Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that i...
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ftpubmed:oai:pubmedcentral.nih.gov:7329048 2023-05-15T18:01:02+02:00 Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts LeKieffre, Charlotte Spero, Howard J. Fehrenbacher, Jennifer S. Russell, Ann D. Ren, Haojia Geslin, Emmanuelle Meibom, Anders 2020-06-24 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7329048/ http://www.ncbi.nlm.nih.gov/pubmed/32546098 https://doi.org/10.1098/rspb.2020.0620 en eng The Royal Society http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7329048/ http://www.ncbi.nlm.nih.gov/pubmed/32546098 http://dx.doi.org/10.1098/rspb.2020.0620 © 2020 The Authors. http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/http://creativecommons.org/licenses/by/4.0/Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. CC-BY Proc Biol Sci Palaeobiology Text 2020 ftpubmed https://doi.org/10.1098/rspb.2020.0620 2020-07-05T01:04:36Z The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk (15)N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with (13)C-enriched inorganic carbon, (15)N-nitrate, and (15)N-ammonium, as well as a (13)C- and (15)N- enriched heterotrophic food source, followed by TEM (transmission electron microscopy) coupled to NanoSIMS (nanoscale secondary ion mass spectrometry) isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of (15)N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with (15)N-ammonium, indicating efficient ammonium assimilation. Only weak (15)N-assimilation was observed after incubation with (15)N-nitrate. Feeding foraminifers with (13)C- and (15)N-labelled food resulted in dinoflagellates that were labelled with (15)N, thereby confirming the transfer of (15)N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based palaeoceanographic reconstructions, as they show that δ(15)N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates. Text Planktonic foraminifera PubMed Central (PMC) Proceedings of the Royal Society B: Biological Sciences 287 1929 20200620 |
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Palaeobiology |
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Palaeobiology LeKieffre, Charlotte Spero, Howard J. Fehrenbacher, Jennifer S. Russell, Ann D. Ren, Haojia Geslin, Emmanuelle Meibom, Anders Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts |
topic_facet |
Palaeobiology |
description |
The symbiotic planktonic foraminifera Orbulina universa inhabits open ocean oligotrophic ecosystems where dissolved nutrients are scarce and often limit biological productivity. It has previously been proposed that O. universa meets its nitrogen (N) requirements by preying on zooplankton, and that its symbiotic dinoflagellates recycle metabolic ‘waste ammonium’ for their N pool. However, these conclusions were derived from bulk (15)N-enrichment experiments and model calculations, and our understanding of N assimilation and exchange between the foraminifer host cell and its symbiotic dinoflagellates remains poorly constrained. Here, we present data from pulse-chase experiments with (13)C-enriched inorganic carbon, (15)N-nitrate, and (15)N-ammonium, as well as a (13)C- and (15)N- enriched heterotrophic food source, followed by TEM (transmission electron microscopy) coupled to NanoSIMS (nanoscale secondary ion mass spectrometry) isotopic imaging to visualize and quantify C and N assimilation and translocation in the symbiotic system. High levels of (15)N-labelling were observed in the dinoflagellates and in foraminiferal organelles and cytoplasm after incubation with (15)N-ammonium, indicating efficient ammonium assimilation. Only weak (15)N-assimilation was observed after incubation with (15)N-nitrate. Feeding foraminifers with (13)C- and (15)N-labelled food resulted in dinoflagellates that were labelled with (15)N, thereby confirming the transfer of (15)N-compounds from the digestive vacuoles of the foraminifer to the symbiotic dinoflagellates, likely through recycling of ammonium. These observations are important for N isotope-based palaeoceanographic reconstructions, as they show that δ(15)N values recorded in the organic matrix in symbiotic species likely reflect ammonium recycling rather than alternative N sources, such as nitrates. |
format |
Text |
author |
LeKieffre, Charlotte Spero, Howard J. Fehrenbacher, Jennifer S. Russell, Ann D. Ren, Haojia Geslin, Emmanuelle Meibom, Anders |
author_facet |
LeKieffre, Charlotte Spero, Howard J. Fehrenbacher, Jennifer S. Russell, Ann D. Ren, Haojia Geslin, Emmanuelle Meibom, Anders |
author_sort |
LeKieffre, Charlotte |
title |
Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts |
title_short |
Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts |
title_full |
Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts |
title_fullStr |
Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts |
title_full_unstemmed |
Ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts |
title_sort |
ammonium is the preferred source of nitrogen for planktonic foraminifer and their dinoflagellate symbionts |
publisher |
The Royal Society |
publishDate |
2020 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7329048/ http://www.ncbi.nlm.nih.gov/pubmed/32546098 https://doi.org/10.1098/rspb.2020.0620 |
genre |
Planktonic foraminifera |
genre_facet |
Planktonic foraminifera |
op_source |
Proc Biol Sci |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7329048/ http://www.ncbi.nlm.nih.gov/pubmed/32546098 http://dx.doi.org/10.1098/rspb.2020.0620 |
op_rights |
© 2020 The Authors. http://creativecommons.org/licenses/by/4.0/ http://creativecommons.org/licenses/by/4.0/http://creativecommons.org/licenses/by/4.0/Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1098/rspb.2020.0620 |
container_title |
Proceedings of the Royal Society B: Biological Sciences |
container_volume |
287 |
container_issue |
1929 |
container_start_page |
20200620 |
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1766170358954590208 |