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  • 1985-1989  (2)
  • 1989  (2)
Source
Material
Years
  • 1985-1989  (2)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Utrastructural study of oogenesis and oocytic degeneration in Pecten maximus from the Bay of St. Brieuc (1989)
    Springer
    Marine biology 103 (1989), S. 339-348 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An ultrastructural study of oocytic development enabled the identification of changes occurring during oogenesis in Pecten maximus collected from the Bay of St. Brieuc, France, in 1987. “Auxiliary cells”, closely associated with developing oocytes were observed. Each oocyte seems to be associated with only one secretory cell, which is characterised by an abundant rough endoplasmic reticulum at the onset of vitellogenesis. Contact between this cell and a developing oocyte is maintained by a desmosome-like junction which can be observed when the vitelline coat is formed. These “auxiliary cells” seem to play a trophic role in vitellogenesis, and may be involved in the formation of the vitelline coat of the oocytes. Oocytic degeneration is discussed in detail; in this species, it is a continuous phenomenon of varying intensity throughout the year. The ultrastructural changes resulting in lysis of the oocyte are described, and the evolution of atretic oocytes is examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397268
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Chemoautotrophic symbionts and translocation of fixed carbon from bacteria to host tissues in the littoral bivalve Loripes lucinalis (Lucinidae) (1989)
    Springer
    Marine biology 101 (1989), S. 305-312 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Specimens of Loripes lucinalis (Lucinidae) living in reducing sediments were collected near a sewage outfall at low tide on the Moulin Blanc beach, Brest, France, from January to March 1987. Electron microscope studies revealed numerous Gram-negative-type bacteria in the gill cells. Ribulosebiphosphate carboxylase, a diagnostic enzyme of the Calvin-Benson cycle of CO2-fixation was measured only in the gill extracts. Various tissues of L. lucinalis were examined for activity of APS reductase, (EC 1.8.99.2), ATP sulphurylase (EC 2.7.7.4) and rhodanese (EC 2.8.1.1), enzymes involved in sulphide oxidation. APS reductase was only found in symbiont-containing tissues, i.e., gills. These enzymatic studies characterise the symbionts as chemoautotrophic sulphide-oxidizing bacteria. Histoautoradiography demonstrated that part of the carbon dioxide fixed by symbiotic bacteria in the gills is translocated to symbiont-free tissues of the bivalve. The ultrastructure of the gill is detailed and a nomenclature based on established and new terminology is proposed to describe the various cellular types comprising the gill filament.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428126
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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