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PW12 Pesticide II
(PW211) Investigation of sublethal developmental and immune effects of atrazine on Xenopus laevis.
Baer, K1, Gibble, R1, 1 University of Louisiana at Monroe, Monroe, LA, USA
ABSTRACT- Adult fitness in amphibians is dependent upon proper larval development. Subtle, xenobiotic-induced disruption of these developmental processes can profoundly impact the contribution of an individual to the population. Critical developmental processes include growth rate and immune-related parameters. Bioactive peptides secreted from dermal granular glands in amphibian species are known to possess antimicrobial activity against a variety of pathogens. These peptides are putative components of the amphibian immune system and may serve as a first line of defense against pathogens that cross the epidermis. Therefore, xenobiotic-induced decreases in the bioactivity of these peptides may result in increased susceptibility to infectious pathogens. Disruption of these processes may play a part in amphibian mortality and subsequent population declines of amphibian species. The objective of this study was to investigate the effects of atrazine on larval development and the bioactivity of antimicrobial peptides collected from dermal secretions of the juvenile African clawed frog, Xenopus laevis. Atrazine is an environmental concern because it is commonly detected in surface water and has been shown to elicit developmental effects and immunosuppression in amphibians following laboratory exposures to relevant concentrations. In the present study, X. laevis larvae (NF stage 57-58) were exposed to atrazine (0.1, 1.0, 10, 100, and 1000 g/L) during critical developmental stages. Exposure to 1000 g/L resulted in a statistically significant increase in time required to complete metamorphosis (p=0.001). Upon completion of metamorphosis, electrically-stimulated secretions of bioactive peptides were collected from treated and control animals. The bioactivity of pooled samples was determined via a growth inhibition assay using Batrachochytrium dendrobatidis, a known amphibian pathogen. The findings from these studies attempt to discern the effects of atrazine on immunological and developmental aspects of an ecologically important species. Hence, the results of the current study signify the impact of atrazine on environmental quality.
Key words: atrazine, xenopus laevis, amphibians, antimicrobial peptides
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