Is an ortholog of human APEX1 (apurinic\/apyrimidinic endodeoxyribonuclease 1). Exhibits DNA-(apurinic or apyrimidinic site) endonuclease activity and phosphoric diester hydrolase activity. Is involved in base-excision repair\; embryo development\; and nematode larval development. Is expressed in the hermaphrodite gonad and the male gonad.