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  • 1
    ISSN: 1432-2048
    Keywords: Pollen (development) ; Lilium (pollen development) ; mRNA expression (pollen development) ; Microgametophyte ; Microspore ; Nicotiana (pollen development)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Homogeneous populations of developing microspores and pollen from anthers of lily (Lilium longiflorum Thumb.) and tobacco (Nicotiana tabacum L.) show a continuous production of biomass, reaching a maximum in young pollen. The rate of RNA synthesis was 460 fg · h−1 in young binucleate cells, 138 fg · h−1 in late binucleate cells and 56 fg · h−1 in microspores. The mRNA population in developing pollen can be separated into three groups. In the first group, certain types of mRNAs are present at a constant level during all stages of development. A second group is characteristic of young pollen and increases quantitatively until anthesis. A third group is seen transiently; to this belong mRNAs present only before mitosis or at a distinct cell stage after mitosis. Some of the translation products of this latter group of mRNAs showed similarities between lily and tobacco on two-dimensional gels in respect of molecular weight and isolectric point, indicating that those mRNAs and proteins play a role in the regulation of pollen development.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2145
    Keywords: In situ hybridization ; Pollen-specific gene expression ; mRNA ; Confocal laser scanning microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The application of confocal laser scanning microscopy together with in situ hybridization experiments in tobacco pollen enabled a detailed localization of a pollen-specific mRNA. The three-dimensional distribution of this specific mRNA over the whole pollen grain was reconstructed by means of optical sections of one specimen.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2145
    Keywords: Microsporogenesis ; In-vitro pollen maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Immature pollen grains of Nicotiana tabacum L., cv ‘Petit Havana’ were isolated at the mid-binucleate stage and cultured in vitro. During the first 66 h of in-vitro culture the pollen developed the same ability to set seed and germinate as pollen matured in vivo. No fertile pollen was produced when protein synthesis was inhibited temporarily at an early stage of development. In the case of inhibition at day 2 of development a delay in the total time necessary for maturation was observed that was equal to the length of time the inhibitor was applied. Hybridization experiments with a pollen-specific cDNA probe showed that the pattern of gene expression in vitro was similar to that in vivo. However, the model system differs from natural pollen development with respect to the dehydration period, which is absent in the model system, and the synthesis of proteins. Protein synthesis of in-vitro cultured pollen differed significantly from that of pollen developing in vivo, even though pollen maturation in vitro proceeded in the same time as in vivo, and led to fully matured fertile pollen. Pollen development in vitro is thus an ideal model system for studying gene expression in relation to fertility and for experimental manipulation of microsporogenesis.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5028
    Keywords: anther ; in situ hybridization ; microspore development ; microspore-specific gene ; Nicotiana tabacum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The characterization of a gene with a unique microspore-specific expression pattern is reported. Isolated microspores from tobacco were used to synthesize a cDNA library. Clones that did not hybridize to leaf cDNA were further characterized by northern analysis. One clone proved to be a microspore-specific cDNA, representing a transcript of 650 nt. The corresponding gene, NTM19 (Nicotiana tabacum microspore-specific), was isolated and its sequence analysed. The gene encodes a protein of 10.8 kDa with a pI of 6.92 and a putative signal sequence at the N-terminus. A localization study revealed a unique spatial and temporal distribution. The transcript was only detected in the unicellular microspore. No hybridization signals were observed in other pollen developmental stages, nor in the surrounding anther tissues or other vegetative tissues of the plant. Therefore it can be concluded that NTM19 is a gene with a highly microspore-specific character according to both localization and stage of expression. Southern blot analysis demonstrated the presence of a small gene family. The occurrence of TNM19 was investigated in a range of closely and distantly related species and was found to be present in other solanaceous species, including the ancestors of tobacco and in a monocot species.
    Type of Medium: Electronic Resource
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