Cypraea tigris shells: Determination of trace elements and their relation to proteins with INAA help

SOLDATI, ANALIA L.; VICENTE VILAS, VÍCTOR; NASCIMIENTO JÄHNKE, SAMARA; SOUND, IRIS; BAUMAN, WOLFRAM

Río de Janeiro, Brasil

Conferencia; Nuclear Analytical Methods in Life Sciences (NAMLS08); 2005

Nuclear Energy Centre for Agriculture, University of São Paulo (CENA/USP) and Brazilian Society for Metrology (SBM)

There are many studies about the occurrence of trace metals in soft bodies of marine creatures [1,2,3], but very little about the species, binding forms and oxidation states in their shells. The function of complexed metals in shells Is very wide-spanned, from pigmentation to defensive properties and structural hardening. The present study focuses mainly on the complexation of Br, Ca, Co, Cr, Fe, Mn, K, Na, Ni, Sr and Zn in Cypraea tigris shells. Five optically differentiate shell layers were carefully separated using a diamond milling cutter and analyzed for trace elements by Instrumental Neutron Activation Analysis (INAA). The proteins present in each layer were extracted with acetic acid buffer[4] and their concentrations show to be quite different in the different layers. Further characterization of the protein molecular fraction in the shell layers was done by chromatographic techniques, such as reversed phase high performance liquid chromatography (HPLC) online coupled to mass spectrometry (MS). Interesting correlations are presented as observed between some element concentrations, the layer structure, the protein content, and the mass fractions.   [1] H. Azouzi, Multielemental analysis of mussel samples by atomic absorption spectrometry after room temperature sonication; 1 Anal. Atomic Spect. Vol 13 (1988) 533-538. [2] D. Arabinda, Metal speciation in solid matrices, Review; Talanta 42 (1995) 1007-1030. [3] O. Ravera, Trace element concentrations in freshwater mussels and macropytes as related to those in their environment; J. Limnol. (2003) 62 (1) 61-70. [4] Y. Dauphin, Structure and composition of the aragonitic crossed lamellar layers in six species ofBivalvia and Gastropoda; Comp. Biochem. Physiol. Part A 126 (2000) 367-377.