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. 2017 Jan 6;7:40056. doi: 10.1038/srep40056

Figure 1. Structure of the ovo gene and its expression during embryogenesis.

Figure 1

(a) Genomic organization of the ovo locus, which encodes three transcripts: ovo-A, ovo-B, and svb. Exons (boxes), introns (straight lines), protein coding regions (yellow boxes), and zinc-finger DNA-binding domains (orange boxes) are shown. Regions corresponding to the probes for in situ hybridization (purple bars) and the ovo-A– and ovo-B–specific region amplified by qRT-PCR analysis (blue and red bars, respectively) are also indicated. Sites where Egfp was inserted are indicated by green triangles. The ovoA-Nterm-egfp and ovoB-Nterm-egfp knock-in alleles contain the gene in the N-terminal regions of the Ovo-A and Ovo-B proteins, respectively. (b–e) Expression of ovo transcripts during embryogenesis. Probes used for in situ hybridization are indicated in (a). Embryos (b and d) and gonads (c and e) were hybridized with a common probe (b and c) and an svb-specific probe (d and e). Gonads (c and e) were double-stained for ovo or svb transcript (magenta) and Vasa protein (green), a marker for germ plasm and PGCs. The developmental stage of each embryo is shown in lower right. Arrowheads show germ plasm and PGCs. Scale bars: 20 μm. (f) The levels of ovo-A (blue) and ovo-B transcript (red) relative to the expression level of ovo-B in st.4 PGCs were determine by qRT-PCR, and plotted against the developmental stages of embryogenesis. Means ± SEM of three biological replicates are shown. (g–r) Expression of maternal and/or zygotic Ovo protein during embryogenesis. The Ovo-EGFP fusion protein encoded by ovoB-Nterm-egfp was detected using an anti-GFP antibody (green). Developmental stages are shown at lower right. Insets show close-up images of germ plasm and PGCs. Maternal and zygotic Ovo-EGFP protein was detected in embryos derived from females homozygous for ovoB-Nterm-egfp mated with males hemizygous for ovoB-Nterm-egfp (g–j). Maternal Ovo-EGFP was detected in embryos with YFP staining, derived from ovoB-Nterm-egfp/FM7c, Dfd-GMR-nvYFP females mated with y w males (k–n). Zygotic expression of Ovo-EGFP was detected in only female embryos produced from y w females mated with ovoB-Nterm-egfp hemizygous males, since the ovo gene is on X chromosome. Scale bars: 20 μm.