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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 3672-3693 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Deamination Reactions, 44. Decomposition of 1-Alkylcyclopropanediazonium Ions1-Methyl- (17), 1,2-dimethyl- (41, 44), 1-propyl- (64), 1-(1-methylethyl)cyclopropanediazonium ions (80), and [1,1′-bicyclopropyl]-1-diazonium ions (93) have been generated by alkaline cleavage of the analogous nitrosocarbamates in methanol. Cyclopropyl-allyl transformation and nucleophilic displacement were the only reactions of 17, 41, 44, and 93 while elimination and 1,2-shifts of an α-hydrogen compete increasingly with 64 and 80. The stereochemistry of ring cleavage and nucleophilic displacement has been explored, using 2-D labels in the case of 17 and 93. Cyclopropanediazonium ions (1) and 41 react stereospecifically, 17 and 44 are moderately stereoselective (ca. 85:15), and 93 is entirely unselective. The data indicate a gradual changeover from concerted to stepwise mechanisms. Appreciable stabilization of the positive charge is required to reach the SN1 extreme.
    Notes: 1-Methyl- (17), 1,2-Dimethyl- (41, 44), 1-Propyl- (64), 1-(1-Methylethyl)cyclopropandiazonium-Ionen (80) und [1,1′-Bicyclopropyl]-1-diazonium-Ionen (93) wurden durch alkalische Spaltung der entsprechenden Nitrosocarbamate in Methanol erzeugt. Cyclopropyl-Allyl-Umlagerung und nucleophile Substitution sind die alleinigen Reaktionen von 17, 41, 44 und 93, während bei 64 und 80 Eliminierung und 1,2-Verschiebung eines α-Wasserstoffs zunehmend konkurrieren. Die Stereochemie von Ringöffnung und nucleophiler Substitution wurde untersucht, im Fall von 17 und 93 mit Hilfe von 2-D-Markierung. Cyclopropandiazonium-Ionen (1) und 41 reagieren stereospezifisch, 17 und 44 stereoselektiv (ca. 85:15) und 93 völlig unselektiv. Die Ergebnisse sprechen für einen allmählichen Übergang von konzertierten zu schrittweisen Reaktionsabläufen. Um das SN1-Extrem zu erreichen, ist eine erhebliche Stabilisierung der positiven Ladung erforderlich.
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  • 2
    ISSN: 1432-0983
    Keywords: Triticum aestivum ; Genomic variability ; Mitochondrial DNA ; Somatic tissue culture ; Regeneration ability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Embryogenic and non-embryogenic long-term callus cultures of hexaploid wheat exhibit differences in the organization of their mitochondrial genome. Embryogenic and non-embryogenic fractions of callus cultures initiated from immature embryos of the wheat cultivar “Chinese Spring” have been isolated and subsequently subcultured. DNA-DNA hybridization experiments using labelled cloned wheat mitochondrial DNA fragments have shown that the mitochondrial DNA organization of embryogenic subcultures derived from embryogenic parts of “Chinese Spring” calli is closely related to that of the initial “Chinese Spring” calli, while non-embryogenic subcultures derived from non-embryogenic fragments of “Chinese Spring” calli exhibit a mitochondrial DNA organization similar to that found in non-embryogenic calli derived from cultivar “Aquila”. In addition, somatic tissue cultures initiated from three other non-embryogenic wheat cultivars (“Talent”, “Thésée” and “Capitole”) display mitochondrial DNA arrangements similar to those found in cultivar “Aquila”. These results strongly suggest that, in wheat callus cultures, a particular mitochondrial genome organization is correlated with the ability of cultured cells to regenerate whole plants.
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  • 3
    ISSN: 1432-2242
    Keywords: Wheat ; Somatic tissue culture ; Mitochondrial DNA ; Chondriome variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have previously shown that the mitochondrial genome of long-term tissue cultures prepared from immature embryos of several varieties of cultivated wheat underwent variety-specific rearrangements resulting from either changes in the relative amounts of subgenomic components or from the appearance of novel genomic configurations. In the present work, both categories of rearrangements were studied in long-term tissue cultures initiated from other explants (shoot meristem, young leaf base, young root tip, immature inflorescence) of the same wheat variety (Chinese Spring) and were compared to those previously obtained with immature embryo cultures. Two main patterns of reorganization were found in a region of the mitochondrial genome known to be hypervariable in structure. In addition, some of the novel subgenomic configurations were obviously organ/tissue-specific whereas others were present in more than one type of organ. In several instances, the age of culture was found to determine the degree of mitochondrial DNA rearrangement. The data presented in this study strengthen the hypothesis of an association between a particular organization of the mitochondrial genome in tissue culture and its regeneration capacity.
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  • 4
    ISSN: 1432-2242
    Keywords: Wheat ; Somatic tissue culture ; Regenerated plants ; Mitochondrial DNA ; Chondriome variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have previously shown that tissue cultures derived from various explants of the wheat variety Chinese Spring exhibit organ/tissue-specific changes in the organization of their mitochondrial genome. The aim of this work was to study the influence of passage out of in-vitro culture, and subsequent plant regeneration, on the in vitro “induced” reorganization of this genome. In all cases but one, subgenomic configurations present in both the donor parent and the tissue culture were evident, in corresponding regenerated plants. The presence, in regenerated plants, of subgenomic configurations found in tissue culture but undetectable in the donor parent appeared to be both timeand organ/tissue-dependent. Moreover, when present, these novel organizations were not systematically found in all regenerated plants. Finally, novel subgenomic configurations were specifically detected after passage out of in-vitro culture. As these results were obtained from a single plant variety, they clearly confirm the extreme plasticity of mitochondrial genome structure in response to in-vitro culture.
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  • 5
    ISSN: 1432-2242
    Keywords: Wheat ; Somatic tissue culture ; Regeneration ; Reciprocal crosses ; Mitochondrial DNA variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The transmission of a structurally-hypervariable fraction of the mitochondrial genome has been studied in 42 F1 progenies obtained from reciprocal crosses between self-pollinated alloplasmic wheat plants regenerated after long-term somatic embryogenesis. This fraction of the genome is maternally and stoichiometrically inherited. In contrast, some additional restriction fragments specific to regenerated plants display a more complex mode of sexual transmission: one of the additional fragments was stoichiometrically and systematically inherited whereas two others were detected only in certain F1 hybrids. Assuming that the detection, by Southern analysis, of such a fragment in regenerated plants is due to the amplification of a pre-existing substoichiometric molecule generated by the activation of a rare recombination event, our results suggest that the probability of detecting a novel fragment in the F1 hybrids could be determined by the length of the repeated sequence at which recombination occurs.
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  • 6
    ISSN: 1432-2242
    Keywords: Triticum ; Allopolyploidy ; Mitochondrial DNA ; Somatic tissue culture ; Chondriome variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Southern-blot hybridizations of total DNA to mitochondrial DNA (mtDNA) probes were used to investigate the extent of mtDNA variability in cultures derived from immature embryos of diploid (Triticum monococcum, genomic formula: AA, T. tauschii, genomic formula: DD), allotetraploid (T. durum cv “Creso”, genomic formula: AABB), and allohexaploid (T. aestivum, genomic formula: AABBDD) wheat species. Similar distinct changes in mtDNA organization were observed in in vitro cultures of the derived tetraploid and the hexaploid species with related genomes. The tetraploid and hexaploid species share the B genome and mtDNA variability in in vitro culture is known to be under nuclear control. These results suggest that a study of B genome diploids and other polyploid combinations would now shed light on whether or not mtDNA variability in tissue cultures is under B-genome control.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 152 (1926), S. 347-356 
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 169 (1928), S. 57-80 
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 163 (1927), S. 31-39 
    ISSN: 0863-1786
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 5 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 100 (1967), S. 1507-1514 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Die Untersuchung der Inhaltsstoffe verschiedener Vertreter der Gattung Carlina L. zeigt, daß diese Gattung neben bereits bekannten Verbindungen mehrere neue Substanzen (10, 15, 16, 20) enthält, die in ihrer Struktur geklärt werden konnten. Biogenetisch sind alle Verbindungen recht eng miteinander verwandt.
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