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  • 1
    Electronic Resource
    Electronic Resource
    Electrorotational spectra of protoplasts generated from the giant marine algaValonia utricularis (1997)
    Springer
    Protoplasma 196 (1997), S. 123-134 
    Details
    ISSN: 1615-6102
    Keywords: Valonia utricularis ; Protoplast preparation ; Electrorotation ; Microstructures ; Dispersion ; Polarization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Protoplasts ofValonia utricularis lacking the large central vacuole can be generated by cutting multi-nucleated, giant “mother” cells into small pieces after short exposure to air. When the protoplasmic content was squeezed out into sea water, irregularly shaped, green coloured aggregates were formed which changed into spherical protoplasts (radius of 20–60 μm) after about 2 h. In these protoplasts the dense internal material (consisting mainly of organelles) was separated from the plasmalemma by a thin transparent layer containing a large number of small lipid vesicles. Cell wall regeneration occurred rapidly after protoplast formation. A central vacuole developed after about 10h. The regenerated cells continued to grow and were viable for several months. Electrorotation studies on 2–3 h old protoplasts at pH 7 in low- and fairly high-conductivity solutions showed one or two anti-field rotation peaks (depending on medium conductivity) between 10 kHz to 1 MHz as well as one cofield rotation peak between 10 MHz to 100 MHz. The rotation spectra could not be fitted on the basis of the single- (or multi-) shell model (i.e., by modelling the cells as a homogeneous sphere surrounded by one or more layers). However, fairly good agreement between the experimental data and theory could be obtained by assuming that the rotational behaviour of the protoplasts depends not only on passive electrical properties of the plasmalemma but is influenced by “mobile charges” of carrier transport systems and/or the dielectric behaviour of the aggregated chloroplasts and vesicles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279561
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  • 2
    Electronic Resource
    Electronic Resource
    Catecholaminergic innervation of the chicken ovary (1983)
    Springer
    Cell & tissue research 230 (1983), S. 431-450 
    Details
    ISSN: 1432-0878
    Keywords: Chicken ovary ; Adrenergic innervation ; Cholinergic innervation ; Steroidogenic interstitial cells ; Myosin immunoreactivity ; PNMT ; Choline acetyltransferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The innervation of the chicken ovary was investigated with special emphasis on adrenergic nerves in the follicular wall. Quantitative determinations of catecholamines (CA) by high-performance liquid chromatography and electrochemical detection (hplc-ed) revealed 15.4±3.3 ng/mg protein of norepinephrine (NE) and 3.14 ng/mg protein of epinephrine (E), with even larger amounts in the cranial part of the ovary close to the adrenal gland. Serial sections that had been processed for the visualisation of aminergic nerves (Falck-Hillarp- or glyoxylic acid technique) showed CA localized in nerve-fibre bundles; cell bodies of chromaffin and sympathetic neurons were only found at the ovarianadrenal junction suggesting that ovarian nerves stored considerable quantities of E. An antiserum against bovine phenylethanolamine N-methyltransferase (PNMT, the E-synthesizing enzyme) produced no immunostaining in chicken ovary or adrenal gland, due to a lack of crossreactivity between the antiserum and chicken PNMT. Serial sections processed alternately for the visualisation of aminergic nerves and myosin (from chicken gizzard) immunoreactivity revealed a scarce nerve supply of contractile cells in the theca externa compared to an extraordinarily dense innervation of the endocrine interstitial tissue of the theca interna. This distribution pattern of nerve fibres in the follicular wall was confirmed by electron microscopy in ovarian tissue that had been pretreated with 5- or 6-hydroxydopamine (OHDA). More than 90% of the terminal axons were specifically labeled by these false adrenergic transmitters. Many of these terminals were seen in close contact (20 nm) with steroidogenic cells suggesting a neuromodulatory function of CA in hormone synthesis and/or release. It is yet unclear whether E and NE are stored in separate or identical axon moieties and within the same organelles. Choline acetyltransferase activity, which was taken as a measure for a cholinergic nerve component in the ovary, amounted to only 7% of its adrenal activity. It is suggested that the chicken ovary may serve as an excellent model to investigate the modulatory role of nerves in the endocrine function of the ovary.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213816
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