The relationship between iron and nitrogen fixation in Trichodesmium spp.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2009 Trichodesmium spp. are considered the dominant nitrogen (N) fixing cyanobacteria in tropical and subtropical...
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Massachusetts Institute of Technology and Woods Hole Oceanographic Institution
2009
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ftwhoas:oai:darchive.mblwhoilibrary.org:1912/2971 2023-05-15T17:35:27+02:00 The relationship between iron and nitrogen fixation in Trichodesmium spp. Chappell, Phoebe Dreux Sargasso Sea Equatorial Atlantic Ocean Western Pacific 2009-06 application/pdf https://hdl.handle.net/1912/2971 en_US eng Massachusetts Institute of Technology and Woods Hole Oceanographic Institution WHOI Theses https://hdl.handle.net/1912/2971 doi:10.1575/1912/2971 doi:10.1575/1912/2971 Cyanobacteria Marine productivity Kilo Moana (Ship) Cruise KM0701 Seward Johnson (Ship) Cruise SJ0609 Oceanus (Ship : 1975-) Cruise OC399-4 Thesis 2009 ftwhoas https://doi.org/10.1575/1912/2971 2022-05-28T22:57:46Z Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2009 Trichodesmium spp. are considered the dominant nitrogen (N) fixing cyanobacteria in tropical and subtropical oceans, regimes frequently characterized by low iron (Fe). Limited information exists about what levels of Fe limit Trichodesmium N fixation. I developed a diagnostic for Fe limitation using quantitative reverse transcription PCR (qRT-PCR) of the Fe stress response gene isiB, which encodes for flavodoxin a non-Fe containing substitute for ferredoxin. I determined that high isiB gene expression corresponded to cell-specific reductions in N fixation rates in both phylogenetic clades of Trichodesmium grown on varying levels of Fe. Using these laboratory-determined thresholds, I assessed Fe limitation of Trichodesmium from the Sargasso Sea, equatorial Atlantic Ocean and Western Pacific Warm Pool in conjunction with other analytical measurements (N, phosphorus (P) and dissolved Fe (<0.4μm filtered)). I found widespread Fe limitation in Trichodesmium from the Pacific Ocean and minimal expression in the North Atlantic Ocean. I also found an inverse correlation between isiB expression and dissolved Fe:P ratios in seawater and data suggesting that most dissolved Fe in seawater, including organic ligand-bound Fe, is available to Trichodesmium. These data support and refine previous model predictions and demonstrate, in situ, the importance of Fe to the marine N cycle. Henry Houghton Fund, the Center for BioInorganic Chemistry, the National Science Foundation (grants OCE- 0220945 and OCE-0623499), a National Defense Science and Engineering Graduate Fellowship and the WHOI Academic Programs Office. Thesis North Atlantic Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) Pacific Woods Hole, MA |
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Open Polar |
collection |
Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
op_collection_id |
ftwhoas |
language |
English |
topic |
Cyanobacteria Marine productivity Kilo Moana (Ship) Cruise KM0701 Seward Johnson (Ship) Cruise SJ0609 Oceanus (Ship : 1975-) Cruise OC399-4 |
spellingShingle |
Cyanobacteria Marine productivity Kilo Moana (Ship) Cruise KM0701 Seward Johnson (Ship) Cruise SJ0609 Oceanus (Ship : 1975-) Cruise OC399-4 Chappell, Phoebe Dreux The relationship between iron and nitrogen fixation in Trichodesmium spp. |
topic_facet |
Cyanobacteria Marine productivity Kilo Moana (Ship) Cruise KM0701 Seward Johnson (Ship) Cruise SJ0609 Oceanus (Ship : 1975-) Cruise OC399-4 |
description |
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2009 Trichodesmium spp. are considered the dominant nitrogen (N) fixing cyanobacteria in tropical and subtropical oceans, regimes frequently characterized by low iron (Fe). Limited information exists about what levels of Fe limit Trichodesmium N fixation. I developed a diagnostic for Fe limitation using quantitative reverse transcription PCR (qRT-PCR) of the Fe stress response gene isiB, which encodes for flavodoxin a non-Fe containing substitute for ferredoxin. I determined that high isiB gene expression corresponded to cell-specific reductions in N fixation rates in both phylogenetic clades of Trichodesmium grown on varying levels of Fe. Using these laboratory-determined thresholds, I assessed Fe limitation of Trichodesmium from the Sargasso Sea, equatorial Atlantic Ocean and Western Pacific Warm Pool in conjunction with other analytical measurements (N, phosphorus (P) and dissolved Fe (<0.4μm filtered)). I found widespread Fe limitation in Trichodesmium from the Pacific Ocean and minimal expression in the North Atlantic Ocean. I also found an inverse correlation between isiB expression and dissolved Fe:P ratios in seawater and data suggesting that most dissolved Fe in seawater, including organic ligand-bound Fe, is available to Trichodesmium. These data support and refine previous model predictions and demonstrate, in situ, the importance of Fe to the marine N cycle. Henry Houghton Fund, the Center for BioInorganic Chemistry, the National Science Foundation (grants OCE- 0220945 and OCE-0623499), a National Defense Science and Engineering Graduate Fellowship and the WHOI Academic Programs Office. |
format |
Thesis |
author |
Chappell, Phoebe Dreux |
author_facet |
Chappell, Phoebe Dreux |
author_sort |
Chappell, Phoebe Dreux |
title |
The relationship between iron and nitrogen fixation in Trichodesmium spp. |
title_short |
The relationship between iron and nitrogen fixation in Trichodesmium spp. |
title_full |
The relationship between iron and nitrogen fixation in Trichodesmium spp. |
title_fullStr |
The relationship between iron and nitrogen fixation in Trichodesmium spp. |
title_full_unstemmed |
The relationship between iron and nitrogen fixation in Trichodesmium spp. |
title_sort |
relationship between iron and nitrogen fixation in trichodesmium spp. |
publisher |
Massachusetts Institute of Technology and Woods Hole Oceanographic Institution |
publishDate |
2009 |
url |
https://hdl.handle.net/1912/2971 |
op_coverage |
Sargasso Sea Equatorial Atlantic Ocean Western Pacific |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
doi:10.1575/1912/2971 |
op_relation |
WHOI Theses https://hdl.handle.net/1912/2971 doi:10.1575/1912/2971 |
op_doi |
https://doi.org/10.1575/1912/2971 |
op_publisher_place |
Woods Hole, MA |
_version_ |
1766134629502287872 |