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  • 1
    Digitale Medien
    Digitale Medien
    Box schemes on quadrilateral meshes (1993)
    Springer
    Computing 51 (1993), S. 271-292 
    Details
    ISSN: 1436-5057
    Schlagwort(e): 65N15 ; 65N99 ; 35A40 ; Box method ; boundary value problem ; finite volume method ; variational formulation ; stability ; error bounds
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Box-Methoden (Finite-Volumen-Methoden) sind verbreitete Verfahren zur Lösung physikalischer Erhaltungsgleichungen, insbesondere in der Strömungsmechanik. In dieser Arbeit werden zwei Methoden für elliptische Differentialgleichungen untersucht, die Diagonal-Boxen und die Schwerpunkt-Boxen. Da die Box-Methoden im Sinne von Petrov-Galerkin-Verfahren interpretiert werden können, erhält man vergleichbar zur Finiten-Element-Methode eine variationsrechnerische Stabilitäts- und Fehleranalyse. Damit werdenO(h)- undO(h 2)-Fehlerabschätzungen hergeleitet. Lokale Eigenwertprobleme führen zu Stabilitätsaussagen. Allerdings ergibt sich eine Abhängigkeit von der Anzahl und Art gestörter Vierecke. Insbesondere die Diagonal-Boxen sind anfällig für lokale Störungen.
    Notizen: Abstract Box schemes (finite volume methods) are widely used in fluiddynamics, especially for the solution of conservation laws. In this paper two box-schemes for elliptic equations are analysed with respect to quadrilateral meshes. Using a variational formulation, we gain stability theorems for two different box methods, namely the so-called diagonal boxes and the centre boxes. The analysis is based on an elementwise eigenvalue problem. Stability can only be guaranteed under additional assumptions on the geometry of the quadrilaterals. For the diagonal boxes unsuitable elements can lead to global instabilities. The centre boxes are more robust and differ not so much from the finite element approach. In the stable case, convergence results up to second order are proved with well-known techniques.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02238536
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  • 2
    Digitale Medien
    Digitale Medien
    Quantitative stability of variational systems: III.ε-approximate solutions (1993)
    Springer
    Mathematical programming 61 (1993), S. 197-214 
    Details
    ISSN: 1436-4646
    Schlagwort(e): Epi-convergence ; epi-distance ; stability ; convex optimization ; approximate solutions ; subgradients ; level sets
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik , Mathematik
    Notizen: Abstract We prove that theε-optimal solutions of convex optimization problems are Lipschitz continuous with respect to data perturbations when these are measured in terms of the epi-distance. A similar property is obtained for the distance between the level sets of extended real valued functions. We also show that these properties imply that theε-subgradient mapping is Lipschitz continuous.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01582147
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  • 3
    Digitale Medien
    Digitale Medien
    Effect of experience on in-flight orientation to host-associated cues in the generalist parasitoidLysiphlebus testaceipes (1993)
    Springer
    Entomologia experimentalis et applicata 68 (1993), S. 219-229 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Hymenoptera ; Aphidiidae ; Homoptera ; Aphididae ; Schizaphis graminum ; wheat ; tritrophic interactions ; learning ; host-habitat location
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The effect of experience on the responsiveness of the aphidiid parasitoidLysiphlebus testaceipes (Cresson) (Hymenoptera: Aphidiidae) to host-associated cues was investigated using a wind-tunnel bioassay. Naive females were able to discriminate between uninfested wheat (Triticum aestivum L.) and wheat infested withSchizaphis gramimum (Rondani) (Homoptera: Aphididae), but oviposition experience significantly increased the parasitoid's propensity to respond to aphid-infested plants with upwind, targeted flight. The behavioural change associated with such experience was acquired rapidly (within five minutes) and persisted for at least 24 h. The parasitoid could be successfully conditioned to associate a novel odour with the presence of hosts, suggesting that the increase in response to aphid-infested plants which occurs as a result of experience is probably due to associative learning of olfactory cues from the plant-aphid complex.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02380774
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  • 4
    Digitale Medien
    Digitale Medien
    Variation between strains of the flour beetle Tribolium castaneum in relative performance on five flours (1991)
    Springer
    Entomologia experimentalis et applicata 60 (1991), S. 173-182 
    Details
    ISSN: 1570-7458
    Schlagwort(e): Genetics ; evolution ; host adaptation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract When populations are exposed to different environments, evolutionary processes can lead either to genetically differentiated strains or to the appearance of increased generalism at the individual level. For evolution to occur, genetic variability in performance in different environments is required. Here, intraspecific genetic variation across environments was estimated in the flour beetle Tribolium castaneum (Herbst) by comparing the responses of two strains of T. castaneum to different flour types. Replicated groups from each strain were allowed to develop on either the standard whole wheat medium or on one of four novel flours (wheat, rice, corn and oat). In several of the novel flours, clear differences in mean development time or population size of one or both strains were seen relative to performance in the standard medium. Moreover, the strains differed significantly in their phenotypic responses to the flours. One strain did particularly poorly on oat flour. Reduced oviposition, reduced larval survivorship and increased larval cannibalism were examined as possible causes of the low productivity on oat flour. These three factors accounted for about 70% of the reduction in population size when this strain oviposited and developed in oat flour. The difference between these two outbred strains in response to these five flours suggests that genetic variation in resource use is present within T. castaneum and may also be present within strains and natural populations in grain storage facilities. Such variation would permit an evolutionary response to selection in multiple environments (flours). This process has agricultural implications when several types of grain are stored in a single location because it could eventually lead to the evolution of highly generalized populations of T. castaneum, an important pest of stored products.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00177038
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  • 5
    Digitale Medien
    Digitale Medien
    Stability properties of proliferatively coupled cell replication models (1991)
    Springer
    Acta biotheoretica 39 (1991), S. 1-14 
    Details
    ISSN: 1572-8358
    Schlagwort(e): Hematological diseases ; first order partial differential equations ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract To address the possibility that proliferative disorders may originate from interactions between multiple populations of proliferating and maturing cells, we formulate a model for this process as a set of coupled nonlinear first order partial differential equations. Using recent results for the asymptotic behaviour of the solutions to this model, we demonstrate that there exists a region of coupling coefficients, maturation rates, and proliferation rates that will guarantee the stable coexistence of coupled cellular populations. The analysis shows that increases in the coupling between populations may ultimately lead to a loss of stability. Furthermore, the analysis indicates that increases (decreases) in the maturation and/or proliferation rates above (below) critical levels will lead either to instability in the populations or the destruction of one population and the persistence of the other.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00046404
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  • 6
    Digitale Medien
    Digitale Medien
    Assembly Coplanner: co-operative assembly planner based on subassembly extraction (1993)
    Springer
    Journal of intelligent manufacturing 4 (1993), S. 183-198 
    Details
    ISSN: 1572-8145
    Schlagwort(e): Assembly planning ; subassembly ; liaison graph ; geometric reasoning ; assembly cost ; stability ; partial-order graph
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau
    Notizen: The distribution of assembly workstations enables assembly operations to be done in parallel, while the multiple routing of parts in flexible assembly systems allows the opportunistic scheduling of assembly operations. This paper presents an assembly planning system, called the Assembly Coplanner, which automatically constructs an assembly partial order and generates a set of assembly instructions from a liaison graph representation of an assembly based on the extraction of preferred subassemblies. Assembly planning in Coplanner is carried out by the co-operation of multiple planning agents, such as the geometric reasoner, the physical reasoner, the resource manager and the plan coordinator, under the constraints of finding a cost-effective assembly plan in a flexible assembly system. The Coplanner identifies spatial parallelism in assembly as a means of constructing temporal parallelism among assembly operations. This is achieved in the following way: (1) the selection of a set of tentative subassemblies by decomposing a liaison graph into a set of subgraphs based on feasibility and difficulty of disassembly; (2) the evaluation of each of the tentative subassemblies in terms of assembly cost represented by subassembly selection indices; and (3) the construction of a hierarchical partial order graph (HPOG) as an assembly plan. A case study applying the Coplanner to a mechanical assembly is illustrated in this paper.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00123963
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  • 7
    Digitale Medien
    Digitale Medien
    Chemiluminescence in evaluating the thermal oxidative stability of acrylonitrile-butadiene-styrene (ABS) copolymers. II. ABS/polycarbonate (PC) blends (1993)
    Springer
    Journal of polymers and the environment 1 (1993), S. 275-279 
    Details
    ISSN: 1572-8900
    Schlagwort(e): Chemiluminescence ; oxidation ; stability ; acrylonitrile-butadiene-styrene (ABS) ; ABS/polycarbonate blend
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Energietechnik , Maschinenbau
    Notizen: Abstract The thermal oxidative stability of various ABS/PC compounds was studied by means of the chemiluminescence technique. Similarly to pure ABS, Irganox 1076 and Irganox MD 1024 perform as moderate antioxidants in ABS/PC and (ABS/PC + lubricant) blends. Neither Tinuvin 144, Irgaphos 168, nor their mixture affects the durability of the ABS/PC blend. At the same time, (Irgaphos 168 + Tinuvin 144) in combination with Irganoxes was found to provide a noticeable enhancement in durability to the (ABS/PC + lubricant) system. Titanium dioxide pigments by themselves have only a slight influence on the oxidative stability of the ABS/PC blend. Durability of the (ABS/PC + pigment) and (ABS/PC + lubricant) systems was found to be the same and the overall protective effect of Irganox 1076 was similar in both the (ABS/PC + lubricant) and the (ABS/PC + lubricant + pigment) systems. Certain modifiers significantly improve the durability of the ABS/PC compounds, although their function may differ in the systems with and without pigments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01458294
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  • 8
    Digitale Medien
    Digitale Medien
    Cockroach mating behaviors, sex pheromones, and abdominal glands (Dictyoptera: Blaberidae) (1993)
    Springer
    Journal of insect behavior 6 (1993), S. 715-735 
    Details
    ISSN: 1572-8889
    Schlagwort(e): Aphrodisiac ; cockroach ; evolution ; mating behavior ; sex pheromone ; sternal glands ; tergal glands
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Two chemical signals are essential in all cockroach sexual behavioral sequences: the sex pheromone released by one partner, generally the female (for long distance attraction), and an aphrodisiac sex pheromone produced exclusively by male tergal glands (for female mounting and tergal contact or “feeding” behavior). Unlike the other cockroach groups, the males of the Oxyhaloinae species produce both chemical signals: the pheromone and the aphrodisiac. The occurrence of three patterns of mating behavior (A, B, and C), the production of male sex pheromones, and the existence in the male of developed sternal and tergal glands in seven related Oxyhaloinae species, make these cockroaches a useful model for studying the evolution of mating behavior patterns. The various types of mating behavior were not classified in the previous studies by Roth and Barth. In this report, they have been named type A (female in upper position), B (male in upper position), and C (male and female end to end). In type A mating, the male tergal glands, which are licked by the females, are well developed, whereas in types B and C, there is no licking of the male's tergal secretion by the females and the tergal glands are much less developed; the aphrodisiacs secreted by the tergal glands may no longer act in this case through contact chemoreception, but through an olfactory process involving volatile components. One common sex pheromone component seems to be acetoin. I suggest that the mating behavior tends from A toward B and C during the evolutionary process with a concomitant regression of the tergal glands and changes in the aphrodisiac emission levels. The mating behavioral sequences of cockroaches (Dictyoptera) and crickets (Orthoptera) show a striking degree of similarity and are probably examples of convergent evolution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01201672
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  • 9
    Digitale Medien
    Digitale Medien
    Chemiluminescence in evaluating the thermal oxidative stability of acrylonitrile-butadiene-styrene (ABS) copolymers. 1. Influence of stabilizers and lubricants (1993)
    Springer
    Journal of polymers and the environment 1 (1993), S. 107-110 
    Details
    ISSN: 1572-8900
    Schlagwort(e): Chemiluminescence ; oxidation ; stability ; acrylonitrile-butadiene-styrene (ABS)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Energietechnik , Maschinenbau
    Notizen: Abstract The influence of lubricants, UV stabilizers, antioxidants, and metal deactivators on the resistance of ABS to thermal oxidation was studied by means of the chemiluminescence technique. Neither of the additives seems to affect significantly the induction period of oxidation. At the same time, the influence of various additives on the oxidation rate constant is remarkably different: the introduction of lubricants and UV stabilizers increases its value, while antioxidants and metal deactivators have the opposite effect. For the particular systems studied durability is decreased in samples containing the lubricant and UV stabilizers and increased in samples stabilized with the antioxidant and metal deactivator.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01418203
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  • 10
    Digitale Medien
    Digitale Medien
    Egg attendance and brooding by males of the giant water bugLethocerus medius (Guerin) in the field (Heteroptera: Belostomatidae) (1993)
    Springer
    Journal of insect behavior 6 (1993), S. 93-106 
    Details
    ISSN: 1572-8889
    Schlagwort(e): Belostomatidae ; giant water bugs ; paternal care ; eggs ; reproduction ; behavior ; brooding ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Males of the giant water bug Lethocerus medius(Guerin) typify their monobasic subfamily, the Lethocerinae, in that they do not brood eggs attached to their backs as do males of all members of the subfamily Belostomatinae. Exclusive male parental investment as expressed in the Belostomatinae is extremely rare behavior among animals, and evolution of the trait is obscure. Lethocerus mediusmales apparently remain with their mates through oviposition and are consistently found in attendance of eggs after the female has departed. This behavior may enhance paternity assurance at no cost in opportunity for polygyny. Two double clutches of eggs were found, from which we infer the potential for polygynous matings and shared parental investment. Male L. mediusbrood attended egg clutches above the surface of the water, where they may moisten them, shade them, and defend them against predation. Egg attendance/brooding by L. mediusand other Lethocerusspecies may represent a plesiomorphic state from which paternal back- brooding evolved in the Belostomatinae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01049150
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  • 11
    Digitale Medien
    Digitale Medien
    Influence of washing and of heat-treatment conditions on the thermal stability of VPI-5 (1991)
    Springer
    Catalysis letters 10 (1991), S. 225-232 
    Details
    ISSN: 1572-879X
    Schlagwort(e): VPI-5 ; stability ; molecular sieve ; post-synthesis treatments
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Thorough washing of a VPI-5 synthesized with n-dipropylamine as template improves greatly its thermal stability while no major change is observed in the template content. A detailed study of the influence of the pretreatment conditions shows that in order to obtain a high thermal stability (up to at least 960 °C) two parameters are of importance. The removal of both the template and the adsorbed water requires either a low heating rate at atmospheric pressure or a low pressure (less than 3 Torr) when the heating rate is 300 ° per hour.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00772075
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  • 12
    Digitale Medien
    Digitale Medien
    Re-entrant lines (1993)
    Springer
    Queueing systems 13 (1993), S. 87-110 
    Details
    ISSN: 1572-9443
    Schlagwort(e): Manufacturing systems ; semiconductor manufacturing ; thin film lines ; re-entrant lines ; scheduling policies ; queueing networks ; buffer priority policies ; due date policies ; stability ; stochastic control ; mean delay ; variance of delay ; machine failures ; set-up times
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract Traditionally, manufacturing systems have mainly been treated as either job shops or flow shops. In job shops, parts may arrive with random routes, with each route having a low volume. In flow shops, the routes are fixed and acyclic, as in assembly lines. With the advent of semiconductor manufacturing plants, and more recently, thin film lines, this dichotomy needs to be expanded to consider another class of systems, which we call “re-entrant lines”. The distinguishing feature of these manufacturing systems is that parts visit some machines more than once at different stages of processing. Scheduling problems arise because several parts at different stages of processing may be in contention with each other for service at the same machine. There may be uncertainties in the form of random service or set-up times, as well as random machine failures and repairs. The goal of scheduling is to improve performance measures such as mean sojourn time in the system, which is also known as the mean “cycle-time”, or the variance of the cycle-time. In this paper we provide a tutorial account of some recent results in this field. We describe several scheduling policies of interest, and provide some results concerning their stability and performance. Several open problems are suggested.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01158930
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  • 13
    Digitale Medien
    Digitale Medien
    Stable planetary orbits around one component in nearby binary stars. II (1993)
    Springer
    Celestial mechanics and dynamical astronomy 56 (1993), S. 45-50 
    Details
    ISSN: 1572-9478
    Schlagwort(e): Restricted problem ; stability ; planets of double stars
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract Numerical simulations are made within the framework of the plane restricted three-body problem, in order to find out if stable orbits for planets around one of the two components in double stars can exist. For any given set of initial parameters (the mass ratio of the two stars and the eccentricity of their orbit around each other), the phase-space of initial positions and velocities is systematically explored. In previous works, systematic exploration of the circular model as well as studies of more realistic (elliptic) cases such as Sun-Jupiter and the nearby α Centauri and Sirius systems, large stable planetary orbits were found to exist around both components of the binary, up to distances from each star of the order or more than half the binary's periastron separation. The first results presented here for the η Coronae Borealis system confirm the previous studies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00699718
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  • 14
    Digitale Medien
    Digitale Medien
    Stability characteristics of transition layer solutions (1993)
    Springer
    Journal of dynamics and differential equations 5 (1993), S. 625-671 
    Details
    ISSN: 1572-9222
    Schlagwort(e): Scalar reaction-diffusion equation ; singular perturbation methods ; internal layer ; Neumann layer ; stability ; 35K57 ; 35B25 ; 35B35
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract The multiple existences and their stability properties of stationary solutions with a single transition layer in some scalar reaction-diffusion equation are shown. Each solution is constructed by using classical singular perturbation methods and its stability property is determined by a simple algebraic quantity, say index, appearing in the construction of a solution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01049142
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  • 15
    Digitale Medien
    Digitale Medien
    Open queueing networks in discrete time-some limit theorems (1993)
    Springer
    Queueing systems 14 (1993), S. 159-175 
    Details
    ISSN: 1572-9443
    Schlagwort(e): Queueing networks ; nonproduct form networks ; stability ; stochastic continuity ; functional limit theorems
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract A finite number of nodes, each with a single server and infinite buffers, is considered in discrete time. The service may be FIFO and the service times are constant. The external arrivals and the routing decision variables form a general stationary sequence. Stability of the system is proved under these assumptions. Extension to multiple servers at a node and general stationary distributions holds. If the external input is i.i.d. and the routing is Markovian then stochastic ordering, continuity of stationary distributions, rates of convergence, a functional CLT and a functional LIL and various other limit theorems for the queue length process are also proved. Generalizations to multiple servers at nodes, customers with priority, multiple customer classes, general service length and Markov modulated external arrival cases are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01153532
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  • 16
    Digitale Medien
    Digitale Medien
    Equivariant multiparameter bifurcation via singularity theory (1993)
    Springer
    Journal of dynamics and differential equations 5 (1993), S. 189-218 
    Details
    ISSN: 1572-9222
    Schlagwort(e): Equivariant bifurcation ; symmetry ; singularity ; equivariant jets and transversality ; normal forms ; universal unfolding ; stability ; structural stability ; 58F14 ; 58E07 ; 58C27
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract The theoretical machinery from singularity theory introduced by Golubitsky, Stewart, and Schaeffer, to study equivariant bifurcation problems, is completed and expanded while generalized to the multiple parameter context. In this setting the finite determinacy theorems or normal forms, the stability of equivariant bifurcation problems, and the structural stability of the universal unfolding are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01053160
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  • 17
    Digitale Medien
    Digitale Medien
    Perturbed unstable variational inequalities with unbounded operators on approximately given sets (1993)
    Springer
    Set-valued analysis 1 (1993), S. 393-402 
    Details
    ISSN: 1572-932X
    Schlagwort(e): Primary: 49J40, 65K10, 47A55, 47H05, 65L20 ; Variational inequality ; perturbation ; unbounded and nonsmooth operators ; convex sets ; Hausdorff distance ; regularization ; monotonicity ; convergence ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract The stability and convergence of the solutions of perturbed and regularized variational inequality to the solutions of the primary (unstable a priori) variational inequality with proper monotone operator are investigated. All the objects of inequality: the operatorA, the right-hand partf and the set of constrains Ω are to be perturbed. At the same time no assumptions of boundedness and smoothness of the operatorA are used. The connection between the parameters of perturbations, which guarantees strong convergence of approximate solutions, is established. It is proved that the existence of the solution to the unperturbed variational inequality is necessary and sufficient condition for convergence of the regularized perturbed inequality solutions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01027828
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  • 18
    Digitale Medien
    Digitale Medien
    The relative variance criterion for stability of delay systems (1993)
    Springer
    Journal of dynamics and differential equations 5 (1993), S. 105-128 
    Details
    ISSN: 1572-9222
    Schlagwort(e): Delay system ; stability ; relative variance ; dynamical disease
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract A new approach to the study of delay systems, applicable to physiological control systems and other systems where little information about the time delays is available, is examined. The method is based on the fact that stability information can be deduced from the statistical properties of the probability distribution that encodes the structure of the time delay. The main statistical variables used are the usual expectation parameter,E, and a modified variance, calledrelative variance and denotedR, that is invariant under time scale changes. Recent work of the author has shown that stability often improves asR increases whileE remains fixed. A four-parameter family of delay models is analysed in this paper, and the (E, R) pair is found to be a reliable indicator of stability over the global parameter domain of the family.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01063737
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  • 19
    Digitale Medien
    Digitale Medien
    Interaction of nicotine with π and σ electron acceptors (1993)
    Springer
    Journal of solution chemistry 22 (1993), S. 1151-1158 
    Details
    ISSN: 1572-8927
    Schlagwort(e): Molecular complexes ; solvent effect ; stability ; solid CT complexes ; nicotine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Interaction of nicotine with tetracyanoethylene and iodine was investigated spectrophotometrically and found to form strong CT complexes (n−π and n-σ*, respectively). The donor site involved in CT interaction is the pyrrolidine nitrogen. The nicotine-I2 complex exists as the ionic structure (nicotine) I+-I 3 − . Formation constants of the CT complexes in various solvents were determined from 10 to 25°C and are discussed in terms of the nature of the electron acceptor and solvent polarity. Solid CT complexes were synthesized and were characterized by microchemical analysis and infrared spectra techniques.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00651696
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  • 20
    Digitale Medien
    Digitale Medien
    On the first eigenvalue of the linearized operator of ther-th mean curvature of a hypersurface (1993)
    Springer
    Annals of global analysis and geometry 11 (1993), S. 387-395 
    Details
    ISSN: 1572-9060
    Schlagwort(e): Curvatures of hypersurfaces ; Reilly's inequality ; stability ; 53 A 10 ; 53 C 42
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract We generalize Reilly's inequality for the first eigenvalue of immersed submanifolds ofIR m +1 and the total (squared) mean curvature, to hypersurfaces ofIR m +1 and the first eigenvalue of the higher order curvatures. We apply this to stability problems. We also consider hypersurfaces in hyperbolic space.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00773553
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  • 21
    Digitale Medien
    Digitale Medien
    Numerical experiments with a multistep Radau method (1993)
    Springer
    BIT 33 (1993), S. 332-350 
    Details
    ISSN: 1572-9125
    Schlagwort(e): AMS(MOS): 65L06 ; Multistep collocation method ; continuous solution ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract This paper describes an implementation of multistep collocation methods, which are applicable to stiff differential problems, singular perturbation problems, and D.A.E.s of index 1 and 2. These methods generalize one-step implicit Runge-Kutta methods as well as multistep one-stage BDF methods. We give numerical comparisons of our code with two representative codes for these methods, RADAU5 and LSODE.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01989754
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  • 22
    Digitale Medien
    Digitale Medien
    Some remarks on the second variation formula for the area (1993)
    Springer
    Annals of global analysis and geometry 11 (1993), S. 221-235 
    Details
    ISSN: 1572-9060
    Schlagwort(e): Second variation formula ; Morse index ; stability ; 53C
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract Iff is a minimal, isometric immersion of the Riemannian manifoldM of dimensionn in a Riemannian manifold $$\overline M$$ of dimensionm and ifI N is the „differential Jacobi operator” acting on the cross sections of the normal bundleN(M), we obtain some information on the Morse index and on the stability ofM through a detailed geometric analysis of the immersionf obtained when considering the higher fundamental forms off.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00773368
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  • 23
    Digitale Medien
    Digitale Medien
    Asteroid 522 Helga is chaotic and stable (1993)
    Springer
    Celestial mechanics and dynamical astronomy 56 (1993), S. 323-324 
    Details
    ISSN: 1572-9478
    Schlagwort(e): chaos ; stability ; asteroids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00699743
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  • 24
    Digitale Medien
    Digitale Medien
    The Trojan asteroid belt: Proper elements, stability, chaos and families (1993)
    Springer
    Celestial mechanics and dynamical astronomy 57 (1993), S. 59-94 
    Details
    ISSN: 1572-9478
    Schlagwort(e): asteroids ; libration ; proper elements ; stability ; chaos ; families
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract I have computed proper elements for 174 asteroids in the 1 : 1 resonance with Jupiter, that is for all the reliable orbits available (numbered and multi-opposition). The procedure requires numerical integration, under the perturbations by the four major planets, for 1,000,000 years; the output is digitally filtered and compressed into a “synthetic theory” (as defined within theLONGSTOP project). The proper modes of oscillation of the variables related to eccentricity, perihelion, inclination and node define proper elements. A third proper element is defined as the amplitude of the oscillation of the semimajor axis associated with the libration period; because of the strong nonlinearity of the problem, this component cannot be determined by a simple Fourier transform to the frequency domain. I therefore give another definition, which results in very good stability with time. For 87% of the computed orbits, the stability of the proper elements-at least over 1M yr-is within the following bounds: 0.001AU in semimajor axis, 0.0025 in eccentricity and sine of inclination. Half of the cases with degraded stability of the proper elements are found to be chaotic, with e-folding times between 16,000 and 660,000yr; in some other cases, chaotic behaviour does not result in a significantly decreased stability of the proper elements (stable chaos). The accuracy and stability of these proper elements is good enough to allow a search for asteroid families; however, the dynamical structure of the Trojan belt is very different from the one of the main belt, and collisional events among Trojans can result in a distribution of fragments difficult to identify. The occurrence of couples of Trojans with very close proper elements is proven not to be statistically significant in almost all cases. As the only exception, the couple 1583 Antilochus — 3801 Thrasimedes is significant; however, it is not easy to account for it by a conventional collisional theory. The Menelaus group is confirmed as a strong candidate collisional family; Teucer and Sarpedon could be considered as significant clusters. A number of other clumps are detected (by the same automated clustering method used for the main belt by Zappalà et al., 1990, 1992), but the total number of Trojans with reliable orbits is not large enough to detect many significant candidate families.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00692462
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  • 25
    Digitale Medien
    Digitale Medien
    The integrable cases of the planetary three-body problem at first-order resonance (1993)
    Springer
    Celestial mechanics and dynamical astronomy 55 (1993), S. 249-259 
    Details
    ISSN: 1572-9478
    Schlagwort(e): Asteroid ; libration ; resonance ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract This paper investigates the stability of the motion in the averaged planar general three-body problem in the case of first-order resonance. The equations of the averaged motion of bodies near the resonance surface is obtained and is analytically integrated by quadratures. The stability of the averaged motion is analytically investigated in relation to the semi-major axes, the eccentricities and the resonance phases. An autonomous second-order equation is obtained for the deviation of semiaxes from the resonance surface. This equation has an energy integral and is analytically integrated by quadratures. The quasi-periodic dependence on time with two-frequency basis of the averaged motion of bodies is found. The basic frequencies are analytically calculated. With the help of the mean functionals calculated along integral curves of the averaged problem the new analytic first integrals are constructed with coefficients periodic in time. The analytic conditions of librations of resonance phases are obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00692513
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  • 26
    Digitale Medien
    Digitale Medien
    About the periodic solutions of a rigid body in a central Newtonian field (1993)
    Springer
    Celestial mechanics and dynamical astronomy 55 (1993), S. 323-330 
    Details
    ISSN: 1572-9478
    Schlagwort(e): Periodic orbits ; rigid body dynamics ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The equations of motion of a rigid body about a fixed point in a central Newtonian field is reduced to the equation of plane motion under the action of potential and gyroscopic forces, using the isothermal coordinates on the inertia ellipsoid. The construction of periodic solutions near the equilibrium points, by using the Lipaunov theorem of holomorphic integral, is obtained and the necessary and sufficient conditions for the stability of the system are given.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00692992
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  • 27
    Digitale Medien
    Digitale Medien
    Invariant rotational curves in Sitnikov's Problem (1993)
    Springer
    Celestial mechanics and dynamical astronomy 55 (1993), S. 351-367 
    Details
    ISSN: 1572-9478
    Schlagwort(e): Sitnikov's problem ; invariant rotational curves ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract The Sitnikov's Problem is a Restricted Three-Body Problem of Celestial Mechanics depending on a parameter, the eccentricity,e. The Hamiltonian,H(z, v, t, e), does not depend ont ife=0 and we have an integrable system; ife is small the KAM Theory proves the existence of invariant rotational curves, IRC. For larger eccentricities, we show that there exist two complementary sequences of intervals of values ofe that accumulate to the maximum admissible value of the eccentricity, 1, and such that, for one of the sequences IRC around a fixed point persist. Moreover, they shrink to the planez=0 ase tends to 1.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00692994
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  • 28
    Digitale Medien
    Digitale Medien
    The stability of rational approximations of analytic semigroups (1993)
    Springer
    BIT 33 (1993), S. 74-84 
    Details
    ISSN: 1572-9125
    Schlagwort(e): 65J10 ; 65M12 ; Analytic semigroup ; Banach space ; rational approximation ; A-acceptable ; A(θ)-acceptable ; stability ; Crank-Nicolson method
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract It is shown thatA-acceptable and, more generally,A(θ)-arational approximations of bounded analytic semigroups in Banach space are stable. The result applies, in particular, to the Crank-Nicolson method.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01990345
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  • 29
    Digitale Medien
    Digitale Medien
    Stiffness of ODEs (1993)
    Springer
    BIT 33 (1993), S. 285-303 
    Details
    ISSN: 1572-9125
    Schlagwort(e): 65L05 ; stiffness ; stability ; pseudospectra
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract It is argued that even for a linear system of ODEs with constant coefficients, stiffness cannot properly be characterized in terms of the eigenvalues of the Jacobian, because stiffness is a transient phenomenon whereas the significance of eigenvalues is asymptotic. Recent theory from the numerical solution of PDEs is adapted to show that a more appropriate characterization can be based upon pseudospectra instead of spectra. Numerical experiments with an adaptive ODE solver illustrate these findings.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01989751
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  • 30
    Digitale Medien
    Digitale Medien
    Biology of halophilic bacteria, Part II (1993)
    Springer
    Cellular and molecular life sciences 49 (1993), S. 1027-1036 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Archaea (archaebacteria) ; extreme halophiles ; archaeol phospholipids ; archaeol glycolipids ; membrane function ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Archaebacteria (archaea) are comprised of three groups of prokaryotes: extreme halophiles, methanogens and thermoacidophiles (extreme thermophiles). Their membrane phospholipids and glycolipids are derived entirely from a saturated, isopranoid glycerol diether,sn-2,3-diphytanylglycerol (‘archaeol’) and/or its dimer, dibiphytanyldiglyceroltetraether (‘caldarchaeol’). In extreme halophiles, the major phospholipid is the archaeol analogue of phosphatidylglycerolmethylphosphate (PGP-Me); the glycolipids are sulfated and/or unsulfated glycosyl archaeols with diverse carbohydrate structure characteristic of taxons on the generic level. Biosynthesis of these archaeol-derived polar lipids occurs in a multienzyme, membrane-bound system that is absolutely dependent on high salt concentration (4 M). The highly complex biosynthetic pathways involve intermediates containing glycerol ether-linked C20-isoprenyl groups which are reduced to phytanyl groups to give the final saturated polar lipids. In methanogens, polar lipids are derived both from archaeol and caldarchaeol, and thermoacidophiles contain essentially only caldarchaeol-derived polar lipids. The function of these membrane polar lipids in maintaining the stability, fluidity and ionic properties of the cell membrane of extreme halophiles, as well as the evolutionary implications of the archaeol and caldarchaeol-derived structures will be discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01929909
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  • 31
    Digitale Medien
    Digitale Medien
    Chitin in the epidermal cuticle of a vertebrate (Paralipophrys trigloides, Blenniidae, Teleostei) (1993)
    Springer
    Cellular and molecular life sciences 49 (1993), S. 317-319 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Chitin ; cuticle ; evolution ; vertebrates ; bony fish ; Blenniidae ; Paralipophrys trigoides
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Lectin binding, endo-chitinase binding and enzymatic degradation studies show that the epidermal cuticle of the bony fishParalipophrys trigloides (Blenniidae) is chitinous. This is the first evidence that a vertebrate species possesses a chitinous tissue. Recently aXenopus gene has been identified which has significant sequence similarity to the catalytic domain of yeast chitin synthase III, a chitin producing enzyme1,2. Taken together these two findings imply that chitin synthesis capability may be a basic vertebrate feature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01923410
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  • 32
    Digitale Medien
    Digitale Medien
    Evolution: Teleology or chance? (1991)
    Springer
    Journal for general philosophy of science 22 (1991), S. 133-141 
    Details
    ISSN: 1572-8587
    Schlagwort(e): evolution ; teleology ; chance ; purpose ; anthropomorphism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Philosophie , Wissenschaftskunde und Wissenschaftsorganisation, Hochschul- und Universitätswesen, Museumswissenschaft
    Notizen: Summary Revaluation of the problem of natural teleology seems an important precondition for elucidating our environmental crisis and for formulating an ‘ecological ethics’, because it calls for a recognition of an intrinsic value in nature and organisms. Therefore, it is necessary to show that the concept of natural teleology is not in contradiction with scientific theories, in particular not with the theory of evolution. In this paper I shall argue that there is a fundamental misunderstanding about the concepts of teleology and chance in modern thinking. This as a result of a radical transformation of the Aristotelian concept of teleology by Christian theologians during the Middle Ages. This confusion resulted in the rejection of teleology from evolution and in an exaggeration of the role of chance. However, not a solution for the problem of teleology is given here, but only an attempt to prove that neither the fossil-record, nor the role of chance in evolution can give adequate arguments for the negation of teleology in evolution. That is not to say that, therefore there exists teleology in evolution, but the problem of teleology in nature cannot, be solved by the scientific theory of evolution, but only be elucidated by philosophical analysis. At the end of the paper it is argued that teleology must be rather presupposed in evolution.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01801253
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  • 33
    Digitale Medien
    Digitale Medien
    Evolution of insect-plant relationships — a devil's advocate approach (1993)
    Springer
    Entomologia experimentalis et applicata 66 (1993), S. 3-12 
    Details
    ISSN: 1570-7458
    Schlagwort(e): evolution ; coevolution ; selection ; insect attack ; plant defense ; competition ; enemy free space ; chemoreception ; specialization ; plant recognition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Most hypotheses concerning the evolution of insect-plant relationships are based on the assumptions that, (1) phytophagous insects reduce plant fitness, and that (2) insect-plant relationships are the result of unconstrained selection. It can be shown, however, that there is little evidence to support these assumptions. As an alternative, it is proposed that the evolution of insect-plant relationships results primarily from autonomous evolutionary events; namely from heritable functional changes within the insects' nervous system that determine plant recognition and ultimately host plant specificity. These changes cannot be evoked by selective ecological agents. They originate from intrinsic changes (mutationssensu lato) within the insect genome. Ecological factors play a secondary role: by either supporting or preventing the establishment of the new genotype with the novel food preference.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02381541
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  • 34
    Digitale Medien
    Digitale Medien
    Opsin localization and chromophore retinoids identified within the basal brain of the lizard Anolis carolinensis (1993)
    Springer
    Journal of comparative physiology 172 (1993), S. 33-45 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Photoreception ; Extraretinal Photoreceptor ; Chromophore ; Opsin ; Reptile ; Immunocytochemistry ; HPLC
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Since the beginning of this century evidence has accumulated which demonstrates that non-mammalian vertebrates possess photoreceptors situated deep within the brain. While many attempts have been made to localize these sensory cells, studies have either failed or been inconclusive. In this report we have used several experimental approaches to localize the deep brain photoreceptors of the lizard Anolis carolinensis. Using 3 antibodies that bind vertebrate cone opsins, we have immunolabelled cerebrospinal fluid (CSF)-contacting neurons located at the ventricular border within the nucleus ventromedialis of the septum. Western blot analysis indicates that these antibodies recognized a single 40 kD protein in ocular, anterior brain, and pineal extracts. Immunoblots of rodent brain did not show a similar protein band. We have also identified specific retinoids associated with phototransduction (11-cis and all-trans-3,4-didehydroretinaldehyde) within anterior brain extracts. This combined data provides the most detailed analysis of deep brain photoreceptors in any vertebrate. Consequently, we feel Anolis provides an excellent model to study this unexplored sensory system of the vertebrates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00214713
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  • 35
    Digitale Medien
    Digitale Medien
    Isolation of an egg-laying hormone-binding protein from the gonad of Aplysia californica and its localization in oocytes (1993)
    Springer
    Journal of comparative physiology 173 (1993), S. 475-483 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Egg laying hormone ; Aplysia ; Binding protein ; Immunocytochemistry ; Reproductive system
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract A protein solubilized from a membrane preparation of the gonad of Aplysia californica has been isolated by affinity chromatography, using bag cell egg-laying hormone (ELH) as the bound ligand, and partially purified and characterized by gel electrophoresis. The protein has an apparent molecular weight of 52 kDa and consists of two disulfide-linked subunits of about 30 kDa each. The protein is glycosylated and has an acidic pI. Approximately 10–15 μg of this protein can be isolated from a single ovotestis, representing less than 1% of the total protein in the gonad; but the protein could not be detected in buccal mass or body wall, tissues which do not have apparent response to ELH. Antibodies generated against this ELH-binding protein (ELHBP) were used to localize sites in the ovotestis which might contain this molecule and thus represent targets for egg-laying hormone. Immunocytochemical results indicate that the oocytes are a rich source of this protein, since their cytoplasm was the only detectable site of immunoreactivity. Whether this binding protein represents an egg-laying hormone receptor is uncertain, but its prevalence in oocytes suggests that ELH plays a signaling role on these gametes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00193520
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  • 36
    Digitale Medien
    Digitale Medien
    Multivariate exploratory data analysis in chemical industry (1991)
    Springer
    Microchimica acta 104 (1991), S. 467-482 
    Details
    ISSN: 1436-5073
    Schlagwort(e): prediction ; stability ; multivariate methods ; graphical analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Sizeable data bases are now being routinely generated in a variety of contexts in chemical industry. Statistical investigations of such data bases are aimed both at initially uncovering structure and eventually proposing models, in particular for predicting product quality by the mix or characteristics of the chemical compounds. “Online Multivariate Exploratory Graphical Analysis” (OMEGA) stands for a structured exploratory study of the relationships in a multivariate data set, where, rather than testing for one specific property, as many clues as possible for interesting structures are searched for by different dimension reductions and succeeding interactive graphical analyses. The stability of the projections obtained by the different dimension reduction methods is assessed by simulation producing graphical displays particularly supporting the identification of influential points. The variation of the predictions obtained by the different dimension reduction methods is assessed by cross-validation delivering misclassification rates or cross-validated R2 values. The interpretation of the new coordinates corresponding to dimension reduction is supported by loading simplifications and graphical displays for judging its adequacy. The OMEGA strategy has been found to be an effective tool for routine searching for structure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01245532
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  • 37
    Digitale Medien
    Digitale Medien
    Nonabelian K-theory: The nilpotent class of K 1 and general stability (1991)
    Springer
    K-Theory 4 (1991), S. 363-397 
    Details
    ISSN: 1573-0514
    Schlagwort(e): Nonabelian K 1 ; noncommutative homotopy ; general linear group ; superspecial linear groups ; descending central series ; stability ; relative normal subgroups ; nilpotent sandwich classifications ; quasi-finite algebras
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract A functorial filtration GL n =S−1L n $$ \supseteq$$ S0L n $$ \supseteq$$ ⋯ $$ \supseteq$$ S i L n $$ \supseteq$$ ⋯ $$ \supseteq$$ E n of the general linear group GL n, n ⩾ 3, is defined and it is shown for any algebra A, which is a direct limit of module finite algebras, that S−1 L n (A)/S0L n (A) is abelian, that S0L n (A) $$ \supseteq$$ S1L n (A) $$ \supseteq$$ ⋯ is a descending central series, and that S i L n (A) = E n(A) whenever i ⩾ the Bass-Serre dimension of A. In particular, the K-functors k 1 S i L n =S i L n /E n are nilpotent for all i ⩾ 0 over algebras of finite Bass-Serre dimension. Furthermore, without dimension assumptions, the canonical homomorphism S i L n (A)/S i+1 L n (A)→S i L n+ 1(A)/S i+1 L n + 1 (A) is injective whenever n ⩾ i + 3, so that one has stability results without stability conditions, and if A is commutative then S0L n (A) agrees with the special linear group SL n (A), so that the functor S0L n generalizes the functor SL n to noncommutative rings. Applying the above to subgroups H of GL n (A), which are normalized by E n(A), one obtains that each is contained in a sandwich GL′ n (A, ρ) $$ \supseteq$$ H $$ \supseteq$$ E n(A, ρ) for a unique two-sided ideal ρ of A and there is a descending S0L n (A)-central series GL′ n (A, ρ) $$ \supseteq$$ S0L n (A, ρ) $$ \supseteq$$ S1L n (A, ρ) $$ \supseteq$$ ⋯ $$ \supseteq$$ S i L n (A, ρ) $$ \supseteq$$ ⋯ $$ \supseteq$$ E n(A, ρ) such that S i L n (A, ρ)=E n(A, ρ) whenever i ⩾ Bass-Serre dimension of A.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00533991
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  • 38
    Digitale Medien
    Digitale Medien
    Representing homology classes by locally flat 2-spheres (1993)
    Springer
    K-Theory 7 (1993), S. 333-367 
    Details
    ISSN: 1573-0514
    Schlagwort(e): Locally flat embedding ; pointed Hermitian module ; splitting ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract We prove an existence result for topologically locally flat embeddings of 2-spheres in simply connected 4-manifolds. This topological result is deduced from a splitting theorem for pointed Hermitian modules over a cyclic group ring. A stability result for such modules is also proved. This applies to the isotopy classification of locally flat embeddings.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00962053
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  • 39
    Digitale Medien
    Digitale Medien
    Effect of the incubation conditions on the production of patulin by Penicillium griseofulvum isolated from wheat (1991)
    Springer
    Mycopathologia 115 (1991), S. 163-168 
    Details
    ISSN: 1573-0832
    Schlagwort(e): Penicillium griseofulvum ; patulin ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Sixty-four wheat samples from Spanish flour factories were screened for patulin and patulin-producing moulds. None of them was found to contain any patulin, whereas samples experimentally contaminated with this toxin proved it to be highly unstable. On the other hand, Penicillium griseofulvum was the only in vitro patulin-producing species found (19 samples). Mould growth in the samples was investigated by using yeast-sucrose medium (YES) and high-performance liquid chromatography (HPLC) to measure the amounts of toxin produced during 40 day's incubation at 20 and 28°C. The highest yield rate of patulin was obtained between the 20th and 30th day of incubation; such a rate, however, was very low throughout the vigorous growth phase, during the first 20 days of incubation. The more appropriate temperature for incubation and patulin production was 28 °C. We also investigated the influence of other incubation conditions in the yield and found stationary dark cultures to be more efficient that shaken or fermentation cultures in YES medium. The best patulin yield achieved was 11.9 mg in the culture broth and 6.3 mg in the mycelium from 100 ml of medium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00462220
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  • 40
    Digitale Medien
    Digitale Medien
    The effect of level of application on the residual value of superphosphate on a sandy soil in south-western Australia (1991)
    Springer
    Nutrient cycling in agroecosystems 29 (1991), S. 163-172 
    Details
    ISSN: 1573-0867
    Schlagwort(e): Superphosphate ; residual value ; sandy soil ; leaching of phosphorus ; lupins ; barley ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract In a field experiment on deep, yellow, sandy soil near Badgingarra, Western Australia, the residual value of superphosphate applied one and two years previously was measured relative to freshly-applied superphosphate using yields of narrow-leafed lupin (Lupinus angustifolius), barley and wheat. In addition, soil samples were collected for measurement of bicarbonate-extractable soil P. This was also used to estimate the residual value of the superphosphate. For lupins and wheat, and for bicarbonate-extractable soil P, the residual value decreased with increasing level of application. For barley grain, the residual value was not significantly affected by the level of application. The decrease in residual value of superphosphate with increasing level of application is attributed to increased leaching of applied phosphorus (P) down the profile of the sandy soils as the level of application increases. This may reduce subsequent plant yields due to the delay in seedling roots reaching the P in the soil during the crucial early stages of plant growth. For lupins, the relationship between yield and the level of superphosphate applied was markedly sigmoidal. The relationship for wheat and barley was exponential. Consequently, at suboptimal levels of P application, lupins required about two to three times more P than wheat or barley to produce the same yield. However, lupins required less P to achieve near-maximum yield.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01048956
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  • 41
    Digitale Medien
    Digitale Medien
    Stability regions of Schur andG-stable polynomials (1993)
    Springer
    Multidimensional systems and signal processing 4 (1993), S. 91-101 
    Details
    ISSN: 1573-0824
    Schlagwort(e): Bilinear transformation ; polynomial ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract The paper presents a unified approach to calculation, for a given, nominal,G-stable polynomial, a corresponding stability region in the space of perturbed coefficients
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00986008
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  • 42
    Digitale Medien
    Digitale Medien
    Stability determination of two-dimensional discrete-time systems (1993)
    Springer
    Multidimensional systems and signal processing 4 (1993), S. 331-354 
    Details
    ISSN: 1573-0824
    Schlagwort(e): two-dimensional discrete-time systems ; two-dimensional digital filters ; bivariate polynomials ; stability ; Bistritz tabular form ; Jury tabular form ; Schur-Cohn minors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Abstract In determining root distribution of univariate polynomials with real or complex-valued coefficients, the Bistritz tabular form offers a significant computational advantage. Stability studies of two-dimensional (2-D) discrete-time systems involve univariate polynomials possessing parameter-dependent coefficients, where the parameter takes values on the unit circle in the complex plane. This paper investigates the application of Bistritz tabular form in determining stability of 2-D discrete-time systems, and for this purpose we present two algorithms. Both algorithms utilize a recent result that has established the relationship between Schur-Cohn minors and the entries of the Bistritz tabular form corresponding to a given polynomial. A comparison between the use of the modified Jury table and the Bistritz table in stability checking of 2-D discrete-time systems is also presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00989650
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  • 43
    Digitale Medien
    Digitale Medien
    Acid-base equilibrium—A thermodynamic study of formation and stability of the Bi-2223 phase (1993)
    Springer
    Journal of superconductivity 6 (1993), S. 55-57 
    Details
    ISSN: 1572-9605
    Schlagwort(e): Superconductivity ; Bi-2223 ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Elektrotechnik, Elektronik, Nachrichtentechnik , Physik
    Notizen: Abstract A general acid-base equilibrium theory was proposed to explain the formation and stability of the Bi-2223 phase based on the Lewis acid-base theory, and principle of metallurgical physical chemistry. The acid-base nature of oxide was defined according to the electrostatic force between cation and oxygen anion. A series of experimental facts were systematically explained based on the theory: substitution of Bi for Ca in. the Pb-free 2223 phase, and the effect of substitution of the high-valent cation for Bi3+; oxygen-pressure atmosphere, and the heat-schocking technique on the formation and stability of the 2223 phase.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00618506
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  • 44
    Digitale Medien
    Digitale Medien
    Polymorphism in the giant cocoa termite,Neotermes papua (Desneux) (1991)
    Springer
    Insectes sociaux 38 (1991), S. 263-272 
    Details
    ISSN: 1420-9098
    Schlagwort(e): Isoptera ; Kalotermitidae ; Neotermes papua ; termites ; caste differentiation ; division of labour ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The direct development ofNeotermes papua (Isoptera: Kalotermitidae) comprises four larval and three nymphal instars before the alate. The first five instars can be easily characterized. The second stage nymphs come morphologically close to the pseudergates, characterized by reduced wing buds. These nymphs can moult stationarily, i.e. with little morphological change, or to presoldiers, or proceed to the alate via the third nymphal stage. Pseudergates originate through a late and reversible deviation from the straight development to the alate. Presoldiers may derive from several stages, up to the last nymphal one; their production is subject to an inhibition by extant soldiers. This developmental schema is congruent with those described in other Kalotermitidae and the Termopsidae. By pinpointing the existence of a large pool of pluripotent individuals, in which the penultimate nymphal stage mingles with pseudergates, the present study also reveals a great similarity betweenNeotermes andProrhinotermes, and suggests that this developmental schema might be generally applicable to termites devoid of a permanent worker caste.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01314912
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  • 45
    Digitale Medien
    Digitale Medien
    Molecular cloning and sequencing of 18S rDNA gene fragments from six different ant species (1993)
    Springer
    Insectes sociaux 40 (1993), S. 325-335 
    Details
    ISSN: 1420-9098
    Schlagwort(e): Formicidae ; social parasitism ; PCR ; 18 S ribosomal RNA ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The evolutionary relationship between socially parasitic ants and their hosts is still an unsolved problem. We have compared a 1.2 kb sequence of the 18 S ribosomal RNA genes of the parasitic antsDoronomyrmex kutteri, Harpagoxenus sublaevis andChalepoxenus muellerianus to the sequence of the host speciesLeptothorax acervorum andL. recedens (all subfamily Myrmicinae, tribe Leptothoracini) and to an out-group antCamponotus ligniperda (Formicinae). We found that parasitic species and the host species and alsoCamponotus ligniperda differ at less than 1% of the base positions of the 1.2 kb segment of the 18S rRNA gene. The sequences showed 80.3% identity to the 18 S ribosomal RNA genes of the beetleTenebrio molitor and only 66.5% to that of the dipteranDrosophila melanogaster.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01242369
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  • 46
    Digitale Medien
    Digitale Medien
    Chemical defense of a primitive Australian bombardier beetle (Carabidae):Mystropomus regularis (1991)
    Springer
    Chemoecology 2 (1991), S. 29-34 
    Details
    ISSN: 1423-0445
    Schlagwort(e): defensive secretion ; hot secretion ; elytral flanges ; evolution ; benzoquinones ; hydrocarbons ; bombardier beetle ; Coleoptera ; Carabidae ; Paussinae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The Australian bombardier beetle,Mystropomus regularis, sprays a mixture of quinones (1,4-benzoquinone, 2-methyl-1,4-benzoquinone, 2-ethyl-1,4-benzoquinone) and hydrocarbons (principallyn-pentadecane). The defensive fluid ist generated explosively in two-chambered glands, and is ejected audibly and hot (maximal recorded temperature = 59°C).Mystropomus is a member of the paussoid lineage of bombardiers. In common with other members of the group, it has a pair of elytral flanges (flanges of Coanda), associated with the gland openings, that serve as launching guides for anteriorly-aimed ejections of spray. It is argued thatMystropomus may be the least derived of flanged paussoids, and the closest living relative of the most primitive of extant bombardiers (Metriini).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01240663
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  • 47
    Digitale Medien
    Digitale Medien
    Implications of toxins in the ecology and evolution of plant pathogenic microorganisms: Bacteria (1991)
    Springer
    Cellular and molecular life sciences 47 (1991), S. 791-803 
    Details
    ISSN: 1420-9071
    Schlagwort(e): Phytotoxins ; ecology ; phylogeny ; evolution ; biosynthesis ; coronatine ; phaseolotoxin ; rhizobitoxine ; syringomycin ; syringotoxin ; syringostatin ; tabtoxin ; tagetitoxin ; tropolone ; fireblight toxin ; thaxtomin ; 3-methylthiopropionic acid ; carboxylic acids ; Pseudomonas ; Xanthomonas ; Xanthomonas ; Streptomyces ; Erwinia ; Bradyrhizobium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract This review attempts to rationalise what is known about bacterial phytotoxins and associate it with the ecology and possible evolution of the producing organisms. Study of non-toxin producing variants gives insight into the ecological role of the toxin. Elucidation of chemical structures of phytotoxins has shown that many exist as families of analogous compounds. Studies on the variation of chemical structures and how they are distributed across species and genera can lead to development of hypotheses on evolutionary relationships. Knowledge on biosynthetic pathways to tosins allows recognition of specific enzymatic steps involved in developing the characteristic features of the structures. Phytotoxins often have a potent biochemical activity, and in some cases the producing organism has associated mechanisms to prevent action of the toxin upon itself; in such cases toxigenesis is clearly not a chance event. The various aspects of bacterial toxigenesis indicate that bacterial phytotoxins are special secondary metabolic products that play beneficial roles to the producing organisms in their various ecological niches.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01922459
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  • 48
    Digitale Medien
    Digitale Medien
    A segment of rye chromosome 1 enhances growth and embryogenesis of calli derived from immature embryos of wheat (1991)
    Springer
    Plant cell reports 10 (1991), S. 148-151 
    Details
    ISSN: 1432-203X
    Schlagwort(e): wheat ; rye ; embryogenesis ; growth ; tissue culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The influence of the short arm of rye chromosome 1 (1RS) from Secale cereale var. Imperial on the growth and differentiation of callus cultures from wheat Triticum aestivum var. Chinese Spring immature embryos was analysed. This chromosome arm was found to stimulate both embryogenesis and the rate of growth of calli. Recombinant lines carrying segments of 1RS were used to delineate the regions of 1RS responsible for the tissue culture effects. The enhancement of embryogenesis and the stimulation of growth were shown to be associated with two distinct genetic regions of the chromosome arm; the former is located between the centromere and the Sec 1 locus, while the latter is situated in the immediate vicinity of the Sec 1 locus.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00232047
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  • 49
    Digitale Medien
    Digitale Medien
    Circadian photoreception in the retinally degenerate mouse (rd/rd) (1991)
    Springer
    Journal of comparative physiology 169 (1991), S. 39-50 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Photoreception ; Retinally degenerate ; Mouse ; Circadian ; Rods ; Cones ; 11-cis retinaldehyde ; Immunocytochemistry ; HPLC
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary We have examined the effects of light on circadian locomotor rhythms in retinally degenerate mice (C57BL/6J mice homozygous for the rd allele: rd/rd). The sensitivity of circadian photoreception in these mice was determined by varying the irradiance of a 15 min light pulse (515 nm) given at circadian time 16 and meauring the magnitude of the phase shift of the locomotor rhythm. Experiments were performed on animals 80 days of age. Despite the loss of visual photoreceptors in the rd/rd retina, animals showed circadian responses to light that were indistinguishable from mice with normal retinas (rd/+ and +/+). While no photoreceptor outersegments were identified in the retina of rd/rd animals (80–100 days of age), we did identify a small number of perikarya that were immunoreactive for cone opsins, and even fewer cells that contained rod opsin. Using HPLC, we demonstrated the presence and photoisomerization of the rhodopsin chromophore 11-cis retinaldehyde. The rd/rd retinas contained about 2% of 11-cis retinaldehyde found in +/+ retinas. We have yet to determine whether the opsin immunoreactive perikarya or some other unidentified cell type mediate circadian light detection in the rd/rd retina.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00198171
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  • 50
    Digitale Medien
    Digitale Medien
    Attractors and transients for a perturbed periodic KdV equation: A nonlinear spectral analysis (1993)
    Springer
    Journal of nonlinear science 3 (1993), S. 477-539 
    Details
    ISSN: 1432-1467
    Schlagwort(e): nearly integrable systems ; spectral transform ; attractors ; traveling waves ; stability ; numerical methods
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Summary In this paper we rigorously show the existence and smoothness inε of traveling wave solutions to a periodic Korteweg-deVries equation with a Kuramoto-Sivashinsky-type perturbation for sufficiently small values of the perturbation parameterε. The shape and the spectral transforms of these traveling waves are calculated perturbatively to first order. A linear stability theory using squared eigenfunction bases related to the spectral theory of the KdV equation is proposed and carried out numerically. Finally, the inverse spectral transform is used to study the transient and asymptotic stages of the dynamics of the solutions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02429875
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  • 51
    Digitale Medien
    Digitale Medien
    Analysis of stable two-dimensional patterns in contractile cytogel (1991)
    Springer
    Journal of nonlinear science 1 (1991), S. 289-311 
    Details
    ISSN: 1432-1467
    Schlagwort(e): cytogel ; mechanochemical ; two-dimensional patterns ; cellular differentiation ; pattern formation ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Summary Contractile actomyosin systems play a central role in the generation of intracellular patterns. Models for pattern formation have benefited greatly from the application of mechanochemical theory. However, investigations of the patterns have been primarily qualitative in nature; the two-dimensional nature of the evolving patterns has not yet been addressed mathematically, nor has the evolution of stable heterogeneous steady-state solutions. We consider these issues, supporting our analytical predictions with numerical simulations in one and two spatial dimensions. We show how, for certain gels, the two and three-dimensional tensor equation which describes a balance of forces can be reduced to a reaction-diffusion equation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01238816
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  • 52
    Digitale Medien
    Digitale Medien
    Computing a closest bifurcation instability in multidimensional parameter space (1993)
    Springer
    Journal of nonlinear science 3 (1993), S. 307-327 
    Details
    ISSN: 1432-1467
    Schlagwort(e): bifurcation ; saddle node ; Hopf ; stability ; robustness ; optimization ; numerical methods ; transcritical ; pitchfork ; extended systems
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik , Physik
    Notizen: Summary Engineering and physical systems are often modeled as nonlinear differential equations with a vector λ of parameters and operated at a stable equilibrium. However, as the parameters λ vary from some nominal value λ0, the stability of the equilibrium can be lost in a saddle-node or Hopf bifurcation. The spatial relation in parameter space of λ0 to the critical set of parameters at which the stable equilibrium bifurcates determines the robustness of the system stability to parameter variations and is important in applications. We propose computing a parameter vector λ* at which the stable equilibrium bifurcates which is locally closest in parameter space to the nominal parameters λ0. Iterative and direct methods for computing these locally closest bifurcations are described. The methods are extensions of standard, one-parameter methods of computing bifurcations and are based on formulas for the normal vector to hypersurfaces of the bifurcation set. Conditions on the hypersurface curvature are given to ensure the local convergence of the iterative method and the regularity of solutions of the direct method. Formulas are derived for the curvature of the saddle node bifurcation set. The methods are extended to transcritical and pitchfork bifurcations and parametrized maps, and the sensitivity to λ0 of the distance to a closest bifurcation is derived. The application of the methods is illustrated by computing the proximity to the closest voltage collapse instability of a simple electric power system.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02429868
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  • 53
    Digitale Medien
    Digitale Medien
    Estimates for norms of matrix-valued and operator-valued functions and some of their applications (1993)
    Springer
    Acta applicandae mathematicae 32 (1993), S. 59-88 
    Details
    ISSN: 1572-9036
    Schlagwort(e): 47A56 ; 47A55 ; 15A54 ; 35A30 ; 34A30 ; Operator-valued functions ; matrices ; nonself-adjoint operators ; spectrum perturbation ; eigenvalues ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Mathematik
    Notizen: Abstract A survey is presented of estimates for a norm of matrix-valued and operator-valued functions obtained by the author. These estimates improve the Gel'fand-Shilov estimate for regular functions of matrices and Carleman's estimates for resolvents of matrices and compact operators. From the estimates for resolvents, the well-known result for spectrum perturbations of self-adjoint operators is extended to quasi-Hermitian operators. In addition, the classical Schur and Brown's inequalities for eigenvalues of matrices are improved. From estimates for the exponential function (semigroups), bounds for solution norms of nonlinear differential equations are derived. These bounds give the stability criteria which make it possible to avoid the construction of Lyapunov functions in appropriate situations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00992083
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  • 54
    Digitale Medien
    Digitale Medien
    A rice (Oryza sativa L.) cDNA encodes a protein sequence homologous to the eukaryotic ribosomal 5S RNA-binding protein (1993)
    Springer
    Plant molecular biology 23 (1993), S. 409-413 
    Details
    ISSN: 1573-5028
    Schlagwort(e): cDNA ; cloning ; rice ; L5 ; ribosomal 5 S RNA-binding protein ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A rice (Oryza sativa L.) cDNA clone coding for the cytoplasmic ribosomal protein L5, which associates with 5 S rRNA for ribosome assembly, was cloned and its nucleotide sequence was determined. The primary structure of rice L5, deduced from the nucleotide sequence, contains 294 amino acids and has intriguing features some of which are also conserved in other eucaryotic homologues. These include: four clusters of basic amino acids, one of which may serve as a nucleolar localization signal; three repeated amino acid sequences; the conservation of glycine residues. This protein was identified as the nuclear-encoded cytoplasmic ribosomal protein L5 of rice by sequence similarity to other eucaryotic ribosomal 5 S RNA-binding proteins of rat, chicken, Xenopus laevis, and Saccharomyces cerevisiae. Rice L5 shares 51 to 62% amino acid sequence identity with the homologues. A group of ribosomal proteins from archaebacteria including Methanococcus vanniellii L18 and Halobacterium cutirubrum L13, which are known to be associated with 5 S rRNA, also related to rice L5 and the other eucaryotic counterparts, suggesting an evolutionary relationship in these ribosomal 5 S RNA-binding proteins.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00029016
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  • 55
    Digitale Medien
    Digitale Medien
    Plant aldolase: cDNA and deduced amino-acid sequences of the chloroplast and cytosol enzyme from spinach (1993)
    Springer
    Plant molecular biology 21 (1993), S. 331-340 
    Details
    ISSN: 1573-5028
    Schlagwort(e): cDNA sequences ; evolution ; fructose-1,6-bisphosphate aldolase ; Spinacia oleracea ; transit peptide
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We report the sequences of full-length cDNAs for the nuclear genes encoding the chloroplastic and cytosolic fructose-1,6-bisphosphate aldolase (EC 4.1.2.13) from spinach. A comparison of the deduced amino-acid sequences with one another and with published cytosolic aldolase sequences of other plants revealed that the two enzymes from spinach share only 54% homology on their amino acid level whereas the homology of the cytosolic enzyme of spinach with the known sequences of cytosolic aldolases of maize, rice and Arabidopsis range from 67 to 92%. The sequence of the chloroplastic enzyme includes a stroma-targeting N-terminal transit peptide of 46 amino acid residues for import into the chloroplast. The transit peptide exhibits essential features similar to other chloroplast transit peptides. Southern blot analysis implies that both spinach enzymes are encoded by single genes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00019948
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  • 56
    Digitale Medien
    Digitale Medien
    Sorghum phosphoenolpyruvate carboxylase gene family: structure, function and molecular evolution (1993)
    Springer
    Plant molecular biology 21 (1993), S. 487-502 
    Details
    ISSN: 1573-5028
    Schlagwort(e): C4 metabolism ; evolution ; GC content ; gene family ; PEPC ; Sorghum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Although housekeeping functions have been shown for the phosphoenolpyruvate carboxylase (EC 4.1.1.31, PEPC) in plants and in prokaryotes, PEPC is mainly known for its specific role in the primary photosynthetic CO2 fixation in C4 and CAM plants. We have shown that in Sorghum, a monocotyledonous C4 plant, the enzyme is encoded in the nucleus by a small multigene family. Here we report the entire nucleotide sequence (7.5 kb) of the third member (CP21) that completes the structure of the Sorghum PEPC gene family. Nucleotide composition, CpG islands and GC content of the three Sorghum PEPC genes are analysed with respect to their possible implications in the regulation of expression. A study of structure/function and phylogenetic relationships based on the compilation of all PEPC sequences known so far is presented. Data demonstrate that (1) the different forms of plant PEPC have very similar primary structures, functional and regulatory properties, (2) neither apparent amino acid sequences nor phylogenetic relationships are specific for the C4 and CAM PEPCs and (3) expression of the different genes coding for the Sorghum PEPC isoenzymes is differently regulated (i.e. by light, nitrogen source) in a spatial and temporal manner. These results suggest that the main distinguishing feature between plant PEPCs is to be found at the level of genes expression rather than in their primary structure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00028806
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  • 57
    Digitale Medien
    Digitale Medien
    Destabilization of pea lectin by substitution of a single amino acid in a surface loop (1993)
    Springer
    Plant molecular biology 22 (1993), S. 1039-1046 
    Details
    ISSN: 1573-5028
    Schlagwort(e): antinutritional factor ; pea lectin ; site-directed mutagenesis ; stability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Legume lectins are considered to be antinutritional factors (ANF) in the animal feeding industry. Inactivation of ANF is an important element in processing of food. In our study on the stability ofPisum sativum L. lectin (PSL), a conserved hydrophobic amino acid (Val103) in a surface loop was replaced with alanine. The mutant lectin, PSL V103A, showed a decrease in unfolding temperature (T m ) by some 10 °C in comparison with wild-type (wt) PSL, and the denaturation energy (ΔH) is only about 55% of that of wt PSL. Replacement of an adjacent amino acid (Phe104) with alanine did not result in a significant difference in stability in comparison with wt PSL. Both mutations did not change the sugarbinding properties of the lectin, as compared with wt PSL and with PSL from pea seeds, at ambient temperatures. The double mutant, PSL V103A/F104A, was produced inEscherichia coli, but could not be isolated in an active (i.e. sugar-binding) form. Interestingly, the mutation in PSL V103A reversibly affected sugar-binding at 37 °C, as judged from haemagglutination assays. These results open the possibility of production of lectins that are activein planta at ambient temperatures, but are inactive and possibly non-toxic at 37 °C in the intestines of mammals.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00028976
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  • 58
    Digitale Medien
    Digitale Medien
    Single-seed PCR of LMW glutenin genes to distinguish between durum wheat cultivars with good and poor technological properties (1993)
    Springer
    Plant molecular biology 22 (1993), S. 1173-1176 
    Details
    ISSN: 1573-5028
    Schlagwort(e): polymerase chain reaction ; LMW glutenin genes ; wheat ; quality
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Polymerase chain reaction (PCR) was used to amplify low-molecular-weight (LMW) glutenin sequences from genomic DNA extracted from a single germinating seed of several durum wheat genotypes. Electrophoretic analysis of PCR reactions showed the presence of amplified products characteristic of durum wheat cultivars with good and poor technological properties. This PCR-based approach is proposed as a very efficient and safe alternative to standard procedures for selecting durum wheat genotypes with good qualitative characteristics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00028988
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  • 59
    Digitale Medien
    Digitale Medien
    Genomic rearrangement of the α-globin gene complex during mammalian evolution (1993)
    Springer
    Biochemical genetics 31 (1993), S. 473-484 
    Details
    ISSN: 1573-4927
    Schlagwort(e): hydroxyacyl glutathione hydrolase (glyoxalase II) ; chromosome mapping ; evolution ; Mus musculus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract In man, the gene for hydroxyacyl glutathione hydrolase (HAGH; glyoxalase II) is closely linked to the α-globin locus (HBα) on Chromosome 16. HAGH polymorphism in the mouse has now enabled the mapping of the murine homologue. Deletion mapping, congenic strain studies, and characterization of 41 recombinant inbred strains establish that the mouseHagh locus lies very close to the α-globin pseudogene (Hba-ps4) in the vicinity of the major histocompatibility locus (H-2) on chromosome 17. Several other loci have been identified previously that are also closely linked to the human α-globin locus but near the α-globin pseudogeneHba-ps4 in the mouse. These linkage relationships suggest that during the evolution of mice a translocation occurred that subdivided the α-globin locus, leaving one inactive α-globin gene still associated with theHagh locus and linked sequences, while moving and inserting the active α-globin locus and all distal sequences into an internal location on another autosome, the predecessor to mouse chromosome 11.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02426879
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  • 60
    Digitale Medien
    Digitale Medien
    ADrosophila homologue of theSchizosaccharomyces pombe act2 gene (1993)
    Springer
    Biochemical genetics 31 (1993), S. 329-341 
    Details
    ISSN: 1573-4927
    Schlagwort(e): actin superfamily ; Drosophila genetics ; ATPase domain ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Diverse proteins that are 35% to 55% identical to actins have been discovered recently in yeasts, nematodes, and vertebrates. In order to study these proteins systematically and relate their functions to those of conventional actins, we are isolating the corresponding genes from the genetically tractable eukaryote,Drosophila melanogaster. Here we report the isolation and partial characterization of aDrosophila homologue of theSchizosaccharomyces pombe act2 gene. Degenerate oligonucleotide primers specifying peptides that are highly conserved within the actin protein superfamily were used in conjunction with polymerase chain reaction (PCR) to amplify a portion of theDrosophila gene that we have namedactr66B. The corresponding full-length cDNA sequence encodes a protein of 418 residues that is 65% identical to the product of theS. pombe act2 gene, 80% identical to the bovineact2 homologue, but only 48% identical to the principalDrosophila cytoplasmic actin encoded by theAct5C actin gene. Alignment of the yeast, bovine, andDrosophila actin-related proteins shows that they have four peptide insertions, relative to conventional actins, three of which are well placed to modify actin polymerization and one that is likely to perturb the binding of myosin. Locations of two of the fiveactr66B introns are conserved betweenDrosophila and yeast genes, further attesting that they evolved from a common ancestor and are likely to encode proteins having similar functions. We demonstrate that theDrosophila gene is located on the left arm of chromosome 3, within subdivision 66B. Finally, we show by RNA blot-hybridization that the gene is expressed at low levels, relative to conventional nonmuscle actin, in all developmental stages. From these and other observations we infer that the actr66B protein is a minor component of all cells, perhaps serving to modify the polymerization, structure, and dynamic behavior of actin filaments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00553175
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  • 61
    Digitale Medien
    Digitale Medien
    Genomic rearrangement of the α-globin gene complex during mammalian evolution (1993)
    Springer
    Biochemical genetics 31 (1993), S. 473-484 
    Details
    ISSN: 1573-4927
    Schlagwort(e): hydroxyacyl glutathione hydrolase (glyoxalase II) ; chromosome mapping ; evolution ; Mus musculus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract In man, the gene for hydroxyacyl glutathione hydrolase (HAGH; glyoxalase II) is closely linked to the α-globin locus (HBα) on Chromosome 16. HAGH polymorphism in the mouse has now enabled the mapping of the murine homologue. Deletion mapping, congenic strain studies, and characterization of 41 recombinant inbred strains establish that the mouseHagh locus lies very close to the α-globin pseudogene (Hba-ps4) in the vicinity of the major histocompatibility locus (H-2) on chromosome 17. Several other loci have been identified previously that are also closely linked to the human α-globin locus but near the α-globin pseudogeneHba-ps4 in the mouse. These linkage relationships suggest that during the evolution of mice a translocation occurred that subdivided the α-globin locus, leaving one inactive α-globin gene still associated with theHagh locus and linked sequences, while moving and inserting the active α-globin locus and all distal sequences into an internal location on another autosome, the predecessor to mouse chromosome 11.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00554074
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  • 62
    Digitale Medien
    Digitale Medien
    ADrosophila homologue of theSchizosaccharomyces pombe act2 gene (1993)
    Springer
    Biochemical genetics 31 (1993), S. 329-341 
    Details
    ISSN: 1573-4927
    Schlagwort(e): actin superfamily ; Drosophila genetics ; ATPase domain ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Diverse proteins that are 35% to 55% identical to actins have been discovered recently in yeasts, nematodes, and vertebrates. In order to study these proteins systematically and relate their functions to those of conventional actins, we are isolating the corresponding genes from the genetically tractable eukaryote,Drosophila melanogaster. Here we report the isolation and partial characterization of aDrosophila homologue of theSchizosaccharomyces pombe act2 gene. Degenerate oligonucleotide primers specifying peptides that are highly conserved within the actin protein superfamily were used in conjunction with polymerase chain reaction (PCR) to amplify a portion of theDrosophila gene that we have namedactr66B. The corresponding full-length cDNA sequence encodes a protein of 418 residues that is 65% identical to the product of theS. pombe act2 gene, 80% identical to the bovineact2 homologue, but only 48% identical to the principalDrosophila cytoplasmic actin encoded by theAct5C actin gene. Alignment of the yeast, bovine, andDrosophila actin-related proteins shows that they have four peptide insertions, relative to conventional actins, three of which are well placed to modify actin polymerization and one that is likely to perturb the binding of myosin. Locations of two of the fiveactr66B introns are conserved betweenDrosophila and yeast genes, further attesting that they evolved from a common ancestor and are likely to encode proteins having similar functions. We demonstrate that theDrosophila gene is located on the left arm of chromosome 3, within subdivision 66B. Finally, we show by RNA blot-hybridization that the gene is expressed at low levels, relative to conventional nonmuscle actin, in all developmental stages. From these and other observations we infer that the actr66B protein is a minor component of all cells, perhaps serving to modify the polymerization, structure, and dynamic behavior of actin filaments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02401827
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  • 63
    Digitale Medien
    Digitale Medien
    The amino acid sequence of a protein from wheat kernel closely related to proteins involved in the mechanisms of plant defence (1993)
    Springer
    The protein journal 12 (1993), S. 379-386 
    Details
    ISSN: 1573-4943
    Schlagwort(e): Amino acid sequence ; wheat ; wounding ; plant defence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The amino acid sequence of wheatwin1, a monomeric protein of 125 residues isolated from wheat kernel (variety S. Pastore), is reported. Wheatwin1 is highly homologous (95%) to barwin, a protein from barley seed, which was shown to be related to the C-terminal domain of two proteins encoded by the wound-induced geneswin1 andwin2 in potato and to a protein encoded by the same domain of the hevein gene (hev1) in rubber tree. Similarly to barwin, wheatwin1 contains six cysteine residues all linked in disulfide bridges and the N-terminal residue is pyroglutamate. Moreover, structural studies performed on wheatwin1 andwin1 protein by predictive methods demonstrated that these proteins and barwin are closely related in the secondary structure also. The high level of homology found with the product ofwin1,win2, andhev1 genes strongly suggests that barwin and wheatwin1 play a common role in the mechanism of plant defence.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01025037
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  • 64
    Digitale Medien
    Digitale Medien
    Sequence of the iaa and ipt region of different Agrobacterium tumefaciens biotype III octopine strains: reconstruction of octopine Ti plasmid evolution (1991)
    Springer
    Plant molecular biology 16 (1991), S. 601-614 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Agrobacterium tumefaciens ; Ti plasmid ; evolution ; IS elements ; host range
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The TA regions of biotype III octopine/cucumopine (OC) Ti plasmids are closely related to the TL region of the biotype I octopine Ti plasmids pTiAch5 and pTi15955. Sequence analysis shows that the limited and wide host range biotype III OC TA regions are derived from a common ancestor structure which lacked the 6a gene found in the biotype I octopine TL region. The TA region of the wide host range OC Ti plasmids has conserved most of the original TL-like structure. In most wide host range OC isolates the TA-iaaH gene is inactivated by the insertion of an IS866 element. However, the TA region of the wide host range isolate Hm1 carries an intact TA-iaaH gene. This gene encodes a biologically active product, as shown by root induction tests and indole-3-acetic acid measurements. The limited host range OC Ti plasmids pTiAB3 and pTiAg57 have shorter TA regions which are derived from a wide host range TA region. The AB3 type arose by an IS868-mediated, internal TA region deletion which removed the iaa genes and part of the ipt gene and left a copy of IS868 at the position of the deleted fragment. The pTiAB3 iaa/ipt deletion was followed by insertion of a second IS element, IS869, immediately 3′ of the ipt gene. pTiAg57 underwent the same iaa-ipt deletion as pTiAB3, but lacks the IS868 and IS869 elements. Analysis of the various TA region structures provides a detailed insight into the evolution of the biotype III OC strains.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00023425
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  • 65
    Digitale Medien
    Digitale Medien
    Characterization of members of a pseudogene subfamily of the wheat α-gliadin storage protein genes (1991)
    Springer
    Plant molecular biology 16 (1991), S. 335-337 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Triticum ; wheat ; endosperm ; gliadin ; pseudogene ; duplication ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00020565
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  • 66
    Digitale Medien
    Digitale Medien
    Wheat ubiquitin gene exhibits a conserved protein coding region and a diverged 3′ non-coding region (1991)
    Springer
    Plant molecular biology 16 (1991), S. 907-908 
    Details
    ISSN: 1573-5028
    Schlagwort(e): ubiquitin ; wheat ; heat shock protein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00015082
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  • 67
    Digitale Medien
    Digitale Medien
    Site-directed mutagenesis and expression inEscherichia coli of WMAI-1, a wheat monomeric inhibitor of insect α-amylase (1991)
    Springer
    Plant molecular biology 17 (1991), S. 1005-1011 
    Details
    ISSN: 1573-5028
    Schlagwort(e): α-amylase inhibitor ; expression inE. coli ; glycosylation versus activity ; insect α-amylase ; mutagenesis ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The wheat monomeric inhibitor WMAI-1 (syn. 0.28) produced inEscherichia coli using the pT7-7 expression ventor has the correct N-terminal sequence and the same electrophoretic mobility and specific activity towards the α-amylase from the insectTenebrio molitor as the native WMAI-1 isolated from wheat. This confirms that the native inhibitor is not glycosylated and contradicts claims that a putative glycosyl moiety was essential for inhibition. Thirteen mutants have been obtained at six different sites. Substitution of the highly conserved N-terminal S by the sequence ARIRAR increased the pre-incubation time required for maximum activity. A similar result was obtained by insertion of GPRLPW after position 4, while insertion of EPRAPW at the same position rendered the inhibitor inactive. The substitution D/EGPRL and insertions DGP or D, at position 58, produced complete inactivation. All other mutations had only minor effects on activity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00037140
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  • 68
    Digitale Medien
    Digitale Medien
    A Triticum aestivum cDNA clone encoding a low-molecular-weight heat shock protein (1991)
    Springer
    Plant molecular biology 17 (1991), S. 273-275 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Tahsp17.3 ; low-molecular-weight HSP ; Triticum aestivum L. ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00039504
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  • 69
    Digitale Medien
    Digitale Medien
    Unusual sequence of group 3 LEA (II) mRNA inducible by dehydration stress in wheat (1993)
    Springer
    Plant molecular biology 21 (1993), S. 907-912 
    Details
    ISSN: 1573-5028
    Schlagwort(e): abscisic acid ; dehydration ; LEA ; water stress ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A cDNA clone, pMA1949, detects two mRNA species in wheat seedling tissue that are late embryogenesis-abundant (LEA) and dehydration stress-inducible. Sequence analysis of the pMA1949 clone shows it to be a 991 bp partial cDNA encoding a polypeptide of 317 amino acids with homology to two group 3 LEA proteins, carrot (DC8) and a soybean protein encoded by pGmPM2 cDNA. Molecular analysis of the deduced protein reveals a 33 kDa acidic and extremely hydrophilic protein with potential amphiphilic α-helical regions. In addition, the protein contains eleven similar, contiguous repeats of 11 amino acids, which are separated by 118 amino acids from two additional and unique repeats of 36 residues each at the carboxyl end of the protein. Comparisons of sequences of reported group 3 LEA proteins revealed that there are two types, separable by sequence similarity of the 11 amino acid repeating motifs and by the presence or absence of a certain amino acid stretch at the carboxyl terminus. Based on resuls from these comparisons, we propose a second type of group 3 LEA proteins, called group 3 LEA (II).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00027121
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  • 70
    Digitale Medien
    Digitale Medien
    Wheat acetyl-CoA carboxylase (1993)
    Springer
    Plant molecular biology 22 (1993), S. 547-552 
    Details
    ISSN: 1573-5028
    Schlagwort(e): acetyl-CoA carboxylase ; chloroplast ; haloxyfop ; herbicide ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The acetyl-CoA carboxylase present in both wheat germ and total wheat leaf protein contains ca. 220 kDa subunits. It is the major biotin-dependent carboxylase present in wheat chloroplasts. Active acetyl-CoA carboxylase purified from wheat germ is a homodimer with an apparent molecular mass of ca. 500 kDa. The enzyme from wheat germ or from wheat chloroplasts is sensitive to the herbicide haloxyfop at micromolar levels. The incorporation of 14C-acetate into fatty acids in freshly cut wheat seedling leaves provides a convenient in vivo assay for both acetyl-CoA carboxylase and haloxyfop.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00015984
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  • 71
    Digitale Medien
    Digitale Medien
    Purification and characterization of (1→3, 1→4)-β-glucan endohydrolases from germinated wheat (Triticum aestivum) (1993)
    Springer
    Plant molecular biology 22 (1993), S. 847-859 
    Details
    ISSN: 1573-5028
    Schlagwort(e): amino acid sequence ; cDNA ; germination ; (1→3, 1→4)-β-glucanases ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A (1→3, 1→4)-β-glucan 4-glucanohydrolase [(1→3, 1→4)-β-glucanase, EC 3.2.1.73] was purified to homogeneity from extracts of germinated wheat grain. The enzyme, which was identified as an endohydrolase on the basis of oligosaccharide products released from a (1→3, 1→4)-β-glucan substrate, has an apparent pI of 8.2 and an apparent molecular mass of 30 kDa. Western blot analyses with specific monoclonal antibodies indicated that the enzyme is related to (1→3, 1→4)-β-glucanase isoenzyme EI from barley. The complete primary structure of the wheat (1→3, 1→4)-β-glucanase has been deduced from nucleotide sequence analysis of cDNAs isolated from a library prepared using poly(A)+ RNA from gibberellic acid-treated wheat aleurone layers. One cDNA, designated λLW2, is 1426 nucleotide pairs in length and encodes a 306 amino acid enzyme, together with a NH2-terminal signal peptide of 28 amino acid residues. The mature polypeptide encoded by this cDNA has a molecular mass of 32085 and a predicted pI of 8.1. The other cDNA, designated λLW1, carries a 109 nucleotide pair sequence at its 5′ end that is characteristic of plant introns and therefore appears to have been synthesized from an incompletely processed mRNA. Comparison of the coding and 3′-untranslated regions of the two cDNAs reveals 31 nucleotide substitutions, but none of these result in amino acid substitutions. Thus, the cDNAs encode enzymes with identical primary structures, but their corresponding mRNAs may have originated from homeologous chromosomes in the hexaploid wheat genome.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00027370
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  • 72
    Digitale Medien
    Digitale Medien
    Isolation and analysis of a cDNA clone encoding the small subunit of ADP-glucose pyrophosphorylase from wheat (1993)
    Springer
    Plant molecular biology 23 (1993), S. 23-33 
    Details
    ISSN: 1573-5028
    Schlagwort(e): wheat ; Triticum aestivum ; cDNA clone ; ADP-glucose pyrophosphorylase ; small-subunit ; starch
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A full-length cDNA clone from hexaploid bread wheat, encoding the small subunit of ADP-glucose pyrophosphorylase, has been isolated from an endosperm cDNA library. The cDNA insert has an open reading frame which encodes a protein of 473 amino acids (52.1 kDa). The presence of a chloroplast/amyloplast transit peptide of 22 amino acids is proposed. The deduced amino acid sequence exhibits a high degree of homology with the small subunit ADP-glucose pyrophosphorylase proteins from rice (with 90% of identical amino acids) and potato (with 86% of identical amino acids) and contains conserved sequence elements which are thought to represent the substrate binding and allosteric activator sites. The genes are organised as single-copy loci on chromosomes 7A, 7B and 7D in the wheat genome and are highly expressed during grain development. Homologous transcripts are expressed in leaves and roots.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00021416
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  • 73
    Digitale Medien
    Digitale Medien
    Molecular cloning and evolutionary analysis of the calcium-modulated contractile protein, centrin, in green algae and land plants (1993)
    Springer
    Plant molecular biology 23 (1993), S. 1243-1254 
    Details
    ISSN: 1573-5028
    Schlagwort(e): calcium-binding protein ; centrin ; EF hand ; evolution ; green algae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Centrin (= caltractin) is a ubiquitous, cytoskeletal protein which is a member of the EF-hand superfamily of calcium-binding proteins. A centrin-coding cDNA was isolated and characterized from the prasinophyte green alga Scherffelia dubia. Centrin PCR amplification primers were used to isolate partial, homologous cDNA sequences from the green algae Tetraselmis striata and Spermatozopsis similis. Annealing analyses suggested that centrin is a single-copy-coding region in T. striata and S. similis and other green algae studied. Centrin-coding regions from S. dubia, S. similis and T. striata encode four colinear EF-hand domains which putatively bind calcium. Phylogenetic analyses, including homologous sequences from Chlamydomonas reinhardtii and the land plant Atriplex nummularia, demonstrate that the domains of centrins are congruent and arose from the two-fold duplication of an ancestral EF hand with Domains 1+3 and Domains 2+4 clustering. The domains of centrins are also congruent with those of calmodulins demonstrating that, like calmodulin, centrin is an ancient protein which arose within the ancestor of all eukaryotes via gene duplication. Phylogenetic relationships inferred from centrin-coding region comparisons mirror results of small subunit ribosomal RNA sequence analyses suggesting that centrin-coding regions are useful evolutionary markers within the green algae.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00042357
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  • 74
    Digitale Medien
    Digitale Medien
    Cloning and sequencing of cDNAs encoding a pathogen-induced putative peroxidase of wheat (Triticum aestivum L.) (1991)
    Springer
    Plant molecular biology 16 (1991), S. 329-331 
    Details
    ISSN: 1573-5028
    Schlagwort(e): pathogen-induced ; peroxidase ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We report here the complete amino acid sequence of a pathogen-induced putative peroxidase from wheat (Triticum aestivum L.) as deduced from cDNA clones representing mRNA from leaves infected with the powdery mildew fungus Erysiphe graminis. The protein consists of 312 amino acids, of which the first 22 form a putative signal sequence, and has a calculated pI of 5.7. Sequence comparison revealed that the putative wheat peroxidase is most similar to the turnip (Brassica rapa) peroxidase, with which it shares 57% identical and 13% conserved amino acids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00020563
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  • 75
    Digitale Medien
    Digitale Medien
    Sequence and tissue-specific expression of a putative peroxidase gene from wheat (Triticum aestivum L.) (1991)
    Springer
    Plant molecular biology 16 (1991), S. 171-174 
    Details
    ISSN: 1573-5028
    Schlagwort(e): peroxidase gene ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have used a cDNA clone encoding a pathogen-induced putative wheat peroxidase to screen a genomic libary of wheat (Triticum aestivum L. cv. Cheyenne) and isolated one positive clone, lambda POX1. Sequence analysis revealed that this clone contains a gene encoding a putative peroxidase with a calculated pI of 8.1 which exhibits 58% and 83% sequence identity to the amino acid sequence of the turnip (Brassica rapa) peroxidase and a pathogen-induced putative wheat peroxidase, respectively. The two introns in the wheat gene are at the same positions as introns in the peroxidase genes of tomato and horseradish. Results of S1-mapping experiments suggest that this gene is neither pathogen-nor wound-induced in leaves but is constitutively expressed in roots.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00017928
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  • 76
    Digitale Medien
    Digitale Medien
    Structural features of the plastid ribosomal RNA operons of two red algae: Antithamnion sp. and Cyanidium caldarium (1991)
    Springer
    Plant molecular biology 16 (1991), S. 537-546 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Antithamnion sp. ; chloroplast ; Cyanidium caldarium Geitler ; evolution ; red algae ; rRNA operon ; rRNA spacer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The nucleotide sequences of the plastid 16S rDNA of the multicellular red alga Antithamnion sp. and the 16S rDNA/23S rDNA intergenic spacers of the plastid DNAs of the unicellular red alga Cyanidium caldarium and of Antithamnion sp. were determined. Sequence comparisons support the idea of a polyphyletic origin of the red algal and the higher-plant chloroplasts. Both spacer regions include the unsplit tRNAIle (GAU) and tRNAAla (UGC) genes and so the plastids of both algae form a homogeneous group with those of chromophytic algae and Cyanophora paradoxa characterized by ‘small-sized’ rDNA spacers in contrast to green algae and higher plants. Nevertheless, remarkable sequence differences within the rRNA and the tRNA genes give the plastids of Cyanidium caldarium a rather isolated position.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00023420
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  • 77
    Digitale Medien
    Digitale Medien
    Evolution of the Rubisco operon from prokaryotes to algae: Structure and analysis of the rbcS gene of the brown alga Pylaiella littoralis (1991)
    Springer
    Plant molecular biology 17 (1991), S. 853-863 
    Details
    ISSN: 1573-5028
    Schlagwort(e): algae ; endosymbiosis ; evolution ; plastidial DNA ; Rubisco operon
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The rbcS gene coding for the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) of the brown alga Pylaiella littoralis is located within the plastid genome and is transcribed as a single polycistronic mRNA with the gene for the large subunit of Rubisco, rbcL. The structure of the Rubisco operon from P. littoralis was determined. Molecular phylogenies for rbcS and rbcL with a wide range of prokaryotes and eukaryotes were constructed which are congruent with recent evidence for polyphyletic plastid origins. Both rbcL and rbcS of the β-purple bacterium Alcaligenes eutrophus clearly cluster with the rhodophyte and chromophyte proteins. The data suggest that the Rubisco operons of red algal and chromophytic plastids derive from β-purple eubacterial antecedents, rather than the cyanobacterial lineage of eubacteria from which other of their genes derive. This implies a lateral transfer of Rubisco genes from β-purple eubacterial ancestors to the cyanobacterial ancestor of rhodophyte and chromophyte plastids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00037066
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  • 78
    Digitale Medien
    Digitale Medien
    The atp1 and atp2 operons of the cyanobacterium Synechocystis sp. PCC 6803 (1991)
    Springer
    Plant molecular biology 17 (1991), S. 641-652 
    Details
    ISSN: 1573-5028
    Schlagwort(e): F-ATPase ; cyanobacteria ; operon ; evolution ; photosynthesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The two operons atp1 and atp2, encoding the subunits of the FOF1 ATP-synthase, have been cloned and sequenced from the cyanobacterium Synechocystis sp. PCC 6803. The organization of the different genes in the operons have been found to resemble that of the cyanobacteria Synechococcus sp. PCC 6301 and Anabaena sp. PCC 7120. The Synechocystis FOF1 ATP-synthase has nine subunits. A tenth open reading frame with unknown function was detected at the 5′ end of atp1, coding for a putative gene product similar to uncI in Escherichia coli. A promoter structure was inferred for the Synechocystis atp operons and compared to other known promoters of cyanobacteria. Even though the operon structure of atp1 and atp2 in Synechocystis resembles the corresponding operons of Synechococcus, the amino acid sequences of individual gene products show marked differences. Genetic distances between cyanobacterial genes and genes for ATP-synthase subunits from other species have been calculated and compiled into evolutionary trees.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00037050
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  • 79
    Digitale Medien
    Digitale Medien
    Sequence analysis of a cDNA encoding a Group 3 LEA mRNA inducible by ABA or dehydration stress in wheat (1991)
    Springer
    Plant molecular biology 16 (1991), S. 1073-1076 
    Details
    ISSN: 1573-5028
    Schlagwort(e): abscisic acid ; dehydration ; LEA ; water stress ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A cDNA clone (pMA2005) of a Group 3 LEA (late embryogenesis abundant) protein has been sequenced from wheat. The wheat cDNA clone codes for a protein with ten tandem repeats of an 11 amino acid sequence and has homology to other Group 3 LEAs reported in barley, carrot, cotton and rape (L. Dure et al., Plant Mol Biol 12: 475–486, 1989). The deduced amino acid sequence indicates that the wheat protein has a molecular weight of 23 000 and is a basic, hydrophilic protein. Northern analysis with the cDNA clone shows that dehydration of wheat shoot tissue results in increased transcript levels that correlate with increases in endogenous ABA.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00016078
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  • 80
    Digitale Medien
    Digitale Medien
    A novel proline-rich protein from wheat (1991)
    Springer
    Plant molecular biology 16 (1991), S. 663-670 
    Details
    ISSN: 1573-5028
    Schlagwort(e): gene expression ; proline-rich protein ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A cDNA (WPRP1) encoding a wheat proline-rich protein has been isolated and sequenced. The amino acid composition shows 45% proline, with high levels of methionine, lysine and glutamic acid. The derived 378 residue amino acid sequence has a highly repetitive structure which is unlike those of other proline-rich proteins. The WPRP1 cDNA clone was used to determine the copy number and chromosomal location of the WPRP1 gene by restriction fragment length polymorphism analysis of wheat inbred lines. Although WPRP1 is encoded by a single-copy gene it is also a representative of a larger family of related sequences. RNA gel blot analysis showed that expression of WPRP1 is highest in rapidly growing tissue which together with its amino acid composition suggests a structural role for the encoded protein.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00023430
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  • 81
    Digitale Medien
    Digitale Medien
    A wheat glutathione-S-transferase gene with transposon-like sequences in the promoter region (1991)
    Springer
    Plant molecular biology 16 (1991), S. 1089-1091 
    Details
    ISSN: 1573-5028
    Schlagwort(e): wheat ; glutathione-S-transferase ; transposon-like sequence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00016083
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  • 82
    Digitale Medien
    Digitale Medien
    Nucleotide sequence of a wheat (Triticum aestivum L.) cDNA clone encoding the waxy protein (1991)
    Springer
    Plant molecular biology 16 (1991), S. 1099-1101 
    Details
    ISSN: 1573-5028
    Schlagwort(e): wheat ; Triticum aestivum ; cDNA clone ; waxy protein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00016086
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  • 83
    Digitale Medien
    Digitale Medien
    Structure and sequence of a wheat phosphoribulokinase gene (1991)
    Springer
    Plant molecular biology 17 (1991), S. 167-168 
    Details
    ISSN: 1573-5028
    Schlagwort(e): chloroplast ; monocot gene ; phosphoribulokinase ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00036823
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  • 84
    Digitale Medien
    Digitale Medien
    Nucleotide sequence of a Triticum aestivum cDNA clone which is homologous to the 26 kDa chloroplast-localized heat shock protein gene of maize (1991)
    Springer
    Plant molecular biology 17 (1991), S. 255-258 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Tahsp26.6 ; chloroplast-localized HSP ; Triticum aestivum L. ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00039500
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  • 85
    Digitale Medien
    Digitale Medien
    The Rubisco activase (rca) gene is located downstream from rbcS in Anabaena sp. strain CA and is detected in other Anabaena/Nostoc strains (1993)
    Springer
    Plant molecular biology 21 (1993), S. 753-764 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Rubisco activase ; rca ; rbcLrbcS ; cyanobacteria ; expression ; evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract A gene encoding ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) activase (rca) was found downstream from the rbcLrbcS operon in the heterocystous cyanobacterium Anabaena sp. strain CA. Two unknown open reading frames were shown to be located between rbcS and rca in strain CA and all the genes, rbcLrbcS, ORF1, ORF2, and rca were in the same transcriptional orientation. The deduced amino acid sequence of the Anabaena Rubisco activase showed both similarities and differences to the plant enzyme with considerable differences at the carboxy and amino termini. Proposed ATP-binding sites were conserved in the cyanobacterial protein. Recombinant cyanobacterial Rubisco activase, however, reacted with antisera to spinach Rubisco activase. Hybridization studies, using the Anabaena sp. strain CA rca gene as a heterologous probe, detected homologous sequences in heterocystous Anabaena/Nostoc strains but not in unicellular or nonheterocystous filamentous cyanobacteria, suggestive of a close evolutionary relationship of chloroplasts and heterocystous cyanobacteria.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00027109
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  • 86
    Digitale Medien
    Digitale Medien
    Analysis of nuclear proteins interacting with a wheat α/β-gliadin seed storage protein gene (1993)
    Springer
    Plant molecular biology 22 (1993), S. 25-41 
    Details
    ISSN: 1573-5028
    Schlagwort(e): gliadin storage proteins ; wheat ; transcriptional regulation ; nuclear proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The promoter region (−524 to −46) of the wheat α/β-gliadin seed storage protein gene was analyzed for interactions with nuclear proteins from developing wheat seeds. Six complexes were detected within the first 165 bp upstream of the transcriptional start site. One of the proteins was a non-sequence specific AT-binding protein. The remaining five proteins bound in a sequence specific manner. One (CABP) mapped to a conserved CA-rich element at −134 to −112 while another (PalBP) mapped to an adjacent, palindromic sequence at −112 to −106. Three proteins (CTBPs 1–3) formed complexes at two, independent homologous sites. The activities of four of the binding proteins, CTBPs 1–3 and CABP, exhibited similar patterns of expression during seed development: they first appeared at early to mid stages, reached a maximum at mid stage and subsequently decreased, paralleling the pattern of gliadin mRNA accumulation. The non-specific AT-binding protein was detected at relatively high levels only at mid development. PalBP activity, on the other hand, first appeared at mid stage and was present at a constant level throughout later stages of development. The results suggest that the binding proteins may regulate gliadin expression in an antagonistic manner.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00038993
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  • 87
    Digitale Medien
    Digitale Medien
    A light- and developmentally-regulated DNA-binding interaction is common to the upstream sequences of the wheat Calvin cycle bisphosphatase genes (1993)
    Springer
    Plant molecular biology 22 (1993), S. 507-516 
    Details
    ISSN: 1573-5028
    Schlagwort(e): Calvin cycle genes ; DNA-binding proteins ; wheat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have characterised a DNA-binding interaction common to the upstream sequences of the wheat fructose-1,6-bisphosphatase (FBPase) and sedoheptulose-1,7-bisphosphatase (SBPase) genes. The recognition site for this sequence-specific binding activity, designated wheat FBPase factor (WF-1), is located within 125 bp of the transcription start site of each gene. Within these regions there are no sequence motifs similar to those shown to be important for light-regulated expression in other species. The binding activity was not detected in wheat root nuclear extracts, or in pea leaf extracts. There was a higher level of binding activity in light-grown than in dark-grown wheat leaves. The level was also found to decline when light-grown plants were given an extended dark treatment, but could be reinduced by light. Utilising the gradient of developmental maturity which exists within the wheat leaf it was found that WF-1 activity increases during leaf development.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00015979
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  • 88
    Digitale Medien
    Digitale Medien
    Peptidergic motoneurons in the buccal ganglia of Aplysia californica Immunocytochemical, morphological, and physiological characterizations (1991)
    Springer
    Journal of comparative physiology 168 (1991), S. 323-336 
    Details
    ISSN: 1432-1351
    Schlagwort(e): Aplysia ; Motoneurons ; Immunocytochemistry ; Small cardioactive peptides ; Facilitation ; Depression ; Buccal ; Feeding
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary We used physiological recordings, intracellular dye injections and immunocytochemistry to further identify and characterize neurons in the buccal ganglia of Aplysia calif ornica expressing Small Cardioactive Peptide-like immunoreactivity (SCP-LI). Neurons were identified based upon soma size and position, input from premotor cells B4 and B5, axonal projections, muscle innervation patterns, and neuromuscular synaptic properties. SCP-LI was observed in several large ventral neurons including B6, B7, B9, B10, and B11, groups of s1 and s2 cluster cells, at least one cell located at a branch point of buccal nerve n2, and the previously characterized neurons B1, B2 and B15. B6, B7, B9, B10 and B11 are motoneurons to intrinsic muscles of the buccal mass, each displaying a unique innervation pattern and neuromuscular plasticity. Combined, these motoneurons innervate all major intrinsic buccal muscles (I1/I3, I2, I4, I5, I6). Correspondingly, SCP-LI processes were observed on all of these muscles. Innervation of multiple nonhomologous buccal muscles by individual motoneurons having extremely plastic neuromuscular synapses, represents a unique form of neuromuscular organization which is prevalent in this system. Our results show numerous SCPergic buccal motoneurons with widespread ganglionic processes and buccal muscle innervation, and support extensive use of SCPs in the control of feeding musculature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00198352
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  • 89
    Digitale Medien
    Digitale Medien
    Development of the diffuse endocrine system in the chicken proventriculus (1993)
    Springer
    Cell & tissue research 271 (1993), S. 107-113 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Proventriculus ; Endocrine ontogenesis ; Ultrastructure ; Regulatory peptides ; Immunocytochemistry ; Silver impregnations ; Chicken
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The development of endocrine cells in the chicken proventriculus has been investigated using light-and electron-microscopy in conjunction with silver and immunocytochemical techniques. The first morphologically detectable endocrine cells were found in 5-day-old embryos by electron microscopy. From the 9th to the 13th day, endocrine cells in contact with the lumen of the organ could be detected both by electron and light (silver impregnation) microscopy. The number of open-type endocrine cells progressively decreased and the number of closed-type increased after this stage. Until the 16th day, endocrine cells were located exclusively in the luminal epithelium, but afterwards they appeared in progressively greater numbers in the compound glands. After hatching, long cytoplasmic processes could be seen in the endocrine cells. Immunoreactivities to regulatory substances appeared in the following order: serotonin (day-14), avian pancreatic polypeptide, glucagon and somatostatin (day-16), bombesin and neurotensin (day-18), and finally, met-enkephalin (day-21).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00297548
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  • 90
    Digitale Medien
    Digitale Medien
    Epidermal calcium-binding protein: a marker of early differentiation of basal layer keratinocytes of rats (1993)
    Springer
    Cell & tissue research 272 (1993), S. 161-168 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Keratinocyte subpopulations ; Epidermal calcium-binding protein ; Low gravity sedimentation ; Immunoblotting ; Immunocytochemistry ; Flow cytometry ; Rats (Wistar)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Epidermal calcium-binding protein (ECaBP) is present in the cells of the basal layer of the epidermis and other stratified epithelia. Since the basal layer compartment contains at least two types of cells: slow-cycling, poorly-differentiated, and actively proliferating, more differentiated cells, it was of interest to determine whether they both contained ECaBP. Basal and nearly suprabasal layer keratinocytes from newborn rat epidermis were fractionated into three fractions on the basis of cell size, using low-gravity sedimentation. The cell differentiation in each subgroup was estimated by cell size, morphology, cell cycle stage, RNA/DNA content, and the presence of specific keratins. The presence of ECaBP in these fractions was detected by immunocytochemistry and immunoblotting. Double staining with ECaBP antibodies and propidium iodide followed by flow cytometry was used to correlate ECaBP production and the stage of cell cycle. The relative cell size, measured by the light scattering was used to study the relationship between cell size and ECaBP production. The results show that small keratinocytes with low DNA and RNA content (G0 cells) do not express ECaBP. ECaBP was found only in intermediate size basal keratinocytes with higher DNA and RNA contents, corresponding to actively proliferating S phase cells. Large keratinocytes, which express suprabasal keratin and have low DNA and high RNA content, cease to express ECaBP. ECaBP may, therefore, be a useful marker for assessing the movement of cells from poorly differentiated reserve compartment towards proliferation and further differentiation in both physiological and pathological situations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00323582
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  • 91
    Digitale Medien
    Digitale Medien
    Cellular localization of somatolactin in the pars intermedia of some teleost fishes (1991)
    Springer
    Cell & tissue research 263 (1991), S. 207-215 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Somatolactin (SL) ; Pituitary gland, pars intermedia ; PAS-positive cells ; Immunocytochemistry ; Gadus morhua, Oncorhynchus mykiss, Poecillia latipinna (Teleostei)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary We report here on the cellular localization in the fish pituitary of somatolactin (SL), a putative new pituitary hormone related to growth hormone and prolactin, which has been recently identified in the piscine pituitary gland. Immunocytochemical staining, using anti-cod SL serum, revealed that in the cod pituitary gland, SL is produced by cells in the intermediate lobe, bordering the neural tissue. These cells, staining weakly with periodic-acid-Schiff (PAS), are distinct from the melanocyte stimulating hormone (MSH) cells which, as in all teleosts, are PAS-negative. SL-immunoreactivity was observed in the same location in all other teleost species examined: flounder, rainbow trout, killifish, molly, catfish and eel. In most fish the SL-immunoreactive cells are either strongly or weakly PAS-positive but in rainbow trout are chromophobic, indicating that the SL protein can probably exist in glycosylated and non-glycosylated forms. Thus, in demonstrating the cellular localization of SL, this study provides the first identification of the enigmatic, second cell-type of the fish pars intermedia.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318762
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  • 92
    Digitale Medien
    Digitale Medien
    Neurofilaments in rat and cat spinal cord; a comparative immunocytochemical study of phosphorylated and non-phosphorylated subunits (1993)
    Springer
    Cell & tissue research 272 (1993), S. 249-256 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Spinal cord ; Motoneurones ; Dorsal horn ; Neurofilament ; Phosphorylation ; Immunocytochemistry ; Rat ; Cat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Neurofilament immunoreactivity was examined in spinal cords of rats and cats with antibodies to all three subunits (68 kD, 155 kD and 200 kD) and to different phosphorylation states of 200 kD. NFHP-, an antibody against non-phosphorylated 200 kD, labelled all rat neuronal perikarya but failed to labet cat neurofilaments. In both species, the perikarya and processes of motoneurones were immunoreactive for all three subunits but most dorsal horn neuronal perikarya were not immunoreactive for 68 kD and 155 kD. Motoneuronal perikarya and proximal processes showed filamentous labelling for 68 kD but not for 155 kD in the rat, while in neither species did these show labelling with RT97, an antibody against a highly phosphorylated form of 200 kD; immunoreactivity for 200 kD was present in both filamentous (probably partially phosphorylated) and non-filamentous (non-phosphorylated) forms, but in dorsal horn neurones only the latter was present. Interpretations consistent with this data are: in rat and possibly also cat, motoneuronal neurofilaments consist of a 68 kD backbone with partially phosphorylated 200 kD sidearms, with both 155 kD and 200 kD (non-phosphorylated) subunits in a non-filamentous form; this neurofilament becomes more highly phosphorylated along the proximal processes. The dorsal horn neurones probably contain 200 kD in a non-filamentous form but may lack the other subunits.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00302730
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  • 93
    Digitale Medien
    Digitale Medien
    Qualitative and quantitative comparison of the distribution of phosphorylated and non-phosphorylated neurofilament epitopes within central and peripheral axons of adult hamster (Mesocricetus auratus) (1991)
    Springer
    Cell & tissue research 263 (1991), S. 265-270 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Neurofilaments ; Phosphorylation ; Axon ; Immunocytochemistry ; Golden syrian hamster, Mesocricetus auratus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The distribution of phosphorylated and nonphosphorylated neurofilament epitopes was determined immunocytochemically in adjacent 2 μm-thick sections of sciatic nerve, ventral root and spinal cord. Staining was scored as either intense, moderate or absent and the proportion of labeled axons was calculated for each category. Nearly all sciatic nerve and ventral root axons were immunoreactive with both antibodies against phosphorylated and non-phosphorylated neurofilaments and there were no significant differences in the number of intensely- or moderately-labeled axons. Within the spinal cord however, while the majority of large caliber axons was stained with both antibodies, there was a significant number of small caliber axons which stained only with antibodies against phosphorylated neurofilaments. These results show that phosphorylated and nonphosphorylated neurofilaments are extensively codistributed in CNS and PNS axons, and that in the CNS, staining intensity for non-phosphorylated epitopes is less in the smaller axons.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318768
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  • 94
    Digitale Medien
    Digitale Medien
    The serotoninergic system in the brain of the Japanese quail (1991)
    Springer
    Cell & tissue research 263 (1991), S. 271-284 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Serotonin ; Immunocytochemistry ; Avian brain ; Hypothalamus ; Japanese quail, Coturnix coturnix japonica (Aves)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The presence and topographical localization of the serotoninergic system in the brain of the Japanese quail (Coturnix coturnix japonica) have been studied by means of peroxidase-anti-peroxidase immunocytochemistry. The perimeter, diameter, area, and shape factor of immunoreactive cells have been recorded and analyzed morphometrically for intra- and interspecies comparison. The data reported here confirm and extend results previously obtained in the brain of other avian species. Serotonin-immunoreactive neurons of the quail are mainly located in the hypothalamic paraventricular organ and adjacent areas, and in the brainstem where they form three separate groups. The first of these groups consists of small-sized neurons located in the ventro-rostral mesencephalon. The second group is composed of medium-sized neurons located in the dorsal mesencephalo-pontine region. The third group is also formed by medium-sized neurons, and is located ventrally in the ponto-medullary region. In the quail brain, serotoninergic neurons are not restricted to nuclei located in the vicinity of the midsagittal plane, but show some lateralization, especially in the brainstem. The organization of the different groups of immunoreactive neurons based on this topographical distribution and morphometric analysis has been compared with descriptions of the serotoninergic system in other birds. Serotonin-immunoreactive nerve fibers are widely distributed throughout the brain, but appear to be particularly abundant in regions involved in the control of reproductive activities, such as the septal region, the medial preoptic nucleus, the nucleus intercollicularis, and the external zone of the median eminence. The data reported here have allowed the drawing of a map of serotoninimmunoreactive structure.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318769
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  • 95
    Digitale Medien
    Digitale Medien
    Immunocytochemical mapping of neuronal pathways from brain to corpora cardiaca/corpora allata in the cockroach Diploptera punctata with antisera against Met-enkephalin-Arg6-Gly7-Leu8 (1991)
    Springer
    Cell & tissue research 263 (1991), S. 285-291 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Met-enkephalin-Arg6-Gly7-Leu8 ; Immunocytochemistry ; Neuropeptides ; Allatostatins ; Neurosecretory cells ; Corpus cardiacum/corpus allatum complex ; Diploptera punctata, Calliphora vomitoria (Insecta)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary Neuronal circuits in the brain and retrocerebral complex of the cockroach Diploptera punctata have been mapped immunocytochemically with antisera directed against the extended enkephalin, Met-enkephalin-Arg6-Gly7-Leu8 (Met-8). The pathways link median and lateral neurosecretory cells with the corpus cardiacum/corpus allatum complex. In females, nerve fibres penetrate the corpora allata and varicosities or terminals, immunoreactive to Met-8, surround the glandular cells. Males differ in having almost no Met-8 immunoreactivity in the corpora allata. The corpora cardiaca of both males and females are richly supplied with Met-8 immunoreactive material, in particular in the ‘cap’ regions immediately adjacent to the corpora allata. A similarity in the amino-acid sequences of Met-8 and the C-terminus of the recently characterised allatostatins of D. punctata suggests that the pathways identified with the Met-8 antisera may be the same as those by which the allatostatins are transported from the brain to the corpus allatum. In comparative studies on the blowfly Calliphora vomitoria, similar neuronal pathways have been identified except that no sexual dimophism with respect to amounts of immunoreactive material within the corpus allatum has been observed. These results suggest a possible homology in the neuropeptide regulation of the gland.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318770
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  • 96
    Digitale Medien
    Digitale Medien
    Immunocytological localization of 1,25-dihydroxyvitamin D3-like molecules and their receptors in a calcium-transporting epithelium of a crustacean (1991)
    Springer
    Cell & tissue research 263 (1991), S. 345-351 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Vitamin D-1,25(OH)2D3-like immunoreactivity ; 1,25(OH)2D3 receptor-like immunoreactivity ; Immunocytochemistry ; Calcium ions ; Orchestia cavimana (Crustacea)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary For the first time, immunoreactivity to 1,25(OH)2D3-like molecules and their receptors has been investigated in a calcium transporting epithelium of a crustacean, Orchestia, using vertebrate antisera on ultrathin cryosections of posterior caeca previously fixed in glutaraldehyde, then postfixed in osmium tetroxide. Both immunoreactivities were located mainly in the nuclei of epithelial cells. Quantitative differences in 1,25(OH)2D3-like immunoreactivity were noticed from one stage of the molt cycle to another. These results, together with other data, contribute to evidence that immunoreactive 1,25(OH)2D3-like molecules may be involved in the regulatory processes of calcium metabolism in this terrestrial crustacean and suggest an involvement of these substances in the regulation of calcium movements in the posterior caeca.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00318776
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  • 97
    Digitale Medien
    Digitale Medien
    Co-existence of gonadotrophins (FSH, LH) and thyrotrophin (TSH) in single anterior pituitary cells of the musk shrew, Suncus murinus (1993)
    Springer
    Cell & tissue research 272 (1993), S. 315-320 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Pituitary gland, pars anterior (distalis) ; Gonadotrophic cells, gonadotropes ; Thyrotropes ; Immunocytochemistry ; Suncus murinus (Insectivora)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract According to recent immunocytochemical studies of anterior pituitary cells, it is obvious that the “one cell-one hormone” theory must be modified. Many pituitary morphologists have demonstrated that there are some cells that contain two hormones. In this study, we demonstrate by means of immuno-electronmicroscopy the co-existence of gonadotrophins (FSH and LH) and thyrotrophin (TSH) in the same anterior pituitary cells of the musk shrew. These cells were remarkably altered in their ultrastructural features by either gonadectomy or thyroidectomy. Double labeling for gonadotrophins and thyrotrophin was present not only in the same cells but also in the same secretory granules. Our ability to demonstrate co-existence of gonadotrophins and thyrotrophin in the same cell may be due to our selection of fixative and embedding media for electron-microscopic immunocytochemistry. Our conclusion that gonadotrophins and thyrotrophin are produced in a single cell type of the anterior pituitary gland in the musk shrew, i.e., thyrogonadotrophs, suggests the need to consider a modification of the classic scheme for classification of anterior pituitary cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00302736
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    Enkephalin-like immunoreactive neurons in the central nervous system of gastropods (Helix pomatia, Lymnaea stagnalis, Aplysia californica): a comparative immunocytochemical study (1993)
    Springer
    Cell & tissue research 272 (1993), S. 329-341 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Opioid peptides ; Met-enkephalin ; Leuenkephalin ; Immunocytochemistry ; Nervous system, central ; Helix pomatia (Mollusca) ; Lymnaea stagnalis (Mollusca) ; Aplysia californica (Mollusca)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The distribution and morphology of met-enkephalin-like immunoreactive (MetLI) and leu-enkephalin-like immunoreactive (LeuLI) neurons were investigated in the central nervous system of three gastropod species, Helix pomatia, Lymnaea stagnalis and Aplysia californica. Differences between the three species were observed in (1) the characteristics of immunostaining with antibodies to met-enkephalin and leu-enkephalin antibodies; (2) the number of immunostained neurons; (3) the projection areas of imunostained elements; (4) the specificity of immunostaining. Differences in the appearance of MetLI and LeuLI neurons were apparent: in Aplysia, both MetLI and LeuLI neurons could be observed, whereas in Lymnaea LeuLI was only found in fibers; only MetLI neurons occurred in Helix. According to an absorbtion control specificity test, a part of the LeuLI seen in the neuropil of Aplysia ganglia did not represent authentic leu-enkephalin. In Helix pomatia, significantly more MetLI neurons were present than in the CNS of Lymnaea and Aplysia; the majority of these neurons were concentrated in the cerebral ganglia and were small-size (12–25 μm) interneurons. In addition to central and peripheral projections observed in the three species, the connective tissue sheath around the ganglia and peripheral nerves contained MetLI varicose axons only in Helix, where a possible neurohormonal role could be attributed to these substance. The mapping and detailed chemical-neuroanatomical description of enkephalin-immunoreactive elements may furnish a chemical-neuroanatomical background to facilitate further neurophysiologic and pharmacologic analysis of enkephalinergic mechanisms in the gastropod CNS.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00302738
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    Immunocytochemical studies of chicken somatotrophs and somatotroph granules before and after hatching (1993)
    Springer
    Cell & tissue research 272 (1993), S. 369-374 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Somatotrophs ; Somatotroph granules ; Growth hormone ; Immunocytochemistry ; Developments ontogenic ; Domestic fowl
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Immunocytochemical methods were used to gain information about the embryonic development of chicken somatotrophs before and after hatching. To localize growth hormone, anterior pituitary sections were incubated with growth-hormone antibody, and then an indirect peroxidase method was used for light microscopy and an immunogold method for electron microscopy. The earliest evidence of embryonic somatotrophs was seen at 12 days. At this stage somatotrophs were sparse (0.2% of parenchymal cells) and their granules were pleomorphic with elongated ovoid and lozenge shapes predominating. Few of the immunogold-labeled somatotroph granules of the embryo were spherical until 15 days after fertilization. At 18 days, most of the granules were spherical (their shape in the adult chicken). During the six days between the 15-day-old embryo and the 1-day-old chick, the number of gold particles per granule section approximately doubled suggesting an increase in growth hormone content of the granules. This rise was the result of increases in the size of the granule sections and in the concentration of gold particles in the sections. During the embryonic period of 12–20 days, somatotrophs were not more than 3.6% of the anterior pituitary cell population. During the following two days, between the 20-day-old embryo and the 1-day-old chick, the percentage of somatotrophs in the pituitary parenchymal cell population rose rapidly from 3.6% to 20.7% and then increased slowly to 24.6% during the period of 1–5 days after hatching. Both the sharp percentage rise in somatotrophs (20-day-old embryo to 1-day-old chick) and the rise in growth hormone content of the granules (15-day-old embryo to 1-day-old chick) suggested by gold-particle counts occur close to the time of hatching. These morphological changes may reflect an increased synthesis of growth hormone that is responsible for the rise in plasma growth-hormone concentration that begins about the same time and is especially abrupt two days later (1–3 days after hatching).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00302741
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    Digitale Medien
    Digitale Medien
    Different epithelia in the distal human male urethra (1991)
    Springer
    Cell & tissue research 264 (1991), S. 23-32 
    Details
    ISSN: 1432-0878
    Schlagwort(e): Male urethra ; Urethral epithelium ; Immunocytochemistry ; Ultrastructure ; Man
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The distal segment of the human male urethra, in particular the fossa navicularis, was studied with light- and electron microscopy as well as by means of histochemical and immunocytochemical methods. The fossa navicularis of the urethra contains a circumscribed zone of extremely thick, non-keratinized stratified squamous epithelium composed of cells containing a large amount of glycogen. These cells lack acid phosphatase activity and lysozyme-like immunoreactivity, both of which can be demonstrated to varying extents in the other zones of the distal male urethra. These glycogen-rich cells are considered to be the substrate for an endogenous flora of lactobacteria, whereas the acid-phosphatase activity and the lysozyme-like immunoreactivity indicate the presence of macrophages and the secretion of bactericidal agents at the epithelial surface. These observations suggest that the different zones with heterogeneous properties in the distal male urethra probably represent a defense system against the invasion of pathogenic microorganisms. Moreover, the glycogen-rich zone, which resembles the glycogen-rich epithelium of the vagina, is estrogen-dependent. This is demonstrated in cases of sex reversal in which after long-lasting estrogen treatment the glycogen-rich zone becomes extremely extended by displacement of the neighbouring epithelium.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00305719
    Standort Signatur Erwartet Verfügbarkeit
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