Semi-quantitative RT-PCR analysis of Ovex1 expression in chicken tissues. (A) Expression of Ovex1 in 8-day embryo tissues. RT-PCR was performed with pairs of primers designed to amplify specifically the unspliced mRNA (GagPol) or the spliced transcript (ORF3). Amplification of GAPDH transcripts was used as control for mRNA amounts. Primers and RT-PCR conditions are given in additional file 9 (Table S1, Primers and PCR conditions). A similar pattern of expression is observed in both cases. The level of transcripts is higher in the left ovary than in the right one and in the left testis. Expression is null in the right testis and in the other tissues tested, but for occasional traces in the wing. (B) Expression of Ovex1 in chicken gonads, as a function of age. The unspliced and spliced mRNAs were amplified from 8- and 12-day embryo left (L) or right (R) gonads, from 18-day embryo left gonads, and from adult (7 weeks) left ovaries or mixed (LR) testes. The identity of the RT-PCR amplified product was verified by sequencing. A control with chicken genomic DNA was performed in order to verify the absence of the deleted form in the genome and the specificity of amplification. The level of both types of mRNAs is up-regulated in the left ovary, weak in the right one, down-regulated after 8 days in the left testis, and null in the right one.