Fig. 1

Dmrt1 expression in zebrafish gonads. A-C) Expression of dmrt1 by in situ hybridization on sections of adult gonads. A) In adult ovaries, dmrt1 expression was observed primarily in stage Ib oocytes; staging according to Selman et al. ( Selman et al., 1993). B) Adult testis had dmrt1 expression in nearly all stages of spermatogenesis, except spermatozoa (sz). C) In testis devoid of germ cells (∅ germ line (gl)), dmrt1 was detected primarily in cells lining the testis tubules, indicative of Sertoli cell expression. D-F) Whole mount in situ hybridization on gonads from 5 weeks post fertilization (wpf) fish. D) Dmrt1 was not detected in gonads with ovarian morphology as judged by presence of many early stage oocytes (inset shows an early stage oocyte). E-F) Dmrt1 expression was detected in gonads that morphologically resembled testes (E) and in gonads devoid of germ cells (F). G) RT-PCR on gonadal tissue at 7 wpf, 11 wpf and 28 wpf. At 7 wpf, gonads could not easily be distinguished as ovary or testis during tissue harvesting, therefore, all gonads were mixed at this stage. By 11 wpf, dissected gonads were chosen that resembled either ovaries or testis as judged by morphology during dissection. RT-PCR was also performed on gonads that lacked germ cells (∅ gl) to detect expression in somatic tissues. RT-PCR for the ziwi transcript demonstrated that germ cells were present in intact gonads but absent from germ cell depleted gonads (∅ gl) at all ages (shown for 7 wpf and 11 wpf). Dmrt1 expression was detected by RT-PCR in all samples. Control RT-PCR samples (ctrl) were samples where no reverse-transcriptase was added to the reaction. For 28 wpf samples, two independent samples were run for each: each ovary sample was derived from a single individual while each testes sample contained testes from 4 or more individuals. RT-PCR results for these 28 wpf samples for ziwi and b-actin were previously published ( Siegfried and Nüsslein-Volhard, 2008). scale bars =50 µm.