Mitchell Jessica

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Mitchell
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Jessica
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  • Article
    Physiological dynamics of chemosynthetic symbionts in hydrothermal vent snails
    (Springer Nature, 2020-07-02) Breusing, Corinna ; Mitchell, Jessica ; Delaney, Jennifer ; Sylva, Sean P. ; Seewald, Jeffrey S. ; Girguis, Peter R. ; Beinart, Roxanne A.
    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 (H2: ~25 µM) or hydrogen sulfide (H2S: ~120 µM). The campylobacterial symbiont exhibited the lowest rate of H2S oxidation but the highest rate of H2 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.
  • Article
    Animal life in the shallow subseafloor crust at deep-sea hydrothermal vent
    (Nature Research, 2024-10-15) Bright, Monika ; Gollner, Sabine ; de Oliveira, André Luiz ; Espada-Hinojosa, Salvador ; Fulford, Avery ; Hughes, Ian Vincent ; Hourdez, Stephane ; Karthäuser, Clarissa ; Kolar, Ingrid ; Krause, Nicole ; Le Layec, Victor ; Makovec, Tihomir ; Messora, Alessandro ; Mitchell, Jessica ; Pröts, Phillipp ; Rodríguez-Ramírez, Ivonne ; Sieler, Fanny ; Sievert, Stefan M. ; Steger, Jan ; Tinta, Tinkara ; Winter, Teresa Rosa Maria ; Bright, Zach ; Coffield, Russel ; Hill, Carl ; Ingram, Kris ; Paris, Alex
    It was once believed that only microbes and viruses inhabited the subseafloor crust beneath hydrothermal vents. Yet, on the seafloor, animals like the giant tubeworm Riftia pachyptila thrive. Their larvae are thought to disperse in the water column, despite never being observed there. We hypothesized that these larvae travel through the subseafloor via vent fluids. In our exploration, lifting lobate lava shelves revealed adult tubeworms and other vent animals in subseafloor cavities. The discovery of vent endemic animals below the visible seafloor shows that the seafloor and subseafloor faunal communities are connected. The presence of adult tubeworms suggests larval dispersal through the recharge zone of the hydrothermal circulation system. Given that many of these animals are host to dense bacterial communities that oxidize reduced chemicals and fix carbon, the extension of animal habitats into the subseafloor has implications for local and regional geochemical flux measurements. These findings underscore the need for protecting vents, as the extent of these habitats has yet to be fully ascertained.