Acantharea are marine, unicellular organisms that produce endoskeletal spicules comprised of celestine (SrSO4), a highly unusual biomineral. This capability is remarkable not only because of the high level of biological control over single-crystal growth evident in species-specific morphological features, but also because of the high selectivity for strontium ion. In most organisms, including humans, the chemical similarity of Ca2+, Sr2+, and Ba2+ leads to indiscriminate transport. As a consequence, 90Sr is readily taken up and incorporated into mineralized tissues such as bone, where its radioactive decay is a long-term cancer hazard. Yet, Acantharea sequester Sr2+ from seawater, where Ca2+ is present in more than 100 fold excess. Clearly, Acantharea have evolved to manipulate Sr ions and SrSO4 far beyond human capabilities. Despite their exceptional features, Acantharea biomineralization remains largely unexplored and there are no genomic resources available. In preliminary work, the project team has made great progress in collecting, preserving, and analyzing Acantharea from across the globe. There is now compelling evidence for the presence of occluded biomacromolecules in single crystalline spicules. Furthermore, a workflow for analyzing the elemental distribution across single cells using X-ray fluorescence microscopy has been developed. Based on these developments, Co-PIs Joester and Alvares have teamed up to create a 3-year program that will establish the identity of molecular players and mechanisms that are involved in the selective sequestration of Sr ions from seawater and the control over celestine single crystal growth. This project represents the first comprehensive approach to date and will achieve the following objectives: a) Determine the transcriptome of several species of acantharea, and of several developmental stages of one species, using single-cell next generation sequencing technology; b) Identify intra-crystalline and Sr-binding proteins involved in guiding crystal growth in acantharea using proteomics; c) Determine subcellular trafficking pathways for strontium and sulfate using advanced X-ray fluorescence microscopy and correlative imaging techniques; This project is a first-principles study of the fundamental molecular players and mechanisms that allow Acantharea to sequester Sr from seawater and control celestine crystal growth. Identifying the molecules and mechanism behind selective Sr uptake will be a first step towards designing biotechnological or chemical approaches to remove 90-Sr from the environment or nuclear waste, thereby protecting Army personnel and civilians from accidental contamination, deliberate release, or radioactive fallout. Understanding biochemical mechanisms and design principles underpinning SrSO4 crystal growth will additionally help us master organismal capabilities and apply them to the synthesis of new materials.
|Effective start/end date||5/20/20 → 5/19/23|
- Army Research Office (W911NF2010137 P00002)
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