Construct: The nos promoter drives expression of bcd cDNA in which the 5' UTR and part of the 3'UTR have been replaced by 5' and 3'UTR sequences from nos. (Construction notes - 1. The 5'UTR also contains some sequence from the Xenopus leavis Β-globin 5'UTR originating in bcdTN3; 2. The bcd 3'UTR sequence present is truncated at an HpaI site 5' to the nos response element; 3. The nos 3'UTR fused to this HpaI site is an EcoRI-NotI fragment from nosgnosb and includes some nos 3' genomic sequence).
bcdnos.β.nos3'UTR embryos show no evidence of posterior segmentation defects. Germ cell migration in these embryos is indistinguishable from wild-type until stage 10. Although the germ cells appear to segregate into two clusters on either side of the ventral midline, they either fail to associate with the somatic gonadal mesoderm or sustain contact with the somatic gonad. At stage 13, many of the germ cells in these embryos are scattered through several segments rather than having coalesced in the somatic gonad.
