This study shows that ciliates can break species barriers through recurrent horizontal gene transfer from highly divergent lineages, resulting in viable offspring.

bioRxiv · Sep 30, 2026 · PreprintEvolutionary Biology

The tiny germline chromosomes of Paramecium aurelia have anexceptionally high recombination rate and are capped by a new class of Helitrons

Olivier Arnaiz, Frédéric Guèrin, Arnaud Couloux, Caridad Miró-Pina, Guillaume Pellerin, Irina Nekrasova, Joëlle Amselem, Jean‐Marc Aury, Simran Bhullar, Andrea Frapporti, Emmanuelle Lerat, Isabelle Luyten, Sophie Malinsky, Nathalie Mathy, Alexey A. Potekhin, , Linda Sperling

The paper reports the genome of Paramecium aurelia, revealing tiny germline chromosomes with an exceptionally high recombination rate and a new class of Helitrons at their ends.

BMC Biology · Apr 16, 2026Peer-reviewedGenomics

A developmental condensin I complex assists the Paramecium PiggyMac domesticated transposase during programmed DNA elimination

Thomas Balan, Mélanie Bazin-Gelis, Marc Guérineau, Valerio Vitali, Coralie Zangarelli, Olivier Arnaiz, Louise Abbou, Abdulwahab Altair, Amenaide Boutte du Jonchay, Aurelie Camprodon, Marina Giovannetti, Camille Poitrenaud, Emma Schumacher, Julien Bischerour, Anne‐Marie Tassin, , Mireille Bétermier

HAL · Apr 13, 2026Peer-reviewedMolecular Biology

A histone methyltransferase-independent function of PRC2 controls small RNA dynamics during programmed DNA elimination in Paramecium

Caridad Miró-Pina, Olivia Charmant, Marina Giovannetti, Augustin de Vanssay, Andrea Frapporti, Adeline Humbert, Maoussi Lhuillier‐Akakpo, Guillaume Chevreux, Olivier Arnaiz, Sandra Duharcourt

The paper shows PRC2 controls small RNA dynamics during DNA elimination in Paramecium by selectively degrading non-TE scnRNAs, independent of its histone methyltransferase activity.

Nucleic Acids Research · Sep 27, 2025Peer-reviewedGenomics

The nuclear PIWI-interacting protein Gtsf1 controls the selective degradation of small RNAs in Paramecium

Olivia Charmant, Julita Gruchota, Olivier Arnaiz, Katarzyna P Nowak, N. Moisan, Coralie Zangarelli, Mireille Bétermier, Anna Anielska-Mazur, Véronique Legros, Guillaume Chevreux, J Nowak, Sandra Duharcourt

The paper identifies Gtsf1 as essential for selecting and degrading small RNAs in Paramecium, ensuring proper genome elimination during macronucleus development.

Nucleic Acids Research · Oct 21, 2024Peer-reviewedGenetics

A development-specific POLX essential for programmed genome rearrangement in Paramecium tetraurelia

Baptiste Verron, Olivier Arnaiz, Coralie Zangarelli, Nathalie Mathy, Mireille Bétermier, Julien Bischerour

This study identifies PolX enzymes as essential for processing DNA ends during programmed genome rearrangement in Paramecium tetraurelia, revealing their role in NHEJ and IES excision.

bioRxiv · Jul 18, 2024 · PreprintMolecular Biology

Inter-generational nuclear crosstalk links the control of gene expression to programmed genome rearrangements during the Paramecium sexual cycle

Mélanie Bazin-Gelis, Evangelia Eleftheriou, Coralie Zangarelli, Gaëlle Lelandais, Linda Sperling, Olivier Arnaiz, Mireille Bétermier

Nucleic Acids Research · Oct 23, 2023Peer-reviewedGenomics

Developmental timing of programmed DNA elimination in Paramecium tetraurelia recapitulates germline transposon evolutionary dynamics

Coralie Zangarelli, Olivier Arnaiz, Mickaël Bourge, Kévin Gorrichon, Yan Jaszczyszyn, Nathalie Mathy, Escoriza Loïc, Mireille Bétermier, Vinciane Régnier

The paper determines the developmental timing of DNA elimination in Paramecium tetraurelia and links it to the evolutionary dynamics of germline transposons.

Genome Research · Nov 1, 2022Peer-reviewedGenomics

GC content but not nucleosome positioning directly contributes to intron-splicing efficiency in Paramecium

Stefano Gnan, Mélody Matelot, Marion Weiman, Olivier Arnaiz, Frédéric Guèrin, Linda Sperling, Mireille Bétermier, Claude Thermes, Chun-Long Chen, Sandra Duharcourt

Genome Research · Apr 1, 2022Peer-reviewedGenomics

Paramecium Polycomb Repressive Complex 2 physically interacts with the small RNA binding PIWI protein to repress transposable elements

Caridad Miró-Pina, Takayuki Kawaguchi, Olivia Charmant, Audrey Michaud, Isadora S. Cohen, Adeline Humbert, Yan Jaszczyszyn, Laurence Del Maestro, Daniel Holoch, Slimane Ait‐Si‐Ali, Olivier Arnaiz, Raphaël Margueron, Sandra Duharcourt

The paper identifies PRC2 cofactors that mediate small RNA recruitment to repress transposable elements in Paramecium.

bioRxiv · Aug 12, 2021 · PreprintMolecular Biology

Massive colonization of protein-coding exons by selfish genetic elements in Paramecium germline genomes

Diamantis Sellis, Frédéric Guèrin, Olivier Arnaiz, Walker Pett, Emmanuelle Lerat, Nicole Boggetto, Sascha Krenek, Thomas Ulrich Berendonk, Arnaud Couloux, Jean‐Marc Aury, Karine Labadie, Sophie Malinsky, Simran Bhullar, Éric Meyer, Linda Sperling, , Sandra Duharcourt

The paper investigates the evolutionary origin of Internal Eliminated Sequences (IESs) in Paramecium genomes, showing transposable elements drive their proliferation and diversification.

PLoS Biology · Jul 29, 2021Peer-reviewedGenomics