Meeting Abstract
Molluscan shells are mineral-organic composites with unique structural organization, and mechanical properties superior to geologic calcium carbonates. Outer mantle edge cells (OME) has been linked to biomineralization due to their proximity to the shell surface and ability to maintain shell deposition ex vivo, while other studies indicate that hemocytes (HCs) may also contribute to the shell building. However, the specific roles and interactions of these two cell types are unknown. We isolated four different fractions of HCs on a density gradient, and compared their gene expression profiles with the OME. Two HC fractions (H1 and H4) consisted of cells with long filamentous pseudopodia, had the highest adhesion capacity and motility of all HCs and presumably contained immune cells. HC fractions H2 and H3 consisted of irregularly shaped cells with no filamentous structures. These hemocytes had high levels of expression of ion regulatory genes and select matrix proteins (fibronectin Prot3, and fibronectin-ankyrin) as well as high intracellular [Ca2+] levels (in H2 fraction). OME had the highest expression of matrix proteins including silk-like protein and fibronectin Prot2, as well as chitin synthase II, the vascular endothelial growth factor (VEGF) and VEGF receptor. Our data indicate that H2 and H3 subpopulations of HCs play a role in biomineralization together with OME, and that HCs and OME specialize on different biomineralization-related functions. Supported by NSF IOS award 1557870.
