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Fig. 5. myf5 expression is affected by the gain or loss of lbx1. (A,B) A transverse section through an lbx1-splice-injected tadpole (left side uninjected, right injected) reveals not only a loss of ventral body wall muscles (B, arrow), but also a loss of a more dorsal domain of epaxial muscle (B, arrowhead). A corresponding loss of myf5 expression is seen in stage 28 lbx1-splice injected tadpoles. (C,D) An lbx1-splice injected tadpole where C is the uninjected side and D is the injected side. (E,F) Control MO-injected tadpole where E is the uninjected side and F is the injected side. All of these panels are stained for myf5 expression. A loss of myf5 expression in the region that lbx1 is normally expressed is seen in the lbx1-splice-injected tadpole on the injected side (D, arrow). The similar expression domains for lbx1 and myf5 in the hypaxial myoblasts can be seen in G-J. (G,H) A transverse section of a stage 28 tadpole at approximately the level of trunk somite 3. The section is stained for lbx1 (G) and merged with 12/101 staining (H, green). (I,J) Similarly, a transverse section from a stage 28 tadpole at approximately the level of trunk somite 3. This section is stained for myf5 (I) and merged with 12/101 staining (J, green). Both transcripts are found in the ventral hypaxial myoblast region of the somite (H,J, arrows). Overexpression of zebrafish lbx1 causes an increase in myf5 expression and larger somites, but a decrease in differentiated muscle. (K,L) A transverse section of a stage 28 tadpole, showing myf5 staining (K) merged with 12/101 staining (L, green). Embryos were injected into one cell at the two-cell stage. The injected side is to the right. (M,N) Stage 29 tadpole co-injected with lbx1-splice MO and lbx1 mRNA. The uninjected side is shown in M and injected side in N. The loss of myf5 expression is rescued when lbx1 mRNA is added back to lbx1-splice injected cells. |
