Fig. 1

Tbx6 induces mesp-b paralogs and ripply1 before the onset of myogenesis in lateral paraxial mesoderm. (A-E) Labeling for tbx6, mesp-ba, ripply1 and myoD mRNAs, and for Tbx6 and myosin heavy chain (MF20) proteins at the 10-somite stage. Unbroken lines indicate most recently formed somites (SI-SIII); dashed lines indicate future somites (S0, S-I, S-II) in the anterior pre-somitic mesoderm (PSM). Scale bar: 100µm. (F) Anti-Myc immunoprecipitation from Tg(hsp70l:tbx6^myc) embryos 1h after heat shock and subsequent sequencing reveals Tbx6^Myc genomic binding proximal to mesp-ba, mesp-bb and ripply1. Shown are 35-kb windows encompassing significant peaks in reads per million (RPM) (supplementary material Table S1). Black asterisks indicate correspondence with T-box binding sites identified by Cutty et al. (2012). Red asterisks indicate peaks confirmed by ChIP-PCR (supplementary material Fig. S2). (G) Top sequence motif found in Tbx6^Myc binding peaks (supplementary material Table S2). (H) Schematic showing spatial and temporal correlation of tbx6, mesp-ba and ripply1 expression with the onset of dermomyotome and myotome (slow and fast fiber) development (adapted from Stellabotte and Devoto, 2007).