title: An iron-rich organelle in the cuticular plate of avian hair cells.
abstract: Hair cells reside in specialized epithelia in the inner ear of vertebrates, mediating the detection of sound, motion, and gravity. The transduction of these stimuli into a neuronal impulse requires the deflection of stereocilia, which are stabilized by the actin-rich cuticular plate. Recent electrophysiological studies have implicated the vestibular system in pigeon magnetosensation. Here we report the discovery of a single iron-rich organelle that resides in the cuticular plate of cochlear and vestibular hair cells in the pigeon. Transmission electron microscopy, coupled with elemental analysis, has shown that this structure is composed of ferritin-like granules, is approximately 300-600 nm in diameter, is spherical, and in some instances is membrane-bound and/or organized in a paracrystalline array. This organelle is found in hair cells in a wide variety of avian species, but not in rodents or in humans. This structure may function as (1) a store of excess iron, (2) a stabilizer of stereocilia, or (3) a mediator of magnetic detection. Given the specific subcellular location, elemental composition, and evolutionary conservation, we propose that this structure is an integral component of the sensory apparatus in birds.
authors.affiliation: Institute of Molecular Pathology, Dr. Bohr-Gasse 7, 1030 Vienna, Austria.
authors.forename: Mattias
authors.initials: M
authors.lastname: Lauwers
authors.forename: Paul
authors.initials: P
authors.lastname: Pichler
authors.forename: Nathaniel Bernard
authors.initials: NB
authors.lastname: Edelman
authors.forename: Guenter Paul
authors.initials: GP
authors.lastname: Resch
authors.forename: Lyubov
authors.initials: L
authors.lastname: Ushakova
authors.forename: Marion Claudia
authors.initials: MC
authors.lastname: Salzer
authors.forename: Dominik
authors.initials: D
authors.lastname: Heyers
authors.forename: Martin
authors.initials: M
authors.lastname: Saunders
authors.forename: Jeremy
authors.initials: J
authors.lastname: Shaw
authors.forename: David Anthony
authors.initials: DA
authors.lastname: Keays
mesh_terms: D000818:Animals; D010856:Columbidae; D006198:Hair Cells, Auditory / Q000378:metabolism* / Q000648:ultrastructure; D018069:Hair Cells, Vestibular / Q000378:metabolism* / Q000648:ultrastructure; D007501:Iron / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D015388:Organelles / Q000378:metabolism*
chemical_list: D007501:Iron