doi:10.1016/j.bpj.2010.05.034engFaivre, DamienFischer, AnnaGarcia Rubio, InesMastrogiacomo, GiovanniGehring, AndreasDevelopment of cellular magnetic dipoles in magnetotactic bacteriaART-2010-90550Magnetotactic bacteria benefit from their ability to form cellular magnetic dipoles by assembling stable single-domain ferromagnetic particles in chains as a means to navigate along Earth's magnetic field lines on their way to favorable habitats. We studied the assembly of nanosized membrane-encapsulated magnetite particles (magnetosomes) by ferromagnetic resonance spectroscopy using Magnetospirillum gryphiswaldense cultured in a time-resolved experimental setting. The spectroscopic data show that 1), magnetic particle growth is not synchronized; 2), the increase in particle numbers is insufficient to build up cellular magnetic dipoles; and 3), dipoles of assembled magnetosome blocks occur when the first magnetite particles reach a stable single-domain state. These stable single-domain particles can act as magnetic docks to stabilize the remaining and/or newly nucleated superparamagnetic particles in their adjacencies. We postulate that docking is a key mechanism for building the functional cellular magnetic dipole, which in turn is required for magnetotaxis in bacteria.2010http://zaguan.unizar.es/record/13166310.1016/j.bpj.2010.05.034http://zaguan.unizar.es/record/131663oai:zaguan.unizar.es:131663BIOPHYSICAL JOURNAL 99, 4 (2010), 1268-1273All rights reservedhttp://www.europeana.eu/rights/rr-f/info:eu-repo/semantics/openAccess