Centrioles are highly conserved eukaryotic organelles that have evolved multiple cellular functions in higher organisms. Two reports in this issue now investigate the evolution of centrioles through bioinformatic and experimental approaches. Keith Gull and colleagues (p. ) evaluate the distribution of 53 proteins from 45 eukaryotic species to define which centriolar proteins were present in the common eukaryotic ancestor. Among many interesting conclusions, their analyses reveal that ancestral centriolar proteins include a set of 14 core components. In addition, analysis of proteins associated with ciliopathies (which present with the eye disease retinitis pigmentosa) also sheds light on eye evolution. Mónica Bettencourt-Dias and colleagues (p. ) use comparative genomics to investigate the evolution of centriole-assembly mechanisms. They search 26 eukaryotic species for orthologues of six human proteins known to be involved in centriole assembly, and experimentally test their predictions. Together, these two reports indicate a stepwise evolution of centriole structure and function: the core assembly machinery that enables centrioles to nucleate cilia and flagella is ancestral, whereas centrosomes evolved more recently (as centrosomal components are found mainly in Holozoa). Overall, these analyses provide insight into how the evolution of centriolar components has enabled adaptation of this structure to new cellular functions.
