Imprecise excision of the progenitor P{PZ}gsb01155 insertion. 2736bp of the 5' end of the original P{PZ} element remain (this includes 2147bp of the Ecol\lacZ coding region), together with 15bp of the 3' end of P{PZ} and 19bp of unknown origin in between. The genomic sequence flanking the site of the insertion are unchanged. The P\T promoter present in the P{PZ-ΔJ46} remnant is expected to generate a Ecol\lacZ-gsb fusion transcript in those cells that would normally express gsb (this is supported by the fact that the truncated Ecol\lacZ present faithfully reproduces the pattern of endogenous gsb in embryos). The insertion is thus expected to interfere with expression of gsb as no internal ribosome entry site is present on the fusion transcript. However, the allele appears to be a very strong, but not a null, gsb allele.
