Search

Strontium‐rich micropearls (intracellular inclusions of amorphous calcium carbonate) have been observed in several species of green microalgae within the class Chlorodendrophyceae, suggesting the potential use of these organisms for 90Sr bioremediation purposes. However, very little is known about the micropearl formation process and the Ca and Sr uptake dynamics of these microalgae. To better understand this phenomenon, we investigated, through laboratory cultures, the behaviour of two species within the class Chorodendrophyceae: Tetraselmis chui, forming micropearls, and T. marina, not forming micropearls. We show that T. chui growth and micropearl formation requires available Ca in the culture medium, and that the addition of dissolved Sr can partially replace the function of Ca in cells. On the other hand, T. marina can grow without added Ca and Sr, probably due to its inability to form micropearls. T. chui cells show a high Ca and Sr uptake, significantly decreasing the concentration of both elements in the culture medium. Strontium is incorporated in micropearls in a short period of time, suggesting that micropearl formation is, most likely, a fast process that only takes a few hours. In addition, we show that micropearls equally distribute between daughter cells during cell division. [ABSTRACT FROM AUTHOR]

Summary: An unsuspected biomineralization process, which produces intracellular inclusions of amorphous calcium carbonate (ACC), was recently discovered in unicellular eukaryotes. These mineral inclusions, called micropearls, can be highly enriched with other alkaline‐earth metals (AEM) such as Sr and Ba. Similar intracellular inclusions of ACC have also been observed in prokaryotic organisms. These comparable biomineralization processes involving phylogenetically distant microorganisms are not entirely understood yet. This review gives a broad vision of the topic in order to establish a basis for discussion on the possible molecular processes behind the formation of the inclusions, their physiological role, the impact of these microorganisms on the geochemical cycles of AEM and their evolutionary relationship. Finally, some insights are provided to guide future research. [ABSTRACT FROM AUTHOR]

This article explores the interactions between the diatom Cyclotella meneghiniana and citrate-coated silver nanoparticles (Cit-AgNPs). The study aims to understand the response of diatoms to AgNP exposure and the underlying mechanisms involved. The research found that both Cit-AgNPs and dissolved Ag+ had negative effects on diatom growth, membrane permeability, photosynthesis, and morphology. However, the toxicity of Ag+ was found to be higher than that of Cit-AgNPs. The study also observed increased levels of proline accumulation and the presence of polyphosphate bodies in response to metal toxicity and stress. Overall, the research suggests that C. meneghiniana adopts synergistic mechanisms to cope with toxic levels of silver in both nanoparticulate and ionic forms. [Extracted from the article]