Meeting Abstract
Among mammals, the wing bones of extant bats are unusually resistant to fracture. Published studies have shown that, relative to terrestrial mammals, bat wing bones have thinner, rounded cortices with lower mineral composition. Unfortunately, no studies have identified the structural and developmental mechanisms that allow bat bones to bend with relative ease. Here we show that bat wing bones have a unique extracellular matrix composed of an abundance of organics that are organized generally into helical or longitudinal patterns along the length of the bone. Proximal elements known to be loaded in torsion display a helical wrapping of organics around the longitudinal axis of the bone, whereas those bones that primarily bend display a more longitudinal arrangement. In addition, our molecular assays show that bats, relative to rodents, have at least 10-fold greater expression in those genes associated with the synthesis of organics (e.g., Col1a1, Col1a2, Col5a1), and inhibitors of mineral deposition (e.g., VDR). Ongoing analyses will continue to identify unique gene expression patterns that ultimately create a mammalian limb with an extracellular matrix that is unusually resistant to fracture.
