Abstrakt
Vast areas of the oceans are N limited, and how microalgae can flourish in these N-poor waters is still not known. Furthermore, mechanisms and sites of N uptake and storage have not been fully determined.
We show that crystalline guanine (C5H5N5O) is an important N storage form for phytoplankton and for symbiotic dinoflagellates of corals. The widespread occurrence of guanine reserves among taxonomically distant microalgal species suggests an early evolutionary origin of its function as N storage.
Crystalline guanine appears to be a multifunctional biochemical with an important role in the N cycle that remains to be elucidated. In particular, a better knowledge of N-storage metabolism is necessary to understand the impact of eutrophication on coral-symbiont interaction.