Fig. S19

Trunk myotomes, neurites, notochord and pronephric ducts in embryos treated with SB225002 and XRP44X

Confocal images of DMSO control and small molecule treated embryos at 36 hpf. F-actin visualized with phalloidin (green), acetylated tubulin by immunostaining (magenta) and nuclei with DAPI (cyan). Scale bar is 50 μm. (a-c) Trunk section through myotomes 12 to 17. Myotomes show F-actin organized in skeletal muscle fibres of the DMSO control (d). Muscle fibres are straight and span each myotome from the anterior to the posterior vertical border, highlighted as white lines. (e) In 3 μM SB225002 treated embryos, some vertical myotome borders are discontinuous and less straight (white lines). Occasional appearance of round muscle cells and disorganized structures (arrowheads) in myotomes. (f) Thicker and shorter muscle fibres in 2 μM XRP44X treated embryos. Muscle fibre structure is disorganized; vertical myotome boundary pattern is disrupted (white lines). (g-i) Neurons of the peripheral nervous system (asterisks) and pronephric ducts (arrows) developed and extended along the axis in control and small molecule treatments. Ventral axons of primary motor neurons are bent and shorter in XRP44X treated embryos (i, arrowheads) compared to DMSO control. (j-l) Nuclei show a high density at the level of the spinal cord throughout all tested conditions. (m-o) Cells of the notochord all have vacuoles and are densely packed in control and drug-treated embryos (asterisks). (q-s) Normal extension of the pronephric ducts until the posterior end of the yolk extension towards the developing anus (arrowheads).