Fig. 1

Expression patterns of hspb7 and hspb12 during the first 22 h of development. (A) hspb7 was first detected by in situ hybridization at 5.7 hpf in the yolk syncitial layer (YSL) (B) hspb7 expression continued in the YSL and was transiently expressed in the forming Kupffer′s vesicle (KV) at the tailbud-1 somite stage. (C) Posterior view of hspb7 expression in KV (arrow) at tailbud stage (dorsal to the left). (D) hspb7 disappeared from KV (arrow) by the four somite stage but remained in the YSL. (E) hspb12 was similarly expressed in the YSL at 5.7 hpf. (F) hspb12 was expressed in the YSL at 1-somite stage, but was not detected within KV. (G) Posterior view showing that hspb12 hybridization was not visible in KV. The surface of the YSL is depressed beneath the tailbud. This causes an edge-on view of the YSL surface, but the apparent staining was not visible at other angles. (H) hspb12 was absent from KV in four somite stage embryos, but YSL expression continued until approximately the 10 somite stage. (I) hspb7 was expressed in the bilateral heart fields beginning at the 12 somite stage. (J) hspb7 in the heart field and somites at the 18 somite stage. (K) hspb12 expression began in the bilateral cardiac precursors at the 18 somite stage. (L) Nkx-2.5 is expressed in ventricular precursors and corresponds to the expression sites of hspb7 and hspb12 at 18 somites. (M) hspb7 and (N) hspb12 were expressed in the fused heart fields as the leftward jog of the primitive heart tube begins at 21 somites. (O) Expression of myl7 (cmlc2) at 21-22 somites overlapped hspb7 and hspb12 hybridization.