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Fig. 5. Spatiotemporal expression of chd, gsc, and Xbra in early control and cycloheximide (CHX)-treated embryos. A: In control stage (st) 9 blastulae, chd is expressed in a large area on the prospective dorsal side. B: At the onset of gastrulation, the organizer region is stained. D,E: Early gsc staining
is detected in the dorsal vegetal–marginal region (D) and later in the organizer (E). G,H: Xbra transcripts also appear first in the dorsal marginal zone (G) and later mark the mesodermal ring (H). C,F,I: These early gastrula patterns are schematically illustrated in C,F, and I, respectively (lateral views). K,O,R: In CHX-treated embryos, the early chd, gsc, and Xbra expression domains are similar to the control. L,M: At stage 10 , however, the chd pattern resembles an slightly expanded stage 9 pattern. L: Note for example the chd-positive vegetal cells. M: The lateral–ventral regions of the animal
cap remain chd-negative. P: In stage 10.5 embryos, gsc is strongly expressed in the dorsal marginal zone, weaker staining can be seen in lateroventral
regions (left, curved arrows; vegetal view) and in the animal cap (right; animal view). S,T: At the same time, Xbra is expressed dorsally in the same
region. It appear slightly expanded animalward when compared with the blastula pattern, but strong signal is still confined to the dorsal side of the
embryo. S: Weak signal can be seen in lateral and in animal regions. S,T: Vegetal and ventral areas seem to be devoid of Xbra transcripts. N,Q,U: The
CHX-“gastrula” patterns are schematically illustrated in N, Q, and U, respectively (lateral views; dark blue, strong expression, light blue, weaker expression). Arrowheads indicate the endogenous expression sites, the arrows in B,E,H indicate the dorsal lip. an, animal; do, dorsal; lat, lateral; veg, vegetal; ven, ventral. |
