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  • 1
    Electronic Resource
    Electronic Resource
    High pH-values and secretion of ions on leaf surfaces: A characteristic of the phylloplane of Malvaceae (1984)
    Springer
    Cellular and molecular life sciences 40 (1984), S. 935-937 
    Details
    ISSN: 1420-9071
    Keywords: Ion secretion ; leaf surface pH ; Malvaceae ; phylloplane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary All of 19 different species of Malvaceae have high pH-values, pH 9.5 or higher, on one or both surfaces of mature leaves. This is due to the secretion of magnesium and potassium carbonate and bicarbonate. The unusual pH and ionic composition may be important for parasites and pathogens living in the phylloplane of Malvaceae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01946445
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Cytogenetic investigations on development and degeneration of oocytes from juvenile mice (1980)
    Springer
    Anatomy and embryology 161 (1980), S. 9-18 
    Details
    ISSN: 1432-0568
    Keywords: Cytogenetics ; Oocytes ; Development ; Mouse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Oocytes were isolated by mechanical disruption of the ovarian tissue of juvenile mice aged between 8 and 28 days p.p. Different types of oocytes could be distinguished by direct observation using an inverted light microscope. Their relative amount within the oocyte population isolated was determined in relation to age of the animals. The following types were isolated and examined: 1. “Normal” oocytes containing an intact germinal vesicle (that is, a nucleus in dictyate stage). In all age groups 55 to 83% of the oocytes were of this type. Their nuclear developmental stage was determined by studying their capacity to resume meiosis in culture as a function of age. 45% of the oocytes isolated from 15 day old mice were competent to resume meiosis. In mice aged 21 days more than 80% of the oocytes measuring about 80 μm in diameter resumed meiosis in vitro. No further increase in mean diameter or in the amount of competent oocytes could be found in older mice. 2. Degenerating oocytes. Five different types could be distinguished. a) “Atretic” oocytes present in all age groups investigated with pyknotic or disintegrating nuclei; b) “Precociously matured” oocytes first observed in mice aged 15 days containing normal diakinesis-and metaphase II-chromosomes; c) “Vacuolized” oocytes first isolated on day 18 having metaphase II-chromosomes scattered within the cytoplasm; d) “Fragmented” oocytes also first observed 18 days p.p. containing chromatin dissociated into micronuclei of different sizes within the cytoplasmic fragements; e) “Ghost” oocytes present in all age groups, characterized by the disintegration of the cytoplasm so that only the surrounding zona pellucida can be clearly seen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304665
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Surface characteristics of oocytes from juvenile mice as observed in the scanning electron microscope (1980)
    Springer
    Anatomy and embryology 161 (1980), S. 19-27 
    Details
    ISSN: 1432-0568
    Keywords: Surface characteristics ; Oocytes ; Mouse ; Scanning Electron Microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The in vivo and in vitro development of the zona pellucida as well as the vitelline membrane surface of oocytes isolated from juvenile mice aged between 8 and 30 days p.p. were investigated by scanning electron microscopy. In vivo a consistent development of the zona pellucida surface can be observed, namely the formation of a fibrous network like structure interspersed with numerous pores. After enzymatic removal of the zona pellucida the surface of the vitelline membrane was studied. In “normal” oocytes with intact germinal vesicles, microvilli were distributed over the entire oocyte surface in all age groups investigated. After resumption of meiosis in vitro a characteristic differentiation on the vitelline membrane occurs. A glabrous polar region appears in primary oocytes and a glabrous polar body in secondary oocytes. The same differentiation in surface organization could be observed in the in vivo precociously matured oocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00304666
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Crystallized hemoglobin inRhodnius prolixus after a blood meal on guinea-pig (1983)
    Springer
    Cellular and molecular life sciences 39 (1983), S. 1335-1338 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Several blood-sucking arthropods, after a blood meal, are able to store the hemoglobin from their hosts in a crystalline state in their digestive system5,15,20. Guinea-pig hemoglobin crystallizes in the stomach of the reduviid bugRhodnius prolixus in two different crystal types. We show them to be crystallographically identical and to contain the same liganded state of hemoglobin, i.e. they represent different habits of the same crystal modification. The hemoglobin crystallizes in oxy-form and ages in the crystalline state, first to aquomethemoglobin and subsequently to hemichrome without crystal cracking. The rate of aging appears to be the same for both types. The hemoglobin crystal modification observed in the digestive system ofRhodnius prolixus is highly host- but not parasite- specific. The same modification is also observed in vitro and inOrnithodorus moubata, an arachnid whose digestive system differs considerably from that of the insectRhodnius. The retainment period of the crystals represents a long term host-record of possible medical interest.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01990090
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    Paper (German National Licenses)
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