title: Ultrastructure of ellipsoidal magnetotactic multicellular prokaryotes depicts their complex assemblage and cellular polarity in the context of magnetotaxis.
abstract: Magnetotactic multicellular prokaryotes (MMPs) consist of unique microorganisms formed by genetically identical Gram-negative bacterial that live as a single individual capable of producing magnetic nano-particles called magnetosomes. Two distinct morphotypes of MMPs are known: spherical MMPs (sMMPs) and ellipsoidal MMPs (eMMPs). sMMPs have been extensively characterized, but less information exists for eMMPs. Here, we report the ultrastructure and organization as well as gene clusters responsible for magnetosome and flagella biosynthesis in the magnetite magnetosome producer eMMP Candidatus Magnetananas rongchenensis. Transmission electron microscopy and focused ion beam scanning electron microscopy (FIB-SEM) 3D reconstruction reveal that cells with a conspicuous core-periphery polarity were organized around a central space. Magnetosomes were organized in multiple chains aligned along the periphery of each cell. In the partially sequenced genome, magnetite-related mamAB gene and mad gene clusters were identified. Two cell morphologies were detected: irregular elliptical conical 'frustum-like' (IECF) cells and H-shaped cells. IECF cells merge to form H-shaped cells indicating a more complex structure and possibly a distinct evolutionary position of eMMPs when compared with sMMPs considering multicellularity.
authors.affiliation: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil.
authors.forename: Pedro
authors.initials: P
authors.lastname: Leão
authors.affiliation: Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.|CNRS, Laboratoire International Associé de la Bio-Minéralisation et Nano-Structures (LIA-BioMNSL), Marseille, France.
authors.forename: Yi-Ran
authors.initials: YR
authors.lastname: Chen
authors.affiliation: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Abreu
authors.affiliation: Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
authors.forename: Mingling
authors.initials: M
authors.lastname: Wang
authors.affiliation: CNRS, Laboratoire International Associé de la Bio-Minéralisation et Nano-Structures (LIA-BioMNSL), Marseille, France.|Laboratory of Deep Sea Microbial Cell Biology, Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences, Sanya, 572000, China.
authors.forename: Wei-Jia
authors.initials: WJ
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
authors.forename: Ke
authors.initials: K
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.|CNRS, Laboratoire International Associé de la Bio-Minéralisation et Nano-Structures (LIA-BioMNSL), Marseille, France.
authors.forename: Tian
authors.initials: T
authors.lastname: Xiao
authors.affiliation: CNRS, Laboratoire International Associé de la Bio-Minéralisation et Nano-Structures (LIA-BioMNSL), Marseille, France.|Aix Marseille Univ, CNRS, LCB, Marseille, France.
authors.forename: Long-Fei
authors.initials: LF
authors.lastname: Wu
authors.affiliation: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 21941-902, Brazil.
authors.forename: Ulysses
authors.initials: U
authors.lastname: Lins
mesh_terms: D001483:Base Sequence; D020564:Deltaproteobacteria / Q000235:genetics* / Q000648:ultrastructure*; D052203:Ferrosoferric Oxide; D005407:Flagella / Q000235:genetics* / Q000648:ultrastructure*; D008280:Magnetics; D055944:Magnetosomes / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D005810:Multigene Family
chemical_list: D052203:Ferrosoferric Oxide