Metallic bioaccumulation and sulphur metabolism in the trophosome of Riftia pachyptila and Tevnia jerichonana
Ballan-Dufrançais, Ch.; Jeantet, A.Y.; Truchet, M.; Lechaire, J.-P.; Cosson, R.P.; Gaill, F. (1997). Metallic bioaccumulation and sulphur metabolism in the trophosome of Riftia pachyptila and Tevnia jerichonana, in: Biologie des sources hydrothermales profondes = Biology of deep-sea hydrothermal vents: Journées d'échanges du Programme DORSALES = DORSALES Workshop Roscoff 6-8 octobre 1997. Cahiers de Biologie Marine, 38(2): pp. 113
In: (1997). Biologie des sources hydrothermales profondes = Biology of deep-sea hydrothermal vents: Journées d'échanges du Programme DORSALES = DORSALES Workshop Roscoff 6-8 octobre 1997. Cahiers de Biologie Marine, 38(2)[s.n.][s.l.]. 111-149 pp., more
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723; e-ISSN 2262-3094, more
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| Authors | | Top |
- Ballan-Dufrançais, Ch.
- Jeantet, A.Y.
- Truchet, M.
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- Lechaire, J.-P.
- Cosson, R.P.
- Gaill, F.
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| Abstract |
The vestimetiferan trophosome is hosting symbiotic chemosynthetic sulphur oxidizing bacteria (Childress, 1995). This thermodynamical process is different from the photosynthetic one and has been precisely studied in some microorganisms such as Thiobacillus or Chromatium (Hageage et al., 1970; Nelson-& Hagen, 1995). The biochemical process used by the Riftia pachyptila associated bacteria are still poorly known. It is thought that the sulphur precipitates in S degree elemental form, with an unknown location. Otherwise, the abundance of metallic sulphur in the hydrothermal environment can be considered as an agressive stress leading to development of defense mechanisms. The trophosome which is a site of intense metabolism could be a potential site of metallic detoxification. In order to solve this question, several microscopic methods were used to study the trophosome samples from juvenile and mature vestimentiferan (Riftia pachyptila or Tevnia jerichonana). These samples were collected during 3 french american cruises including Hot 1996. The bacteriocytes display a small number of lysosomes containing Mg, P, S, Ca, Fe, Zn, Cu and Ag. These elements are usually found inside the bacteria. Silver was detected for the first time inside the microorganisms. Their low level content would result from storage excretion of metallic coenzyme or catabolized metallothioneins as in other invertebrates (Jeantet et al., 1997). The vestimentiferan trophosome does not appear to be the bioaccumulation site of the metallic concentrations previously mentioned, In both species, ultrastructural observations do not show intracellular particulate sulphur storage. The disappearance f the crystalline form of sulphur after a specific chemical fixative treatment would indicate the high trophosome sulphur lability. We assume that the elemental sulphur would precipitate into S sub(8) octahedral structures (Pascal, 1960) whose size would be unobservable at the microscopic scale inside the bacteria hyaloplasm. This phenomenon increases with time and octahedral crystals would form larger structures in older bacteria. |
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