title: 'Candidatus Midichloria mitochondrii', an endosymbiont of the tick Ixodes ricinus with a unique intramitochondrial lifestyle.
abstract: An intracellular bacterium with the unique ability to enter mitochondria exists in the European vector of Lyme disease, the hard tick Ixodes ricinus. Previous phylogenetic analyses based on 16S rRNA gene sequences suggested that the bacterium formed a divergent lineage within the Rickettsiales (Alphaproteobacteria). Here, we present additional phylogenetic evidence, based on the gyrB gene sequence, that confirms the phylogenetic position of the bacterium. Based on these data, as well as electron microscopy (EM), in situ hybridization and other observations, we propose the name 'Candidatus Midichloria mitochondrii' for this bacterium. The symbiont appears to be ubiquitous in females of I. ricinus across the tick's distribution, while lower prevalence is observed in males (44%). Based on EM and in situ hybridization studies, the presence of 'Candidatus M. mitochondrii' in females appears to be restricted to ovarian cells. The bacterium was found to be localized both in the cytoplasm and in the intermembrane space of the mitochondria of ovarian cells. 'Candidatus M. mitochondrii' is the first bacterium to be identified that resides within animal mitochondria.
authors.affiliation: Dipartimento di Patologia Animale, Igiene e Sanità Pubblica Veterinaria, Università degli studi di Milano, 20133 Milan, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Sassera
authors.affiliation: School of Biological Sciences, The University of Sydney, New South Wales 2006, Australia.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Beninati
authors.affiliation: Dipartimento di Patologia Animale, Igiene e Sanità Pubblica Veterinaria, Università degli studi di Milano, 20133 Milan, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Bandi
authors.affiliation: Biology Centre, Institute of Parasitology, Academy of Sciences of the Czech Republic, Branišovská 31, 370 05 České Budějovice, Czech Republic.
authors.forename: Edwin A P
authors.initials: EAP
authors.lastname: Bouman
authors.affiliation: Dipartimento di Biologia Animale, Università di Pavia, Piazza Botta 9, 27100 Pavia, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Sacchi
authors.affiliation: Sezione Diagnostica di Pavia, Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna "Bruno Ubertini", 27100 Pavia, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Fabbi
authors.affiliation: School of Biological Sciences, The University of Sydney, New South Wales 2006, Australia.
authors.forename: Nathan
authors.initials: N
authors.lastname: Lo
mesh_terms: D020561:Alphaproteobacteria / Q000145:classification* / Q000302:isolation & purification* / Q000502:physiology / Q000648:ultrastructure; D000818:Animals; D003593:Cytoplasm / Q000382:microbiology; D027081:DNA Gyrase / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005260:Female; D017403:In Situ Hybridization; D018884:Ixodes / Q000382:microbiology* / Q000648:ultrastructure; D008297:Male; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000382:microbiology*; D051336:Mitochondrial Membranes / Q000382:microbiology; D008969:Molecular Sequence Data; D010053:Ovary / Q000166:cytology / Q000382:microbiology; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D013559:Symbiosis
chemical_list: D004269:DNA, Bacterial; D027081:DNA Gyrase