Xenbase Image ID: 138112

Figure 1. Tra2b Is Required for Somite Formation and Normal Embryogenesis (A) A translation-blocking MO was used in X. laevis, and a splice-blocking MO was used in X. tropicalis. (B and C) Delayed gastrulation in tra2b morphants at stage 14; red arrow indicates protruding mesendoderm in morphants (103/110 embryos). (D and E) Neural tube closure defects at stage 18. White arrows indicate fused neural folds in control embryos; red arrows point to neural folds in the open neural plate of morphants (98/101 embryos). (F–H) Axis elongation defects and endoderm detachment at stage 23. Red arrows in (G) and (H) indicate endoderm detaching from the embryo through the blastopore (87/99 embryos). (B–E) Dorsal view with anterior up. (F and G) Lateral view with anterior to the left. (H) Posterior view with dorsal up. (I–R) In situ hybridization (ISH) on control and tra2b morphants. (I–L) Neural plate morphology (sox2) and mesoderm specification (t/bra) at stage 15. (M and N) Paraxial mesoderm forms in tra2b morphants, but does not segregate into segmented muscle blocks. White arrow in (M) indicates segregated muscle block in control embryo. (O and P) Presomitic mesoderm (PSM) is present in tra2b morphants (white brackets), but presomitic stripe formation is compromised. White arrow in (O) indicates normal stripe pattern, red arrow in (P) points to smaller and fewer stripes in tra2b morphants. (Q and R) Mature somites marked by hey1 are almost completely absent in tra2b morphants. (S and T) Quantification of hey1-positive somites and pcdh8-positive stripes in control and tra2b morphants. Bars show mean + SD; ∗∗∗ indicates that the difference compared with control is significant at p < 2.2 × 10−16 (t test). Number of embryos used for quantification: 63 (ctrl, hey1), 58 (tra2bMO, hey1), 68 (ctrl, pcdh8), and 59 (tra2bMO, pcdh8). Embryos shown are X. laevis. See also Figure S1. Image published in: Dichmann DS et al. (2015) Copyright © 2015. Image reproduced with permission of the publisher and the copyright holder. This is an Open Access article distributed under the terms of the Creative Commons Attribution License. Gene Synonyms Species Stage(s) Tissue sox2.L anop3, LOC108718087, mcops3, Sox-2, XLSOX-2, Xsox-2, XSox2 X. laevis Throughout NF stage 15 neural plate pre-chordal neural plate chordal neural plate tbxt.S bra, brachyury, ntl, t, t-a, t-b, X-bra, Xbra, Xbrachyury X. laevis Throughout NF stage 15 circumblastoporal collar involuted dorsal mesoderm involuted ventral mesoderm myod1.S mf25, MyoD, myod1-a, myod1-b, myogenic factor 3, XMyoD, XtmyoD X. laevis Throughout NF stage 18 presomitic mesoderm somite pcdh8.L papc, paraxial protocadherin, xpapc X. laevis Throughout NF stage 18 presomitic mesoderm somite hey1.S bc8, chf2, herp2, hesr1, hrt-1, hrt1, oaf1, XHRT1 X. laevis Throughout NF stage 18 somite presomitic mesoderm Image source: Published Larger Image Printer Friendly View

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