Evolution of Nacre: Biochemistry and Proteomics of the Shell Organic Matrix of the Cephalopod Nautilus macromphalus

Abstract

Matrix evolutions: We have biochemically characterized the nacre matrix of the cephalopod Nautilus macromphalus, in part by a proteomic approach applied to the acetic acid‐soluble and ‐insoluble shell matrices, as well as to spots obtained after 2D gel electrophoresis. Strikingly, most of the obtained partial sequences are entirely new, whereas a few correspond only partly with bivalvian nacre proteins. Our findings shed new light on the macroevolution of nacre matrix proteins. magnified imageIn mollusks, one of the most widely studied shell textures is nacre, the lustrous aragonitic layer that constitutes the internal components of the shells of several bivalves, a few gastropods, and one cephalopod: the nautilus. Nacre contains a minor organic fraction, which displays a wide range of functions in relation to the biomineralization process. Here, we have biochemically characterized the nacre matrix of the cephalopod Nautilus macromphalus. The acid‐soluble matrix contains a mixture of polydisperse and discrete proteins and glycoproteins, which interact with the formation of calcite crystals. In addition, a few bind calcium ions. Furthermore, we have used a proteomic approach, which was applied to the acetic acid‐soluble and ‐insoluble shell matrices, as well as to spots obtained after 2D gel electrophoresis. Our data demonstrate that the insoluble and soluble matrices, although different in their bulk monosaccharide and amino acid compositions, contain numerous shared peptides. Strikingly, most of the obtained partial sequences are entirely new. A few only partly match with bivalvian nacre proteins. Our findings have implications for knowledge of the long‐term evolution of molluskan nacre matrices.

Nacre in Molluscs from the Ordovician of the Midwestern United States

“…However, Vendrasco et al [9] concluded that nacre instead convergently evolved in early molluscs because: (1) there are no clear cases of nacre in molluscs from the early or middle Cambrian, in spite of much data on their shell microstructures; (2) there are differences in the microscopic form and growth method of nacre between modern molluscan classes; (3) the constituent proteins differ markedly between nacre-bearing molluscs [47]; (4) the genes associated with nacre vary among modern classes of mollusc [48]; and (5) many modern monoplacophorans have foliated (or semi-foliated) aragonite instead of or together with nacre in their inner shell.…”

Novel Molluskan Biomineralization Proteins Retrieved from Proteomics: A Case Study with Upsalin

“…Briefly, the fraction was enzymatically digested with trypsin [57] and then purified with a Vivapure C18 micro membrane (Vivascience). The purified samples were analyzed by nano-LC-MS/MS with a nano-Liquid Chromatography system (LC Packings, Dionex) and a nano-ESI-qQ-TOF mass spectrometry system (QSTAR XL, AB Sciex).…”

“…Mass spectrometry data were acquired with use of Analyst QS 1.1 software (AB Sciex) operated in IDA mode as previously described. [57] Protein identification was performed with ProteinPilot 3.0 software (Applied Biosystems) with use of the Paragon database search algorithm and the sequence determined from the DNA sequencing.…”

Review of recent proteomic applications in aquatic toxicology

“…Of those published, many have focused on bivalve species, such as marine mussels of the genus Mytilus (M. edulis, M. galloprovincialis, M. trossulus) that reside off the European coast. Most of the studies published have utilized proteomic analysis to examine taxonomic differences [42][43][44][45][46][47], heritability [48], and evolution of the nacre [49]. One of the first environmental toxicology proteomic studies with aquatic invertebrates was conducted on Mytilus.…”