Sex, flies and microarrays

In a typical microarray study, experimental RNA samples are compared to a r eference sample and expression ratios are clustered. A new study of the eff ects of sex, aging and genotype on gene expression in Drosophila melanogast er departs from this paradigm. Highly replicated comparisons generate measu res of expression that are analyzed using classical analysis of variance (A NOVA) techniques, revealing substantial differences in gene expression betw een the two sexes as well as smaller effects of age and strain. Moreover, t his study demonstrates that replication and experimental design are essenti al to detecting small but biologically important differences in expression patterns.