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  • Cell & Developmental Biology  (5)
  • Atomic and molecular structure and dynamics  (3)
  • Lolium multiflorum  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Transgenic Italian ryegrass (Lolium multiflorum) plants from microprojectile bombardment of embryogenic suspension cells (1997)
    Springer
    Plant cell reports 16 (1997), S. 379-384 
    Details
    ISSN: 1432-203X
    Keywords: Key words Forage and turf grasses ; Italian ryegrass ; Lolium multiflorum ; Microprojectile bombardment ; Transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenic forage-type Italian ryegrass (Lolium multiflorum Lam.) plants have been obtained by microprojectile bombardment of embryogenic suspension cells using a chimeric hygromycin phosphotransferase (hph) gene construct driven by rice Act1 5′ regulatory sequences. Parameters for the bombardment of embryogenic suspension cultures with the particle inflow gun were partially optimized using transient expression assays of a chimeric β-glucuronidase (gusA) gene driven by the maize Ubi1 promoter. Stably transformed clones were recovered with a selection scheme using hygromycin in liquid medium followed by a plate selection. Plants were regenerated from 33% of the hygromycin-resistant calli. The transgenic nature of the regenerated plants was demonstrated by Southern hybridization analysis. Expression of the transgene in transformed adult Italian ryegrass plants was confirmed by northern analysis and a hygromycin phosphotransferase enzyme assay.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01146777
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  • 2
    Electronic Resource
    Electronic Resource
    Asymmetric somatic hybridization between tall fescue (Festuca arundinacea Schreb.) and irradiated Italian ryegrass (Lolium multiflorum Lam.) protoplasts (1994)
    Springer
    Theoretical and applied genetics 88 (1994), S. 509-519 
    Details
    ISSN: 1432-2242
    Keywords: Asymmetric somatic hybrids ; forage grasses: fescues and ryegrasses ; Plastome-genome interaction ; Festuca arundinacea ; Lolium multiflorum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Intergeneric asymmetric somatic hybrids have been obtained by the fusion of metabolically inactivated protoplasts from embryogenic suspension cultures ofFestuca arundinacea (recipient) and protoplasts from a non-morphogenic cell suspension ofLolium multiflorum (donor) irradiated with 10, 25, 50, 100, 250 and 500 Gy of X-rays. Regenerating calli led to the recovery of genotypically and phenotypically different asymmetric somatic hybridFestulolium plants. The genome composition of the asymmetric somatic hybrid clones was characterized by quantitative dot-blot hybridizations using dispersed repetitive DNA sequences specific to tall fescue and Italian ryegrass. Data from dot-blot hybridizations using two cloned Italian ryegrass-specific sequences as probes showed that irradiation favoured a unidirectional elimination of most or part of the donor chromosomes in asymmetric somatic hybrid clones obtained from fusion experiments using donor protoplasts irradiated at doses ≤ 250 Gy. Irradiation of cells of the donor parent with 500 Gy prior to protoplast fusion produced highly asymmetric nuclear hybrids with over 80% elimination of the donor genome as well as clones showing a complete loss of donor chromosomes. Further information on the degree of asymmetry in regenerated hybrid plants was obtained from chromosomal analysis including in situ hybridizations withL. multiflorum-specific repetitive sequences. A Southern blot hybridization analysis using one chloroplast and six mitochondrial-specific probes revealed preferentially recipient-type organelles in asymmetric somatic hybrid clones obtained from fusion experiments with donor protoplasts irradiated with doses higher than 100 Gy. It is concluded that the irradiation of donor cells before fusion at different doses can be used for producing both nuclear hybrids with limited donor DNA elimination or highly asymmetric nuclear hybrid plants in an intergeneric graminaceous combination. For a wide range of radiation doses tested (25–250Gy), the degree of the species-specific genome elimination from the irradiated partner seems not to be dose dependent. A bias towards recipient-type organelles was apparent when extensive donor nuclear genome elimination occurred.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01240911
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  • 3
    Electronic Resource
    Electronic Resource
    Intergeneric symmetric and asymmetric somatic hybridization in Festuca and Lolium (1955)
    Springer
    Euphytica 85 (1955), S. 235-245 
    Details
    ISSN: 1573-5060
    Keywords: intergeneric somatic hybrids ; forage grasses ; fescue ; Festuca arundinacea ; F. rubra ; ryegrasses ; Lolium multiflorum ; L. perenne ; Alopecurus pratensis ; species-specific repetitive DNA sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Intergeneric symmetric and asymmetric somatic hybrids have been obtained by fusion of metabolically inactivated protoplasts from embryogenic suspension cultures of tall fescue (Festuca arundinacea Schreb.) and unirradiated or 10–500 Gy-irradiated protoplasts from non-morphogenic cell suspensions of Italian ryegrass (Lolium multiflorum Lam.). Genotypically and phenotypically different somatic hybrid Festulolium mature flowering plants were regenerated. Species-specific sequences from F. arundinacea and L. multiflorum being dispersed and evenly-represented in the corresponding genomes were isolated and used for the molecular characterization of the nuclear make-up of the intergeneric, somatic Festulolium plants recovered. The irradiation of Italian ryegrass protoplasts with ≤250 Gy X-rays prior to fusogenic treatment favoured the unidirectional elimination of most or part of the donor chromosomes. Irradiation of L. multiflorum protoplasts with 500 Gy produced highly asymmetric (over 80% donor genome elimination) nuclear hybrids and clones showing a complete loss of donor chromosomes. The RFLP analysis of the organellar composition in symmetric and asymmetric tall fescue (+) Italian ryegrass regenerants confirmed their somatic hybrid character and revealed a bias towards recipient-type organelles when extensive donor nuclear genome elimination had occurred. Approaches aimed at improving persistence of ryegrasses based on asymmetric somatic hybridization with largely sexually-incompatible grass species (F. rubra and Alopecurus pratensis), and at transferring the cytoplasmic male sterility trait by intra- and inter-specific hybridization in L. multiflorum and L. perenne, have been undertaken.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00023952
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  • 4
    Electronic Resource
    Electronic Resource
    Reflection electron energy-loss spectroscopy and imaging for surface studies in transmission electron microscopes (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 20 (1992), S. 390-405 
    Details
    ISSN: 1059-910X
    Keywords: Reflection electron microscopy ; Secondary electron imaging ; Field emission gun ; In situ REM ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A review is given on the techniques and applications of high-energy reflection electron energy-loss spectroscopy (REELS) and reflection electron microscopy (REM) for surface studies in scanning transmission electron microscopes (STEM) and conventional transmission electron microscopes (TEM). A diffraction method is introduced to identify a surface orientation in the geometry of REM. The surface dielectric response theory is presented and applied for studying α-alumina surfaces. Domains of the α-alumina (012) surface initially terminated with oxygen can be reduced by an intense electron beam to produce Al metal; the resistance to beam damage of surface domains initially terminated with Al+3 ions is attributed to the screening effect of adsorbed oxygen. Surface energy-loss near-edge structure (ELNES), extended energy-loss fine structure (EXELFS), and microanalysis using REELS are illustrated based on the studies of TiO2 and MgO. Effects of surface resonances (or channeling) on the REELS signal-to-background ratio are described. The REELS detection of a monolayer of oxygen adsorption on diamond (111) surfaces is reported.It is shown that phase contrast REM image content can be significantly increased with the use of a field emission gun (FEG). Phase contrast effects close to the core of a screw dislocation are discussed and the associated Fresnel fringes around a surface step are observed. Finally, an in situ REM experiment is described for studying atomic desorption and diffusion processes on α-alumina surfaces at temperatures of 1,300 - 1,400°C.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070200409
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  • 5
    Electronic Resource
    Electronic Resource
    Experimental conditions for surface microanalysis with reflection electron energy-loss spectroscopy (1989)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 11 (1989), S. 70-75 
    Details
    ISSN: 0741-0581
    Keywords: REELS ; REM ; Surface plasmon ; Signal-to-background ratio ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Experimental conditions for obtaining the optimum signal-to-background (S/B) ratio in reflection electron energy-loss spectroscopy (REELS) are investigated. It is shown that the S/ B ratio can be improved by lowering the incident energy of the electrons. The spectra taken from the GaAs (660) specular reflection spot under the surface resonance condition is demonstrated to have the best S/B ratio and lowest surface plasma excitation, which is capable of providing structural information on the top few atomic layers.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060110109
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  • 6
    Electronic Resource
    Electronic Resource
    Reflection high resolution analytical electron microscopy: A technique for studying crystal surfaces (1988)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 10 (1988), S. 35-43 
    Details
    ISSN: 0741-0581
    Keywords: REM ; RHEED ; TRHEED ; REELS ; EDX ; RHEED theory ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Reflection electron microscopy (REM), reflection high energy electron diffraction (RHEED), reflection electron energy-loss spectroscopy (REELS), and energy dispersion x-ray spectroscopy (EDX) have been comprehensively used as a technique, termed reflection high resolution analytical electron microscopy (RHRAEM), for studying the structures of the bulk crystal GaAs (110) surfaces by transmission electron microscopy (TEM). The simultaneous observations of surface topography imaging, the surface diffraction mechanism with RHEED, surface atomic inner-shell excitations with REELS, and surface chemical compositions with EDX provide a systematic description of the atomic structure and chemical structure of the surface. The surface channelling effect has been observed in GaAs (110) with REELS, which may provide a basis for localizing surface foreign atoms with ALCHEMI. The theoretically predicted surface-resonance wave has been observed directly in the RHEED pattern; the surface-captured Bragg reflection wave have been identified. It is shown that surface chemical compositions can be determined by analyzing the EDX spectra obtained in the REM case. Finally, the surface monolayer resonance characteristic of the RHRAEM has been confirmed by calculations with dynamical RHEED theory.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060100106
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  • 7
    Electronic Resource
    Electronic Resource
    Imaging friction tracks at diamond surfaces using reflection electron microscopy (1991)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 17 (1991), S. 231-240 
    Details
    ISSN: 0741-0581
    Keywords: Plastic deformation ; Adhesion friction ; Local contacting pressure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Reflection electron microscopy (REM) is applied to image the structure of polished natural diamond (001) surfaces (of 5 × 4 mm size) after friction experiments under a pressure below the critical value. Friction tracks marked by a diamond needle after a single pass movement under a pressure of 13 GPa can be seen in REM images and show non-uniform contrast. The surface shows relatively dark image contrast at the light contacted area, which is possibly due to the structural modification at the top atomic layer. The high local contacting pressure pushes part of the needle into the surface which causes fracture, resulting in the formation of grooves at the surface. It is possible to have plastic deformation in this process, but no evidence has been found for the presence of cracking. The observations support the adhesion frictional mechanism rather than the micro-cleavage model.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060170210
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  • 8
    Electronic Resource
    Electronic Resource
    Surface microanalysis by reflection electron energy-loss spectroscopy (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 14 (1990), S. 13-20 
    Details
    ISSN: 0741-0581
    Keywords: ω correction ; Lorentzian angular distribution ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Several basic physical concepts of applying eq. Ik = IσNxt to surface microanalysis by reflection electron energy-loss spectroscopy (REELS) are clarified. Here Ik and I are the integrated intensities of the core ionization edge and the low loss part, σ is the scattering cross section of element x with atomic concentration Nx, and t is the specimen thickness. The reflected inelastic electrons are found to be distributed almost symmetrically around the Bragg sports and can be reasonably described by a Lorentzian function. EELS microanalysis can be performed by using the diffracted sports. The ω correction, arising from the angular contributions of the neighbouring spots into the spectrometer collecting aperture, is required to be considered.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060140104
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  • 9
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    Variational energies and the Fermi contact term for the low-lying states of lithium: Basis-set completeness (2012)
    American Physical Society (APS)
    Details
    Publication Date: 2012-05-25
    Description: Author(s): L. M. Wang, Z.-C. Yan, H. X. Qiao, and G. W. F. Drake Nonrelativistic energies for the low-lying states of lithium are calculated using the variational method in Hylleraas coordinates. Variational eigenvalues for the infinite nuclear mass case with up to 34 020 terms are −7.478 060 323 910 147(1) a.u. for 1 s 2 2 s   2   S , −7.354 098 421 444 37(1) a.u. for 1 s ... [Phys. Rev. A 85, 052513] Published Thu May 24, 2012
    Keywords: Atomic and molecular structure and dynamics
    Print ISSN: 1050-2947
    Electronic ISSN: 1094-1622
    Topics: Physics
    Published by American Physical Society (APS)
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  • 10
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    Bound-state energies of lithium in magnetic fields using Hylleraas basis functions (2013)
    American Physical Society (APS)
    Details
    Publication Date: 2013-04-30
    Description: Author(s): Yin Tang, Liming Wang, Xuanyu Song, Xiaofeng Wang, Z.-C. Yan, and Haoxue Qiao The variational method in Hylleraas coordinates is applied to calculate the 1 s 2 2 s 0 , 1 s 2 2 p −1 , and 1 s 2 3 d −2 states of the lithium atom in magnetic fields with field strength up to 2×10 9 G. The computational method is based on multiple basis sets that are optimized for all nonlinear parameters for a giv... [Phys. Rev. A 87, 042518] Published Mon Apr 29, 2013
    Keywords: Atomic and molecular structure and dynamics
    Print ISSN: 1050-2947
    Electronic ISSN: 1094-1622
    Topics: Physics
    Published by American Physical Society (APS)
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