The Ultrabithorax (Ubx) gene is of great importance for the evolution of athropods. This gene belongs to the class
of "homeotic" genes that determine the identity of different body parts. These genes are conserved throughout
animal kingdom. Ubx is a transcription factor which regulates the expression of many other genes. It is not known
how many genes and in which way these genes are controlled by Ubx. These downstream genes of Ubx and other
"master genes" are probably important points of evolution between two species. In this project the evolution of
genes between two species that are controlled by Ubx will be studied. This goal has become possible to address
because of the availability of the whole genome sequence of two related fruitfly species: Drosophila melanogaster
and Drosophila pseudoobscura. Questions that will be addressed in this study are: How many genes are
differentially regulated? Which class of genes are differentially regulated? Which genes are direct targets of Ubx
and which are regulated indirectly via mediating gene products? Has Ubx or the target genes themselves changed
or was evolution due to the change of regulatory sequences which are located around target genes? To determine
gene expression of target genes of Ubx "microarrays" will be used. In both species differences in gene expression
between "normal" fly-embryos (wildtype) and mutants (where Ubx is non-functional) will be determined. Direct
targets of Ubx will be determined using a novel method that allows to map protein-DNA interactions throughout
the whole genome. Regulatory sequences around target genes will be determined using computational and
experimental methods and their impact will be tested.