Molecular basis of gender and reproductive status in breeding zebrafish

Sexual reproduction is a complex process involving multiple pathways. In this study, we aimed at investigating gene expression profiles underlying gender specificity in the zebrafish. To do so, we analyzed the transcriptome of the gonads of breeding fish and queried the gene expression profiles for significant differences between the genders and also between stages of gonad development. Major differences in gene expression profiles between genders were encountered at the level of the gonads. In addition, we identified biological processes associated with stage of sexual development in female gonads. Keywords: gender and stage related gene expression Sexually mature fish (6 males and 6 females) were kept in a 15L tank and allowed to breed naturally. After a 20-day period, fish were sacrificed humanly and one of the gonads were extracted, fixed in RNAlater (Ambion) and stored at -20oC until required for microarray analysis. The remaining gonad was fixed in Bouins for histological analysis of the gender and reproductive stage. RNA was extracted using the TRI reagent method followed by a LiCl precipitation (Sigma) according to the manufacturer's instructions. Total RNA was amplified and labeled using the Amino Allyl MessageAmp aRNA amplification kit (Ambion). A reference design was used for the array hybridizations. Array analysis was performed according to established protocols (described in Santos et al., 2006) and the data was extracted and queried for differences in gene expression profiles between genders and also between individuals within a gender and correlated with the histological characteristics of the gonads.