A cDNA microarray for the three-spined stickleback, Gasterosteus aculeatus L., and analysis of the interactive effects of oestradiol and dibenzanthracene exposures

The stickleback is a useful model species for aquatic toxicology and endocrinology and with the recent sequencing of its genome, ecotoxicogenomics. The effects of treatment on male and female sticklebacks with the polycyclic aromatic hydrocarbon (PAH), dibenzanthracene (DbA), the female hormone, 17 beta-oestradiol (E2) and a binary mixture of the two were investigated. Quantitative RT-PCR assays were carried out for cytochrome P450 1A (cyp1A), vitellogenin (VTG) and oestrogen receptor alpha, and cyp1A enzyme activity was assessed by measurement of ethoxyresorufin-o-deethylase (EROD) activity , VTG and spiggin protein by enzyme-linked immunosorbent assay. A stickleback cDNA microarray consisting of 9692 clones was developed and used to assess gene expression responses to the treatments. Induction of cyp1A mRNA and EROD activity was seen in both sexes in response to DbA and a further induction of cyp1A found with the binary treatment. VTG mRNA was induced in male fish exposed to E2 and the binary mixture, while for females, statistically significant induction was seen only with the binary mixture. Similar behaviour was found with zona pellucida and chorion protein mRNA using the microarray. ER alpha mRNA was induced with E2 and the binary mixture in both sexes. The microarray showed additional transcripts that were differentially regulated by these treatments, which provide novel candidates for biomarker development and mechanistic studies. (C) 2008 The Authors Journal compilation (C) 2008 The Fisheries Society of the British Isles.