Sex, flies and microarrays

In a typical microarray study, experimental RNA samples are compared to a reference sample and expression ratios are clustered. A new study of the effects of sex, aging and genotype on gene expression in Drosophila melanogaster departs from this paradigm. Highly replicated comparisons generate measures of expression that are analyzed using classical analysis of variance (ANOVA) techniques, revealing substantial differences in gene expression between the two sexes as well as smaller effects of age and strain. Moreover, this study demonstrates that replication and experimental design are essential to detecting small but biologically important differences in expression patterns.