FIG. 1.

Constructs used to localize the BIE. The structure of the bicoid gene is drawn from the work of Berleth et al. (6). 5B contains a hybrid between bicoid 5′ sequences and rpA1 gene 3′ sequences. The glue gene sgs3 promoter containing the nurse cell-specific hsp26 enhancer was used to drive the expression of this construct. 3B contains a hybrid between rpA1 gene 5′ sequences and bicoid 3′ sequences. This hybrid gene is under the control of the rpA1 promoter. 5T contains a hybrid between α1-tubulin gene 5′ sequences and bicoid 3′ sequences. The α1-tubulin promoter was used for this construct. In the BBT construct, the bicoid 3′ UTR sequence downstream of the MluI site was replaced by that of the tubulin gene 3′ UTR. The bicoid promoter was used for this construct (a kind gift from P. Macdonald [18]). 3BA, 3BB, 3BC, and 3BD are four overlapping deletion constructs of the 3B construct. The ΔNRE construct contains a bicoid gene with a deletion of 45 nucleotides in the 3′ UTR between the HpaI and EcoRV restriction sites, downstream of the stop codon (a kind gift from R. Wharton [34]). Horizontal lines, nontranscribed flanking regions; ∨s, introns, ░⃞, bicoid protein-coding region; □, bicoid UTRs; ▪, rpA1 protein-coding region; ▩, rpA1 gene UTRs; , tubulin protein-coding region; ▨, tubulin gene UTRs. A DNA cassette encoding the influenza virus HA1 hemagglutinin epitope was inserted (not shown [32]) to maintain the protein reading frame in constructs 5B, 3B, 5T, 3BA, 3BB, 3BC, and 3BD.