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Rapid evolution of pearl oyster shell matrix proteins with repetitive, low-complexity domains.

ABSTRACT: The lysine (K)-rich mantle protein (KRMP) and shematrin protein families are unique to the organic matrices of pearl oyster shells. Similar to other proteins that are constituents of tough, extracellular structures, such as spider silk, shematrins and KRMPs, contain repetitive, low-complexity domains (RLCDs). Comprehensive analysis of available gene sequences in three species of pearl oyster using BLAST and hidden Markov models reveal that both gene families have large memberships in these species. The shematrin gene family expanded before the speciation of these oysters, leading to a minimum of eight orthology groups. By contrast, KRMPs expanded primarily after speciation leading to species-specific gene repertoires. Regardless of their evolutionary history, the rapid evolution of shematrins and KRMPs appears to be the result of the intrinsic instability of repetitive sequences encoding the RLCDs, and the gain, loss and shuffling of other motifs. This mode of molecular evolution is likely to contribute to structural characteristics and evolvability of the pearl oyster shell. Based on these observations, we infer that analogous RLCD proteins throughout the animal kingdom also have the capacity to rapidly evolve and as a result change their structural properties.

SUBMITTER: McDougall C

PROVIDER: S-EPMC3627088 | biostudies-literature | 2013 May

REPOSITORIES: biostudies-literature

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Rapid evolution of pearl oyster shell matrix proteins with repetitive, low-complexity domains.

McDougall Carmel C Aguilera Felipe F Degnan Bernard M BM

Journal of the Royal Society, Interface 20130220 82

The lysine (K)-rich mantle protein (KRMP) and shematrin protein families are unique to the organic matrices of pearl oyster shells. Similar to other proteins that are constituents of tough, extracellular structures, such as spider silk, shematrins and KRMPs, contain repetitive, low-complexity domains (RLCDs). Comprehensive analysis of available gene sequences in three species of pearl oyster using BLAST and hidden Markov models reveal that both gene families have large memberships in these speci ...[more]

PMID: 23427100

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Project description:BackgroundColor polymorphism in the nacre of pteriomorphian bivalves is of great interest for the pearl culture industry. The nacreous layer of the Polynesian black-lipped pearl oyster Pinctada margaritifera exhibits a large array of color variation among individuals including reflections of blue, green, yellow and pink in all possible gradients. Although the heritability of nacre color variation patterns has been demonstrated by experimental crossing, little is known about the genes involved in these patterns. In this study, we identify a set of genes differentially expressed among extreme color phenotypes of P. margaritifera using a suppressive and subtractive hybridization (SSH) method comparing black phenotypes with full and half albino individuals.ResultsOut of the 358 and 346 expressed sequence tags (ESTs) obtained by conducting two SSH libraries respectively, the expression patterns of 37 genes were tested with a real-time quantitative PCR (RT-qPCR) approach by pooling five individuals of each phenotype. The expression of 11 genes was subsequently estimated for each individual in order to detect inter-individual variation. Our results suggest that the color of the nacre is partially under the influence of genes involved in the biomineralization of the calcitic layer. A few genes involved in the formation of the aragonite tablets of the nacre layer and in the biosynthesis chain of melanin also showed differential expression patterns. Finally, high variability in gene expression levels were observed within the black phenotypes.ConclusionsOur results revealed that three main genetic processes were involved in color polymorphisms: the biomineralization of the nacreous and calcitic layers and the synthesis of pigments such as melanin, suggesting that color polymorphism takes place at different levels in the shell structure. The high variability of gene expression found within black phenotypes suggests that the present work should serve as a basis for future studies exploring more thoroughly the expression patterns of candidate genes within black phenotypes with different dominant iridescent colors.

Dataset Information

Rapid evolution of pearl oyster shell matrix proteins with repetitive, low-complexity domains.

Publications

Rapid evolution of pearl oyster shell matrix proteins with repetitive, low-complexity domains.

Similar Datasets

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