Fig. 3. Molecular organization and developmental expression of the tna locus. (A) The tna genomic region is represented at the bottom of the panel. The tna^- P-element insertion sites are indicated by gray circles. The arrows by the insertions represent the orientation of the respective P-element with respect to the tna transcription direction. The tna⁺ EP0374 insertion site is shown as a white circle. The restriction sites are: B, BamHI; X, XbaI; E, EcoRI; H, HindIII. CG6418 is an RNA helicase transcribed towards the 3' end of the tna locus. The transcripts (mRNAs) are depicted in the middle of the panel. The BDGP, release 2-predicted transcripts containing the translated exons (black rectangles for shared, grey rectangles for the non-shared exons between tnaA and tnaB) are shown. We have added the 5' untranslated exon and the 3' poly(A)⁺ regions (white rectangles) deduced from our analysis of the locus. The 5' UTR exon is open on the left to indicate that the tna transcription initiation start site has not been determined. The indicated sizes of both transcripts are in agreement with the northern analysis shown in B. The upper part A (cDNAs) shows representative cDNAs isolated from the tna locus. AT07790 is one of several ESTs identified in adult testis. RE42750 is an EST from adult heads. The ZAP1 embryo cDNA clone was isolated from the UNI-ZAP library from 0-12-hour embryos (see Material and Methods) and was the probe for the northern blot shown in B. The PCR1 embryo cDNA clone was RT-PCR amplified with 5' and 3' primers sequences from the reported LD16921 embryonic clone (see Material and Methods). (B) RNA poly(A)⁺ was prepared from 0-3-hour and 3-21-hour embryos (0-3 and 3-21), first, second and third instar larvae (L1, L2, L3), pupae (P) and adults (A). Samples were blotted and run under standard conditions. The blot was probed with the ZAP1 cDNA (A). The blot was washed and rehybridized using a probe for rp49 as a loading control. The sizes of the detected bands are indicated.