Fig 1

Fig 1 Expression of yap1 and wwtr1 mRNAs during early development.
(A,A’) Schematic indicating the location of antisense probe on each mRNA transcript. In situ mRNA hybridisation for yap1 mRNA (B-K) or wwtr1 mRNA (B’-K’) shown in lateral whole mount, anterior to top (B,B’-D,D’, F,F’, J,J’, K,K’), dorsal flat mount, anterior to top (E,E’, G,G’, H,H’) or transverse cryo-section (B,B’-D,D’, J, J’, K, K’). Maternal yap1 mRNA augmented by zygotic expression at high stage, contrasted with uniform wwtr1 mRNA zygotic expression (C,C’). (E) At 6ss,yap1 mRNA is widespread in forebrain (bracket), notochord (white arrowhead) and lateral somite stripes (black arrowheads), but less apparent in adaxial slow muscle precursors (black arrows). (E’)Wwtr1 mRNA appears more restricted to mid/hindbrain (bracket) and adaxial cells (black arrows), but is absent from notochord (white arrowhead). (F,G) At 10-12ss, notochord (white arrowhead), forebrain (bracket), tail bud (white asterisk) and lateral stripes in nascent somites (black arrowheads) contain yap1 mRNA, but expression appears diminished in more mature somites. (F’,G’) Accumulation of wwtr1 mRNA is observed in adaxial cells (black arrows), stripes in lateral somites (black arrowheads) and mid/hindbrain (bracket), but not in notochord (white arrowhead) or tail bud (white asterisk). (H) At 15ss, myod1 mRNA with yap1 mRNA localises in the anterior half of the somites, alternating with myod1 mRNA (black arrowheads) and notochord (white arrowhead). (H’) Conversely, wwtr1 mRNA co-localises with the myod1 mRNA in the posterior half of each somite (black arrowheads) and adaxial cells (black arrow). (I) Schematic indicating location of flat-mount (I) and 20 μm transverse cryosections (II and III) in J and J’. I’. Schematic indicating location of 15 μm transverse cryosections showing wwtr1 and myod1 mRNA in somitic regions at 32 hpf. (J, J’) At 24 hpf, low level yap1 mRNA was present in dorsal tip (yellow arrowhead) of somite (outlined in yellow dots), whereas wwtr1 mRNA was detected throughout the somitic myotome (yellow asterisks). Both yap1 and wwtr1 mRNAs were present in the eye (white asterisks) and head (brackets). Yap1 mRNA persisted in the tail bud (black asterisk). (K, K’) At 50 hpf, yap1 mRNA persisted at dorsal and ventral somite extremes and was present in heart (inset, black arrowhead) and pectoral fin (red arrowheads) whether viewed from anterior or in 20 μm transverse cryosection (red arrow). Yap1 and wwtr1 mRNAs persisted in the head (white asterisks), but both were reduced in the myotome (yellow asterisks). In pectoral fin, wwtr1 mRNA was detected in two regions consistent with the differentiating muscle masses (red arrows and arrowheads). Bars = 100 μm, except K and K’ 50 μm.