An abundant haem protein in Riftia pachyptila symbionts is a nitrite reductase
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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| Abstract |
A large proportion of the biomass at hydrothermal vents is made up of the tube-worm species Riftia pachyptila Jones, 1981. R. pachyptila relies exclusively on its chemosynthetic bacterial symbionts for its source of organic carbon. The symbionts live in an organ, inside the worm, connected to the surrounding seawater only via the worm's closed circulatory system. This symbiont association takes place, of necessity, in a zone exposed alternately to hypoxic, sulphide-rich waters and oxic, sulphide-poor, nitrate-rich waters (see reviews by Nelson & Fisher (1995) and Childress & Fisher (1992) for discussions of the biological aspects of hydrothermal vents and Riftia pachyptila). It is not fully understood how R. pachyptila and it symbiont survive the frequent periods of anoxia they must encounter. Riftia pachyptila symbionts have been shown to respire both oxygen and nitrate. R. pachyptila itself contains widely variable levels of nitrite, potentially a product of nitrate respiration, in its blood stream. Thus, it is possible that R. pachyptila's symbiont may utilize nitrite respiration as well as nitrate respiration in order to survive extended periods of anoxia. In the following paper we present a description of the purification of a nitrite reductase (NR) from R. pachyptila (RpNR). It is not known whether or not this RPNR is assimilatory or dissimilatory. We hope that future experiments by others will determine the role of this abundant protein in the metabolism of R. pachyptila. |
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