“Candidatus Hafkinia simulans” gen. nov., sp. nov., a Novel Holospora-Like Bacterium from the Macronucleus of the Rare Brackish Water Ciliate Frontonia salmastra (Oligohymenophorea, Ciliophora): Multidisciplinary Characterization of the New Endosymbiont and Its Host

Abstract

We characterized a novel Holospora-like bacterium (HLB) (Alphaproteobacteria, Holosporales) living in the macronucleus of the brackish water ciliate Frontonia salmastra. This bacterium was morphologically and ultrastructurally investigated, and its life cycle and infection capabilities were described. We also obtained its 16S rRNA gene sequence and performed in situ hybridization experiments with a specifically-designed probe. A new taxon, BCandidatus Hafkinia simulans^, was established for this HLB. The phylogeny of the family Holosporaceae based on 16S rRNA gene sequences was inferred, adding to the already available data both the sequence of the novel bacterium and those of other Holospora and HLB species recently characterized. Our phylogenetic analysis provided molecular support for the monophyly of HLBs and placed the new endosymbiont as the sister genus of Holospora. Additionally, the host ciliate F. salmastra, recorded in Europe for the first time, was concurrently described through a multidisciplinary study. Frontonia salmastra's phylogenetic position in the subclass Peniculia and the genus Frontonia was assessed according to 18S rRNA gene sequencing. Comments on the biodiversity of this genus were added according to past and recent literature.

Outwitting planarian’s antibacterial defence mechanisms:Rickettsialesbacterial trans-infection fromParamecium multimicronucleatumto planarians

“…the probe Trichorick_142 (5’-GTTTCCAAATGTTATTCCATAC-3’) [28] in combination with the eubacterial universal probe EUB338 [86]. The experiments followed the protocol by [87] employing a hybridization buffer containing no formamide, according to the recommendations for the used probes. Slides were mounted with SlowFade Gold Antifade with DAPI (Invitrogen, Carlsbad, USA) and viewed with a Zeiss AxioPlan fluorescence microscope (Carl Zeiss, Oberkochen, Germany) equipped with an HBO 100W/2 mercuric vapor lamp.…”

“Candidatus Trichorickettsia mobilis”, a Rickettsiales bacterium, can be transiently transferred from the unicellular eukaryote Paramecium to the planarian Dugesia japonica

“…Trichorickettsia mobilis'', a second FISH experiment was carried out using a species-specific probe, i.e., the probe Trichorick_142 (5 -GTTTCCAAATGTTATTCCATAC-3 ) (Vannini et al, 2014) in combination with the bacterial universal probe EUB338 (Amann et al, 1990). The experiments followed the protocol by Fokin et al (2019) employing a hybridization buffer containing no formamide, according to the recommendations for the used probes. Slides were mounted with SlowFade Gold Antifade with DAPI (Invitrogen, Carlsbad, USA) and viewed with a Zeiss AxioPlan fluorescence microscope (Carl Zeiss, Oberkochen, Germany) equipped with an HBO 100W/2 mercuric vapor lamp.…”

Multidisciplinary investigation on the catfish parasite Hamatopeduncularia Yamaguti, 1953 (Monogenoidea: Dactylogyridae): description of two new species from India, and phylogenetic considerations

“…Ribosomal RNA genes are generally considered useful markers to study molecular taxonomy and phylogeny of both prokaryotic (e.g. Ferrantini et al 2009;Castelli et al 2018a,b;Chiellini et al 2019;Fokin et al 2019;Lanzoni et al 2019) and eukaryotic organisms (e.g. Modeo et al 2013a,b;Nitla et al 2018;Fokin et al 2019), parasitic metazoans included (e.g.…”

“…Ferrantini et al 2009;Castelli et al 2018a,b;Chiellini et al 2019;Fokin et al 2019;Lanzoni et al 2019) and eukaryotic organisms (e.g. Modeo et al 2013a,b;Nitla et al 2018;Fokin et al 2019), parasitic metazoans included (e.g. Blair & Barker 1993;Zhu et al 1998;Caffara et al 2016;Sailaja et al 2016;Mendoza-Franco et al 2018;Tedesco et al 2018).…”