Skip to main content
Fig. 4 | BMC Biology

Fig. 4

From: Mutation of amphioxus Pdx and Cdx demonstrates conserved roles for ParaHox genes in gut, anus and tail patterning

Fig. 4

Inhibiting RA pathway partially rescues Cdx mutant phenotype. The large tail fin evident in wild type and Cdx+/− heterozygous (‘normal’) amphioxus larvae (a, 30 h) is severely truncated in Cdx−/− homozygous mutants and develops from fewer epidermal cells (b). Inhibition of the RA pathway using BMS493 enlarges the tail fin of normal larvae (c) and partially rescues the truncation in Cdx−/− mutants (d). Tail fin development is presaged by the expression of the Rootletin gene in 18-h late neurula embryos, visualised by in situ hybridisation (e), which is also downregulated in Cdx−/− mutants (f). Inhibition of the RA pathway results in the upregulation of Rootletin RNA to varying degrees in normal (g, i) and mutant (h, j) embryos. In contrast, posterior expression of Cyp26-3 in 16-h embryos (k) is downregulated in Cdx−/− mutants (l) and by inhibition of RA action (m, n). These data are consistent with a model (o) involving inhibition of RA signalling by Cdx and a feedback loop; interactions in dotted lines are either not confirmed (Cdx effect on RA independent of Cyp26-3) or deduced from previous work (RA inhibition of Cdx [14]). Anterior to the left, dorsal to the top in all images. Scale bar in a, 50 μm, refers to a–d; scale bar in e, 50 μm, refers to e–n

Back to article page