The Bacterial Endosymbiosis of the Gutless Nematode, Astomonema Southwardorum: Ultrastructural Aspects

The recently described gutless Astomonema southwardorum Austen, Warwick & Ryan 1993, from North Sea methane seeps lives in symbiosis with oval, extracellular bacteria completely filling the lumen of a modified gut. The bacterial strand is tightly lined by a thin layer representing very long inte...

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Bibliographic Details
Published in:Journal of the Marine Biological Association of the United Kingdom 1995-02, Vol.75 (1), p.153-164
Main Authors: Giere, Olav, Windoffer, Reinhard, Southward, Eve C.
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
Animals
Autoecology
Biological and medical sciences
Fundamental and applied biological sciences. Psychology
Marine
Protozoa. Invertebrata
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Summary:The recently described gutless Astomonema southwardorum Austen, Warwick & Ryan 1993, from North Sea methane seeps lives in symbiosis with oval, extracellular bacteria completely filling the lumen of a modified gut. The bacterial strand is tightly lined by a thin layer representing very long intestinal cells of the host. The bacteria are 5.5–6.0 µm in maximum length and 3.5–4.0 µm in width. In the anterior body the alimentary tract is completely reduced. The structure and size of the symbiotic prokaryotes, as well as their extracellular location in the lumen of a non-functional gut, differ substantially from those in A. jenneri, the single species of this genus thoroughly studied electron-microscopically (Ott et al., 1982). These structural discrepancies suggest a careful reassessment of the genus Astomonema.
ISSN:0025-3154
1469-7769
DOI:10.1017/S0025315400015265