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Figure 5. Expression of accessory genes in chick and Xenopus. We examined the expression of several genes that, although not strictly ion pumps or channels, are relevant to maintaining a cell's membrane potential. The 14-3-3 family member ϵ is weakly expressed in the primitive streak in chick embryos at stage (st.) 3 (arrow, A), but by st. 4, its expression is extremely strong in all embryonic tissues (red arrow, B), except for the posterior-most margin of the area opaca (yellow arrow, B). C: The 14-3-3 α/β is expressed in the primitive streak at st. 3 (red arrowhead) but is specifically excluded from Hensen's node (white arrowhead). D,E: Aquaporin 7 mRNA is present around the circumference of the embryo at st. 7 (red arrows) but is not detected in the yolky vegetal cells. D: The inside view of a st. 7 embryo split in half parallel to the animalegetal axis after in situ hybridization. E: At somite stages, Aquaporin 7 is detected (red arrowheads) in the brain, eye, branchial arches, and somites. F: Aquaporin 4 is detected (red arrowheads) in the cortex of the animal portion of the embryo at the two-cell stage. F: The interior view of half of a two-cell embryo; the blastomeres were separated manually after in situ hybridization. G: By the four-cell stage, the mRNA is detected only in the nucleus. H: By somite stages, Aquaporin 4 can be detected in the brain, somites, and tail bud. In early chick embryos, hensin is expressed in the base of the primitive streak at st. 3 (arrowhead, I) and then in stripes in the lateral plate of head-fold stage embryos (arrows, J). KCHIP4.2 is not detected in the early chick (arrow, K), but KCHIP2 is expressed in the primitive streak (arrow, L). Red arrows indicate regions of expression. |
