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The influence on the blastoderm fate map of maternal-effect genes that affect the antero-posterior pattern in Drosophila

1987; Cold Spring Harbor Laboratory Press; Volume: 1; Issue: 6 Linguagem: Inglês

10.1101/gad.1.6.603

1549-5477

Marek Mlodzik, Catherine Millard De Montrion, Yasushi Hiromi, Henry M. Krause, Walter J. Gehring,

Genomics and Chromatin Dynamics

The polarity and the spatial coordinates of the egg and the developing embryo are largely specified by maternal-effect genes.Mutations in several of these genes cause deletions of head structures and, in some cases, their replacement by posterior structures.Here, we analyze embryos derived from females with mutations in the loci exuperantia (exu), torso (tor), trunk (trk), and bicoid (bcd).The effects of these mutations can be monitored at the blastoderm stage, when the outlines of the body plan are laid down, by the visualization of RNA or protein products of genes that are expressed in a spatially restricted pattern.We have used antisera and/or cloned DNA probes to detect the localization of the gene products of the segmentation genes fush/ tarazu (ftz) and hairy (!1).In exu-embryos, Deformed (Dfd) and caudal (cad) probes were also used as markers of the anterior and posterior ends, respectively.We find that exu, a mutation leading to head defects, has a pronounced long-range effect on the fate map, enlarging the region of the thoracic anlagen in the anterior direction and compressing the abdominal anlagen.In contrast, tot and trk do not change the fate map over the entire embryo but have more localized effects.In embryos derived from bcd mothers, head and thoracic structures are missing and replaced by a duplicated telson, the most posterior structure.These changes can be detected in the blastoderm as an anterior shift of the posterior anlagen and the formation of a posterior ftz stripe at the anterior end.