| Autor: |
Breusing C; University of Rhode Island, Graduate School of Oceanography, Narragansett, RI, USA. corinnabreusing@gmail.com., Mitchell J; Harvard University, Department of Organismic and Evolutionary Biology, Cambridge, MA, USA., Delaney J; Harvard University, Department of Organismic and Evolutionary Biology, Cambridge, MA, USA., Sylva SP; Woods Hole Oceanographic Institution, Department of Marine Chemistry and Geochemistry, Woods Hole, MA, USA., Seewald JS; Woods Hole Oceanographic Institution, Department of Marine Chemistry and Geochemistry, Woods Hole, MA, USA., Girguis PR; Harvard University, Department of Organismic and Evolutionary Biology, Cambridge, MA, USA., Beinart RA; University of Rhode Island, Graduate School of Oceanography, Narragansett, RI, USA. |
| Abstrakt: |
Symbioses between invertebrate animals and chemosynthetic bacteria form the basis of hydrothermal vent ecosystems worldwide. In the Lau Basin, deep-sea vent snails of the genus Alviniconcha associate with either Gammaproteobacteria (A. kojimai, A. strummeri) or Campylobacteria (A. boucheti) that use sulfide and/or hydrogen as energy sources. While the A. boucheti host-symbiont combination (holobiont) dominates at vents with higher concentrations of sulfide and hydrogen, the A. kojimai and A. strummeri holobionts are more abundant at sites with lower concentrations of these reductants. We posit that adaptive differences in symbiont physiology and gene regulation might influence the observed niche partitioning between host taxa. To test this hypothesis, we used high-pressure respirometers to measure symbiont metabolic rates and examine changes in gene expression among holobionts exposed to in situ concentrations of hydrogen (H 2 : ~25 µM) or hydrogen sulfide (H 2 S: ~120 µM). The campylobacterial symbiont exhibited the lowest rate of H 2 S oxidation but the highest rate of H 2 oxidation, with fewer transcriptional changes and less carbon fixation relative to the gammaproteobacterial symbionts under each experimental condition. These data reveal potential physiological adaptations among symbiont types, which may account for the observed net differences in metabolic activity and contribute to the observed niche segregation among holobionts. |
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