Research Highlight Sensorium: The Original Raison D’être of the Motile Cilium?

The role of non-motile (primary) cilia as sensory antennae critical for metazoan development and physiology has surfaced over the last decade, long after the function of motile cilia in propelling cells or moving fluids across tissues was well established. A new study of motile cilia from respiratory airways raises the possibility that transducing sensory cues from the environment is a universal characteristic of cilia and may have been the original raison d’être of the ancestral cilium. Cilia are tail-like cellular projections found on the surfaces of most eukaryotic cells (Pedersen and Rosenbaum, 2008). The quintessential motile cilia, also termed fla-gella, are used to propel cells through an aqueous medium or move fluid over cell surfaces. For example, they provide moti-lity to gametes and protists such as Chlamydomonas or Paramecium, which are engaged in moving through their environment in response to variou