A novel in vivo system to study coral biomineralization in the starlet sea anemone (Nematostella vectensis)

Coral reefs are important for maintaining healthy marine ecosystems and are declining rapidly due to increasing environmental stresses. Coral conservation efforts require a mechanistic understanding of how these stresses may disrupt biomineralization, but progress in this area has been slow primarily because corals are not easily amenable to laboratory research. Some cellular characteristics of biomineralization are well characterized, such as the role of carbonic anhydrases, the polarized secretion of ions, and the secretion of "intrinsically disordered proteins" (IDPs) into extracellular microenvironments. We highlight how the starlet sea anemone (Nematostella vectensis) can serve as a tractable model to interrogate the cellular mechanisms of coral biomineralization. We have developed transgenic constructs using genes involved in biomineralization from several animal phyla that can be injected into Nematostella zygotes. These constructs are designed so translated proteins may be purified using TEV protease or Histidine tags to study their physicochemical properties. Using a fluorescent tag, we confirm ectopic expression of the coral biomineralizing protein SpCARP1 in live Nematostella embryos and adults and demonstrate via calcein staining that calcium ions co-localize with SpCARP1 in carbonate and calcium enriched seawater. Our findings suggest that SpCARP1 can induce the formation of amorphous calcium carbonate precursors in N. vectensis, consistent with its suspected role in the early stages of coral biomineralization. These results lay a fundamental groundwork for establishing N. vectensis as a novel in vivo system to explore the evolutionary and cellular mechanisms of biomineralization, improve coral conservation efforts, and even develop novel biomaterials. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/560932v1_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@1170b4eorg.highwire.dtl.DTLVardef@1e7491corg.highwire.dtl.DTLVardef@1710cd1org.highwire.dtl.DTLVardef@100743b_HPS_FORMAT_FIGEXP M_FIG C_FIG