This study points out new lncRNAs, sex-specific orgonad-specific: the four sex-differentiating genes studied ([i]SOX9, SOX10, FOXL2 and WNT4[/i]) share a [b]bidirectional promoter[/b] with a lncRNA. In the literature, it is described that pervasive transcription around a promoter region could act as a [b]reservoir of RNA polymeraseII[/b], or serve as [b]a barrier to block the spread of repressive chromatin [3].[/b] It is also admitted that non-coding transcripts can influence protein-coding gene expression by reorganizing chromatin structure and recruiting transcriptional co-factors. In our opinion, these lncRNAs transcriptional activity is a way to keep the promoter open and avoid stochastic variation in the expression of the corresponding proten-coding genes. Indeed, in a 60 dpc-fetal gonad, a small variation in sex-differentiating genes expression could lead to developmental sex-disorders like sex-reversal, as it is observed in goats [b][1][/b]. The aim of this work is two-fold. First, to list all the genes that share a bidirectional promotor in order to characterize different protein classes. Second, it aspires to identify all lncRNAs involved intesticular or ovarian differentiation.Using bio-informatics and differential analyses, we want (1) to discriminate ovary-specific from testis-specific lncRNAs and (2) to determine gonad-specific lncRNAs as against PBMC. Then, the comparison of the lncRNAs identified with neighbouring proteine-coding genes will let us highlight new regulatory elements necessary for sex-differentiating genes expression. [u]REFERENCES[/u]: [b][1][/b] Pailhoux [i]et al.[/i], 2001. [i]A 11.7kb-deletion triggers intersexuality and polledness in goats.[/i] Nature Genetics. [b][2][/b] Pannetier [i]et al.[/i], 2012. [i]Telling the story of XX sex-reversal in the goat: Highlighting the sex-crossroad in domestic mammals.[/i] Sexual Development. [b][3][/b] Wei [i]et al.[/i], 2011. [i]Functional consequeces of bidirectional promoters.[/i] Cell