Water Resources Research Act Program

Details for Project ID 2013NJ340B

Effect of cadmium on accelerated metamorphosis induced by hormesis in larvae of Chironomus riparius (Diptera:Chironomidae)

Institute: New Jersey
Year Established: 2013 Start Date: 2013-03-01 End Date: 2014-02-28
Total Federal Funds: $5,000 Total Non-Federal Funds: $10,000

Principal Investigators: Jun Oh, Carolyn Bentivegna

Abstract: The purpose of this proposed study is to address novel and integrative research approaches on assessing ecological issues, focusing on freshwater of New Jersey impacted by anthropogenic activities. Larvae of Chironomidae (chironomid) are a convenient animal model for studying aquatic ecology. Previously, protein profiles of chironomids exposed to varying cadmium (Cd) concentrations were generated by separating the protein mixtures in hemolymph on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), according to their molecular weight (MW). At low Cd (0.3M) exposure, an increased intensity of low MW bands (< 7kDa) was observed, while a decreased intensity was observed at higher concentrations (≥3.0M). Liquid chromatography-mass spectrometry (LC-MS) analysis indicated that the most abundant proteins in the bands tested (4-17kDa) were isomers of Hb proteins. The low MW (<7kDa) proteins represented fragments of the major Hb proteins and were probably degradation products. Our hypothesis is that the increased intensity of low MW bands at low Cd concentrations was due to hormetic enhanced growth associated with degradation of Hb proteins and accelerated metamorphosis. This mechanism is potentially controlled by ecdysone – a steroid hormone responsible for pupation, and by ubiquitin (Ub) – a highly conserved gene responsible for protein turnover. This will be tested by comparing the responses of ecdysone receptor (EcR), Ub, and Hb IV/VII genes in 4th instar Chironomus riparius upon exposure to Cd using quantitative polymerase-chain-reaction (q-PCR). Results might establish a novel molecular mechanism for hormesis and further develop Hb profiles as a bio-monitoring tool.