The relationship between iron and nitrogen fixation in Trichodesmium spp.
Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2009. Includes bibliographical references. Trichodesmium spp. are considere...
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ftmit:oai:dspace.mit.edu:1721.1/53103 2023-06-11T04:14:51+02:00 The relationship between iron and nitrogen fixation in Trichodesmium spp. Chappell, Phoebe Dreux James W. Moffett, John B. Waterbury and Eric A. Webb. Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering Woods Hole Oceanographic Institution Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences 2009 130 p. application/pdf http://hdl.handle.net/1721.1/53103 eng eng Massachusetts Institute of Technology http://hdl.handle.net/1721.1/53103 502997497 M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 /Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering Earth Atmospheric and Planetary Sciences Woods Hole Oceanographic Institution Cyanobacteria Marine productivity Thesis 2009 ftmit 2023-05-29T07:31:46Z Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2009. Includes bibliographical references. 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 (<0.4[mu]m 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. by Phoebe Dreux Chappell. S.M. Thesis North Atlantic DSpace@MIT (Massachusetts Institute of Technology) Pacific Phoebe ENVELOPE(-68.765,-68.765,-71.791,-71.791) |
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DSpace@MIT (Massachusetts Institute of Technology) |
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language |
English |
topic |
/Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering Earth Atmospheric and Planetary Sciences Woods Hole Oceanographic Institution Cyanobacteria Marine productivity |
spellingShingle |
/Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering Earth Atmospheric and Planetary Sciences Woods Hole Oceanographic Institution Cyanobacteria Marine productivity Chappell, Phoebe Dreux The relationship between iron and nitrogen fixation in Trichodesmium spp. |
topic_facet |
/Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering Earth Atmospheric and Planetary Sciences Woods Hole Oceanographic Institution Cyanobacteria Marine productivity |
description |
Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2009. Includes bibliographical references. 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 (<0.4[mu]m 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. by Phoebe Dreux Chappell. S.M. |
author2 |
James W. Moffett, John B. Waterbury and Eric A. Webb. Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering Woods Hole Oceanographic Institution Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
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 |
publishDate |
2009 |
url |
http://hdl.handle.net/1721.1/53103 |
long_lat |
ENVELOPE(-68.765,-68.765,-71.791,-71.791) |
geographic |
Pacific Phoebe |
geographic_facet |
Pacific Phoebe |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
http://hdl.handle.net/1721.1/53103 502997497 |
op_rights |
M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 |
_version_ |
1768371186643763200 |