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| Titel |
Flow cytometric assessment of specific leucine incorporation in the open Mediterranean |
| VerfasserIn |
A. Talarmin, F. Wambeke, P. Catala, C. Courties, P. Lebaron |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 2 ; Nr. 8, no. 2 (2011-02-07), S.253-265 |
| Datensatznummer |
250005439
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| Publikation (Nr.) |
 copernicus.org/bg-8-253-2011.pdf |
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| Zusammenfassung |
| The surface of the Mediterranean Sea is a low-phosphate-low-chlorophyll
marine area where marine heterotrophic prokaryotes significantly contribute
to the biogeochemical cycles of all biogenic elements such as carbon,
notably through the mineralization of dissolved organic compounds.
Cell-specific leucine incorporation rates were determined in early summer in
the open stratified Mediterranean Sea. The bulk leucine incorporation rate
was on average 5 ± 4 pmol leu l−1 h−1 (n=30). Cell-specific
3H-leucine incorporation rates were assayed using flow cytometry
coupled to cell sorting. Heterotrophic prokaryotes (Hprok) were divided into
cytometric groups according to their side scatter and green fluorescence
properties: high nucleic acid containing cells (HNA) with high scatter
(HNA-hs) and low scatter (HNA-ls) and low nucleic acid containing cells
(LNA). Cell-specific leucine incorporation rates of these cytometric groups
ranged from 2 to 54, 0.9 to 11, and 1 to 12 × 10-21 mol cell−1 h−1, respectively.
LNA cells represented 45 to 63% of the Hprok
abundance, and significantly contributed to the bulk leucine incorporation
rates, from 12 to 43%. HNA/LNA ratios of cell-specific leucine
incorporation were on average 2.0 ± 0.7 (n=30). In surface layers (from
0 m down to the deep chlorophyll depth, DCM), cell-specific rates of HNA-hs
were elevated (7 and 13 times greater than LNA and HNA-ls, respectively).
Nevertheless, on average HNA-hs (26%) and LNA (27%) equally
contributed to the bulk leucine incorporation in these layers.
Prochlorococcus cells were easily sorted near the DCM and displayed cell-specific leucine
incorporation rates ranging from 3 to 55 × 10-21 mol leu cell−1 h−1,
i.e. as high as HNA-hs'. These sorted groups could therefore be
defined as key-players in the process of leucine incorporation into
proteins. The mixotrophic features of certain photosynthetic prokaryotes and
the high contribution of LNA cells to leucine incorporation within the
microbial communities of the Mediterranean could be reinforced. |
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