Read: Martin, SG, Leclerc, V, Smith-Litiere, K, Johnston, DS (2003) The identification of novel genes required for Drosophila anteroposterior axis formation in a germline clone screen using GFP-Staufen. Development 130:4201-4215

In addition, read pp 379-380 of the following review article:

Riechmann, V., and Ephrussi, A. (2001). Axis formation during Drosophila oogenesis. Current Opinion in Genetics & Development 11, 374-383.

Pay particular attention to the dates of references that first report the identification and functional analysis of the genes that are required for establishment of the A-P axis.

1. Many of the genes involved in A-P axis formation in flies were identified in a single mutant screen conducted in the 1970s (Nusslein-Volhard, C. and Wieschaus, E. (1980) Mutations affecting segment number and polarity in Drosophila. Nature 287:795-801). All the genes in Table 9.1 in the text are from this screen, or earlier. Since that time, how many genes with major roles in A-P axis formation have been identified? (We don’t need an exact number, just an approximation by what you can garner from the review article.)

2. What aspects of this experimental design allowed the authors to be so successful in identifying new mutants involved in A-P axis specification?

3. Did you find the number of new mutants these authors were able to identify surprising? Why or why not?

4. Were any new biological insights gained from this genetic analysis? Explain.