Andrew Tomlinson, PhD

During the development of multicellular organisms cells differentiate according to the various developmental pathways into which they are directed. Understanding the mechanisms that direct such developmental decisions is key to understanding the phenomenon of development as a whole. The differentiation pathway that a cell adopts can be influenced either by directives it inherits from its progenitors or by the way it assesses environmental signals. These environmental signals are usually molecules secreted from other cells and the research in essence focuses upon the biochemical nature of cell signaling in development and the control of cell fate. We use the fruit fly Drosophila melanogaster as a model system with which to analyze developmental decisions. Using the genetic wealth of this organism we are able to identify key genes involved in the choice of developmental pathways. We predict the phenotypes of mutations in genes involved in the developmental decisions and then screen for them. Having a mutation in a gene then allows us to isolate it and sequence it to establish the type of protein encoded. The genes can then be reintroduced into the organism and expressed inappropriately to assay the effects of ectopic expression. Since we are largely looking at cell signaling mechanisms, we systematically build a molecular picture of how one cell is able to influence the developmental fate of another. Put another way, we are looking at the biochemistry of signal release, signal reception and interpretation, and subsequent cell differentiation.