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  • Electronic Resource  (4)
  • Engineering  (2)
  • Microspore protoplasts  (2)
  • 1
    ISSN: 1432-2242
    Keywords: Microspore protoplasts ; Somatic protoplasts ; Fusions ; Triploids ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Microspore protoplasts (n) isolated at the tetrad stage from plants of Nicotiana tabacum Km+ (2n=4x=48) were fused with somatic cell protoplasts (2n) of WT N. rustica (2n=4x=48) to produce triploid plants. A total of 21.2×106 microspore protoplasts were fused with 11.2×106 somatic cell protoplasts using the high pH/Ca+ + method. Microspore protoplasts did not divide and WT N. rustica protoplasts stopped dividing when the protoplast-derived colonies were transferred to a selection medium containing kanamycin. A total of 104 actively growing green colonies were recovered on the selection medium. Ninety-six of these colonies were tested for their hybrid nature by PAGE of peroxidases and were found to contain bands characteristic of both parents. Hybrid nature of the plants regenerated from some of the selected colonies was confirmed by IEF of leaf esterases, by NPT II activity assay and by hybridizing total DNAs restricted with EcoR I to a cloned 18s rDNA fragment. Root tip squashes of six of the hybrid plants revealed chromosome numbers ranging from 58–72. From chromosomal and biochemical analysis, it can be concluded that the procedure of fusing microspore protoplasts (n) of species A carrying a dominant selection marker with WT somatic cell protoplasts (2n) of species B can be a convenient selection method for the synthesis of triploid plants. The significance of triploids lies in their subsequent use for transferring alien chromosomes and genes of species A to species B.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 78 (1989), S. 547-552 
    ISSN: 1432-2242
    Keywords: Microspore protoplasts ; Protoplast fusion ; Gametosomatic hybrids ; Organelle transmission ; Nicotiana species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Gametosomatic hybrids produced by the fusion of microspore protoplasts of Nicotiana tabacum Km+Sr+ with somatic cell protoplasts of N. rustica were analysed for their organelle composition. For the analysis of mitochondrial (mt)DNA, species-specific patterns were generated by Southern hybridization of restriction endonuclease digests of total DNA and mtDNA with four DNA probes of mitochondrial origin: cytochrome oxidase subunit I, cytochrome oxidase subunit II, 26s rDNA and 5s-18s rDNA. Of the 22 hybrids analyzed, some had parental-type pattern for some probes and novel-type for the others, indicating interaction between mtDNA of the two parent species. For chloroplast (cp)DNA analysis, species-specific patterns were generated by Southern hybridization of restriction endonuclease digests of total DNA with large subunits of ribulose bisphosphate carboxylase and cpDNA as probes. All the hybrids had N. rustica-specific patterns. Hybrids were not resistant to streptomycin, a trait encoded by the chloroplast genome of N. tabacum. In gametosomatic fusions of the two Nicotiana species, mitochondria but not the chloroplasts are transmitted from the parent contributing microspore protoplasts.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 14 (1992), S. 1473-1484 
    ISSN: 0271-2091
    Keywords: Bluff body ; Wake ; Vortex shedding ; Unsteady periodic flow ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The structure of confined wakes behind a square cylinder in a channel is investigated via the numerical solution of the unsteady Navier-Stokes equations. Vortex shedding behind the cylinder induces periodicity in the flow field. Details of the phenomenon are simulated through numerical flow visualization. The unsteady periodic wake can be characterized by the Strouhal number, which varies with the Reynolds number and the blockage ratio of the channel. The periodicity of the flow is, however, damped in the downstream region of a long duct. This damping may be attributed to the influence of side walls on the flow structure.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 17 (1993), S. 975-993 
    ISSN: 0271-2091
    Keywords: Navier-Stokes equations ; Mass and momentum balance ; Non-orthogonal control volume ; Gauss-Legendre quadrature ; Pressure correction ; Flow over bluff bodies ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A numerical method for predicting viscous flows in complex geometries has been presented. Integral mass and momentum conservation equations are deploved and these are discretized into algebraic form through numerical quadrature. The physical domain is divided into a number of non-orthogonal control volumes which are isoparametrically mapped on to standard rectangular cells. Numerical integration for unsteady mementum equations is performed over such non-orthogonal cells. The explicitly advanced velocity components obtained from unsteady momentum equations may not necessarily satisfy the mass conservation condition in each cell. Compliance of the mass conservation equation and the consequent evolution of correct pressure distribution are accomplished through an iterative correction of pressure and velocity till divergence-free condition is obtained in each cell. The algorithm is applied on a few test problems, namely, lid-driven square and oblique cavities, developing flow in a rectangular channel and flow over square and circular cylinders placed in rectangular channels. The results exhibit good accuracy and justify the applicability of the algorithm.This Explicit Transient Algorithm for Flows in Arbitrary Geometry is given a generic name EXTRAFLAG.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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