First paleoproteome study of fossil fish otoliths and the pristine preservation of the biomineral crystal host

ABSTRACT: Otoliths are calcium carbonate components of the stato-acoustical organ of teleost fish responsible for hearing and maintenance of their body balance. The formation of modern fish otoliths, their morphology, and the selection of calcium carbonate polymorphs is influenced by complex insoluble collagen-like protein and soluble non-collagenous protein assemblages; many of these proteins are incorporated into the aragonite crystal structure. However, the survival of these proteins has been considered unlikely in fossil otholiths. Here we report the presence of 11 fish-specific proteins (and several isoforms) in Miocene (ca. 14.8–14.6 Ma) phycid hake otoliths. These fossil otoliths were preserved in water-impermeable clays and exhibit microscopic and crystallographic features indistinguishable from modern representatives, consistent with an exceptionally pristine state of preservation. Indeed, these fossil otoliths retain ca. 10% of the proteins sequenced from modern counterparts, including proteins specific to inner ear development, e.g., otolin-1-like proteins that are involved in the arrangement of the otoliths into the sensory epithelium, and otogelin/otogelin-like proteins are a component of all the acellular membranes of the inner ear. The specificity of these proteins excludes the possibility of external contamination. Identification of a fraction of identical proteins in modern and fossil phycid hake otoliths points to highly conservative functions of inner ear biomineralization processes through time.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Phycis Phycis

TISSUE(S): Otolith Organ, Bone

SUBMITTER: Jeana Drake  

LAB HEAD: Jeana Drake

PROVIDER: PXD036742 | Pride | 2023-03-03

REPOSITORIES: Pride