Characterization of Skoliomonas gen. nov., a haloalkaliphilic anaerobe related to barthelonids (Metamonada).

Metamonads are a large and exclusively anaerobic group of protists. Additionally, they are one of the three clades proposed to ancestrally possess an "excavate" cell morphology, with a conspicuous ventral groove accompanied by a posterior flagellum with a vane. Here, we cultivate and characterize four anaerobic bacterivorous flagellates from hypersaline and alkaline soda lake environments, which represent a novel clade.

Extreme mitochondrial reduction in a novel group of free-living metamonads.

Metamonads are a diverse group of heterotrophic microbial eukaryotes adapted to living in hypoxic environments. All metamonads but one harbour metabolically altered 'mitochondrion-related organelles' (MROs) with reduced functions, however the degree of reduction varies. Here, we generate high-quality draft genomes, transcriptomes, and predicted proteomes for five recently discovered free-living metamonads.

Foraging mechanisms in excavate flagellates shed light on the functional ecology of early eukaryotes.

The phagotrophic flagellates described as "typical excavates" have been hypothesized to be morphologically similar to the Last Eukaryotic Common Ancestor and understanding the functional ecology of excavates may therefore help shed light on the ecology of these early eukaryotes. Typical excavates are characterized by a posterior flagellum equipped with a vane that beats in a ventral groove. Here, we combined flow visualization and observations of prey capture in representatives of the three clades of excavates with computational fluid dynamic modeling, to understand the functional significance of this cell architecture.

Contractile vacuoles: a rapidly expanding (and occasionally diminishing?) understanding.

Osmoregulation is the homeostatic mechanism essential for the survival of organisms in hypoosmotic and hyperosmotic conditions. In freshwater or soil dwelling protists this is frequently achieved through the action of an osmoregulatory organelle, the contractile vacuole. This endomembrane organelle responds to the osmotic challenges and compensates by collecting and expelling the excess water to maintain the cellular osmolarity.

Meteora sporadica, a protist with incredible cell architecture, is related to Hemimastigophora.

"Kingdom-level" branches are being added to the tree of eukaryotes at a rate approaching one per year, with no signs of slowing down. Some are completely new discoveries, whereas others are morphologically unusual protists that were previously described but lacked molecular data. For example, Hemimastigophora are predatory protists with two rows of flagella that were known since the 19 century but proved to represent a new deep-branching eukaryote lineage when phylogenomic analyses were conducted.

The function of the feeding groove of 'typical excavate' flagellates.

Phagotrophic flagellates are the main consumers of bacteria and picophytoplankton. Despite their ecological significance in the 'microbial loop', many of their predation mechanisms remain unclear. 'Typical excavates' bear a ventral groove, where prey is captured for ingestion.

Kaonashia insperata gen. et sp. nov., a eukaryotrophic flagellate, represents a novel major lineage of heterotrophic stramenopiles.

Eukaryotrophic protists are ecologically significant and possess characteristics key to understanding the evolution of eukaryotes; however, they remain poorly studied, due partly to the complexities of maintaining predator-prey cultures. Kaonashia insperata, gen. nov.

Characterisation and Cultivation of New Lineages of Colponemids, a Critical Assemblage for Inferring Alveolate Evolution.

There are several alveolate groups outside the well-studied trio - ciliates, dinoflagellates, and apicomplexans - that are crucial for understanding the evolution of this major taxon. One such assemblage is the "colponemids", which are eukaryotrophic biflagellates, usually with a ventral groove associated with the posterior flagellum. Previous phylogenetic studies show colponemids forming up to three distinct deep branches within alveolates (e.

Euglena International Network (EIN): Driving euglenoid biotechnology for the benefit of a challenged world.

Euglenoids (Euglenida) are unicellular flagellates possessing exceptionally wide geographical and ecological distribution. Euglenoids combine a biotechnological potential with a unique position in the eukaryotic tree of life. In large part these microbes owe this success to diverse genetics including secondary endosymbiosis and likely additional sources of genes.

Comparative transcriptomics reveals the molecular toolkit used by an algivorous protist for cell wall perforation.

Microbial eukaryotes display a stunning diversity of feeding strategies, ranging from generalist predators to highly specialized parasites. The unicellular "protoplast feeders" represent a fascinating mechanistic intermediate, as they penetrate other eukaryotic cells (algae and fungi) like some parasites but then devour their cell contents by phagocytosis. Besides prey recognition and attachment, this complex behavior involves the local, pre-phagocytotic dissolution of the prey cell wall, which results in well-defined perforations of species-specific size and structure.

Genomic analysis finds no evidence of canonical eukaryotic DNA processing complexes in a free-living protist.

Cells replicate and segregate their DNA with precision. Previous studies showed that these regulated cell-cycle processes were present in the last eukaryotic common ancestor and that their core molecular parts are conserved across eukaryotes. However, some metamonad parasites have secondarily lost components of the DNA processing and segregation apparatuses.

Description of the marine predator Sericomyxa perlucida gen. et sp. nov., a cultivated representative of the deepest branching lineage of vampyrellid amoebae (Vampyrellida, Rhizaria).

The vampyrellids (Vampyrellida, Rhizaria) are naked amoebae of considerable genetic diversity. Three families have been well-defined (Vampyrellidae, Leptophryidae, and Placopodidae), but most vampyrellid lineages detected by environmental sequencing are poorly known or completely uncharacterized. In the brackish sediment of Lake Bras D'Or, Nova Scotia, Canada, we discovered an amoeba with a vampyrellid-like life history that was morphologically dissimilar from previously known vampyrellid taxa.

Description of Imasa heleensis, gen. nov., sp. nov. (Imasidae, fam. nov.), a Deep-Branching Marine Malawimonad and Possible Key Taxon in Understanding Early Eukaryotic Evolution.

Malawimonadida is a deep-level (arguably "kingdom-scale") lineage of eukaryotes whose phylogenetic affinities are uncertain but of great evolutionary interest, as the group is suspected to branch close to the root of the tree of eukaryotes. Part of the difficulty in placing Malawimonadida phylogenetically is its tiny circumscription: at present, it comprises only two described and one cultured but undescribed species, all of them are freshwater suspension-feeding nanoflagellates. In this study, we cultivated and characterised Imasa heleensis gen.

EukRef-excavates: seven curated SSU ribosomal RNA gene databases.

The small subunit ribosomal RNA (SSU rRNA) gene is a widely used molecular marker to study the diversity of life. Sequencing of SSU rRNA gene amplicons has become a standard approach for the investigation of the ecology and diversity of microbes. However, a well-curated database is necessary for correct classification of these data.

Evolutionary History of Mitochondrial Genomes in Discoba, Including the Extreme Halophile Pleurostomum flabellatum (Heterolobosea).

Data from Discoba (Heterolobosea, Euglenozoa, Tsukubamonadida, and Jakobida) are essential to understand the evolution of mitochondrial genomes (mitogenomes), because this clade includes the most primitive-looking mitogenomes known, as well some extremely divergent genome information systems. Heterolobosea encompasses more than 150 described species, many of them from extreme habitats, but only six heterolobosean mitogenomes have been fully sequenced to date. Here we complete the mitogenome of the heterolobosean Pleurostomum flabellatum, which is extremely halophilic and reportedly also lacks classical mitochondrial cristae, hinting at reduction or loss of respiratory function.

The Molecular Diversity of Phagotrophic Euglenids Examined Using Single-cell Methods.

Euglenids are a diverse group of euglenozoan flagellates that includes phototrophs, osmotrophs, and phagotrophs. Despite making up most of the phylogenetic diversity of euglenids, phagotrophs remain understudied, and recent work has focused on 'deep-branching' groups. Spirocuta is the large clade encompassing all flexible euglenids including the phototroph and primary osmotroph clades, plus various phagotrophs.

Barthelonids represent a deep-branching metamonad clade with mitochondrion-related organelles predicted to generate no ATP.

We here report the phylogenetic position of barthelonids, small anaerobic flagellates previously examined using light microscopy alone. spp. were isolated from geographically distinct regions and we established five laboratory strains.

The New Tree of Eukaryotes.

For 15 years, the eukaryote Tree of Life (eToL) has been divided into five to eight major groupings, known as 'supergroups'. However, the tree has been profoundly rearranged during this time. The new eToL results from the widespread application of phylogenomics and numerous discoveries of major lineages of eukaryotes, mostly free-living heterotrophic protists.

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.

A single-cell genome reveals diplonemid-like ancestry of kinetoplastid mitochondrial gene structure.

Euglenozoa comprises euglenids, kinetoplastids, and diplonemids, with each group exhibiting different and highly unusual mitochondrial genome organizations. Although they are sister groups, kinetoplastids and diplonemids have very distinct mitochondrial genome architectures, requiring widespread insertion/deletion RNA editing and extensive -splicing, respectively, in order to generate functional transcripts. The evolutionary history by which these differing processes arose remains unclear.

Ecological and evolutionary patterns in the enigmatic protist genus Percolomonas (Heterolobosea; Discoba) from diverse habitats.

The heterotrophic flagellate Percolomonas cosmopolitus (Heterolobosea) is often observed in saline habitats worldwide, from coastal waters to saturated brines. However, only two cultures assigned to this morphospecies have been examined using molecular methods, and their 18S rRNA gene sequences are extremely different. Further the salinity tolerances of individual strains are unknown.

A natural toroidal microswimmer with a rotary eukaryotic flagellum.

We describe Idionectes vortex gen. nov., sp.

Ploeotids Represent Much of the Phylogenetic Diversity of Euglenids.

Ploeotids are an assemblage of rigid phagotrophic euglenids that have 10-12 pellicular strips and glide on their posterior flagellum. Molecular phylogenies place them as a poorly resolved, likely paraphyletic assemblage outside the Spirocuta clade of flexible euglenids, which includes the well-known phototrophs and primary osmotrophs. Here, we report SSU rRNA gene sequences from 38 ploeotids, using both single-cell and culture-based methods.