Crystalline guanine: Rediscovery of a long- overlooked structure of unicellular eukaryotes

Abstract

Photosynthetic microorganisms living freely in aquatic environments must cope with the variable availability of essential nutrients, particularly nitrogen, phosphorus, and iron. It is not surprising that during evolution, various mechanisms have developed for the accumulation and storage of these elements in suitable reserve forms, which are created during periods of element availability, so that they can be used during periods of their scarcity. Some storage structures in some organisms were identified and studied decades ago, while others were discovered only recently, although their presence has been noted and well-documented for a long time. They remained an overlooked structure until their chemical composition was elucidated.