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  • 1990-1994  (1)
  • 1970-1974  (45,346)
  • 1960-1964  (3)
  • 1972  (45,346)
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  • 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
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We give conditions for the existence of field operators on so-called null planes and discuss some consequences of the necessary restriction of the test function space, concerning Haag's theorem and the possibility of unitary mappings intertwining between free fields of different masses. In the last section we discuss conditions under which a unitary representation of the dilatations in the null plane gives rise to a unitary representation of the dilatations in Minkowski space.
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  • 7
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The algebra of observables for the renormalized φ4 interaction in 3-dimensional space-time is constructed. It is shown that the von Neumann algebras associated with observables in a bounded regionB are independent of the space cutoff which is used in the construction of a Hamiltonian for this interaction. This result is shown to be useful in the construction of a translation invariant φ4 theory in three dimensions. It also gives a physical criterion for the equivalence of non-Fock representations of the canonical commutation relations.
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  • 8
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    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We investigate the problem of a microscopic definition of the surface of separation between two phases in the special case of the 2-dimensional Ising model. We show how this leads to a definition of the surface tension which appears, in this context, as the logarithm of a partition function over a set of random surfaces. We also discuss the more general problem of defining the surface tension in an Ising ferromagnet with arbitrarily extended attractive interaction.
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  • 9
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    Communications in mathematical physics 25 (1972), S. 172-172 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
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  • 10
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The unitary (pseudo unitary) time-evolution operator for a particle with spin half (zero) in an external time-dependent electromagnetic (scalar) field is used to generate a Bogoliubov automorphism on the algebra of the free in field. For the case of an electric external field (scalar field) a finite expression for Ωout is given and theS-matrix constructed. The latter is unitary and implements the Bogoliubov automorphism. Theorems by Shale and Stinespring are rederived.
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  • 11
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    Communications in mathematical physics 25 (1972), S. 167-171 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract It is shown that a stationary space containing a black hole is a solution of the Brans-Dicke field equations if and only if it is a solution of the Einstein field equations. This implies that when the star collapses to form a black hole, it loses that fraction (about 7%) of its measured gravitational mass that arises from the scalar interaction. This mass loss is in addition to that caused by emission of scalar or tensor gravitational radiation. Another consequence is that there will not be any scalar gravitational radiation emitted when two black holes collide.
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  • 12
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    Communications in mathematical physics 25 (1972), S. 152-166 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract It is assumed that the singularities which occur in gravitational collapse are not visible from outside but are hidden behind an event horizon. This means that one can still predict the future outside the event horizon. A black hole on a spacelike surface is defined to be a connected component of the region of the surface bounded by the event horizon. As time increase, black holes may merge together but can never bifurcate. A black hole would be expected to settle down to a stationary state. It is shown that a stationary black hole must have topologically spherical boundary and must be axisymmetric if it is rotating. These results together with those of Israel and Carter go most of the way towards establishing the conjecture that any stationary black hole is a Kerr solution. Using this conjecture and the result that the surface area of black holes can never decrease, one can place certain limits on the amount of energy that can be extracted from black holes.
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  • 13
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The validity of imposing spatial homogeneity on the variations in the usual action principle for Einstein's equations is studied. It is proved that with this procedure the standard and ADM Lagrangians give correct Einstein equations if and only if the space belongs to Class A of Ellis and MacCallum [1], i.e., the structure constants of the simply transitive group satisfy C fg f =0. The possibility of overcoming this difficulty in the Class B spaces is examined.
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  • 14
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    Communications in mathematical physics 25 (1972), S. 233-244 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The homogeneous, anisotropic cosmological model is considered. It satisfies three physically reasonable conditions: it is space homogeneous, possesses flat space like sections and is filled with expanding, rotating and shearing matter. The asymptotic solution is presented and general properties are discussed. The question how the rotation influences the behaviour of matter near the singularity is investigated.
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  • 15
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    Communications in mathematical physics 25 (1972), S. 245-252 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract A recent justification of the covering law by Jauch and Piron founded on the existence of ideal measurements of the first kind is shown to contain a gap. This gap is closed by an additional assumption about such measurements.
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  • 16
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    Communications in mathematical physics 25 (1972), S. 190-232 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We investigate the general monomer-dimer partition function,P(x), which is a polynomial in the monomer activity,x, with coefficients depending on the dimer activities. Our main result is thatP(x) has its zeros on the imaginary axis when the dimer activities are nonnegative. Therefore, no monomer-dimer system can have a phase transition as a function of monomer density except, possibly, when the monomer density is minimal (i.e.x=0). Elaborating on this theme we prove the existence and analyticity of correlation functions (away fromx=0) in the thermodynamic limit. Among other things we obtain bounds on the compressibility and derive a new variable in which to make an expansion of the free energy that converges down to the minimal monomer density. We also relate the monomer-dimer problem to the Heisenberg and Ising models of a magnet and derive Christoffell-Darboux formulas for the monomer-dimer and Ising model partition functions. This casts the Ising model in a new light and provides an alternative proof of the Lee-Yang circle theorem. We also derive joint complex analyticity domains in the monomer and dimer activities. Our considerations are independent of geometry and hence are valid for any dimensionality.
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  • 17
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract A necessary and sufficient continuity condition is obtained in order that a topological group of automorphisms of a semi-finite von Neumann algebra in standard form is unitarily implemented. The methods used are extended to the study of unitary implementation for a general von Neumann algebra of those automorphism groups that commute with the one-parameter modular automorphism group.
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  • 18
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract Dispersion relations for the vertex function are derived which are valid when two of the scalar variables are arbitrary complex inside certain domains of the product of the complex planes and the third scalar variable is evaluated just below or just above the physical region-cut. The domains of validity of the dispersion relations for the complex variables are domains with three real dimensions and can be described as neighbourhoods of the boundaries of the “axiomatic” analyticity region of Källén and Wightman. The discontinuity of the vertex function across the cut-surface in the third variable for such values of the remaining variables is expressed only in terms of the dynamical on-mass-shell matrix elements of the locally commuting field operators.
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  • 19
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We show that for an Ising spin system of arbitrary spin with a ferromagnetic pair interaction and a “periodic” external magnetic field there is a unique equilibrium state if and only if the magnetization is continuous with respect to a uniform change in the external field. Hence, if the critical temperatureT c is defined as the temperature where the spontaneous magnetization (which is a non-increasing function of the temperature) becomes positive, then the equilibrium state is unique forT〉T c and is non-unique forT〈T c (when the external field is zero). This implies that the correlation functions have a cluster property forT〉T c . We also show that for an anti-ferromagnet consisting of two sublattices there is a unique equilibrium state if and only if the staggered magnetization is continuous with respect to a change in the staggered field.
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  • 20
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    Communications in mathematical physics 25 (1972), S. 336-336 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
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  • 21
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract Representation formulas for the vertex function are derived which are valid for arbitrary complex values of two of the scalar variables inside the corresponding domain of holomorphy, while the third variable is evaluated in a neighbourhood of positive real values (the corresponding physical-region singularities). The analyticity domains always include at least the corresponding “axiomatic” Källén-Wightman domain. Two alternative versions are given. In the first formula the occurring weight functions are the boundary values of the vertex function along the real axes of the scalar variables. The values of the arguments are such that the boundary values can be expressed in terms of the causal respectively time-ordered functions, which in a well-known way via reduction technique are related to the different form factors of the underlying field theory. In the second formula the weight functions are just the on-mass-shell matrix elements of the field operators which completely describe the dynamics of the theory and e.g. contain explicit information (in their support properties) on the mass spectrum of the field theory. The assumptions behind the results are the very general physical assumptions of Källén and Wightman, i.e. essentially Lorentz-covariance, translation-invariance, “reasonable” mass- and energy-spectrum, and local commutativity. We further need some moderate integrability- and boundedness-properties of the vertex function. It is shown that the formalism can be extended to cover all cases of at most polynomial increase of the vertex function in asymptotic directions inside the Källén-Wightman holomorphy domain. The kernel functions in the representation formulas can be explicitly seen to result in possible singularities only along the physical-region-cuts, i.e. from the contributions of the corresponding physical states, as well as along the more complicated Källén-Wightman boundary-surfaces of the holomorphy domain, which correspond to the so-called “anomalous cuts”. The kernel functions in the second version above the closely connected to simple perturbation theoretical functions.
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  • 22
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    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract The Bogoliubov inequalities are derived for the infinite volume states describing the thermodynamic limits of physical systems. The only property of the states required is that they satisfy the Kubo-Martin-Schwinger boundary condition.
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  • 23
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    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract A class of one-dimensional classical lattice gas models with translationally invariant, stable and strongly tempered many-body interactions, is constructed for which the limiting thermodynamic pressure is a discontinuous function of the density (at fixed temperature). This demonstrates that an apparently “mild” restriction on the potential (“supersummability”) employed by Griffiths and Ruelle in proving the continuity of the pressure in lattice systems, plays, in fact, a crucial role.
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  • 24
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    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We construct a new realization of lightlike particle states. The realization considered corresponds to objects which form partially localized wave packets in the space dimensions transverse to the direction of the lightlike momentum. The states of the transverse motion are classified by the representations of an algebraSU(1, 1) constructed of the generators of the conformal group. It is conjectured that this realization is suitable for the formulation of the “parton”-model of hadrons.
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  • 25
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract For gravitational fields with metrics which admit of groups of motions multiply — transitive on 2-dimensional space-like invariant varieties, the exact solutions of the Einstein gravitational equations are given for the case when the sources of the gravitational field are dust-like matter and a magnetic field. A magnetic field is orientated along a direction orthogonal to transitivity hypersurface. The solutions contain arbitrary functions. In the case of transitivity hypersurface of positive curvature and in the absence of a magnetic field, the solution is reduced to the Tolman spherically symmetric solution for dust-like matter. The conditions are studied under which the solutions with a magnetic field become asymptotically isotropic and approach the flat and the open Friedmann models. The case of transitivity hypersurfaces with signature (+ −) is also considered.
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  • 26
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    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract A Lorentz cobordism between two (in general nondiffeomorphic) 3-manifoldsM 0,M 1 is a pair (M,v), whereM is a differentiable 4-manifold andv is a differentiable vector field onM, such that 1) the boundary ofM is the disjoint union ofM 0 andM 1, 2)v is everywhere nonzero, 3)v is interior normal onM 0 and exterior normal onM 1. Such a manifoldM admits a Lorentz tensor with respect to whichM 0 andM 1 are spacelike hypersurfaces; thus a Lorentz cobordism is a model of a portion of a spacetime in which “the topology of spacelike hypersurfaces is changing”. We discuss the form that these changes can take, and give two methods for constructing a Lorentz cobordism between two nondiffeomorphic 3-manifolds. We comment on the possible relevance of Lorentz cobordism to the problem of gravitational collapse.
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  • 27
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract In Ref. [1] the axiomatic foundation of the Hilbert space structure of quantum mechanics was outlined. Apart from a set of physically plausible axioms, the (mathematical) assumption (V 1) of the minimal-decomposition property of the basenorm spaceB was incorporated into the axiomatic scheme of the theory. It is shown in the present paper that the assumption (V 1) is superfluous. In the first part of the paper we give a short summary of the axioms; in the second part the main theorems are proved without using assumption (V 1).
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  • 28
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We examine field theories with a compact groupG of exact internal gauge symmetries so that the superselection sectors are labelled by the inequivalent irreducible representations ofG. A particle in one of these sectors obeys a parastatistics of orderd if and only if the corresponding representation ofG isd-dimensional. The correspondence between representations of the observable algebra and representations ofG extends to a mapping of the intertwining operators for these representations preserving linearity, tensor products and conjugation. Although we assume no explicit commutation property between fields, the commutation relations of fields of the same irreducible tensor character underG at spacelike separations are largely determined by the statistics parameter of the corresponding sector. For fields of conjugate irreducible tensor character the observable part of the commutator (anticommutator) vanishes at spacelike separations if the corresponding sector has para-Bose (para-Fermi) statistics.
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  • 29
    ISSN: 1432-0916
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    Notes: Abstract Using error-affected data for the scattering amplitude on a part of the cuts, we construct a stable extrapolation procedure for it to the remaining parts of the cuts (higher energies or crossed reactions), using Carleman-weighted dispersion relations. To this end, it is assumed that the amplitude satisfies on the cut some smoothness condition of the Hölder type.
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  • 30
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    Communications in mathematical physics 26 (1972), S. 247-258 
    ISSN: 1432-0916
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    Notes: Abstract We study some properties of invariant states on aC*-algebraA with a groupG of automorphisms. Using the concept ofG-factorial state, which is a “non-commutative” generalization of the concept of ergodic measure, in general wider in scope thanG-ergodic state, we show that under a certain abelianity condition on (A,G), which in particular holds for the quasi-local algebras used in statistical mechanics, two differentG-ergodic states are disjoint. We also define the concept ofG-factorial linear functional, and show that under the same abelianity condition such a functional is proportional to aG-ergodic state. This generalizes an earlier result for complex ergodic measures.
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  • 31
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    Communications in mathematical physics 26 (1972), S. 271-275 
    ISSN: 1432-0916
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    Notes: Abstract An approach to quantization of general relatively using a reformulation of the classical theory in which the events of space-time play essentially no role is discussed.
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  • 32
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    Communications in mathematical physics 26 (1972), S. 259-270 
    ISSN: 1432-0916
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    Topics: Mathematics , Physics
    Notes: Abstract The stability of a class of homogeneous cosmological models is investigated. It is shown that the perturbation problem for six such universes can be reduced to a system of ordinary differential equations. The time development of the perturbations is such that they remain finite at all times for which the unperturbed metric is non-singular.
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  • 33
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    Communications in mathematical physics 26 (1972), S. 276-279 
    ISSN: 1432-0916
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    Notes: Abstract Under conditions which are sufficiently general for physical applications the trace inequalities $$tr e^{ - (A + B)} \leqq tr e^{ - A} e^{ - B} $$ and $$|tr e^{ - (A + iB)} | \leqq tr e^{ - A} $$ withA andB self adjoint are shown in a rigorous manner.
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  • 34
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    Communications in mathematical physics 26 (1972), S. 280-289 
    ISSN: 1432-0916
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    Notes: Abstract A number of useful inequalities, which are known for the trace on a separable Hilbert space, are extended to traces on von Neumann algebras. In particular, we prove the Golden rule, Hölder inequality, and some convexity statements.
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  • 35
    ISSN: 1432-0916
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    Notes: Abstract A Kerr-Schild type ansatz for thef andg tensor fields leads to a tractable form of the field equations of Salam's two-tensor theory of gravity in vacuo. While the general solution contains the Schwarzschild and Kerr metrics in the pure Einstein vacuum case, we can show in thef-g case that all “non-trivial” (f≠g) solutions are restricted to have the form of “plane-fronted waves”.
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  • 36
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    Notes: Abstract In this paper we intend to analyze the geometry underlying the various representations of the relativistic scattering amplitudes. More precisely we consider the direct-channel expansion, its euclidean contraction and the crossed-channel representation. In all these representations one can distinguish the factors which express the dynamics from those which reflect the symmetry; starting from the latter, one can try a geometrical interpretation of the harmonic analysis of the scattering amplitude on the Poincaré group.
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  • 37
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    Notes: Abstract The vacuum line element inside an infinitely long rotating hollow cylinder is the usual flat space line element. It is fitted in a most general way to the general cylindrical vacuum field outside at the singular hypersurfaceR 0=const, representing the infinitely thin hollow cylinder. With the use of the jump conditions atR 0=const the surface densities τ μ ν , of which the energy-momentum-stress tensor τ μ ν of the shell consists, are calculated. The physical properties of the cylinder, as derived from the eigenvalues and -vectors of τ μ ν , and the generated gravitational field are discussed in full detail.
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  • 38
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    Communications in mathematical physics 26 (1972), S. 321-332 
    ISSN: 1432-0916
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    Notes: Abstract Within the framework of general relativity the Dirac equation for the hydrogen atom is given in case of a spatially isotropic and homogeneous expanding space-time (Robertson Walker metric). In the special case of the static, closed 3-dimensional spherical space (Einstein Universe) we get a continuous energy spectrum for the H-atom.
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  • 39
    ISSN: 1432-0916
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    Notes: Abstract We give an integrability criterion for Lie algebra representations in a reflexive Banach space. Applications are given to skewsymmetric Lie algebra representations in Hilbert spaces and to essential skewadjointness of a sum of two skewadjoint operators.
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  • 40
    ISSN: 1432-0916
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    Notes: Abstract A systematic presentation of the quasi-linear first order symmetric hyperbolic systems of Friedrichs is presented. A number of sharp regularity and smoothness properties of the solutions are obtained. The present paper is devoted to the case ofR n with suitable asymptotic conditions imposed. As an example, we apply this theory to give new proofs of the existence and uniqueness theorems for the Einstein equations in general relativity, due to Choquet-Bruhat and Lichnerowicz. These new proofs usingfirst order techniques are considerably simplier than the classical proofs based onsecond order techniques. Our existence results are as sharp as had been previously known, and our uniqueness results improve by one degree of differentiability those previously existing in the literature.
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  • 41
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    Notes: Abstract Feynman's integral is defined with respect to a pseudomeasure on the space of paths: for instance, letC be the space of pathsq:T⊂ℝ → configuration space of the system, letC be the topological dual ofC; then Feynman's integral for a particle of massm in a potentialV can be written where $$S_{\operatorname{int} } (q) = \mathop \smallint \limits_T V(q(t)) dt$$ and wheredw is a pseudomeasure whose Fourier transform is defined by for μ∈C′. Pseudomeasures are discussed; several integrals with respect to pseudomeasures are computed.
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  • 42
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    Notes: Abstract We give a rigorous treatment in the infinite volume limit of a model Hamiltonian representing an imperfect Boson gas. In particular we obtain the exact expression for the mean particle density in the infinite volume limit as a function of the chemical potential, and show that the density function has a singularity at the critical density for Bose-Einstein condensation. We prove that, unlike the ideal Boson gas, the imperfect Boson gas has the same behaviour in the infinite volume limit for the grand canonical ensemble as for the canonical ensemble, and is moreover stable under small perturbations. We finally exhibit the possibility of ordinary condensation and prove that a system in an intermediate situation between two pure phases consists of a simple mixture of the two phases involved.
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  • 43
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    Communications in mathematical physics 28 (1972), S. 109-122 
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    Notes: Abstract This paper investigates mathematical properties of a finite-dimensional real algebra of linear operators which are generated by an orthomodular lattice of filters in the sense of Mielnik [4]. Properties of filter decomposability and a representation theorem for the vector space underlying the algebra mentioned are derived.
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  • 44
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract This paper states two equivalent conditions from which modularity of the latticeG of decision effectsE can be derived. It may be seen as a supplement to Ludwig's approach [5] to an axiomatic foundation of physical theories. As a consequence of these conditions every filterT E is a self-adjoint projector on the Hilber spaceB′ generated by the decision effects.
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  • 45
    ISSN: 1432-1041
    Keywords: Beta-receptor blocking agents ; asthma bronchiale ; bronchoconstriction ; airway resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Summary It was shown by body plethysmography that even in predisposed patients Doberol® in therapeutical doses up to 50.0 mg administered orally had apparently no bronchoconstrictive effect, pointing to a relative cardioselectivity of the drug. Therefore, in the presence of bronchial asthma the use of Doberol® may not be contraindicated.
    Notes: Zusammenfassung Doberol® ist, in therapeutischer Dosierung bis zu 50.0 mg bei oraler Medikation mit hoher Wahrscheinlichkeit auch bei prädisponierten Patienten ohne bronchokonstriktorische Wirkung. Es weist somit eine relative Kardioselektivität auf. Das Asthma bronchiale stellt demnach allenfalls eine relative Kontraindikation für Doberol® dar.
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  • 46
    ISSN: 1432-1041
    Keywords: Amobarbital ; pentobarbital ; barbiturates ; gas chromatography ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Gas chromatographic methods are described for the assay of amobarbital and pentobarbital in 500 µl samples of plasma, in concentrations down to 250 ng/ml. After ether extraction at pH 5.5, the barbiturates are reextracted into an alkaline solution of trimethylanilinium hydroxide and are determined quantitatively by gas chromatography as their dimethylated derivatives. The method has been used successfully in volunteers receiving therapeutic doses of these bariturates.
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  • 47
    ISSN: 1432-1041
    Keywords: Antihypertensive agents ; clonidine ; methyldopa ; hypertensive rebound ; side effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The results of a titrated-dose cross-over comparison of clonidine with methyldopa are reported. Only one third of those entering the trial completed it. The blood pressure lowering effect of the two drugs is seen to be very similar. Patients experienced significantly more dry mouth whilst on clonidine but sedation was equally distributed over the two treatments. A hypertensive rebound occurred in some patients after sudden withdrawal of clonidine. The place of this new compound in routine management of hypertension is discussed.
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  • 48
    ISSN: 1432-1041
    Keywords: Hexapropyamate ; sleep ; hypnotics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of an ordinary clinical dose (400 mg) of hexapropymate (Mordirax®) on sleep were investigated in 16 young healthy volunteers by a polygraphic technique. Each subject was studied for two nights with the drug and for two reference nights with a placebo. The polygraphic recordings of EEG, neck EMG, oculogram and ECG were classified in different sleep stages and were scored according to international norms. — There were limited changes of sleep pattern during hexapropymate. REM sleep amounted to 22.1% for nights with placebo, and 19.8% for nights with hexapropymate; this difference is statistically significant at the 5 per cent level. A corresponding increase of Stage II sleep was found during hexapropymate nights (p〈0.02). The drug caused an increase in REM-latency (p〈0.05); the number of REM periods was unchanged. — The drug was shown to have hypnotic effects in this group of subjects all of whom were very good sleepers: total sleep time increased slightly, the sleep latency decreased and so did the number of nocturnal awakenings (p〈0.002). — A digit-span-forward test, as well as the subject's own self ratings did not demonstrate any hang-over effects.
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  • 49
    ISSN: 1432-1041
    Keywords: Sulphamethoxazole ; trimethoprim ; pharmacokinetics ; uraemia ; sulphonamides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of sulphamethoxazole (SMZ) and trimethoprim (TMP) have been investigated in four healthy volunteers, 15 patients with stable chronic renal failure and 3 patients on regular dialysis. The dosage schedule was 400 mg of SMZ and 80 mg of TMP orally every 12 h. The plasma concentrations and urinary excretion have been analysed in terms of a one compartment open model, allowing for elimination by renal excretion and metabolic processes. — At equilibrium the plasma concentrations of unchanged sulphonamide showed no significant correlation with the degree of renal impairment. The accumulation of TMP increased slightly without affecting the concentration ratio of both agents in plasma. In contrast, increasing accumulation of metabolized SMZ was demonstrated in the presence of renal insufficiency. Indirect evidence indicates that rising metabolite levels under these circumstances may lead to a displacement of unchanged sulphonamide from protein binding sites. — The cumulative urinary excretion amounted to 82.4% of the dose of sulphonamide administered, which probably corresponds to the fraction of the compound absorbed. The urinary concentration of biologically active SMZ was slightly below the plasma level, especially in advanced renal failure, but it remained above the minimum inhibitory concentrations reported in the literature. The concentration of TMP in urine was considerably higher than in plasma, it decreased with loss of renal function as did active SMZ.
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  • 50
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 82 (1972), S. 265-279 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Antiseren gegen die Thylakoide aus Rhodopseudomonas spheroides pr\:acipitieren die isolierten Thylakoide. Sie geben im Ouchterlony-Test eine gef\:arbte Bande. Nach Ultraschallbehandlung treten drei weitere farblose Banden auf. Die gel\:osten Membranproteine der Thylakoide werden von Anti-Thylakoid-Serum pr\:acipitiert. Im Ouchterlonytest geben sie zwei Banden, wovon eine mit der gef\:arbten Thylakoidbande identisch ist. Antiserum gegen dieses Pr\:aparat zeigt im homologen System f\:unf Banden. Es pr\:acipitiert die Thylakoide und gibt im Geltest wenigstens vier Banden mit Thylakoiden. Da nur Antigendeterminanten der Oberfläche einer Partikel mit Antikörpern reagieren können, müssen kreuzreagierende Determinanten der Proteine an der Oberfläche der Membran lokalisiert sein. 2. Antiseren gegen Cytoplasmaproteine pr\:acipitieren die frischen Thylakoide nicht. Durch Ultraschallbehandlung werden Substanzen freigesetzt, die sowohl von Anti-Thylakoid-Serum als auch von Cytoplasma-Antiserum gef\:allt werden. Sie geben im Ouchterlonytest mit beiden Antiseren 3\2-4 farblose Banden. Sie sind identisch mit drei Banden, die durch Anti-Cytoplasma-Serum in der Cytoplasma-fraktion angezeigt werden. In der homologen Reaktion von Cytoplasma-Antiserum mit den Cytoplasmaproteinen sind 6\2-7 farblose Banden nachweisbar. Es wird angenommen, daß die löslichen Komponenten, die durch Ultraschall-behandlung freigesetzt werden, aus dem Innern der Thylakoide stammen. 3. Der Kohlenhydratgehalt betr\:agt in den Thylakoiden 3,6\2-4,0%, in der Cytoplasmafraktion 1,4%. Im Hydrolysat wurden Arabinose, Glucose und Galaktose nachgewiesen. Es konnte durch Perjodatabbau gezeigt werden, da\sB Kohlenhydrate am Antigenaufbau beteiligt sind. Einige Immunbanden konnten als Glykoproteine charakterisiert werden. 4. Antiseren gegen Lipide pr\:acipitieren die Thylakoide nicht, doch werden die Antik\:orper spezifisch absorbiert, wie durch Commbs-Teste gezeigt werden konnte. Da ein partieller Abbau der Membranproteine durch Proteasen eine direkte Pr\:acipitation der Thylakoide durch die Lipid-Antik\:orper bewirkte, liegen die Lipid-determinanten in einer tieferen Schicht der Membran. 5. Ein Antiserum gegen die Thylakoide von Oscillatoria chalybea pr\:acipitiert zwar die Oscillatoria-Thylakoide. Im Ouchterlonytest diffundieren die Thylakoide nicht. Durch Behandlung mit Ultraschall werden, wie bei Thylakoiden aus Purpurbakterien, Komponenten freigesetzt, die im Ouchterlonytest drei Banden geben. Auch die nachgewaschenen Ultraschallfragmente der Thylakoide diffundieren nicht in das Gel hinein, doch werden sie im Objekttr\:agertest von Antiserum gegen die Thylakoide bzw. gegen das Lamellarsystem der Chloroplasten h\:oherer Pflanzen pr\:acipitiert. Dies Antiserum enthält also Antikörper gegen drei artspezifische gelöste und gegen wenigstens eine partikelgebundene Antigendeterminante. 6. Zur Ermittlung der Spezifit\:at der Rhodopseudomonas spheroides-Antiseren wurden Kreuzreaktionen mit Thylakoiden und Cytoplasmafraktionen aus sechzehn Bakterienspecies vorgenommen. Die serologischen Eigenschaften der Bakterienthylakoide zeigen eine gr\:o\sBere Vielfalt als die Thylakoide aus Chloroplasten.
    Notes: Summary 1. Antisera to thylakoids of Rhodopseudomonas spheroides precipitate isolated thylakoids. They show one pigmented precipitation line in the Ouchterlonytest. After ultrasonication, three additional colourless bands result. The dissolved membrane proteins of thylakoids are precipitated by antisera to thylakoids. They show two colourless lines in the Ouchterlony-test, one of which is identical with the pigmented thylakoid-band. Antiserum to the membrane proteins shows five bands in the homologous system. It precipitates thylakoids and shows at least four lines with thylakoids in the gel test. Because only antigen determinants of the surface of a particle can react with antibodies, crossreacting determinants of proteins must be localized in the outer surface of the thylakoid membrane. 2. Antisera to cytoplasmic proteins do not precipitate freshly-prepared thylakoids. Substances liberated by ultrasonication react with antiserum to thylakoids and antiserum to cytoplasm. In the gel test four colourless lines arise with both antisera. These are identical with three lines produced in the reaction of antiserum to cytoplasm with the cytoplasm fraction. In the homologous reaction of cytoplasm antiserum with cytoplasm proteins, six to seven colourless lines are to be seen. It is suggested that the origin of these compounds, freed by ultrasonication, is the lumen of the thylakoids. 3. The carbohydrate content of thylakoids is 3.6–4.0%, and of cytoplasm fraction 1.4%. Arabinose, glucose and galactose are present in a thylakoid hydrolysate. The participation of carbohydrates in antigen composition has been demonstrated by degradation with periodate. Several immunobands could be characterized as glycoproteins. 4. Antisera to lipids do not precipitate thylakoids directly nevertheless antibodies are specifically adsorbed, as demonstrated by the Coombs-tests. After partial degradation of membrane proteins by proteases the thylakoids are precipitated directly. Therefore lipid determinants are situated in a deeper layer of the membrane. 5. An antiserum to thylakoids of Oscillatoria chalybea precipitate Oscillatoria-thylakoids. These thylakoids do not diffuse in agarose gel. As with the thylakoids of purple bacteria, substances will be freed by ultrasonication, which show three lines in the Ouchterlony-test. Further fragments of sonicated thylakoids do not diffuse in gel, but are precipitated in the slide-test by antisera to thylakoids and to the lamellar system of chloroplasts from higher plants. Thus, this antiserum contains antibodies to three species-specific soluble compounds and against at least one particlebound antigen determinant. 6. Investigation into the specificity of the antisera to Rhodopseudomonas spheroides-thylakoids were made by crossreactions with thylakoids and cytoplasm fraction from sixteen bacteria. The immunological properties of bacterial thylakoids show a greater diversity than thylakoids from chloroplasts.
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  • 51
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several cell-wall and membrane affecting agents were tested for causing release of periplasmic proteins of E. coli B as compared by gel electrophoresis. Osmotic shock and polymyxin-treatment yielded the best differentiated protein patterns. The periplasmic proteins derived from different E. coli strains and other gram-negative bacteria by polymyxin-treatment were compared. Whereas related strains showed similarities in the protein positions, unrelated gram-negative bacteria showed great differences of the protein bands. The polymyxin-induced liberation of periplasmic proteins was dependent upon the growth phase and growth media of the bacteria and was severely inhibited by 10-2 M magnesium chloride.
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  • 52
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A few days before vintage, yeasts were isolated quantitatively from three varieties of wine grape from three châteaux of the Graves region of the Gironde. There were about 105 viable yeasts/g of grape, from which only Kloeckera apiculata, Metschnikowia pulcherrima and one or more species of Rhodotorula were isolated.
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  • 53
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 83 (1972), S. 63-70 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A double-layer agar method was developed for screening microorganisms producing protease inhibitors. After colonies were grown on skim-milk agar, an agar containing sterile protease was poured onto the bottom layer. After incubation the skim-milk agar turned transparent except around colonies producing protease inhibitors. The frequency of such organisms in samples of soil, manure, and hay was studied. 27 of more than 10 000 colonies showed a significant protease-inhibiting capacity. One organism with a high trypsin-inhibiting capacity was identified as Streptomyces violascens (Preobrazhenskaya and Sveshnikova) Pridham et al. and selected for further studies.
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  • 54
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 83 (1972), S. 71-77 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Production of protease inhibitors from Streptomyces violascens U 10 600 was studied in quiescent flasks, shake flasks, and fermentors. A starting pH in the medium between pH 6 and 7 was the most favourable for the process. Both trypsin and chymotrypsin inhibitors were produced. Maximum inhibitor activity was attained after 3 days of cultivation in a protein powder medium at 18°C with pH control to pH 5 during the latter part of the process.
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  • 55
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Das Membransystem von Rps. capsulata setzt sich aus Cytoplasmamembran und intracytoplasmatischen Membranen zusammen. In anaeroben Lichtzellen und in Dunkelzellen unter geringen Sauerstoffpartialdrucken bestehen die intracytoplasmatischen Membranen aus Vesikeln, bei Anzucht unter hohen Sauerstoffspannungen sind sie tubulär. Auch nach einer 8stündigen Kultur bei 400 mm (Hg) Sauerstoffpartialdruck, d.h. unter Bedingungen, die eine BChl-Synthese vollständig hemmen, enthalten die Zellen noch intracytoplasmatische Tubuli an einem Zellpol. Nach Zellaufschluß mit der French pressure cell gelang es durch anschließende fraktionierte Zentrifugation und Reinigung der Partialfraktionen über Ficoll-Gradienten 3 membranhaltige Banden zu isolieren. Die leichte Bande besteht vorwiegend aus Membranfragmenten der Cytoplasmamembran. Die mittlere Bande enthält die intracytoplasmatischen Tubuli aerob angezogener Zellen. Die schwere Bande, die den höchsten Reinheitsgrad aufweist, setzt sich aus den intracytoplasmatischen Vesikeln der Licht-bzw. der semiaeroben Dunkelzellen zusammen. 14C-Markierungsexperimente und elektronenmikroskopische Beobachtungen sprechen für morphologische und morphogenetische Zusammenhänge zwischen den Membranfraktionen und stützen damit die Hypothese, daß alle Membrantypen in einer Zelle Teile eines zusammenhängenden Membransystems sind. Die einzelnen Membrantypen können reversibel ineinander überführt werden.
    Notes: Summary The membrane system of Rhodopseudomonas capsulata, strain 37b4 is investigated in cells cultivated anaerobically in the light and in the dark, respectively, at different oxygen partial pressures (pO2). The intracytoplasmic membrane vesicles of anaerobically light grown and semiaerobically [5 mm (Hg) pO2] dark grown cells show similar diameters (30–50 nm). Growing aerobically in darkness the cells contain tubular intracytoplasmic membranes with comparable diameters. An increase of the pO2 up to 400 mm (Hg) results in a slightly decreased growth rate and in a complete inhibition of bacteriochlorophyll synthesis and intracytoplasmic membrane formation. After 8 h of cultivation under these conditions tubular membranes are still found. However, they are restricted to one cell pole only. In order to isolate the membranes, cells were broken by means of a French pressure cell. The crude, membrane fractions (sedimented at 104000-314000xg, 60 min) are purified by centrifugation on a Ficoll density gradient. This results in the formation of three membrane fractions. The light fraction consists of small vesicular particles derived from the cytoplasmic membrane. Crude membrane fractions of all cells sedimented at 314 000xg contain a relative high percentage of these particles. Intracytoplasmic membranes of aerobically grown cells are found in a middle band. Their tubular structure remains unaffected if the cells are treated by lower pressures during homogenization. The heavy band contains the intracytoplasmic membrane vesicles from light grown and from semiaerobically dark grown cells in a highly purified form. After treatment with butanol or NaCl and subsequently with lysozyme plus EDTA cells release flat membrane fragments which still exhibit invaginations. This shows once more that the membranes are connected to each other. Pulse chase experiments with (2-14C)-acetate support the hypothesis that the cytoplasmic membrane and intracytoplasmic membranes are transformable into each other. So they should be looked at as a morphogenetical unit.
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  • 56
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 85 (1972), S. 239-248 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Nonactinsäure und Homononactinsäure, die bisher nicht als freie Stoffwechselprodukte bekannt waren, wurden aus Kulturlösungen von Streptomyces griseus isoliert. Beide Hydroxysäuren wurden als Methylester gereinigt und chromatographisch und spektroskopisch identifiziert. Die optischen Drehwerte zeigen, daß die Nonactinsäure überwiegend als (-)-Isomer, Homononactinsäure dagegen praktisch einheitlich als (+)-Isomer vorliegt. In produzierenden Kulturen konnten die freien Nonactinsäuren bereits vor Beginn der Makrotetrolidsynthese nachgewiesen werden. (+,-)-Nonactinsäure-8-3H wurde synthetisiert und mit Kulturen von Streptomyces griseus und Streptomyces griseoflavus inkubiert; 6 bis 52% der markierten Verbindung wurden in die Makrotetrolide eingebaut. Die Spezifität des Einbaus wurde durch chemischen Abbau bewiesen. Die Ergebnisse zeigen, daß die chiralen Hydroxysäuren direkte Vorstufen der Makrotetrolide sind.
    Notes: Summary Nonacting and homononactinic acid which were not previously known as free metabolic products, were isolated from culture broths of a macrotetrolide producing strain of Streptomyces griseus. Both hydroxy acids were purified and identified as their methyl esters by chromatographic and spectroscopic methods. The optical rotation values indicated that the free nonactinic acid is mainly the (-)-isomer whereas homononactinic acid appears to be pure (+)-isomer. In producing cultures the nonactinic acids could be detected prior to the beginning of macrotetrolide synthesis. (+,-)-Nonactinic acid-8-3H was synthesized and incubated with cultures of Streptomyces griseus and Streptomyces griseoflavus (the latter producing mainly monactin and dinactin); between 6 and 52% of the labeled acid were incorporated into the macrotetrolides. Chemical degradation showed that no randomization of tritium had occurred. The results suggest that the chiral hydroxy acids are direct biosynthetic precursors of the macrotetrolides.
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  • 57
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Es wurden 30 spontane Mutanten von Bacillus subtilis isoliert, die gegen Ketomycin (3-Cyclohexenylglyoxylsäure), einen Isoleucin-Antagonisten, resistent sind. Diese Mutanten konnten in 3 Gruppen unterteilt werden: starke Isoleucin-Ausscheider (11–34 μg Isoleucine/ml Kulturflüssigkeit), schwache Ausscheider (2 μg/ml) und Nichtausscheider. Nur die starken Ausscheider (Gruppe 1) besitzen eine durch Isoleucin nicht hemmbare Threonin-Desaminase. Mutanten mit dereprimierter Synthese von Threonin-Desaminase wurden nicht gefunden. Nicht-ausscheider sind nicht resistent auf Grund einer fehlenden Umwandlung von Ketomycin in Cyclohexenylglycin. Unter diesen 30 Mutanten wurden 2 ungewöhnliche Mutanten gefunden. Die eine Mutante, ein starker Ausscheider, besitzt eine instabile Threonin-Desaminase. Die andere Mutante, ein Nichtausscheider, besitzt eine Threonin-Desaminase mit einer sigmoiden Substratsättigungskurve. Dies steht im Gegensatz zum Wildtyp-Enzym, welches eine hyperbolische Kurve besitzt.
    Notes: Summary Thirty spontaneous mutants of Bacillus subtilis resistant to Ketomycin (3-cyclohexenylglyoxylic acid), an isoleucine antagonist, were isolated. These mutants could be subdivided into 3 groups: strong isoleucine-excretors (isoleucine accumulation in the culture fluid: 11–34 μg/ml), weak excretors (2 μg/ml), and nonexcretors. Only the strong excretors (group 1) possess an isoleucine insensitive threonine deaminase. Mutants with derepressed synthesis of threonine deaminase were not found. The resistance of nonexcretors is not due to a lack of conversion of ketomycin to cyclohexenylglycine. Within these 30 mutants, two unusual mutants were found. One mutant (strong excretor) has an unstable threonine deaminase. The other mutant (nonexcretor) possesses a threonine deaminase showing a sigmoid substrate saturation curve in contrast to the wild type enzyme, which shows a hyperbolic curve.
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  • 58
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Acetylene was reduced to ethylene by effective white clover nodules and by fully and partially effective intact nodules, nodule homogenates, and bacteroids of soybeans. Succinate and several amino acids markedly stimulated the reduction by effective soybean bacteroids, but the stimulation was slight with partially effective bacteroids. Acetylene metabolism by effective soybean bacteroids was also enhanced by excretions of in vitro-grown Rhizobium japonicum, excretions of bacteria derived from effective and ineffective nodules, and the soluble fraction from these nodules. Inhibitors of nitrogen fixation were not found in ineffective nodules. Ineffective soybean and white clover nodules and homogenates or isolated bacteria from ineffective soybean nodules did not reduce acetylene. Additions of succinate, amino acids, the soluble fraction of effective nodules, or excretions of effective bacteroids or of in vitro-grown cells of an effective R. japonicum strain did not promote nitrogen fixation by bacterial cells obtained from ineffective soybean nodules.
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  • 59
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Catabolic effects which exert control over the inducible synthesis of three enzymes in Arthrobacter crystallopoietes involve at least three different mechanisms: interference with inducer transport, severe catabolite repression, and transient repression. The rate of histidase induction by histidine is reduced by incubation of the cells with succinate or glucose. The maximum effect of succinate, 67% reduction in histidase production, occurs only after 100 min of incubation with succinate. At least 3h of incubation are required for the maximum effect of glucose (31% reduction in enzyme induction). Both succinate and glucose inhibit histidine transport. Cyclic adenosine 3′,5′-monophosphate (cyclic AMP), at 10-7 M, slightly stimulates the induction of histidase in cultures both with or without succinate. No conditions were found in which cyclic AMP abolishes the effect of succinate. Induction of l-serine dehydratase by glycine is severely and permanently repressed by glucose and to a lesser extent by citrate. Glucose does not affect glycine uptake. Succinate, fumarate, and aspartate, which are all better substrates than glucose or citrate for growth of A. crystallopoietes, have no effect on l-serine dehydratase induction. Induction and repression of l-serine dehydratase are not affected by cyclic AMP. Synthesis of isocitrate lyase after addition of acetate is unaffected by glucose but is severely repressed by succinate or fumarate. Aspartate and glutamate cause a transient repression of enzyme synthesis after which synthesis proceeds at the control rate. The ability to transport acetate is inducible. Development of this capacity in the presence of acetate is not affected by succinate or glutamate. Cyclic AMP has no effect on enzyme production or repression. A. crystallopoietes takes up radioactive cyclic AMP and has at least one of the enzymes of cyclic AMP metabolism, adenyl cyclase.
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  • 60
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Phenethyl alcohol (PEA) at concentrations ranging from 0.04 to 0.08% (v/v) repressed conidial differentiation (C) and its associated carotenogenesis in wild type neurospora crassa. With 0.16–0.32%, most of the conidia germinate into swollen, yeast-like cells (Y) producing buds instead of mycelial filaments (M). Incubation with PEA increased alcoholic fermentation and sharply reduced the immunoelectrophoretic diagram. The step-wise reduction of Neurospora morphogenesis (C→M→Y) reveals the trimorphic potentiality of its hyphal system.
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  • 61
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Ruhende Zellen von Rhodospirillum rubrum formten in Gegenwart von Substrat nach 1–4 Tagen ihre intracytoplasmatischen Vesikel zu Schläuchen und unregelmäßigen Membran-Aggregaten um. Die Veränderungen traten anaerob und aerob im Licht sowie in aerober Dunkelkultur auf und waren von der Art des Substrats abhängig. Ohne Substratzugabe waren keine Veränderungen im intracytoplasmatischen Membransystem zu beobachten. Auch bei einer völligen Umgestaltung der Thylakoidvesikel blieb der Bacteriochlorophyllgehalt der Zellen nahezu konstant. Da in denselben Zellen sich Speicherstoffe anhäuften, kann angenommen werden, daß die ATP-Bildung nicht limitierend war. Die Rate der anaeroben Photophosphorylierung und die O2-Aufnahme im Dunkeln verringerten sich jedoch. Auch die Zahl der vermehrungsfähigen Bakterien nahm ab. Es wird diskutiert, ob die Veränderungen der intracytoplasmatischen Membranvesikel nur eine Desintegration der Membranen beim Absterben der Bakterien sind oder ob sie als eine vom Stoffwechsel der Zelle kontrollierte Morphogenese ablaufen.
    Notes: Summary In resting cells of Rhodospirillum rubrum under N-limitation in presence of a substrate the intracytoplasmic vesicles were transformed within 1 to 4 days into tubes and irregular membrane aggregates. The changes were observed either in the light under aerobic and anaerobic conditions or in the dark under aerobic conditions. They were dependent on the substrate supplied. Without substrate no changes in the intracytoplasmic membrane system occurred. Even after a complete morphological change of the thylakoid vesicles the bacteriochlorophyll content of the cells remained nearly constant. It can be assumed that the ATP production was not limiting, because in the same cells storage material accumulated. On the other hand, however, the rate of the anaerobic photophosphorylation, the O2-consumption in the dark, and the number of viable cells in the culture decreased. It is discussed, whether the variations of the intracytoplasmic membrane vesicles are only a disintegration of the membranes during death of the bacteria or whether they occur as a morphogenesis which is controlled by the metabolism of the cell.
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  • 62
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. At least part of trisporic acid (TA) synthesis in a mated culture of the fungus Blakeslea trispora proceeds by secretion of mating-type-specific precursor molecules by both mating types, and conversion of these molecules to TA by the mating partner. 2. The contribution of the minus strain to TA synthesis is dependent on the amount of plus mycelium present. On the other hand, the contribution of the plus strain is influenced by the biosynthetic activity of the minus mycelium 3. This mutual stimulation of both sexual partners is abolished by 5-fluorouracil.
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  • 63
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Der Sauerstoff-Verbrauch einer Suspension anaerob gewachsener Zellen von E. coli, die 2 Std in einer Caseinhydrolysatlösung belüftet wurde, ist etwa 4–5mal höher als der einer gleichzeitig mit Stickstoff begasten Suspension. Chloramphenicol, Puromycin, Rifampicin, Hydroxylamin und Glucose verhindern die Ausbildung der Atmungsaktivität während der Belüftung, Cycloheximid und Actinomycin D dagegen nicht. Der Hemmeffekt der Glucose kann durch cyclisches Adenosin-3′,5′-monophosphat teilweise aufgehoben werden. Eine belüftete Suspension baut die Porphyrin-Vorstufe 3H-δ-Aminolävulinsäure etwa 4–5 mal stärker ein als eine mit Stickstoff begaste. Die oben genannten Inhibitoren, mit Ausnahme von Cycloheximid und Actinomycin D, hemmen diesen Einbau in unterschiedlich starkem Maße.
    Notes: Summary The oxygen consumption of an anaerobically grown cell suspension of E. coli which has been aerated in a solution of casein hydrolysate for 2 h exceeds by about 4 to 5 times that of a suspension which has been gassed with nitrogen for the same period. Chloramphenicol, puromycin, rifampicin, hydroxylamine, and glucose block the formation of respiratory activity during aeration; cycloheximide and actinomycin D are inactive in blocking. The repressive effect of glucose can partially be relieved by cyclic adenosine-3′, 5′-monophosphate. An aerated suspension incorporates 4 to 5 times more of the porphyrin precursor 3H-δ-aminolevulinic acid than a suspension gassed with nitrogen. The above mentioned inhibitors, with the exception of cycloheximide and actinomycin D, partially repress this incorporation.
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  • 64
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Sarcina lutea ATCC 9341 setzt verschiedene einfache aliphatische Aldehyde zu den entsprechenden Monoaminen um. An Acetonpräparaten wurden einige Eigenschaften des für die Reaktionen verantwortlichen Enzymsystems untersucht. Es handelt sich um eine Aminotransferase, die die Transaminierung zwischen Aminosäuren und Aldehyden katalysiert. 2. Geeignete NH2-Donatoren sind l-Glutaminsäure und in geringerem Maße l-Glutamin und l-Asparaginsäure. NH2-Akzeptoren sind alle Aldehyde der Reihe Äthanal bis Hexanal mit deutlicher Bevorzugung von n-Butanal. 3. Das pH-Optimum der Enzymkatalyse liegt bei pH 8.5–8.7. 4. Eine Abhängigkeit der Reaktion von Pyridoxalphosphat ließ sich nicht nachweisen. Das Alter der Bakterienkultur hat keinen wesentlichen Einfluß auf die Aktivität der Enzympräparate. 5. Die Bedeutung des Enzymsystems für die Biogenese primärer aliphatischer Monoamine bei Bakterien wird diskutiert.
    Notes: Summary 1. Simple aliphatic aldehydes are converted into the corresponding monoamines by Sarcina lutea ATCC 9341. Using acetone-dried cells some properties of the aminating enzyme system were studied. The enzyme was found to be an aminotransferase which catalyzes transamination between amino acids and aldehydes. 2. l-Glutamic acid is most effective as NH2-donator, followed by l-glutamine and l-aspartic acid. All aldehydes of the series ethanal to hexanal as well as 2-methylpropanal and 3-methylbutanal are suitable NH2-acceptors, the most effective being n-butanal. 3. The pH optimum for the reaction is about pH 8.5–8.7. 4. Activation of enzyme catalysis by pyridoxal phosphate could not be demonstrated. The stage of growth of the bacterial cultures has no considerable influence on amination activity. 5. The role of the enzyme in bacterial biosynthesis of primary aliphatic monoamines is discussed.
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  • 65
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    Electronic Resource
    Springer
    Archives of microbiology 86 (1972), S. 255-264 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Eudorina elegans does not respond to liquid-holding or to postirradiation medium effects by changes in recovery. A decrease in survival ability is observed if a culture is starved prior to irradiation, or is incubated at 22°C rather than 32°C following UV irradiation. Eudorina loses the ability to photoreactivate UV damage within 10 to 48 h following irradiation, depending upon the pre-and post-UV culture conditions. The results are interpreted as indicating a failure of Eudorina elegans to carry out specific dark repair of UV damage. Some reactivation may occur during cellular DNA synthesis.
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  • 66
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Experiments on the relationship between nitrogen fixation and photosynthesis in intact Anabaena cylindrica are reported. 1. Uncouplers of the photosynthetic electron transport inhibit CO2-fixation as well as nitrogen fixation, as measured by the reduction of acetylene to ethylene. These experiments indicate the energy requirement for nitrogen fixation in vivo. 2. Similar to the photosynthetic CO2-fixation, also nitrogen fixation is inhibited by DSPD1 and DBMIB, suggesting that ferredoxin is the reductant for nitrogen fixation in the whole cells. 3. In far red light (above 695 nm), the photosynthetic CO2-fixation is completely inhibited by DCMU, whereas acetylene reduction is scarcely affected. These results suggest that the direct role of photosynthesis in nitrogen fixation is restricted to supply the energy by cyclic photophosphorylation at least under some experimental conditions. The reductant for the nitrogen fixation in Anabaena, ferredoxin in all probability, is likely to be reduced in a dark reaction and independently from the photosynthetic electron transport. — Some controversial results on the hypothesis, that nitrogenase in blue-green algae is located in the heterocysts, are discussed.
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  • 67
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 86 (1972), S. 281-290 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Der freie Raum innerhalb der Zellwand von Chlorella fusca wurde nach einer Verdünnungsmethode mit 14C-mannit bestimmt. 36Cl-Perchlorat ist wegen des Donnan-Effekts weniger geeignet. Korrektur für außen anhaftendes Wasser wurde mit 14C-Dextran durchgeführt. Während der Lichtphase (16 Std) des Wachstumscyclus nimmt der freie Raum von 11 auf 4% des Zellvolumens ab, und er nimmt während der ersten 8 Std der Dunkelphase (12 Std) wieder zu. Während der Lichtphase vermindert sich, nach dem Volumen des freien Raums zu urteilen, die Zellwanddicke; offenbar bleibt die Zellwandsynthese gegenüber dem Zellwachstum zurück.
    Notes: Summary The free space in the cell wall of Chlorella fusca has been determined by a dilution method with 14C-mannitol. Owing to a Donnan effect, 36Cl-perchlorate is less suitable, 14C-dextran was used to correct for external water. During the light phase (16 h) of the generation cycle, the free space decreases from 11 to 4% of the cell volume. It increases again during the first 8 h of the dark phase (12 h). During the light phase, the cell wall, as judged by the free space volume, thins; apparently cell wall synthesis does not fully kepp in step with cell growth.
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  • 68
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. [3H]N-acetylglucosamine ([3H]-NAGA) was incorporated into intact colonies of Trichoderma viride to follow autoradiographically the localization and timing of extension, initiation of new tips and other changes in the hyphal walls. 2. It was found that [3H]-NAGA incorporation differed greatly from [3H] uridine and [3H]leucine incorporation as regards labeling pattern and susceptibility to enzymes. 3. Incorporation for 6, 18 and 54 min resulted in labeling of cell wall regions in fair correspondence to the hyphal growth rate, in conformity with the assumption that chitin synthesis is mainly apical. 4. Pulse labeling indicated that hyphal tip growth took place both at the colony-margin and in a submarginal ring. The latter labeling was very conscious in photoinduced colonies where conidiophore formation was followed also by “pulse and wash” labeling. 5. The general applicability of the method to morphogenetic studies in fungal colonies is discussed.
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  • 69
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Aus einem Rohextrakt von Hydrogenomonas eutropha Stamm H16-Fructosezellen wurden eine NADP- und eine NAD-spezifische Isocitrat-Dehydrogenase teilweise gereinigt und getrennt. Beide Enzyme sind in ihrer Affinität zum Isocitrat und zu NADP bzw. NAD sehr ähnlich. Beide Enzyme werden durch ATP gehemmt, das NADP-abhängige Enzym wird außerdem durch AMP und ADP aktiviert. Das NAD-abhängige Enzym wird durch NADH2 gehemmt. Beide Enzyme werden stark gehemmt, wenn Glyoxylat und Oxalacetat gemeinsam dem Reaktionsgemisch zugesetzt werden.
    Notes: Summary From crude extracts of fructose-grown cells of Hydrogenomonas eutropha strain H 16 both a NADP- and a NAD-specific isocitrate dehydrogenase have been separated and partially purified. With respect to their affinity for isocitrate and NADP or NAD, respectively, both enzymes are very similar. Both enzymes are inhibited by ATP, the NADP-dependent enzyme is activated by AMP and ADP in addition. The NAD-specific enzyme is inhibited by NADH2. Both enzymes are highly inhibited if glyoxylate and oxalacetate are concomitantly added to the enzyme reaction mixture.
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  • 70
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Chlorella pyrenoidosa inkorporiert unter normalen Anzuchtbedingungen kurzfristig angebotenes Uridin fast ausschließlich in plastidäre ribosomale RNA. Es lassen sich rasch markierte Ribosomen und deren Untereinheiten von 70 S, 50 S und 30 S nachweisen. Diese Markierung wird durch Rifampin in geringen Konzentrationen bereits nach wenigen Minuten unterbunden. Auf das Zellwachstum hat Rifampin bei heterotropher Anzucht dagegen auch in höheren Konzentrationen keinen Einfluß. Chloramphenicol hemmt den kurzfristigen Uridin-Einbau in ribosomale Partikeln von 70 S, 50 S und 30 S, nur geringfügig dagegen denjenigen in ribosomale RNA. Auch die Wirkung des Chloramphenicols tritt rasch ein. Cycloheximid beeinflußt den Kurzzeit-Einbau von Uridin in ribosomale Partikeln und in RNA nicht, wenn die Inkubationszeit 60 min nicht überschreitet. Die Markierung der Nucleinsäuren von Chlorella mit 6-(14C)-Orotsäure zeigt vergleichbare Empfindlichkeiten gegen die drei Antibiotica wie der Einbau von 6-(14C)-Uridin und 5-(3H)-Uridin.
    Notes: Summary Normal grown cells of Chlorella pyrenoidosa incorporate uridine exclusively into chloroplast ribosomal RNA after short time labeling. With sucrose gradient separation, labeled ribosomal particles of 70 S, 50 S and 30 S can be shown. This labeling is prevented by rifampin in low concentrations after a few minutes. At the same concentration of the antibiotic and also with 10-fold higher concentration, no effect on heterotrophic cell growth is observed. This indicates clearly that mitochondria cannot be influenced by rifampin. Chloramphenicol also inhibits the formation of uridine labeled ribosomal particles of 70 S, 50 S and 30 S. In the presence of this antibiotic, some labeled ribosomal RNA is formed. Also the effect of chloramphenicol can be shown after short incubation periods. Cycloheximide treatment of the cells within 30 and 60 min and up to the 10-fold concentration of protein synthesis inhibition (Morris, 1967) results in no effect on labeling of ribosomal RNA and of ribosomal particles in Chlorella with uridine. Only after prolonged treatment of the cells with cycloheximide is some effect on uridine incorporation observed. The comparison of the incorporation patterns of 6-(14C)-orotate, (6-14C)-uridine and 5-(3H)-uridine into nucleic acids in the presence of rifampin, chloramphenicol and cycloheximide shows some similarities. After 60 min incubation with the precursors, the incorporation is reduced by all three antibiotics. In rifampin treated cells, orotate and both uridines are preferentially incorporated into DNA. With chloramphenicol, the relative incorporation of orotate and of uridine into the 5 S and the 16 S RNA is higher as compared with the 23 S RNA. Cycloheximide results in an increase in the relative incorporation of orotate as well of uridine into DNA. The similarities of the effects of the three antibotics indicate that the preferential incorporation of uridine into chloroplast ribosomes of Chlorella is not due to a compartmentation of the uridine-UMP-pathway.
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