Figure 4 .

ELAV-dependent regulation of ewg intron 6 is promoter-independent. (A–C) Expression of endoA, nwk, and Nrx-1 genes in embryos is confined to the ventral nerve cord as shown by RNA in situ. (Right) The promoter fragment used to drive expression of the tcgR construct is shown as a bold line at the bottom of the genomic organization. (D) Schematic of the tcgRm reporter construct with primers used in E depicted at the top. (E) Semiquantitative RT-PCR of intron 6 splicing using ³²P-labeled forward primers from tcgERm compared to tcgRm-endoA, tcgRm-nwk, and tcgRm-NRX-1 transgenes in ewg^∆, an RNA null allele using primers 6F and VSV-R (cycle 26). Expression levels of transgenes was determined with primers 4F and 5R (cycle 24) and expression levels of elav from primers elavFhinge/elavBamR (cycle 28) are shown as standard. The linear amplification range is indicated on the right for the control (lanes 5–7). PCR products were analyzed on 8% polyacrylamide gels. Quantification of three experiments is shown at the bottom.