Drosophila melanogaster has been the model system of choice for many inv- tigators over the past hundred years. Due to its long-standing tradition as a model organism, many techniques used in Drosophila have been established and c- tinue to be developed to answer a variety of scientific questions. The recent inv- tion of techniques allowing the knock-down of genes by RNA interference and gene replacement by homologous recombination are two important demonst- tions of the ongoing efforts to broaden the technical repertoire at hand for researchers working with Drosophila. This volume is a collection of protocols covering both standard techniques as well as novel methods. An introductory chapter highlights the importance of Drosophila as a model system for the dev- opment of Biology in the 20th century and review chapters provide concise and up-to-date overviews on selected experimental systems. This book makes no attempt to be comprehensive. A number of frequently used standard techniques were selected and are described in-depth to allow novices to get started with Drosophila. In addition, detailed protocols of recently developed methods that we felt will become of broad use in the Drosophila community within the next years are included. I am grateful to Konrad Basler, Suzanne Eaton, Elisabeth Knust, Pavel Tomancak, and Andreas Wodarz for alerting me to novel techniques and for their advice on selecting the protocols for this book. I would also like to thank all the authors for their expert contribution to this Volume. Christian Dahmann v Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .