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  • Articles  (1,372)
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  • Molecular Sequence Data  (1,179)
  • Engineering
  • thin films
  • 1990-1994  (1,372)
  • 1945-1949
  • Physics  (1,197)
  • Electrical Engineering, Measurement and Control Technology  (185)
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  • Articles  (1,372)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of superconductivity 7 (1994), S. 127-130 
    ISSN: 1572-9605
    Keywords: Superconductivity ; thin films ; photoconduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The photoinduced enhancement of superconductivity in RBa2Cu3O x (R=rare earth or yttrium) and Pr y R1−y Ba2Cu3O x was explored through temperature-dependent resistivity, Hall coefficient and mobility, and x-ray diffraction measurements. The increases inT c are enhanced near the metal-insulator transition, although photoinduced changes always exist in oxygendeficient samples. Several explanations, including intergrain Josephson coupling, photoassisted oxygen ordering, and the trapping of photogenerated electrons in oxygen vacancies, are discussed.
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  • 2
    ISSN: 1573-2746
    Keywords: thin films ; high temperature superconductor ; grain boundaries ; microstructure ; transport properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The microstructure and transport properties of various 90° grain boundaries in (103) oriented YBa2Cu3O7(YBCO) thin films grown epitaxially in situ by 90° off-axis sputtering are compared. The (103) films grown on (101) LaAlO3 and (101) SrTiO3 substrates have specific sets of 90° grain boundaries in both principal in-plane directions: 90° [010] twist boundaries along the [101] direction, and 90° [010] symmetrical tilt boundaries and 90° [010] basal-plane-faced tilt boundaries along the (301) direction. No weak-link behavior is observed across some of these boundaries by transport critical current density and normalized magnetic field dependence of J c measurements along both those in-plane directions. High-resolution transmission electron microscopy reveals variations in the structure and microfaceting of the 90° boundaries, which may contribute to the absence of weak-link behavior. These results have important implications for understanding the behavior of step-edge Josephson junctions.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Interface science 1 (1994), S. 371-384 
    ISSN: 1573-2746
    Keywords: interfaces ; multilayers ; thin films ; epitaxy ; transmission electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The interfacial microstructures in CaTiO3/YBa2Cu3O7-x /SrTiO3/LaAlO3/CaRuO3 multilayers grown on (001) LaAlO3 substrates has been characterized using transmission electron microscopy in combination with scanning electron microscopy. The morphology of films grown on both flat surfaces and on stepped surfaces patterned by ion beam milling were interpreted in terms of effects that influence epitaxial orientation relationships, nucleation of Y2O3 particles, and pinhole formation. The general conclusions are that a-axis oriented YBa2Cu3O7-x particles should be avoided in multilayer structures. The particles give rise to cracking and pinhole formation. Local surface roughness, which may be due to ion beam milling or to the growth mechanism of YBCO, induces Y2O3 particle nucleation and pinhole formation. Very steep surface slopes cause the formation of a-axis YBa2CU3O7-x particles. A critical size effect of the Y2O3 particles is suggested.
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  • 4
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    Springer
    Journal of superconductivity 7 (1994), S. 231-233 
    ISSN: 1572-9605
    Keywords: YBa2Cu3O7 ; thin films ; large-area deposition ; semiconductor substrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Our technique of reactive thermal co-evaporation has been extended to fabricate large films (up to 4 in.) of YBa2Cu3O7 with high quality. A rotating substrate holder is used to separate the deposition and oxidation processes. This allows free access of the metal vapors. As large substrate wafers we use Al2O3, Si, and GaAs with buffer layers of CeO2, YSZ, and MgO, respectively. On all substrates, the uniformity of thickness and composition was better than 2%. Inductively measuredT c andj c (77 K) were 87.5±0.2 K and 〉1×106 A/cm2, respectively, across the full wafer area. This holds also for GaAs substrates due to a new procedure of capping by Si3N4.
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  • 5
    ISSN: 1572-9605
    Keywords: Photoconductivity ; high-T c superconductors ; thin films ; spectral dependence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Temperature and spectral dependences of photoinduced changes of resistance were measured in YBa2Cu3O x thin films with oxygen content ranging as 6.35 〈x 〈 6.75. The absolute value of efficiency of initiation of photoinduced changes decreases with increase in oxygen content, but the position of peaks in the spectral dependence does not change with a change ofx. Temperature dependences of efficiency have an anomaly atT∽220 K, which is present in all the samples studied, and correlates with anomalies observed by other experimental techniques. Qualitatively similar temperature and spectral dependences of efficiency for the samples in both the insulating and metallic phases may be considered as an indication that the persistent photoconductivity effect in YBCO on both sides of the metal-insulator transition has a common origin.
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  • 6
    Electronic Resource
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    Springer
    Journal of superconductivity 7 (1994), S. 849-851 
    ISSN: 1572-9605
    Keywords: High-temperature superconductors ; thin films ; critical current ; flux creep
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Flux creep characteristics ofc-axis-oriented Bi2Sr2CaCu2O x thin films grown by the method of electron beam evaporation of stoichiometric target and subsequent annealing have been investigated in the absence of external magnetic field. A decrease of the pinning potential with decreasing temperature is obtained fromI–V curves. This result is explained by the presence of the spatially nonlinear pinning potential.
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  • 7
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    Springer
    Journal of superconductivity 7 (1994), S. 767-771 
    ISSN: 1572-9605
    Keywords: Tl cuprates ; thin films ; ex-situ thin film processing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Anex situ process has been developed to produce thin superconducting Tl2Ba2CaCu2O8 films. The properties of films grown on different substrates using different annealing regimes were studied. Critical temperatures of 103–107 K were measured on films prepared in a broad range of annealing temperatures on SrTiO3, LaAlO3, and Y-ZrO2 substrates. A critical current density,J c, of 2×106 A/cm2 at 77 K was measured on LaAlO3. Film morphology was studied by SEM, AFM, and STM.
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  • 8
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. i 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 9
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 75-75 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 10
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 127-139 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: In this paper the traditional square mesh 2D-TLM algorithm is generalized for rectangular meshes of arbitrary aspect ratio. It is shown that the anisotropic rectangular TLM network can be conceived in such a way that the propagation vector remains independent of the direction of propagation in the infinitesimal approximation. A full dispersion analysis of the rectangular mesh in then performed for the general case, and results are compared to that of the traditional square mesh.
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  • 11
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 155-166 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The radiation field patterns of rectangular waveguides and horns of finite dimensions are obtained numerically. The electric field integral equation is formulated to relate their radiation patterns to the surface current distribution. These currents are determined numerically by reducing the integral equation to a matrix equation, using the moment method. The computed currents are then used to calculate the radiation patterns and cross-polar fields of the finite wavegiudes and horns. The method is numerically efficient and can be applied to the computation and optimization of the antenna feed configurations.
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  • 12
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 167-177 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Ray-besed methods have been previously developed for accurately predicting the electromagnetic scattering from cavity interiors that allowed for realistic modelling of complex cavities such as jet engine inlets. An analytic geometric model is developed for bifurcated cavities based on connecting sections of generalized super-ellipse functions. The electromagnetic scattering from such cavities using the ‘shooting and bouncing rays’ (SBR) method is discussed.
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  • 13
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 209-221 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A theoretical analysis has been developed to study the crosstalk in crossed bundles of parallel lines. The model is based on the theory of the coupled transmission lines and the resulting system of differential equations has been solved by means of the finite difference, time-domain (FDTD) method. The frequency response of the network has been achieved by the discrete fourier transform (DFT) algorithm; measurements, performed with a vectorial network analyser, show a good agreement with numerical simulation.
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  • 14
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 35-41 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The eigenmodes in electromagnetic cavities, loaded with arbitrarily shaped dielectric materials, are computed by the edge element method. The computation shows that the well known ‘spurious modes’ no longer appear. Formulae are given and verified so that the number of zero eigenvalues, which come from ∇ × H = 0, may be accurately predicted. Formulae for the order and density of the global matrices are given for a rectangular cavity regularly divided into bricks and tetrahedra, allowing an associated comparison between the contrasting edge and nodal element formulations. Comparison of the computed results with available theoretical and previously published data show the edge element approach to be a robust, accurate and effective method.
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  • 15
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 253-265 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A numerical frequence-domain modelling of two-terminal, non-linear microwave circuits is presented. It basically relies on a process allowing the solution of the frequency-domain curcuit harmonic balance equations while accounting for the semiconductor device by means of an accurate numerical macroscopic physical model. In its present state of development, the model allows the study of a single two-terminal device circuit operating in harmonic mode. Its capabilites are illustrated by means of the results of a study devoted to the optimization of the load curcuit configuration of a millimetre-wave avalanche diode frequency multiplier. The influence of the output load impedance level on the circuit output RF performance has been investigated for different input power levels in direct frequency multiplication mode and in the presence of additional circuit tunings at low harmonic rank idler frequencies.
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  • 16
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994) 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 17
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 309-319 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes a rigorous and systematic procedure to derive a non-linear distributed FET model that an easily be implemented in CAD routines of simulators based on harmonic balance techniques. The new model is derived from a knowldge of the conventional linear lumped equivalent circuit, from non-linear current sources extracted with pulsed measurements, and from the physical dimensions of the FET.For fundamental and haromonic requencies, the FET is modelled by N identical cells. Each cell is made up of a non-linear two-port section inserted between two linear four-port sections that simulate the coupling and the distributed effects along the electrodes of the FET in the width direction only. This non-linear distributed scaling approach to FET modelling has been applied to the analysis of a submicrometre-gate GaAs FET at Millimetre-wave frequencies, and the results were compared to the non-linear lumped element approach. This approach can be applied to other transistors used in non-linear regions at microwave and millimetre-wave frequencies.
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  • 18
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 375-375 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 19
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. ii 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 20
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 399-405 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Symbolic computational systems introduce some unique features in computational engineering. There have been several papers published on the solution of differential equations under given boundary conditions by symbolic systems. The finite element formalism has received prime attention in the course of development of symbolic computation in engineering. The main idea has been to develop a symbolic FEM package to reduce the burden of manual algebra, eliminate errors introduced by numerical quadrature, and improve the efficiency of element generation.This work discusses a symbolic solution to electromagnetic linear antenna problems. The solution is a method of moments that transforms Pocklington's integral equation to a matrix equation. The symbolic system is used to produce (1) analytical integration, (2) the parametric expression for the input impedance and (3) computational code for forward and reverse problem of the input impedance.
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  • 21
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 419-432 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper presents a new finite element formulation in the Laplace domain for both diffusion and wave equations with applications in the field of electrical engineering. With the aid of congruence transformation of matrices, the finite element equations in the Laplace domain are solved and time-domain results can be obtained through the inverse Laplace transform. In a test problem, good agreement between the numerical results derived with the present method and the analytical solutions has been found. For applications in which only Dirichlet and Neumann boundary conditions are involved, this new finite element approach can be applied and provide both frequency-domain and time-domain results in one run without any timestepping scheme. The limitations of using the congruence transformation in solving propagation problems are also addressed in this paper.
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  • 22
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 433-452 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A hybrid method obtained as a combination of the coupled-mode method (CMM) and the mode-matching method (MMM) is developed and applied in the analysis of multiple dielectric and magnetic discontinuities in rectangular waveguides. As both are moment methods, some kind of truncation has to be carried out in the computer implementation. It is shown that selection of a different number of modes in the two methods is not necessary, unless low-permittivity meida inside the waveguide are considered. As a consequence, the procedure for slecting the number of basis functions is only done in one of the methods. Numerical examples are presented showing the behaviour of the method and the proofs of convergence. Examples are included illustrating the power of this hybrid technique, especially in relation to non-reciprocal structures containing magnetized ferrites.
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  • 23
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994) 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 24
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 15-24 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper describes the application of the boundary element method to solving two-dimensional steady slow viscous flow problems (creeping flow) in thermal silicon oxidation. The proposed method used the velocity-pressure formulation. The use of the incompressibility condition as a boundary condition and the application of the second Green's identity to transform the domain integral into a boundary integral result in a system of three boundary integral equations for velocity components and pressure. Solution of this system to be an ill-posed problem because of the presence of boundary conditions of the first kind. Two methods of regularization are employed. The numerical results for trench oxidation process are presented.
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  • 25
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994) 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 26
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 43-67 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The particle-in-cell method is coupled with boundary-fitted co-ordinates in order to model the stationary Maxwell-Lorentz problem in technical devices. New numerical algorithms describing the transition between the grid model and the mesh-free model are developed and the existing techniques of finite difference schemes for equidistant grids are extended to non-equidistant, arbitrarily shaped, convex four-point meshes. The modelling process is described, and both the numerical approximation and the algorithms are discussed. Applications in different technical devices show the flexibility of the method.
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  • 27
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 77-84 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Series function expansion algorithms of the time-domain analysis of boundary value problems are discussed. Electromagnetic fields inside a structure under investigation are expanded into series of basis functions and the expansion coefficients are found by means of the Galerkin method. The numerical cost of algorithms is discussed and a cost efficient approach is proposed for formulations using sine and cosine expansion functions. Compared with conventional time-domain methods the algorithms described show the time evolution of the expansion coefficients rather than the samples of a physical continuum at discrete nodes.
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  • 28
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. ii 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
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    Topics: Electrical Engineering, Measurement and Control Technology
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  • 29
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 189-199 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A rigorous technique for studying a thin wire circular loop antenna excited by a magnetic frill is developed. The exact kernel is derived and used to improve the accuracy. The scheme is applicable to small as well as large loops. Results obtained are nearly indistinguishable from those determined by the Fourier expansion method for non-resonant loops. A disagreement of 2 per cent is generally observed when the loop is close to reasonant for βb 〉 2. Compared with the conventional numerical method where a loop is represented by a polygon of straight wires, the present scheme is much faster and more accurate. Extension of this method to cover an antenna system of arbitrarily oriented loops intermingled with straight wires can be easily achieved.
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  • 30
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994) 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
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  • 31
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 239-252 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Simulation results for a n+-n-n+ two-valley semiconductor device obtained by use of a shock capturing numerical agorithm are presented. The one-dimensional problem is modelled by two systems of Euler equations connected by their source terms, and the Poisson equation. The resulting system of seven equations is hyperbolic and non-linear, and it is a great problem to find an adequate numerical approximation of its time-dependent discontinuities. There are additional complications due to the stiffness of the source terms.The numerical method used in this paper is first-order acurate in time but of high spatial order in regions of smoothness. Before the method is applied, the system has to be transformed to a characteristic form. The adopted shock capturing algorithm enables the choice of the order of the accuracy by the appropriate choice of the reconstruction polynomial. Reconstructions of the second and fourth order are tested and some numerical results are presented. Because of the stiffness of the source terms, the sixth-order accurate scheme breaks down. The results presented, and especially the response obtained of the structure to the step and periodic applied voltage, prove the correctness of the used schemes.
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  • 32
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 283-304 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: An algorithm is developed to evaluate the responses of discontinuous coplanar strip-lines excited by external electromagnetic fields. The algorithm uses the cascade chain matrix method which employs the distributed circuit parameters to model the external field coupling to the line and it is applicable to most commonly encountered discontinuities in microwave integrated circuit interconnects on lossy substrates. A general CAD program is developed based on this model and it is applied to realistic coplanar strip-line interconnections with geometric and resistive discontinuities to illustrate the capabilities of the algorithm. These interconnect models are selected from a practical microwave integrated circuit design. Simplicity and fast speed of the algorithm enable computer-aided analysis of externally induced electromagnetic noise in integrated circuits to be carried out. The effects of dielectric losses in the integrated circuit substrates and the discontinuities in the conducting tracks on the wave coupling are investigated in isolation.
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  • 33
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 329-342 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The finite element method (FEM) with local absorbing boundary conditions has been recently applied to compute electromagnetic scattering from large 3-D geometries. In this paper, we present details pertaining to code implementation and optimization. Various types of sparse matrix storage schemes are discussed and their performance is examined in terms of vectorization and net storage requirements. The system of linear equations is solved using a preconditioned biconjugate gradient (BCG) algorithm and a fairly detailed study of existing point and block preconditioners (diagonal and incomplete LU) is carried out. A modified ILU preconditioning scheme is also introducted which works better than the traditional version for our matrix systems. The parallelization of the iterative sparse solver and the matrix generation/assembly as implemented on the KSR1 multiprocessor is described and the interprocessor communication patterns are analysed in detail. Near-linear speed-up is obtained for both the iterative solver and the matrix generation/assembly phases. Results are presented for a problem having 224,476 unknowns and validated by comparison with measured data.
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  • 34
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 371-372 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 35
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 357-370 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The calculation of potentials in homogeneous and isotropic media by the boundary element method has the advantage that a harmonic solution of Laplace's equation is obtained for given approximated boundary conditions. The technique leads to the solution of linear systems with full matrices of dimension 1000-10,000 for medium- and large-sized three-dimensional problems, An efficient solution procedure of the linear systems is required.While the iterative solution of the large and sparse linear systems arising from the finite difference or the finite element method is well documented, the systems resulting from the boundary element method are typically solved by direct methods. However, in many cases an iterative solver needs far fewer operations to achieve a sufficient accuracy. Importantly, there are many alternative methods, each of them well suited for different types of problem.Here, we provide an overview of state-of-the-art iterative solvers. We will discuss the particular methods that have been successfully applied to systems arising from field calculations in the high-voltage engineering by the boundary element method. The selection of appropriate methods is discussed. We demonstrate that iterative solutions can be much faster than direct solvers with regards to the number of operations. Furthermore, these solvers are optimally suited for today's supercomputers because they can be efficiently vectorized and parallelized.
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  • 36
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 407-418 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper provides details of a widely applicable technique of hybrid modelling of thermal and particle diffusion which can help to reduce computational load in explicit formulation. The undesirable effects of artificial boundaries, which are introduced when a simulation is truncated or when an expanding mesh is used, can be eliminated by the use of discrete Green's functions. The technique can also be applied to problems involving infinite or near-infinite domains or problems where a complex thermal region is embedded within a larger, more simply described domain.
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  • 37
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 179-188 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A convex hexahedral TLM mesh of arbitrary shape is presented and the transmission-line matrix method extended to any non-orthogonal configuration. The novel mesh constitutes a natural generalization of Johns' condensed node. The associated TLM process is analysed and reconstructed as a genuine finite difference time-domain algorithm. Nodal S-parameters are derived from discretized Maxwell's equations and canonical stability criteria yield the TLM timestep. Unitarity is discussed and energy conservation confirmed in the non-conductive case.A given block-diagonal representation of the S-matrix restrains processing time per node and iteration within the range of traditional methods. The shortcomings of the rigid classical grid, as the need for inaccurate staircasing approximations, are, however, ruled out.Our analysis takes advantage of the recently developed propagator integral approach.
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  • 38
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 201-207 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The existing treatment of an instantaneous endothermic change of state is extended to deal both with exothermic effects and with first order Arrhenius changes. These extended treatments are used to model complex changes of phase occurring during the firing of ball clay and china clay, both of which are constitutents of the slip used in the production of vitreous china ware. The adequacy of the treatments is investigated for both clays by comparing a TLM simulation of a DSC (differential scanning calorimetry) experiment with measurements made during the experiment.
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  • 39
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 321-328 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The paper describes and compares the wave-chain and transmission matrix approaches to the calculation of transfer-function coefficients for ladder circuits (semi-symbolic analysis). It is found that the wave-chain matrix approach can be computationally more efficient.
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  • 40
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 343-355 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: To make possible the application of the three-dimensional finite element method to electrically large problems, it is combined with the analytical solutions of arbitrary large cavity with aperture. In this paper, detailed analysis for this hybrid method is presented. The element matrices necessary for coupling the finite element method to analytical solutions are given. The proposed hybrid method significantly reduces the number of unknown since only the inhomogeneity needs to be discretized. Thus computer memory and storage demands are reduced. In addition. This hybrid method employs the edge element which is not expected to produce spurious solutions. Also, the formulation presented in this paper preserves the sparsity of the finite element matrix, and does not require any matrix inversion. This new hybrid method is used to compute the field distributions in various partially filled rectangular enclosure. The results match well with the pure edgebased finite element method and analytical solutions.
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  • 41
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 377-398 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Field computations by mathematical and numerical methods are presented in the time and frequency domain. The techniques used are discretization and modal expansion. The effects of modelling and frequency range on the accuracy and calculation requirements are investigated and discussed. By way of application, several results of RF-filter designs are presented, where these methods have been implemented in CAD programs.
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  • 42
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 453-453 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 43
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 1-14 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Variational boundary element formulations are developed. Two functionals based on the dual and complementary energy approach are considered, which provide the upper and lower bound of the solution. Calculated examples of electrostatic fields are demonstrated for their field distributions and capacitances. Validity and the solution accuracy are discussed in comparison with the conventional boundary element solution.
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  • 44
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 25-33 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The method of effective penetration depth is used to produce a novel scalar or polarized finite difference approach for the solution of optical rib waveguide field problems. The new method is quicker than previous finite difference approaches and requires less computer memory. Propagation constant values are presented for a range of semiconductor rib waveguides and are found to be indistinguishable from benchmark results produced using earlier methods of analysis. A simple polarization correction formula recently derived is confirmed by utilizing the good accuracy of these results. This enables discussion of the relationship between quasi-TE, quasi-TM and scalar modes, and a further substantial reduction of the cpu time.
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  • 45
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 69-74 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: The application of multigrid techniques to the computation of the static solutions of electromagnetic field problems governed by Laplace's equation is described. This technique is compared with the conventional successive over-relaxation (SOR) method for solving finite difference problems. In contrast to SOR, the number of iterations of multigrid needed to achieve convergence is largely independent of the grid size. It is shown that the relative performance of multigrid is excellent on large grids where the number of iterations of SOR needed to achieve convergence becomes prohibitively large. The technique is illustrated by applying a parallel implementation of multigrid to find a quasistatic solution of a boxed microstrip problem.
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  • 46
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 85-97 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: A new approach to efficiently compute the low-frequency eigenmodes of a time-domain model approximating a linear physical system is proposed. The method is based on principles known from digital signal processing, in particular from parametic spectrum estimation, so it is not surprising that the achievable accuracy is much higher than the accuracy of the usual non-parametric discrete Fourier transform approach. The algorithm works in the general lossy case even for a very large number of unknowns and can easily be extended to calculate steady-state solutions under sinusoidal excitations for several different frequencies simultaneously.
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  • 47
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 99-125 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: In this paper we demonstrate the use of differential equations by means of an example from network analysis and show that differential/algebraic equations (DAE), rather than explicit ordinary differential equations (ODE), are more suitable for the description of electrical systems and networks. The main ideas of numerical integration of ODEs are presented. We consider this material from the point of view of replacing the ODE by a difference equation (DE). In particular, the relationship between the ODE and the associated DE is discussed. In the last Section the application of integration methods for OEDs upon DAEs and its difficulties are discussed. The paper is intended as a review; but a few new results are also included.
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  • 48
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994) 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
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    Topics: Electrical Engineering, Measurement and Control Technology
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  • 49
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 141-153 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Applying the method of moments to Maxwell's equations, Yee's two-dimensional FDTD scheme with central difference approximations and the two-dimensional TLM method are dervied from first principles of field theory. By comparing the eigenvalues of the two methods, the differences between two-dimensional FDTD and TLM are illustrated.
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  • 50
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 225-238 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Transverse transmission concepts in the Fourier transmission domain for multilayer planar transmission medium are presented. This complete transverse transmission theory (TTT) is found to be a superset of different Fourier-transform-based numerical techniques widely used in guided wave analysis, namely the modematching method and the spectral-domain approach. The features of the theory are: the expansion of field quantities in longitudinal section (LSE/LSM) modes, the concept of rotation of the transverse field vectors, and a comprehnsive algorithm using recursive matrix standard form. It is shown that the mode-matching method and spectral-domain approach are generally equivalent except for the last step of imposing the final boundary conditions, and can therefore be summarized in a unified theory within the framework of TTT. In addition, a new parameter, the polarization coefficient, has been introduced to describe the field polarization of the guided wave in a quantitative manner. It is believed that the present theory will help us to gain more insight into hybrid mode propagation in multilayer planar circuits.
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  • 51
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 267-281 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: This paper considers the adaptation of drift-diffusion device simulation methodology to study Auger-recombination-induced hot electron transport characteristics in InGaAsP/InP double heterostructure laser diodes. In order to model the transport behaviour of the Auger hot electrons, we decompose the conventional electron current continuity equation into two components, with one for the Auger hot electrons and the other for the low-energy electrons. These equations, which use the energy relaxation time parameter to model the dynamics of the Auger hot electrons, are then coupled with the hole current continuity equation and the Poisson equation to obtain self-consistent solutions. Results from the case studies of one-dimensional N-p-P InGaAsP/InP double heterojunction laser diodes with material composition corresponding to 1·3 μm and 1·55 μm wavelength emissions are presented. We have observed that hot electrons generated through Auger recombination inside the active region can spread into both the N- and the P-InP cladding layers. Within the drift-diffusion framework, it is demonstrated that the hot electron concentration in the N-InP cladding layer can be five orders of magnitude higher than that in the P-InP cladding layer. Because energy transport of the hot electrons in not modelled under the drift-diffusion approximation, the simulated results are discussed to highlight some of the possible limitations in using drift-diffusion physics to study Auger hot electron transport behaviour. The importance of taking energy transport into account is emphasized.
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  • 52
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994), S. 307-307 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology
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  • 53
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    International Journal of Numerical Modelling: Electronic Networks, Devices and Fields 7 (1994) 
    ISSN: 0894-3370
    Keywords: Engineering ; Electrical and Electronics Engineering
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  • 54
    Publication Date: 1994-02-25
    Description: Activation of the serine-threonine kinase p34cdc2 at an inappropriate time during the cell cycle leads to cell death that resembles apoptosis. Premature activation of p34cdc2 was shown to be required for apoptosis induced by a lymphocyte granule protease. The kinase was rapidly activated and tyrosine dephosphorylated at the initiation of apoptosis. DNA fragmentation and nuclear collapse could be prevented by blocking p34cdc2 activity with excess peptide substrate, or by inactivating p34cdc2 in a temperature-sensitive mutant. Premature p34cdc2 activation may be a general mechanism by which cells induced to undergo apoptosis initiate the disruption of the nucleus.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shi, L -- Nishioka, W K -- Th'ng, J -- Bradbury, E M -- Litchfield, D W -- Greenberg, A H -- New York, N.Y. -- Science. 1994 Feb 25;263(5150):1143-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8108732" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; *Apoptosis ; CDC2 Protein Kinase/*metabolism ; DNA Damage ; Deoxyribonucleases/pharmacology ; Enzyme Activation ; Enzyme Induction ; Membrane Glycoproteins/pharmacology ; Mice ; Mitosis ; Molecular Sequence Data ; Perforin ; Phosphorylation ; Pore Forming Cytotoxic Proteins ; Serine Endopeptidases/pharmacology ; Tumor Cells, Cultured
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 55
    Publication Date: 1994-05-20
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Patience, C -- McKnight, A -- Clapham, P R -- Boyd, M T -- Weiss, R A -- Schulz, T F -- G117/547/Medical Research Council/United Kingdom -- New York, N.Y. -- Science. 1994 May 20;264(5162):1159-60; author reply 1162-5.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7909960" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Antigens, CD4/*physiology ; Antigens, Differentiation, T-Lymphocyte/*physiology ; Base Sequence ; Cats ; Cell Line ; Dipeptidyl Peptidase 4 ; HIV-1/*physiology ; Humans ; Mink ; Molecular Sequence Data
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 56
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-10-14
    Description: An activity that severs stable microtubules is thought to be involved in microtubule reorganization during the cell cycle. Here, a 48-kilodalton microtubule-severing protein was purified from Xenopus eggs and identified as translational elongation factor 1 alpha (EF-1 alpha). Bacterially expressed human EF-1 alpha also displayed microtubule-severing activity in vitro and, when microinjected into fibroblasts, induced rapid and transient fragmentation of cytoplasmic microtubule arrays. Thus, EF-1 alpha, an essential component of the eukaryotic translational apparatus, appears to have a second role as a regulator of cytoskeletal rearrangements.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shiina, N -- Gotoh, Y -- Kubomura, N -- Iwamatsu, A -- Nishida, E -- New York, N.Y. -- Science. 1994 Oct 14;266(5183):282-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Genetics and Molecular Biology, Kyoto University, Japan.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7939665" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/pharmacology ; Amino Acid Sequence ; Animals ; Base Sequence ; Cell Line ; Guanosine Triphosphate/analogs & derivatives/metabolism ; Humans ; Microtubules/drug effects/*metabolism ; Molecular Sequence Data ; Molecular Weight ; Oocytes ; Peptide Elongation Factor 1 ; Peptide Elongation Factors/chemistry/isolation & purification/*physiology ; Rats ; Recombinant Proteins/pharmacology ; Ribonucleoproteins/chemistry/isolation & purification/*physiology ; Sepharose/analogs & derivatives/metabolism ; Xenopus laevis
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 57
    Publication Date: 1994-05-13
    Description: In Drosophila, the misexpression or altered activity of genes from the bithorax complex results in homeotic transformations. One of these genes, abd-A, normally specifies the identity of the second through fourth abdominal segments (A2 to A4). In the dominant Hyperabdominal mutations (Hab), portions of the third thoracic segment (T3) are transformed toward A2 as the result of ectopic abd-A expression. Sequence analysis and deoxyribonuclease I footprinting demonstrate that the misexpression of abd-A in two independent Hab mutations results from the same single base change in a binding site for the gap gene Kruppel protein. These results establish that the spatial limits of the homeotic genes are directly regulated by gap gene products.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shimell, M J -- Simon, J -- Bender, W -- O'Connor, M B -- New York, N.Y. -- Science. 1994 May 13;264(5161):968-71.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Biology and Biochemistry, University of California, Irvine 92717.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7909957" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Binding Sites ; DNA-Binding Proteins/genetics/metabolism ; *Drosophila Proteins ; Drosophila melanogaster/embryology/*genetics ; Enhancer Elements, Genetic/*genetics ; Gene Expression Regulation ; *Genes, Homeobox ; Genes, Insect ; Kruppel-Like Transcription Factors ; Molecular Sequence Data ; *Nuclear Proteins ; *Point Mutation ; Proteins/*genetics ; Regulatory Sequences, Nucleic Acid ; *Repressor Proteins ; Transcription Factors/genetics/metabolism
    Print ISSN: 0036-8075
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 58
    Publication Date: 1994-12-02
    Description: The nucleoli of vertebrate cells contain a number of small RNAs that are generated by the processing of intron fragments of protein-coding gene transcripts. The host gene (UHG) for intro-encoded human U22 is unusual in that it specifies a polyadenylated but apparently noncoding RNA. Depletion of U22 from Xenopus oocytes by oligonucleotide-directed ribonuclease H targeting prevented the processing of 18S ribosomal RNA (rRNA) at both ends. The appearance of 18S rRNA was restored by injection of in vitro-synthesized U22 RNA. These results identify a cellular function for an intron-encoded small RNA.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tycowski, K T -- Shu, M D -- Steitz, J A -- GM26154/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Dec 2;266(5190):1558-61.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06536.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7985025" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Blotting, Northern ; Cell Nucleolus/*chemistry ; Humans ; *Introns ; Molecular Sequence Data ; Oligonucleotide Probes ; Oocytes/metabolism ; RNA Precursors/*metabolism ; RNA Processing, Post-Transcriptional ; RNA, Nuclear/chemistry/*genetics/*physiology ; RNA, Ribosomal, 18S/*metabolism ; RNA, Small Nuclear/chemistry/*genetics/*physiology ; Xenopus
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 59
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-11-25
    Description: The splicing of group II introns occurs in two steps involving substrates with different chemical configurations. The question of whether these two steps are catalyzed by a single or two separate active sites is a matter of debate. Here, certain bases and phosphate oxygen atoms at conserved positions in domain V of a group II self-splicing intron are shown to be required for catalysis of both splicing steps. These results show that the active sites catalyzing the two steps must, at least, share common components, ruling out the existence of two completely distinct active sites in group II introns.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chanfreau, G -- Jacquier, A -- New York, N.Y. -- Science. 1994 Nov 25;266(5189):1383-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Unite de Genetique Moleculaire des Levures, URA 1149 du CNRS, Departement de Biologie Moleculaire, Institut Pasteur, Paris, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973729" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding Sites ; Catalysis ; Electron Transport Complex IV/genetics ; Electrophoresis, Polyacrylamide Gel ; Exons ; *Introns ; Molecular Sequence Data ; Nucleic Acid Conformation ; *RNA Splicing ; RNA, Fungal/chemistry/*genetics ; Saccharomyces cerevisiae/enzymology/genetics ; Thionucleotides/genetics
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  • 60
    Publication Date: 1994-10-14
    Description: The rate at which the TATA-binding protein (TBP) interacts with the TATA element and promotes transcription by RNA polymerase II was determined in yeast cells. A TBP derivative with altered TATA-element specificity was rapidly induced, and transcription from promoters with appropriately mutated TATA elements was measured. Without a functional activator protein, basal transcription was observed only after a lag of several hours. In contrast, GCN4-activated transcription occurred rapidly upon induction of the TBP derivative. These results suggest that accessibility of TBP to the chromatin template in vivo is rate limiting and that activation domains increase recruitment of TBP to the promoter.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Klein, C -- Struhl, K -- GM30186/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Oct 14;266(5183):280-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7939664" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Binding Sites ; Chromatin/metabolism ; Copper/pharmacology ; DNA-Binding Proteins/*metabolism ; Fungal Proteins/metabolism/pharmacology ; Hydro-Lyases/genetics ; Molecular Sequence Data ; Protein Kinases/metabolism/pharmacology ; *Saccharomyces cerevisiae Proteins ; *TATA Box ; TATA-Box Binding Protein ; Templates, Genetic ; Transcription Factors/*metabolism/pharmacology ; *Transcriptional Activation ; Yeasts/genetics
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  • 61
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-11-04
    Description: An activity in human cell extracts is described that repairs DNA with loops of five or more unpaired bases. Repair is strand-specific and is directed by a nick located 5' or 3' to the loop. This repair is observed in a colorectal cancer cell line that is devoid of a wild-type hMLH1 gene and is deficient in repair of mismatches. However, a cell line with deletions in both hMSH2 alleles is deficient in repair of both loops and mismatches. Defects in loop repair may be relevant to the repetitive-sequence instability observed in cancers and other hereditary diseases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Umar, A -- Boyer, J C -- Kunkel, T A -- New York, N.Y. -- Science. 1994 Nov 4;266(5186):814-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973637" target="_blank"〉PubMed〈/a〉
    Keywords: Adaptor Proteins, Signal Transducing ; Base Composition ; Base Sequence ; Carrier Proteins ; Cell Extracts ; Cell Line ; Colorectal Neoplasms/*genetics ; *DNA Repair ; DNA, Satellite/genetics/metabolism ; *DNA-Binding Proteins ; HeLa Cells ; Humans ; Molecular Sequence Data ; MutS Homolog 2 Protein ; Neoplasm Proteins/*genetics/physiology ; Nuclear Proteins ; Nucleic Acid Heteroduplexes/*metabolism ; Proto-Oncogene Proteins/*genetics/physiology ; Repetitive Sequences, Nucleic Acid ; Tumor Cells, Cultured
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  • 62
    Publication Date: 1994-08-19
    Description: The Xlsirts are a family of transcribed repeat sequence genes that do not code for protein. Xlsirt RNAs become localized to the vegetal cortex of Xenopus oocytes early in oogenesis, before the localization of the messenger RNA Vg1, which encodes a transforming growth factor-beta-like molecule involved in mesoderm formation, and coincident with the localization of Xcat2 transcripts, which encode a nanos-like molecule. Destruction of the localized Xlsirts by injection of antisense oligodeoxynucleotides into stage 4 oocytes resulted in the release of Vg1 transcripts but not Xcat2 transcripts from the vegetal cortex. Xlsirt RNAs, which may be a structural component of the vegetal cortex, are a crucial part of a genetic pathway necessary for the proper localization of Vg1 that leads to subsequent normal pattern formation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kloc, M -- Etkin, L D -- New York, N.Y. -- Science. 1994 Aug 19;265(5175):1101-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular Genetics, University of Texas, M.D. Anderson Cancer Center, Houston 77030.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7520603" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Cells, Cultured ; Glycoproteins/*genetics ; Molecular Sequence Data ; Oligonucleotides, Antisense/pharmacology ; Oogenesis ; RNA/*genetics ; RNA, Messenger/genetics/*metabolism ; RNA-Binding Proteins/genetics ; Repetitive Sequences, Nucleic Acid ; Transforming Growth Factor beta/genetics ; Xenopus ; *Xenopus Proteins ; Zinc Fingers
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  • 63
    Publication Date: 1994-06-24
    Description: Two ternary complexes of rat DNA polymerase beta (pol beta), a DNA template-primer, and dideoxycytidine triphosphate (ddCTP) have been determined at 2.9 A and 3.6 A resolution, respectively. ddCTP is the triphosphate of dideoxycytidine (ddC), a nucleoside analog that targets the reverse transcriptase of human immunodeficiency virus (HIV) and is at present used to treat AIDS. Although crystals of the two complexes belong to different space groups, the structures are similar, suggesting that the polymerase-DNA-ddCTP interactions are not affected by crystal packing forces. In the pol beta active site, the attacking 3'-OH of the elongating primer, the ddCTP phosphates, and two Mg2+ ions are all clustered around Asp190, Asp192, and Asp256. Two of these residues, Asp190 and Asp256, are present in the amino acid sequences of all polymerases so far studied and are also spatially similar in the four polymerases--the Klenow fragment of Escherichia coli DNA polymerase I, HIV-1 reverse transcriptase, T7 RNA polymerase, and rat DNA pol beta--whose crystal structures are now known. A two-metal ion mechanism is described for the nucleotidyl transfer reaction and may apply to all polymerases. In the ternary complex structures analyzed, pol beta binds to the DNA template-primer in a different manner from that recently proposed for other polymerase-DNA models.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pelletier, H -- Sawaya, M R -- Kumar, A -- Wilson, S H -- Kraut, J -- CA17374/CA/NCI NIH HHS/ -- ES06839/ES/NIEHS NIH HHS/ -- GM10928/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Jun 24;264(5167):1891-903.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California, San Diego 92093-0317.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7516580" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Binding Sites ; Crystallization ; Crystallography, X-Ray ; DNA/chemistry/metabolism ; DNA Polymerase I/*chemistry/metabolism ; DNA Primers/*chemistry/metabolism ; DNA-Directed RNA Polymerases/chemistry/metabolism ; Deoxycytosine Nucleotides/*chemistry/metabolism ; Dideoxynucleotides ; HIV Reverse Transcriptase ; Humans ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; RNA-Directed DNA Polymerase/chemistry/metabolism ; Rats ; Recombinant Proteins ; Templates, Genetic ; Thymine Nucleotides/chemistry/metabolism ; Viral Proteins ; Zidovudine/analogs & derivatives/chemistry/metabolism
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  • 64
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-06-17
    Description: Noninfectious, cytoplasmically transmissible viral double-stranded RNAs of the genus Hypovirus cause reduced virulence (hypovirulence) in the chestnut blight fungus Cryphonectria parasitica, providing the basis for virus-mediated biological control of a fungal disease. Synthetic transcripts corresponding to a full-length hypovirus RNA coding strand are infectious when introduced into fungal spheroplasts by electroporation. Hypovirus infections were readily established in Cryphonectria parasitica and in related fungal species not previously reported to harbor viruses. These results demonstrate the use of a synthetic mycovirus transcript to expand fungal host range, thereby broadening the potential application of virus-mediated hypovirulence to control fungal pathogenesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chen, B -- Choi, G H -- Nuss, D L -- New York, N.Y. -- Science. 1994 Jun 17;264(5166):1762-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Roche Institute of Molecular Biology, Roche Research Center, Nutley, NJ 07110.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8209256" target="_blank"〉PubMed〈/a〉
    Keywords: Ascomycota/genetics/*pathogenicity/physiology ; Base Sequence ; DNA, Complementary/genetics ; Electroporation ; Molecular Sequence Data ; Phenotype ; Plant Diseases ; RNA Viruses/*genetics/physiology ; RNA, Double-Stranded/*genetics ; RNA, Viral/*genetics ; Spheroplasts ; Transfection ; Virulence ; Virus Replication
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  • 65
    Publication Date: 1994-08-12
    Description: Strategies to cleave double-stranded DNA at specific DNA sites longer than those of restriction endonucleases (longer than 8 base pairs) have applications in chromosome mapping, chromosome cloning, and chromosome sequencing--provided that the strategies yield high DNA-cleavage efficiency and high DNA-cleavage specificity. In this report, the DNA-cleaving moiety copper:o-phenanthroline was attached to the sequence-specific DNA binding protein catabolite activator protein (CAP) at an amino acid that, because of a difference in DNA bending, is close to DNA in the specific CAP-DNA complex but is not close to DNA in the nonspecific CAP-DNA complex. The resulting CAP derivative, OP26CAP, cleaved kilobase and megabase DNA substrates at a 22-base pair consensus DNA site with high efficiency and exhibited no detectable nonspecific DNA-cleavage activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pendergrast, P S -- Ebright, Y W -- Ebright, R H -- GM41376/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Aug 12;265(5174):959-62.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, Rutgers University, New Brunswick, NJ 08855.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8052855" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Cyclic AMP Receptor Protein/*chemistry ; DNA/*chemistry/metabolism ; DNA-Binding Proteins/*chemistry ; Molecular Sequence Data ; Molecular Structure ; Nucleic Acid Conformation ; Phenanthrolines/*chemistry
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  • 66
    Publication Date: 1994-11-11
    Description: The venom of the funnel-web spider Agelenopsis aperta contains several peptides that paralyze prey by blocking voltage-sensitive calcium channels. Two peptides, omega-Aga-IVB (IVB) and omega-Aga-IVC (IVC), have identical amino acid sequences, yet have opposite absolute configurations at serine 46. These toxins had similar selectivities for blocking voltage-sensitive calcium channel subtypes but different potencies for blocking P-type voltage-sensitive calcium channels in rat cerebellar Purkinje cells as well as calcium-45 influx into rat brain synaptosomes. An enzyme purified from venom converts IVC to IVB by isomerizing serine 46, which is present in the carboxyl-terminal tail, from the L to the D configuration. Unlike the carboxyl terminus of IVC, that of IVB was resistant to the major venom protease. These results show enzymatic activities in A. aperta venom being used in an unprecedented strategy for coproduction of necessary neurotoxins that possess enhanced stability and potency.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Heck, S D -- Siok, C J -- Krapcho, K J -- Kelbaugh, P R -- Thadeio, P F -- Welch, M J -- Williams, R D -- Ganong, A H -- Kelly, M E -- Lanzetti, A J -- New York, N.Y. -- Science. 1994 Nov 11;266(5187):1065-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉NPS Pharmaceuticals Incorporated, Salt Lake City, Utah 84108.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973665" target="_blank"〉PubMed〈/a〉
    Keywords: Agatoxins ; Amino Acid Sequence ; Animals ; Base Sequence ; Calcium/metabolism ; Calcium Channel Blockers/chemistry/*metabolism/toxicity ; Calcium Channels/*metabolism ; Isomerases/metabolism ; Molecular Sequence Data ; *Protein Processing, Post-Translational ; Purkinje Cells/metabolism ; Rats ; Serine/*metabolism ; Spider Venoms/chemistry/enzymology/*metabolism/toxicity ; Stereoisomerism ; Structure-Activity Relationship ; Synaptosomes/metabolism
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  • 67
    Publication Date: 1994-11-25
    Description: Alteration of the human mismatch repair gene hMSH2 has been linked to the microsatellite DNA instability found in hereditary nonpolyposis colon cancer and several sporadic cancers. This microsatellite DNA instability is thought to arise from defective repair of DNA replication errors that create insertion-deletion loop-type (IDL) mismatched nucleotides. Here, it is shown that purified hMSH2 protein efficiently and specifically binds DNA containing IDL mismatches of up to 14 nucleotides. These results support a direct role for hMSH2 in mutation avoidance and microsatellite stability in human cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fishel, R -- Ewel, A -- Lee, S -- Lescoe, M K -- Griffith, J -- CA56542/CA/NCI NIH HHS/ -- GM31819/GM/NIGMS NIH HHS/ -- GM42342/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Nov 25;266(5189):1403-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Molecular Genetics, Markey Center for Molecular Genetics, University of Vermont School of Medicine, Burlington 05405.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973733" target="_blank"〉PubMed〈/a〉
    Keywords: Base Composition ; Base Sequence ; DNA Repair ; DNA, Satellite/*metabolism ; *DNA-Binding Proteins ; Humans ; Molecular Sequence Data ; MutS Homolog 2 Protein ; Nucleic Acid Conformation ; Nucleic Acid Heteroduplexes/metabolism ; Oligodeoxyribonucleotides/metabolism ; Proto-Oncogene Proteins/*metabolism
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  • 68
    Publication Date: 1994-08-26
    Description: Experimental autoimmune encephalomyelitis (EAE) is a cell-mediated autoimmune disease that serves as an animal model for multiple sclerosis. Oral administration of myelin basic protein (MBP) suppresses EAE by inducing peripheral tolerance. T cell clones were isolated from the mesenteric lymph nodes of SJL mice that had been orally tolerized to MBP. These clones were CD4+ and were structurally identical to T helper cell type 1 (TH1) encephalitogenic CD4+ clones in T cell receptor usage, major histocompatibility complex restriction, and epitope recognition. However, they produced transforming growth factor-beta with various amounts of interleukin-4 and interleukin-10 and suppressed EAE induced with either MBP or proteolipid protein. Thus, mucosally derived TH2-like clones induced by oral antigen can actively regulate immune responses in vivo and may represent a different subset of T cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chen, Y -- Kuchroo, V K -- Inobe, J -- Hafler, D A -- Weiner, H L -- AR/A143220/AR/NIAMS NIH HHS/ -- NS29352/NS/NINDS NIH HHS/ -- NS30843/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1994 Aug 26;265(5176):1237-40.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7520605" target="_blank"〉PubMed〈/a〉
    Keywords: Administration, Oral ; Amino Acid Sequence ; Animals ; CD4-Positive T-Lymphocytes/*immunology ; Clone Cells ; Encephalomyelitis, Autoimmune, Experimental/*immunology ; Epitopes/immunology ; *Immune Tolerance ; Interleukin-10/biosynthesis ; Interleukin-4/biosynthesis ; Lymph Nodes/immunology ; Major Histocompatibility Complex ; Mesentery/immunology ; Mice ; Molecular Sequence Data ; Myelin Basic Protein/administration & dosage/*immunology ; Myelin Proteins/immunology ; Myelin Proteolipid Protein ; Receptors, Antigen, T-Cell/immunology ; Transforming Growth Factor beta/biosynthesis
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  • 69
    Publication Date: 1994-09-02
    Description: As a step toward developing poliovirus as a vaccine vector, poliovirus recombinants were constructed by fusing exogenous peptides (up to 400 amino acids) and an artificial cleavage site for viral protease 3Cpro to the amino terminus of the viral polyprotein. Viral replication proceeded normally. An extended polyprotein was produced in infected cells and proteolytically processed into the complete array of viral proteins plus the foreign peptide, which was excluded from mature virions. The recombinants retained exogenous sequences through successive rounds of replication in culture and in vivo. Infection of animals with recombinants elicited a humoral immune response to the foreign peptides.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Andino, R -- Silvera, D -- Suggett, S D -- Achacoso, P L -- Miller, C J -- Baltimore, D -- Feinberg, M B -- AI22346/AI/NIAID NIH HHS/ -- AI35545/AI/NIAID NIH HHS/ -- RR00169/RR/NCRR NIH HHS/ -- New York, N.Y. -- Science. 1994 Sep 2;265(5177):1448-51.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Immunology, University of California, San Francisco.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8073288" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Antibodies, Bacterial/biosynthesis ; Antibodies, Viral/biosynthesis ; Antigens, Bacterial/genetics/immunology ; Antigens, Viral/genetics/immunology ; Base Sequence ; Cloning, Molecular ; *Genetic Engineering ; Genetic Vectors ; HeLa Cells ; Humans ; Macaca fascicularis ; Mice ; Mice, Transgenic ; Molecular Sequence Data ; Poliovirus/*genetics/immunology/physiology ; Poliovirus Vaccine, Oral/*genetics ; *Protein Biosynthesis ; Proteins/metabolism ; Recombinant Proteins/biosynthesis/metabolism ; Vaccines, Synthetic/genetics/*immunology ; Virus Replication
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  • 70
    Publication Date: 1994-11-11
    Description: For survival, embryonic motoneurons in vertebrates depend on as yet undefined neurotrophic factors present in the limb bud. Members of the neurotrophin family are currently the best candidates for such neurotrophic factors, but inactivation of their receptor genes leads to only partial loss of motoneurons, which suggests that other factors are involved. Glial cell line-derived neurotrophic factor (GDNF), originally identified as a trophic factor specific for dopaminergic neurons, was found to be 75-fold more potent than the neurotrophins in supporting the survival of purified embryonic rat motoneurons in culture. GDNF messenger RNA was found in the immediate vicinity of motoneurons during the period of cell death in development. In vivo, GDNF rescues and prevents the atrophy of facial motoneurons that have been deprived of target-derived survival factors by axotomy. GDNF may therefore be a physiological trophic factor for spinal motoneurons. Its potency and specificity in vitro and in vivo also make it a good candidate for treatment of motoneuron disease.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Henderson, C E -- Phillips, H S -- Pollock, R A -- Davies, A M -- Lemeulle, C -- Armanini, M -- Simmons, L -- Moffet, B -- Vandlen, R A -- Simpson LC corrected to Simmons, L -- Koliatsos, V E -- Rosenthal, A -- NS 10580/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1994 Nov 11;266(5187):1062-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉INSERM U.382, IBDM, Marseille, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973664" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Brain-Derived Neurotrophic Factor ; Cell Death ; Cell Survival/drug effects ; Cells, Cultured ; Ciliary Neurotrophic Factor ; Face/innervation ; Glial Cell Line-Derived Neurotrophic Factor ; Growth Inhibitors/pharmacology ; *Interleukin-6 ; Leukemia Inhibitory Factor ; Lymphokines/pharmacology ; Molecular Sequence Data ; Motor Neurons/*cytology/drug effects ; Muscle Fibers, Skeletal/*metabolism ; Nerve Growth Factors/analysis/biosynthesis/genetics/*pharmacology ; Nerve Tissue Proteins/*analysis/biosynthesis/genetics/*pharmacology ; Neurons, Afferent/cytology/drug effects ; Peripheral Nerves/*metabolism ; RNA, Messenger/analysis/genetics ; Rats ; Schwann Cells/metabolism
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  • 71
    Publication Date: 1994-05-13
    Description: In Drosophila and human cells, the TATA binding protein (TBP) of the transcription factor IID (TFIID) complex is tightly associated with multiple subunits termed TBP-associated factors (TAFs) that are essential for mediating regulation of RNA polymerase II transcription. The Drosophila TAFII150 has now been molecularly cloned and biochemically characterized. The deduced primary amino acid sequence of dTAFII150 reveals a striking similarity to the essential yeast gene, TSM-1. Furthermore, like dTAFII150, the TSM-1 protein is found associated with the TBP in vivo, thus identifying the first yeast homolog of a TAF associated with TFIID. Both the product of TSM-1 and dTAFII150 bind directly to TBP and dTAFII250, demonstrating a functional similarity between human and yeast TAFs. Surprisingly, DNA binding studies indicate that purified recombinant dTAFII150 binds specifically to DNA sequences overlapping the start site of transcription. The data demonstrate that at least one of the TAFs is a sequence-specific DNA binding protein and that dTAFII150 together with TBP are responsible for TFIID interactions with an extended region of the core promoter.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Verrijzer, C P -- Yokomori, K -- Chen, J L -- Tjian, R -- New York, N.Y. -- Science. 1994 May 13;264(5161):933-41.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, University of California, Berkeley 94720-3202.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8178153" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Cloning, Molecular ; DNA/*metabolism ; DNA-Binding Proteins/chemistry/genetics/*metabolism ; Drosophila ; *Drosophila Proteins ; Genes, Fungal ; Genes, Insect ; Histone Acetyltransferases ; Humans ; Molecular Sequence Data ; Nuclear Proteins/metabolism ; *Promoter Regions, Genetic ; RNA Polymerase II/metabolism ; Recombinant Proteins/metabolism ; Saccharomyces cerevisiae/genetics ; *Saccharomyces cerevisiae Proteins ; Sequence Alignment ; TATA Box ; *TATA-Binding Protein Associated Factors ; TATA-Box Binding Protein ; Transcription Factor TFIID ; Transcription Factors/chemistry/genetics/*metabolism
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  • 72
    Publication Date: 1994-12-16
    Description: Representational difference analysis was used to isolate unique sequences present in more than 90 percent of Kaposi's sarcoma (KS) tissues obtained from patients with acquired immunodeficiency syndrome (AIDS). These sequences were not present in tissue DNA from non-AIDS patients, but were present in 15 percent of non-KS tissue DNA samples from AIDS patients. The sequences are homologous to, but distinct from, capsid and tegument protein genes of the Gammaherpesvirinae, herpesvirus saimiri and Epstein-Barr virus. These KS-associated herpesvirus-like (KSHV) sequences appear to define a new human herpesvirus.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Chang, Y -- Cesarman, E -- Pessin, M S -- Lee, F -- Culpepper, J -- Knowles, D M -- Moore, P S -- New York, N.Y. -- Science. 1994 Dec 16;266(5192):1865-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pathology, College of Physicians and Surgeons, Columbia University, New York, NY 10032.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7997879" target="_blank"〉PubMed〈/a〉
    Keywords: Acquired Immunodeficiency Syndrome/*complications ; Amino Acid Sequence ; Base Composition ; Base Sequence ; Blotting, Southern ; Cloning, Molecular ; DNA, Viral/*analysis/chemistry/genetics ; Female ; Herpesviridae/*genetics ; Herpesvirus 2, Saimiriine/genetics ; Herpesvirus 4, Human/genetics ; Humans ; Male ; Molecular Sequence Data ; Nucleic Acid Hybridization ; Open Reading Frames ; Polymerase Chain Reaction ; Retrospective Studies ; Sarcoma, Kaposi/etiology/*virology ; Sequence Homology, Amino Acid
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  • 73
    Publication Date: 1994-11-11
    Description: Signals mediated by the T cell receptor (TCR) are required for thymocyte maturation and selection. To examine the role of TCR zeta chain signals in development, TCR expression was restored in zeta-deficient mice with transgenic zeta chains that partially or completely lacked sequences required for signal transduction. The zeta chain played a role in thymic development by promoting TCR surface expression, but zeta-mediated signals were not essential because TCRs that contained signaling-deficient zeta chains promoted T cell maturation and transduced signals associated with thymic selection.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shores, E W -- Huang, K -- Tran, T -- Lee, E -- Grinberg, A -- Love, P E -- New York, N.Y. -- Science. 1994 Nov 11;266(5187):1047-50.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Hematologic Products, Food and Drug Administration, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7526464" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Antigens, CD/analysis/genetics ; Antigens, CD4/analysis ; Antigens, CD5 ; Antigens, CD8/analysis ; Antigens, Differentiation, T-Lymphocyte/analysis ; *DNA-Binding Proteins ; Down-Regulation ; Gene Expression ; *Homeodomain Proteins ; Lectins, C-Type ; Lymph Nodes/immunology ; Membrane Proteins/genetics/*physiology ; Mice ; Mice, Transgenic ; Molecular Sequence Data ; Proteins/genetics ; RNA, Messenger/genetics/metabolism ; Receptors, Antigen, T-Cell/genetics/*physiology ; Signal Transduction ; T-Lymphocytes/cytology/*immunology ; Thymus Gland/immunology
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  • 74
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-08-05
    Description: The microinjection of messenger RNA encoding the eukaryotic translation initiation factor 4E (eIF-4E) into early embryos of Xenopus laevis leads to the induction of mesoderm in ectodermal explants. This induction occurs without a stimulation of overall protein synthesis and is blocked by the co-expression of a dominant negative mutant of the proto-oncogene ras or a truncated activin type II receptor. Although other translation factors have been studied in vertebrate and invertebrate embryos, none have been shown to play a direct role in development. The results here suggest a mechanism for relaying and amplifying signals for mesoderm induction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Klein, P S -- Melton, D A -- New York, N.Y. -- Science. 1994 Aug 5;265(5173):803-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, MA 02138.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8047887" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Eukaryotic Initiation Factor-1/physiology ; Eukaryotic Initiation Factor-4E ; Gene Expression Regulation/physiology ; Mesoderm/metabolism/*physiology ; Molecular Sequence Data ; Peptide Initiation Factors/genetics/*physiology ; RNA, Messenger ; Xenopus laevis/*embryology
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  • 75
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-11-11
    Description: Long-tailed manakins mate in leks and cooperate in multiyear male-male partnerships. An alpha male is responsible for virtually all mating, whereas a beta male assists in the courtship displays. Such altruism by the beta male poses a problem for evolutionary theory because most theoretical treatments and empirical examples of cooperative behavior involve kin selection or reciprocity. Here it is shown that alpha and beta partners are not relatives and that reciprocity is not involved. Instead, direct, though long-delayed benefits to beta males are demonstrated, which include rare copulations, ascension to alpha status, and female lek fidelity. These benefits maintain this unusual form of male-male cooperation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McDonald, D B -- Potts, W K -- New York, N.Y. -- Science. 1994 Nov 11;266(5187):1030-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Archbold Biological Station, Lake Placid, FL 33852-2057.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973654" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Animals ; Base Sequence ; Birds/genetics/*physiology ; *Cooperative Behavior ; Copulation ; Female ; Heterozygote ; Male ; Molecular Sequence Data ; Polymerase Chain Reaction ; *Sexual Behavior, Animal
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  • 76
    facet.materialart.
    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-03-25
    Description: Significant opportunities and challenges exist in the creation and characterization of biomaterials. Materials have been designed for contact with blood, as replacements for soft and hard tissues, as adhesives, and as dental materials. Current methods of synthesis and characterization of these materials are outlined. Approaches for controlling the interface between tissue and biomaterials and ways in which the engineered materials may contribute to medicine are considered.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Peppas, N A -- Langer, R -- GM25810/GM/NIGMS NIH HHS/ -- GM43337/GM/NIGMS NIH HHS/ -- GM45027/GM/NIGMS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1994 Mar 25;263(5154):1715-20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Chemical Engineering, Purdue University, West Lafayette, IN 47907-1283.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8134835" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; *Biocompatible Materials/chemical synthesis/chemistry ; Dental Materials ; Drug Carriers ; Humans ; Materials Testing ; Molecular Sequence Data ; Prostheses and Implants ; Protein Engineering
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  • 77
    Publication Date: 1994-06-24
    Description: A 175-kilodalton erythrocyte binding protein, EBA-175, of the parasite Plasmodium falciparum mediates the invasion of erythrocytes. The erythrocyte receptor for EBA-175 is dependent on sialic acid. The domain of EBA-175 that binds erythrocytes was identified as region II with the use of truncated portions of EBA-175 expressed on COS cells. Region II, which contains a cysteine-rich motif, and native EBA-175 bind specifically to glycophorin A, but not to glycophorin B, on the erythrocyte membrane. Erythrocyte recognition of EBA-175 requires both sialic acid and the peptide backbone of glycophorin A. The identification of both the receptor and ligand domains may suggest rational designs for receptor blockade and vaccines.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Sim, B K -- Chitnis, C E -- Wasniowska, K -- Hadley, T J -- Miller, L H -- New York, N.Y. -- Science. 1994 Jun 24;264(5167):1941-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Malaria Research, National Institutes of Health, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8009226" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Antigens, Protozoan ; Base Sequence ; Binding Sites ; Carrier Proteins/genetics/*metabolism ; Cell Line ; Erythrocytes/metabolism/*parasitology ; Glycopeptides/chemistry/metabolism ; Glycophorin/chemistry/*metabolism ; Molecular Sequence Data ; Plasmodium falciparum/*metabolism ; Protozoan Proteins/genetics/*metabolism ; Recombinant Fusion Proteins/metabolism ; Sialic Acids/*metabolism
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  • 78
    Publication Date: 1994-03-25
    Description: Fas is an apoptosis-signaling receptor molecule on the surface of a number of cell types. Molecular cloning and nucleotide sequence analysis revealed a human Fas messenger RNA variant capable of encoding a soluble Fas molecule lacking the transmembrane domain because of the deletion of an exon encoding this region. The expression of soluble Fas was confirmed by flow cytometry and immunocytochemical analysis. Supernatants from cells transfected with the variant messenger RNA blocked apoptosis induced by the antibody to Fas. Levels of soluble Fas were elevated in patients with systemic lupus erythematosus, and mice injected with soluble Fas displayed autoimmune features.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Cheng, J -- Zhou, T -- Liu, C -- Shapiro, J P -- Brauer, M J -- Kiefer, M C -- Barr, P J -- Mountz, J D -- P01 AR03555/AR/NIAMS NIH HHS/ -- P50 AI23694/AI/NIAID NIH HHS/ -- P60 AR20614/AR/NIAMS NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1994 Mar 25;263(5154):1759-62.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉University of Alabama at Birmingham.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7510905" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Antibodies/immunology ; Antigens, CD95 ; Antigens, Surface/chemistry/genetics/immunology/*physiology ; *Apoptosis ; Arthritis, Rheumatoid/blood ; Base Sequence ; Cell Line ; Cell Membrane/chemistry ; Humans ; Lupus Erythematosus, Systemic/blood ; Mice ; Molecular Sequence Data ; RNA, Messenger/genetics ; Solubility ; T-Lymphocyte Subsets/immunology ; Transfection
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  • 79
    Publication Date: 1994-11-04
    Description: Transcription terminators recognized by several RNA polymerases include a DNA segment encoding uridine-rich RNA and, for bacterial RNA polymerase, a hairpin loop located immediately upstream. Here, mutationally altered Escherichia coli RNA polymerase enzymes that have different termination efficiencies were used to show that the extent of transcription through the uridine-rich encoding segment is controlled by the substrate concentration of nucleoside triphosphate. This result implies that the rate of elongation determines the probability of transcript release. Moreover, the position of release sites suggests an important spatial relation between the RNA hairpin and the boundary of the terminator.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉McDowell, J C -- Roberts, J W -- Jin, D J -- Gross, C -- New York, N.Y. -- Science. 1994 Nov 4;266(5186):822-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, NY 14853.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7526463" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; DNA-Directed RNA Polymerases/genetics/*metabolism ; Escherichia coli/enzymology/genetics ; Molecular Sequence Data ; Mutation ; Nucleic Acid Conformation ; Nucleotides/metabolism ; RNA, Bacterial/*genetics/metabolism ; *Terminator Regions, Genetic ; *Transcription, Genetic ; Uridine Triphosphate/metabolism
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  • 80
    Publication Date: 1994-03-18
    Description: Engagement of antigen receptor complexes induces rapid activation of Src-family kinases and association with phosphatidylinositol-3' kinase (PI-3 kinase). Here it was found that the Src homology 3 (SH3) domain of Lyn and Fyn bound to a proline-rich region (residues 84 to 99) within the 85-kilodalton subunit (p85) of PI-3 kinase. The binding of SH3 to the purified kinase led to a five- to sevenfold increase in the specific activity of PI-3 kinase. Ligand-induced receptor stimulation activated PI-3 kinase, and this activation was blocked by a peptide containing residues 84 to 99 of p85. These data demonstrate a mechanism for PI-3 kinase activation and show that binding of SH3 domains to proline-rich target sequences can regulate enzymatic activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pleiman, C M -- Hertz, W M -- Cambier, J C -- A120519/PHS HHS/ -- A121768/PHS HHS/ -- A129903/PHS HHS/ -- New York, N.Y. -- Science. 1994 Mar 18;263(5153):1609-12.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Pediatrics, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8128248" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; B-Lymphocytes/*enzymology ; Enzyme Activation ; Lymphocyte Activation ; Mice ; Molecular Sequence Data ; Peptide Fragments/pharmacology ; Phosphatidylinositol 3-Kinases ; Phosphotransferases (Alcohol Group Acceptor)/chemistry/*metabolism ; Proline/chemistry ; Protein-Tyrosine Kinases/chemistry/*metabolism ; Proto-Oncogene Proteins/chemistry/*metabolism ; Proto-Oncogene Proteins c-fyn ; *src-Family Kinases
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  • 81
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-05-20
    Description: A predictive rule for protein folding is presented that involves two recurrent glycine-based motifs that cap the carboxyl termini of alpha helices. In proteins, helices that terminated in glycine residues were found predominantly in one of these two motifs. These glycine structures had a characteristic pattern of polar and apolar residues. Visual inspection of known helical sequences was sufficient to distinguish the two motifs from each other and from internal glycines that fail to terminate helices. These glycine motifs--in which the local sequence selects between available structures--represent an example of a stereochemical rule for protein folding.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Aurora, R -- Srinivasan, R -- Rose, G D -- GM 29458/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 May 20;264(5162):1126-30.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8178170" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Glycine/*chemistry ; Hydrogen Bonding ; Models, Molecular ; Molecular Sequence Data ; Mutation ; Oligopeptides/chemistry ; *Protein Folding ; *Protein Structure, Secondary
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  • 82
    Publication Date: 1994-12-09
    Description: Complete 16S-like ribosomal RNA coding regions were obtained from the fungal symbiont of five genera of attine (leaf-cutting) ants and two free-living fungi. Phylogenetic analyses with distance matrix, maximum likelihood, and parsimony methods revealed that the attine fungal symbionts are homobasidiomycetes in the order Agaricales. Comparison of the topology of the attine fungal symbiont phylogenetic tree with a tree based on attine ant morphology revealed a congruent branching pattern of the more derived attine ants and their fungal symbionts. The parallel branching pattern suggests a long-term coevolution of derived leaf-cutting attine ants and their fungal symbionts.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hinkle, G -- Wetterer, J K -- Schultz, T R -- Sogin, M L -- GM32964/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Dec 9;266(5191):1695-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Marine Biological laboratory, Woods Hole, MA 02543.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7992052" target="_blank"〉PubMed〈/a〉
    Keywords: Agaricales/*classification/genetics/physiology ; Agaricus/classification/genetics ; Animals ; Ants/classification/*microbiology/physiology ; Biological Evolution ; *Genes, Fungal ; Molecular Sequence Data ; *Phylogeny ; RNA, Fungal/*genetics ; RNA, Ribosomal/*genetics ; RNA, Ribosomal, 16S/genetics ; Symbiosis
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  • 83
    Publication Date: 1994-12-23
    Description: The chloroplast outer envelope protein OEP86 functions as a receptor in precursor protein translocation into chloroplasts. Sequence analysis suggests that the precursor of OEP86 is directed to the chloroplast outer envelope by a cleavable, negatively charged, and unusually long amino-terminal peptide. This presequence is unlike other potential targeting signals and suggests the existence of another membrane insertion pathway. Insertion of precursor OEP86 required the hydrolysis of adenosine triphosphate and the existence of surface exposed chloroplast membrane components, and it was not competed by another precursor protein destined for the internal plastid compartments.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hirsch, S -- Muckel, E -- Heemeyer, F -- von Heijne, G -- Soll, J -- New York, N.Y. -- Science. 1994 Dec 23;266(5193):1989-92.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Botanisches Institut, Universitat Kiel, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7801125" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Amino Acid Sequence ; Chloroplast Proteins ; Chloroplasts/*metabolism ; *GTP-Binding Proteins ; Hydrogen-Ion Concentration ; Intracellular Membranes/metabolism ; Molecular Sequence Data ; Molecular Weight ; Peas ; Plant Proteins/chemistry/*metabolism ; Protein Precursors/chemistry/*metabolism ; Protein Processing, Post-Translational ; Ribulose-Bisphosphate Carboxylase/metabolism
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  • 84
    Publication Date: 1994-06-03
    Description: Multi-wavelength anomalous diffraction (MAD) has been used to determine the structure of the regulatory enzyme of de novo synthesis of purine nucleotides, glutamine 5-phosphoribosyl-1-pyrophosphate (PRPP) amidotransferase, from Bacillus subtilis. This allosteric enzyme, a 200-kilodalton tetramer, is subject to end product regulation by purine nucleotides. The metalloenzyme from B. subtilis is a paradigm for the higher eukaryotic enzymes, which have been refractory to isolation in stable form. The two folding domains of the polypeptide are correlated with functional domains for glutamine binding and for transfer of ammonia to the substrate PRPP. Eight molecules of the feedback inhibitor adenosine monophosphate (AMP) are bound to the tetrameric enzyme in two types of binding sites: the PRPP catalytic site of each subunit and an unusual regulatory site that is immediately adjacent to each active site but is between subunits. An oxygen-sensitive [4Fe-4S] cluster in each subunit is proposed to regulate protein turnover in vivo and is distant from the catalytic site. Oxygen sensitivity of the cluster is diminished by AMP, which blocks a channel through the protein to the cluster. The structure is representative of both glutamine amidotransferases and phosphoribosyltransferases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Smith, J L -- Zaluzec, E J -- Wery, J P -- Niu, L -- Switzer, R L -- Zalkin, H -- Satow, Y -- DK-42303/DK/NIDDK NIH HHS/ -- GM-24658/GM/NIGMS NIH HHS/ -- R37 DK042303/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1994 Jun 3;264(5164):1427-33.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Sciences, Purdue University, West Lafayette, IN 47907.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8197456" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Monophosphate/metabolism ; Allosteric Regulation ; Amidophosphoribosyltransferase/*chemistry/metabolism ; Amino Acid Sequence ; Animals ; Bacillus subtilis/*enzymology ; Binding Sites ; Computer Graphics ; Crystallography, X-Ray ; Humans ; Models, Molecular ; Molecular Sequence Data ; Oxygen/pharmacology ; Protein Folding ; Protein Structure, Secondary ; Saccharomyces cerevisiae
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  • 85
    Publication Date: 1994-09-16
    Description: The evolutionary origins of the protistan phylum, Myxozoa, have long been questioned. Although these obligate parasites are like protozoans in many features, several aspects of their ontogeny and morphology have implied a closer relationship to metazoan lineages. Phylogenetic analyses of 18S ribosomal RNA sequences from myxozoans and other eukaryotes, with the use of parsimony, distance, and maximum-likelihood methods, support the hypothesis that myxozoans are closely related to the bilateral animals. These results suggest that the Myxozoa, long considered an assemblage of protozoans, should be considered a metazoan phylum.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Smothers, J F -- von Dohlen, C D -- Smith, L H Jr -- Spall, R D -- New York, N.Y. -- Science. 1994 Sep 16;265(5179):1719-21.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Sciences, Idaho State University, Pocatello 83209.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8085160" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Biological Evolution ; Eukaryota/*classification/genetics ; Likelihood Functions ; Molecular Sequence Data ; Parasites/*classification/genetics ; Phylogeny ; Probability ; RNA, Protozoan/genetics ; RNA, Ribosomal, 18S/*genetics
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  • 86
    Publication Date: 1994-06-24
    Description: The structure of the leech protein decorsin, a potent 39-residue antagonist of glycoprotein IIb-IIIa and inhibitor of platelet aggregation, was determined by nuclear magnetic resonance. In contrast to other disintegrins, the Arg-Gly-Asp (RGD)-containing region of decorsin is well defined. The three-dimensional structure of decorsin is similar to that of hirudin, an anticoagulant leech protein that potently inhibits thrombin. Amino acid sequence comparisons suggest that ornatin, another glycoprotein IIb-IIIa antagonist, and antistasin, a potent Factor Xa inhibitor and anticoagulant found in leeches, share the same structural motif. Although decorsin, hirudin, and antistasin all affect the blood clotting process and appear similar in structure, their mechanisms of action and epitopes important for binding to their respective targets are distinct.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Krezel, A M -- Wagner, G -- Seymour-Ulmer, J -- Lazarus, R A -- New York, N.Y. -- Science. 1994 Jun 24;264(5167):1944-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8009227" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Hirudins/chemistry ; Invertebrate Hormones/chemistry ; *Leeches ; Magnetic Resonance Spectroscopy ; Molecular Sequence Data ; Oligopeptides/chemistry ; Platelet Membrane Glycoproteins/*antagonists & inhibitors ; Protein Conformation ; Protein Structure, Secondary ; Proteins/*chemistry
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  • 87
    Publication Date: 1994-04-01
    Description: Fetal cardiomyocytes isolated from transgenic mice carrying a fusion gene of the alpha-cardiac myosin heavy chain promoter with a beta-galactosidase reporter were examined for their ability to form stable intracardiac grafts. Embryonic day 15 transgenic cardiomyocytes delivered directly into the myocardium of syngeneic hosts formed stable grafts, as identified by nuclear beta-galactosidase activity. Grafted cardiomyocytes were observed as long as 2 months after implantation, the latest date assayed. Intracardiac graft formation did not induce overtly negative effects on the host myocardium and was not associated with chronic immune rejection. Electron microscopy revealed the presence of nascent intercalated disks connecting the engrafted fetal cardiomyocytes and the host myocardium. These results suggest that intracardiac grafting might provide a useful approach for myocardial repair, provided that the grafted cells can contribute to myocardial function.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Soonpaa, M H -- Koh, G Y -- Klug, M G -- Field, L J -- HL45453/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1994 Apr 1;264(5155):98-101.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis 46202-4800.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8140423" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Cell Communication ; Cell Differentiation ; Cell Nucleus/metabolism ; *Cell Transplantation ; DNA/biosynthesis ; DNA Primers ; Electrocardiography ; Fetal Heart/*cytology ; *Fetal Tissue Transplantation ; Gap Junctions/physiology/ultrastructure ; Genetic Markers ; Heart/physiology ; Intercellular Junctions/physiology/*ultrastructure ; Mice ; Mice, Transgenic ; Molecular Sequence Data ; Myocardium/*cytology/ultrastructure ; beta-Galactosidase/analysis
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  • 88
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-06-24
    Description: The basic notions of transition state theory have been exploited in the past to generate highly selective catalysts from the vast library of antibody molecules in the immune system. These same ideas were used to isolate an RNA molecule, from a large library of RNAs, that catalyzes the isomerization of a bridged biphenyl. The RNA-catalyzed reaction displays Michaelis-Menten kinetics with a catalytic rate constant (kcat) of 2.8 x 10(-5) per minute and a Michaelis constant (Km) of 542 microM; the reaction is competitively inhibited by the planar transition state analog with an inhibition constant (Ki) value of approximately 7 microM. This approach may provide a general strategy for expanding the scope of RNA catalysis beyond those reactions in which the substrates are nucleic acids or nucleic acid derivatives.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Prudent, J R -- Uno, T -- Schultz, P G -- GM08352A/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1994 Jun 24;264(5167):1924-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry, University of California, Berkeley.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8009223" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; Biphenyl Compounds/chemistry/metabolism ; Catalysis ; Kinetics ; Molecular Sequence Data ; Nucleic Acid Conformation ; Nucleic Acid Denaturation ; Polymerase Chain Reaction ; RNA, Catalytic/chemistry/*metabolism ; Stereoisomerism ; Temperature
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  • 89
    Publication Date: 1994-07-15
    Description: A subset of patients who have undergone coronary angioplasty develop restenosis, a vessel renarrowing characterized by excessive proliferation of smooth muscle cells (SMCs). Of 60 human restenosis lesions examined, 23 (38 percent) were found to have accumulated high amounts of the tumor suppressor protein p53, and this correlated with the presence of human cytomegalovirus (HCMV) in the lesions. SMCs grown from the lesions expressed HCMV protein IE84 and high amounts of p53. HCMV infection of cultured SMCs enhanced p53 accumulation, which correlated temporally with IE84 expression. IE84 also bound to p53 and abolished its ability to transcriptionally activate a reporter gene. Thus, HCMV, and IE84-mediated inhibition of p53 function, may contribute to the development of restenosis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Speir, E -- Modali, R -- Huang, E S -- Leon, M B -- Shawl, F -- Finkel, T -- Epstein, S E -- New York, N.Y. -- Science. 1994 Jul 15;265(5170):391-4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Cardiology Branch, National Institutes of Health, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8023160" target="_blank"〉PubMed〈/a〉
    Keywords: Adolescent ; Adult ; Aged ; Aged, 80 and over ; *Angioplasty, Balloon ; Antigens, Viral/*metabolism ; Atherectomy, Coronary ; Base Sequence ; Cells, Cultured ; Coronary Disease/*etiology/pathology/therapy ; Coronary Vessels/cytology/metabolism/microbiology ; Cytomegalovirus/*physiology ; Genes, p53 ; Humans ; Immediate-Early Proteins/*metabolism ; Middle Aged ; Molecular Sequence Data ; Muscle, Smooth, Vascular/cytology/metabolism/microbiology ; Recurrence ; Transcriptional Activation ; Transfection ; Tumor Suppressor Protein p53/genetics/*metabolism
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  • 90
    Publication Date: 1994-09-30
    Description: The RAD1 and RAD10 genes of Saccharomyces cerevisiae are required for both nucleotide excision repair and certain mitotic recombination events. Here, model recombination and repair intermediates were used to show that Rad1-Rad10-mediated cleavage occurs at duplex-single-strand junctions. Moreover, cleavage occurs only on the strand containing the 3' single-stranded tail. Thus, both biochemical and genetic evidence indicate a role for the Rad1-Rad10 complex in the cleavage of specific recombination intermediates. Furthermore, these data suggest that Rad1-Rad10 endonuclease incises DNA 5' to damaged bases during nucleotide excision repair.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bardwell, A J -- Bardwell, L -- Tomkinson, A E -- Friedberg, E C -- CA12428/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1994 Sep 30;265(5181):2082-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Pathology, University of Texas Southwestern Medical Center at Dallas 75235.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8091230" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; *DNA Repair ; DNA Repair Enzymes ; DNA, Fungal/genetics/*metabolism ; DNA, Single-Stranded/metabolism ; *DNA-Binding Proteins ; Endodeoxyribonucleases/*metabolism ; *Endonucleases ; Fungal Proteins/*metabolism ; Molecular Sequence Data ; Oligodeoxyribonucleotides/metabolism ; *Recombination, Genetic ; Saccharomyces cerevisiae/*genetics/metabolism ; *Saccharomyces cerevisiae Proteins ; Single-Strand Specific DNA and RNA Endonucleases
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  • 91
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-03-11
    Description: Protein tyrosine phosphatases (PTPs) constitute a family of receptor-like and cytoplasmic signal transducing enzymes that catalyze the dephosphorylation of phosphotyrosine residues and are characterized by homologous catalytic domains. The crystal structure of a representative member of this family, the 37-kilodalton form (residues 1 to 321) of PTP1B, has been determined at 2.8 A resolution. The enzyme consists of a single domain with the catalytic site located at the base of a shallow cleft. The phosphate recognition site is created from a loop that is located at the amino-terminus of an alpha helix. This site is formed from an 11-residue sequence motif that is diagnostic of PTPs and the dual specificity phosphatases, and that contains the catalytically essential cysteine and arginine residues. The position of the invariant cysteine residue within the phosphate binding site is consistent with its role as a nucleophile in the catalytic reaction. The structure of PTP1B should serve as a model for other members of the PTP family and as a framework for understanding the mechanism of tyrosine dephosphorylation.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barford, D -- Flint, A J -- Tonks, N K -- CA53840/CA/NCI NIH HHS/ -- New York, N.Y. -- Science. 1994 Mar 11;263(5152):1397-404.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉W.M. Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, NY 11724.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8128219" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Binding Sites ; Computer Graphics ; Crystallography, X-Ray ; Humans ; Models, Molecular ; Molecular Sequence Data ; Phosphates/metabolism ; Protein Conformation ; Protein Folding ; Protein Structure, Secondary ; Protein Tyrosine Phosphatases/*chemistry/isolation & purification/metabolism ; Substrate Specificity ; Tungsten Compounds/metabolism
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  • 92
    Publication Date: 1994-09-16
    Description: To identify proteins that may participate in the activation of the protein kinase Raf, proteins that interact with Raf were selected in a two-hybrid screen. Two members of the 14-3-3 protein family were isolated that interacted with both the amino terminal regulatory regions of Raf and the kinase domain of Raf, but did not compete with the guanine nucleotide-binding protein Ras for binding to Raf. 14-3-3 proteins associated with Raf in mammalian cells and accompanied Raf to the membrane in the presence of activated Ras. In yeast cells expressing Raf and MEK, mammalian 14-3-3 beta or 14-3-3 zeta activated Raf to a similar extent as did expression of Ras. Therefore, 14-3-3 proteins may participate in or be required for the regulation of Raf function. These findings suggest a role for 14-3-3 proteins in Raf-mediated signal transduction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Freed, E -- Symons, M -- Macdonald, S G -- McCormick, F -- Ruggieri, R -- New York, N.Y. -- Science. 1994 Sep 16;265(5179):1713-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Onyx Pharmaceuticals, Richmond, CA 94806-5206.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8085158" target="_blank"〉PubMed〈/a〉
    Keywords: 14-3-3 Proteins ; Amino Acid Sequence ; Animals ; Cell Line ; Cell Membrane/enzymology ; Cytosol/enzymology ; Enzyme Activation ; GTP-Binding Proteins/metabolism ; HeLa Cells ; Humans ; MAP Kinase Kinase 1 ; *Mitogen-Activated Protein Kinase Kinases ; Molecular Sequence Data ; Nerve Tissue Proteins/*metabolism ; Protein-Serine-Threonine Kinases/chemistry/genetics/*metabolism ; Protein-Tyrosine Kinases/genetics/metabolism ; Proto-Oncogene Proteins/chemistry/*metabolism ; Proto-Oncogene Proteins c-raf ; Recombinant Proteins/metabolism ; Saccharomyces cerevisiae/genetics/growth & development ; Signal Transduction ; *Tyrosine 3-Monooxygenase ; Zinc Fingers
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  • 93
    Publication Date: 1994-04-29
    Description: A gene, reaper (rpr), that appears to play a central control function for the initiation of programmed cell death (apoptosis) in Drosophila was identified. Virtually all programmed cell death that normally occurs during Drosophila embryogenesis was blocked in embryos homozygous for a small deletion that includes the reaper gene. Mutant embryos contained many extra cells and failed to hatch, but many other aspects of development appeared quite normal. Deletions that include reaper also protected embryos from apoptosis caused by x-irradiation and developmental defects. However, high doses of x-rays induced some apoptosis in mutant embryos, and the resulting corpses were phagocytosed by macrophages. These data suggest that the basic cell death program is intact although it was not activated in mutant embryos. The DNA encompassed by the deletion was cloned and the reaper gene was identified on the basis of the ability of cloned DNA to restore apoptosis to cell death defective embryos in germ line transformation experiments. The reaper gene appears to encode a small peptide that shows no homology to known proteins, and reaper messenger RNA is expressed in cells destined to undergo apoptosis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉White, K -- Grether, M E -- Abrams, J M -- Young, L -- Farrell, K -- Steller, H -- 5 F32 NS08536/NS/NINDS NIH HHS/ -- New York, N.Y. -- Science. 1994 Apr 29;264(5159):677-83.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Brain and Cognitive Sciences, Cambridge, MA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8171319" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Apoptosis/*genetics ; Base Sequence ; Cloning, Molecular ; DNA Primers ; Drosophila/cytology/embryology/*genetics ; *Drosophila Proteins ; Embryo, Nonmammalian/cytology ; *Genes, Insect ; Models, Genetic ; Molecular Sequence Data ; Mutation ; Nervous System/cytology ; Neurons/cytology ; Peptides/chemistry/*genetics/physiology
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  • 94
    Publication Date: 1994-10-21
    Description: RNA polymerases I, II, and III each use the TATA-binding protein (TBP). Regulators that target this shared factor may therefore provide a means to coordinate the activities of the three nuclear RNA polymerases. The repressor Dr1 binds to TBP and blocks the interaction of TBP with polymerase II- and polymerase III-specific factors. This enables Dr1 to coordinately regulate transcription by RNA polymerases II and III. Under the same conditions, Dr1 does not inhibit polymerase I transcription. By selectively repressing polymerases II and III, Dr1 may shift the physiological balance of transcriptional output in favor of polymerase I.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉White, R J -- Khoo, B C -- Inostroza, J A -- Reinberg, D -- Jackson, S P -- Wellcome Trust/United Kingdom -- New York, N.Y. -- Science. 1994 Oct 21;266(5184):448-50.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Wellcome/CRC Institute, University of Cambridge, UK.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7939686" target="_blank"〉PubMed〈/a〉
    Keywords: Base Sequence ; DNA-Binding Proteins/metabolism ; HeLa Cells ; Humans ; Molecular Sequence Data ; Phosphoproteins/metabolism/*pharmacology ; RNA Polymerase I/*metabolism ; RNA Polymerase II/*metabolism ; RNA Polymerase III/*metabolism ; Saccharomyces cerevisiae Proteins ; TATA Box ; TATA-Binding Protein Associated Factors ; TATA-Box Binding Protein ; Transcription Factor TFIIB ; Transcription Factor TFIIIB ; Transcription Factors/metabolism/*pharmacology ; *Transcription Factors, TFIII ; Transcription, Genetic/*drug effects
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  • 95
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-04-22
    Description: A cytoplasmically inherited element, [URE3], allows yeast to use ureidosuccinate in the presence of ammonium ion. Chromosomal mutations in the URE2 gene produce the same phenotype. [URE3] depends for its propagation on the URE2 product (Ure2p), a negative regulator of enzymes of nitrogen metabolism. Saccharomyces cerevisiae strains cured of [URE3] with guanidium chloride were shown to return to the [URE3]-carrying state without its introduction from other cells. Overproduction of Ure2p increased the frequency with which a strain became [URE3] by 100-fold. In analogy to mammalian prions, [URE3] may be an altered form of Ure2p that is inactive for its normal function but can convert normal Ure2p to the altered form. The genetic evidence presented here suggests that protein-based inheritance, involving a protein unrelated to the mammalian prion protein, can occur in a microorganism.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wickner, R B -- New York, N.Y. -- Science. 1994 Apr 22;264(5158):566-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Section on Genetics of Simple Eukaryotes, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7909170" target="_blank"〉PubMed〈/a〉
    Keywords: Aspartic Acid/analogs & derivatives/metabolism ; Base Sequence ; Crosses, Genetic ; Fungal Proteins/chemistry/*genetics/metabolism ; Genes, Dominant ; Genes, Fungal ; Genes, Recessive ; Glutathione Peroxidase ; Guanidine ; Guanidines/pharmacology ; Molecular Sequence Data ; Mutation ; Phenotype ; Plasmids ; PrPSc Proteins ; Prions/chemistry/genetics/metabolism ; Saccharomyces cerevisiae/*genetics/metabolism ; *Saccharomyces cerevisiae Proteins
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  • 96
    Publication Date: 1994-10-07
    Description: Loss of heterozygosity data from familial tumors suggest that BRCA1, a gene that confers susceptibility to ovarian and early-onset breast cancer, encodes a tumor suppressor. The BRCA1 region is also subject to allelic loss in sporadic breast and ovarian cancers, an indication that BRCA1 mutations may occur somatically in these tumors. The BRCA1 coding region was examined for mutations in primary breast and ovarian tumors that show allele loss at the BRCA1 locus. Mutations were detected in 3 of 32 breast and 1 of 12 ovarian carcinomas; all four mutations were germline alterations and occurred in early-onset cancers. These results suggest that mutation of BRCA1 may not be critical in the development of the majority of breast and ovarian cancers that arise in the absence of a mutant germline allele.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Futreal, P A -- Liu, Q -- Shattuck-Eidens, D -- Cochran, C -- Harshman, K -- Tavtigian, S -- Bennett, L M -- Haugen-Strano, A -- Swensen, J -- Miki, Y -- CA48711/CA/NCI NIH HHS/ -- CA55914/CA/NCI NIH HHS/ -- CA56749/CA/NCI NIH HHS/ -- etc. -- New York, N.Y. -- Science. 1994 Oct 7;266(5182):120-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7939630" target="_blank"〉PubMed〈/a〉
    Keywords: Adult ; Age of Onset ; Alleles ; BRCA1 Protein ; Base Sequence ; Breast Neoplasms/*genetics ; Chromosomes, Human, Pair 17 ; Female ; *Genes, Tumor Suppressor ; Genetic Predisposition to Disease ; *Germ-Line Mutation ; Heterozygote ; Humans ; Middle Aged ; Molecular Sequence Data ; Neoplasm Proteins/*genetics ; Ovarian Neoplasms/*genetics ; Transcription Factors/*genetics
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  • 97
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-01-07
    Description: Heterotrimeric guanosine triphosphate (GTP)-binding proteins (G proteins) may participate in membrane traffic events. A complementary DNA (cDNA) was isolated from a mouse pituitary cDNA library that corresponded to an alternatively spliced form of the gene encoding the G protein alpha subunit G alpha i2. The cDNA was identical to that encoding G alpha i2 except that the region encoding for the carboxyl-terminal 24 amino acids was replaced by a longer region encoding 35 amino acids that have no sequence similarity with G alpha i2 or other members of the G protein family. This alternative spliced product and the corresponding protein (sGi2) were present in several tissues. Specific antibodies revealed that sGi2 was localized in the Golgi apparatus, suggesting a role in membrane transport. Thus, alternative splicing may generate from a single gene two G protein alpha subunits with differential cellular localization and function.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Montmayeur, J P -- Borrelli, E -- New York, N.Y. -- Science. 1994 Jan 7;263(5143):95-8.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratoire de Genetique Moleculaire des Eucaryotes, CNRS, INSERM U184, Faculte de Medecine, Strasbourg, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8272874" target="_blank"〉PubMed〈/a〉
    Keywords: *Alternative Splicing ; Amino Acid Sequence ; Animals ; Base Sequence ; Cell Line ; Cell Membrane/metabolism ; Coatomer Protein ; DNA, Complementary/genetics ; GTP-Binding Protein alpha Subunit, Gi2 ; *GTP-Binding Protein alpha Subunits, Gi-Go ; GTP-Binding Proteins/analysis/chemistry/genetics/*metabolism ; Golgi Apparatus/chemistry/*metabolism ; Mice ; Microtubule-Associated Proteins/analysis ; Molecular Sequence Data ; Oncogene Proteins/analysis/chemistry/genetics/*metabolism ; *Proto-Oncogene Proteins
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  • 98
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-05-20
    Description: The biological role of RNA is delimited by its possible reactions, which can be explored by selection. A comparison of selected RNAs that bind one ligand with those that bind two related ligands suggests that a single nucleotide substitution can expand binding specificity. An RNA site with dual (joint) specificity has adenine and cytosine bases whose pKa's appear shifted upward, thereby mimicking an efficient general acid-base catalyst. The joint site also contains two conserved, looped arginine-coding triplets implicated in arginine site formation. Two selected joint RNAs are identical in some regions and distinct in others. The distinct regions, like some peptides, seem to function similarly without being similar in primary structure.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Connell, G J -- Yarus, M -- New York, N.Y. -- Science. 1994 May 20;264(5162):1137-41.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder 80309-0347.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7513905" target="_blank"〉PubMed〈/a〉
    Keywords: Arginine/*metabolism ; Base Sequence ; Binding Sites ; Chromatography, Affinity ; Consensus Sequence ; Guanosine/*metabolism ; Hydrogen-Ion Concentration ; Molecular Sequence Data ; Nucleic Acid Conformation ; RNA/chemistry/*metabolism ; RNA, Catalytic/chemistry/metabolism
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  • 99
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    Unknown
    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-11-18
    Description: DNA was extracted from 80-million-year-old bone fragments found in strata of the Upper Cretaceous Blackhawk Formation in the roof of an underground coal mine in eastern Utah. This DNA was used as the template in a polymerase chain reaction that amplified and sequenced a portion of the gene encoding mitochondrial cytochrome b. These sequences differ from all other cytochrome b sequences investigated, including those in the GenBank and European Molecular Biology Laboratory databases. DNA isolated from these bone fragments and the resulting gene sequences demonstrate that small fragments of DNA may survive in bone for millions of years.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Woodward, S R -- Weyand, N J -- Bunnell, M -- New York, N.Y. -- Science. 1994 Nov 18;266(5188):1229-32.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology, Brigham Young University, Provo, UT 84602.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7973705" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Bone and Bones/*chemistry ; Consensus Sequence ; Cytochrome b Group/*genetics ; DNA, Mitochondrial/chemistry/*genetics/isolation & purification ; Databases, Factual ; History, Ancient ; Molecular Sequence Data ; *Paleontology ; Polymerase Chain Reaction ; Sequence Analysis, DNA ; Sequence Homology, Nucleic Acid ; Utah
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  • 100
    Publication Date: 1994-03-25
    Description: The Drosophila decapentaplegic (dpp) gene encodes a transforming growth factor-beta (TGF-beta)-like protein that plays a key role in several aspects of development. Transduction of the DPP signal was investigated by cloning of serine-threonine kinase transmembrane receptors from Drosophila because this type of receptor is specific for the TGF-beta-like ligands. Here evidence is provided demonstrating that the Drosophila saxophone (sax) gene, a previously identified female sterile locus, encodes a TGF-beta-like type I receptor. Embryos from sax mothers and dpp embryos exhibit similar mutant phenotypes during early gastrulation, and these two loci exhibit genetic interactions, which suggest that they are utilized in the same pathway. These data suggest that sax encodes a receptor for dpp.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Xie, T -- Finelli, A L -- Padgett, R W -- New York, N.Y. -- Science. 1994 Mar 25;263(5154):1756-9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Waksman Institute, Rutgers University, Piscataway, NJ 08855-0759.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8134837" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; Base Sequence ; Cloning, Molecular ; Drosophila/embryology/*genetics/metabolism ; *Drosophila Proteins ; Embryo, Nonmammalian/metabolism ; Female ; *Genes, Insect ; Insect Hormones/genetics/*metabolism ; Male ; Molecular Sequence Data ; Mutation ; Protein-Serine-Threonine Kinases/chemistry/*genetics/metabolism ; Receptors, Transforming Growth Factor beta/chemistry/*genetics/metabolism ; Signal Transduction ; Transforming Growth Factor beta/genetics/*metabolism
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    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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