Meeting Abstract
Polybrominated diphenyl ethers (PBDEs) are environmentally pervasive flame retardants that have been linked with endocrine disruption in a variety of organisms. In crustaceans, recent studies have demonstrated a molt-inhibiting effect by BDE-47, but little is known about the specific mechanism through which molt-inhibition occurs. This study examined whether the inhibitory effects arise from the disruption of hormone signaling in the epidermis using Callinectes sapidus. First, we partially sequenced epidermal cDNA of N-acetyl-β-glucosaminidase (NAG), a terminal enzyme in the ecdysteroid-signaling cascades. This partial cDNA sequence was then used to create primers for quantifying NAG gene expression. A new tissue culture technique was developed, wherein epidermal tissue and the overlying exoskeleton were immersed in a medium of a physiologically relevant osmolarity. Using this method, the inducibility of NAG by 20-hydroxyecdysone (20-HE) was assessed in vitro. Exposures to 1 µM 20-HE were found to significantly induce NAG expression. Using NAG gene expression as a biomarker for ecdysteroid signaling, the effects of BDE-47 were measured. NAG gene expression increased for exposure to a combination of 1 μM BDE-47 and 1 μM 20-HE. This trend of increasing NAG expression in the binary BDE-47 exposure as compared to individual exposures of these chemicals is suggestive of a synergistic effect on epidermal expression of NAG mRNA. Our findings contribute to a better understanding of the effects of PBDE contamination and mechanisms for the disruption of molting in crustaceans by BDE-47.
