Effects of exposure to oxamyl, carbofuran, dichlorvos, and lindane on acetylcholinesterase activity in the gills of the Pacific oyster Crassostrea gigas.

Acetylcholinesterase (AChE) activity has been used to test the exposure of mollusk bivalves to pesticides and other pollutants. The Pacific oyster Crassostrea gigas is a species with a worldwide distribution, and it has a high commercial value. The use of this species as a bioindicator in the marine environment, and the use of measurements of AChE activity in tissues of C. gigas require prior evaluation of organisms exposed to several toxic compounds in the laboratory. In our study, the effects of pesticides on AChE activity in the gills and mantle tissues of C. gigas were analyzed by exposing animals to organophosphate (dichlorvos), carbamate (carbofuran and oxamyl), and organochlorine (lindane) pesticides. Adult Pacific oysters were exposed to several concentrations (0.1-200 microM) of dichlorvos, carbofuran, and oxamyl for 96 h, and lindane (1.0 and 2.5 microM) was applied for 12 days. In gill tissues, all pesticides analyzed caused a decrease in AChE activity when compared to the control unexposed group. The mean inhibition concentration (IC(50)) values were determined for dichlorvos, carbofuran, and oxamyl pesticides. Dichlorvos had the highest toxic effect, with an IC(50) of 1.08 microM; lesser effects were caused by oxamyl and carbofuran, with IC(50)s of 1.67 and 3.03 microM, respectively. This study reports the effects of pesticides with several chemical structures and validates measurement of AChE activity in the gill tissues of C. gigas for use in environmental evaluations or food quality tests.

Validation of an enzyme-linked immunosorbent assay for measuring vitellogenin in California halibut (Paralichthys californicus).

Vitellogenin (VTG) is the major protein present in the plasma of females undergoing oogenesis. In males, the VTG gene normally is suppressed; however, synthesis of VTG can be induced by exposure to xenoestrogenic compounds. In the present study, an enzyme-linked immunosorbent assay was developed and validated to evaluate VTG levels in the California halibut (Paralichthys californicus). Vitellogenin and lipovitellin (LV) were identified in the plasma of 17 beta-estradiol-induced females and in the ovaries of wild females, to our knowledge for the first time. Purified VTG from the plasma of induced females was obtained, and polyclonal antibodies against the LV of mature female ovaries was prepared and their specificity assessed by Western blot analysis. At Bahía Magdalena, Baja California Sur, México, quantitative measurements of VTG in the plasma of female specimens were made during one reproductive cycle.