Unbekannt
ELSEVIER SCIENCE BV
In:
EPIC3Journal of Experimental Marine Biology and Ecology, ELSEVIER SCIENCE BV, 424-42, pp. 53-58, ISSN: 0022-0981
Publikationsdatum:
2019-07-17
Beschreibung:
Calcareous foraminifera are well known for their CaCO3 shells. Yet, CaCO3 precipitation acidifies the calcifying
fluid. Calcification without pH regulation would therefore rapidly create a negative feedback for CaCO3 precipitation.
In unicellular organisms, like foraminifera, an effective mechanism to counteract this acidification could
be the externalization of H+ from the site of calcification. In this study we showthat a benthic symbiont-free foraminifer
Ammonia sp. actively decreases pH within its extracellular microenvironment only while precipitating
calcite. During chamber formation events the strongest pH decreases occurred in the vicinity of a newly forming
chamber (range of gradient ~100 μm) with a recorded minimum of 6.31 (b10 μm from the shell) and a maximumduration
of 7 h. The acidification was actively regulated by the foraminifera and correlatedwith shell diameters,
indicating that the amount of protons removed during calcification is directly related to the volume of
calcite precipitated. The here presented findings imply that H+ expulsion as a result of calcification may be a
wider strategy for maintaining pH homeostasis in unicellular calcifying organisms.
Repository-Name:
EPIC Alfred Wegener Institut
Materialart:
Article
,
isiRev
Format:
application/pdf
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