Metalloproteomic study of biomarkers of mercury exposure in breast milk samples from the Amazon region - Brazil.

Abstract

Breast milk is the main source of available nutrients for breastfeeding women and the mother's diet may have a significant influence on their composition. Studies have indicated high concentrations of mercury in breast milk from mothers who feed on large quantities of contaminated fish. Mercury levels in breast milk are about one-third the level of mercury in the mother's blood. The high levels of mercury found in humans in the Brazilian Amazon have been intensively studied by the scientific community in the last decades, seeking to elucidate the mechanisms of toxicity of mercury species in breast milk. The bioavailable fraction of mercury species in breast milk may be dependent on the way they are bounded to proteins. However, studies related to the elucidation of the mechanisms of mercury toxicity in humans of this region at a cellular level, which are of fundamental socio environmental importance, have not been explored yet. The development of biomarkers related to the mapping and expression of proteins associated to mercury may indicate beforehand possible risks of contamination and human exposure. In this context, the metallomics, a recently proposed scientific field, presents anew and innovative proposal for the identification of mercury biomarkers associated with proteins, contributing to the elucidation of the physiological and functional aspects responsible for the transport of mercury in human beings. Therefore, this research seeks to optimize: 2D-PAGE electrophoretic procedures for fractionation and identification of metalloproteins responsible for the transport of mercury in samples of breast milk collected in the Amazon region; method for the determination of mercury by GFAAS or CVAFS in the protein spots obtained; methodologies for speciation of mercury in breast milk samples; characterization of mercury-carrying metalloproteins by ESI-MS/MS; and finally the analysis of bioinformatics striving for possible correlation of the incorporation of the mercury in the structure of these proteins at physiological level. (AU)