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Mollusk shell formation is a fascinating aspect of biomineralization research. Shell matrix proteins play crucial roles in the control of calcium carbonate crystallization during shell formation in the pearl oyster, Pinctada fucata. Characterization of biomineralization-related genes during larval development could enhance our understanding of shell formation. Genes involved in shell biomineralization were isolated by constructing three suppression subtractive hybridization (SSH) libraries that represented genes expressed at key points during larval shell formation. A total of 2,923 ESTs from these libraries were sequenced and gave 990 unigenes. Unigenes coding for secreted proteins and proteins with tandem-arranged repeat units were screened in the three SSH libraries. A set of sequences coding for genes involved in shell formation was obtained. RT-PCR and in situ hybridization assays were carried out on five genes to investigate their spatial expression in several tissues, especially the mantle tissue. They all showed a different expression pattern from known biomineralization-related genes. Inhibition of the five genes by RNA interference resulted in different defects of the nacreous layer, indicating that they all were involved in aragonite crystallization. Intriguingly, one gene (UD_Cluster94.seq.Singlet1) was restricted to the ‘aragonitic line’. The current data has yielded for the first time, to our knowledge, a suite of biomineralization-related genes active during the developmental stages of P.fucata, five of which were responsible for nacreous layer formation. This provides a useful starting point for isolating new genes involved in shell formation. The effects of genes on the formation of the ‘aragonitic line’, and other areas of the nacreous layer, suggests a different control mechanism for aragonite crystallization initiation from that of mature aragonite growth.

The catalytic performance of noble metal nanocrystals highly depends on their surface structure and interface structure. Effective surface/interface control over noble metal nanocrystals can significantly improve their electrocatalytic activity, durability, and selectivity for the various important electrochemical reactions in low-temperature polymer electrolyte fuel cells. In this work, the polyallylamine (PAA)-functionalized Pt nanostructures with long-spined sea-urchin-like morphology (Pt-LSSUs@PAA) have been synthesized successfully through a simple chemical reduction route. The high branching degree of Pt-LSSUs@PAA nanostructures and the sheet morphology of the branches effectively improve the utilization of the Pt metal. The particular 3D interconnected architecture of Pt-LSSUs@PAA nanostructures significantly enhances the electrochemical stability. Loose-packed PAA layers on the surface of Pt-LSSUs@PAA nanostructures efficiently modify the electronic property of Pt atoms and serve as barrier networks to restrain the accessibility of alcohol molecules. As a result, the as-prepared Pt-LSSUs@PAA nanostructures show high activity, excellent durability, and particular alcohol tolerance for the oxygen reduction reaction in acidic media.