Zinc accumulation in phosphate granules of Ucides cordatus hepatopancreas

Amorphous phosphate granules are present in vertebrate and invertebrate org anisms. The functions attributed to these structures depend on their minera l contents and organic matrix composition. In the present study we have det ermined zinc concentrations in the hepatopancreas of the crab Ucides cordat us from regions contaminated with zinc, and the elemental composition of he patopancreal phosphate granules. Organisms were collected from the contamin ated areas of Sepetiba Bay (SB) and Guanabara Bay (GB), and from a non-cont aminated area, Ribeira Bay (RB). The first two sites are located near the m etropolitan region of Rio de Janeiro city, Brazil. Atomic absorption spectr oscopy (AAS) showed a significant difference (P<0.05) for zinc concentratio n in the hepatopancreas from organisms collected at the contaminated sites GB (210 +/- 20 mu g/g dry weight) and SE (181 +/- 16 mu g/g dry weight) com pared to the non-contaminated site RE (76 +/- 14 mu g/g dry weight). Phosph ate granules isolated from hepatopancreatic tissue were studied by electron diffraction (ED), energy dispersive Xray analysis (EDX) and electron spect roscopic imaging (ESI). ED of granules presented no diffraction spots, indi cating that these structures are in an amorphous state, while EDX of granul es isolated from a contaminated area contained P, Ca and Zn. Mg, Cl and Fe were also found in some of the spectra. ESI showed that O, P and Ca were co localized in the mineralized layers of most granules observed. The correlat ion between the results obtained by PLAS and those obtained by microanalyti cal techniques suggests that the hepatopancreatic granules of U. cordatus m ay be related to the phenomenon of heavy metal retention.