EFFECTS OF ALUMINUM CHLORIDE ON THE MUCOUS SECRETION IN THE STRIPED VENUS CLAM, CHAMELEA GALLINA

Al is toxic for many organisms1,2 and is responsible for neurodegenerative diseases in humans1. Although it is naturally occurring in aluminosilicate and oxide minerals3, anthropogenic activities determine a surplus of this metal in the environment. We estimated the alterations of mucous secretions in the Venus striped clam, Chamelea gallina, a marine bottom filter-feeder common in the Mediterranean and Eastern Atlantic, exploited in shellfisheries. Four groups, 20 individuals each, were housed for three days in 10L seawater aerated tanks with daily replacement of water. Animals were fed daily with 50cc of algae. Three groups were treated for three days with AlCl3 at 25 M, 50 M, and 200 M, respectively, the fourth being used as a control. Three individuals died in the treatment at 25 M, 14 in the 50 and 14 in the 200. The survivors were sedated, and tissue samples of gills and feet were processed for routinely paraffin inclusion. Sections of 5 m were analysed by histochemical methods such as PAS, AB pH 2.5, HID-AB pH 2.5 and FITC-lectins (PNA, desolation-PNA, SBA, desulfation-SBA, WGA, AAA, ConA, UEA I, MAA II, LTA, SNA). Controls were positive for PAS, AB pH 2.5, and stained brown with HID-AB pH 2.5, indicating the presence of sulfated glycans. ConA positivity revealed that the deep mucous cells of the foot produce a secretion with mannosylated and/or glycosylated residuals. The glycocalyx of the epidermal layer of the foot was rich in fucosylated residuals and poor in glycosaminylated/sialylated ones, as revealed by AAA and WGA binding, respectively. Gill filaments strongly linked AAA and WGA. A general reduction in staining/binding was observed in the high doses treated. From the previous, we can preliminarily conclude that high dosages of AlCl3 affect the quali-quantitative expression of glycans in the mucous secretion.