Inhibition of esterases in the marine gastropod Littorina littorea exposed to cadmium.
Electrophoretic analysis of Littorina littorea esterases indicated the presence of a cathodal migration isoenzyme (EST-C), which was identified in extracts obtained from the gonad-digestive gland complex. A loss of EST-C enzyme activity was observed in individuals exposed to Cd2+. This loss of activity was complete in 86% of individuals dead by the action of Cd2+ and in 68% of those individuals that survived Cd2+ exposure. This difference was statistically significant. In vitro inhibition of esterases by different concentrations of Cd2+ and Cu2+ was studied in individuals not experimentally exposed to heavy metals, to determine whether EST-C inhibition was caused by direct binding of Cd2+ to the esterase molecule or by Cd2+ displacement of a metal ion from essential Cu2+- or Zn2+-containing proteins, which may then be responsible for the inhibition of esterase. Contrary to what happened when individuals were exposed to Cd2+, in the in vitro experiment with Cd2+, inhibition of anodal but not cathodal systems was observed. At the same time, when Cu2+ was used in the in vitro experiment, both anodal and cathodal systems were inhibited. These results suggest that the inhibition of EST-C activity by Cd2+ takes place in vivo and seems not to be due to the direct action of Cd2+ on the molecule, but rather is a process in which transcriptional, posttranscriptional, and other inhibitory processes may be involved.
Mazón
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LI
Departamento de Biología Animal y Genética, Universidad del País Vasco, Bilbao, 48080, Spain.
Gonzalez
G
G
Vicario
A
A
Estomba
A
A
Aguirre
A
A
D000818:Animals; D002104:Cadmium / Q000009:adverse effects*; D003300:Copper / Q000009:adverse effects; D029721:Drosophila Proteins; D004950:Esterases / Q000037:antagonists & inhibitors*; D007527:Isoenzymes / Q000037:antagonists & inhibitors*; D008974:Mollusca / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D014874:Water Pollutants, Chemical / Q000009:adverse effects*
D029721:Drosophila Proteins; D007527:Isoenzymes; D014874:Water Pollutants, Chemical; D002104:Cadmium; D003300:Copper; D004950:Esterases; C101966:alpha-Est5 protein, Drosophila