Gene expression rhythms in rainbow darter male (Etheostoma caeruleum) across an annual reproductive cycle

We have been studying intersex in male rainbow darter (Etheostoma caeruleum) associated with exposure to sewage effluents. To understand changes in the gene transcriptome associated with intersex it was necessary to have a better understanding of normal annual changes in the transcriptome. The goal of this research is to identify patterns of gene expression associated with the different stages of gonad development during the annual cycle. The studies of molecular pathways involve in ovarian or testis development has been poorly studied. While most studies focus on female ovarian changes, there is a gap in understanding testis development. A customized second generation microarray for rainbow darter (8x15k) was used to identify patterns of gene expression -in terms of mRNA abundance- in male rainbow darter gonads during an annual cycle. Rainbow darter males were collected on field work surveys in May (spawning), August (post-spawning), and October (recrudescence) 2011, and January (developing) and March (pre-spawning) 2012, using a back pack electrofisher from a clean area at the Grand River, ON, Canada.