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  • 1
    Electronic Resource
    Electronic Resource
    Ribosomes in incompatible pollen tubes in the Solanaceae (1998)
    Copenhagen : Munksgaard International Publishers
    Physiologia plantarum 103 (1998), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Some members of the Solanaceae have a self-incompatibility mechanism preventing self-fertilization. Stylar ribonucleases (S-RNases) are responsible for growth inhibition of self-pollen tubes. A prevalent model postulates that the S-RNases act as intracellular cytotoxins that degrade ribosomal RNA, and possibly also messenger RNA, in the incompatible pollen tubes. Since ribosomes and polysomes are easily noticed with the electron microscope, it should be possible to confirm disintegration of these structures. However, our inspection by electron microscopy revealed the presence of ribosomes and polysomes in pollen tubes formed after self-pollination of the self-sterile species Brugmansia (Datura) suaveolens and Nicotiana alata. There was no decrease over time in the number of bound ribosomes per unit of rough endoplasmic reticulum (RER) membrane. The results indicate that the inhibition of tube growth is not due to a general degradation of ribosomal and messenger RNA. Therefore, the substrate for S-RNases presumably is very specific.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.1998.1030403.x
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  • 2
    Electronic Resource
    Electronic Resource
    Chromoplast development in a carotenoid mutant of maize (1971)
    Springer
    Protoplasma 73 (1971), S. 159-175 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The lethal recessive mutantlycopenic in maize is characterized by the synthesis of lycopene instead of the normal carotenoids. At normal conditions of illumination it loses chlorophyll by photo-oxidation. Seedlings of this mutant and of normal maize were grown at light intensities of 25–30 lux and 500–30,000 lux. Their plastid development was studied by electron microscopy. At low light intensities a kind of mesophyll chloroplast with elongated grana, long unpaired thylakoid segments, and sometimes prolamellar bodies is formed in mutant plants. In corresponding bleached plants the plastids are transformed into chromoplasts containing characteristic lycopene crystalloids similar to those found in tomato fruits. Various stages in this chromoplast development are described and illustrated. Also bundle-sheath plastids were found to develop into chromoplasts. It is concluded that the ultrastructure of plastids in a tissue is influenced by the nature of their pigments and that an altered carotenoid composition therefore can give rise to development of chromoplasts in plants which normally lack such organelles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01275592
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  • 3
    Electronic Resource
    Electronic Resource
    An electron microscope study on photodestruction of plastid ribosomes in β-carotene-deficient mutants ofHelianthus annuus L. (1972)
    Springer
    Protoplasma 75 (1972), S. 215-227 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of light on plastid ribosomes in seedlings of twoβ-carotene-dencient mutants ofHelianthus has been investigated by electron microscopy. Plastid ribosomes occur in mutant seedlings grown in darkness or dim light (about 20 lux) but are absent in seedlings grown under stronger illumination (about 500 lux). Photodestruction of plastid ribosomes has previously been reported in plants treated with amitrole, an inhibitor ofβ-carotene biosynthesis. The possibility that plastid ribosomes are sensitive to light of wavelengths normally absorbed byβ-carotene is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279817
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  • 4
    Electronic Resource
    Electronic Resource
    On the presence of plastids and the eyespot apparatus in a porfiromycin-bleached strain ofEuglena gracilis (1975)
    Springer
    Protoplasma 84 (1975), S. 75-82 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ultrastructural studies were performed on a strain ofEuglena gracilis bleached with the antibiotic porfiromycin. A limited number of organelles could be identified as plastids by their possession of a double envelope and a stroma containing bunches of minute thylakoids, DNA-fibrils and ribosomes. A stigma was situated close to the reservoir. Opposite the stigma a paraflagellar body was observed in the main flagellum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02075944
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  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructural and molecular study of plastid inheritance in Abies alba and some Abies hybrids (1998)
    Springer
    Sexual plant reproduction 11 (1998), S. 284-291 
    Details
    ISSN: 1432-2145
    Keywords: Key words Abies ; Egg cell ; Plastid inheritance ; RFLP ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The ultrastructure of egg cells in Abies alba was examined to elucidate the lack of maternal inheritance of plastids. Before fertilization, maternal plastids are absent in the perinuclar zone containing mainly mitochondria and smooth endoplasmic reticulum. During egg cell development the maternal plastids are transformed into large inclusions which are situated mostly towards the periphery of the egg cell, and finally disintegrate. As a consequence, they do not participate in zygote formation. RFLP analysis of cpDNA of parental trees and their F1 interspecific hybrids (A. alba×A. numidica, A. alba×A. nordmanniana, A. nordmanniana×A. Alba) using HindIII and BamHI showed a paternal mode of cpDNA inheritance. Paternal inheritance has also been found with PCR/RFLP analysis of cpDNA from parental trees and their hybrids (A. alba×A. pinsapo, A. pinsapo×A. alba, A. pinsapo×A. numidica) using ApaI and HaeIII digests, as well as in the crosses of A. cephalonica×A. nordmanniana, A. nordmanniana×A. cephalonica, A. cephalonica×A. numidica using TagI digests.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050155
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