Effects of heavy metals on phospholipase C in gill and digestive gland of the marine mussel Mytilus galloprovincialis Lam.
We studied the in vivo and in vitro effects of Hg2+ and Cu2+ on the activity of phospholipase C (PLC), specific for phosphatidylinositol 4,5-bisphosphate, in the mussel (Mytilus galloprovincialis Lam). The enzyme activity was assayed in tissue homogenates from gills and digestive gland. The toxic effect of Hg2+ appeared to be stronger than that of Cu2+ both in vitro and in vivo, especially for the digestive gland. In in vitro tests, Hg2+ was able to inhibit PLC activity when added directly to the reaction mixture. Conversely, Cu2+ was effective only after preincubation, suggesting that the effect of the metal may be derived from lipid peroxidation due to Cu2+-induced oxyradical production. Treatment of mussels with sublethal concentrations of Hg2+ or Cu2+ in vivo produced significant PLC inhibition after 1 or 4 days, respectively. A recovery was reached after 7 days of in vivo metal incubation. Data indicate that in mussel gills and digestive gland heavy metals impair PLC activity, thereby affecting IP3-dependent Ca2+ signaling.
Panfoli
I
I
Department of Oncology, Biology and Genetics, University of Genova, Italy.
Burlando
B
B
Viarengo
A
A
D000818:Animals; D049872:Bivalvia / Q000201:enzymology*; D002118:Calcium / Q000378:metabolism; D003300:Copper; D005880:Gills / Q000201:enzymology; D006868:Hydrolysis; D008628:Mercury; D019216:Metals, Heavy; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism*
D019216:Metals, Heavy; D019269:Phosphatidylinositol 4,5-Diphosphate; D003300:Copper; D010738:Type C Phospholipases; D008628:Mercury; D002118:Calcium