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1984 (1)
1980 (1)
1Author    FrancisJ. Bonner, Lars-Olof SundelöfRequires cookie*
 Title    Thermal Diffusion as a Mechanism for Biological Transport  
 Abstract    Accumulated experimental information is used to assess the possible significance o f thermal diffusion to mass transport in living matter. Possible thermal gradients across m em branes, a single living cell, and an ensem ble o f such cells (e.g. an organ, tumor, etc.) are estim ated. The corresponding model calculations, although not describing the biological process in detail, lead to conclusions about the possibilities for thermal diffusion as follows. A dequate thermal gradients to support substantial thermal diffusion could exist across biological m embranes. Thermal diffusive flow would becom e significant when ordinary Fickian diffusion is sufficiently sup­ pressed, e.g. in more concentrated systems near critical points o f solution (i.e. near incipient phase separations). Conditions favorable to thermal diffusion functioning as a m echanism for active transport appear possible. Thermal diffusion appears much m ore im portant for transport into and out o f an ensemble o f cells than into or out o f a single cell. Such mass transport by thermal diffusion could assume a sizable m agnitude for an ensem ble o f cells with the dim ensions o f an organ or a tumor. 
  Reference    Z. Naturforsch. 39c, 656 (1984); received October 14 1980/N ovem ber 23 1983 
  Published    1984 
  Keywords    Thermal Diffusion, Biological Transport, M embranes, Organs, Tumors 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0656.pdf 
 Identifier    ZNC-1984-39c-0656 
 Volume    39 
2Author    B. Kopp, W. LöffelhardtRequires cookie*
 Title    Determination of Progesterone in Vegetative Organs and Cell Organelles of ConvaUaria majalis L. by Radioimmunoassay  
 Abstract    Progesterone was extracted from leaves and subterranean parts o f Convallaria majalis L. and quantified by radioimmunoassay. During the stage o f flowering the content o f progesterone in rhizomes was by a factor o f four higher than in leaves and by a factor o f ten higher than in roots, whereas five weeks later the level o f progesterone was unchanged in rhizomes and roots but was elevated in the leaves. The change in progesterone distribution is discussed in relation to the development o f the plants. At the subcellular level the mitochondrial and microsomal fractions contained the largest quantity o f progesterone in leaf cells. However, significant amounts were also found in the 2 0 0 0 x g fraction com prising nuclei and chloroplasts. 
  Reference    Z. Naturforsch. 35c, 41 (1980); received N ovem ber 14 1979 
  Published    1980 
  Keywords    Convallaria majalis L, Progesterone Determ ination, Organs, Subcellular Distribution, R adio­ immunoassay 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0041.pdf 
 Identifier    ZNC-1980-35c-0041 
 Volume    35