4Haffter P,Granato M,Brand M,Mullins M C,Hammerschmidt M,Kane D A,Odenthal J,van Eeden F J,Jiang Y J,Heisenberg C P,Kelsh R N,Furutani-Seiki M,Vogelsang E,Beuchle D,Schach U,Fabian C,Nusslein-Volhard C.The identification of genes with unique and essential