Showing papers by "University of Konstanz published in 1982"

Studies on dissimilatory sulfate-reducing bacteria that decompose fatty acids II. Incomplete oxidation of propionate by Desulfobulbus propionicus gen. nov., sp. nov.

Abstract: A new type of sulfate-reducing bacteria with ellipsoidal to lemon-shaped cells was regularly enriched from anaerobic freshwater and marine mud samples when mineral media with propionate and sulfate were used. Three strains (1pr3, 2pr4, 3pr10) were isolated in pure culture. Propionate, lactate and alcohols were used as electron donors and carbon sources. Growth on H2 required acetate as a carbon source in the presence of CO2. Stoichiometric measurements revealed that oxidation of propionate was incomplete and led to acetate as an endproduct. Instead of sulfate, strain 1pr3 was shown to reduce sulfite and thiosulfate to H2S; nitrate also served as electron acceptor and was reduced to ammonia. With lactate or pyruvate, all three strains were able to grow without external electron acceptor and formed propionate and acetate as fermentation products. None of the strains contained desulfoviridin. In strain 1pr3 cytochromes of the b- and c-type were identified. Strain 1pr3 is described as type strain of the new species and genus, Desulfobulbus propionicus.

A Comparative Microphotometric Study of Succinate Dehydrogenase Activity Levels in Type I, IIA and IIB Fibres of Mammalian and Human Muscles

Abstract: Activity levels of succinate dehydrogenase (SDH) were determined kinetically by means of comparative microphotometric measurements in situ. Activities were correlated with fibre types classified histochemically according to Brooke and Kaiser (1970). Analyses of tibialis anterior muscles in the mouse, rat, guinea pig, rabbit, cat and the human showed pronounced variations in the activity profiles of type I, type IIA and IIB fibres of these muscles. Large scattering of enzyme activity existed in the three fibre populations. Overlaps of varying extent were found for the SDH profiles between the different muscles. Type I fibres reveal species diffeences in aerobic oxidative capacity. Whereas the majority of the IIB fibres in rabbit muscle tended to be low in SDH activity, the main fraction of this fibre population was characterized by high activities in mouse muscle. Similarly, the IIA fibre populations revealed opposite properties in mouse and rabbit muscles. These extremes as well as intermediate activity patterns indicate that no general scheme exists according to which the histochemically assessable myosin ATPase is correlated with the aerobic oxidative capacity of muscle fibres in various mammalian muscles.

Cryofixation : A Tool In Biological Ultrastructural Research

Abstract: Publisher Summary This chapter describes the technique for cryofixation. The goal of ultrastructural fixation methods is to preserve the momentary distribution of all components in a system. For molecular systems, this implies the maintenance of the statistical distribution of all solute components in the solvent and the preservation of the size and shape of the macromolecules in the hydrated state. Cryofixation and freeze-storage of biological materials are important problems in many regards: for the storage of living materials, for the storage and processing of proteins, and for the preservation of structural details. The main problem of cryofixation is that the “fixed” structures are thermodynamically unstable at low temperatures. It is important to have several different cryofixation techniques at hand, if the variety of biological materials and the broad spectrum of secondary techniques are considered, whereby each has its requirements.

Fermentation of Trihydroxybenzenes by Pelobacter acidigallici gen. nov. sp. nov., a New Strictly Anaerobic, Non-Sporeforming Bacterium

Abstract: Five strains of rod-shaped, Gram-negative, non-sporing, strictly anaerobic bacteria were isolated from limnic and marine mud samples with gallic acid or phloroglucinol as sole substrate. All strains grew in defined mineral media without any growth factors; marine isolates required salt concentrations higher than 1% for growth, two freshwater strains only thrived in freshwater medium. Gallic acid, pyrogallol, 2,4,6-trihydroxybenzoic acid, and phloroglucinol were the only substrates utilized and were fermented stoichiometrically to 3 mol acetate (and 1 mol CO2) per mol with a growth yield of 10g cell dry weight per mol of substrate. Neither sulfate, sulfur, nor nitrate were reduced. The DNA base ratio was 51.8% guanine plus cytosine. A marine isolate, Ma Gal 2, is described as type strain of a new genus and species, Pelobacter acidigallici gen. nov. sp. nov., in the family Bacteroidaceae. In coculture with Acetobacterium woodii, the new isolates converted also syringic acid completely to acetate. Cocultures with Methanosarcina barkeri converted the respective substrates completely to methane and carbon dioxide.

Signal processing times in bacterial chemotaxis.

Abstract: The bacterium Escherichia coli responds to changes in the concentrations of various chemicals in its environment1. A cell swims along a smooth trajectory (runs), moves erratically for a brief time (tumbles) and then runs again, choosing a new direction at random2. If a run happens to carry the cell up a gradient of an attractant (such as aspartate, serine and certain sugars), the occupancy of the appropriate chemoreceptor increases with time3,4 and a signal is sent to the flagellar motors that increases their counterclockwise bias5. On the average, this extends favourable runs and the cell moves up the gradient. The receptors for aspartate and serine6–8 are proteins found in the cytoplasmic membrane, known as methyl-accepting chemotaxis proteins9,10, and are the products of the tar and tsr genes11. A cell can adapt to sustained changes of receptor occupancy by carboxymethylating these proteins12; it is not known, however, how these proteins signal the flagellar motors or how the signal controls the direction of flagellar rotation. Products of several che genes involved in signalling and adaptation have been identified13,14, but with the exception of a methyltransferase15 (the cheR product) and a demethylase16 (the cheB product), their functions are largely unknown. In an attempt to learn more about the events that trigger a chemotactic response, we have now exposed cells to rapid changes in the concentration of attractants and repellents and measured the time required for flagellar reversal. In wild-type cells and in cells containing a cheR–cheB deletion, the response latency is ∼0.2 s. In cheZ mutants, it is much longer.

Connections of the hippocampal formation, mamillary bodies, anterior thalamus and cingulate cortex. A retrograde study using horseradish peroxidase in the cat

Abstract: The afferent projections to, and the interconnections between, four structures of the so-called limbic system were investigated in the cat. The retrograde horseradish peroxidase (HRP) technique was used to trace the origins of fibers projecting to each of these four loci. Particular emphasis was laid on tracing cortical afferents of these regions. Four injections were performed in the dorsal and two in the ventral subicular regions; six were centered within the mamillary nuclei, four within the anterior thalamic nuclei, and three within the cingulate gyrus. For each region, a number of projections were found which had apparently not been described before, at least not for the cat: For injections into the subicular regions, a hitherto unknown number of cortical afferents was detected, including labeled cells in the prefrontal and premotor fields and from large areas within the posterior parietal, temporal and occipital cortex (i.e., sensory and sensory integration cortex); numerous neurons were labeled in the anterior nuclear group of the thalamus. Injections of HRP into the mamillary nuclei revealed, aside from a strong projection from the subicular regions, frontocortical and cingulate projections to the mamillary nuclei; the mamillary nuclei also received subcortical projections from the septum, the diagonal band of Broca and from the periaqueductal gray. Following injections into the anterior thalamic nuclei, labeled cells were found in the prefrontal cortex, and to a lesser extent in lateral parts of the cortical hemisphere; subcortically, the mamillary nuclei received connections from hypothalamic areas, the periaqueductal gray, the diagonal band of Broca and the claustrum. Cingulate injections labeled cells in temporal and parietal cortical areas, in the subicular region, and also in the periaqueductal gray. Our findings reveal that each of the four injected areas receives a large number of afferents from divergent regions of the brain; of these, a considerable number is shared by each of the four injection loci. Furthermore, the present results reveal that the subiculum, the mamillary bodies, and the anterior thalamus are more strongly interconnected than previously assumed.

Propionigenium modestum gen. nov. sp. nov. a new strictly anaerobic, nonsporing bacterium growing on succinate

Abstract: From marine and freshwater mud samples and from human saliva new strictly anaerobic, Gram-negative, nonsporeforming bacteria were isolated growing with succinate as sole source of carbon and energy. All strains grew in defined mineral media containing at least 1% sodium chloride. Succinate was stoichiometrically transformed to propionate und carbon dioxide; the growth yield varied between 2.1 and 2.4 g cell dry weight per mol of succinate fermented. In addition to succinate, only fumarate, l-aspartate, l-malate, oxaloacetate and pyruvate, were utilized and were stoichiometrically fermented to propionate and acetate. Yeast extract was not fermented but enhanced growth rates and yields. Neither sulfate, sulfur, nor nitrate were reduced. The DNA base ratio was 33.9±0.3 mol % guanine plus cytosine. A marine isolate, strain Gra Succ 2, is described as type strain of a new species, Propionigenium modestum gen. nov. sp. nov., in the family Bacteroidaceae.

Ultrasound recognition in house mice: key-stimulus configuration and recognition mechanism

Abstract: 1. We determined the ability of lactating female house mice (Mus musculus, strain NMRI) to recognize natural ultrasonic calls (USC) of their pups or synthesized USC models. Recognition was shown by the mice preferentially responding to these sounds in the presence of an alternative sound signal. 2. Preferred USC models had total durations (flat top + rise and fall times) between 30 and 270 ms. Shorter and longer ones were not preferentially responded to. Response to USC models with major frequency components above 40 kHz was the same as that to natural ultrasonic calls of mouse pups. 3. The key-stimulus configuration for recognition of mouse pup ultrasound in the frequency domain can be characterized as pulses of sound energy in a narrow frequency band in the ultrasonic range with significantly less energy in adjacent frequency bands. The decisive units for call recognition are frequency bandwidths which are almost identical in width with the critical bands of hearing, a measure of frequency resolution in the auditory system. The critical frequency bands for the recognition of USC models have a bandwidth of 22.5 kHz at a center frequency near 50 kHz (the critical band of hearing is 22 kHz wide), and 15 kHz at a center frequency near 40 kHz (the critical band of hearing is 18 kHz wide). We conclude that the discrimination of ultrasonic mouse pup calls from other mouse calls and their recognition is most probably directly related to the critical band analysis in the auditory system.

Identification of the glpT-encoded sn-glycerol-3-phosphate permease of Escherichia coli, an oligomeric integral membrane protein.

Abstract: A collection of hybrid plasmids carrying either the wild-type or mutated glpT gene was generated in vitro and used to characterize the glpT-dependent active transport system for sn-glycerol-3-phosphate in Escherichia coli K-12. Restriction endonuclease analysis and recloning of DNA fragments localized glpT to a 3-kilobase pair PstI-HpaI segment of DNA. Comparison of DNA carrying glpT-lacZ fusions with DNA carrying intact glpT allowed determination of the direction of transcription. Through characterization of the proteins synthesized by strains harboring hybrid plasmids carrying amber, missense, or deletion mutations in glpT, it was shown that glpT is a promoter-proximal gene in an operon consisting of at least two genes. The gene product of glpT, the sn-glycerol-3-phosphate permease, was found associated with the inner membrane. It could be solubilized by treatment with sodium dodecyl sulfate at 50 degrees C. Its molecular weight, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was dependent upon sample treatment before electrophoresis. The apparent molecular weight was 44,000 when membrane fractions were heated to 50 degrees C; subsequent treatment at 95 degrees C modified the protein such that it migrated faster (apparent molecular weight = 33,000). Several missense mutations in glpT were negatively dominant over wild-type glpT, indicating that the active form of the permease is multimeric. A gene (named glpQ) promoter distal to glpT codes for a periplasmic protein. This protein had previously been named GLPT protein to indicate its relationship to the glpT gene. The present report demonstrates that it is not the gene product of glpT and is not required for active transport of sn-glycerol-3-phosphate.

Self-diffusion of spherical Brownian particles with hard-core interaction

Abstract: The N -particle Smoluchowski equation is solved exactly for a system of spherical Brownian particles interacting through hard-core potentials to first order in the volume concentration φ. The self-diffusion coefficient is found to be given by D s = D 0 (1−2 φ ), where D 0 is the free diffusion constant. The hydrodynamic interaction is then taken into account in a perturbative way. Using the Oseen approximation, D s = D 0 (1−0.09 φ ) is found, whereas the improved form for the hydrodynamic interaction due to Felderhof gives D s = D 0 (1−1.89 φ ).

A comparison of two ATPase based schemes for histochemical muscle fibre typing in various mammals.

Abstract: A comparative study was performed on the fibre populations in tibialis anterior muscles of mouse, rat, guinea pig, rabbit, cat and dog using the two different methods of histochemical staining for myofibrillar ATPase after acid (Brooke and Kaiser 1970) or alkaline preincubations (Guth and Samaha 1970). For all species a complete correspondence existed between type I (Brooke and Kaiser 1970) and beta fibres (Samaha et al. 1970). Gross correspondence (greater than 85%) existed between IIA and IIB (Brooke and Kaiser 1970) and alpha beta and alpha fibres (Samaha et al. 1970) respectively in mouse, guinea pig, rabbit, cat and dog. In the case of mouse and dog, this high degree of correspondence was based on the assumption that mouse tibialis anterior contains no type I and the dog no type IIB fibres. For the rat, a pronounced overlap existed between IIA fibres on the one hand and alpha beta and alpha fibres on the other hand as well as between IIB fibres and alpha beta and alpha fibres. These observations lead to the conclusion that the two classification schemes are not interchangeable for all species and that the two terminologies should be used only in relation with the methods from which they were derived.

The effect of different patterns of long-term stimulation on contractile properties and myosin light chains in rabbit fast muscles.

Abstract: Fast rabbit skeletal muscles (tibialis anterior and extensor digitorum longus) were stimulated for 2–28 days by electrodes implanted in the vicinity of the peroneal nerve to produce maximal contractions at two different frequency patterns: that occuring naturally in nerves to slow muscles (10 Hz continuously) or three bursts of tetani (40 Hz) per minute, each 5s in duration. Both types of frequency produced muscles more resistant to fatigue during isometric twitch contractions, and led to a prolongation of contraction time greater and more consistent with 10 Hz than with 40 Hz. The twitch/tetanus ration was significantly higher in muscles stimulated at 10 Hz for 3–4 weeks but was not different from controls in muscles stimulated at 40 Hz. Both types of stimulation led to the appearance of myosin light chains characteristic of slow muscles. Muscles stimulated for 4 weeks at 40 Hz developed greater twitch tension per gram, and had significantly smaller cross-sectional area of myofibrils than control muscles. It is concluded that long-term electrical stimulation of fast muscles can affect some muscle contractile properties to resemble those of slow muscles irrespective of frequency of stimulation, provided the total number of stimuli is comparable, the duration of stimulation is long enough (minimum 2 weeks) and all motor units are activated.

The bacteria of the sulphur cycle

Abstract: This paper concentrates on the bacteria involved in the reductions and oxidations of inorganic sulphur compounds under anaerobic conditions. The genera of the dissimilatory sulphate-reducing bacteria known today are discussed with respect to their different capacities to decompose and oxidize various products of fermentative degradations of organic matter. The utilization of molecular hydrogen and formate by sulphate reducers shifts fermentations towards the energetically more favourable formation of acetate. Since acetate amounts to about two-thirds of the degradation products of organic matter, the complete anaerobic oxidation of acetate by several genera of the sulphate-reducing bacteria is an important function for terminal oxidation in sulphate-sufficient environments. The results of pure culture studies agree well with ecological investigations of several authors who showed the significance of sulphate reduction for the complete oxidation of organic matter in anaerobic marine habitats. In the dissimilatory sulphur-reducing bacteria of the genus Desulfuromonas the oxidation of acetate is linked to the reduction of elemental sulphur. Major characteristics of the anaerobic, sulphide-oxidizing phototrophic green and purple sulphur bacteria as well as of some facultative anoxygenic cyanobacteria, are given. By the formation of elemental sulphur and sulphate, these bacteria establish sulphur cycles with the sulphide-forming bacteria. In view of the morphological diversity of the sulphate-reducing bacteria and question of possible evolutionary relations to phototrophic sulphur bacteria is raised.

Pitfalls in the use of the torsion angle driving method for the calculation of conformational interconversions

Abstract: Several deficiencies and potential sources of error in the torsion angle driving method, the approach employed most frequently for the simulation of conformational interconversions, have been studied. A general explanation of the observed effects is given in terms of the energy surface and of the effects brought about by “side valleys.” Several examples of molecular mechanics calculations of conformational interconversions, among them the cyclohexane ring inversion, illustrate the problems.

Magic Numbers in Mass Spectra of Xe, C2F4Cl2 and SF6 Clusters

Abstract: Mass spectra of xenon clusters show pronounced intensity maxima for cluster sizes n* = 13, 19, 25, 55, 71, 87, and 147. The occurrence of these “magic numbers” is explained by shell closure of clusters growing in the icosahedral structure. Magic numbers in mass spectra of 1,2-dichlorotetra-fluoroethane are n* = 13 and 19. The only intensity maximum of sulfurhexafluoride clusters occurs at n* = 13, whereas a minimum is observed at n* = 18. In contrast, the size distributions of clusters of 17 other molecular gases decrease strictly monotonically with increasing size. The origin of these effects is discussed.

Quantitative differences in the currents of bursting and beating molluscan pace-maker neurones

Abstract: 1. The spontaneous activity and the membrane conductances to Na(+), Ca(2+) and K(+) ions of the bursting pace-maker neurone R-15 and the repetitively discharging (beating) pace-maker neurone L-11 in the abdominal ganglion of the marine mollusc, Aplysia californica, were compared.2. The bursting pace-maker R-15 can be converted to a beating pace-maker neurone by the removal of external Ca(2+) or by the injection of EGTA intracellularly. Bursting pace-maker activity is not restored by changes in the resting potential.3. Spontaneous action potentials of cell R-15 are reduced, but not abolished, by the addition of tetrodotoxin (TTX) to block Na(+) currents or by the removal of external Ca(2+) to abolish Ca(2+) currents, whereas the spontaneous action potentials of cell L-11 are abolished by external TTX, but are unaffected by external Ca(2+) removal.4. The membranes of both cells contain Na(+) and Ca(2+) inward currents. The specific Na(+) conductance of both cells is of similar magnitude, whereas the specific Ca(2+) conductance is about half the Na(+) conductance in R-15 cells and an order of magnitude smaller in L-11 cells.5. The delayed K(+) conductance of cell L-11 is about 1.2 times greater than this conductance in cell R-15. The transient K(+) currents of the two cells are about the same magnitude.6. The Ca(2+)-activated K(+) conductance of cell R-15 and cell L-11 was estimated using two methods. The Ca(2+)-activated K(+) conductance of cell R-15 estimated from the difference in the total outward current in normal external solution and the delayed K(+) current in Ca(2+)-free solution (to preclude Ca(2+) influx) or after internal EGTA injection (to prevent Ca(2+) accumulation) is about 23 times greater than this conductance in cell L-11. The Ca(2+)-activated K(+) conductance of cell R-15, estimated from local internal Ca(2+) injections in Ca(2+)-free solution, is about 3 times greater than this conductance in cell L-11.7. The leakage conductance of cell L-11 is about 1.3 times greater than this conductance in cell R-15. This conductance increases by a factor of about 2 in both cells in Ca(2+)-free external solutions containing 1 mM-EGTA, but is unchanged or is decreased slightly by injection of EGTA internally.8. It is concluded that the Ca(2+) conductance and the Ca(2+)-activated K(+) conductance are appreciably greater in the bursting pace-maker neurone R-15 than in the beating pace-maker neurone L-11, whereas other voltage-dependent conductances to Na(+) and K(+) ions as well as the leakage conductance are quite similar. These quantitative differences provide a basis for understanding the different spontaneous activities of the two cells.

Dynamics of colloidal crystals and colloidal liquids

Abstract: The dynamics of strongly interacting colloidal particles is studied in the range of medium to high particle concentrations. Both the short-range ordered liquid phase and the long-term ordered crystal phase are investigated by means of photon correlation spectroscopy. The results are discussed in terms of a memory function formalism which is shown to be applicable for both the liquids and the crystals. The viscoelastic approximation for the memory function describes the experimental results in the liquid phase very well. For the first time results on single crystals are reported which exhibit a purely elastic behaviour. The theory enables the authors to extract information on the elastic moduli and sound velocities of the systems from the data, which in principle yield information on the particle interaction potential. The 'phonon' dispersion of colloidal crystals is also presented.

Antibodies to Z-DNA interact with form V DNA

Abstract: Annealing of single-stranded (ss) DNA rings of complementary base sequence gives rise to the so-called form V DNA which is characterized by a linking number of zero1. The similarity of the circular dichroism spectrum of form V DNA1 with that of the 1:1 mixture of the low salt (B-type) and the high salt (Z-type) form of poly(dG-dC) ⋅ poly(dG-dC)2,3 suggests that form V DNA might contain left-handed double-helical DNA of the Z-type. The discovery that the left-handed Z-form of poly(dG-dC) ṁ poly(dG-dC) induces a strong immune response4,5 has provided a novel means of searching for DNA of this particular conformation6. We therefore used antisera and monoclonal antibodies to Z-DNA to determine whether form V DNA contains stretches of left-handed double-helical conformation. We report here that form V DNA competes in the binding of antibodies to Z-form poly(dG-dC) · poly(dG-dC). The competition by form V DNA is similar to that of (dG-dC)5·(dG-dC)5. Thus, DNA of natural base sequence, when forced to adopt left-handed conformations by topological restrictions, is recognized by antibodies against Z-DNA

The innervation pattern of crustacean skeletal muscle. Morphometry and ultrastructure of terminals and synapses.

Abstract: The innervation pattern of distal muscle fibers of the opener muscle of walking legs of crayfish (Astacus leptodactylus) was investigated using methylene-blue staining, cobalt infiltration, and electron microscopy. A quantitative analysis of the entire innervation of single muscle fibers was attempted.

O-Alkylierung am anomeren Zentrum, 4. 1-O-Alkylierung von D-Mannofuranose und D-Mannopyranose

Abstract: Aus 1-O-metallierter 2,3: 5,6-Di-O-isopropyliden-D-mannose (1) wurden mit starken Alkylierungsmitteln (Triflaten) β-D-Mannofuranoside, in Anwesenheit von Kronenether α-D-Mannofuranoside erhalten. Mit der 6-O-ungeschutzten D-Mannose 7 wurde durch Temperaturvariation eine entsprechende Lenkung der Stereoselektivitat zu α- oder β-Mannopyranosiden erzielt. Die bequeme Bildung der 1,2-cis-verknupften β-D-Mannofuranoside und -pyranoside wird durch intramolekulare Komplexierung der 1-O-metallierten Spezies erklart. Die so einfach zuganglichen D-Glyceryl-D-mannopyranoside 8 und 9 sind wichtige Bausteine fur Glykolipide und Glykokonjugate. O-Alkylation at the Anomeric Center, 41). 1-O-Alkylation of D-Mannofuranose and D-Mannopyranose From 1-O-metallated 2,3: 5,6-di-O-isopropylidene-D-mannose (1) and strong alkylating agents (triflates) β-D-mannofuranosides were obtained, addition of crown ether resulted in α-D-mannofuranoside formation. From the 6-O-unprotected D-mannose 7 a similar stereoselectivity change to β- or α-D-mannopyranosides was reached by temperature variation. The convenient formation of the 1,2-cis connected β-D-mannofuranosides and -pyranosides is explained by intramolecular complexation in the 1-O-metallated species. The easily accessible D-glyceryl-D-mannopyranosides 8 and 9 are important intermediates for glycolipids and glycoconjugates.

Respiration of blue-green algae in the light

Abstract: The CO2 evolution in the light of Anabaena as well as several other blue-green algae is below 10% of the dark control. Addition of DCMU restores CO2 evolution in the light almost to the dark level. Furthermore, by adding unlabeled NaHCO3, a 14CO2 release is observed with prelabeled algal cells attaining 15 to 100% of dark control. Analysis by double-reciprocal plots exhibits a competitive relationship between added and endogenously released carbon dioxide. We conclude that CO2 evolved by respiration is immediately refixed in the light without being liberated. The degree of 14CO2 release induced by unlabeled bicarbonate in the light allows to determine true photoinhibition of respiration. Anabaena variabilis Kutz. exhibits almost no inhibition while in eight other species respiration is light-inhibited between 50 and 85% of the dark control.