Mxtx2 Is Required for and Sufficient for YSL Induction
(A) Lateral view of embryos injected with 500 pg control morpholino (con-MO), 500 pg mxtx2 morpholino (mxtx2-MO), or 100 pg mxtx2 mRNA at the one-cell stage. At the 80% epiboly stage, mxtx2 morphants develop a yolk burst phenotype, and the mxtx2 mRNA-injected embryo failed to undergo epiboly. The YSL markers gata6, camsap1l1, hnf4a, and slc26a1 were absent in the mxtx2 morphant. YSL genes were ectopically expressed in the embryos injected with mxtx2 mRNA.
(B) Defective Nodal signaling and endoderm formation in the mxtx2 morphant. ndr1 and ndr2 are shown as a lateral view with the presumptive dorsal side to the right. gata5 and sox32 staining is shown as an animal view with the dorsal side to the right.
(C) By overexpressing nanog-like-Myc, expression of mxtx2, gata6, and camsap1l1 in nanog-like morphants can be rescued. CHX was added at 2 hpf to allow for the translation of injected nanog-like-Myc mRNA but to prevent translation of the earliest zygotic transcripts. When CHX is added at 2 hpf, expression of mxtx2, but not gata6 or camsap1l1, can still be rescued, indicating that mxtx2 is the direct target of Nanog-like.
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