Expression of Chironomus riparius serine-type endopeptidase gene under di-(2-ethylhexyl)-phthalate (DEHP) exposure

Abstract

Environmental stressors can induce changes in gene expression that can be useful as biomarkers. To identify potential biomarkers of water quality, we characterized full-length cDNA sequences of the serine-type endopeptidase (SP) gene from Chironomus riparius. Their expression was analyzed during different life-history stages and in response to treatment with various concentrations of di(2-ethylhexyl) phthalate (DEHP) for short and long periods of time. A comparative molecular and phylogenetic investigation was then conducted among different orders of insects using sequence database analysis. The sequence of the C riparius SP gene was found to be most closely related to the sequence of SPs isolated from Aedes aegypti. In addition, the basal level of C riparius SP mRNA was more highly expressed in larvae than in other life-history stages. However, the expression of C riparius SP was primarily limited to the gut in larvae. When the effects of short-term exposure to DEHP were evaluated, C riparius SP gene expression decreased within 1 h of treatment, regardless of dose. We also investigated expression of the C riparius SP gene following long-term DEHP exposure (10 days) and found that it decreased significantly across all DEHP dosages. Finally, the response of the SP gene was more sensitive in C riparius that were exposed to low concentrations of DEHP than in those that were exposed to high concentrations. These results show that suppression of the C riparius SP gene by DEHP is as a potential biomarker that could be useful for monitoring aquatic quality. (C) 2008 Elsevier Inc. All rights reserved.