Identification of the Udu gene. (A) The udu gene is mapped to LG16 within the region covered by 3 BACs, zC196P10, zK7E18, and zC113G11. The number in red represents the number of the recombinants over 5864 meiosis events for each SSLP marker. Sequence analysis confirms that the udu mutation is situated in the BAC zC196P10. (B) The udu gene consists of 31 exons (solid box) and encodes a protein of 2055 aa. Both Udu^tu24 and Udu^sq1 harbor a nonsense mutation in exons 12 and 21, respectively. (C-F) WISH of band3 expression of 22-hpf wild-type embryo (C), Udu^sq1−/− embryo (D), Udu^sq1−/− embryo injected with in vitro synthesized wild-type udu (udu-wt) RNA (E), and Udu^sq1−/− embryo injected with in vitro–synthesized T2976A mutant (udu-T2976A) RNA (F). (G-J) band3 (G-H) and βe3-globin (I-J) expression by WISH in the 22-hpf control morphants (G,I), and MO-udu-2 morphants (H,J). In panels C to J, embryos are in lateral views with anterior to the left.