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  • Analytical Chemistry and Spectroscopy  (9)
  • Amino Acid Sequence  (4)
  • Anther culture  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Induced androgenesis in alfalfa (Medicago sativa L.) (1995)
    Springer
    Plant cell reports 14 (1995), S. 249-252 
    Details
    ISSN: 1432-203X
    Keywords: Alfalfa ; Anther culture ; Androgenesis ; Haploids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Anthers of 10 alfalfa (Medicago sativa L.) lines were used as initial material for the production of androgenic haploids. More than 30 variants of nutrient media were tested. Twenty five different treatments with low temperatures and gamma rays were tried in order to find optimal conditions for callus induction and organogenesis. The genotype, stage of microspore development, phytohormonal composition of the nutrient media and pretreatment with physical agents, alone or in combination, affected the efficiency of organogenesis and regeneration in anther cultures of alfalfa. Plants exhibited a high degree of variability in their chromosome number. Haploids, dihaploids and mixoploids were obtained. Cytological studies of in vitro pollen development revealed the origin of the regenerants from microspores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00233643
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  • 2
    Electronic Resource
    Electronic Resource
    Induced androgenesis in tomato (Lycopersicon esculentum Mill.) I. Influence of genotype on androgenetic ability (1998)
    Springer
    Plant cell reports 17 (1998), S. 968-973 
    Details
    ISSN: 1432-203X
    Keywords: Key words Tomato ; Anther culture ; Androgenesis ; Genotype
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The androgenetic ability of 85 Lycopersicon esculentum Mill. genotypes was tested. Callus was induced from anthers of 53 lines and hybrids. Regeneration of plants was obtained only from calli of 15 genotypes. The data obtained clearly showed that the genotype affects induced androgenesis in tomato. The in vitro response of anthers from the cultivars Roma, Pearson, San Marzano, Por, Sar, Vigapol, Day, David and Start, containing the ms 1035 gene, which is responsible for male sterility in tomato, confirm the strongly expressed dependence of both callus induction and organogenetic potential on the homozygous or heterozygous state of that gene. A protocol of callus induction, organogenesis and plant regeneration has been developed. More than 6000 regenerants have been obtained. Most of them showed different morphological alterations and variations in chromosome number (n, 2n, 4n). Some are interesting as source material for tomato breeding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050519
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  • 3
    Electronic Resource
    Electronic Resource
    Induced androgenesis in tomato (Lycopersicon esculentum Mill). II. Factors affecting induction of androgenesis (1998)
    Springer
    Plant cell reports 18 (1998), S. 312-317 
    Details
    ISSN: 1432-203X
    Keywords: Key words Androgenesis ; Anther culture ; Temperature ; Gamma rays ; Tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence on androgenesis of donor plant growth conditions, anther size and developmental stage of the microspore, medium composition and different anther treatments prior to culture was investigated in L. esculentum Mill. cv Roma and its hybrids. Growth conditions of donor plants affected the induction of tomato androgenesis. Anthers isolated from plants grown in the greenhouse during winter at high humidity and in short days possessed higher androgenetic ability than those grown in the field. The physiological state and age of the donor plants also influenced the processes investigated. Regarding the developmental stage of microspores, the period from prophase to telophase II is optimal for tomato anther implantation. More then 20 culture media were tested. Two, based on Murashige and Skoog medium were selected as most favourable for callus induction, organogenesis and regeneration. The effect on callus induction of 2ip in combination with indole-3-acetic acid (IAA) was greater than that of zeatin and IAA. Zeatin promoted entire plant regeneration. A highly significant interaction between genotype and medium was observed. Temperature and gamma ray treatments of anthers enhanced callus production, shoot formation and plant regeneration. Treatments at 4 °C (48 h) and 10 °C (9 days) stimulated these processes. Combined treatment of anthers with 4 Gy and 10 °C for 9 days was the most efficient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050578
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  • 4
    Electronic Resource
    Electronic Resource
    Nuclear magnetic resonance studies of internal rotation - IIIFor Part II, see Ref. 1. Rotational barriers in META- and PARA-substituted N, N-dimethylcinnamamides (1971)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 3 (1971), S. 551-556 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers about the C—N bond of eight m- and p-substituted N, N-dimethyl cinnamamides have been determined by the iterative total line shape NMR method. The ΔG298·2-≠ values have been correlated with the substituent constants σ, σn and σ+. By comparison of the results with literature data, some conclusions about the accuracy of the barrier determination as well as the transmittance of polar effects in conjugated amides have been drawn.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270030509
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  • 5
    Electronic Resource
    Electronic Resource
    Dynamic NMR: A new intensity ratio for evaluation of lifetime in paripartite A ⇌ B systems (1976)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 8 (1976), S. 132-136 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple formula for evaluation of rates of exchange in paripartite A ⇌ B systems is introduced. It is concerned only with the intensity ratio in a two-site system in much the same way as that of Rogers and Woodbrey, but the new formula is also applicable above the coalescence point of the spectrum. The formula has been applied to the classical case of N,N-dimethyltrichloroacetamide. An error analysis demonstrates that the approximations inherent in the derivation of the new formula lead to smaller errors than do those of Rogers and Woodbrey.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270080306
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  • 6
    Electronic Resource
    Electronic Resource
    Dynamic NMR: A single operational parameter approach for evaluation of lifetime in an uncoupled, equally populated AB system (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 16-19 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two simple formulae involving only one variable are presented for the simple and rapid estimation of the mean lifetime (τ) of exchange in uncoupled, paripartite AB systems. These formulae are shown to provide τ values comparable to those obtained from total line-shape analysis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270060106
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  • 7
    Electronic Resource
    Electronic Resource
    Nuclear magnetic resonance studies of internal rotation. VFor Part IV, see Ref. 1. - Rotational barriers of acetylenic amides (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 508-509 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers about the C—N bond of the N,N-dimethylamides of propiolic, methylpropiolic and phenylpropiolic acids have been determined by the iterative total line shape nuclear magnetic resonance method.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270060913
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  • 8
    Electronic Resource
    Electronic Resource
    Nuclear magnetic resonance studies of internal rotation: IVFor Part III, see Ref. 1. - rotational barriers and conformation of phthalic amides (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 20-22 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The rotational barriers about the C—N bond of the N,N,N′,N′-tetramethyldiamides of phthalic, isophthalic and terephthalic acids have been determined by the iterative total line shape NMR method. Some evidence about the conformation of these compounds in solution has also been obtained by infrared and dipole moment studies.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270060107
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  • 9
    Electronic Resource
    Electronic Resource
    Restricted rotation of the phenyl group in β-hydroxyphosphonates: Dynamic NMR and semiempirical studies (1994)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 32 (1994), S. 639-645 
    Details
    ISSN: 0749-1581
    Keywords: NMR ; 1H NMR ; 13CNMR ; Dynamic NMR ; β-Hydroxyphosphonates ; Restricted rotation ; Steric effects ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Free energies of activation, ΔG298≠, for the rotation of the phenyl group in the range of 46.06-63.25 kJ mol-1 were observed in some model β-hydroxyphosphonates. These barriers were found to depend on the type of substituents at the phosphorus atom and on the substituents at the β-position with respect to the phenyl ring. The steric origin of this observation is discussed. Dynamic NMR studies were performed in order to determine the activation parameters for the exchange process. For that purpose, variable-temperature 1H and 13C NMR spectra were treated by non-iterative, iterative and iterative double-fit procedures. MNDO, AM1 and PM3 theoretical calculations of the barriers for three of the compounds studied are reported and results are compared with the experiments. It is found that the PM3 results are very close to the experimental data.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260321102
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  • 10
    Electronic Resource
    Electronic Resource
    Dynamic NMR: A new procedure for the estimation of mixing times in the 2D EXSY experiments. A four-site exchange system studied by 1D and 2D EXSY spectroscopy (1995)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 33 (1995), S. 739-744 
    Details
    ISSN: 0749-1581
    Keywords: 1H NMR ; 2D EXSY NMR ; mixing time ; complete lineshape analysis ; double-fit method ; barriers to restricted rotation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure for the estimation of the mixing time between the last two 90° pulses in the classic three-pulse sequence NOESY/EXSY is proposed and tested and some considerations for the treatment of the two-dimensional (2D) 1H NMR exchange spectra are given. The rate constants are thus obtained with reasonable precision. This procedure was followed to obtain the 2D spectra of the model compound α-[bis(dimethylamino)methylene]-4-nitrophenylacetonitrile, which represents a four-site exchange system. The barriers to restricted rotations found in this compound were also determined from one-dimensional (1D) 1H NMR spectra, which were processed with the iterative complete lineshape analysis (CLSA) method. The double-fit approach was incorporated in the CLSA method. It is shown that the results from the 2D dynamic NMR spectral studies corroborate those obtained by the CLSA double-fit method.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260330909
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