Mis-regulating segmentation gene expression in Drosophila. Development 111:1121–1135

We have used the hunchback (hb) gap-gene promoter to drive ectopic expression of the pair-rule genes fushi tarazu (ftz), even-skipped (eve) and hairy (h). Unexpec-tedly, flies transformed with such constructs are viable, despite spatial and temporal mis-regulation of pair-rule expression caused by the fusion genes. We show that fusion gene expression is transcriptionally regulated, such that ectopic expression is suppressed when pattern is established, and present evidence indicating that interstripe hb-ftz expression is repressed by eve. These results are considered in terms of redundant control of pair-rule gene striping. We also discuss the potential dangers of using mis-regulated gene expression to analyse normal function. Key words: segmentation gene expression, embryonic pattern formation, pair-rule genes, genetic redundancy, hunchback, mis-regulation, Drosophila