title: Ant antennae: are they sites for magnetoreception?
abstract: Migration of the Pachycondyla marginata ant is significantly oriented at 13 degrees with respect to the geomagnetic north-south axis. On the basis of previous magnetic measurements of individual parts of the body (antennae, head, thorax and abdomen), the antennae were suggested to host a magnetoreceptor. In order to identify Fe(3+)/Fe(2+) sites in antennae tissue, we used light microscopy on Prussian/Turnbull's blue-stained tissue. Further analysis using transmission electron microscopy imaging and diffraction, combined with elemental analysis, revealed the presence of ultra-fine-grained crystals (20-100 nm) of magnetite/maghaemite (Fe(3)O(4)/gamma-Fe(2)O(3)), haematite (alpha-Fe(2)O(3)), goethite (alpha-FeOOH) besides (alumo)silicates and Fe/Ti/O compounds in different parts of the antennae, that is, in the joints between the third segment/pedicel, pedicel/scape and scape/head, respectively. The presence of (alumo)silicates and Fe/Ti/O compounds suggests that most, if not all, of the minerals in the tissue are incorporated soil particles rather than biomineralized by the ants. However, as the particles were observed within the tissue, they do not represent contamination. The amount of magnetic material associated with Johnston's organ and other joints appears to be sufficient to produce a magnetic-field-modulated mechanosensory output, which may therefore underlie the magnetic sense of the migratory ant.
authors.affiliation: Fakultät für Chemie-FG Elektronenmikroskopie-Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany. jandiuff@cbpf.br
authors.forename: Jandira Ferreira
authors.initials: JF
authors.lastname: de Oliveira
authors.forename: Eliane
authors.initials: E
authors.lastname: Wajnberg
authors.forename: Darci Motta de Souza
authors.initials: DM
authors.lastname: Esquivel
authors.forename: Sevil
authors.initials: S
authors.lastname: Weinkauf
authors.forename: Michael
authors.initials: M
authors.lastname: Winklhofer
authors.forename: Marianne
authors.initials: M
authors.lastname: Hanzlik
mesh_terms: D000818:Animals; D001000:Ants / Q000737:chemistry* / Q000502:physiology* / Q000528:radiation effects; D004574:Electromagnetic Fields; D007501:Iron / Q000032:analysis*; D008280:Magnetics; D040542:Mechanotransduction, Cellular / Q000502:physiology* / Q000528:radiation effects; D009949:Orientation / Q000502:physiology*; D012679:Sense Organs / Q000737:chemistry* / Q000502:physiology* / Q000528:radiation effects
chemical_list: D007501:Iron