Changes in ultrastructural features of the foraminifera Ammonia spp. in response to anoxic conditions: Field and laboratory observations

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TitreChanges in ultrastructural features of the foraminifera Ammonia spp. in response to anoxic conditions: Field and laboratory observations
Type de publicationArticle de revue
AuteurKoho, Karoliina Annika, Lekieffre, Charlotte , Nomaki, Hidetaka, Salonen, I., Geslin, Emmanuelle , Mabilleau, Guillaume , Søgaard Jensen, Louise Helene, Reichart, Gert-Jan
EditeurElsevier
TypeArticle scientifique dans une revue à comité de lecture
Année2018
LangueAnglais
DateJanvier 2018
Pagination72-82
Volume138
Titre de la revueMarine Micropaleontology
ISSN03778398
Mots-clésAnoxia, Bacteria, benthic foraminifera, lipid droplets, Ultrastructure
Résumé en anglais

The ultrastructure of the living foraminiferan, Ammonia sp. (phylotype unknown), collected from surficial and deeper, subsurface (anoxic) sediments from the Dutch Wadden Sea, was examined to provide information on the physiology of the foraminiferal cell and its adaptive strategies to low‑oxygen conditions. The observed changes in cell ultrastructure under anoxia were further compared with the cell ultrastructure of Ammonia sp. (phylotype T6), from oxic and anoxic incubation experiments. The ultrastructural evidence indicates that under low‑oxygen conditions Ammonia spp. may accumulate lipid droplets. In addition, the size of the lipid droplets may increase with the duration of anoxic conditions, becoming over 5 μm in size, while the remaining cytosol of the foraminiferan become less electron dense. In some specimens, lipid droplets were also found in the space between the plasma membrane and the organic lining. We expect that the apparent increase in the number and size of the lipid droplets is indicative of a stress response of the foraminifera to the adverse anoxic conditions. Other ultrastructural changes in response to anoxia include the presence of intact bacteria and electron dense opaque bodies within the foraminiferal cytosol, and a possible thickening of the organic lining. The role of the bacteria remains enigmatic but they may be linked to foraminiferal dormancy in anoxia.

URL de la noticehttp://okina.univ-angers.fr/publications/ua18565
DOI10.1016/j.marmicro.2017.10.011
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https://www.sciencedirect.com/science/article/pii/S0377839817300385?via%...

Titre abrégéMar. micropaleontol.