One of the most powerful tools in Drosophila developmental genetics is the use of transgenic flies to discover new genes, report gene expression and

One of the most powerful tools in Drosophila developmental genetics is the use of transgenic flies to discover new genes, report gene expression and to alter gene expression, function and cell physiology. Experience how one gene discovery technique, the enhancer trap, is used to characterise a gene. An enhancer trap is the insertion of a transposon (the P element) in or near the regulatory region of an endogenous gene, so that a reporter gene (detectable by immunoshistochemistry or fluorescence microscopy) will mimic the spatial and temporal pattern of gene expression through development. An alternative approach is cloning the enhancer and placing it in the transposon with the reporter. This requires the previous molecular identification of the gene of interest, and is the case with the Tailup (tup) reporter.

1. What regulates the spatial pattern of reporter expression? 
2. Can reporter constructs stably inserted in an organism genome be deleterious to this organism? Explain.
3. With information gleamed from FlyBase, Flymove and Interactive Fly web sites summarise the nature of the tup gene product. (What kind of protein and signal transduction pathway?). 
4. Under what circumstances can the pattern of expression of a hypothetical gene detected using immuno-labelling differ from that detected using a reporter construct?