Germ cells are required to maintain a stable sexual phenotype in adult zebrafish

• Published in: Developmental biology 2013-04, Vol.376 (1), p.43-50
• Main Authors: Dranow, Daniel B., Tucker, Richard P., Draper, Bruce W.
• Format: Article
• Language: English
• Subjects: adults; Animals; Base Sequence; Cloning, Molecular; Danio rerio; Female; females; gene expression; Gene Expression Regulation - physiology; Germ cells; Germ Cells - cytology; Germ Cells - metabolism; Histological Techniques; Immunohistochemistry; In Situ Hybridization; loci; Male; males; Metronidazole; Models, Biological; Molecular Sequence Data; Oocyte; oocytes; Phenotype; Plasmids - genetics; Sex determination; Sex Determination Processes - physiology; Signal Transduction - physiology; stem cells; Stem Cells - cytology; Stem Cells - metabolism; Zebrafish - embryology
• ISSN: 0012-1606; 1095-564X
• DOI: 10.1016/j.ydbio.2013.01.016

Sex in zebrafish is not determined by a major chromosomal locus, but instead relies on a mechanism that is influenced by a germ cell-derived signal, as animals that lack germ cells, or specifically oocytes, develop as phenotypic males. These data suggest that during primary sex determination, an oocyte-derived signal acts on the bipotential somatic gonad to promote the female-specific program. However, it is not known if germ cells are required only during the primary sex-determining window, or if they are required throughout adult life to maintain the female sexual phenotype. Here, we show that while wild-type zebrafish do not switch sex as adults, germ cell-depleted adult females readily convert to a male phenotype. Notably, when oocytes are depleted, but germline stem cells remain, adult females sex-revert to sperm-producing males, indicating that a germ cell-derived signal acts on the somatic gonad to promote female development directly or indirectly by repressing male-specific gene expression. These results also confirm that signals from the somatic gonad in turn ensure that the sex appropriate gamete is produced. ► Germ cell depletion in adult zebrafish females leads to sex reversal. ► Sex reversed fish are both phenotypically and behaviorally male. ► Partial germ cell depletion in adult female fish results in fertile males. ► Role of germ cells in maintaining female sex may be conserved in teleost fish.