Xenbase Image ID: 144601

Figure 4. Association of XHex expression with development of anterior head structures and persistent expression in UV-ventralised embryos. (a–c) Induction of ectopic XHex expression by ventrovegetal injection of β-catenin RNA. (a) Injected embryos formed complete secondary axes, which included the most anterior structures. (b) Ectopic XHex expression was always detected in such embryos. (c) Higher-magnification view of one such embryo. Ectopic XHex transcripts as well as endogenous expression of the gene were detected in deeply located endodermal cells. Note the absence of detectable expression in cells located superficially to the XHex-expression domain. (d–f) Induction of partial secondary axes by lateroventral expression of a truncated BMP receptor. (d) The induced partial secondary axes lacked anterior structures, and (e) no ectopic XHex expression was detected. (f) Lineage tracing of cells expressing the truncated BMP receptor (red) confirmed that no XHex expression was detected in the injected cells. In this specimen, XHex transcripts are evident immediately adjacent to the dorsal blastopore lip and as faintly staining cells deeper within the embryo. Embryos in (b,c,e) were cleared, but the embryo in (f) was not. (g) RT–PCR showing persistence of XHex and cerberus transcript levels when dorsoaxial development was compromised following UV irradiation. The average dorsoanterior index of treated embryos was 0, and the effective treatment is confirmed by the abolition of goosecoid expression. The last lane shows a control PCR in which the reverse transcription step was omitted (−RT). The RT–PCR to detect expression of elongation factor 1α (EF1α) served as a loading control. Image published in: Jones CM et al. (1999) Copyright © 1999. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View

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