Fig. 2. Identification of proteins that control nos-2 translation. (A,B) OMA-1, OMA-2, MEX-3 and SPN-4 are essential for the translation suppression of nos-2 mRNA. Distribution pattern of GFP:H2B expressed under the control of nos-2 3'UTR in oocytes (A; a single oocyte in each panel is outlined) and embryos (B) is shown. Genes disrupted by RNAi treatment are indicated in each panel; WT, non-RNAi control. To facilitate visualization, we expressed GFP as a fusion protein with the histone H2B, which concentrates fluorescence signal in nuclei. (C) POS-1 acts as a de-repressor of nos-2 translation. Epistasis analysis of GFP:H2B expression among mex-3(-), spn-4(-) and pos-1(-) shown here reveals that POS-1 is not required for nos-2 translation in the absence of repressors such as MEX-3 and SPN-4.