Avancerad sökning
Hittade 4 avhandlingar som matchar ovanstående sökkriterier.
1. Towards an understanding of diazocyte development and diazotrophy in the marine cyanobacterium Trichodesmium
Sammanfattning : Trichodesmium is a filamentous cyanobacterium of great ecological significance as it contributes significantly to primary production in oceans through an efficient nitrogen fixation strategy, including a unique cell type, the diazocyte. The aim of this thesis was to generate a deeper understanding of the structural and molecular background related to the development of diazocytes and the maintenance of diazotrophy in Trichodesmium erythraeum IMS101. LÄS MER
2. Significance of N2 fixing planktonic symbioses for open ocean ecosystems
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. Nutrient dynamics in the North Pacific subtropical gyre : phosphorus fluxes in the upper oligotrophic ocean
Sammanfattning : In the contemporary North Pacific subtropical gyre (NPSG) the extant microbial community is based on prokaryotic cells with the cyanobacterium Prochlorococcus dominating the phototrophic component. The prevalence of dinitrogen (N2) fixing organisms, such as Trichodesmium spp. LÄS MER
4. Genomic and morphological diversity of marine planktonic diatom-diazotroph associations : a continuum of integration and diversification through geological time
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