title: Genetics and timing of sex determination in the East African cichlid fish Astatotilapia burtoni.
abstract: BACKGROUND
  The factors determining sex are diverse in vertebrates and especially so in teleost fishes. Only a handful of master sex-determining genes have been identified, however great efforts have been undertaken to characterize the subsequent genetic network of sex differentiation in various organisms. East African cichlids offer an ideal model system to study the complexity of sexual development, since many different sex-determining mechanisms occur in closely related species of this fish family. Here, we investigated the sex-determining system and gene expression profiles during male development of Astatotilapia burtoni, a member of the rapidly radiating and exceptionally species-rich haplochromine lineage.
  
  
  RESULTS
  Crossing experiments with hormonally sex-reversed fish provided evidence for an XX-XY sex determination system in A. burtoni. Resultant all-male broods were used to assess gene expression patterns throughout development of a set of candidate genes, previously characterized in adult cichlids only.
  
  
  CONCLUSIONS
  We could identify the onset of gonad sexual differentiation at 11-12 dpf. The expression profiles identified wnt4B and wt1A as the earliest gonad markers in A. burtoni. Furthermore we identified late testis genes (cyp19a1A, gsdf, dmrt1 and gata4), and brain markers (ctnnb1A, ctnnb1B, dax1A, foxl2, foxl3, nanos1A, nanos1B, rspo1, sf-1, sox9A and sox9B).
authors.affiliation: Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland. co.heule@unibas.ch.
authors.forename: Corina
authors.initials: C
authors.lastname: Heule
authors.affiliation: Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland. c.goeppert@stud.unibas.ch.
authors.forename: Carolin
authors.initials: C
authors.lastname: Göppert
authors.affiliation: Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland. walter.salzburger@unibas.ch.
authors.forename: Walter
authors.initials: W
authors.lastname: Salzburger
authors.affiliation: Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland. astrid.boehne@unibas.ch.
authors.forename: Astrid
authors.initials: A
authors.lastname: Böhne
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D023681:Cichlids / Q000235:genetics* / Q000378:metabolism; D005260:Female; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D053263:Gene Regulatory Networks; D005819:Genetic Markers; D008297:Male; D009928:Organ Specificity; D019849:Sex Determination Processes; D012733:Sex Differentiation; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome
chemical_list: D029941:Fish Proteins; D005819:Genetic Markers; D014157:Transcription Factors