Reduction of Wnt signaling during trunk somitigenesis using hsdkk1 transgene preserves elongation and increases somite length. hsdkk1::GFP heterozygote outcross. (A-D) Posterior elongation and instantaneous somite length over time, showing a representative experiment with heat shock at <9 somites; n=8 per condition. Lateral view of representative heat shocked (hs) wild-type (WT) control (A) or transgenic (B) embryo, with magnification of the last three somites formed (A2,B2) when the tenth somite post-heat shock (phs) forms. (C) Plot of distance between fixed position in somites and posterior tip (white line in A,B) over time. (C2) Elongation rate, 190-430 minutes phs. (D) Box plot of instantaneous somite length (distance between consecutive notches, orange line in A2,B2). (E,F) Dorsal view of flat-mounted anterior PSM of control or transgenic embryo double-stained for mespb (blue) and myoD (red), fixed 4 hours phs. Black arrow indicates the last-formed somite. (G) Segment length (distance between two mespb stripes, white arrow in E,F) in embryos fixed every 30 minutes after heat shock, starting 2.5 hours phs. Mean ± s.d. *P<0.01, **P<0.001; ns, not significant. Scale bars: 50 µm. See also Fig. S1, Table S1, Movies 1-3.
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