Midichlorians, midichloria, and mitochondria

Nathan Lo is an evolutionary biologist interested in creepy crawlies, i.e. arthropods. Well, he’s Australian, so I guess that comes with the territory (see what I did there?). While postdoc’ing, he and his colleagues published a paper (Sassera et al., 2006) that would seem boring for anybody without an interest in taxonomy, a truly under-appreciated field.

The paper describes a bacterium that is a parasite for the mitochondria of a tick species called Ixodes ricinus, the nasty bugger responsible for Lyme disease. The authors obtained a female tick from Berlin, Germany and let it feed on a hamster until it laid eggs. By using genetic sequencing (you can use kits these days to extract the DNA, do PCR, gels and cloning, pretty much everything), electron microscopy (real powerful microscopes) and phylogenetic analysis (using computer softwares to see how closely related some species are) the authors came to the conclusion that this parasite they were working on is a new species. So they named it. And below is the full account of the naming, from the horse’s mouth, as it were:

“In accordance with the guidelines of the International Committee of Systematic Bacteriology, unculturable bacteria should be classified as Candidatus (Murray & Stackebrandt, 1995). Thus we propose the name ‘Candidatus Midichloria mitochondrii’ for the novel bacterium. The genus name Midichloria (mi.di.chlo′ria. N.L. fem. n.) is derived from the midichlorians, organisms within the fictional Star Wars universe. Midichlorians are microscopic symbionts that reside within the cells of living things and ‘‘communicate with the Force’’. Star Wars creator George Lucas stated that the idea of the midichlorians is based on endosymbiotic theory. The word ‘midichlorian’ appears to be a blend of the words mitochondrion and chloroplast. The specific epithet, mitochondrii (mi.to′chon.drii. N.L. n. mitochondrium -i a mitochondrion; N.L. gen. n. mitochondrii of a mitochondrion), refers to the unique intramitochondrial lifestyle of this bacterium. ‘Candidatus M. mitochondrii’ belongs to the phylum Proteobacteria, to the class Alphaproteobacteria and to the order Rickettsiales. ‘Candidatus M. mitochondrii’ is assigned on the basis of the 16S rRNA (AJ566640) and gyrB gene sequences (AM159536)” (p. 2539).

George Lucas gave his blessing to the Christening (of course he did).

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Acknowledgements: Thanks go to Ms. BBD who prevented me from making a fool of myself – this time – on the social media by pointing out to me that midichloria are real and that they are a mitochondrial parasite.

REFERENCE: Sassera D, Beninati T, Bandi C, Bouman EA, Sacchi L, Fabbi M, Lo N. (Nov. 2006). ‘Candidatus Midichloria mitochondrii’, an endosymbiont of the tick Ixodes ricinus with a unique intramitochondrial lifestyle. International Journal of Systematic and Evolutionary Microbiology, 56(Pt 11): 2535-2540. PMID: 17082386, DOI: 10.1099/ijs.0.64386-0. ABSTRACT | FREE FULLTEXT PDF 

By Neuronicus, 29 July 2017

Pic of the Day: Neil on teaching creationism

Dr. deGrasse Tyson’s picture is from Wikimedia released under PD and the quote is from a “Letter to the Editor” of New York Times retrieved from the Hayden Planetarium website on Nov. 2, 2016.