Hubert Amrein, Molecular Genetics & Microbiology

The main interest of our laboratory is concerned with the molecular mechanism that leads to the two-fold up regulation of all X-linked genes in males (Dosage compensation). Five genes involved in this process have been characterized both at the genetic and molecular level. They are collectively called the "male-specific lethal" (msl) genes, since mutations in each of them cause male-specific lethality. All encode nuclear proteins that associate specifically with the single X chromosome of male cells. It is thought that this association leads to a modification of X chromatin, resulting in increased and more efficient transcription of X-linked genes, but the mechanism of how this is achieved remains unknown. Recently, others and we have shown that the Msl association with the male X chromosome is accompanied with the simultaneous association of two RNAs, roX1 and roX2, both of which are encoded by genes that map on the X-chromosome. We are interested if and how these RNAs mediate the Msl-X-chromosome interaction and we use both genetic and molecular strategies to address this question.

A second interest of the laboratory is concerned with olfactory perception of the fruit fly. Olfaction in Drosophila is mediated through a large family of sixty-seven trans-membrane proteins that are expressed in the antenna (the 'fly nose') and are thought to mediate specific behaviors of the fly in response to different odorants. We are employing a molecular genetic strategy to generate flies that can only express one functional receptor to determine ligand specificity of such receptors. Furthermore, we are interested in systematic changes that take place during development. The larval olfactory system is replaced by the adult olfactory system during metamorphosis. Interestingly, the odorant receptors that are expressed in the adult are not expressed in the larval olfactory system. Thus, another yet unknown class of receptors must mediate larval olfactory behavior and we employ a molecular analysis of candidate genes obtained for the Drosophila Genome Sequence to identify these olfactory receptor genes.