Fig. 3
Blocking Embryonic Bmp Signaling Postpatterning of the Embryonic Axis Inhibits Myelopoiesis (A–D) Expression of pu.1 was lost in the anterior myeloid pool in embryos from a heat shock-inducible dominant-negative Bmp receptor transgenic line, after heat shock (HS) at 70% epiboly and bud stages. GFP-negative siblings (top) and GFP-positive siblings (bottom) (dorsal views displaying ALPM) were produced from a heterozygous outcross of the heat shock-inducible truncated Bmp receptor-GFP transgenic fish, all at 14–16 somites. (A) 70% epiboly heat shock (n = 63 GFP-negative embryos all expressed pu.1, n = 60/74 GFP-positive embryos displayed vastly reduced pu.1 expression). (B) Bud stage heat shock (n = 155 GFP-negative embryos all displayed pu.1 expression, n = 117/119 GFP-positive embryos displayed vastly reduced pu.1 expression). (C) 4 somites heat shock (n = 54 GFP-negative embryos displayed normal pu.1 expression, n = 45/77 GFP-positive embryos displayed only mildly reduced pu.1 expression). (D) 12 somites heat shock (n = 52 GFP-negative embryos all displayed pu.1 expression, n = 43 GFP-positive embryos all displayed normal pu.1 expression). (E–H) Transgenic animals heat shocked at bud stage phenocopy lost-a-fin expression of pu.1. In lost-a-fin mutants (F), anterior pu.1 expression is vastly reduced compared with wild-type (E), while posterior pu.1 shows no obvious reduction at 16 hpf. Likewise, in GFP-positive embryos from bud stage heat shocks (H) anterior pu.1 expression is vastly reduced compared to heat shocked GFP-negative siblings (G), while posterior pu.1 expression shows no obvious reduction at 14 hpf. Dorsal views of whole embryos. (I and J) Expression of scl is retained in the anterior and posterior in both GFP-negative ([I], n = 98) and GFP-positive ([J], n = 87) embryos after heat shock at bud stage. Dorsal views of whole embryos. |