Molecular phylogeny of diplomonads and enteromonads based on SSU rRNA, alpha-tubulin and HSP90 genes: Implications for the evolutionary history of the double karyomastigont of diplomonads

<p>Abstract</p> <p>Background</p> <p>Fornicata is a relatively recently established group of protists that includes the diplokaryotic diplomonads (which have two similar nuclei per cell), and the monokaryotic enteromonads, retortamonads and <it>Carpediemonas</it>, with the more typical one nucleus per cell. The monophyly of the group was confirmed by molecular phylogenetic studies, but neither the internal phylogeny nor its position on the eukaryotic tree has been clearly resolved.</p> <p>Results</p> <p>Here we have introduced data for three genes (SSU rRNA, α-tubulin and HSP90) with a wide taxonomic sampling of Fornicata, including ten isolates of enteromonads, representing the genera <it>Trimitus </it>and <it>Enteromonas</it>, and a new undescribed enteromonad genus. The diplomonad sequences formed two main clades in individual gene and combined gene analyses, with <it>Giardia </it>(and <it>Octomitus</it>) on one side of the basal divergence and <it>Spironucleus</it>, <it>Hexamita </it>and <it>Trepomonas </it>on the other. Contrary to earlier evolutionary scenarios, none of the studied enteromonads appeared basal to diplokaryotic diplomonads. Instead, the enteromonad isolates were all robustly situated within the second of the two diplomonad clades. Furthermore, our analyses suggested that enteromonads do not constitute a monophyletic group, and enteromonad monophyly was statistically rejected in 'approximately unbiased' tests of the combined gene data.</p> <p>Conclusion</p> <p>We suggest that all higher taxa intended to unite multiple enteromonad genera be abandoned, that <it>Trimitus </it>and <it>Enteromonas </it>be considered as part of Hexamitinae, and that the term 'enteromonads' be used in a strictly utilitarian sense. Our result suggests either that the diplokaryotic condition characteristic of diplomonads arose several times independently, or that the monokaryotic cell of enteromonads originated several times independently by secondary reduction from the diplokaryotic state. Both scenarios are evolutionarily complex. More comparative data on the similarity of the genomes of the two nuclei of diplomonads will be necessary to resolve which evolutionary scenario is more probable.</p

Revision of the phylogeny of Placididea (Stramenopiles): Molecular and morphological diversity of novel placidid protists from extreme aquatic environments

Recent studies suggested that the diversity of microbial eukaryotes in hypersaline environments is widely underestimated. Placidids are a group of heterotrophic stramenopile flagellates that are frequently found in these environments, but up to now only very few species were isolated and fully described, mostly from marine or brackish water sites. In this study, we extend the known diversity of Placididea by three new genera (Allegra, Haloplacidia, and Placilonga) compromising nine new species, isolated from athalassic, mostly hypersaline environments (Allegra dunaii, Allegra atacamiensis, Allegra hypersalina, Haloplacidia cosmopolita, Suigetsumonas keniensis) and marine waters (Placilonga atlantica, Placidia azorensis, Placidia abyssalis, Wobblia pacifica) including a description of their morphology and molecular phylogeny. In total, 36 strains were comparatively analysed. Studies from athalassic waters revealed an especially high number of different genotypes. A multi gene analysis based on a ten genes dataset revealed a clear separation into marine, athalassic and brackish water clades. Several representatives were found to cope with hypersaline conditions from 20 to 250 PSU, even up to 284 PSU, suggesting that they may form a halotolerant group. (C) 2021 Elsevier GmbH. All rights reserved

Maximum likelihood tree of Fornicata based on SSU rRNA genes (GTR Γ I model)

Statistical support – ML bootstraps/RELL bootstraps/ML distance bootstraps/Bayesian posterior probability. Isolate PYX was identical in sequence with isolate PSEUD. Isolate PYX was therefore not included in the analysis but added to the tree by hand. Bootstrap support values <p><b>Copyright information:</b></p><p>Taken from "Molecular phylogeny of diplomonads and enteromonads based on SSU rRNA, alpha-tubulin and HSP90 genes: Implications for the evolutionary history of the double karyomastigont of diplomonads"</p><p>http://www.biomedcentral.com/1471-2148/8/205</p><p>BMC Evolutionary Biology 2008;8():205-205.</p><p>Published online 15 Jul 2008</p><p>PMCID:PMC2496913.</p><p></p

Maximum likelihood tree of the Hexamitinae-enteromonad clade based on SSU rRNA genes (GTR Γ I), rooted as per Figure 1

Statistical support – ML bootstraps/RELL bootstraps/ML distance bootstraps/Bayesian posterior probability. Isolate PYX was identical in sequence with isolate PSEUD. Isolate PYX was therefore not included in the analysis but added to the tree by hand. Bootstrap support values <p><b>Copyright information:</b></p><p>Taken from "Molecular phylogeny of diplomonads and enteromonads based on SSU rRNA, alpha-tubulin and HSP90 genes: Implications for the evolutionary history of the double karyomastigont of diplomonads"</p><p>http://www.biomedcentral.com/1471-2148/8/205</p><p>BMC Evolutionary Biology 2008;8():205-205.</p><p>Published online 15 Jul 2008</p><p>PMCID:PMC2496913.</p><p></p

Molecular phylogeny of diplomonads and enteromonads based on SSU rRNA, alpha-tubulin and HSP90 genes: Implications for the evolutionary history of the double karyomastigont of diplomonads-0

arrest of cytokinesis. The cell does not divide after the first karyokinesis and secondary karyokinesis results in a cell with four karyomastigonts. This cell then divides into two cells, each with a double karyomastigont. C. Model of evolutionary change from double karyomastigont morphology to single karyomastigont morphology, either by cytokinesis without karyokinesis, or by fusion of nuclei. (modified from Siddall, Hong and Desser 1992).<p><b>Copyright information:</b></p><p>Taken from "Molecular phylogeny of diplomonads and enteromonads based on SSU rRNA, alpha-tubulin and HSP90 genes: Implications for the evolutionary history of the double karyomastigont of diplomonads"</p><p>http://www.biomedcentral.com/1471-2148/8/205</p><p>BMC Evolutionary Biology 2008;8():205-205.</p><p>Published online 15 Jul 2008</p><p>PMCID:PMC2496913.</p><p></p

The Marine Microbial Eukaryote Transcriptome Sequencing Project (MMETSP): illuminating the functional diversity of eukaryotic life in the oceans through transcriptome sequencing.

Current sampling of genomic sequence data from eukaryotes is relatively poor, biased, and inadequate to address important questions about their biology, evolution, and ecology; this Community Page describes a resource of 700 transcriptomes from marine microbial eukaryotes to help understand their role in the world's oceans