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  • 1970-1974  (43,639)
  • 1971  (43,639)
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Year
  • 1
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    New York, NY : Elsevier
    Keywords: Biochemistry ; Enzymes
    Notes: This is a series title, single volumes see link below.
    ISSN: 1557-7988
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  • 2
    Call number: QZ200Z:41
    Keywords: Oncology / Congresses
    Notes: Holdidngs of ZB: 1964-1988; Please search for single title in "Signatur" QZ200Z:41
    ISSN: 0069-4800
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  • 3
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    Stuttgart : Enke
    Call number: WB700:12(2)/1/Mag ; WB700:12(2)/2/Mag ; WB700:12(2)/3/Mag
    Description / Table of Contents: 1. Abth. Die allgemeinen acuten Infectionskrankheiten.--2. Abth. Die chronischen Infections- und Intoxications-Krankheiten, parasitäre Krankheiten, infectiöse Wundkrankheiten und chronische Ernährungs-Anomalieen.--3. Abth. Die Organkrankheiten
    Pages: 3 v.
    Edition: 2. vollständig neue Bearbeitung.
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    WB700:12(2)/3/Mag departmental collection or stack – please contact the library
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  • 4
    Call number: ZZ1980:9/Mag
    Keywords: Deutsches Krebsforschungszentrum Heidelberg ; Oncology / Database ; Bibliometrics ; DKFZ-publications
    Notes: Werke verschiedenner Autoren
    Pages: various pagings
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  • 5
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    New York : Academic Press
    Call number: 09-MA:499/2 ; 09-Ma:499/3 ; 09-MA:499/4 ; 09-MA:499/5 ; 09-MA:499/6
    Notes: Transl. of: Élements d'analyse. T. 2-6. Paris: Gauthier-Villars. 1969-1975
    Pages: 5 v.
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    09-MA:499/4 departmental collection or stack – please contact the library
    09-MA:499/5 departmental collection or stack – please contact the library
    09-MA:499/6 departmental collection or stack – please contact the library
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Communications in mathematical physics 22 (1971), S. 238-252 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The construction of independentSU (3) tensors out of octets of fields is considered by investigating numerically invariantSU (3) tensors. A method of obtaining independent sets of these to any rank is discussed and also independent sets are explicitly displayed up to fifth rank. It is shown that this approach allows us to obtain relations among the invariant tensors, and useful new identities involving thed ijk andf ijk tensors are exhibited.
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  • 7
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We give a new proof that the locally correct HamiltonianH(g) is self adjoint, and that the vacuum energyE(g)=inf spectrumH(g) satisfies −O(D)≦E(g), where 0≦g≦1 andD=diam.supp.g.
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  • 8
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We study a class of symmetric relatively compact perturbations satisfying analyticity conditions with respect to the dilatation group inR n. Absence of continuous singular part for the Hamiltonians is proved together with the existence of an absolutely continuous part having spectrum [0, ∞). The point spectrum consists in R−{0} of finite multiplicity isolated energy bound-states standing in a bounded domain. Bound-state wave functions are analytic with respect to the dilatation group. Some properties of resonance poles are investigated.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Communications in mathematical physics 22 (1971), S. 295-300 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract LetA be a positive selfadjoint operator and letB be a symmetric perturbation ofA. We establish sufficient conditions for the essential selfadjointness ofA+B on domains whereA is essentially selfadjoint. The results have application to the λφ4 field theory in two space-time dimensions.
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  • 10
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract It is shown that in all solutions of the Einstein-Boltzmann equations in which the particle distribution function is isotropic about some 4-velocity field, the distortion of that velocity field vanishes; further, either its expansion or its rotation vanishes. We discuss briefly further kinetic solutions in which the energy-momentum tensor has a perfect fluid form.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Communications in mathematical physics 22 (1971), S. 321-337 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The role of co-moving atlases is discussed in connection with a possible formulation of the problem of motion in General Relativity. The concept of co-moving scheme is defined and applied to various cases of physical interest. In particular in the Einstein-Maxwell case, we derive a general uniqueness proof for the Maxwell equations. The dynamical meaning of the equationT j ij =0 is proved, and a scheme for the solution of the problem of motion in co-moving co-ordinates is proposed.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract A direct proof is given that analytic renormalization has an additive structure and hence may be implemented by counterterms in the Lagrangian.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We discuss the fundamentals of classical particle scattering of a two body system in forces which are 0 (r−2−ε) at infinity along with their Lipshitz constants. We prove asymptotic completeness for this two-body case. Of particular interest is the fact that in the absence of control on Lipshitz constants at ∞, two solutions of the interacting equation may be asymptotic to the same free solution at −∞.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract A Markov process which may be thought of as a classical lattice spin system is considered. States of the system are probability measures on the configuration space, and we study the evolution of the free energy of these states with time. It is proved that for all initial states the free energy is nonincreasing and that it strictly decreases from any initial state which is shift invariant but not an equilibrium state. Finally we show that the state of the system converges weakly to the set of Gibbsian Distributions for the given interaction, and that all shift invariant equilibrium states are Gibbsian Distributions.
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract A previously described method to obtain the asymptotic forms of vertex functions at large momenta is, with the help of Wilson operator product expansion formulas, extended to momenta where the vertex functions of the zero-mass theory underlying the asymptotic forms are infrared singular. To obtain from asymptotic forms information on asymptotic behaviour requires assumptions on the behaviour of the zero-mass theory in the limit of infinite dilatation. One particular set of assumptions is discussed and found to pass a simple consistency test; this set of assumptions leads to power laws, or slight modifications thereof, with coupling-constant-independent exponents. The detailed discussion is given for the ф4 model.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Communications in mathematical physics 23 (1971), S. 100-116 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
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  • 17
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract This contribution continues the series of papers [2, 4, 5, 12] treated by Ludwig and collaborators. It is based on the generalized frame given in [6]; there Ludwig has set up an “infinite” axiomatic scheme as extension of the “finite” system [4, 5]. The results of [12] are then proved for a “locally finite” case; they lead to an extended representation theorem.
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  • 18
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The general stationary vacuum gravitational field of cylindrical symmetry as recently found by Davies and Caplan is even static. The possible Petrov types of the Riemann tensor areI,D orO. In spacelike infinity the spacetime becomes necessarily flat.
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  • 19
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract Spherical functions of the Lorentz group with respect to the horyspheric subgroup are derived and their relation to Gelfand's homogeneous functions are discussed.
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  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Communications in mathematical physics 23 (1971), S. 137-158 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract Standard geometric techniques of differential equation theory are employed to determine the qualitative behaviour of a set of non-rotating perfect-fluid cosmologies, whose spatially homogeneous hypersurfaces admit a 3-parameter group of isometries of Bianchi types I, II, III, V, or VI. In this way we are led to some new exact solutions of the field equations. The field equations for a broad class of cosmological models are presented in a regularised form, limitations on the use of this procedure are examined, and some suggestions are made of ways of avoiding the difficulties that arise.
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  • 21
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract It is shown that the pressure is a strictly convex function of the translationally invariant interactions (under certain mild restrictions on the long-range part of these interactions) for classical and quantum lattice systems, by demonstrating that two distinct interactions can never lead to the same translationally invariant equilibrium state. This generalizes a previous result that the pressure is a continuous function of density at fixed temperature.
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  • 22
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract It has hitherto been accepted that the degree of the Harish-Chandra condition applying to single-mass equations of arbitrary spin is determined by the maximum spin appearing in the representation ofSL(2,C) which acts on the field. The present paper demonstrates a fallacy in the published arguments which lead to the above conclusion, and gives the correct conclusion which can be deduced from the hypotheses. A counter-example of an irreducible, single-mass, spin 3/2 equation which does not satisfy the accepted theory is provided in an appendix.
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  • 23
    Electronic Resource
    Electronic Resource
    Springer
    Communications in mathematical physics 23 (1971), S. 159-168 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We describe a new approach to the general theory of unitary representations of Lie groups which makes use of the Gelfand-Segal construction directly on the universal enveloping algebra of any Lie algebra. The crucial observation is that Nelson's theory of analytic vectors allows the characterisation of certain states on the universal enveloping algebra such that the corresponding representations of the universal enveloping algebra are the infinitesimal part of unitary representations of the associated simply connected Lie group. In the first section of the paper we show that with the aid of Choquet's theory of representing measures one can derive a simple new approach to integral decomposition theory along these lines. In the second section of the paper we use these methods to study the irreducible unitary representations of general semi-simple Lie groups. We give a simple proof that theK-finite vectors studied by Harish-Chandra [5] are all analytic vectors. We also give new proofs of some of Godement's results [2] characterising spherical functions of height one, at least for unitary representations. Compared with [2] our method has the possible advantage of obtaining the characterisations by infinitesimal methods instead of using an indirect argument involving functions on the group. We point out that while being purely algebraic in nature, this approach makes almost no use of the deep and difficult theorems of Harish-Chandra concerning the universal enveloping algebra [5]. Our work is done in very much the same spirit as that of Power's recent paper [8]. The main difference is that by concentrating on a more special class of positive states we are able to carry the analysis very much further without difficulty.
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  • 24
    Electronic Resource
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    Communications in mathematical physics 23 (1971), S. 189-198 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract By introducing a specific type of perturbation,A, in the Hamiltonian, we define a class of gently perturbed states, ϱβ,A, of a canonical ensemble, ϱβ. The perturbations are chosen so as to preserve a relationship of the form ϱβ,A≦ constant ×ϱβ. Applications in ergodic theory and phase transitions are described.
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  • 25
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
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  • 26
    ISSN: 1432-1041
    Keywords: Beta adrenergic receptor blockade ; nitrates ; placebo ; coronary artery disease ; exercise tests
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary 16 patients with coronary insufficiency on exertion were submitted to standardized work tests using a bicycle ergometer, after oral doses of placebo (PP), 5 mg sorbidnitrate + placebo (PS), 100 mg alprenolol (adrenergic beta-blocker) + placebo (AP) and 100 mg alprenolol + 5 mg sorbidnitrate (AS), allocated randomly in a double-blind trial. Total work done, work until pain, and work until the appearance of ST-depression increased significantly in the tests where an active drug had been used. The mean increase in total work was 44% for AS, 35% for AP and 26% for PS. AS was “best drug” in 11 of 16 patients, indicating a moderate synergism between its constituents. The greater heart rate increase in PS tests was completely blocked by alprenolol. Angina occurred at a significantly lower heart rate after both AP and AS. Half of the patients experienced some discomfort, usually headache, after PS or AS. No unusual side-effects were noted after alprenolol.
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  • 27
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-1041
    Keywords: Verapamil ; haemodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The haemodynamic effect of verapamil has been studied in twelve patients during diagnostic cardiac catheterisation. The dose administered was 0.1 mg/kg body-weight given as an i. v. injection followed immediately by continuous infusion of 0.005 mg/kg body-weight per minute for thirty minutes. The total amount of verapamil administered varied between 13.0 and 21.6 mg. Brachial and pulmonary artery pressure, cardiac output, stroke volume, heart rate and peripheral vascular resistance were studied as well as atrioventricular conduction. — In patients in sinus rhythm no significant haemodynamic effects were observed, despite a significant increase in the atrioventricular conduction time. One patient developed second degree atrioventricular block, and several others showed first degree blocks. Two digitalized patients with atrial fibrillation were examined. Their results differed as they showed significant decreases in ventricular rate, blood pressure and cardiac output despite some increase in stroke volume. — On the basis of these results it was concluded that verapamil does not seem to have any haemodynamically unfavourable effects in the doses used. However, until further experience has been gained, verapamil should be used with caution in patients with atrial fibrillation who have already been digitalized. Verapamil should also be used with great care in persons with disturbed atrioventricular conduction and should not be given at all to patients with AV block of the second and third degree.
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  • 28
    ISSN: 1432-1041
    Keywords: Parkinson's disease ; L-DOPA ; decarboxylase inhibitor ; psychomotor performance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Twenty patients with parkinsonism were given a series of psychomotor tests before and during treatment with L-DOPA combined with a decarboxylase inhibitor. This new therapeutic combination produced greater improvement of performance in simple motor activities than in tests which required an ordered sequence of movements or decision taking. It is concluded that L-DOPA combined with a decarboxylase inhibitor acts mainly on efferent motor pathways rather than on afferent sensory pathways, or on the central nervous structures responsible for the programming and planning of actions.
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  • 29
    ISSN: 1432-1041
    Keywords: Analgesic ; antipyretic ; antiphlogistic ; intestinal absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The excretion kinetics and blood levels of alclofenac (14C-carbonyl) have been investigated in 9 patients treated orally (400, 800 or 1200 mg single dose) or rectally (400 mg single dose). The results obtained have shown that: 1) the absorption and excretion of oral alclofenac are highly effective and rapid at the dose levels tested; 2) the blood levels are directly dose-related but cannot be correlated quantiatively with the urinary excretion; 3) binding of the drug to erythrocytes is only detectable at high blood levels; 4) rectal and oral administration are equally effective; 5) the analgesic activity of alclofenac is related to its blood concentrations.
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  • 30
    ISSN: 1432-1041
    Keywords: Antihistaminics ; triprolidine ; histamine ; experimental design ; cyclizine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A new method for evaluating histamine antagonists in man is described based on diminution of the effects of intradermal histamine. The inter and intra subject variability of such effects is examined experimentally and previous descriptions reviewed. Measures are adopted to minimise the effects and so achieve maximum economy of drug administrations and subjects. The method is exemplified by comparisons of activity of different preparations of triprolidine and of cyclizine and chlorcycline.
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  • 31
    ISSN: 1432-1041
    Keywords: Biguanides ; butylbiguanide ; pharmacokinetics ; sustained release form
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In man, after oral administration of 50 mg14C-butylbiguanide, the maximum serum concentration was 26–41 µg/100 ml. The biguanide was eliminated with an average half-life of 2h. 84% of the dose administered was found excreted unchanged in the urine. — After administration of14C-butylbiguanide in a sustained release form (Silubin® retard), the drug was slowly released and its serum concentration remained almost constant for up to 7 h.
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  • 32
    ISSN: 1432-1041
    Keywords: Parkinsonism ; 5-hydroxyindoleacetic acid ; cerebrospinal fluid ; L-DOPA ; homovanillic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary 5-Hydroxytryptamine (5-HT) turnover has been studied in eleven patients with Parkinson's disease before and during L-DOPA administration, using a test based on the fact that probenecid inhibits the active transport of acid monoamine metabolites, such as 5-hydroxyindoleacetic acid (5-HIAA), from cerebrospinal fluid to blood. A significant decrease in 5-HT turnover was observed during L-DOPA treatment, and possible mechanisms for it are discussed.
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  • 33
    ISSN: 1432-1041
    Keywords: Flavonoids ; blood flow ; venous distensibility ; capillary filtration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We studied the effect of 0-(β-hydroxyethyl)-rutosides (HR), (Venoruton®, Zyma) upon resting blood flow, venous distensibility and capillary filtration coefficient in the calf in 5 women with idiopathic oedema. — During 60 min of i.v. infusion of 1000 mg HR, the value of the capillary filtration coefficient which is the measure of the size of the capillary filtration area decreased. — After 30 days peroral treatment with 3 × 300 mg HR per day the initial values of the capillary filtration coefficient were proved to have decreased. — After 30 days of oral treatment, the HR infusion was of equal effect upon decrease of the capillary filtration coefficient as in the first infusion before treatment. — No effect of the drug upon values of resting blood flow and venous distensibility was observed. — We believe HR to diminish the capillary area by causing constriction of the precapillary sphincters.
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  • 34
    Electronic Resource
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    ISSN: 1432-1041
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
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  • 35
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Whole cells of Rhodospirillum rubrum were cultivated in a malate medium lacking bound nitrogen under N2 and tested for their nitrogenase activity by measuring the disappearance of nitrogen manometrically. Several experimental conditions were relevant in maintaining consistently high activities. These included: a) light intensity, b) substrate concentration, c) concentration of the cell suspension, d) buffer molarity, pH, and e) temperature. Under our optimal experimental conditions about 6 moles of either l-malate, fumarate, succinate or 10 moles of pyruvate were consumed per 1 mole of molecular nitrogen. The amount of gas taken up by the cells agreed quantitatively with the increase of bound nitrogen found in the cells by microkjeldahl determinations. The fixation of molecular nitrogen is suppresed quickly and specifically by very small amounts of ammonia (〈5 μg ammonia N/ml). The duration of this inhibition depends on the amount of ammonia available to the cells.
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  • 36
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Rhodospirillum rubrum was grown: 1. photoheterotrophically on a medium containing dl-malate as the carbon source and ammonium chloride as the nitrogen source (medium No. 1); 2. phototrophically with N2 and dl-malate (medium No. 2); 3. photoautotrophically with N2, CO2 and H2 (medium No. 3). Resting cells derived from these cultures were tested for their ability to photoreduce CO2, evolve H2 and fix N2. Only cells which were grown in medium No. 2 were able to perform all three gas exchanges. The activity pattern of gas exchanges altered in a characteristic way during the growth cycle of the bacterial culture. Cells newly transferred to medium No. 2 showed an enormous increase in the rate of H2 evolution, which dropped sharply when all l-malate had been used up. The rate of photoreduction of CO2 increased steadily and reached a maximum level after 120 h. The nitrogen fixing activity remained constant during the whole growth cycle. The yields of H2 produced per mole of l-malate added were measured as a function of cell age. Only very young cultures gave appreciable yields, which dropped gradually with increasing age. The function of the carbon source is discussed as a regulating factor for photoreduction and hydrogen evolution.
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  • 37
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die von Kornmann 1965 zuerst beschriebene einzellige, marine Rotalge Porphyridium violaceum wurde elektronenmikroskopisch im Vergleich mit anderen Porphyridium-Arten untersucht. Ihre Organisation ist von den bisher studierten Porphyridium-Arten wesentlich verschieden, 1. durch die stärker aufgegliederte, verzweigt-lappige Plastide, 2. durch den thylakoidfreien Bau des Pyrenoids, 3. durch das Vorkommen von Stroma und Plastiden-DNS nur in den peripheren Plastidenteilen, und 4. durch die nichtparietale Lage des Zellkerns innerhalb der Zelle. Da alle diese merkmale von P. violaceum eher mit der Gattung Rhodella übereinstimmen, die am Beispiel von Rh. maculata eben erst von Evans (1970) beschrieben wurde, als mit der Gattung Porphyridium, wird vorgeschlagen, P. violaceum in diese neue Gattung zu überführen. Auf der anderen Seite ist P. violaceum bestimmt nicht mit Rhodella maculata identisch.
    Notes: Summary The unicellular marine red alga, Porphyridium violaceum, primarily described by Kornmann in 1965, was investigated by electron microscopy in comparison to other Porphyridium-species. Its organization differs remarkably from any previously studied species of the genus Porphyridium by 1. the highly subdivided, branched and lobed plastid, 2. the structure of its pyrenoid free from thylakoids, 3. the arrangement of stroma and plastid-DNA exclusively in the peripheral parts of the plastid, and 4. the non-parietal position of the nucleus in the cell. Since all these features of P. violaceum coincide rather with the genus Rhodella, just described by the example of Rh. maculata by Evans (1970), than with the genus Porphyridium, it is proposed to transfer P. violaceum to the new genus. On the other hand P. violaceum is certainly not identical with Rhodella maculata. The phycobilisomes (cf. Gantt and Conti, 1967) of the species are disk-shaped, aggregated in rows of stacked piles, and arranged in specific patterns on the surface of the thylakoids.
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  • 38
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    Archives of microbiology 75 (1971), S. 110-120 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Rhodospirillum rubrum was grown in a malate medium without bound nitrogen anaerobically under N2. 1. Resting cells of these cultures showed a gradual decrease in photoreducing activity (light-induced consumption of CO2 with H2). Small amounts of ammonium chloride immediately restored the initial activity. 2. A stoichiometric relationship was found between the amount of ammonium chloride added and the amount of gases which disappeared during the ensuing photoreduction: 8 H2 and 4 CO2 were taken up per mole NH3. 3. Addition of l-malate under photoreducing conditions (=atmosphere of 4% CO2 in H2) led to a substrate dependent gas evolution of H2 and CO2. Simultaneous addition of l-malate and various amounts of ammonium chloride gave at first only a comparatively small gas evolution which levelled off into a plateau. 4. The subsequent gas exchange following this first step depended upon the ratio of l-malate to NH4Cl. Titration of l-malate revealed that 2.2±0.3 moles of malate were consumed per mole of ammonium chloride. If there were more than 2.2 moles of malate present per mole of ammonium chloride, gas evolution was resumed after a characteristic time interval. If, on the other hand, there was less malate available, a strong gas uptake, photoreduction, was initiated. 5. In the presence of NH4Cl, malate was metabolized about 3 times faster than in its absence. 6. These observations are discussed in regard to the interrelationships between photosynthetic CO2 reduction, nitrogen fixation and protein metabolism of R. rubrum.
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  • 39
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The yeast fungus Dipodascus aggregatus was cultivated aerobically on different carbon sources. The growth was measured turbidimetrically and related to the simultaneus production of volatile compounds, which was determined by a gas chromatographic head-space technique. The same culture could be analyzed many times and up to 15 components were detected in a chromatogram recorded in 18 min. The main peaks were identified and the chromatograms quantitatively evaluated by peak height measurements. All the carbon sources tested were utilized for growth even if the lag phase was prolonged on xylose and ethanol. The production of volatile compounds from the different carbon sources decreased as follows; ethanol〉glucose〉fructose〉glycerol 〉xylose and succinic acid. A good carbon source for growth could be unsuitable for the formation of volatile products and vice versa. The time course production of volatile components was recorded. On each separate carbon source the formation of volatiles was correlated to growth until the end of the exponential phase of growth. An extraction procedure including the addition of an internal standard was used to determine the exact concentrations of 9 components at near optimum production. The amounts varied between 0.1–32 mg/l medium when the fungus was grown on 5% glucose.
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  • 40
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    Archives of microbiology 75 (1971), S. 140-144 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Um die Beteiligung phenolätherspaltender Enzyme am Ligninabbau der Weißfäulepilze zu prüfen, wurden Untersuchungen mit Phenoxyäthanol und Glycerin-α-guajacyläther durchgeführt. 1. Beim Ringschalen-Test mit Phenoxyäthanol und Glycerin-α-guajacyläther in 0,15% Konzentration entstand bei den Weißfäulepilzen Pleurotus ostreatus und Polystictus versicolor in der Zone mit der Testsubstanz eine Rotfärbung besonders an der Mycelunterseite, und zwar intensiver durch Phenoxyäthanol. Diese Vitalfärbung war besonders ausgeprägt an Hyphenenden von Polystictus versicolor, wobei sich die Schnallen deutlich abzeichnen. Die Ursache dieser Farbreaktion wird mit Nährlösungskulturen untersucht. 2. In den Kontrollen nach dem Agarplattenverfahren war auf dem Testagar die Mycelentwicklung beider Pilze stark gehemmt, und schwache Farbreaktionen entstanden nur vereinzelt. In den Ringschalen dagegen wuchs das Mycel beider Pilze über die Testzone. Die Befunde mit Phenoläther-Substraten bestätigen die in der I. Mitteilung mit einfachen phenolischen Verbindungen nachgewiesene methodische Verbesserung durch den Ringschalen-Test gegenüber dem Agarplattenverfahren.
    Notes: Summary In order to investigated the participation of phenolether-splitting enzymes of white rot fungi on the decomposition of lignin the reactions of phenoxyethanol and glycerol-α-guajacylether have been tested. 1. The ring-dish test with phenoxyethanol and glycerol-α-guajacylether in 0.15% concentration showed a red staining in the test zone at the lower parts of the mycelia of the white rot fungi Pleurotus ostreatus and Polystictus versicolor; phenoxyethanol produced a brighter staining than guajacylether. Vital staining with phenoxyethanol was intensive at the hyphal tips of Polystictus versicolor, with a distinct differentiation of the clamp connections. The cause of these staining reactions is being investigated with liquid cultures. 2. Mycelial development of both the fungi was greatly retarded with the agar plate method and only rarely a sporadic staining occurred. With the ring-dish method the mycelia could grow over the test substrate, where the staining was obvious. The test of phenolether substrates has confirmed, the methodical improvement of the ring-dish test in comparison to the agar plate method as for simple phenolic compounds (cf. Part I).
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  • 41
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Lactic dehydrogenase (LDH) activity has been cytochemically localized and its activity measured in wild-type and mutant strains of Neurospora crassa and male and female hybrids of Allomyces. In all strains, less intracellular staining is found, by oxidative assay of lactic dehydrogenase, ethanol dehydrogenase and a few other dehydrogenases, in the hyphal tips than in the older regions of the hyphae. The extractible activity of LDH, assayed reductively in the soluble fraction, is much greater in Allomyces than Neurospora. In Allomyces the least activity is found in the female differentiated strain. The male differentiated strain and especially the vegetative cultures of both strains have much more activity. In Neurospora, conidiating cultures have unexpectedly more activity than vegetative cultures. The crisp mutant which forms increased numbers of conidia has more activity than the wild-type which, in turn, has more activity than the aconidial fluffy mutant.
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  • 42
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Nitrosospira briensis was isolated from the soils of Crete, the Greek mainland and Switzerland. This is only the second report of the reisolation of a member of this genus since it was described by the Winogradskys in 1933. N. briensis, studied in the present investigation, is so tightly coiled that the cells appear as rods or cylinders rather than spirals when examined with the phase- contrast microscope. On occasion the cells partially uncoil and the spirals are clearly evident even with a phase-contrast microscope. When the cells were thin-sectioned, shadowed, negatively-stained or freeze-etched and viewed with the electron microscope, the spirals were visible even in tightly coiled cells. The tightly coiled cells which appear as rods or cylinders are 1.5–2.5 μ long and 0.8–1.0 μ wide. The cells moved erratically and are propelled by 1–6 flagella which were 3–5 μ long.
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  • 43
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. In 4 von 9 untersuchten Stämmen von Bacillus sphaericus ließ sich eine l-Valin-Carboxylyase nachweisen. 2. Einige Eigenschaften des Enzyms wurden an Acetonpräparaten von B. sphaericus ATCC 245 näher untersucht. Die Decarboxylase reagiert substratunspezifisch mit folgenden Aminosäuren: Valin, Norvalin, Leucin, 2-Amino-n-buttersäure, Norleucin, Isoleucin, Methionin, Alanin und Phenylalanin. Bei gleichzeitigem Angebot zweier Substrate läßt sich kein additiver Effekt feststellen. 3. Das pH-Optimum der Enzymkatalyse liegt bei pH 7,7–7,9, das Temperaturoptimum zwischen 50 und 60°C. 4. Die Decarboxylase wird durch Pyridoxalphosphat (PLP), in geringerem Maße auch durch Pyridoxal, aktiviert. Ohne Zusatz von PLP nimmt die Decarboxylierungsrate stetig ab, und zwar bei Leucin sehr viel schneller als bei Valin; die Decarboxylierung von Valin wird durch Leucin gehemmt. 5. Carbonyl- und SH-Gruppenreagentien hemmen die Decarboxylase. PLP schützt das Enzym in gewissem Umfang gegen die bei Leucin stärker als bei Valin progressiv zunehmende Hemmung durch Jodacetat, kann aber eine bereits eingetretene Inaktivierung nicht wieder aufheben. 6. Die Enzymaktivität ist am höchsten in ganz jungen Kulturen von Bacillus sphaericus; schon zu Beginn des exponentiellen Wachstums fällt sie steib ab.
    Notes: Summary 1. The occurrence of a l-valine carboxy-lyase in Bacillus sphaericus has been demonstrated. The enzyme was found to occur in four out of nine strains tested. 2. Some properties of the decarboxylase were studied in detail using acetonedried cells of B. sphaericus ATCC 245. The substrate-unspecific enzyme decarboxylates the following amino acids: valine, norvaline, leucine, 2-amino n-butyric acid, norleucine, isoleucine, methionine, alanine and phenylalanine. When two substrates are present simultaneously no additive effects are detected. 3. The pH optimum for the reactions is about pH 7.7–7.9, the optimum temperature between 50 and 60°C. 4. The enzyme is activated by pyridoxal phosphate (PLP) and, to a lower extent, by pyridoxal. In the absence of added PLP the rate of decarboxylation decreases continuously. The inactivation occurs more rapidly during decarboxylation of leucine than of valine; added leucine progressively inhibits valine decarboxylation. 5. The decaroxylations are sensitive to reagents known to combine with carbonyl and — SH groups. PLP protects the enzyme to some extent against a progressive inhibition by iodoacetate which is stronger with leucine than with valine. It doesn't, however, reverse inactivation already established. 6. The enzyme activity is highest in very young cultures of Bacillus sphaericus. It decreases rapidly in the early exponential phase of growth.
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  • 44
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Temperature-sensitive nitrogen fixation mutants of Azotobacter vinelandii were obtained by nitrosoguanidine mutagenesis and penicillin selection. The mutants were unable to grow on N2 at 39° but grew normally at 30° on N2 and at both temperatures in the presence of metabolizable nitrogen compounds. Growth experiments and assays of whole cells for nitrogenase activity separated the mutants into two classes: 1. mutants in which the nitrogenase activity present in cells grown at 30° was unaffected by a shift to 39°, and 2. mutants which lost their nitrogen fixation activity after such a temperature shift. Assays of cell-free extracts of the second class of mutants showed that in all cases tested the enzymatic activity of the nitrogenase complex itself was not affected by the mutation. These mutants might therefore contain some other temperature-sensitive proteins specifically involved in nitrogen fixation.
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  • 45
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In exponentially growing cultures of the blue-green alga Microcystis aeruginosa the number of gas vacuoles per cell decreases and reaches a value of 4.5×103 at 1.2×107 cells per ml. The assembly of gas vacuoles with respect to number and length was followed after the organelles were caused to collapse by a pulse of ultrasound. The change in the number N of gas vacuoles per cell is N=224.8×t 0.757, 0〈t〈24 h. After 24 h 50% of the value of non-sonicated cultures is reached. The changes in the length L of the organelles is expressed by L=87.06 ×t 0.4084, 0〈t〈24 h. After 24 h 85% of the control value is reached.
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  • 46
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Freeze-etched hyphae of F. oxysporum exhibited a single layered cell wall; a plasmalemma, in which invaginations were frequently associated with paramural vesicles; cytoplasma bearing lipid droplets, vacuoles, intravacuolar vesicles and nuclei with typical nuclear pores. Some hyphae bore crystalline inclusions characterized by a pronounced hexagonal, external ornamentation and it is suggested that the presence of these crystals and intravacuolar vesicles are indicative of aging hyphae.
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  • 47
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. An aerobic enrichment culture was serially transferred over a long period of time in a salts medium containing cellulose as the only source of carbon. The cultures grew at temperatures of up to 42° and were dominated by a typical microcyst forming Sporocytophaga sp. This was isolated on plates with a soft top layer of agarose containing short pulp fibers. Clear plaques were formed on these plates. 2. The cultures also contained large numbers of a very slender bacterium (measuring approximately 0.1×3–6 μm) which could not be seen under the light microscope. Electron microscopy suggests that this organism is a new kind of bacterium related to the cytophages. Attempts at isolating it in pure culture have not yet been successful. A peculiar starfish-shaped organism was also observed in the cultures. 3. A Gram negative, non-motile eubacterium that could grow on glucose and cellobiose but not on cellulose was isolated. A synergistic effect was noticed when this was grown in mixed culture on cellulose with the Sporocytophaga sp.
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  • 48
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Magnesium and calcium ions were found to enhance barotolerance of Streptococcus faecalis ATCC strain 9790 growing in a complex, glucose-containing medium. Enhancement was indicated both by higher growth rates and yields at 408 atm, and also by an increase in the maximum pressure permitting growth from 550 to 700 atm. The optimum concentration of either ion was ca. 50 mM, and both ions appeared to be equipotent in affecting the same processes by chemically specific interactions. Sodium, potassium, strontium, manganous, chloride, bromide or sulfate ions were all ineffective or only marginally effective in enhancing barotolerance. Mg++ and Ca++ also enhanced growth of compressed, ribose-degrading cultures. Pressure increased the sensitivity of streptococcal growth to low pH, and there appeared to be two distinct effects of Mg++ and Ca++ on barotolerance. First, the rate of exponential growth was enhanced prior to the time at which culture acidity began to limit growth. Second, growth was possible in more acid conditions under pressure when the ions were present, and enhanced yields from compressed cultures were related to this partial reversal of the potentiating effect of high pressure on acid inhibition of growth. Barotolerance of Escherichia coli or Saccharomyces cerevisiae was not enhanced by these ions; while tolerance of two types of chain-forming cocci freshly isolated from a rotting mussel was enhanced.
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  • 49
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. A simple technique is described for obtaining large numbers of localized and synchronized fruit bodies of Schizophyllum commune by lowering the carbon dioxide level in mated cultures. 2. The fruiting process is unaffected by a continuous supply of glucose (0.4–2%). However, synchrony and commitment are lost when the glucose concentration is raised to 4%. 3. Five per cent carbon dioxide inhibits the further development of fruit bodies at all stages except the expansion of the already formed basidiocarp. 4. Fruit bodies can develop at 30°C when a CO2 trapping agent is employed, contrary to previous reports. 5. A possible relationship between the rate of vegetative growth and the initiation of fruiting is discussed.
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  • 50
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    Archives of microbiology 75 (1971), S. 260-265 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Conspicuous cell agglutination occurred when cells of the a and α types were mixed together and cultured, while it did not when the strains not to mate each other were mixed. In the former case the ability of cells to agglutinate developed gradually with time after the mixing. The agglutination was inhibited by cycloheximide but not by chloramphenicol. Relation between yeast sexual hormones and the mating-specific cell agglutination is discussed.
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  • 51
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    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Various fixation and embedding procedures were tested on the retention of immunofluorescent staining. Intact hyphae of Ophiobolus graminis Sacc. were fixed in various aldehyde solution both before and after indirect immunofluorescent staining. Paraformaldehyde and glutaraldehyde solutions did not affect the intensity of fluorescence while acrolein quenched fluorescence slightly. 2. Immunofluorescent stained hyphae fixed in 3% glutaraldehyde, dehydrated, embedded in glycol methacrylate and sectioned at 1–2 μm retained fluorescence allowing more precise location of the antigen.
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  • 52
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The cytology of Podospora arizonensis, an apomictic pyrenomycete, has been studied from crozier formation to the first mitotic division in the ascus, using phase contrast light microscopy. Increase in ascus size is accompanied by morphological changes in the chromosomes which are reminiscent of the changes associated with meiosis in normal ascomycetes. The nucleolus is seen to increase in size during the phase of maximal ascus growth, and to decrease thereafter. The significance of these events is discussed.
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  • 53
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Während der aeroben Vergärung von Glucose wurde die Konzentration von Acetaldehyd im Gärmedium über den gesamten Gärablauf bei mehreren Stämmen von Saccharomyces cerevisiae verfolgt. Die Aldehydkonzentration weist bei Glucosekonzentrationen zwischen 5 und 20% zwei Maxima auf. Damit ist der Konzentrationsverlauf von Acetaldehyd aerob wesentlich anders als bei der anaeroben Gärung, mit nur einem meist niedrigen Maximum. 10-3 M Azid hemmt die Bildung von Acetaldehyd ganz oder weitgehend. Das deutet auf die Funktion bzw. Synthese der Cytochrome, die in Gegenwart von Sauerstoff offensichtlich auch bei hohen Glucosekonzentrationen nicht vollständig reprimiert werden. Der durch die Atmung bedingte Wasserstoffabfluß führt zu höheren Aldehydkonzentrationen. Der in der logarithmischen Wachstumsphase vorwiegend fermentative Stoffwechsel überlagert mit seiner starken Wasserstoffproduktion die Atmung, was zum Auftreten von zwei Aldehydmaxima führt. Die Regulation der Acetaldehydbildung während der aerohen Gärung wird eingehend diskutiert und zeigt, daß Acetaldehyd als Indicator für die Induktion und Funktion der Atmungsenzyme geeignet ist.
    Notes: Summary During fermentation of glucose by the yeast Saccharomyces cerevisiae small amounts of acetaldehyde are formed. Anaerobically, acetaldehyde accumulates in the medium, showing only one maximum of ca. 10–30 mg/l in the logarithmic growth phase. During aerobic fermentation, acetaldehyde is formed in higher amounts (160 mg/l) and two maxima are observed. Both maxima appear in glucose concentrations varying from 5–20%. The addition of azide, which inhibits respiration results in a loss of acetaldehyde production. Therefore it is assumed, that the enzymes of the respiratory chain are involved in the formation of acetaldehyde and that acetaldehyde production is caused by induction and function of cytochromes under the influence of oxygen. Various yeast strains differ in their ability of acetaldehyde production. The characteristic appearance of two aldehyde maxima is explained by exceeding hydrogen production in the logarithmic phase of growth, where the fermentation suppresses the influence of respiration on aldehyde production. The regulation of the formation of acetaldehyde during aerobic fermentation is thoroughly discussed showing that acetaldehyde can serve as an indicator for the activity of respiration enzymes in yeast.
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  • 54
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    Archives of microbiology 75 (1971), S. 327-337 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Acid phosphatase was studied by means of electron microscope cytochemistry in glutaraldehyde-fixed myxamoebae of Dictyostelium discoideum grown on dead bacteria. The enzyme activity was localized to the digestive vacuoles in vegetative as well as in aggregating cells. Biochemical experiments showed that the enzyme was not inactivated by fixation in 2% purified glutaraldehyde.
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  • 55
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die p-Aminobenzoesäure-Mangelmutante pab 1 von Chlamydomonas reinhardii ist in der Lage, Chloramphenicol anstelle von p-Aminobenzoesäure als Supplementstoff zu verwenden. Es konnte jedoch gezeigt werden, daß die Algen selbst nicht imstande sind, Chloramphenicol zu p-Aminobenzoesäure abzubauen. Der Abbau erfolgt vielmehr spontan ohne Mitwirkung der Organismen, allerdings nur in belichteten Versuchsansätzen und nicht in Dunkelheit. Die Entstehung der p-Aminobenzoesäure geht über p-Nitrobenzaldehyd. Sie erfolgt rasch und reichlich, so daß für die Mutante ein Wachstum ermöglicht wird, das dem Wildtyp-Wachstum in Minimalmedium entspricht.
    Notes: Summary The p-aminobenzoic-acid mutant pab 1 of Chlamydomonas reinhardii is able to use chloramphenicol as a supplement instead of p-aminobenzoic-acid. Nevertheless, it could be shown, that the algae are not in the position to reduce chloramphenicol to p-aminobenzoic-acid. On the contrary, the decomposition occurs spontaneously without the participation of the organisms, but only in experimental arrangements, exposed to light. The formation of the p-aminobenzoic-acid works rapidly and a high yield via p-nitrobenzaldehyde. Therefore the growth of the mutant is possible, corresponding to the growth of the wildtype cells in minimal-medium.
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  • 56
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    Archives of microbiology 75 (1971), S. 312-326 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Aus dem neu isolierten Arthrobacter Stamm 23 wurde Threonin-Desaminase 11fach angereichert. Das Enzym ist in einem Isoleucin, Pyridoxalphosphat, EDTA und Dithioerythrit enthaltenden Phosphatpuffer von pH 7,9 bei 4° C mehrere Tage lang ohne Aktivitätsverlust haltbar. Für das Enzym wurden Substratsättigungskurven ermittelt, die in Abwesenheit von Isoleucin hyperbolisch, in Gegenwart des negativen Effectors Isoleucin sigmoid verliefen. Der Hill-Koeffizient von n=1,95 deutet auf zwei substratbindende Zentren am Enzymprotein hin. Isoleucin verändert nur den K m-Wert, beeinflußt aber nicht die maximale Reaktionsgeschwindigkeit des Enzyms. Das Enzym wird nicht nur durch Isoleucin, sondern auch durch Valin, Norvalin, Norleucin und im geringen Maße auch durch Leucin und α-Aminobuttersäure gehemmt. Kurzkettige Aminosäuren wie Alanin oder α-Aminoisobuttersäure hemmen das Enzym auch in hohen Konzentrationen nicht. Die Hemmkinetiken mit Isoleucin, Valin, Norvalin und Norleucin verlaufen sigmoid. Die Hill-Koeffizienten deuten auf zwei Bindungsstellen für alle Inhibitoren hin. Antagonistische Effekte zwischen Isoleucin und Valin oder den anderen negativen Effectoren waren nicht zu beobachten. Aus den kinetischen Daten war weiterhin zu schließen, daß die negativen Effectoren Valin, Norvalin und Norleucin an den gleichen Bindungsstellen des Enzymes angreifen wie Isoleucin. Das Enzym läßt sich durch Entzug seiner Effectoren inaktivieren. Eine Reaktivierung gelingt mit Isoleucin, Valin und Threonin und den möglichen Kombinationen dieser Aminosäuren.
    Notes: Summary Threonine deaminase (l-threonine hydro-lyase [deaminating], EC 4.2.1.16) has been partially purified (11-fold) from Arthrobacter strain 23 isolated recently in this laboratory. The enzyme is rather labile in the crude extract and in the partially purified state; in phosphate buffer pH 7.9 containing isoleucine, pyridoxal phosphate, EDTA and dithiothreitol at 4°C it can be kept for several days without loss of activity. The enzyme yielded substrate saturation curves which were hyperbolic unless the inhibitor isoleucine was present. Sigmoid saturation curves were obtained in the presence of isoleucine. The Hill-coefficient of n=1.95 indicates the enzyme to contain two substrate binding sites. Isoleucine changes the K m-value, but does not influence the maximal reaction velocity of the enzyme. The enzyme is not only inhibited by isoleucine, but also by valine, norvaline, norleucine and at a minor degree by leucine and α-aminobutyric acid. It is not inhibited by alanine or α-amino-isobutyric acid, even at high concentrations. Substrate saturation curves determined in the presence of isoleucine, valine, norvaline, and norleucine are sigmoid. The Hill-coefficients indicate the enzyme to contain two binding sites for the inhibitor. Antagonistic effects between isoleucine and valine or the other negative effectors have not been observed. From the kinetic data it can furthermore be concluded that the same binding sites are used by the negative effectors isoleucine, valine, norvaline, and norleucine. When being deprived of its effectors the enzyme becomes inactivated. A reactivation occurs when the enzyme is incubated in the presence of isoleucine, valine, or threonine or combinations of these amino acids.
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  • 57
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Enzymatic and genetic evidence are presented for a new pathway of ammonia assimilation in nitrogen fixing bacteria: ammonium → glutamine → glutamate. This route to the important glutamate-glutamine family of amino acids differs from the conventional pathway, ammonium → glutamate → glutamine, in several respects. Glutamate synthetase [(glutamine amide-2-oxoglutarate aminotransferase) (oxidoreductase)], which is clearly distinct from glutamate dehydrogenase, catalyzes the reduced pyridine nucleotide dependent amination of α-ketoglutarate with glutamine as amino donor yielding two molecules of glutamate as product. The enzyme is completely inhibited by the glutamine analogue DON, whereas glutamate dehydrogenase is not affected by this inhibitor; the glutamate synthetase reaction is irreversible. Glutamate synthetase is widely distributed in bacteria; the pyridine nucleotide coenzyme specificity of the enzyme varies in many of these species. The activities of key enzymes are modulated by environmental nitrogenous sources; for example, extracts of N2-grown cells of Klebsiella pneumoniae form glutamate almost exclusively by this new route and contain only trace amounts of glutamate dehydrogenase activity whereas NH3-grown cells possess both pathways. Also, the biosynthetically active form of glutamine synthetase with a low K m for ammonium predominates in the N2-grown cell. Several mutant strains of K. pneumoniae have been isolated which fail to fix nitrogen or to grow in an ammonium limited environment. Extracts of these strains prepared from cells grown on higher levels of ammonium have low levels of glutamate synthetase activity and contain the biosynthetically inactive species of glutamine synthetase along with high levels of glutamate dehydrogenase. These mutants missing the new assimilatory pathway have serious defects in their metabolism of many inorganic and organic nitrogen sources; utilization of at least 20 different compounds is effected. We conclude that the new ammonia assimilatory route plays an important role in nitrogenous metabolism and is essential for nitrogen fixation.
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  • 58
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    Archives of microbiology 75 (1971), S. 353-359 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Principe. Les nitrate-réductases A et B utilisent le méthyl-viologène comme donneur d'électrons. Cet indicateur d'oxydoréduction est réduit, en anaérobiose, par un excès d'hydrosulfite. Le nitrite produit est dosé par colorimétrie. Enzyme A. L'activité demeure constante pendant 30 min au moins après le début de la réaction et elle varie proportionnellement à la concentration d'enzyme. Enzyme B. L'activité diminue rapidement et de façon continue dès le début de la réaction. Conclusion. La méthode colorimétrique perment de mesurer l'activité de l'enzyme A. Par contre, elle est inapplicable à l'enzyme B.
    Notes: Summary Principle. Nitrate reductases A and B use methyl viologen as an electron donor. This oxidation-reduction indicator is reduced, in anaerobic conditions, by an excess of dithionite. The nitrite produced is estimated by colorimetry. Enzyme A. The activity is stable for at least the first 30 min of the reaction and it is proportional to enzyme concentration. Enzyme B. The activity decreases rapidly and continuously from the start of the reaction. Conclusion. The colorimetric method can be used to measure the activity of enzyme A. But it is inapplicable to enzyme B.
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  • 59
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    Topics: Biology
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  • 60
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    Archives of microbiology 75 (1971), S. 374-381 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Motile gram-negative bacteria readily attach to and detach from glass slides, and may remain on them from a few seconds to a number of hours. They attach (a) at one end, (b) along their length showing slight Brownian movement, or (c) along their length remaining quite immobile. No differences were detected between fimbriate and non-fimbriate species. 2. Bacteria that attach at one end appear to do so by their polar flagella. When in this position they rotate in a clockwise or an anticlockwise direction. The rate of rotation is constant for a given time, but can switch to other rates. Rates of 1.7 to 11.7 rotations/sec have been recorded. The rotation of the cells may offer a method of documenting flagellar beat. 3. Bacteria killed by ultraviolet irradiation attach as readily as do living bacteria, but considerably fewer attach when killed by heat or formalin. 4. Bacteria resuspended in dilute solutions of the proteins salmine or albumin attach in fewer numbers than do bacteria resuspended in buffer, while bacteria resuspended in dilute solutions of the proteins casein or gelatin attach in larger numbers. 5. The ecological and cellular consequences of the results are briefly discussed.
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  • 61
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    Springer
    Archives of microbiology 75 (1971), S. 360-373 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. In order to obtain information on morphogenesis the physiological background of abnormally growing strains of Podospora anserina was studied by analysing the influence of different carbon sources on the growth and morphology. The following results were obtained: Galactose inhibits elongation and enhances branching of the wild strain hyphae and thus induces a rhythmic growth pattern similar to that of the mutant zonata. This phenocopy includes other features of this pleiotropic mutant. Addition of glucose prevents the effect of galactose. This leads to the assumption that there is a competitive inhibition by galactose. Induction of reduced and rhythmic growth is brought about by sorbose and 2-deoxy-glucose, too. The resulting colonies, however, are not phenocopies of any of the morphological mutants of P. anserina 2. When the carbohydrate content of the medium is decreased, the rhythmic growth of the mutant zonata is abolished without diminishing its linear growth rate. 3. Although galactose and sorbose inhibit the growth of the mycelia, they do not cause a reduction of glucose or fructose consumption by the mycelia. 4. Zonata and two other rhythmically growing mutants, circulosa and undulata, differ from wild strain by a lower rate of dry weight production related to glucose consumption. 5. The results are discussed under the aspect of a correlation between carbohydrate metabolism and morphogenesis.
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  • 62
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 79 (1971), S. 274-279 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. Evidence is presented that contrary to previous reports a number of enzymes implicated in the TCA cycle are functional in an antibiotic producing strain of Bacillus brevis. 2. The level of enzyme activites recorded was found to be influenced by the permeability state of the cell membrane and by the presence of an NAD+/NADH degrading enzyme. These factors are discussed in relation to the previously reported negative findings of other workers. 3. The distribution and specific activities of TCA cycle enzymes in membrane and supernatant fractions are reported. 4. The results, by comparison with other organisms known to possess a functional TCA cycle, suggest that the cycle provides a major pathway of energy metabolism in B. brevis.
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  • 63
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Vigorous agitation caused the zoospores of Phytophthora palmivora to undergo rapid synchronous encystment. The rate of encystment was determined by counting the number of cells with an alkali-resistant cyst wall. 50% of the zoospores formed an alkali-resistant cyst wall within 60 sec of agitation; after 120 sec, essentially all zoospores had encysted. The rate of spontaneous encystment in nonagitated suspensions was much slower. The flagella of nearly all zoospores disappeared within 30 sec of agitation, i.e. prior to the formation of an alkali-resistant cyst wall. Zoospores depend on internal reserves for synthesizing their cyst walls. Approximately 70% of the total carbohydrate in motile zoospores was extracted with water after treating the cells with 70% éthnol. During synchronous encystment, this carbohydrate fraction composed largely of glucans decreased markedly while the insoluble carbohydrate fraction (cyst wall glucan) increased correspondingly. Clearly, the conversion of cytoplasmic glucan into wall glucan plays a major role in zoospore encystment.
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  • 64
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Walls from cysts, hyphae and sporangia of Phytophthora palmivora consist chiefly (ca. 90% dry wt) of β-glucans with 1,3-, 1,4- and 1,6-links. The glucans are predominatly β-1,3-linked but there are significant differences in the relative proportion of 1,3-, 1,6- and 1,4-linked glucosyl residues among the three wall types. There are also differences in protein content, susceptibility to degradation by various β-glucanases, and surface texture. The isolated cyst wall consists solely of a thin fabric of long, tightly interwoven, randomly oriented microfibrils. Both inner and outer surfaces of the cyst wall are distinctly microfibrillar. The hyphal wall has two different textures; the internal surface is distinctly microfibrillar while the external surface is non-fibrillar. In a germinated cyst, there is a zone of demarcation where the microfibrils of the cyst wall disappear into the smooth outer texture of the germ tube wall. An exo-β-1,3-glucanase preferentially removed the amorphous material of the outer surface of the germ tube leaving exposed a continuous microfibrillar fabric from cyst to hyphal tube. Conceivably, the textural and structural differentiation of the cell wall may play a decisive role in cellular morphogenesis.
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  • 65
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The strength of intact gas vesicle membranes isolated from the bluegreen alga Anabaena flos-aquae was investigated under different physical and chemical conditions some of which might be important in determining their stability in living cells. High concentrations of urea and of divalent cations, pH's above 9 and below 7, exposure to proteolytic enzymes and temperatures over 40°C, all resulted in weakening of the gas vesicles, as indicated by changes in their range of critical-collapse pressure. Detergents gave no apparent increase in critical pressure, suggesting that the interfacial tension at the outer surface of the membrane is very small. Taking these properties into consideration a simple method of isolating intact gas vesicles was improved to give better than 50% recovery and membranes of 97.6% purity. The gas vesicles prepared in this way could be preserved intact by freeze-drying. The stability of gas vesicles in different environments is discussed in relation to their proteinaceous composition.
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  • 66
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Thiobacillus thiooxidans was grown at constant pH. No growth was obtained above pH 4.3. Sulfur was oxidized over the entire range tested (pH 0.9 to 7.0). This was confirmed by pH shift experiments. Carbon dioxide fixation stopped 30 min after shift from low pH to neutral values. On return to high acidity, the rate of CO2 assimilation increased but not always to the original value. The intracellular binding of glycerol which is passively permeable was also inhibited by raising the pH of the medium. The data suggested that ATP formation may be inhibited at neutral pH. Intracellular ATP pool was reduced by 80% on neutralization of the acid growth medium. These results are compared to recent studies on acid-base transients in T. novellus by Cole and Aleem (1971).
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  • 67
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Die Feinstruktur nicht-kontrahierbarer Fimbrien (Pili) der nicht-sternbildenden (sta -) Mutante 3/7 von Pseudomonas echinoides wurde elektronenmikroskopisch untersucht. Hochaufgelöste Aufnahmen negativkontrastierter Fimbrien wurden direkt und mit Hilfe der lichtoptischen Diffraktion analysiert. Die erhaltenen Daten können wie folgt zusammengefaßt werden: Eine sta --Fimbria hat die Gestalt eines Hohlzylinders, dessen Außendurchmesser 65 Å und dessen Innendurchmesser 25 Å beträgt. Die Zylinderwand besteht aus 3 Schrauben mit gemeinsamer Achse und einer Steigung von ca. 20°. Jede Schraube trägt 6 identische, globuläre Untereinheiten pro Umgang. Das Molekulargewicht einer Proteinuntereinheit beträgt 8000; dieser Wert wurde durch SDS-Gelelektrophorese mit Standardproteinen bestimmt. Fr bestätigt die elektronenmikroskopisch erhaltenen Strukturparameter, da beide Ergebnisse unabhängig zum gleichen Volumen für eine Fimbrienuntereinheit führen. Aus diesen Daten wurde ein Feinstrukturmodell der sta --Fimbria aufgestellt und seine Übereinstimmung mit der Originalstruktur durch lichtoptische Diffraktion bestätigt. Dieses Modell wurde ferner zur Deutung der Struktur nicht-kontrahierter Fimbrien des sternbildenden (sta +) Wildtyps benutzt. Ausgehend von dieser Modellvorstellung nicht-kontrahierter sta +-Fimbrien und früheren Beobachtungen an kontrahierten sta +-Fimbrien (Mayer, 1971), wurde ein Arbeitsmodell für die Fimbrienkontraktion postuliert.
    Notes: Summary The fine structure of non-contractible fimbria (pili) of the nonstarforming (sta -) mutant strain 3/7 of Pseudomonas echinoides has been investigated by electron microscopy. High resolution photographs of negatively stained fimbria have been analyzed directly and by optical diffraction. The data obtained can be summarized as follows. The sta --fimbria is a hollow cylinder of 65 Å outer and 25 Å inner diameter. The cylinder consists of three helices with a common axis having a pitch of about 20°. Each helix carries 6 identical, globular subunits per turn. The molecular weight of one protein subunit is 8.000; this value has been determined by SDS gel electrophoresis with standard proteins. It confirms the structural parameters obtained by electron microscopy since both results independently lead to the same volume for one subunit. From this data a fine structure model for the sta --fimbria has been built which is in agreement with the original structure as demonstrated by its diffraction pattern. This model has been also employed for interpreting the structure of non-contracted fimbria of the starforming (sta +) wild type strain. From this concept of non-contracted sta +-fimbria together with earlier observations of contracted sta +-fimbria (Mayer; 1971) a working model for the contraction of fimbria has been proposed.
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  • 68
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 79 (1971), S. 345-353 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In sulfide limited continuous culture of a marine isolate of Chromatium vinosum, sulfide was undetectable in steady states below dilution rates of 0.06h-1, that is 1/2 of the maximum specific growth rate. In the same range, sulfur is assumed to attain the role of the growth rate limiting substrate. Furthermore, it could be shown that the rate of sulfur oxidation is a function of the surface area of the sulfur globules rather than of the sulfur concentration. In completely filled chemostats, steady states were obtainable only at dilution rates not exceeding 0.09 h-1. In the presence of a nitrogen flushed gas phase, steady states were obtained at dilution rates approaching the maximum specific growth rate (0.12h-1). This phenomenon is ascribed to the particular sulfide tolerance of our strain of Chromatium vinosum. The saturation constant and the inhibition constant (lowest, respectively highest total sulfide concentration at which the specific growth rate is equal to one-half of the maximum specific growth rate in the absence of inhibition) were 0.007 mM and 0.85 mM, respectively. The ecological significance of the data is discussed.
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  • 69
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The site of molybdenum action in the metabolic pathway leading from nitrate to ammonia in Chlorella cells has been further investigated. 1. The role of molybdenum is limited to the reduction of nitrate to nitrite catalyzed by the nitrate reductase complex. 2. Molybdenum is not a component of the iron protein nitrite reductase, the second enzyme of the nitrate-reducing system which catalyzes the reduction of nitrite to ammonia. 3. The concentration of molybdate in the culture medium—which markedly affects the cellular level of nitrate reductase activity—does not have any effect upon the level of nitrite reductase. 4. Neither nitrate or nitrite nor molybdate is required for the synthesis of nitrite reductase, but ammonia acts as a nutritional repressor of the enzyme. 5. When nitrite is substituted for nitrate as the only nitrogen source, growth is unaffected by tungstate concentrations which completely prevent the utilization of nitrate. 6. The addition of tungstate to the culture medium—which results in the loss of nitrate reductase activity—does not influence or even stimulates the level of nitrite reductase.
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  • 70
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The effects of eighteen l-amino acids and two peptides, added individually to an otherwise autotrophic medium, on the growth of Thiobacillus thioparus, Thiobacillus neapolitanus and Thiobacillus thiooxidans were tested. Under these conditions, specific l-amino acids, which differed for each of the thiobacilli, inhibited growth. 2. All inhibitory effects were reversed, completely or in part, in the presence of non-inhibitory concentrations of casein hydrolysate. 3. l-tyrosine or l-tryptophane reversed the l-phenylalanine inhibition of T. thioparus and T. neapolitanus; l-serine inhibition of T. thiooxidans was partially reversed by l-threonine and completely by l-valine plus l-leucine; and l-valine inhibition of T. thiooxidans was similarly reversed by l-leucine or l-isoleucine. 4. In cell-free systems derived from T. thiooxidans, l-valine or l-isoleucine inhibited the activity of acetolactate-forming enzyme. Repression of synthesis of this enzyme by l-valine, l-isoleucine and l-leucine could not be demonstrated. 5. d-valine and d-isoleucine were also inhibitory to T. thioparus. The inhibition by d-valine was not reversed in the presence of any combination of the l-isomers of valine, isoleucine and leucine. 6. It is concluded that inhibition of growth of these three obligately chemolithotrophic thiobacilli by l-amino acids is due to amino acid imbalances that derange normal regulatory processes as also occurs in chemoorganotrophic bacteria.
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  • 71
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two closely similar phycoerythrins were purified from Cryptomonas sp. The two proteins were indistinguishable with respect to native molecular weight, subunit structure, photolability and immunological specificity, and differed only in their isoelectric points (pH 5.74 and 6.35), as determined by isoelectric focussing in polyacrylamide gels. Each protein consisted of two unequal subunits, α (mol. wt. 11,800) and β (mol. wt. 19,000), and each subunit contained covalently bound chromophore. In contrast to the blue-green and red algal phycoerythrins studied thus far, the Cryptomonas sp. phycoerythrins are extremely photolabile; exposure of the purified proteins to relatively short periods of intense illumination with visible light produces a marked decrease in fluorescence and in absorbance at 567 mμ.
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  • 72
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000