(A), The expression of EMX2 gene is specifically disturbed in head of zebrafish after zSmE deficiency. (B), The zSmE deficiency leads to increased intron retention of EMX2. (C), The head defect caused by zSmE deficiency can be partially rescued by transcription factor EMX2. The morpholino and/or in vitro transcribed RNA is injected into embryo at 1-cell stage. Yellow line marked the region for quantification. (D), Quantification of zebrafish head size. Left, head size; middle, body length; right, head size normalized by body length. UN, un-injected; CO-MO, control morpholino; E-MO, SmE morpholino, EMX2, EMX2 gene in vitro transcript. The UN is normalized to 1. * P<0.05; ** P<0.01.