Beinart Roxanne A.

No Thumbnail Available
Last Name
Beinart
First Name
Roxanne A.
ORCID

Filters

2012 - 2020 4
4
4
Reset filters

Settings

Search Results

Now showing 1 - 4 of 4
  • Article
    Links from mantle to microbe at the Lau Integrated Study Site : insights from a back-arc spreading center
    (The Oceanography Society, 2012-03) Tivey, Margaret K. ; Becker, Erin ; Beinart, Roxanne A. ; Fisher, Charles R. ; Girguis, Peter R. ; Langmuir, Charles H. ; Michael, Peter J. ; Reysenbach, Anna-Louise
    The Lau Integrated Study Site (ISS) has provided unique opportunities for study of ridge processes because of its back-arc setting in the southwestern Pacific. Its location allows study of a biogeographical province distinct from those of eastern Pacific and mid-Atlantic ridges, and crustal compositions along the ridge lie outside the range of mid-ocean ridge crustal compositions. The Lau ISS is located above a subduction zone, at an oblique angle. The underlying mantle receives water and other elements derived from the downgoing lithospheric slab, with an increase in slab influence from north to south. Water lowers the mantle melting temperature and leads to greater melt production where the water flux is greater, and to distinctive regional-scale gradients along the ridge. There are deeper faulted axial valleys with basaltic volcanism in the north and inflated axial highs with andesites in the south. Differences in igneous rock composition and release of magmatic volatiles affect compositions of vent fluids and deposits. Differences in vent fluid compositions and small-scale diffuse-flow regimes correlate with regional-scale patterns in microbial and megafaunal distributions. The interdisciplinary research effort at the Lau ISS has successfully identified linkages between subsurface processes and deep-sea biological communities, from mantle to microbe to megafauna.
  • Article
    Exploration of the Northern Guaymas Basin
    (The Oceanography Society, 2018-03) Soule, Samuel A. ; Seewald, Jeffrey S. ; Wankel, Scott D. ; Michel, Anna P. M. ; Beinart, Roxanne A. ; Escobar Briones, Elva ; Morales Dominguez, Esmerelda ; Girguis, Peter R. ; Coleman, Dwight ; Raineault, Nicole A. ; Wagner, Jamie K.S. ; Foulk, Aubrey ; Bagla, Anshika ; Karson, Jeffrey A.
  • 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
    Metatranscriptional response of chemoautotrophic Ifremeria nautilei endosymbionts to differing sulfur regimes
    (Frontiers Media, 2016-07-19) Seston, Sherry L. ; Beinart, Roxanne A. ; Sarode, Neha ; Shockey, Abigail C. ; Ranjan, Piyush ; Ganesh, Sangita ; Girguis, Peter R. ; Stewart, Frank J.
    Endosymbioses between animals and chemoautotrophic bacteria are ubiquitous at hydrothermal vents. These environments are distinguished by high physico-chemical variability, yet we know little about how these symbioses respond to environmental fluctuations. We therefore examined how the γ-proteobacterial symbionts of the vent snail Ifremeria nautilei respond to changes in sulfur geochemistry. Via shipboard high-pressure incubations, we subjected snails to 105 μM hydrogen sulfide (LS), 350 μM hydrogen sulfide (HS), 300 μM thiosulfate (TS) and seawater without any added inorganic electron donor (ND). While transcript levels of sulfur oxidation genes were largely consistent across treatments, HS and TS treatments stimulated genes for denitrification, nitrogen assimilation, and CO2 fixation, coincident with previously reported enhanced rates of inorganic carbon incorporation and sulfur oxidation in these treatments. Transcripts for genes mediating oxidative damage were enriched in the ND and LS treatments, potentially due to a reduction in O2 scavenging when electron donors were scarce. Oxidative TCA cycle gene transcripts were also more abundant in ND and LS treatments, suggesting that I. nautilei symbionts may be mixotrophic when inorganic electron donors are limiting. These data reveal the extent to which I. nautilei symbionts respond to changes in sulfur concentration and species, and, interpreted alongside coupled biochemical metabolic rates, identify gene targets whose expression patterns may be predictive of holobiont physiology in environmental samples.