Mussels as sentinels of organotin pollution: bioaccumulation and effects on P450-mediated aromatase activity
1999
Morcillo, Y. | Albalat, A. | Porte, C.
Organotin pollution has been monitored in mollusks from the Catalan coast (Spain). Tributyltin (TBT) was the major compound detected, ranging from 200 to 1,100 ng/g wet weight as Sn. Tributyltin metabolites and triphenyltin (TPhT) were also detected although to a lesser extent. Virtually organotin-free mollusks were obtained in the Alfacs Bay (Ebro Delta). Aromatase activity was determined in the digestive gland of a selected number of samples by measuring the tritiated water release from [1beta-(3)H]-androstenedione. Enzyme activity was linear as a function of incubation time and protein content of the microsomal fraction. It was determined at a substrate concentration of 10 micromolar, and it exhibited a typical Michaelis-Menten kinetic, with an apparent constant, K(m), of 32 +/- 3 micromolar. Low aromatase activity (217-264 fmol/h/mg protein) was seen in mussels sampled in TBT-polluted environments compared with mussels from the virtually organotin-free point (345 fmol/h/mg protein). These results support the hypothesis of a TBT-mediated inhibition of cytochrome P450-aromatase activity in mussels, although no significant changes on tissue titers (if testosterone/estradiol were observed.
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