Extended Data Fig. 8: Gene expression data in Australian lungfish, ray-finned fish and axolotl salamader.
From: Giant lungfish genome elucidates the conquest of land by vertebrates
a, Neoceratodus only has a single right lung. shh expression in the Neoceratodus lung anlage. Stage (st.) 43 ventral view (n = 1 out of 1 embryo), anterior up. Stage-48 ventral view, anterior up (n = 1 out of 1 embryo). The appearance of the lung anlage and shh expression is similar to that in Xenopus. Transverse section across dotted line. lu, lung; in, intestine. Scale bars, 0.2 mm. b, LacZ enhancer assays in mouse 12-dpf embryos show the regulatory activity of several ultraconserved enhancers that emerged in association with the evolution of the lobed fin. These include elements located near important limb developmental genes that contribute to the sturdy sarcopterygian fin archetype (Supplementary Results). Reported LacZ limb expression: hs1603, n = 7 out of 7 embryos; hs895, n = 5 out of 8 embryos; hs1442, n = 10 out of 11 embryos; mm117993,94, n = 7 out of 7 embryos; mm1887, n = 6 out of 6 embryos; hs1438, n = 5 out of 11 embryos. c, hox gene expression from RNA-seq analysis of stage-52 pectoral fins (n = 2). Individual data points shown with asterisks; the height of the bar indicates average expression. Overlapping data points indicated with a single asterisk. High expression of posterior hoxa and hoxd genes (except for hoxa14), low expression of hoxb genes and unexpectedly high expression of hoxc genes. d, Absence of hoxc13 expression from pectoral, but not caudal, fins in the ray-finned cichlid Astatotilapia burtoni. A staging series of cichlid pectoral fins (5–7 dpf) does not show expression of hoxc13, whereas this gene stains strongly in the caudal fin (n = 4/4 embryos per stage). This result is consistent with a sarcopterygian origin of hoxc13 expression in the distal paired fins and limbs. Scale bars, 0.1 mm. e, Non canonical patterns of hoxd9 and hoxd10 expression in axolotl limbs (n = 2/2 limbs per stage). Expression of hoxd9 and hoxd10 during axolotl limb development shows strong expression in a proximal limb domain but absence or low expression in the distal limb or digit domain. This noncanonical expression is similar to that previously reported for hoxd1137,95, and suggests a loss of contact with the distal limb enhancers located 5′ of the hoxd cluster, caused by the expansion of the posterior hoxd cluster. Scale bars, 0.2 mm. Silhouettes are from ref. 36.
