XB-IMG-44400
Xenbase Image ID: 44400
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Figure 1. ErbB receptors are expressed during early Xenopus embryogenesis. A: Alignment of the four Xenopus ErbBs in the conserved domain shows that they are homologous to each other, with 65 to 88% identical residues in this region. Shaded residues are identical in all four ErbBs. B: The Xenopus ErbB fragments are highly homologous to their human counterparts in the conserved region in the tyrosine kinase domain, with 94, 93, 82, and 96% similarity between Xenopus EGFR, ErbBs 2, 3, 4, and their corresponding human homologs, respectively. C: RT-PCR analysis shows that all ErbBs are expressed maternally, and the expression persists to at least tailbud stages during early Xenopus development. D: Expression of XErbB2 detected by in situ hybridization. XErbB2 was expressed widely in both ectodermal and mesodermal regions during gastrula and early neurula stages (i-iii). During neurulation (iv) and early tailbud stages (v), its expression was elevated in the neural tissues. Starting from early tailbud stages, its transcripts were also seen in myotomal muscles in addition to neural and neural crest-derived structures, such as brain, spinal cord, eyes, and branchial arches (v-viii). This expression pattern persists to at least tadpole stages (ix). i and ii are animal and vegetal views of mid-gastrula embryos, respectively; iii. iv, and vii are dorsal views of late gastrula, neurula, and tailbud embryos, respectively; v, vi, viii, and ix are lateral views of tailbud and tadpole stage embryos. E: Xenopus EGFR (i-v), ErbB3 (vi-x), and ErbB4 (xi-xv) are expressed widely during early development. At gastrula stages, they were expressed uniformly in ectodermal and mesodermal regions (i, ii, vi, vii, xi, xii), and the expression was increased in the neural tissues during neurulation (iii, viii, and xiii). At tailbud stages, the expression was seen in the brain, spinal cord, brachial arches, somites, eyes, and otic vesicles (iv, v, ix, x, xiv, xv). The embryos were viewed from animal (i, vi, xi) or vegetal (ii, vii, xii) sides at gastrula stages; and from lateral (iii, v, x, xiv, xv) or dorsal (iv, viii, ix, xiii) sides with the anterior to the left for neurula and tailbud embryos. Image published in: Nie S and Chang C (2006) Copyright © 2006. Image reproduced with permission of the Publisher, John Wiley & Sons.
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