Preserved macroscopic polymeric sheets of shell-binding protein in the Middle Miocene (8 to 18 Ma) gastropod Ecphora

Abstract

Geochemical Perspectives Letters Letter Letter Geochemical Perspectives Letters gastropods that lived from the late Oligocene to the Pliocene (Carter et al., 1994; Ward and Andrews, 2008). Ecphora in its various species and subspecies span nearly 10 Ma of time along Calvert Cliffs, Maryland within the Calvert, Choptank and St. Marys Formations. This genus is unique in the context of the Calvert Cliffs fauna, in that pronounced colouration is preserved in the sculpted calcitic (CaCO 3) outer shell layer, as opposed to the white aragonitic (also CaCO 3) nacreous inner shell layer (Fig. 1C). Most other mollusk shells of the Calvert Cliffs are composed principally of aragonite and occur as white chalky shells, or are completely leached out of some beds (Shattuck, 1904; Vokes, 1957; Petuch and Drolshagen, 2010). By contrast, Ecphora found in situ invariably maintains its rich red-brown colour, which fades gradually to light tan when exposed to sunlight. This striking colouration is preserved in specimens as old as 18 Ma and suggests the possibility that biomolecular fossils of shell-binding proteins and associated pigments might be preserved. Figure 1 A. Image showing characteristic colouration and shape of Ecphora gardnerae germonae; St. Marys Formation, Little Cove Point member, Driftwood Beach, Calvert County MD. B. Polymeric protein-rich residue from the calcitic portions of dissolved Ecphora shell from a St. Marys Formation, Driftwood Beach specimen. This material gives the distinctive colour to the shells. C. A polished cross-section of two costae from Ecphora gardnerae germonae reveals the colored calcitic outer layer and white aragonitic inner layer.

Detection of intact polyene pigments in Miocene gastropod shells

“…However, although proteinaceous material has been reported from shells of the Miocene gastropod Ecphora (Nance et al . 2015), in the present work, no indications were found that the polyenes of the cerithioidean gastropods could be bound to proteins. Nevertheless, it has to be considered that the actual colour of the polyene‐containing Miocene gastropods during lifetime may have been different to orange‐red, if they were bound to proteins.…”

“…Putative carotenoproteins have been reported for the brachiopod Calloria from the Late Pleistocene of New Zealand (Curry 1999) and the gastropod Ecphora from the Middle Miocene of North America (Nance et al . 2015), but both studies mainly focused on the characterization of the proteinaceous material or the content of amino acids with very little information on the associated pigments. Otherwise, only hydrogenated carotenoids (non‐coloured carotanes) have been reported from fossil organisms, such as β ‐carotane that was detected in Pseudofagus leaves from the Miocene of Clarkia, Idaho (Giannasi & Niklas 1981).…”

Polyene-based colouration preserved in 12 million-year-old gastropod shells

“…Interaction of unmethylated polyenes (psittacofulvins) with the protein keratin have been reported too (Stradi et al, 2001). However, although proteinaceous material has been reported from shells of the Miocene gastropod Ecphora (Nance et al, 2015), in the present work, no indications were found that the polyenes of the cerithioidean gastropods could be bound to proteins. Nevertheless, it has to be considered that the actual colour of the polyene-containing Miocene gastropods during lifetime may have been different than orange-red, if they were bound to proteins.…”

“…Raman spectroscopy has been used to search for carotenoid pigments in amber-preserved feathers, but distinctive carotenoidinformative bands (at 1530 and 1153 cm -1 ) have been only obtained for present-day, but not for fossil feathers (Thomas et al, 2014b). Putative carotenoproteins were reported for the brachiopod Calloria from the Late Pleistocene of New Zealand (Curry, 1999) and the gastropod Ecphora from the Middle Miocene of North America (Nance et al, 2015), but both studies mainly focused on the characterization of the proteinaceous material or the content of amino acids with very little information on the associated pigments. Otherwise, only hydrogenated carotenoids (non-coloured carotanes) have been reported from fossil organisms, such as β-carotane that was detected in Pseudofagus leaves from the Miocene of Clarkia, Idaho (Giannasi and Niklas, 1981).…”

Deep Time Paleoproteomics: Looking Forward

“…The examination of specimens older than 1 Ma for preserved proteins began as early as the 1950s with non-MS approaches, including immunology, − amino acid analyses, − and nonproteomic MS approaches such as pyrolysis gas chromatography mass spectrometry (PY-GC-MS) , and time-of-flight secondary ion mass spectrometry (TOF-SIMS) . However, although the molecular techniques used to detect original organic constituents in fossils (e.g., Raman spectroscopy, , Fourier transform infrared spectroscopy [FT-IR], , TOF-SIMS) have become increasingly sophisticated and have typically remained more accessible and inexpensive than MS, only MS approaches (and MS/MS in particular) have the ability to generate the peptide sequence information .…”