title: Elevated amh gene expression in the brain of male tilapia (Oreochromis niloticus) during testis differentiation.
abstract: Anti-müllerian hormone (AMH) is expressed in male embryos and represses development of müllerian ducts during testis differentiation in mammals, birds and reptiles. Amh orthologues have been identified in teleosts despite them lacking müllerian ducts. Previously we found sexually dimorphic aromatase activity in tilapia brains before ovarian differentiation. This prompted us to search for further dimorphisms in tilapia brains during sex differentiation and see whether amh is expressed. We cloned the tilapia amh gene and found that it contains 7 exons but no spliced forms. The putative protein presents highest homologies with Amh proteins of pejerrey and medaka as compared to other Perciformes. We analysed amh expression in adult tissues and found elevated levels in testes, ovary and brain. Amh expression was dimorphic with higher levels in XY male brains at 10-15 dpf, when the gonads were still undifferentiated and gonadal amh was not dimorphic. Male brains had 2.7-fold higher amh expression than gonads. Thereafter, amh levels decreased in the brain while they were up-regulated in differentiating testes. Our study indicates that amh is transcribed in male brains already at 10 dpf, suggesting that sexual differentiation may be occurring earlier in tilapia brain than in gonads.
authors.affiliation: Aquaculture Research Unit, CIRAD-PERSYST, Institut des Sciences de l'Evolution, CNRS, Université Montpellier 2, Montpellier, France.
authors.forename: S
authors.initials: S
authors.lastname: Poonlaphdecha
authors.forename: E
authors.initials: E
authors.lastname: Pepey
authors.forename: S-H
authors.initials: SH
authors.lastname: Huang
authors.forename: M
authors.initials: M
authors.lastname: Canonne
authors.forename: L
authors.initials: L
authors.lastname: Soler
authors.forename: S
authors.initials: S
authors.lastname: Mortaji
authors.forename: S
authors.initials: S
authors.lastname: Morand
authors.forename: F
authors.initials: F
authors.lastname: Pfennig
authors.forename: C
authors.initials: C
authors.lastname: Mélard
authors.forename: J F
authors.initials: JF
authors.lastname: Baroiller
authors.forename: H
authors.initials: H
authors.lastname: D'Cotta
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D054304:Anti-Mullerian Hormone / Q000235:genetics*; D001141:Aromatase / Q000378:metabolism; D001483:Base Sequence; D001921:Brain / Q000254:growth & development / Q000378:metabolism; D023681:Cichlids / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D005260:Female; D029941:Fish Proteins / Q000235:genetics*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012733:Sex Differentiation / Q000235:genetics*; D013737:Testis / Q000254:growth & development* / Q000378:metabolism
chemical_list: D017931:DNA Primers; D029941:Fish Proteins; D012333:RNA, Messenger; D054304:Anti-Mullerian Hormone; D001141:Aromatase