The gap genes play a key role in establishing pair-rule and homeotic stripes of gene expression in the Drosophila embryo. There is mounting evidence that overlapping gradients of gap gene expression are crucial for this process. Here we present evidence that the segmentation gene giant is a bona fide gap gene that is likely to act in concert with hunchback, Kruppel and knirps to initiate stripes of gene expression. We show that Kruppel and giant are expressed in complementary, non-overlapping sets of cells in the early embryo. These complementary patterns depend on mutually repressive interactions between the two genes. Ectopic expression of giant in early embryos results in the selective repression of Kruppel, and advanced-stage embryos show cuticular defects similar to those ohserved in Kruppel- mutants. This result and others suggest that the strongest regulatory interactions occur among those gap genes expressed in nonadjacent domains. We propose that the precisely balanced overlapping gradients of gap gene expression depend on these strong regulatory interactions, coupled with weak interactions between neighboring genes.
|Original language||English (US)|
|Number of pages||11|
|State||Published - Mar 14 1991|
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Developmental Biology
- gap genes