecules through this membrane into the intermembrane space lies between M r values of about 7000–13 000, which is the largest exclusion limit measured so far for pores of the porin type.
TL;DR: The results suggest that the burst kinetic and the kinetic within bursts are regulated by independent voltage sensitive mechanisms.
Abstract: Using the patch-clamp technique single-channel parameters and kinetic properties of an anionic channel are studied in cell-attached and exised membrane patches from peritonal macrophages of mouse and cultured chicken myotubes. The channel has a unit conductance of about 340 pS with a Q10 of 1.3. In addition a subconductance state of about 210 pS in frequently adopted. The selectivity ratio of PCl/PNa is about 5. In excised membrane patches the activation of the channel appears to be independent of Ca either in the cytoplasmic or the extracellular medium. The channel induced current fluctuations appear in a burst like pattern. At least three non-conducting channel states could be distinguished kinetically. The mean lifetime of one of these states exhibits a strikingly steep voltage dependence which could be correlated to the mean shut interval between consecutive bursts. A similar steep voltage dependence was found for the mean liefetimes of bursts. The burst kinetic shows an about bell-shaped dependence on voltage. The results suggest that the burst kinetic and the kinetic within bursts are regulated by independent voltage sensitive mechanisms. The burst kinetic was analyzed by ensemble averages of voltage-jump current relaxations performed on the single channel level. A model of two voltage-sensitive gates is proposed for a description of the burst kinetic.
TL;DR: The measurements showed a large scatter of the two enzyme activities in these two myosin-based fibre types, whereas generally IIA fibres have higher SDH activities than IIB fibres, both in rabbit and in mouse.
Abstract: Quantitative microphotometric measurements of two mitochondrial flavoproteins, glycerolphosphate oxidase (GP-OX) and succinate dehydrogenase (SDH), were performed on serial sections of mouse and rabbit tibialis anterior (TA) muscles in order to study the distribution of these two enzymes and their activity ratios in IIA and IIB fibres. The measurements showed a large scatter of the two enzyme activities in these two myosin-based fibre types. In rabbit TA, IIA and IIB fibres have similar GP-OX activities, whereas generally IIA fibres have higher SDH activities than IIB fibres. An inverse distribution of the two enzymes exists in mouse muscle. Generally, IIA fibres of mouse TA display low SDH and IIB fibres high SDH activities. The mean activity of GP-OX is slightly higher in IIA than in IIB fibres of mouse TA. Since measurements of both enzymes were taken in the same fibres, the ratio of their activities in each fibre could be evaluated. The SDH/ GP-OX activity ratios vary significantly between the two fibre populations both in rabbit and in mouse. The ratio is high in IIA and low in IIB fibres of rabbit TA, whereas it is low in IIA and high in IIB fibres of mouse TA.
TL;DR: The distribution of the afferents to the rat's prefrontal cortex originating in the thalamic mediodorsal nucleus and the amygdala was investigated with two fluorescent tracers, with special emphasis on detecting the loci of neurons which project via axonal collaterals into both lateral and medial portions of the prefrontal cortex.
Abstract: The distribution of the afferents to the rat's prefrontal cortex originating in the thalamic mediodorsal nucleus and the amygdala was investigated with two fluorescent tracers. Special emphasis was laid on detecting the loci of neurons which project via axonal collaterals into both lateral and medial portions of the prefrontal cortex. It was found that a high number of neurons of the anterior portion of the basolateral amygdaloid nucleus terminate via collaterals in both the medial and lateral subfields of the prefrontal cortex. On the other hand, only a small number of mediodorsal thalamic cells were found to project to both sides of the prefrontal hemisphere via bifurcating axonal collaterals. These cells were situated exclusively in the lateral part of the medial segment of the mediodorsal nucleus. The majority of both thalamic and amygdaloid neurons with bifurcating axons originate from subregions whose cells innervate primarily the medial prefrontal cortex. In brain-stem, neurons of the nucleus raphe dorsalis also project via collaterals to the medial and lateral prefrontal regions. Furthermore, neurons of the dorsal and ventral premamillary nuclei, the lateral mamillary nucleus, the ventral tegmental area of Tsai, and the ventral tegmental nucleus of Gudden were found to project to the medial prefrontal cortex. Our results indicate a differential collateral organization of thalamic and amygdaloid afferents to prefrontal cortical fields. The anterior basolateral amygdala (which innervates via collaterals both the medial and lateral prefrontal subfields) may add a common input to either subfield, such as information on the significance of incoming stimuli to the animal's behavior, while the mediodorsal nucleus (whose segments are principally connected to only one prefrontal subfield) may add segment-specific information, for example, of a spatial-cognitive nature for the lateral segment and of an emotional nature for the central and medial segments. The existence of a basolateral limbic circuit, composed of the amygdala, the thalamic mediodorsal nucleus, and the prefrontal cortex, is confirmed and knowledge on its interconnectivity is extended. From an anatomical point of view these data provide arguments for both unitary and diverging functions of the prefrontal cortex.
TL;DR: In this article, the authors showed that the reactivity differences of 2α,β and the stability differences of 3-α/β are due to lone pair repulsions implicated in the anomeric effect.
TL;DR: Authorities on road traffic accidents should consider an additional perceptual time of at least 300 milliseconds for detecting critical changes in headway beyond the usual reaction time, as an alteration of the conception of safe intervehicle distances in a convoy.
Abstract: When one is riding in a vehicle, perceptual thresholds for motion of objects are significantly elevated above those determined under corresponding but simulated conditions in the laboratory without concurrent self-motion perception. Authorities on road traffic accidents should thus consider an additional perceptual time of at least 300 milliseconds for detecting critical changes in headway beyond the usual reaction time. Detection times thus corrected consequently lead to an alteration of our conception of safe intervehicle distances in a convoy. This elevation of thresholds for object-motion during self-motion, with its consequences for visual control of vehicle guidance, can be seen as a disadvantageous side effect of an otherwise beneficial space-constancy mechanism, which provides us with a stable world during locomotion.
TL;DR: This chapter discusses the results of the work on exocytosis in Paramecium as well as the implications of these results for exocyTosis in general.
TL;DR: In this article, it is shown that more than 60% of the cell carbon is derived from CO2 and the rest from formate and that CO2 fixation does not proceed via the Calvin cycle, and the capacity to synthesize an acetate unit from two C1-compounds obviously distinguishes D. baarsii from those Desulfovibrio species which require acetate as a carbon source in addition to CO2.
Abstract: Desulfovibrio baarsii is a sulfate reducing bacterium, which can grown on formate plus sulfate as sole energy source and formate and CO2 as sole carbon sources. It is shown by 14C labelling studies that more than 60% of the cell carbon is derived from CO2 and the rest from formate. The cells thus grow autotrophically. Labelling studies with [14C]acetate, 14CO and [14C]formate indicate that CO2 fixation does not proceed via the Calvin cycle. The labelling patterns of alanine, aspartate, glutamate, and glucosamine indicate that acetate (or activated acetic acid) is an early intermediate in formate and CO2 assimilation; the methyl group of acetate is derived from formate, and the carboxyl group from CO2 via CO; pyruvate is formed from acetyl-CoA by reductive carboxylation. The capacity to synthesize an acetate unit from two C1-compounds obviously distinguishes D. baarsii from those Desulfovibrio species, which require acetate as a carbon source in addition to CO2.
TL;DR: In this paper, it was shown by molecular dynamics simulation that the formation of a molecular dimer ion within an ionized rare-gas cluster will produce several evaporations, thus destroying any magic numbers of the neutral clusters.
TL;DR: The claustral projections to the cat's limbic cortex were investigated with horseradish peroxidase retrograde tracing technique and with autoradiography and revealed that the distribution of claustro-cortical afferents is uneven and that the ventral claustrum sends fibers to more cortical regions than previously assumed.
TL;DR: It is found that triggering of trichocyst release by AED involves a local, non-propagated effect and that all regions of the cell body are equally reactive.
TL;DR: A new mesophilic, sporeforming, strictly anaerboic bacterium was isolated form enrichments with 2,3-butanediol as sole substrate and pasteurized freshwater sediment as inoculum and was described as a new species, Clostridium magnum sp.
Abstract: A new mesophilic, sporeforming, strictly anaerboic bacterium was isolated form enrichments with 2,3-butanediol as sole substrate and pasteurized freshwater sediment as inoculum. Cells were large, motile rods, and elliptical spores were formed subterminally or centrally. They stained Gram-negative, but no typical outer membrane layer could be observed by electron microscopy of ultrathin sections. 2,3-Butanediol, acetoin, fructose, glucose, sucrose, xylose, malate and citrate served as substrates and were completely converted to acetate with concomitant reduction of carbon dioxide. Growth on glucose (tdmin=1.4 h) was faster than on butanediol (tdmin=3.6 h). No growth occurred on hydrogen/carbon dioxide, on formate or on methanol. The guanine plus cytosine content of the DNA was 29.1%. The new isolate is described as a new species, Clostridium magnum sp. nov.
TL;DR: Deoxynucleoside methylphosphonamidites have been synthesized as building monomers for the stepwise synthesis of methyl phosphonate analogs of oligonucleotides as mentioned in this paper.
TL;DR: From marine anoxic mud, a new strictly anaerobic, Gram-negative, non-sporeforming bacterium was isolated with 3-hydroxybutyrate as substrate and type strain CuHbu1 is described as type strain of a new genus and species, Ilyobacter polytropus gen. sp.
Abstract: From marine anoxic mud, a new strictly anaerobic, Gram-negative, non-sporeforming bacterium was isolated with 3-hydroxybutyrate as substrate 3-Hydroxybutyrate and crotonate were fermented to acetate and butyrate Glycerol was fermented to 1,3-propanediol and 3-hydroxypropionate Acetate and formate were the only products of pyruvate or citrate fermentation Glucose and fructose were fermented to acetate, formate and ethanol Malate and fumarate were fermented to acetate, formate and propionate Neither sulfate, sulfur, nor nitrate was reduced The DNA base ratio was 322±05 mol% guanine plus cytosine Strain CuHbu1 is described as type strain of a new genus and species, Ilyobacter polytropus gen nov sp nov, in the family Bacteroidaceae