Phylogenomics of neglected flagellated protists supports a revised eukaryotic tree of life.

Eukaryotes evolved from prokaryotic predecessors in the early Proterozoic and radiated from their already complex last common ancestor, diversifying into several supergroups with unresolved deep evolutionary connections. They evolved extremely diverse lifestyles, playing crucial roles in the carbon cycle. Heterotrophic flagellates are arguably the most diverse eukaryotes and often occupy basal positions in phylogenetic trees.

Transcriptomics of Diphyllatea (CRuMs) from South Pacific crater lakes confirm new cryptic clades.

The Diphyllatea (CRuMs) are heterotrophic protists currently divided into three distinct clades (Diphy I-III). Diphy I are biflagellates in the genus Diphylleia, whereas Diphy II and III represent cryptic clades comprising Collodictyon-type quadriflagellates that were recently distinguished based on rRNA gene phylogenies. Here, we isolated Diphyllatea from freshwater crater lakes on two South Pacific islands and generated high-quality transcriptomes from species representing each clade, including the first transcriptomic data from Diphy III.

One high quality genome and two transcriptome datasets for new species of Mantamonas, a deep-branching eukaryote clade.

Mantamonads were long considered to represent an "orphan" lineage in the tree of eukaryotes, likely branching near the most frequently assumed position for the root of eukaryotes. Recent phylogenomic analyses have placed them as part of the "CRuMs" supergroup, along with collodictyonids and rigifilids. This supergroup appears to branch at the base of Amorphea, making it of special importance for understanding the deep evolutionary history of eukaryotes.

Molecular and morphological characterization of four new ancyromonad genera and proposal for an updated taxonomy of the Ancyromonadida.

Ancyromonads are small biflagellated protists with a bean-shaped morphology. They are cosmopolitan in marine, freshwater, and soil environments, where they attach to surfaces while feeding on bacteria. These poorly known grazers stand out by their uncertain phylogenetic position in the tree of eukaryotes, forming a deep-branching "orphan" lineage that is considered key to a better understanding of the early evolution of eukaryotes.

Maturases and Group II Introns in the Mitochondrial Genomes of the Deepest Jakobid Branch.

Ophirinina is a recently described suborder of jakobid protists (Excavata) with only one described species to date, Ophirina amphinema. Despite the acquisition and analysis of massive transcriptomic and mitogenomic sequence data from O. amphinema, its phylogenetic position among excavates remained inconclusive, branching as sister group either to all Jakobida or to all Discoba.

Expanding the molecular and morphological diversity of Apusomonadida, a deep-branching group of gliding bacterivorous protists.

Apusomonads are cosmopolitan bacterivorous biflagellate protists usually gliding on freshwater and marine sediment or wet soils. These nanoflagellates form a sister lineage to opisthokonts and may have retained ancestral features helpful to understanding the early evolution of this large supergroup. Although molecular environmental analyses indicate that apusomonads are genetically diverse, few species have been described.

Phylogenomics Supports the Monophyly of Aphelids and Fungi and Identifies New Molecular Synapomorphies.

The supergroup Holomycota, composed of Fungi and several related lineages of unicellular organisms (Nucleariida, Rozellida, Microsporidia, and Aphelida), represents one of the major branches in the phylogeny of eukaryotes. Nevertheless, except for the well-established position of Nucleariida as the first holomycotan branch to diverge, the relationships among the other lineages have so far remained unresolved largely owing to the lack of molecular data for some groups. This was notably the case aphelids, a poorly known group of endobiotic phagotrophic protists that feed on algae with cellulose walls.

On the Biology, Diversity and Evolution of Nucleariid Amoebae (Amorphea, Obazoa, Opisthokonta.

Nucleariids are a small group of free-living heterotrophic amoebae. Although these organisms present a variety of cell sizes and cell coverings, they are mostly spherical cells with radiating filopodia, sometimes with several nuclei. Nuclearia, the genus that gives the name to the group, contains species that are opportunistic consumers of detritus, bacteria, and algae.

A phylogenetic and proteomic reconstruction of eukaryotic chromatin evolution.

Histones and associated chromatin proteins have essential functions in eukaryotic genome organization and regulation. Despite this fundamental role in eukaryotic cell biology, we lack a phylogenetically comprehensive understanding of chromatin evolution. Here, we combine comparative proteomics and genomics analysis of chromatin in eukaryotes and archaea.

Phylogenomics of a new fungal phylum reveals multiple waves of reductive evolution across Holomycota.

Compared to multicellular fungi and unicellular yeasts, unicellular fungi with free-living flagellated stages (zoospores) remain poorly known and their phylogenetic position is often unresolved. Recently, rRNA gene phylogenetic analyses of two atypical parasitic fungi with amoeboid zoospores and long kinetosomes, the sanchytrids Amoeboradix gromovi and Sanchytrium tribonematis, showed that they formed a monophyletic group without close affinity with known fungal clades. Here, we sequence single-cell genomes for both species to assess their phylogenetic position and evolution.

Combined cultivation and single-cell approaches to the phylogenomics of nucleariid amoebae, close relatives of fungi.

Nucleariid amoebae (Opisthokonta) have been known since the nineteenth century but their diversity and evolutionary history remain poorly understood. To overcome this limitation, we have obtained genomic and transcriptomic data from three , two and one species using traditional culturing and single-cell genome (SCG) and single-cell transcriptome amplification methods. The phylogeny of the complete 18S rRNA sequences of and confirmed their suggested evolutionary relatedness to nucleariid amoebae, although with moderate support for internal splits.

Global transcriptome analysis of the aphelid supports the phagotrophic origin of fungi.

Aphelids are little-known phagotrophic parasites of algae whose life cycle and morphology resemble those of the parasitic rozellids (Cryptomycota, Rozellomycota). In previous phylogenetic analyses of RNA polymerase and rRNA genes, aphelids, rozellids and Microsporidia (parasites of animals) formed a clade, named Opisthosporidia, which appeared as the sister group to Fungi. However, the statistical support for the Opisthosporidia was always moderate.

Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes.

This revision of the classification of eukaryotes follows that of Adl et al., 2012 [J. Euk.

Evolutionary Genomics of Metchnikovella incurvata (Metchnikovellidae): An Early Branching Microsporidium.

Metchnikovellids are highly specialized hyperparasites, which infect and reproduce inside gregarines (Apicomplexa) inhabiting marine invertebrates. Their phylogenetic affiliation was under constant discussion until recently, when analysis of the first near-complete metchnikovellid genome, that of Amphiamblys sp., placed it in a basal position with respect to most Microsporidia.

Parvularia atlantis gen. et sp. nov., a Nucleariid Filose Amoeba (Holomycota, Opisthokonta).

The opisthokonts constitute a eukaryotic supergroup divided into two main clades: the holozoans, which include animals and their unicellular relatives, and the holomycotans, which include fungi, opisthosporidians, and nucleariids. Nucleariids are phagotrophic filose amoebae that phenotypically resemble more their distant holozoan cousins than their holomycotan phylogenetic relatives. Despite their evolutionary interest, the diversity and internal phylogenetic relationships within the nucleariids remain poorly studied.

Dynamics of genomic innovation in the unicellular ancestry of animals.

Which genomic innovations underpinned the origin of multicellular animals is still an open debate. Here, we investigate this question by reconstructing the genome architecture and gene family diversity of ancestral premetazoans, aiming to date the emergence of animal-like traits. Our comparative analysis involves genomes from animals and their closest unicellular relatives (the Holozoa), including four new genomes: three Ichthyosporea and .

Molecular Phylogeny of Paraphelidium letcheri sp. nov. (Aphelida, Opisthosporidia).

Aphelids remain poorly known parasitoids of algae and have recently raised considerable interest due to their phylogenetic position at the base of Holomycota. Together with Cryptomycota (Rozellosporidia) and Microsporidia, they have been recently re-classified as the Opisthosporidia, which constitutes the sister group to the fungi within the Holomycota. Molecular environmental studies have revealed a huge diversity of aphelids, but only four genera have been described: Aphelidium, Amoeboaphelidium, Paraphelidium, and Pseudaphelidium.

Phylogenetic and ecological diversity of apusomonads, a lineage of deep-branching eukaryotes.

Apusomonads are a mysterious group of heterotrophic gliding biflagellates branching deeply in the eukaryotic tree of life as sister group to opisthokonts (including animals, fungi, and a variety of unicellular protists). Despite their evolutionary interest, their diversity and ecology remain largely unknown, with very few described species and environmental sequences in databases. Most environmental 18S rRNA gene-based studies generally fail to identify apusomonad sequences, which might be due to primer bias, low abundance, and/or to the fact that their biotopes remain poorly explored.

Morphological and Genetic Diversity of Opisthosporidia: New Aphelid Paraphelidium tribonemae gen. et sp. nov.

Aphelids are a poorly known group of parasitoids of algae that have raised considerable interest due to their pivotal phylogenetic position. Together with Cryptomycota and the highly derived Microsporidia, they have been recently re-classified as the Opisthosporidia, which constitute the sister group to the fungi within the Holomycota. Despite their huge diversity, as revealed by molecular environmental studies, and their phylogenetic interest, only three genera have been described (Aphelidium, Amoeboaphelidium, and Pseudaphelidium), from which 18S rRNA gene sequences exist only for Amoeboaphelidium and Aphelidium species.

Phylogenomics Reveals Convergent Evolution of Lifestyles in Close Relatives of Animals and Fungi.

The Opisthokonta are a eukaryotic supergroup divided in two main lineages: animals and related protistan taxa, and fungi and their allies [1, 2]. There is a great diversity of lifestyles and morphologies among unicellular opisthokonts, from free-living phagotrophic flagellated bacterivores and filopodiated amoebas to cell-walled osmotrophic parasites and saprotrophs. However, these characteristics do not group into monophyletic assemblages, suggesting rampant convergent evolution within Opisthokonta.

Bacterial proteins pinpoint a single eukaryotic root.

The large phylogenetic distance separating eukaryotic genes and their archaeal orthologs has prevented identification of the position of the eukaryotic root in phylogenomic studies. Recently, an innovative approach has been proposed to circumvent this issue: the use as phylogenetic markers of proteins that have been transferred from bacterial donor sources to eukaryotes, after their emergence from Archaea. Using this approach, two recent independent studies have built phylogenomic datasets based on bacterial sequences, leading to different predictions of the eukaryotic root.

Earliest Holozoan expansion of phosphotyrosine signaling.

Phosphotyrosine (pTyr) signaling is involved in development and maintenance of metazoans' multicellular body through cell-to-cell communication. Tyrosine kinases (TKs), tyrosine phosphatases, and other proteins relaying the signal compose the cascade. Domain architectures of the pTyr signaling proteins are diverse in metazoans, reflecting their complex intercellular communication.

Transcription factor evolution in eukaryotes and the assembly of the regulatory toolkit in multicellular lineages.

Transcription factors (TFs) are the main players in transcriptional regulation in eukaryotes. However, it remains unclear what role TFs played in the origin of all of the different eukaryotic multicellular lineages. In this paper, we explore how the origin of TF repertoires shaped eukaryotic evolution and, in particular, their role into the emergence of multicellular lineages.

Early evolution of the T-box transcription factor family.

Developmental transcription factors are key players in animal multicellularity, being members of the T-box family that are among the most important. Until recently, T-box transcription factors were thought to be exclusively present in metazoans. Here, we report the presence of T-box genes in several nonmetazoan lineages, including ichthyosporeans, filastereans, and fungi.