Lack of YSL Transcription in nanog-like Morphants Leads to Epiboly and Endoderm Defects
(A) Microarray analysis of gene expression in nanog-like morphants revealed an absence of YSL gene transcription. YSL genes downregulated in three separate experiments are displayed as a heat map.
(B) The expression of gata6, mxtx2, camsap1l1, hnf4a, and slc26a1 is absent in the YSL of nanog-like morphants. All views are lateral with the presumptive dorsal side to the right.
(C) The YSN of the wild-type and nanog-like knockdown embryos at the sphere stage and the 50% epiboly stage labeled with SYTOX green. All views are shown as an animal view with the dorsal side to the right.
(D) Time-lapse microscopy of the YSNs of a nanog-like-MO2-injected embryo revealed the YSN aggregation process. Three YSNs undergo the 12th division at t = 16 min. At t = 22 min, the upper left YSNs separate normally while the lower YSNs fail to completely separate. At t = 36 min, the resulting six daughter YSNs start to aggregate.
(E) Higher magnitude confocal microscopy revealed that the aggregated YSNs in Figure 3D remained separated.
(F) Nanog-like is required autonomously for YSL transcription. To achieve YSL-specific expression, 300 pg nanog-like-Myc mRNA was injected into the yolk at 2.5 hpf. The expression of mxtx2, gata6, and camsap1l1 was rescued by YSL-specific nanog-like-Myc expression.
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