Girguis, P. R. University of California Santa Barbara, girguis@lifesci.ucsb.edu
Childress, J. R. University of California Santa Barbara, childres@lifesci.ucsb.edu

 
METABOLITE FLUX OF THE HYDROTHERMAL VENT TUBEWORM RIFTIA PACHYPTILA: A MODEL OF EXTREME ADAPTATIONS
 
The major constituent of the hydrothermal vent communities along the East Pacific rise is the tubeworm Riftia pachyptila. This worm dominates a unique environment, the region of vent and bottom water mixing at hydrothermal vents. Lacking a digestive tract, Riftia pachyptila lives in association with chemolithoautotrophic bacteria, which it relies upon to fulfill its nutritive requirements. In turn, it must provide its symbionts with the substrates necessary for chemolithoautotrophy, e.g. inorganic carbon, hydrogen sulfide, oxygen and nitrate. Respirometric and other experiments on Riftia pachyptila have revealed a suite of host physiological adaptations to this association. Substantial carbonic anhydrase activity (723 delta pH min-1 g-1) and an unprecedented rate of proton equivalent elimination (119 microeq/g/hr) sustain a net inorganic carbon acquisition while maintaining host acid-base balance. In addition, the host assimilates nitrate, which is reduced by the symbionts at rates which may be sufficient to meet the nitrogen needs of the association (3.78 micromolar/g/hr). These processes do not only reflect adaptation to a symbiotic lifestyle, but also to the temporally variable conditions of its environment.
 
Day: Tuesday, Feb. 2
Time: 11:30 - 11:45am
Location: Sweeney Center
 
Code: SS27TU1145S