BENZO[a]PYRENE HYDROXYLASE AND GLUTATHIONE S-TRANSFERASE ACTIVITIES AS BIOMARKERS IN LYMNAEA PALUSTRIS (MOLLUSCA, GASTROPODA) EXPOSED TO ATRAZINE AND HEXACHLOROBENZENE IN FRESHWATER MESOCOSMS

Abstract

Abstract-Freshwater pond mesocosms were used to validate xenobiotic-metabolizing enzymes as biomarkers of contamination by atrazine and hexachlorobenzene (HCB) in a basommatophoran gastropod, Lymnaea palustris (Müller). Over long-term (21-d) exposure to 5, 25, and 125 g/L atrazine and to 0.5, 1.25, and 5 g/L HCB, the uptake and internal concentration of both pesticides were followed, and the activities of benzo[a]pyrene hydroxylase (BaPH) and glutathione S-transferases (GSTs) of pesticide-exposed snails were compared with those of control animals maintained in untreated mesocosms. Internally recovered HCB concentrations were much higher than internal atrazine concentrations, but the uptake of atrazine was faster than that of HCB. Although it affected the integrity of microsomal membranes, HCB had no relevant effects on BaPH and GST activities at concentrations which affected growth and fecundity, thus confirming the low inducibility of mollusc xenobiotic-metabolizing enzymes by chlorinated compounds. In contrast, atrazine markedly inhibited BaPH and both postmitochondrial and cytosolic GSTs at the same concentrations, which had no effects on growth or reproduction. Enzyme inhibition was negatively correlated with the maximal internal amount of atrazine and positively correlated with the bioconcentration factor, suggesting that effects on xenobiotic-metabolizing enzymes may affect pharmacokinetics of atrazine within the snail body. Correlation between the bioconcentration factor and enzyme inhibition may serve as a descriptor of the physiological status of animals and can also be used to indirectly estimate the pesticide concentration in the environment. Laboratory data were considered for the interpretation of results obtained in the mesocosms. In the biomarker context, BaPH and GST activities are proposed, along with other biochemical markers already identified in atrazine-and HCB-exposed L. palustris, as elements of a multiparametric approach of the ecotoxicological effects of pesticides on freshwater ecosystems.

Cholinesterase and glutathione‐S‐transferase activities in freshwater invertebrates as biomarkers to assess pesticide contamination

“…A study based on OP found induction occurred in C. fluminea after exposure to fenitrothion [47], and a concentration-dependent induction was observed after Limnea palustris was exposed to atrazine [59]. Two studies investigating the OC pesticides hexachlorobenzene, lindane, and dieldrin [59,60] found no induction of GST. In general, chlorinated compounds appear to demonstrate a weak capacity to induce GST in mollusks and insects.…”

“…Berra et al [56] found no mortality in Hydropsyche pellucidula exposed to fenitrothion concentrations that caused a 40% induction of GST. McLoughlin [4] observed a higher degree of sensitivity of GST for G. pulex exposed to lindane, permethrin, and pirimiphos methyl compared to a lethal response, while Baturo and Lagadic [59] observed the inhibition of GST in Lymnaea palustris by atrazine at concentrations that had no effects on growth and reproduction. Bhavan and Geraldine [20] exposed M. malcolmsonii to endosulfan and recorded a gradient of biochemical stress response: phosphatases > LDH (lactate dehydrogenase) > GST > protein denaturation > AChE.…”

Invertebrates in Testing of Environmental Chemicals: Are They Alternatives?

“…For such purposes, many calibrated individuals of selected invertebrate species, subspecies, or strains must be maintained under conditions that would be stressful for most vertebrates. In mesocosms or field-scale testing, macroinvertebrates have been widely used for experimental assessment of both risk and impact of chemicals (249,250,(333)(334)(335)(336)(337)(338)(339)(340)(341)(342)(343)(344)(345)(346)(347)(348)(349)(350)(351).…”

Validation ofhsp70stress gene expression as a marker of metal effects inDeroceras reticulatum(pulmonata): Correlation with demographic parameters

“…Also, changes in glycogen metabolism were correlated with the inhibition of body growth and the stimulation of egg production in atrazine‐exposed freshwater snails, Lymnaea palustris [19]. In the same species, both benzo[ a ]pyrene hydroxylase and glutathione S ‐transfer‐ase activity were inhibited by atrazine concentrations, which had no effects on growth or reproduction [20]. Thus, although high sensitivity should be a prerequisite of a suitable biomarker (and although the toxicological relevance of the mentioned marker responses may be high), the ecological relevance of these markers is questionable unless a demograhic parameter with similar sensitivity has been found.…”