Nacreous Luster Spun by Gene Expression

Nacreous luster is held in high industrial value since ancient time. It is a jewelry which is generated in pearl oysters, so it is also called “biomineral”. Nacre consists of two kinds of layer structures: an “inorganic crystal layer by calcium carbonate” and a “protein layer”. The protein layer is made of a laminate structure, which comes up the characteristic luster by multilayer reflective. Recently, pearls are not only used as jewels but take on greater importance like as a new functional material for nano technology, as a CO2 fixation carrier for environmental science, and as a model of bone formation/bio-calcification for medical science.

However, molecular entity of the protein layer is not understood so much. To clarify it, Kinoshita et al. tried transcriptome analysis of the pearl oyster Pinctada fucata with 3’-fragment library and GS FLX sequencing. They could identify 29,682 novel genes, and clustering analysis of gene expression pattern with known nacreous genes revealed 20 candidates that most probably have an association with bio-mineralization. Furthermore, Takeuchi et al.　determined the 1.15 Gb draft genome sequence of P. fukata. They found 23 257 complete gene models that included the candidate genes reported in the study from Kinoshita et al.

The spinning process of nacreous luster will be clarified by harmony of gene expression in near future!