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cognitis nomina
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Authors Castelli

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Castelli, M.


Publications
2

CitationNamesAbstract
The extracellular association of the bacterium “CandidatusDeianiraea vastatrix” with the ciliateParameciumsuggests an alternative scenario for the evolution ofRickettsiales Castelli et al. (2018). Ca. Deianiraea vastatrix
Host and symbiont intraspecific variability: The case of Paramecium calkinsi and “ Candidatus Trichorickettsia mobilis” Sabaneyeva et al. (2018). European Journal of Protistology 62 Ca. Trichorickettsia mobilis

The extracellular association of the bacterium “CandidatusDeianiraea vastatrix” with the ciliateParameciumsuggests an alternative scenario for the evolution ofRickettsiales
AbstractRickettsialesare a lineage of obligatorily intracellularAlphaproteobacteria, encompassing important human pathogens, manipulators of host reproduction, and mutualists. Here we report the discovery of a novelRickettsialesbacterium associated withParamecium, displaying a unique extracellular lifestyle, including the ability to replicate outside host cells. Genomic analyses show that the bacterium possesses a higher capability to synthesize amino acids, compared to all investigatedRickettsiales. Considering these observations, phylogenetic and phylogenomic reconstructions, and re-evaluating the different means of interaction ofRickettsialesbacteria with eukaryotic cells, we propose an alternative scenario for the evolution of intracellularity inRickettsiales. According to our reconstruction, theRickettsialesancestor would have been an extracellular and metabolically versatile bacterium, while obligate intracellularity and genome reduction would have evolved later in parallel and independently in different sub-lineages. The proposed new scenario could impact on the open debate on the lifestyle of the last common ancestor of mitochondria withinAlphaproteobacteria.
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