Macromolecular structure of the organic framework of nacre in Haliotis rufescens: implications for mechanical response.

Direct experimental probes of the mechanical response of the biopolymer framework of nacre extracted from the shell of the gastropod Haliotis rufescens have been performed. Both monotonic tensile, and time dependent relaxation, tests revealed that the tissue comprising the interlamellar layers within nacre obeyed a simple constitutive model conforming to the visco-elastic standard linear solid, with time constants in the range tau=140+/-4s. We conclude that the behavior is essentially that imparted by the chitin core of these layers.

Macromolecular structure of the organic framework of nacre in Haliotis rufescens: implications for growth and mechanical behavior.

We have performed a macromolecular structural analysis of the interlamellar and intertabular parts of the organic framework of the nacreous part of the shell of Haliotis rufescens, including the identification of structural chitin. Using histochemical optical microscopy we have mapped the locations of carboxylates and sulfates of proteins and chitin on the surfaces and within the core of the interlamellar layers and the intertabular matrix that together form the external organic matrix of composite nacre. This extends the earlier work of Nudelmann et al.