Verni, Franco


Publications (8)

Morphology, ultrastructure, genomics, and phylogeny of Euplotes vanleeuwenhoeki sp. nov. and its ultra-reduced endosymbiont “Candidatus Pinguicoccus supinus” sp. nov.

Citation
Serra et al. (2020). Scientific Reports 10 (1)
Names
Ca. Pinguicoccus supinus
Subjects
Multidisciplinary
Abstract
AbstractTaxonomy is the science of defining and naming groups of biological organisms based on shared characteristics and, more recently, on evolutionary relationships. With the birth of novel genomics/bioinformatics techniques and the increasing interest in microbiome studies, a further advance of taxonomic discipline appears not only possible but highly desirable. The present work proposes a new approach to modern taxonomy, consisting in the inclusion of novel descriptors in the organism characterization: (1) the presence of associated microorganisms (e.g.: symbionts, microbiome), (2) the mitochondrial genome of the host, (3) the symbiont genome. This approach aims to provide a deeper comprehension of the evolutionary/ecological dimensions of organisms since their very first description. Particularly interesting, are those complexes formed by the host plus associated microorganisms, that in the present study we refer to as “holobionts”. We illustrate this approach through the description of the ciliateEuplotes vanleeuwenhoekisp. nov. and its bacterial endosymbiont “CandidatusPinguicoccus supinus” gen. nov., sp. nov. The endosymbiont possesses an extremely reduced genome (~ 163 kbp); intriguingly, this suggests a high integration between host and symbiont.

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

Citation
Modeo et al. (2020). PeerJ 8
Names
Ca. Trichorickettsia mobilis
Subjects
General Agricultural and Biological Sciences General Biochemistry, Genetics and Molecular Biology General Medicine General Neuroscience
Abstract
Most of the microorganisms responsible for vector-borne diseases (VBD) have hematophagous arthropods as vector/reservoir. Recently, many new species of microorganisms phylogenetically related to agents of VBD were found in a variety of aquatic eukaryotic hosts; in particular, numerous new bacterial species related to the genus Rickettsia (Alphaproteobacteria, Rickettsiales) were discovered in protist ciliates and other unicellular eukaryotes. Although their pathogenicity for humans and terrestrial animals is not known, several indirect indications exist that these bacteria might act as etiological agents of possible VBD of aquatic organisms, with protists as vectors. In the present study, a novel strain of the Rickettsia-Like Organism (RLO) endosymbiont “Candidatus (Ca.) Trichorickettsia mobilis” was identified in the macronucleus of the ciliate Paramecium multimicronucleatum. We performed transfection experiments of this RLO to planarians (Dugesia japonica) per os. Indeed, the latter is a widely used model system for studying bacteria pathogenic to humans and other Metazoa. In transfection experiments, homogenized paramecia were added to food of antibiotic-treated planarians. Treated and non-treated (i.e. control) planarians were investigated at day 1, 3, and 7 after feeding for endosymbiont presence by means of PCR and ultrastructural analyses. Obtained results were fully concordant and suggest that this RLO endosymbiont can be transiently transferred from ciliates to metazoans, being detected up to day 7 in treated planarians’ enterocytes. Our findings might offer insights into the potential role of ciliates or other protists as putative vectors for diseases caused by Rickettsiales or other RLOs and occurring in fish farms or in the wild.

“ Candidatus Anadelfobacter veles” and “ Candidatus Cyrtobacter comes,” Two New Rickettsiales Species Hosted by the Protist Ciliate Euplotes harpa (Ciliophora, Spirotrichea)

Citation
Vannini et al. (2010). Applied and Environmental Microbiology 76 (12)
Names
Ca. Cyrtobacter comes Ca. Anadelfobacter veles
Subjects
Applied Microbiology and Biotechnology Biotechnology Ecology Food Science
Abstract
ABSTRACT The order Rickettsiales ( Alphaproteobacteria ) is a well-known group containing obligate endocellular prokaryotes. The order encompasses three families ( Rickettsiaceae , Anaplasmataceae , and Holosporaceae ) and a fourth, family-level cluster, which includes only one candidate species, “ Candidatus Midichloria mitochondrii,” as well as several unnamed bacterial symbionts. The broad host range exhibited by the members of the “ Candidatus Midichloria” clade suggests their eventual relevance for a better understanding of the evolution of symbiosis and host specificity of Rickettsiales . In this paper, two new bacteria belonging to the “ Candidatus Midichloria” clade, hosted by two different strains of the ciliate protist Euplotes harpa , are described on the basis of ultrastructural observations, comparative 16S rRNA gene sequence analysis, and an estimation of the percentage of infection. Ultrastructure of these bacteria shows some unusual features: one has an electron-dense cytoplasm, and the other one lacks a symbiosomal membrane. The latter was up to now considered an exclusive feature of bacteria belonging to the family Rickettsiaceae . 16S rRNA gene phylogenetic analysis unambiguously places the new bacteria in the “ Candidatus Midichloria” clade, although their phylogenetic relationships with other members of the clade are not clearly resolved. This is the first report of a ciliate-borne bacterium belonging to the “ Candidatus Midichloria” clade. On the basis of the data obtained, the two bacteria are proposed as two new candidate genera and species, “ Candidatus Anadelfobacter veles” and “ Candidatus Cyrtobacter comes.”