Fig. 8

Myosin regulatory light chains 9a and 9b are required for definitive hematopoiesis.

(A) In situ hybridizations of 48 hpf embryos. Left panels, whole mount; right panel, transversal section. a, aorta; n, notochord; nt, neural tube; s, somites; v, vein; ye, yolk extension; ys, yolk sac. Results were obtained from four independent experiments. Note that for the 25/125 embryos in the top panel, the myl9a signal in the aorta was weaker and masked by the somitic staining. (B,C) Maximum projection of Z-planes obtained from 48 hpf Tg(CD41:eGFP) embryos, focusing either on the AGM region (B), or on the CHT (C). Scales bars, 50 μm (B); 100 μm (C). Only the CD41:eGFP⁺ cells above the yellow dashed line were counted (C), as those beneath are not necessarily hematopoietic cells (Kissa et al., 2008). (D,E) Effect of myl9a and myl9b morpholinos (e2i2 and e3i3, respectively, see Materials and methods for details and Figure 8—figure supplement 1) based knockdown on the number of CD41:eGFP⁺ cells in the AGM (D) and the CHT (E). Similar results, in the AGM and in the CHT, were obtained at lower quantities of morpholinos (see Figure 8—figure supplement 2). n = indicate the numbers of embryos. (B, E, F) Error bars represent mean values ± SEM. Unpaired t test (**) p<0.01; (***) p<0.001.