Characteristic of spleen macrophage aggregates in Anguilla anguilla from Mar Menor Lagoon (Western Mediterranean) related to metalloid and metal exposure

Resumen

Melano-macrophage aggregates (MMAs) located in different organs of non-mammalian vertebrates, play a role in the destruction, detoxification or recycling of endogenous and exogenous materials and they are considered a biomarker for contaminant toxicity. To elucidate the relationship between MMAs and metals exposure, 40 European eels (Anguilla anguilla), 12 yellow eels and 28 silver ones, were sampled from Mar Menor lagoon. Metals (Fe, Zn, Pb, Cu, Ni, Cd and Mn) and metalloid (As) concentrations in liver and muscle were determined by Inductively Coupled Plasma Optical Emission Spectrophotometer. Spleen samples were fixed with 10% buffered formalin, processed for routine paraffin embedding, sectioned at 5μm and stained with hematoxylin and eosin. Each of 5 fields of view at 100x magnification were photographed. The mean percentage coverage of MMAs, in relation to the field of view, the size and density of MMAs were calculated by using Leica Qwin software. Additionally, the hepatosomatic index (HI) and corporal condition (K) were obtained. Statistically differences were found in Fe, Zn, Cu, Pb concentration in muscle between the two group of eels, as well as between Zn, Ni, Cd, As and Mn concentrations in liver. Negative correlations were observed between Cd concentrations in kidney and HI and K index, and between Ni concentration in kidney and IH. No correlation between the MMA measured parameters and inorganic element concentrations in liver were observed while negative correlations were observed between MMA density and Zn, Cu and Mn concentration in muscle, and between areas occupied by MMAs and Cu concentration in muscle. The implications of metal levels, tissue distribution and the relationship with measured indexes are discussed.