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  • 1
    Electronic Resource
    Electronic Resource
    Ultrastructural studies on plastids of generative and vegetative cells in Liliaceae (1986)
    Springer
    Theoretical and applied genetics 72 (1986), S. 840-844 
    Details
    ISSN: 1432-2242
    Keywords: Chlorophytum comosum ; First pollen mitosis ; Male plastid inheritance ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The behaviour of plastids and mitochondria during the formation and development of the male gametophyte of Chlorophytum comosum has been investigated using electron microscopy. During first pollen mitosis an intracellular polarization of plastids occurs in that the plastids are clustered in the centre of the microspore. The originating generative cell normally lacks plastids. Only in a small number of microspores have plastids been observed near the dividing nucleus of the microspore and later on in the generative cell. These observations agree with the genetic investigations of Collins (1922) on the mode of plastid inheritance which demonstrated a small amount of biparental plastid inheritance in Chlorophytum. The cytological mechanisms underlying plastid polarization during the first pollen mitosis are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00266555
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructural studies on plastids of generative and vegetative cells inLiliaceae 3. Plastid distribution during the pollen development inGasteria verrucosa (Mill.) Duval (1985)
    Springer
    Protoplasma 124 (1985), S. 123-129 
    Details
    ISSN: 1615-6102
    Keywords: First pollen mitosis ; Gasteria verrucosa ; Male plastid inheritance ; Pollen development ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This paper describes the development of pollen grains ofGasteria verrucosa from the late microspore to the mature two-cellular pollen grain. Ultrastructural changes and the distribution of plastids as a result of the first pollen mitosis have been investigated using light and electron microscopy. The microspores as well as the generative and the vegetative cell contain mitochondria and other cytoplasmic organelles during all of the observed developmental stages. In contrast, the generative cell and the vegetative cell show a different plastid content. Plastids are randomly distributed within the microspores before pollen mitosis. During the prophase of the first pollen mitosis the plastids become clustered at the proximal pole of the microspore. The dividing nucleus of the microspore is located at the distal pole of the microspore. Therefore, the plastids are not equally distributed into both the generative and the vegetative cell. The possible reasons for the polarization of plastids within the microspore are briefly discussed. The lack of plastids in the generative cell causes a maternal inheritance of plastids inGasteria verrucosa.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279731
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Reproduction inTriticale (1987)
    Springer
    Protoplasma 139 (1987), S. 100-104 
    Details
    ISSN: 1615-6102
    Keywords: Triticale ; Ultrastructure ; Fertilization ; Karyogamy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Karyogamy during fertilization inTriticale starts about 60 minutes after pollination. It was studied in the egg and the central cell by electron microscopy. The fusion of the sperm cell nuclei with the egg and central cell nuclei begins with nuclear envelope fusion presumably with participation of the endoplasmic reticulum cisternae. Initially, fusion is restricted to small bridges between the nuclei. It is accompanied by the appearance of intracisternal lipid droplets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01282280
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    An alpha modulation index for electroencephalographic studies using complex demodulation (2000)
    Springer
    Medical & biological engineering & computing 38 (2000), S. 306-310 
    Details
    ISSN: 1741-0444
    Keywords: Complex demodulation ; Alpha rhythm ; Alpha modulation ; Electroencephalogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract An automated technique for measuring the relative amount of amplitude modulation of electroencephalographic (EEG) alpha activity is developed to increase the number of existing tools for differentiating the various types of alpha activity. EEG data collected from 12 normal males is used to characterize alpha modulation frequency characteristics. From these findings, a complex demodulation method is constructed to extract the amplitude modulation envelope of alpha activity from an epoch of EEG data while disregarding both continuous amplitude alpha activity and activity outside the alpha band. A threshold technique is then used to determine the relative amount of modulation contained within the data epoch. This metric is termed the alpha modulation index (AMI). Good correlation (R2=0.86) is found when automated scoring results are compared with manual scoring of physiologic EEG alpha modulation. The flexibility of this technique makes it easily adaptable to other EEG frequency bands and applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02347051
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    Paper (German National Licenses)
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