Details

Autor(en) / Beteiligte

• Kondo, Mariko
• Nanda, Indrajit
• Hornung, Ute
• Schmid, Michael
• Schartl, Manfred

Titel

Evolutionary Origin of the Medaka Y Chromosome

Ist Teil von

• Current biology, 2004-09, Vol.14 (18), p.1664-1669

Ort / Verlag

England: Elsevier Inc

Erscheinungsjahr

2004

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• Genetic sex determination in an XX-XY chromosome system can be realized through a locus on the Y chromosome that makes the undifferentiated gonad develop into a testis. Although this mechanism is widespread, only in two cases so far have the corresponding master male sex-determining genes been identified. One is Sry [1–5], which initiates testes determination in most mammals. The other is dmrt1bY [6, 7] (syn. dmy), from the fish medaka, Oryzias latipes. The mammalian Y is roughly estimated to be over 200 million years old [8]. The medaka Y may be considerably younger [6, 9]. A comparative analysis of the genus Oryzias revealed that one sister species of the medaka has dmrt1bY on a homologous Y chromosome, whereas in another closely related species only a non-sex-linked pseudogene is present. In all other species, dmrt1bY was not detected. The divergence time for the different species was determined with mitochondrial DNA sequences. The timing was confirmed by independent calculations based on dmrt1 sequences. We show that the medaka sex-determining gene originated approximately 10 million years ago. This makes dmrt1bY and the corresponding Y chromosome the youngest male sex-determining system, at least in vertebrates, known so far.