DOCSLIB.ORG

Phylogenomics Reshuffles the Eukaryotic Supergroups Fabien Burki1*, Kamran Shalchian-Tabrizi3, Marianne Minge3,A˚Smund Skjæveland3, Sergey I

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Phylogenomics Reshuffles the Eukaryotic Supergroups Fabien Burki1*, Kamran Shalchian-Tabrizi3, Marianne Minge3,A˚Smund Skjæveland3, Sergey I View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by PubMed Central Phylogenomics Reshuffles the Eukaryotic Supergroups Fabien Burki1*, Kamran Shalchian-Tabrizi3, Marianne Minge3,A˚smund Skjæveland3, Sergey I. Nikolaev2, Kjetill S. Jakobsen3, Jan Pawlowski1 1 Department of Zoology and Animal Biology, University of Geneva, Geneva, Switzerland, 2 Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland, 3 Department of Biology, University of Oslo, Oslo, Norway Background. Resolving the phylogenetic relationships between eukaryotes is an ongoing challenge of evolutionary biology. In recent years, the accumulation of molecular data led to a new evolutionary understanding, in which all eukaryotic diversity has been classified into five or six supergroups. Yet, the composition of these large assemblages and their relationships remain controversial. Methodology/Principle Findings. Here, we report the sequencing of expressed sequence tags (ESTs) for two species belonging to the supergroup Rhizaria and present the analysis of a unique dataset combining 29908 amino acid positions and an extensive taxa sampling made of 49 mainly unicellular species representative of all supergroups. Our results show a very robust relationship between Rhizaria and two main clades of the supergroup chromalveolates: stramenopiles and alveolates. We confirm the existence of consistent affinities between assemblages that were thought to belong to different supergroups of eukaryotes, thus not sharing a close evolutionary history. Conclusions. This well supported phylogeny has important consequences for our understanding of the evolutionary history of eukaryotes. In particular, it questions a single red algal origin of the chlorophyll-c containing plastids among the chromalveolates. We propose the abbreviated name ‘SAR’ (Stramenopiles+Alveolates+Rhizaria) to accommodate this new super assemblage of eukaryotes, which comprises the largest diversity of unicellular eukaryotes. Citation: Burki F, Shalchian-Tabrizi K, Minge M, Skjæveland A˚, Nikolaev SI, et al (2007) Phylogenomics Reshuffles the Eukaryotic Supergroups. PLoS ONE 2(8): e790. doi:10.1371/journal.pone.0000790 INTRODUCTION protein sequences led to two potential affiliations with other A well resolved phylogenetic tree describing the relationships eukaryotes. According to the first hypothesis, Rhizaria was sister among all organisms is one of the most important challenges of group to an excavate clade defined by G. lamblia, T. vaginalis, and modern evolutionary biology. A current hypothesis for the tree of Euglenozoa. The second hypothesis suggested that Rhizaria are eukaryotes proposes that all diversity can be classified into five or closely related to stramenopiles, which form together with six putative very large assemblages, the so-called ‘supergroups’ alveolates, haptophytes, and cryptophytes the supergroup of (reviewed in [1] and [2]). These comprise the ‘Opisthokonta’ and chromalveolates. Besides our study, the branching pattern between ‘Amoeboza’ (often united in the ‘Unikonts’), ‘Archaeplastida’ or Rhizaria and other supergroups has been specifically evaluated ‘Plantae’, ‘Excavata’, Chromalveolata’, and ‘Rhizaria’. The super- only by Hackett et al. (2007), who reported a robust relationship group concept as a whole, however, has been shown to be only between Rhizaria and members of the chromalveolates. moderately supported [3] and the evolutionary links among these Here, we further address the phylogenetic position of Rhizaria groups are yet to be confirmed. These uncertainties may be due to within the eukaryotic tree using an extensive multigene approach. the limited amounts of available data for the most parts of the For this purpose, we have carried out two expressed sequence tag eukaryotic diversity. In particular, only a small fraction of the (EST) surveys of rhizarian species: an undetermined foraminiferan unicellular eukaryote diversity [4] has been subject to molecular species belonging to the genus Quinqueloculina (574 unique studies, leading to important imbalances in phylogenies sequences, Accession Numbers: EV435154-EV435825) and Gym- and preventing researchers to reliably infer deep evolutionary nophrys cometa (628 unique sequences, Accession Numbers: relationships. EV434532-EV435153) (Cienkowski, 1876), a freshwater protist The supergroup Rhizaria [5] is particularly interesting for testing that has been shown to be part of core Cercozoa [20]. Using novel different possible scenarios of eukaryote evolution. This assemblage EST datasets for two rhizarians [21,22] and data from publicly has only recently been described and is based exclusively on available protists (TBestDB; http://tbestdb.bcm.umontreal.ca/ searches/login.php), we constructed a taxonomically broad dataset molecular data; nevertheless it is very well supported in most of 123 protein alignments amounting to nearly 30000 unambig- phylogenies [3]. It includes very diverse organisms such as filose testate amoeba, cercomonads, chlorarachniophytes (together, core Cercozoa), foraminifers, plasmodiophorids, haplosporidians, gro- Academic Editor: Geraldine Butler, University College Dublin, Ireland miids, and radiolarians (see [2] for an overview or [6–11]). In opposition to Rhizaria, the monophyly of Chromalveolata is far from Received June 17, 2007; Accepted July 26, 2007; Published August 29, 2007 being undisputed (see [12], or [3,13–15]). Chromalveolates were Copyright: ß 2007 Burki et al. This is an open-access article distributed under originally defined by their plastid of red algal origin that (when the terms of the Creative Commons Attribution License, which permits present) is believed to have arisen from a single secondary endo- unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. symbiosis [16]. This supergroup encompasses many ecologically important photosynthetic protists, including coccolithophorids Funding: This research was supported by the Swiss National Science Foundation (belonging to the haptophytes), cryptophytes, diatoms, brown grant 3100A0-100415 and 3100A0-112645 (JP); and by research grant (grant no 118894/431) from the Norwegian Research Council (KSJ). seaweeds (together, the chromists) and dinoflagellates (which form together with ciliates and apicomplexans the alveolates) [17,18]. Competing Interests: The authors have declared that no competing interests Using a phylogenomic approach we recently confirmed the exist. monophyly of Rhizaria and addressed the question of its * To whom correspondence should be addressed. E-mail: Fabien.Burki@zoo. evolutionary history [19]. The analyses of 85 concatenated nuclear unige.ch PLoS ONE | www.plosone.org 1 August 2007 | Issue 8 | e790 Reshuffling the Supergroups uously aligned amino acid positions. Our superalignment includes in the ML inference (68% and 61% BP, respectively) but 1.0 BiPP. several representatives for all described eukaryotic supergroups. Finally, alveolates, stramenopiles, and Rhizaria all formed mono- Our results show an unambiguous relationship between Rhizaria phyletic groups with 100% BP and 1.0 BiPP. Although most of the and stramenopiles, confirming the hypothesis we had previously recognized eukaryotic supergroups are recovered in our analyses, proposed and suggesting the emergence of a new super assemblage the relationships among them are generally not well resolved. This of eukaryotes that we propose to name ‘SAR’ (stramenopiles+al- is with two notable exceptions: the union of the unikonts and, veolates+Rhizaria). much more interestingly, the strongly supported (BP = 100%; BiPP = 1.0) assemblage of stramenopiles, Rhizaria, and alveolates RESULTS (clade SAR), with these last two groups being robustly clustered together (BP = 88%; BiPP = 1.0) (clade SR). Comparisons of Single-gene analyses and concatenation substitution rates between the different lineages were highly non 49 eukaryotic species representatives of all five current super- significant at 1.25%, indicating that all species evolve at very groups for which large amounts of data are available were selected. similar rates, thus rendering unlikely a possible artefact caused by We identified 123 genes (see Table S1) that fulfilled the following long branches (data not shown). criteria: 1) at least one of the four rhizarian species as well as at To further test this unexpected nested position of Rhizaria least one member of unikonts, plants, excavates, alveolates, and between alveolates and stramenopiles, we compared different stramenopiles were present in every single-gene alignment; 2) the topologies by performing the approximately unbiased (AU) test, orthology in every gene was unambiguous on the base of single- which is considered as the least-biased and most rigorous test genes bootstrapped maximum likelihood (ML) trees. This second available to date [30]. More precisely we evaluated two questions: criterion is particularly important in multigene analyses in order to 1) Are Rhizaria indeed monophyletic with stramenopiles and avoid the mixture of distant paralogs in concatenated alignments, alveolates; 2) Are Rhizaria specifically related to stramenopiles, because it would dilute the true phylogenetic signal by opposing with the exclusion of alveolates? Our analyses show that an strong mis-signals, thus preventing the recovering of deep alternative topology, which corresponded to the best topology with relationships [23]. Similarly, it
Load more

Recommended publications
  • Basal Body Structure and Composition in the Apicomplexans Toxoplasma and Plasmodium Maria E
    Francia et al. Cilia (2016) 5:3 DOI 10.1186/s13630-016-0025-5 Cilia REVIEW Open Access Basal body structure and composition in the apicomplexans Toxoplasma and Plasmodium Maria E. Francia1* , Jean‑Francois Dubremetz2 and Naomi S. Morrissette3 Abstract The phylum Apicomplexa encompasses numerous important human and animal disease-causing parasites, includ‑ ing the Plasmodium species, and Toxoplasma gondii, causative agents of malaria and toxoplasmosis, respectively. Apicomplexans proliferate by asexual replication and can also undergo sexual recombination. Most life cycle stages of the parasite lack flagella; these structures only appear on male gametes. Although male gametes (microgametes) assemble a typical 9 2 axoneme, the structure of the templating basal body is poorly defined. Moreover, the rela‑ tionship between asexual+ stage centrioles and microgamete basal bodies remains unclear. While asexual stages of Plasmodium lack defined centriole structures, the asexual stages of Toxoplasma and closely related coccidian api‑ complexans contain centrioles that consist of nine singlet microtubules and a central tubule. There are relatively few ultra-structural images of Toxoplasma microgametes, which only develop in cat intestinal epithelium. Only a subset of these include sections through the basal body: to date, none have unambiguously captured organization of the basal body structure. Moreover, it is unclear whether this basal body is derived from pre-existing asexual stage centrioles or is synthesized de novo. Basal bodies in Plasmodium microgametes are thought to be synthesized de novo, and their assembly remains ill-defined. Apicomplexan genomes harbor genes encoding δ- and ε-tubulin homologs, potentially enabling these parasites to assemble a typical triplet basal body structure.
    [Show full text]
  • Molecular Data and the Evolutionary History of Dinoflagellates by Juan Fernando Saldarriaga Echavarria Diplom, Ruprecht-Karls-Un
    Molecular data and the evolutionary history of dinoflagellates by Juan Fernando Saldarriaga Echavarria Diplom, Ruprecht-Karls-Universitat Heidelberg, 1993 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES Department of Botany We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA November 2003 © Juan Fernando Saldarriaga Echavarria, 2003 ABSTRACT New sequences of ribosomal and protein genes were combined with available morphological and paleontological data to produce a phylogenetic framework for dinoflagellates. The evolutionary history of some of the major morphological features of the group was then investigated in the light of that framework. Phylogenetic trees of dinoflagellates based on the small subunit ribosomal RNA gene (SSU) are generally poorly resolved but include many well- supported clades, and while combined analyses of SSU and LSU (large subunit ribosomal RNA) improve the support for several nodes, they are still generally unsatisfactory. Protein-gene based trees lack the degree of species representation necessary for meaningful in-group phylogenetic analyses, but do provide important insights to the phylogenetic position of dinoflagellates as a whole and on the identity of their close relatives. Molecular data agree with paleontology in suggesting an early evolutionary radiation of the group, but whereas paleontological data include only taxa with fossilizable cysts, the new data examined here establish that this radiation event included all dinokaryotic lineages, including athecate forms. Plastids were lost and replaced many times in dinoflagellates, a situation entirely unique for this group. Histones could well have been lost earlier in the lineage than previously assumed.
    [Show full text]
  • Denis BAURAIN Département Des Sciences De La Vie Université De Liège Société Royale Des Sciences De Liège 20 Septembre 2012 Plan De L’Exposé
    L’évolution des Eucaryotes Denis BAURAIN Département des Sciences de la Vie Université de Liège Société Royale des Sciences de Liège 20 septembre 2012 Plan de l’exposé 1. Qu’est-ce qu’un Eucaryote ? 2. Quelle est la diversité des Eucaryotes ? 3. Quelles sont les relations de parenté entre les grands groupes d’Eucaryotes ? 4. D’où viennent les Eucaryotes ? Qu’est-ce1 qu’un Eucaryote ? Eukaryotic Cells définition ultrastructurale : organelles spécifiques • noyau (1) • nucléole (2) • RE (5, 8) • Golgi (6) • centriole(s) (13) • mitochondrie(s) (9) • chloroplaste(s) • ... http://en.wikipedia.org/ A eukaryotic gene is arranged in a patchwork of coding (exons) and non-coding sequences (introns). Introns are eliminated while exons are spliced together to yield the mature mRNA used for protein synthesis. http://reflexions.ulg.ac.be/ Gene DNA Transcription Exon1 Exon2 Exon3 Exon4 Exon5 Exon6 pre-mRNA Alternatif splicing mature mRNA Translation Protein In many Eukaryotes, almost all genes can lead to different proteins through a process termed alternative splicing. http://reflexions.ulg.ac.be/ REVIEWS Box 2 | Endosymbiotic evolution and the tree of genomes Intracellular endosymbionts that originally descended from free-living prokaryotes have been important in the evolution of eukaryotes by giving rise to two cytoplasmic organelles. Mitochondria arose from α-proteobacteria and chloroplasts arose from cyanobacteria. Both organelles have made substantial contributions to the complement of genes that are found in eukaryotic nuclei today. The figure shows a schematic diagram of the evolution of eukaryotes, highlighting the incorporation of mitochondria and chloroplasts into the eukaryotic lineage through endosymbiosis and the subsequent co-evolution of the nuclear and organelle genomes.
    [Show full text]
  • Identification of a Novel Fused Gene Family Implicates Convergent
    Chen et al. BMC Genomics (2018) 19:306 https://doi.org/10.1186/s12864-018-4685-y RESEARCH ARTICLE Open Access Identification of a novel fused gene family implicates convergent evolution in eukaryotic calcium signaling Fei Chen1,2,3, Liangsheng Zhang1, Zhenguo Lin4 and Zong-Ming Max Cheng2,3* Abstract Background: Both calcium signals and protein phosphorylation responses are universal signals in eukaryotic cell signaling. Currently three pathways have been characterized in different eukaryotes converting the Ca2+ signals to the protein phosphorylation responses. All these pathways have based mostly on studies in plants and animals. Results: Based on the exploration of genomes and transcriptomes from all the six eukaryotic supergroups, we report here in Metakinetoplastina protists a novel gene family. This family, with a proposed name SCAMK,comprisesSnRK3 fused calmodulin-like III kinase genes and was likely evolved through the insertion of a calmodulin-like3 gene into an SnRK3 gene by unequal crossover of homologous chromosomes in meiosis cell. Its origin dated back to the time intersection at least 450 million-year-ago when Excavata parasites, Vertebrata hosts, and Insecta vectors evolved. We also analyzed SCAMK’s unique expression pattern and structure, and proposed it as one of the leading calcium signal conversion pathways in Excavata parasite. These characters made SCAMK gene as a potential drug target for treating human African trypanosomiasis. Conclusions: This report identified a novel gene fusion and dated its precise fusion time
    [Show full text]
  • The Planktonic Protist Interactome: Where Do We Stand After a Century of Research?
    bioRxiv preprint doi: https://doi.org/10.1101/587352; this version posted May 2, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Bjorbækmo et al., 23.03.2019 – preprint copy - BioRxiv The planktonic protist interactome: where do we stand after a century of research? Marit F. Markussen Bjorbækmo1*, Andreas Evenstad1* and Line Lieblein Røsæg1*, Anders K. Krabberød1**, and Ramiro Logares2,1** 1 University of Oslo, Department of Biosciences, Section for Genetics and Evolutionary Biology (Evogene), Blindernv. 31, N- 0316 Oslo, Norway 2 Institut de Ciències del Mar (CSIC), Passeig Marítim de la Barceloneta, 37-49, ES-08003, Barcelona, Catalonia, Spain * The three authors contributed equally ** Corresponding authors: Ramiro Logares: Institute of Marine Sciences (ICM-CSIC), Passeig Marítim de la Barceloneta 37-49, 08003, Barcelona, Catalonia, Spain. Phone: 34-93-2309500; Fax: 34-93-2309555. [email protected] Anders K. Krabberød: University of Oslo, Department of Biosciences, Section for Genetics and Evolutionary Biology (Evogene), Blindernv. 31, N-0316 Oslo, Norway. Phone +47 22845986, Fax: +47 22854726. [email protected] Abstract Microbial interactions are crucial for Earth ecosystem function, yet our knowledge about them is limited and has so far mainly existed as scattered records. Here, we have surveyed the literature involving planktonic protist interactions and gathered the information in a manually curated Protist Interaction DAtabase (PIDA). In total, we have registered ~2,500 ecological interactions from ~500 publications, spanning the last 150 years.
    [Show full text]
  • Rhizaria, Cercozoa)
    Protist, Vol. 166, 363–373, July 2015 http://www.elsevier.de/protis Published online date 28 May 2015 ORIGINAL PAPER Molecular Phylogeny of the Widely Distributed Marine Protists, Phaeodaria (Rhizaria, Cercozoa) a,1 a a b Yasuhide Nakamura , Ichiro Imai , Atsushi Yamaguchi , Akihiro Tuji , c d Fabrice Not , and Noritoshi Suzuki a Plankton Laboratory, Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041–8611, Japan b Department of Botany, National Museum of Nature and Science, Tsukuba 305–0005, Japan c CNRS, UMR 7144 & Université Pierre et Marie Curie, Station Biologique de Roscoff, Equipe EPPO - Evolution du Plancton et PaléoOcéans, Place Georges Teissier, 29682 Roscoff, France d Institute of Geology and Paleontology, Graduate School of Science, Tohoku University, Sendai 980–8578, Japan Submitted January 1, 2015; Accepted May 19, 2015 Monitoring Editor: David Moreira Phaeodarians are a group of widely distributed marine cercozoans. These plankton organisms can exhibit a large biomass in the environment and are supposed to play an important role in marine ecosystems and in material cycles in the ocean. Accurate knowledge of phaeodarian classification is thus necessary to better understand marine biology, however, phylogenetic information on Phaeodaria is limited. The present study analyzed 18S rDNA sequences encompassing all existing phaeodarian orders, to clarify their phylogenetic relationships and improve their taxonomic classification. The mono- phyly of Phaeodaria was confirmed and strongly supported by phylogenetic analysis with a larger data set than in previous studies. The phaeodarian clade contained 11 subclades which generally did not correspond to the families and orders of the current classification system. Two families (Challengeri- idae and Aulosphaeridae) and two orders (Phaeogromida and Phaeocalpida) are possibly polyphyletic or paraphyletic, and consequently the classification needs to be revised at both the family and order levels by integrative taxonomy approaches.
    [Show full text]
  • 33. Cretaceous and Paleogene Planktonic Foraminifera, Leg 27 of the Deep Sea Drilling Project V
    33. CRETACEOUS AND PALEOGENE PLANKTONIC FORAMINIFERA, LEG 27 OF THE DEEP SEA DRILLING PROJECT V. A. Krasheninnikov, Geological Institute of the Academy of Sciences, Moscow, USSR ABSTRACT Cretaceous and Cenozoic sediments, penetrated by Sites 259, 260, 261, and 263 in the eastern part of the Indian Ocean, are mainly brown zeolite clays and turbidites. Small quantities of calcareous clays and nanno ooze with planktonic foraminifera are intercalated with the clays and have Albian, upper Paleocene, and lower Eocene ages. The Albian sediments at Site 259 are characterized only by Hedbergella species (infracretacea, globigerinellinoides, planispira, amabilis, aff. delrioensis, aff. infracretacea). At Site 260 planktonic foraminifera are more diverse; in addition to the above-mentioned species there are other species of Hedbergella (trocoidea brittonensis) and representatives of Globigerinelloides (eaglefordensis, bentonensis, ultramicra, gyroidinaeformis, aff. maridalensis). Assemblages of planktonic foraminifera of the upper Paleocene (the Globorotalia velascoensis Zone) at Site 259 consist of comparatively rare species of Acarinina (acarinata, mckannai, primitival and Glpbigerina (chascanona, nana) combined with sporadic Globorotalia (imitata, aff. acuta). Sediments of the lower part of the lower Eocene at Site 259 are characterized by rare Acarinina (pseudotopilensis, soldadoensis, acarinata, aff. triplex) and casts of Globorotalia from the group of Globorotalia aequa— G. subbotinae—G. marginodentata. Turbidites contain rather frequently redeposited Cretaceous, Paleogene, and Neogene planktonic foraminifera. LOWER CRETACEOUS (ALBIAN) Lower Cretaceous sediments, Albian, with planktonic _____^^ ""W••l•i i•i•r;•i•: foraminifera have been identified in two regions of the Indian Ocean—the Perth Abyssal Plain in the south (Site 259) and the Gascoyne Abyssal Plain in the north (Site 260).
    [Show full text]
  • Evidence for Glycolytic Reactions in the Mitochondrion?
    Broad Distribution of TPI-GAPDH Fusion Proteins among Eukaryotes: Evidence for Glycolytic Reactions in the Mitochondrion? Takuro Nakayama1, Ken-ichiro Ishida2, John M. Archibald1* 1 Department of Biochemistry & Molecular Biology, Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity, Dalhousie University, Halifax, Nova Scotia, Canada, 2 Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan Abstract Glycolysis is a central metabolic pathway in eukaryotic and prokaryotic cells. In eukaryotes, the textbook view is that glycolysis occurs in the cytosol. However, fusion proteins comprised of two glycolytic enzymes, triosephosphate isomerase (TPI) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), were found in members of the stramenopiles (diatoms and oomycetes) and shown to possess amino-terminal mitochondrial targeting signals. Here we show that mitochondrial TPI- GAPDH fusion protein genes are widely spread across the known diversity of stramenopiles, including non-photosynthetic species (Bicosoeca sp. and Blastocystis hominis). We also show that TPI-GAPDH fusion genes exist in three cercozoan taxa (Paulinella chromatophora, Thaumatomastix sp. and Mataza hastifera) and an apusozoan protist, Thecamonas trahens. Interestingly, subcellular localization predictions for other glycolytic enzymes in stramenopiles and a cercozoan show that a significant fraction of the glycolytic enzymes in these species have mitochondrial-targeted isoforms. These results suggest that part
    [Show full text]
  • Protist Phylogeny and the High-Level Classification of Protozoa
    Europ. J. Protistol. 39, 338–348 (2003) © Urban & Fischer Verlag http://www.urbanfischer.de/journals/ejp Protist phylogeny and the high-level classification of Protozoa Thomas Cavalier-Smith Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK; E-mail: [email protected] Received 1 September 2003; 29 September 2003. Accepted: 29 September 2003 Protist large-scale phylogeny is briefly reviewed and a revised higher classification of the kingdom Pro- tozoa into 11 phyla presented. Complementary gene fusions reveal a fundamental bifurcation among eu- karyotes between two major clades: the ancestrally uniciliate (often unicentriolar) unikonts and the an- cestrally biciliate bikonts, which undergo ciliary transformation by converting a younger anterior cilium into a dissimilar older posterior cilium. Unikonts comprise the ancestrally unikont protozoan phylum Amoebozoa and the opisthokonts (kingdom Animalia, phylum Choanozoa, their sisters or ancestors; and kingdom Fungi). They share a derived triple-gene fusion, absent from bikonts. Bikonts contrastingly share a derived gene fusion between dihydrofolate reductase and thymidylate synthase and include plants and all other protists, comprising the protozoan infrakingdoms Rhizaria [phyla Cercozoa and Re- taria (Radiozoa, Foraminifera)] and Excavata (phyla Loukozoa, Metamonada, Euglenozoa, Percolozoa), plus the kingdom Plantae [Viridaeplantae, Rhodophyta (sisters); Glaucophyta], the chromalveolate clade, and the protozoan phylum Apusozoa (Thecomonadea, Diphylleida). Chromalveolates comprise kingdom Chromista (Cryptista, Heterokonta, Haptophyta) and the protozoan infrakingdom Alveolata [phyla Cilio- phora and Miozoa (= Protalveolata, Dinozoa, Apicomplexa)], which diverged from a common ancestor that enslaved a red alga and evolved novel plastid protein-targeting machinery via the host rough ER and the enslaved algal plasma membrane (periplastid membrane).
    [Show full text]
  • Extensive Molecular Tinkering in the Evolution of the Membrane Attachment Mode of the Rheb Gtpase
    www.nature.com/scientificreports OPEN Extensive molecular tinkering in the evolution of the membrane attachment mode of the Rheb Received: 14 December 2017 Accepted: 15 March 2018 GTPase Published: xx xx xxxx Kristína Záhonová1, Romana Petrželková1, Matus Valach 2, Euki Yazaki3, Denis V. Tikhonenkov4, Anzhelika Butenko1, Jan Janouškovec5, Štěpánka Hrdá6, Vladimír Klimeš1, Gertraud Burger 2, Yuji Inagaki7, Patrick J. Keeling8, Vladimír Hampl6, Pavel Flegontov1, Vyacheslav Yurchenko1 & Marek Eliáš1 Rheb is a conserved and widespread Ras-like GTPase involved in cell growth regulation mediated by the (m)TORC1 kinase complex and implicated in tumourigenesis in humans. Rheb function depends on its association with membranes via prenylated C-terminus, a mechanism shared with many other eukaryotic GTPases. Strikingly, our analysis of a phylogenetically rich sample of Rheb sequences revealed that in multiple lineages this canonical and ancestral membrane attachment mode has been variously altered. The modifcations include: (1) accretion to the N-terminus of two diferent phosphatidylinositol 3-phosphate-binding domains, PX in Cryptista (the fusion being the frst proposed synapomorphy of this clade), and FYVE in Euglenozoa and the related undescribed fagellate SRT308; (2) acquisition of lipidic modifcations of the N-terminal region, namely myristoylation and/ or S-palmitoylation in seven diferent protist lineages; (3) acquisition of S-palmitoylation in the hypervariable C-terminal region of Rheb in apusomonads, convergently to some other Ras family proteins; (4) replacement of the C-terminal prenylation motif with four transmembrane segments in a novel Rheb paralog in the SAR clade; (5) loss of an evident C-terminal membrane attachment mechanism in Tremellomycetes and some Rheb paralogs of Euglenozoa.
    [Show full text]
  • Radiozoa (Acantharia, Phaeodaria and Radiolaria) and Heliozoa
    MICC16 26/09/2005 12:21 PM Page 188 CHAPTER 16 Radiozoa (Acantharia, Phaeodaria and Radiolaria) and Heliozoa Cavalier-Smith (1987) created the phylum Radiozoa to Radiating outwards from the central capsule are the include the marine zooplankton Acantharia, Phaeodaria pseudopodia, either as thread-like filopodia or as and Radiolaria, united by the presence of a central axopodia, which have a central rod of fibres for rigid- capsule. Only the Radiolaria including the siliceous ity. The ectoplasm typically contains a zone of frothy, Polycystina (which includes the orders Spumellaria gelatinous bubbles, collectively termed the calymma and Nassellaria) and the mixed silica–organic matter and a swarm of yellow symbiotic algae called zooxan- Phaeodaria are preserved in the fossil record. The thellae. The calymma in some spumellarian Radiolaria Acantharia have a skeleton of strontium sulphate can be so extensive as to obscure the skeleton. (i.e. celestine SrSO4). The radiolarians range from the A mineralized skeleton is usually present within the Cambrian and have a virtually global, geographical cell and comprises, in the simplest forms, either radial distribution and a depth range from the photic zone or tangential elements, or both. The radial elements down to the abyssal plains. Radiolarians are most useful consist of loose spicules, external spines or internal for biostratigraphy of Mesozoic and Cenozoic deep sea bars. They may be hollow or solid and serve mainly to sediments and as palaeo-oceanographical indicators. support the axopodia. The tangential elements, where Heliozoa are free-floating protists with roughly present, generally form a porous lattice shell of very spherical shells and thread-like pseudopodia that variable morphology, such as spheres, spindles and extend radially over a delicate silica endoskeleton.
    [Show full text]
  • Phylogenetische Analyse Der 18S Rrna Identifiziert Den
    ZOBODAT - www.zobodat.at Zoologisch-Botanische Datenbank/Zoological-Botanical Database Digitale Literatur/Digital Literature Zeitschrift/Journal: Denisia Jahr/Year: 2004 Band/Volume: 0013 Autor(en)/Author(s): Wylezich Claudia, Radek Renate, Schlegel Martin Artikel/Article: Phylogenetische Analyse der 18S rRNA identifiziert den parasitschen Protisten Nephridiophaga blattellae (Nephridiophagidae) als Vertreter der Zygomycota (Fungi) 435-442 © Biologiezentrum Linz/Austria; download unter www.biologiezentrum.at Denisia 13 | 17.09.2004 | 435-442 Phylogenetische Analyse der 18S rRNA identifiziert den parasitischen Protisten Nephridiophaga blattet I ae (Nephridiophagidae) als Vertreter der Zygomycota (Fungi)1 C. WYLEZICH, R. RADEK £t M. SCHLEGEL Abstract: Phylogenetic analysis of 18S rRNA identifies the parasitic protist Nephridiophaga blattellae (Nephrid- iophagidae) as a member of fungi. — The taxonomic affiliation of the spore-forming, unicellular nephridiophagids that thrive in the Malpighian tubules of insects is still completely unresolved. Their morphological and ultrastruc- tural characters do not closely resemble any known taxon of spore-forming protists. Some authors classed them with the Haplosporidia but proof is poor; e.g. the typical haplosporosomes are missing in nephridiophagids. In the present examination, the 18S rRNA of Nephridiophaga blatiellae (from the German cockroach Blauella germanica) was ampli- fied and sequenced in order to reconstruct the phylogenetic relationships of that group. Results exclude a close rela- tion to haplosporidia. Data rather support their classification within the fungi. Morphological findings such as the presence of chitin also argue in favour of this hypothesis. According to our analysis the exact position of nephridio- phagids seems to be near to the Zygomycota, as it is also reported for microsporidia. Key words: Nephridiophagidae, phylogeny, Zygomycota, Microsporidia, 18S rRNA.
    [Show full text]