Figure 8

Enhancement of morphant brain phenotypes by injection of paralogous RNA corroborates genetic antagonism between brd2a and brd2b. Rescue-Enhancement studies using zebrafish brd2a and brd2b-L in vitro-synthesized RNAs (rather than human Brd2) were used to test functional antagonism between paralogs implied by double knockdown suppression. Panels (A?I): Brightfield images of representative 24 hpf prim 5 embryos from indicated treatment groups. For controls: (A) uninjected wild type, (B) brd2aRNA-injected, and (C) brd2b-LRNA-injected. For brd2bMO rescue-enhancement: (D) brd2bMO-injected, (E) brd 2bMO + brd2b-LRNA co-injected (rescue), and (F) brd2bMO + brd2aRNA co-injection (enhancement). For brd2aMO rescue-enhancement: (G) brd2aMO-injected, (H) brd2aMO + brd2aRNA co-injected (rescue), and (I) brd2aMO + brd2b-LRNA co-injection (enhancement). Arrows indicate rescue (E,H) and enhancement (F,I) of morphant brain defects by co-injection of cognate or paralogous RNA, respectively. See Table 2 for population morphology data. Panels (J?R): Darkfield images of representative 24 hpf prim 5 embryos from the same treatment groups after TUNEL assay: (J) uninjected wildtype, (K) brd2aRNA-injected, and (L) brd2b-LRNA-injected; (M) brd2bMO-injected, (N) brd2bMO + brd2b-LRNA co-injected (rescue), and (O) brd2bMO + brd2aRNA co-injection (enhancement); (P) brd2aMO-injected, (Q) brd2aMO + brd2aRNA co-injected (rescue), and (R) brd2aMO + brd2bRNA co-injection (enhancement). Note rescue (N,Q) and enhancement (O,R) of morphant excess apoptosis by co-injection of cognate or paralogous RNA, respectively, supporting the idea of functional antagonism between paralogs. See Figure 5 for quantitative TUNEL data.