September 1, 2002;
Sequence and expression of FoxB2 (XFD-5) and FoxI1c (XFD-10) in Xenopus embryogenesis.
We report on the temporal and spatial expression pattern of two novel genes of the Xenopus fork head/winged helix family, xFoxB2
and xFoxI1c. xFoxB2
is activated at the late blastula
stage and first expressed within the dorsolateral ectoderm
except for the organiser territory. During gastrulation, xFoxB2
is found in two ectodermal stripes adjacent to the dorsal midline. Expression is completely down-regulated during neurulation. However, two distinct sets of cells expressing xFoxB2
re-appear in the rhombencephalon
of swimming tadpoles. xFoxI1c is initially expressed at the early neurula
stage in an epidermal ring around the neural field. Subsequent expression is found to be increased, and is exclusively localised to placodal precursor cells. The placodal expression remains until stage 40, when it is restricted to a distinct region in the lateral
body wall behind the gills.
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Fig. 3. Spatial expression of xFoxB2. Whole mount in situ hybridisation was performed with xFoxB2 and xFoxB1 (G, L) antisense probes and embryos at different developmental stages. (A) Stage 11; (B) parasagittal section of A; (C) stage 12; (D) stage 14; (E) transversal section of D, nuclei stained with DAPI; (F) stage 15; (G) FoxB1 (Fkh-5), stage 16; (H) stage 35; (I) horizontal section of H; (J) stage 41; (K) horizontal section of J; (L) FoxB1, stage 41. Embryos shown in (A–C) are orientated with dorsal side to the right and animal half to the top; D, F, G anterior view; H shows a lateral and J as well as L a dorsal view. The plane of sections is marked by red lines. cg, cement gland; dl, dorsal lip; ey, eye; np, neural plate; no, notochord; ov, otic vesicle; rh, rhombencephalon.
Fig. 4. Spatial expression of xFoxI1c. The spatial pattern of xFoxI1c expression was determined by whole mount in situ hybridisation and compared to the early expression patterns of FoxI1a/b and Sox3. (A) Stage 14; (B) stage 17; (C) horizontal section of B, the insert shows part of the epidermal layer stained with DAPI to show the nuclei; (D) stage 22; (E) stage 28; (F) horizontal section of E; (G) stage 32, (H) stage 41; (I) horizontal section of H. Embryos in A and B are shown in anterior view, D–H are lateral view, plane of sections are marked by red lines. J, K and L show stage 11 embryos hybridised with probes as indicated; all are orientated with dorsal side to the right and the animal half to the top. np, neural plate; 1.ba, first branchial arch; cg, cement gland; ey, eye; gi, gills; np, neural plate.
foxb2 (forkhead box B2), gene expression in Xenopus laevis embryo, assayed via in situ hybridization, NF stage 41, dorsal view, anterior right.
Fig. 2. Temporal expression of xFoxB2 and xFoxI1c during embryogenesis. RT-PCR was performed with RNA of different developmental stages using primers for FoxB2, FoxI1c and FoxI1a. Histone H4 was used as an internal control, staging was done according to Nieuwkoop and Faber (1967).