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  • 1
    Electronic Resource
    Electronic Resource
    Correction The role of mat-forming diatoms in the formation of Mediterranean sapropels (1999)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 399 (1999), S. 84-84 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Nature 398, 57–61 (1999) In this Letter, the legend to Fig. 2 has the descriptions switched for the last two panels. The image shown in Fig. 2c is in fact of H. hauckii , with scale bar 20 µm, and that in Fig. 2d is of P. ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/20011
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  • 2
    Electronic Resource
    Electronic Resource
    The role of mat-forming diatoms in the formation of Mediterranean sapropels (1999)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 398 (1999), S. 57-61 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The origins of sapropels (sedimentary layers rich in organic carbon) are unclear, yet they may be a key to understanding the influence of climate on ocean eutrophication, the mechanisms of sustaining biological production in stratified waters and the genesis of petroleum source rocks. Recent ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/18001
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  • 3
    Electronic Resource
    Electronic Resource
    Structural changes occurring in interrenal tissue of the duck (Anas platyrhynchos) following adenohypophysectomy and treatment in vivo and in vitro with corticotropin (1979)
    Springer
    Cell & tissue research 196 (1979), S. 429-447 
    Details
    ISSN: 1432-0878
    Keywords: Interrenal tissue (birds) ; Ultrastructure ; Corticotropin ; Adenohypophysectomy ; Morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Adrenal glands from ACTH-treated intact ducks and chronically adenohypophysectomized ducks showed clear zonation into a subcapsular zone (SCZ) and an inner zone (IZ). Adenohypophysectomy caused ultrastructural changes in the IZ but not in the SCZ cells. These included increases in lipid droplets, changes in mitochondrial cristae from tubular to shelf-like, and changes in the shape of the nuclei from spherical to crenated. These changes were reversed by treatment with ACTH. Also, cells of the IZ, but not the SCZ, of adrenals from intact birds given ACTH showed more SER, more dense bodies, fewer lipid droplets and more prominent Golgi complexes. IZ cells incubated in buffer containing no ACTH developed mitochondria with shelf-like cristae and numerous opaque granules in the matrix. Exposure to buffer containing ACTH caused the mitochondrial cristae to become tubular and the matrix granules either decreased in number or disappeared. The granules could be extracted by incubating sections with chelating agents. The mitochondria in SCZ cells did not respond structurally to the presence of ACTH in the incubation medium but the matrix granules, like those in IZ cells, responded to the presence of chelating agents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00234738
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  • 4
    Electronic Resource
    Electronic Resource
    Changes in corticotropic responsiveness and mitochondrial ultrastructure of adrenocortical cells from the inner zone of the duck (Anas platyrhynchos) adrenal gland: The effects of cycloheximide, puromycin, and chloramphenicol (1981)
    Springer
    Cell & tissue research 221 (1981), S. 45-57 
    Details
    ISSN: 1432-0878
    Keywords: Adrenal zonation ; Corticosterone ; Mitochondrial ultrastructure ; Protein synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Tissue slices from the inner zone of the adrenal showed no ultrastructural abnormalities after being superfused with Krebs-Henseleit buffer for more than 2 h. Slices superfused with medium containing no ACTH produced only traces of corticosterone and most of the mitochondria had shelf-like cristae. Exposure to medium containing ACTH (1 μg 1-24 ACTH · ml-1) caused a significant increase in the release of corticosterone and the mitochondria developed tubular cristae. Cycloheximide and puromycin inhibited, in a dose-dependent manner, the release of corticosterone from tissue slices superfused with medium containing ACTH. A low concentration of cycloheximide in the medium (0.02 μg · ml-1) had only a slight effect on hormone release but many of the mitochondria developed dark matrixes and shelf-like or disrupted cristae. At higher concentrations of cycloheximide (0.2 μg · ml-1) the release of corticosterone was suppressed and when the concentration was increased to 2.0 μg · ml-1 it was blocked completely; each of these higher concentrations of cycloheximide caused the mitochondria to develop dense matrixes and shelf-like cristae. The inhibitory effects of cycloheximide on the corticotropic responsiveness of superfused tissue slices were reversible. Dependent upon the concentration, the addition of puromycin to the medium also caused, either partial (1.0 and 10.0 μm · ml-1) or complete (100 μg · ml-1), suppression of hormone release from slices superfused with medium containing ACTH; at the same time, the formation of tubular cristae in the mitochondria was blocked. Chloramphenicol had no effect on either hormone release or mitochondrial ultrastructure in the adrenocortical cells from the inner zone of the gland. It is suggested that a specific protein, synthesized in the cytoplasm, is necessary to accomplish the conformational changes in the mitochondrial cristae that accompany the full elaboration of corticotropin-induced hormone synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216568
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  • 5
    Electronic Resource
    Electronic Resource
    Evidence for the zonation of interrenal tissue in the adrenal gland of the duck (Anas platyrhynchos) (1978)
    Springer
    Cell & tissue research 192 (1978), S. 363-379 
    Details
    ISSN: 1432-0878
    Keywords: Adrenal glands ; Birds ; Ultrastructure ; Corticosterone ; Zonation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Although interrenal tissue from the intact duck does not show a clear zonation when examined by light microscopy, the tissue does develop a well defined zonation following exposure to high and low levels of corticotropic stimulation. Under these conditions clear ultrastructural differences are seen between cells of the subcapsular zone (SCZ) and the inner zone (IZ). Based on these observations, the ultrastructure of tissue from intact birds was examined retrospectively and in addition, cell sizes and the relative volumes and areas of intracellular components were measured morphometrically. These analyses reveal morphological and quantitative differences between cells from the IZ and the SCZ. Cells of the IZ have small rounded nuclei, extensive smooth endoplasmic reticulum (SER) and mitochondria with tubular cristae, whereas cells from the SCZ contain pleomorphic nuclei, less SER and mitochondria with shelf-like cristae. The mean cell volume in the IZ is significantly less than that in the SCZ. In the SCZ cells the volume densities (volume per unit volume cytoplasm) of mitochondria and lipid droplets and the surface densities (area per unit volume cytoplasm) of the outer mitochondrial membranes are significantly greater than those in IZ cells. Conversely, in the cells of the IZ the volume densities of the nuclei and dense bodies and the surface density of the SER are greater than the corresponding values estimated for the cells of the SCZ. Although the mitochondria comprise a smaller fraction of the mean volume of IZ cells than SCZ cells, the total surface area of the cristae is approximately the same in the cells of both zones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00212319
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  • 6
    Electronic Resource
    Electronic Resource
    The fine structure of the interrenal cells of the duck (Anas platyrhynchos) with evidence for the possible exocytotic release of steroids (1977)
    Springer
    Cell & tissue research 183 (1977), S. 203-220 
    Details
    ISSN: 1432-0878
    Keywords: Adrenal glands ; Birds ; Corticosterone ; Secretions ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The duck interrenal cell possesses ultrastructural characteristics common to other steroid-secreting cells. Lipid droplets and mitochondria are abundant and lie principally at the apical end of the cell. Lipid droplets are not membrane-limited. Cisternae of smooth endoplasmic reticulum that are occasionally continuous with the less abundant rough endoplasmic reticulum are a prominent feature of the interrenal cell. Tubular profiles of rough endoplasmic reticulum often lie tangentially to mitochondria and ribosomes are either free, grouped in polyribosomal clusters, or bound to the endoplasmic reticulum. Mitochondria possess tubular cristae in the inner regions of the gland and frequently contain a paracrystalline array of small 10nm (o.d.) tubules and less frequently a hexagonal array of 40nm trilaminar rings. Other cytoplasmic components include dense bodies, residual bodies, microtubules, microfilaments and specialized single membrane-bound vesicles. Gap junctions, intermediate junctions and interdigitating processes constitute the main intercellular associations. No tight junctions were identified. The single membrane-bound vesicles which are occasionally filled with a low electron-dense, lipid-like material form septate-like “junctions” with the plasma membrane. The septa bridge an intracellular gap of 15–17 nm. The vesicles are usually located near the subendothelial space at the basal and basilateral regions of the cell. Occasionally, vesicles fuse with the plasma membrane. It is suggested that these vesicles represent morphological evidence for the exocytotic release of steroid hormones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226620
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  • 7
    Electronic Resource
    Electronic Resource
    Functional significance of interrenal cell zonation in the adrenal gland of the duck (Anas platyrhynchos) (1979)
    Springer
    Cell & tissue research 201 (1979), S. 23-36 
    Details
    ISSN: 1432-0878
    Keywords: Adrenal zonation ; Corticosterone ; Aldosterone ; Birds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Slices of whole adrenal gland tissue, incubated in vitro in the presence of ACTH for 1 h and 2 h produced corticosterone and aldosterone in constant ratio (16∶1). Tangential slices taken from the region immediately below the connective tissue capsule and slices taken from deeper regions of the gland consisted primarily of cells conforming to the distinct structural characteristics of the subcapsular zone (SCZ) and inner zone (IZ) tissues respectively. When samples were incubated in the presence of ACTH for 1 h and 2 h, the interrenal cells of the SCZ produced relatively more aldosterone than cells taken from the IZ of the gland. The corticosterone: aldosterone ratio for the IZ after 1 h (68∶1) and after 2 h (102∶1) were ten times greater than the ratios for the SCZ after 1 h (7∶1) and after 2 h (10∶1). The SCZ slices were not more than 60 cells thick and consisted of cells arranged in cords. These cells contained irregular nuclei, mitochondria with shelf-like cristae and a moderate abundance of smooth endoplasmic reticulum. In contrast, the production of large amounts of corticosterone by the cells of the IZ was associated with tissue containing more vascular space than the SCZ and the cells contained large round nuclei surrounded by an abundance of smooth endoplasmic reticulum and the mitochondria had tubular rather than shelf-like cristae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238044
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