Evidence for nitrate uptake mechanism in the hydrothermal vent tube-worm Riftia pachyptila
Hentschel, U.; Pospesel, M.A.; Felbeck, H. (1998). Evidence for nitrate uptake mechanism in the hydrothermal vent tube-worm Riftia pachyptila. Cah. Biol. Mar. 39(3-4): 301-304. https://dx.doi.org/10.21411/CBM.A.F6C719A0
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723; e-ISSN 2262-3094, more
Also appears in:(1998). Proceedings of the First International Symposium on Deep-Sea Hydrothermal Vent Biology: Funchal, Madeira, Portugal 20-24 October 1997. Cahiers de Biologie Marine, 39(3-4). Station Biologique de Roscoff: Roscoff. 219-392 pp., more
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| Authors | | Top |
- Hentschel, U.
- Pospesel, M.A.
- Felbeck, H.
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| Abstract |
The vestimentiferan tube worm Riftia pachyptila Jones, 1981 is found around hydrothermal vent areas in the deep sea. Intracellular bacterial chemoautotrophic symbionts use the oxidation of sulphide from the effluent of the vents as an energy source for CO2 fixation (Nelson & Fisher, 1995). They apparently provide most or all of the nutritional requirements for their gutless hosts. A closed vascular system circulates haemoglobin containing blood and provides a vehicle for the transport of metabolites between the environment and the symbiotic bacteria. The trophosome, the internal organ harbouring the symbionts, is bathed in a coelomic fluid which also contains haemoglobin. While the host respires oxygen in a heterotrophic metabolism, the bacteria require sulphide, CO2 and an oxidant for their autotrophic metabolism. We present results that the symbiotic bacteria of R. pachyptila are capable of respiring nitrate and nitrite in addition to oxygen. Moreover, the vascular blood of Riftia pachyptila was shown to have nitrate concentrations of up to one hundred times that of ambient seawater. Blood nitrate levels reached concentrations of >1 mM with a maximum value of 4.5 mM, while nitrite was measured in the range of 400-700 mu M with a maximum value of 2.2 mM. The concentrations of nitrate and nitrite in the coelomic fluids were 150-240 mu M and < 20 mu M respectively. |
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