Identification and expression of the ecdysone receptor in the harpacticoid copepod, Amphiascus tenuiremis, in response to fipronil.

Abstract

The marine copepod, Amphiascus tenuiremis (A. tenuiremis), is a well characterized invertebrate model for the screening and evaluation of endocrine and reproductive toxins using life-cycle assays. These tests evaluate phenotypic endpoints related to development and reproduction, which are utilized to predict population outcomes. Some of these endpoints in arthropods, including sexual maturation and molting, are controlled by the hormone ecdysone which acts through its cognate receptor, the ecdysone receptor. The purpose of this research was to obtain and characterize sequence information for the A. tenuiremis ecdysone receptor and investigate modulation of expression levels by fipronil, an insecticide that causes infertility in males and reduced egg extrusion in female copepods, and ponasterone, a natural ecdysone receptor agonist. Results show successful cloning and phylogenetic analysis of the ecdysone receptor for A. tenuiremis, providing the first genetic information for a hormone receptor in this species. Exposure of copepodites to fipronil for 1, 2, 4, 18 and 30 h caused a significant increase in ecdysone receptor transcriptional expression at 30 h compared to control unexposed animals. This work illustrates a potential mechanism whereby exposure to fipronil, and potentially other endocrine disrupting compounds, results in impacted reproduction. Furthermore, this exemplifies the potential utility of ecdysone receptor transcriptional measurement as a sensitive and rapid biomarker of ecological relevance when linked to traditional A. tenuiremis bioassays.

• Authors: Karin Gaertner, G Thomas Chandler, Joseph Quattro, P Lee Ferguson, Tara Sabo-Attwood
• Journal: Ecotoxicology and environmental safety (Ecotoxicol Environ Saf) Vol. 76 Issue 2 Pg. 39-45 (Feb 2012) ISSN: 1090-2414 [Electronic] Netherlands
• PMID: 22000904 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: Copyright © 2011 Elsevier Inc. All rights reserved.

Chemical References

• Biomarkers
• Endocrine Disruptors
• Insecticides
• Pyrazoles
• Receptors, Steroid
• ecdysone receptor
• Ecdysone
• fipronil

Topics

• Amino Acid Sequence
• Animals
• Biological Assay
• Biomarkers (metabolism)
• Copepoda (drug effects, genetics, metabolism)
• Ecdysone (metabolism)
• Endocrine Disruptors (toxicity)
• Environmental Monitoring
• Female
• Insecticides (toxicity)
• Life Cycle Stages
• Male
• Molecular Sequence Data
• Pyrazoles (toxicity)
• Receptors, Steroid (metabolism)
• Reproduction (drug effects)