Sökning: "Rachel A. Foster"

Hittade 5 avhandlingar innehållade orden Rachel A. Foster.

  1. 1. Significance of N2 fixing planktonic symbioses for open ocean ecosystems

    Författare :Marcus Stenegren; Rachel A. Foster; Agneta Andersson; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; nitrogen fixation; diazotrophs; symbiosis; DDA; cyanobacteria; qPCR; piecewise SEM; microarray; tropics; subtropics; marine; open ocean; Richelia; Calothrix; Marine Ecology; marin ekologi;

    Sammanfattning : Di-nitrogen (N2) fixers, also called diazotrophs, are able to reduce atmospheric N2 into bioavailable nitrogen, giving them an advantage in open ocean regions with low dissolved inorganic nitrogen concentrations. The focus of this thesis are three lineages of symbiotic heterocystous filamentous types (het-1, het-2 and het-3), that associate with several genera of microalgae called diatoms (collectively referred to as Diatom Diazotroph Associations, DDAs). LÄS MER

  3. 2. Factors influencing emission fluxes and bacterial enrichment in sea spray aerosols : Insights from laboratory and field studies

    Författare :Julika Zinke; Matthew E. Salter; Paul Zieger; Rachel A. Foster; E. Douglas Nilsson; Patricia K. Quinn; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Sea spray aerosols; eddy covariance fluxes; air-sea-exchange; bacteria; primary biological airborne particles; laboratory studies; field studies; Baltic Sea; North-Eastern Atlantic; Environmental Sciences; miljövetenskap;

    Sammanfattning : Sea spray aerosol (SSA) is one of the major natural aerosol sources and is produced when wave breaking entrains air into ocean surface water, which subsequently breaks up into bubbles. These bubbles rise to the surface and can scavenge biogenic material. LÄS MER

  4. 3. Genomic and morphological diversity of marine planktonic diatom-diazotroph associations : a continuum of integration and diversification through geological time

    Författare :Andrea Caputo; Rachel Ann Foster; Monika Quinones Winder; Ramon Massana; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; phytoplankton; diatoms; cyanobacteria; diazotrophs; symbiosis; evolution; phylogenetics; confocal microscopy; qPCR; CARD-FISH; tropics; sub-tropics; Marine Ecology; marin ekologi;

    Sammanfattning : Symbioses between eukaryotes and nitrogen (N2)-fixing cyanobacteria (or diazotrophs) are quite common in the plankton community. A few genera of diatoms (Bacillariophyceae) such as Rhizosolenia, Hemiaulus and Chaetoceros are well known to form symbioses with the heterocystous diazotrophic cyanobacteria Richelia intracellularis and Calothrix rhizosoleniae. LÄS MER

  5. 4. Molecular detection of abundance and activity of marine, symbiotic, N2-fixing cyanobacteria

    Författare :Linnéa Ström; Rachel Foster; Daniel Lundin; Katharina Pawlowski; Rehab El-Shehawy; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Diatom Diazotroph Association; Richelia; Iron; Phosphorus; Nitrogen; nifH; pstS; exbB; rnpA; växtfysiologi; Plant Physiology; marinbiologi; Marine Biology;

    Sammanfattning : Marine primary productivity in large parts of the oceans is supported by nitrogen fixers (diazotrophs). Richelia, a genus of multiple closely related species of heterocystous filamentous cyanobacterial diazotrophs, are often found in symbioses with a few genera of diatoms. Several Richelia species: R. euintracellularis, R. LÄS MER

  7. 5. Environmental conditions governing the distributions of symbiotic and free-living diazotrophic cyanobacteria in two tropical open oceans

    Författare :Marcus Stenegren; Rachel Foster; Bethany Jenkins; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Nitrogen fixation; Diazotroph; Cyanobacteria; Symbiosis; DDA; Richelia; Marine Ecology; marin ekologi;

    Sammanfattning : Di-nitrogen (N2) fixation plays a crucial role in oceanic carbon and nitrogen cycles and is important for marine biogeochemistry on regional and global scales. N2-fixing (diazotrophs) cyanobacteria are considered to contribute the most to marine nitrogen fixation, and thereby fuel the surrounding phytoplankton communities with bioavailable ammonia. LÄS MER