C Pantani

Microtox solid phase test: Effect of diluent used in toxicity test.

Microtox solid phase test is an acute toxicity test for solid matrices based on inhibition of natural bioluminescence of the marine bacterium Vibrio fischeri. Protocols developed to overcome the effects of confounding factors are proposed in the literature that differs by important practical and methodological issues. This work focused on diluents used for sediment resuspension and dilution. Two artificial seawaters, one natural seawater and two phosphate buffer solutions, were compared. The results showed that toxicity data obtained using different diluents were not comparable and that test sensitivity is highest using 0.1M phosphate buffer solution. The effects of medium on test organism were also investigated, in order to verify the capacity of media to maintain bioluminescence. The results underlined the importance of pH and Eh to explain the observed differences in toxicity.

EFFECTS OF MELANOPROTEINS AND THEIR PRECURSORS ON CELL PROLIFERATION THE PROBLEM OF SELECTIVITY

The actions of melanin and its precursors on mitotic frequencies, cell division and 3H‐thymidine incorporation in protokaryotic and eukaryotic cells are studied. It was also suggested that the binding of melanin precursors with proteins in the melanosomes is a way of scavenging a cytotoxia activity.

Effect of Particulate Matter on Copper and Surfactants' Acute Toxicity to Echinogammarus Tibaldii (Crustacea, Amphipoda)

The adsorbent capacity of particulate matter was well demonstrated especially for toxic substances with positive charge. In fact the acute toxicity of copper and cationic surfactants didodecyldimethylammonium bromide and cetyltrimethylammonium bromide towards the Crustacean Amphipod Echinogammarus tibaldii, was considerably reduced by adding fluvial sediment, humic acid and bentonite. For copper the highest detoxification seems to be carried out by humic acids, whereas, for cationic surfactants, by bentonite. The lower or nil detoxification of non ionic (polyethylene glycol dodecyl ether), anionic (sodium dodecylbenzensulphonate) and zwitterionic (tetradecyldimethylammonium propanesulphonate and cetyldimethylammonium methanecarboxylate), and the high detoxification of cationic surfactants, seems to confirm the major role of the “head” groups comparatively to the hydrocarbon tails in the interaction of those substances with the adsorbent materials. Nevertheless bentonite seems to exert a significant detoxi...