Uptake and effects on detoxication enzymes of cypermethrin in embryos and tadpoles of amphibians
ABSTRACT A number of factors have been suggested for recently observed amphibian decreases, and one potential factor is pesticide exposure. We studied the uptake and effects of environmentally relevant concentrations of the pyrethroid insecticide cypermethrin on two different amphibian species, Bombina variegata and Rana arvalis. The uptake from water of 14C-labeled cypermethrin (0.4 microg/L) by eggs and tadpoles of B. variegata was investigated. After 24 hours of exposure, 153.9 ng cypermethrin/g fresh weight were found in embryos, thus indicating that the jelly mass of the eggs does not act as a sufficient physical barrier to protect embryos from exposure to this compound. Uptake of cypermethrin into tadpoles of both species and in all exposed individuals caused dose-dependent deformities; behavioral abnormalities such as twisting, writhing, and coordinated swimming; and mortality. In tadpoles of B. variegata and R. arvalis, the activity of microsomal and cytosolic glutathione S-transferase (mGST and sGST, respectively) were measured after treatment with cypermethrin. Activities of both GST systems increased significantly with increasing duration and concentration of cypermethrin exposure, with the reaction seeming stronger in B. variegata than in R. arvalis tadpoles. Alpha-cypermethrin--a racemic mixture of two cis isomers of cypermethrin--induced a stronger enzymatic response in the cytosolic fraction of R. arvalis tadpoles than cypermethrin at the same concentration. The observed physical and behavioral abnormities caused by environmentally relevant concentrations of cypermethrin indicate that despite detoxication of the chemical via GST-system contamination of ponds by cypermethrin could result in adverse effects on the development of amphibian embryos and tadpoles.
SourceAvailable from: library2.usask.ca
[Show abstract] [Hide abstract]
ABSTRACT: Exposure to pesticide residues is claimed to be one of the possible causes of frog decline. Knowledge of basic information on the uptake, metabolism and depuration processes of pesticides in the frog is needed to understand the relationship between exposure and toxic effects from their actual body burden, together with their bioconcentration. The hydrophobicity of pesticides and industrial chemicals was one of the most important factors controlling bioconcentration, similarly to fish, when frogs are exposed to contaminated water. Skin absorption was also a key route in the uptake process especially in the adult frog. The metabolic profiles in the frog, mainly examined by an intraperitoneal injection technique, were common to other aquatic species without any frog-specific transformation reaction. The effects of developmental stage, sex, species and environmental factors such as temperature were observed for bioconcentration and metabolism.Journal of Pesticide Science 01/2014; 39(2):55. DOI:10.1584/jpestics.D13-047 · 0.51 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Different enzyme biomarkers (AChE: acetylcholinesterase, CbE: carboxylesterase, GST: glutathione-S-transferase, CAT: catalase) were measured in digestive tissues of Lysapsus limellum frogs collected from a rice field (RF: chlorpyriphos sprayed by aircraft) and a non-contaminated area (RS: reference site), immediately (24h) and 168h after aerial spraying with chlorpyrifos (CPF). CPF degradation was also searched in water samples collected from RF and RS, and found that insecticide concentration was reduced to≈6.78% of the original concentration in RF at 168h. A significant reduction of AChE and CbE activities was detected in L. limellum from RF in stomach and liver at 24 and 168h, and in intestine only at 24h, with respect to RS individuals. CAT activity decreased in intestine of L. limellum from RF 24h and 168h after exposure to CPF, whereas GST decreased in that tissue only at 24h. In stomach and liver, a decrease was observed only at 168h in both CAT and GST. The use of biomarkers (AChE, CbE, GST, and CAT) provides different lines of evidences for ecotoxicological risk assessment of wild frog populations at sites contaminated with pesticides. Copyright © 2014 Elsevier Inc. All rights reserved.Ecotoxicology and Environmental Safety 12/2014; 113C:287-294. DOI:10.1016/j.ecoenv.2014.12.021 · 2.48 Impact Factor