Biology subjects

Triccas, A.

Publications and source records attributed to Triccas, A..

3 recordsLinked to original sources

bioRxiv2026

Nanoscale chemical tomography reveals organic and inorganic clusters in fossilised dinosaur tooth

Mineralized dental tissues are formed through biomineralization processes involving the growth and self-organisation of hydroxylapatite (HAP) nanoscale grains. There remain open questions regarding the way elements such as Mg or Na are incorporated in the organic matter between HAP grains or within the grain structure where they influence the nucleation and growth of HAP. Here, mapping the enamel structure and composition of a well-preserved ca. 150-million-year-old Giraffatitan brancai sauropod dinosaur tooth from millimeters down to the near-atomic scale, we reveal the nanoscale accumulation of Mg at HAP grain boundaries, alongside F arising from diagenesis. Within the HAP grains and at HAP grain boundaries organic matter forms clusters that we propose contribute to the fast growth rate of the tooth. Moreover, unexpected Cu3As particles are found across the entire enamel structure. These elements are not in the dentine, that exhibits empty tubules, which suggests that they were integrated during the tooth growth itself. Our multiscale analysis provides new information encouraging to reconsider aspects of the biomineralization and fossilization processes.

paleontology↗

bioRxiv2026

Deciphering Coccolith Formation: Advanced Microscopy Insights from the Biomineralisation of Gephyrocapsa huxleyi

Coccolithophores are unicellular marine phytoplankton that produce complex and intricately shaped mineralised scales called coccoliths. Coccoliths are produced in an intracellular vesicle where crystal nucleation occurs, from which several individual calcite units develop with anisotropic crystallographic facets, prompting studies into the cellular mechanisms which control crystal growth within the cell. Here, we characterise those morphological developments in 3D that occur during the formation of coccoliths by the species Gephyrocapsa huxleyi using cryo-ptychographic X-ray computed tomography. This technique is ideally suited to study coccolith mineral development, as intracellular structures can be imaged intact in their native state without needing to disrupt cells. Combined with additional imaging of developing coccoliths using cryo-transmission electron microscopy and scanning electron microscopy, we report the developmental stages involved in coccolith growth across the complete mineralisation period, while also showing that the constrained space created by individual crystal units growing in close confinement affects the final crystal morphology and overall mineral structure. These findings provide clarification on the mineralisation pathways that coccolithophores and other biomineralising organisms use to control the formation of highly functionalised crystalline structures, particularly relevant in the design of materials with tunable properties.

biophysics↗

bioRxiv2024

Dynamic change of calcium-rich compartments during coccolithophore biomineralization

Coccolithophores are abundant marine phytoplankton that produce biomineralized calcite scales, called coccoliths, which sequester substantial amounts of carbon and play a significant role in biogeochemical cycles. However, mechanisms underlying the storage and transport of ions essential for calcification remain unresolved. We used ptychographic X-ray computed tomography under cryogenic conditions to visualize intracellular calcium-rich structures involved in the storage of calcium ions in the coccolithophore species Chrysotila carterae. During calcification, we observed a range of structures, from small electron-dense bodies within larger compartments, to denser and distributed globular compartments, before returning to small bodies once scale formation is complete. Nanobeam-scanning X-ray fluorescence measurements further revealed these electron-dense bodies are rich in P and Ca (molar ratio of [~]4:1). We infer from the dynamic nature of structures that these bodies are part of required cellular calcium ion transport pathways, a fundamental process critical for understanding the response of coccolithophores to climate change.

cell biology↗