title: Absence of the symbiont Candidatus Midichloria mitochondrii in the mitochondria of the tick Ixodes holocyclus.
abstract: Candidatus Midichloria mitochondrii (M. mitochondrii) belongs to a novel clade of bacteria within the order Rickettsiales. Recent PCR-based screening studies indicate that it is present in a number of blood-sucking arthropods, as well as the blood of some vertebrates. Its medical and veterinary significance remains to be determined. Electron microscopic examinations of M. mitochondrii have thus far been conducted on two infected tick species. Remarkably, the bacterium was found in abundance within the mitochondria of the ovarian cells of each tick species. This makes it the only characterized bacterium able to invade the mitochondria of any multicellular organism. To examine whether mitochondrial invasion is a consistent characteristic of M. mitochondrii, we examined two tick species found in Eastern Australia. One of these species, Ixodes holocyclus, was infected with two M. mitochondrii strains; however, no bacteria were seen in the mitochondria. Comparative studies involving these strains may shed light on the unique phenomenon of mitochondrial invasion.
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Sydney, NSW, Australia.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Beninati
authors.forename: Markus
authors.initials: M
authors.lastname: Riegler
authors.forename: Inger-Marie E
authors.initials: IM
authors.lastname: Vilcins
authors.forename: Luciano
authors.initials: L
authors.lastname: Sacchi
authors.forename: Raelene
authors.initials: R
authors.lastname: McFadyen
authors.forename: Mark
authors.initials: M
authors.lastname: Krockenberger
authors.forename: Claudio
authors.initials: C
authors.lastname: Bandi
authors.forename: Scott L
authors.initials: SL
authors.lastname: O'Neill
authors.forename: Nathan
authors.initials: N
authors.lastname: Lo
mesh_terms: D020561:Alphaproteobacteria / Q000302:isolation & purification* / Q000502:physiology*; D000818:Animals; D001315:Australia; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005260:Female; D006801:Humans; D018884:Ixodes / Q000382:microbiology* / Q000502:physiology*; D008297:Male; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000382:microbiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013559:Symbiosis
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S