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Possible role of lysosomes in the detoxication of copper in the digestive gland cells of metal-exposed mussels
Marine Environmental Research 14 (1984) 469 470
Possible Role of Lysosomes in the Detoxication of Copper in the Digestive Gland Cells of Metal-Exposed Mussels A. Viarengo, M. Pertica, G. Mancinelli & M. Orunesu Istituto di Fisiologia Generale, Universita di Genova, Italy
G. Zanicchi lstituto di Chimica Generale, Universita di Genova, Italy
& M. N. Moore & R. K. Pipe Institute for Marine Environmental Research, Plymouth, Great Britain
Previous results have demonstrated that the copper accumulated in the digestive gland cells of metal-exposed mussels is detoxified by two mechanisms: the increased synthesis of Cu-thioneins, and the accumulation of the metal in an insoluble form in lysosomes and residual bodies which are eliminated by exocytosis. Moreover it has been shown that Cuthioneins are rapidly eliminated during the detoxication period. These results prompted us to investigate the possible role of lysosomes in copper detoxication and, in particular, in the elimination of Cu-thioneins. Initially, a procedure to solubilize the compounds that complex Cu in lysosomes from the digestive gland was devised. This procedure is based on the sonication of lysosomes in a hypotonic solution of /3mercaptoethanol containing an antiproteolytic mixture (phenylmethyl sulphonylfluoride, trypsin inhibitor, leupeptin). The copper-rich fraction was then purified by acetone fractionation. The lysosomal acetone extracts'obtained from mussels exposed for 3 days to copper (0'04 ppm) and then detoxified for 6 days were analysed by gel filtration. The results demonstrate that approximately 80 % of the copper is 469 Marine Environ. Res. 0141-1136/84/$03.00 ,~i, Elsevier Applied Science Publishers Ltd,
England, 1984. Printed in Great Britain.
470
A. Viarengo et al.
bound to proteins having a molecular weight of about 12 000, similar to that of Cu-thioneins. Similar results were obtained when a fraction containing heavy lysosomes and residual bodies was employed. The possibility that Cu-thioneins accumulate in lysosomes and residual bodies was confirmed utilizing a cytochemical technique specific for thioneins. The above data suggest that lysosomes may play a role in the homeostasis as well as in the detoxication of copper, promoting the compartmentation and the elimination of the copper associated with the thioneins induced by the metal.
Possible Role of Lysosomes in the Detoxication of Copper in the Digestive Gland Cells of Metal-Exposed Mussels A. Viarengo, M. Pertica, G. Mancinelli & M. Orunesu Istituto di Fisiologia Generale, Universita di Genova, Italy
G. Zanicchi lstituto di Chimica Generale, Universita di Genova, Italy
& M. N. Moore & R. K. Pipe Institute for Marine Environmental Research, Plymouth, Great Britain
Previous results have demonstrated that the copper accumulated in the digestive gland cells of metal-exposed mussels is detoxified by two mechanisms: the increased synthesis of Cu-thioneins, and the accumulation of the metal in an insoluble form in lysosomes and residual bodies which are eliminated by exocytosis. Moreover it has been shown that Cuthioneins are rapidly eliminated during the detoxication period. These results prompted us to investigate the possible role of lysosomes in copper detoxication and, in particular, in the elimination of Cu-thioneins. Initially, a procedure to solubilize the compounds that complex Cu in lysosomes from the digestive gland was devised. This procedure is based on the sonication of lysosomes in a hypotonic solution of /3mercaptoethanol containing an antiproteolytic mixture (phenylmethyl sulphonylfluoride, trypsin inhibitor, leupeptin). The copper-rich fraction was then purified by acetone fractionation. The lysosomal acetone extracts'obtained from mussels exposed for 3 days to copper (0'04 ppm) and then detoxified for 6 days were analysed by gel filtration. The results demonstrate that approximately 80 % of the copper is 469 Marine Environ. Res. 0141-1136/84/$03.00 ,~i, Elsevier Applied Science Publishers Ltd,
England, 1984. Printed in Great Britain.
470
A. Viarengo et al.
bound to proteins having a molecular weight of about 12 000, similar to that of Cu-thioneins. Similar results were obtained when a fraction containing heavy lysosomes and residual bodies was employed. The possibility that Cu-thioneins accumulate in lysosomes and residual bodies was confirmed utilizing a cytochemical technique specific for thioneins. The above data suggest that lysosomes may play a role in the homeostasis as well as in the detoxication of copper, promoting the compartmentation and the elimination of the copper associated with the thioneins induced by the metal.