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  • 11
    Electronic Resource
    Electronic Resource
    Effect of dietary cholesterol on the pattern of osmium deposition in the symbiote-containing cells of the pea aphid (1977)
    Springer
    Cell & tissue research 176 (1977), S. 191-203 
    Details
    ISSN: 1432-0878
    Keywords: OsO4 ; Cholesterol ; Symbiotes ; Aphids ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Pea aphids left for 48 h in unbuffered osmium tetroxide show heavy staining of many organelles in the symbiote-containing cells (mycetocytes and sheath), embryos and oenocytes very similar to that characteristic of mammalian sterol-synthesizing cells. However, the staining of the pea-aphid cells is, to a large extent, dependent on the presence of cholesterol benzoate, or free cholesterol, in the aphid's diet. In aphids cultured in vitro with 3H mevalonate in the presence of added cholesterol, the incorporation of label into the cholesterol and lanosterol fractions is significantly reduced. If the dietary cholesterol effects a similar inhibition in vivo, the cholesterol-dependent osmium staining could be due to precursors(s) of cholesterol accumulating in the intracellular sites described. There is also osmium staining of large (normally electron-transparent) vacuoles in mycetocytes, gut and fat body, irrespective of dietary cholesterol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00229462
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    Paper (German National Licenses)
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  • 12
    Electronic Resource
    Electronic Resource
    Effects of antibiotics on intracellular symbiotes in the pea aphid, Acyrthosiphon pisum (1974)
    Springer
    Cell & tissue research 148 (1974), S. 287-300 
    Details
    ISSN: 1432-0878
    Keywords: Symbiotes ; Aphids ; Antibiotics ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of penicillin and chlortetracyline HCl on the fine structure of the intracellular symbiotes of the pea aphid were studied in an attempt to remove the symbiote population. High penicillin concentrations, 1% and 0.1%, caused symbiote breakdown but were toxic and/or repellent to the aphids; at 0.1% specific effects were observed on the symbiotes' cell walls. After the use of 0.01% penicillin in the aphid diet, the symbiotes had abnormal cell walls and were abnormally dilated; however, symbiote division and transmission from one aphid generation to the next seemed unaffected and the aphids appeared normal. Aphids fed 0.1% chlortetracycline failed to reproduce. After 7 days, their symbiotes were found to break down at a high rate but aphid mitochondria were also adversely affected at this stage. Following 0.002% chlortetracycline, the aphids produced aposymbiotic progeny with apparently normal mitochondrial populations; these larvae failed to develop.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00224257
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    Paper (German National Licenses)
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  • 13
    Electronic Resource
    Electronic Resource
    Comparative ultrastructure and blood-brain barrier in diapause and nondiapause larvae of the European corn borer Ostrinia nubilalis (Hübner) (1975)
    Springer
    Cell & tissue research 162 (1975), S. 499-510 
    Details
    ISSN: 1432-0878
    Keywords: Blood-brain barrier ; Moth ; Diapause ; ATPase ; Peroxidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Ultrastructural examination of diapause and nondiapause larval brains of the European corn borer disclosed anatomical differences that may be related to the insect's “blood-brain barrier.” The perineurial type I cells are quite closely appressed in the diapause brain, but thrown into extensive folds with large intercellular spaces in the nondiapause brain. The perineurial type II cells of diapause and nondiapause larvae are basically similar in general ultrastructure, and most likely form the basis for the “blood-brain barrier.” Horseradish peroxidase penetration studies indicated that the outer margin of the perineurial type II cells constitute the limits of infiltration into the brain. An enzymatic component of the “blood-brain barrier” is postulated in this insect. The localization of ATPase in the perineurial type II cells indicates that energy-requiring regulatory mechanisms may be localized here. Metabolic studies with isolated insect brains, coupled with recent evidence from mammalian systems, suggest that glial cells may be of importance in an enzymatic “blood-brain barrier.”
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00209349
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  • 14
    Electronic Resource
    Electronic Resource
    Ultrastructure of pea aphid mycetocytes: Evidence for symbiote secretion (1975)
    Springer
    Cell & tissue research 159 (1975), S. 351-367 
    Details
    ISSN: 1432-0878
    Keywords: Symbiotes ; Aphids ; Vesicles ; Organelles ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A detailed investigation into the ultrastructure of the pea aphid mycetocytes and their contained symbiotes and organelles was carried out with the transmission electron microscope. The most striking observation was the presence of small vesicles in the space between the primary symbiote cell wall and membrane envelope (outer membrane space). The vesicles appear to form by a budding process at the outer cell wall layer. Subsequently, the vesicles, we suggest, may move out into the mycetocyte cytoplasm via a similar budding of the membrane envelope. The Golgi apparatus was found to be an important structural component of the primary mycetocyte; it is continuous with the rough endoplasmic reticulum and the latter, in turn, appears to be closely connected to the primary symbiote membrane envelope. This may be of functional significance. A number of other organelles not previously described in mycetocytes were found, including transparent vacuoles, granular bodies, multivesicular bodies and microfilaments. The chemical composition of the various vesicles and organelles is unknown at present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221782
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    Paper (German National Licenses)
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