Fig. 1. Ice¹ is a null allele of Ice. (A) Genomic organization of the Ice region. The P transposon element EP^GE28489 is inserted at base 1711 in the Ice transcription unit. The Ice¹ excision line removes the entire Ice-coding region, fusing small remaining fragments of the Ice 5'- and 3'-UTR sequences. A 1.5 kb fragment of EP^GE28489 also remains. The gray region indicates the Ice-coding region; the black boxes indicate the UTR sequences of Ice and of two neighboring genes. Locations of the EP^GE28489 element, the Ice¹ deletion and the Ice genomic rescue construct (Ice^+2.4) are indicated to scale. (B) Western blot of adults of various genotypes probed with anti-Ice antibodies. The genotypes are wild type, Ice¹, Ice¹; Ice+2.4 and dcp-1^Prev1 (Dcp-1), a null allele of dcp-1.