Developmental expression of LPXRFa, kisspeptin, and their receptor mRNAs in the half-smooth tongue sole Cynoglossus semilaevis

Both gonadotropin-inhibitory hormone (GnIH) and kisspeptin play a critical role in the control of reproduction in vertebrates. However, the spatial–temporal expression patterns and possible roles of these two peptides during development are poorly understood. To this end, we evaluated dynamic expression profiles of lpxrfa, the piscine ortholog of gnih, kisspeptin (kiss2) and their receptor mRNAs during embryogenesis and early larval development in a flatfish, Cynoglossus semilaevis. Quantitative RT-PCR analysis indicated that both ligand (lpxrfa and kiss2) and receptor (lpxrfa-r and kiss2r) mRNAs were detected in unfertilized eggs and during embryogenesis, but with different expression profiles. In addition, lpxrfa-r, kiss2 and kiss2r transcripts increased significantly at 6 days post-hatching (dph), while lpxrfa mRNAs did not vary significantly during all larval development. Taken together, these results of the present study suggest that both LPXRFa and kisspeptin systems could be functional and play differential roles during embryogenesis and early larval development in tongue sole.