(a) Overview of functional analysis for 20 muscle-specific genes. Transcript expression patterns are all specific to primary and secondary tail muscle and are strongly expressed by mid-tailbud stage (Supplemental Fig. 1). All initial native-promoter fusion constructs express in the muscle by mid-tailbud, and many demonstrate expression in other tissues (TVC indicates trunk ventral cells; HS, trunk hot spot; NT, notochord; AE, anterior ectoderm; and CNS, central nervous system). The average and median percentage of conservation increases between the initial constructs and the smallest functional constructs. Original indicates the initially tested, long construct with which muscle expression was ascertained; smallest, the shortest construct that gives expression comparable to the original construct. All of the original constructs show expression in the mesenchyme (ME, pink arrows), and some show expression in the CNS (b,c,f). Fragments of the initial constructs of five different loci show notochord expression (NT, green arrow, d,e). Eight constructs express as early as gastrulation (g).
