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Hiltunen Thorén M, Onuț-Brännström I, Alfjorden A, Pecková H, Swords F, Hooper C, Holzer AS, Bass D, Burki F. Comparative genomics of Ascetosporea gives new insight into the evolutionary basis for animal parasitism in Rhizaria. BMC Biol 2024; 22:103. [PMID: 38702750 PMCID: PMC11069148 DOI: 10.1186/s12915-024-01898-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 04/22/2024] [Indexed: 05/06/2024] Open
Abstract
BACKGROUND Ascetosporea (Endomyxa, Rhizaria) is a group of unicellular parasites infecting aquatic invertebrates. They are increasingly being recognized as widespread and important in marine environments, causing large annual losses in invertebrate aquaculture. Despite their importance, little molecular data of Ascetosporea exist, with only two genome assemblies published to date. Accordingly, the evolutionary origin of these parasites is unclear, including their phylogenetic position and the genomic adaptations that accompanied the transition from a free-living lifestyle to parasitism. Here, we sequenced and assembled three new ascetosporean genomes, as well as the genome of a closely related amphizoic species, to investigate the phylogeny, origin, and genomic adaptations to parasitism in Ascetosporea. RESULTS Using a phylogenomic approach, we confirm the monophyly of Ascetosporea and show that Paramyxida group with Mikrocytida, with Haplosporida being sister to both groups. We report that the genomes of these parasites are relatively small (12-36 Mb) and gene-sparse (~ 2300-5200 genes), while containing surprisingly high amounts of non-coding sequence (~ 70-90% of the genomes). Performing gene-tree aware ancestral reconstruction of gene families, we demonstrate extensive gene losses at the origin of parasitism in Ascetosporea, primarily of metabolic functions, and little gene gain except on terminal branches. Finally, we highlight some functional gene classes that have undergone expansions during evolution of the group. CONCLUSIONS We present important new genomic information from a lineage of enigmatic but important parasites of invertebrates and illuminate some of the genomic innovations accompanying the evolutionary transition to parasitism in this lineage. Our results and data provide a genetic basis for the development of control measures against these parasites.
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Affiliation(s)
- Markus Hiltunen Thorén
- Department of Organismal Biology, Uppsala University, Norbyv. 18D, Uppsala, SE-752 36, Sweden.
- Present Address: Department of Ecology, Environment and Plant Sciences, Stockholm University, Svante Arrhenius V. 20 A, Stockholm, SE-114 18, Sweden.
- Present Address: The Royal Swedish Academy of Sciences, Stockholm, SE-114 18, Sweden.
| | - Ioana Onuț-Brännström
- Present Address: Department of Ecology and Genetics, Uppsala University, Norbyv. 18D, Uppsala, SE-752 36, Sweden
- Present Address: Natural History Museum, Oslo University, Oslo, 0562, Norway
| | - Anders Alfjorden
- Department of Organismal Biology, Uppsala University, Norbyv. 18D, Uppsala, SE-752 36, Sweden
| | - Hana Pecková
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, 370 05, Czech Republic
| | - Fiona Swords
- Marine Institute, Rinville, Oranmore, H91R673, Ireland
| | - Chantelle Hooper
- Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset, DT4 8UB, UK
- Sustainable Aquaculture Futures, Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Astrid S Holzer
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice, 370 05, Czech Republic
- Division of Fish Health, University of Veterinary Medicine, Veterinärplatz 1, Vienna, 1210, Austria
| | - David Bass
- Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset, DT4 8UB, UK
- Sustainable Aquaculture Futures, Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Natural History Museum (NHM), Science, London, SW7 5BD, UK
| | - Fabien Burki
- Department of Organismal Biology, Uppsala University, Norbyv. 18D, Uppsala, SE-752 36, Sweden.
- Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
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2
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Grujčić V, Saarenpää S, Sundh J, Sennblad B, Norgren B, Latz M, Giacomello S, Foster RA, Andersson AF. Towards high-throughput parallel imaging and single-cell transcriptomics of microbial eukaryotic plankton. PLoS One 2024; 19:e0296672. [PMID: 38241213 PMCID: PMC10798536 DOI: 10.1371/journal.pone.0296672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 12/13/2023] [Indexed: 01/21/2024] Open
Abstract
Single-cell transcriptomics has the potential to provide novel insights into poorly studied microbial eukaryotes. Although several such technologies are available and benchmarked on mammalian cells, few have been tested on protists. Here, we applied a microarray single-cell sequencing (MASC-seq) technology, that generates microscope images of cells in parallel with capturing their transcriptomes, on three species representing important plankton groups with different cell structures; the ciliate Tetrahymena thermophila, the diatom Phaeodactylum tricornutum, and the dinoflagellate Heterocapsa sp. Both the cell fixation and permeabilization steps were adjusted. For the ciliate and dinoflagellate, the number of transcripts of microarray spots with single cells were significantly higher than for background spots, and the overall expression patterns were correlated with that of bulk RNA, while for the much smaller diatom cells, it was not possible to separate single-cell transcripts from background. The MASC-seq method holds promise for investigating "microbial dark matter", although further optimizations are necessary to increase the signal-to-noise ratio.
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Affiliation(s)
- Vesna Grujčić
- Science for Life Laboratory, Department of Gene Technology, KTH Royal Institute of Technology, Stockholm, Sweden
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Sami Saarenpää
- Science for Life Laboratory, Department of Gene Technology, KTH Royal Institute of Technology, Stockholm, Sweden
| | - John Sundh
- Science for Life Laboratory, Department of Biochemistry and Biophysics, National Bioinformatics Infrastructure Sweden, Stockholm University, Solna, Sweden
| | - Bengt Sennblad
- Science for Life Laboratory, Dept of Cell and Molecular Biology, National Bioinformatics Infrastructure Sweden, Uppsala University, Uppsala, Sweden
| | - Benjamin Norgren
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Meike Latz
- Science for Life Laboratory, Department of Gene Technology, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Stefania Giacomello
- Science for Life Laboratory, Department of Gene Technology, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Rachel A. Foster
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Anders F. Andersson
- Science for Life Laboratory, Department of Gene Technology, KTH Royal Institute of Technology, Stockholm, Sweden
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3
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Single-Cell Genomics Reveals the Divergent Mitochondrial Genomes of Retaria (Foraminifera and Radiolaria). mBio 2023; 14:e0030223. [PMID: 36939357 PMCID: PMC10127745 DOI: 10.1128/mbio.00302-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2023] Open
Abstract
Mitochondria originated from an ancient bacterial endosymbiont that underwent reductive evolution by gene loss and endosymbiont gene transfer to the nuclear genome. The diversity of mitochondrial genomes published to date has revealed that gene loss and transfer processes are ongoing in many lineages. Most well-studied eukaryotic lineages are represented in mitochondrial genome databases, except for the superphylum Retaria-the lineage comprising Foraminifera and Radiolaria. Using single-cell approaches, we determined two complete mitochondrial genomes of Foraminifera and two nearly complete mitochondrial genomes of radiolarians. We report the complete coding content of an additional 14 foram species. We show that foraminiferan and radiolarian mitochondrial genomes contain a nearly fully overlapping but reduced mitochondrial gene complement compared to other sequenced rhizarians. In contrast to animals and fungi, many protists encode a diverse set of proteins on their mitochondrial genomes, including several ribosomal genes; however, some aerobic eukaryotic lineages (euglenids, myzozoans, and chlamydomonas-like algae) have reduced mitochondrial gene content and lack all ribosomal genes. Similar to these reduced outliers, we show that retarian mitochondrial genomes lack ribosomal protein and tRNA genes, contain truncated and divergent small and large rRNA genes, and contain only 14 or 15 protein-coding genes, including nad1, -3, -4, -4L, -5, and -7, cob, cox1, -2, and -3, and atp1, -6, and -9, with forams and radiolarians additionally carrying nad2 and nad6, respectively. In radiolarian mitogenomes, a noncanonical genetic code was identified in which all three stop codons encode amino acids. Collectively, these results add to our understanding of mitochondrial genome evolution and fill in one of the last major gaps in mitochondrial sequence databases. IMPORTANCE We present the reduced mitochondrial genomes of Retaria, the rhizarian lineage comprising the phyla Foraminifera and Radiolaria. By applying single-cell genomic approaches, we found that foraminiferan and radiolarian mitochondrial genomes contain an overlapping but reduced mitochondrial gene complement compared to other sequenced rhizarians. An alternative genetic code was identified in radiolarian mitogenomes in which all three stop codons encode amino acids. Collectively, these results shed light on the divergent nature of the mitochondrial genomes from an ecologically important group, warranting further questions into the biological underpinnings of gene content variability and genetic code variation between mitochondrial genomes.
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Sierra R, Mauffrey F, Cruz J, Holzmann M, Gooday AJ, Maurer-Alcalá X, Thakur R, Greco M, Weiner AKM, Katz LA, Pawlowski J. Taxon-rich transcriptomics supports higher-level phylogeny and major evolutionary trends in Foraminifera. Mol Phylogenet Evol 2022; 174:107546. [PMID: 35690380 DOI: 10.1016/j.ympev.2022.107546] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 05/10/2022] [Accepted: 05/18/2022] [Indexed: 10/18/2022]
Abstract
Foraminifera, classified in the supergroup Rhizaria, are a common and highly diverse group of mainly marine protists. Despite their evolutionary and ecological importance, only limited genomic data (one partial genome and nine transcriptomic datasets) have been published for this group. Foraminiferal molecular phylogeny is largely based on 18S rRNA gene sequence analysis. However, due to highly variable evolutionary rates of substitution in ribosomal genes plus the existence of intragenomic variation at this locus, the relationships between and within foraminiferal classes remain uncertain. We analyze transcriptomic data from 28 species, adding 19 new species to the previously published dataset, including members of the strongly under-represented class Monothalamea. A phylogenomic reconstruction of Rhizaria, rooted with alveolates and stramenopiles, based on 199 genes and 68 species supports the monophyly of Foraminifera and their sister relationship to Polycystinea. The phylogenomic tree of Foraminifera is very similar to the 18S rRNA tree, with the paraphyletic single-chambered monothalamids giving rise to the multi-chambered Tubothalamea and Globothalamea. Within the Monothalamea, our analyses confirm the monophyly of the giant, deep-sea xenophyophores that branch within clade C and indicate the basal position of monothalamous clades D and E. The multi-chambered Globothalamea are monophyletic and comprise the paraphyletic Textulariida and monophyletic Rotaliida. Our phylogenomic analyses support major evolutionary trends of Foraminifera revealed by ribosomal phylogenies and reinforce their current higher-level classification.
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Affiliation(s)
- Roberto Sierra
- Department of Genetics and Evolution, University of Geneva, 1211 Geneva, Switzerland.
| | - Florian Mauffrey
- Department of Genetics and Evolution, University of Geneva, 1211 Geneva, Switzerland
| | - Joana Cruz
- Department of Genetics and Evolution, University of Geneva, 1211 Geneva, Switzerland
| | - Maria Holzmann
- Department of Genetics and Evolution, University of Geneva, 1211 Geneva, Switzerland
| | - Andrew J Gooday
- National Oceanography Centre, European Way, Southampton SO14 3ZH, UK; Life Sciences Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - Xyrus Maurer-Alcalá
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, NY, USA
| | - Rabindra Thakur
- Department of Biological Sciences, Smith College, Northampton, MA 01063, USA; University of Massachusetts Amherst, Program in Organismic and Evolutionary Biology, Amherst, MA, USA
| | - Mattia Greco
- Department of Biological Sciences, Smith College, Northampton, MA 01063, USA; Institute of Oceanology, Polish Academy of Sciences, 81-712 Sopot, Poland
| | - Agnes K M Weiner
- Department of Biological Sciences, Smith College, Northampton, MA 01063, USA; NORCE Climate and Environment, NORCE Norwegian Research Centre AS, Jahnebakken 5, 5007 Bergen, Norway
| | - Laura A Katz
- Department of Biological Sciences, Smith College, Northampton, MA 01063, USA; University of Massachusetts Amherst, Program in Organismic and Evolutionary Biology, Amherst, MA, USA
| | - Jan Pawlowski
- Department of Genetics and Evolution, University of Geneva, 1211 Geneva, Switzerland; Institute of Oceanology, Polish Academy of Sciences, 81-712 Sopot, Poland; ID-Gene Ecodiagnostics, Chemin du Pont-du-Centenaire 109, CH-1228 Plan-les-Ouates, Switzerland
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5
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Goleń J, Tyszka J, Godos K, Janse M. A Model of F-actin Organization in Granuloreticulopodia in Foraminifera: Morphogenetic and Evolutionary Implications from Novel Fluorescent and Polarised Light Observations. Protist 2022; 173:125886. [DOI: 10.1016/j.protis.2022.125886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 04/22/2022] [Accepted: 05/08/2022] [Indexed: 11/29/2022]
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6
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Tria FDK, Brueckner J, Skejo J, Xavier JC, Kapust N, Knopp M, Wimmer JLE, Nagies FSP, Zimorski V, Gould SB, Garg SG, Martin WF. Gene Duplications Trace Mitochondria to the Onset of Eukaryote Complexity. Genome Biol Evol 2021; 13:evab055. [PMID: 33739376 PMCID: PMC8175051 DOI: 10.1093/gbe/evab055] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/14/2021] [Indexed: 12/15/2022] Open
Abstract
The last eukaryote common ancestor (LECA) possessed mitochondria and all key traits that make eukaryotic cells more complex than their prokaryotic ancestors, yet the timing of mitochondrial acquisition and the role of mitochondria in the origin of eukaryote complexity remain debated. Here, we report evidence from gene duplications in LECA indicating an early origin of mitochondria. Among 163,545 duplications in 24,571 gene trees spanning 150 sequenced eukaryotic genomes, we identify 713 gene duplication events that occurred in LECA. LECA's bacterial-derived genes include numerous mitochondrial functions and were duplicated significantly more often than archaeal-derived and eukaryote-specific genes. The surplus of bacterial-derived duplications in LECA most likely reflects the serial copying of genes from the mitochondrial endosymbiont to the archaeal host's chromosomes. Clustering, phylogenies and likelihood ratio tests for 22.4 million genes from 5,655 prokaryotic and 150 eukaryotic genomes reveal no evidence for lineage-specific gene acquisitions in eukaryotes, except from the plastid in the plant lineage. That finding, and the functions of bacterial genes duplicated in LECA, suggests that the bacterial genes in eukaryotes are acquisitions from the mitochondrion, followed by vertical gene evolution and differential loss across eukaryotic lineages, flanked by concomitant lateral gene transfer among prokaryotes. Overall, the data indicate that recurrent gene transfer via the copying of genes from a resident mitochondrial endosymbiont to archaeal host chromosomes preceded the onset of eukaryotic cellular complexity, favoring mitochondria-early over mitochondria-late hypotheses for eukaryote origin.
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Affiliation(s)
- Fernando D K Tria
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Germany
| | - Julia Brueckner
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Germany
| | - Josip Skejo
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Germany
- Faculty of Science, University of Zagreb, Croatia
| | - Joana C Xavier
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Germany
| | - Nils Kapust
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Germany
| | - Michael Knopp
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Germany
| | - Jessica L E Wimmer
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Germany
| | - Falk S P Nagies
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Germany
| | - Verena Zimorski
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Germany
| | - Sven B Gould
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Germany
| | - Sriram G Garg
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Germany
| | - William F Martin
- Institute for Molecular Evolution, Heinrich Heine University Düsseldorf, Germany
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7
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Lax G, Kolisko M, Eglit Y, Lee WJ, Yubuki N, Karnkowska A, Leander BS, Burger G, Keeling PJ, Simpson AGB. Multigene phylogenetics of euglenids based on single-cell transcriptomics of diverse phagotrophs. Mol Phylogenet Evol 2021; 159:107088. [PMID: 33545276 DOI: 10.1016/j.ympev.2021.107088] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 01/24/2021] [Accepted: 01/26/2021] [Indexed: 12/22/2022]
Abstract
Euglenids are a well-known group of single-celled eukaryotes, with phototrophic, osmotrophic and phagotrophic members. Phagotrophs represent most of the phylogenetic diversity of euglenids, and gave rise to the phototrophs and osmotrophs, but their evolutionary relationships are poorly understood. Symbiontids, in contrast, are anaerobes that are alternatively inferred to be derived euglenids, or a separate euglenozoan group. Most phylogenetic studies of euglenids have examined the SSU rDNA only, which is often highly divergent. Also, many phagotrophic euglenids (and symbiontids) are uncultured, restricting collection of other molecular data. We generated transcriptome data for 28 taxa, mostly using a single-cell approach, and conducted the first multigene phylogenetic analyses of euglenids to include phagotrophs and symbiontids. Euglenids are recovered as monophyletic, with symbiontids forming an independent branch within Euglenozoa. Spirocuta, the clade of flexible euglenids that contains both the phototrophs (Euglenophyceae) and osmotrophs (Aphagea), is robustly resolved, with the ploeotid Olkasia as its sister group, forming the new taxon Olkaspira. Ploeotids are paraphyletic, although Ploeotiidae (represented by Ploeotia spp.), Lentomonas, and Keelungia form a robust clade (new taxon Alistosa). Petalomonadida branches robustly as sister to other euglenids in outgroup-rooted analyses. Within Spirocuta, Euglenophyceae is a robust clade that includes Rapaza, and Anisonemia is a well-supported monophyletic group containing Anisonemidae (Anisonema and Dinema spp.), 'Heteronema II' (represented by H. vittatum), and a clade of Neometanema plus Aphagea. Among 'peranemid' phagotrophs, Chasmostoma branches with included Urceolus, and Peranema with the undescribed 'Jenningsia II', while other relationships are weakly supported and consequently the closest sister group to Euglenophyceae remains unresolved. Our results are inconsistent with recent inferences that Entosiphon is the evolutionarily pivotal sister either to other euglenids, or to Spirocuta. At least three transitions between posterior and anterior flagellar gliding occurred in euglenids, with the phylogenetic positions and directions of those transitions remaining ambiguous.
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Affiliation(s)
- G Lax
- Department of Biology, and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Canada; Department of Botany, University of British Columbia, Vancouver, Canada(1)
| | - M Kolisko
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Y Eglit
- Department of Biology, and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Canada
| | - W J Lee
- Department of Environment and Energy Engineering, Kyungnam University, Changwon, Republic of Korea
| | - N Yubuki
- Unité d'Ecologie Systématique et Evolution, CNRS, Université Paris-Saclay, Orsay, France; Department of Zoology, University of British Columbia, Vancouver, Canada
| | - A Karnkowska
- Institute of Evolutionary Biology, Faculty of Biology, University of Warsaw, Poland
| | - B S Leander
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - G Burger
- Robert-Cedergren Centre for Bioinformatics and Genomics, Biochemistry Department, Université de Montréal, Montréal, Canada
| | - P J Keeling
- Department of Botany, University of British Columbia, Vancouver, Canada(1)
| | - A G B Simpson
- Department of Biology, and Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, Canada.
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8
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Hanschen ER, Hovde BT, Starkenburg SR. An evaluation of methodology to determine algal genome completeness. ALGAL RES 2020. [DOI: 10.1016/j.algal.2020.102019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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10
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The architecture of the Plasmodiophora brassicae nuclear and mitochondrial genomes. Sci Rep 2019; 9:15753. [PMID: 31673019 PMCID: PMC6823432 DOI: 10.1038/s41598-019-52274-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 10/15/2019] [Indexed: 11/09/2022] Open
Abstract
Plasmodiophora brassicae is a soil-borne pathogen that attacks roots of cruciferous plants causing clubroot disease. The pathogen belongs to the Plasmodiophorida order in Phytomyxea. Here we used long-read SMRT technology to clarify the P. brassicae e3 genomic constituents along with comparative and phylogenetic analyses. Twenty contigs representing the nuclear genome and one mitochondrial (mt) contig were generated, together comprising 25.1 Mbp. Thirteen of the 20 nuclear contigs represented chromosomes from telomere to telomere characterized by [TTTTAGGG] sequences. Seven active gene candidates encoding synaptonemal complex-associated and meiotic-related protein homologs were identified, a finding that argues for possible genetic recombination events. The circular mt genome is large (114,663 bp), gene dense and intron rich. It shares high synteny with the mt genome of Spongospora subterranea, except in a unique 12 kb region delimited by shifts in GC content and containing tandem minisatellite- and microsatellite repeats with partially palindromic sequences. De novo annotation identified 32 protein-coding genes, 28 structural RNA genes and 19 ORFs. ORFs predicted in the repeat-rich region showed similarities to diverse organisms suggesting possible evolutionary connections. The data generated here form a refined platform for the next step involving functional analysis, all to clarify the complex biology of P. brassicae.
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11
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Burki F, Roger AJ, Brown MW, Simpson AGB. The New Tree of Eukaryotes. Trends Ecol Evol 2019; 35:43-55. [PMID: 31606140 DOI: 10.1016/j.tree.2019.08.008] [Citation(s) in RCA: 389] [Impact Index Per Article: 77.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/15/2019] [Accepted: 08/15/2019] [Indexed: 01/01/2023]
Abstract
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. The evidence that supports the tree has transitioned from a synthesis of molecular phylogenetics and biological characters to purely molecular phylogenetics. Most current supergroups lack defining morphological or cell-biological characteristics, making the supergroup label even more arbitrary than before. Going forward, the combination of traditional culturing with maturing culture-free approaches and phylogenomics should accelerate the process of completing and resolving the eToL at its deepest levels.
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Affiliation(s)
- Fabien Burki
- Department of Organismal Biology, Program in Systematic Biology, Uppsala University, Uppsala, Sweden; Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
| | - Andrew J Roger
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, Canada; Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, NS, Canada
| | - Matthew W Brown
- Department of Biological Sciences, Mississippi State University, Mississippi State, MS, USA; Institute for Genomics, Biocomputing, and Biotechnology, Mississippi State University, Mississippi State, MS, USA
| | - Alastair G B Simpson
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Dalhousie University, Halifax, NS, Canada; Department of Biology, Dalhousie University, Halifax, NS, Canada.
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12
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Tyml T, Date SV, Woyke T. A single-cell genome perspective on studying intracellular associations in unicellular eukaryotes. Philos Trans R Soc Lond B Biol Sci 2019; 374:20190082. [PMID: 31587647 PMCID: PMC6792452 DOI: 10.1098/rstb.2019.0082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Single-cell genomics (SCG) methods provide a unique opportunity to analyse whole genome information at the resolution of an individual cell. While SCG has been extensively used to investigate bacterial and archaeal genomes, the technique has been rarely used to access the genetic makeup of uncultivated microbial eukaryotes. In this regard, the use of SCG can provide a wealth of information; not only do the methods allow exploration of the genome, they can also help elucidate the relationship between the cell and intracellular entities extant in nearly all eukaryotes. SCG enables the study of total eukaryotic cellular DNA, which in turn allows us to better understand the evolutionary history and diversity of life, and the physiological interactions that define complex organisms. This article is part of a discussion meeting issue ‘Single cell ecology’.
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Affiliation(s)
- Tomáš Tyml
- U.S. Department of Energy, Joint Genome Institute, Walnut Creek, CA, USA.,Global Viral, San Francisco, CA, USA
| | | | - Tanja Woyke
- U.S. Department of Energy, Joint Genome Institute, Walnut Creek, CA, USA
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13
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Quartet-Based Computations of Internode Certainty Provide Robust Measures of Phylogenetic Incongruence. Syst Biol 2019; 69:308-324. [DOI: 10.1093/sysbio/syz058] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 08/26/2019] [Indexed: 11/14/2022] Open
Abstract
Abstract
Incongruence, or topological conflict, is prevalent in genome-scale data sets. Internode certainty (IC) and related measures were recently introduced to explicitly quantify the level of incongruence of a given internal branch among a set of phylogenetic trees and complement regular branch support measures (e.g., bootstrap, posterior probability) that instead assess the statistical confidence of inference. Since most phylogenomic studies contain data partitions (e.g., genes) with missing taxa and IC scores stem from the frequencies of bipartitions (or splits) on a set of trees, IC score calculation typically requires adjusting the frequencies of bipartitions from these partial gene trees. However, when the proportion of missing taxa is high, the scores yielded by current approaches that adjust bipartition frequencies in partial gene trees differ substantially from each other and tend to be overestimates. To overcome these issues, we developed three new IC measures based on the frequencies of quartets, which naturally apply to both complete and partial trees. Comparison of our new quartet-based measures to previous bipartition-based measures on simulated data shows that: (1) on complete data sets, both quartet-based and bipartition-based measures yield very similar IC scores; (2) IC scores of quartet-based measures on a given data set with and without missing taxa are more similar than the scores of bipartition-based measures; and (3) quartet-based measures are more robust to the absence of phylogenetic signal and errors in phylogenetic inference than bipartition-based measures. Additionally, the analysis of an empirical mammalian phylogenomic data set using our quartet-based measures reveals the presence of substantial levels of incongruence for numerous internal branches. An efficient open-source implementation of these quartet-based measures is freely available in the program QuartetScores (https://github.com/lutteropp/QuartetScores).
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Abstract
Over 100 whole-genome sequences from algae are published or soon to be published. The rapidly increasing availability of these fundamental resources is changing how we understand one of the most diverse, complex, and understudied groups of photosynthetic eukaryotes. Genome sequences provide a window into the functional potential of individual algae, with phylogenomics and functional genomics as tools for contextualizing and transferring knowledge from reference organisms into less well-characterized systems. Remarkably, over half of the proteins encoded by algal genomes are of unknown function, highlighting the volume of functional capabilities yet to be discovered. In this review, we provide an overview of publicly available algal genomes, their associated protein inventories, and their quality, with a summary of the statuses of protein function understanding and predictions.
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Affiliation(s)
| | - Sabeeha S Merchant
- Departments of Plant and Microbial Biology and Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
- Institute for Genomics and Proteomics, University of California, Los Angeles, California 90095, USA
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15
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Laumer CE. Inferring Ancient Relationships with Genomic Data: A Commentary on Current Practices. Integr Comp Biol 2019; 58:623-639. [PMID: 29982611 DOI: 10.1093/icb/icy075] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Contemporary phylogeneticists enjoy an embarrassment of riches, not only in the volumes of data now available, but also in the diversity of bioinformatic tools for handling these data. Here, I discuss a subset of these tools I consider well-suited to the task of inferring ancient relationships with coding sequence data in particular, encompassing data generation, orthology assignment, alignment and gene tree inference, supermatrix construction, and analysis under the best-fitting models applicable to large-scale datasets. Throughout, I compare and critique methods, considering both their theoretical principles and the details of their implementation, and offering practical tips on usage where appropriate. I also entertain different motivations for analyzing what are almost always originally DNA sequence data as codons, amino acids, and higher-order recodings. Although presented in a linear order, I see value in using the diversity of tools available to us to assess the sensitivity of clades of biological interest to different gene and taxon sets and analytical modes, which can be an indication of the presence of systematic error, of which a few forms remain poorly controlled by even the best available inference methods.
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Affiliation(s)
- Christopher E Laumer
- EMBL-European Bioinformatics Institute, Wellcome Trust Genome Campus, EBML-EBI South Building, Hinxton CB10 1SD, UK
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16
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Lahr DJG, Kosakyan A, Lara E, Mitchell EAD, Morais L, Porfirio-Sousa AL, Ribeiro GM, Tice AK, Pánek T, Kang S, Brown MW. Phylogenomics and Morphological Reconstruction of Arcellinida Testate Amoebae Highlight Diversity of Microbial Eukaryotes in the Neoproterozoic. Curr Biol 2019; 29:991-1001.e3. [PMID: 30827918 DOI: 10.1016/j.cub.2019.01.078] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 10/26/2018] [Accepted: 01/30/2019] [Indexed: 11/26/2022]
Abstract
Life was microbial for the majority of Earth's history, but as very few microbial lineages leave a fossil record, the Precambrian evolution of life remains shrouded in mystery. Shelled (testate) amoebae stand out as an exception with rich documented diversity in the Neoproterozoic as vase-shaped microfossils (VSMs). While there is general consensus that most of these can be attributed to the Arcellinida lineage in Amoebozoa, it is still unclear whether they can be used as key fossils for interpretation of early eukaryotic evolution. Here, we present a well-resolved phylogenomic reconstruction based on 250 genes, obtained using single-cell transcriptomic techniques from a representative selection of 19 Arcellinid testate amoeba taxa. The robust phylogenetic framework enables deeper interpretations of evolution in this lineage and demanded an updated classification of the group. Additionally, we performed reconstruction of ancestral morphologies, yielding hypothetical ancestors remarkably similar to existing Neoproterozoic VSMs. We demonstrate that major lineages of testate amoebae were already diversified before the Sturtian glaciation (720 mya), supporting the hypothesis that massive eukaryotic diversification took place in the early Neoproterozoic and congruent with the interpretation that VSM are arcellinid testate amoebae.
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Affiliation(s)
- Daniel J G Lahr
- Department of Zoology, Institute of Biosciences, University of São Paulo, Brazil.
| | - Anush Kosakyan
- Department of Zoology, Institute of Biosciences, University of São Paulo, Brazil; Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Branišovská 1160/31, 37005, České Budějovice, Czech Republic
| | - Enrique Lara
- Real Jardín Botánico, CSIC, Plaza Murillo 2, ES 28014 Madrid, Spain; Laboratory of Soil Biodiversity, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
| | - Edward A D Mitchell
- Laboratory of Soil Biodiversity, University of Neuchâtel, Rue Emile-Argand 11, 2000 Neuchâtel, Switzerland; Botanical Garden of Neuchâtel, Pertuis-du-Sault 58, 2000 Neuchâtel, Switzerland
| | - Luana Morais
- Department of Geophysics, Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, Brazil
| | | | - Giulia M Ribeiro
- Department of Zoology, Institute of Biosciences, University of São Paulo, Brazil
| | - Alexander K Tice
- Department of Biological Sciences, Mississippi State University, Starkville, MS, USA; Institute for Genomics, Biocomputing and Biotechnology, Mississippi State University, Starkville, MS, USA
| | - Tomáš Pánek
- Department of Biological Sciences, Mississippi State University, Starkville, MS, USA; Department of Biology and Ecology, Faculty of Science, University of Ostrava, Czech Republic
| | - Seungho Kang
- Department of Biological Sciences, Mississippi State University, Starkville, MS, USA; Institute for Genomics, Biocomputing and Biotechnology, Mississippi State University, Starkville, MS, USA
| | - Matthew W Brown
- Department of Biological Sciences, Mississippi State University, Starkville, MS, USA; Institute for Genomics, Biocomputing and Biotechnology, Mississippi State University, Starkville, MS, USA.
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17
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Irwin NA, Tikhonenkov DV, Hehenberger E, Mylnikov AP, Burki F, Keeling PJ. Phylogenomics supports the monophyly of the Cercozoa. Mol Phylogenet Evol 2019; 130:416-423. [DOI: 10.1016/j.ympev.2018.09.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 09/06/2018] [Indexed: 01/09/2023]
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18
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Hemimastigophora is a novel supra-kingdom-level lineage of eukaryotes. Nature 2018; 564:410-414. [PMID: 30429611 DOI: 10.1038/s41586-018-0708-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 09/21/2018] [Indexed: 12/11/2022]
Abstract
Almost all eukaryote life forms have now been placed within one of five to eight supra-kingdom-level groups using molecular phylogenetics1-4. The 'phylum' Hemimastigophora is probably the most distinctive morphologically defined lineage that still awaits such a phylogenetic assignment. First observed in the nineteenth century, hemimastigotes are free-living predatory protists with two rows of flagella and a unique cell architecture5-7; to our knowledge, no molecular sequence data or cultures are currently available for this group. Here we report phylogenomic analyses based on high-coverage, cultivation-independent transcriptomics that place Hemimastigophora outside of all established eukaryote supergroups. They instead comprise an independent supra-kingdom-level lineage that most likely forms a sister clade to the 'Diaphoretickes' half of eukaryote diversity (that is, the 'stramenopiles, alveolates and Rhizaria' supergroup (Sar), Archaeplastida and Cryptista, as well as other major groups). The previous ranking of Hemimastigophora as a phylum understates the evolutionary distinctiveness of this group, which has considerable importance for investigations into the deep-level evolutionary history of eukaryotic life-ranging from understanding the origins of fundamental cell systems to placing the root of the tree. We have also established the first culture of a hemimastigote (Hemimastix kukwesjijk sp. nov.), which will facilitate future genomic and cell-biological investigations into eukaryote evolution and the last eukaryotic common ancestor.
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19
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Cavalier-Smith T, Chao EE, Lewis R. Multigene phylogeny and cell evolution of chromist infrakingdom Rhizaria: contrasting cell organisation of sister phyla Cercozoa and Retaria. PROTOPLASMA 2018; 255:1517-1574. [PMID: 29666938 PMCID: PMC6133090 DOI: 10.1007/s00709-018-1241-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 03/12/2018] [Indexed: 05/18/2023]
Abstract
Infrakingdom Rhizaria is one of four major subgroups with distinct cell body plans that comprise eukaryotic kingdom Chromista. Unlike other chromists, Rhizaria are mostly heterotrophic flagellates, amoebae or amoeboflagellates, commonly with reticulose (net-like) or filose (thread-like) feeding pseudopodia; uniquely for eukaryotes, cilia have proximal ciliary transition-zone hub-lattices. They comprise predominantly flagellate phylum Cercozoa and reticulopodial phylum Retaria, whose exact phylogenetic relationship has been uncertain. Given even less clear relationships amongst cercozoan classes, we sequenced partial transcriptomes of seven Cercozoa representing five classes and endomyxan retarian Filoreta marina to establish 187-gene multiprotein phylogenies. Ectoreta (retarian infraphyla Foraminifera, Radiozoa) branch within classical Cercozoa as sister to reticulose Endomyxa. This supports recent transfer of subphylum Endomyxa from Cercozoa to Retaria alongside subphylum Ectoreta which embraces classical retarians where capsules or tests subdivide cells into organelle-containing endoplasm and anastomosing pseudopodial net-like ectoplasm. Cercozoa are more homogeneously filose, often with filose pseudopodia and/or posterior ciliary gliding motility: zooflagellate Helkesimastix and amoeboid Guttulinopsis form a strongly supported clade, order Helkesida. Cercomonads are polyphyletic (Cercomonadida sister to glissomonads; Paracercomonadida deeper). Thecofilosea are a clade, whereas Imbricatea may not be; Sarcomonadea may be paraphyletic. Helkesea and Metromonadea are successively deeper outgroups within cercozoan subphylum Monadofilosa; subphylum Reticulofilosa (paraphyletic on site-heterogeneous trees) branches earliest, Granofilosea before Chlorarachnea. Our multiprotein trees confirm that Rhizaria are sisters of infrakingdom Halvaria (Alveolata, Heterokonta) within chromist subkingdom Harosa (= SAR); they further support holophyly of chromist subkingdom Hacrobia, and are consistent with holophyly of Chromista as sister of kingdom Plantae. Site-heterogeneous rDNA trees group Kraken with environmental DNA clade 'eSarcomonad', not Paracercomonadida. Ectoretan fossil dates evidence ultrarapid episodic stem sequence evolution. We discuss early rhizarian cell evolution and multigene tree coevolutionary patterns, gene-paralogue evidence for chromist monophyly, and integrate this with fossil evidence for the age of Rhizaria and eukaryote cells, and revise rhizarian classification.
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Affiliation(s)
| | - Ema E Chao
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - Rhodri Lewis
- Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
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20
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Bass D, Tikhonenkov DV, Foster R, Dyal P, Janouškovec J, Keeling PJ, Gardner M, Neuhauser S, Hartikainen H, Mylnikov AP, Berney C. Rhizarian 'Novel Clade 10' Revealed as Abundant and Diverse Planktonic and Terrestrial Flagellates, including Aquavolon n. gen. J Eukaryot Microbiol 2018; 65:828-842. [PMID: 29658156 PMCID: PMC6282753 DOI: 10.1111/jeu.12524] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 03/19/2018] [Accepted: 03/28/2018] [Indexed: 01/03/2023]
Abstract
Rhizarian ‘Novel Clade 10’ (NC10) is frequently detected by 18S rRNA gene sequencing studies in freshwater planktonic samples. We describe a new genus and two species of eukaryovorous biflagellate protists, Aquavolon hoantrani n. gen. n. sp. and A. dientrani n. gen. n. sp., which represent the first morphologically characterized members of NC10, here named Aquavolonida ord. nov. The slightly metabolic cells possess naked heterodynamic flagella, whose kinetosomes lie at a right angle to each other and are connected by at least one fibril. Unlike their closest known relative Tremula longifila, they rotate around their longitudinal axis when swimming and only very rarely glide on surfaces. Screening of a wide range of environmental DNA extractions with lineage‐specific PCR primers reveals that Aquavolonida consists of a large radiation of protists, which are most diversified in freshwater planktonic habitats and as yet undetected in marine environments. Earlier‐branching lineages in Aquavolonida include less frequently detected organisms from soils and freshwater sediments. The 18S rRNA gene phylogeny suggests that Aquavolonida forms a common evolutionary lineage with tremulids and uncharacterized ‘Novel Clade 12’, which likely represents one of the deepest lineages in the Rhizaria, separate from Cercozoa (Filosa), Endomyxa, and Retaria.
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Affiliation(s)
- David Bass
- Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK.,Centre for Environment, Fisheries and Aquaculture Science (Cefas), Barrack Road, The Nothe, Weymouth, DT4 8UB, UK
| | - Denis Victorovich Tikhonenkov
- Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, 152742, Russia.,Botany Department, University of British Columbia, Vancouver, BC, V6T1Z4, Canada
| | - Rachel Foster
- Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK
| | - Patricia Dyal
- Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK
| | - Jan Janouškovec
- Botany Department, University of British Columbia, Vancouver, BC, V6T1Z4, Canada.,Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK
| | - Patrick J Keeling
- Botany Department, University of British Columbia, Vancouver, BC, V6T1Z4, Canada
| | - Michelle Gardner
- Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK
| | - Sigrid Neuhauser
- Institute of Microbiology, University of Innsbruck, Technikerstraße 25, Innsbruck, 6020, Austria
| | - Hanna Hartikainen
- Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK
| | - Alexandre P Mylnikov
- Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Borok, 152742, Russia
| | - Cédric Berney
- Department of Life Sciences, The Natural History Museum, Cromwell Road, London, SW7 5BD, UK
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21
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Schaap P, Schilde C. Encystation: the most prevalent and underinvestigated differentiation pathway of eukaryotes. MICROBIOLOGY-SGM 2018; 164:727-739. [PMID: 29620506 DOI: 10.1099/mic.0.000653] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Not long ago, protists were considered one of four eukaryote kingdoms, but recent gene-based phylogenies show that they contribute to all nine eukaryote subdomains. The former kingdoms of animals, plants and fungi are now relegated to lower ranks within subdomains. Most unicellular protists respond to adverse conditions by differentiating into dormant walled cysts. As cysts, they survive long periods of starvation, drought and other environmental threats, only to re-emerge when conditions improve. For protists pathogens, the resilience of their cysts can prevent successful treatment or eradication of the disease. In this context, effort has been directed towards understanding the molecular mechanisms that control encystation. We here firstly summarize the prevalence of encystation across protists and next focus on Amoebozoa, where most of the health-related issues occur. We review current data on processes and genes involved in encystation of the obligate parasite Entamoeba histolytica and the opportunistic pathogen Acanthamoeba. We show how the cAMP-mediated signalling pathway that controls spore and stalk cell encapsulation in Dictyostelium fruiting bodies could be retraced to a stress-induced pathway controlling encystation in solitary Amoebozoa. We highlight the conservation and prevalence of cAMP signalling genes in Amoebozoan genomes and the suprisingly large and varied repertoire of proteins for sensing and processing environmental signals in individual species.
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Affiliation(s)
- Pauline Schaap
- School of Life Sciences, University of Dundee, Dundee DD15EH, UK
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22
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Backman L. Alpha-actinin of the chlorarchiniophyte Bigelowiella natans. PeerJ 2018; 6:e4288. [PMID: 29372122 PMCID: PMC5775757 DOI: 10.7717/peerj.4288] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 01/03/2018] [Indexed: 12/29/2022] Open
Abstract
The genome of the chlorarchiniophyte Bigelowiella natans codes for a protein annotated as an α-actinin-like protein. Analysis of the primary sequence indicate that this protein has the same domain structure as other α-actinins, a N-terminal actin-binding domain and a C-terminal calmodulin-like domain. These two domains are connected by a short rod domain, albeit long enough to form a single spectrin repeat. To analyse the functional properties of this protein, the full-length protein as well as the separate domains were cloned and isolated. Characerisation showed that the protein is capable of cross-linking actin filaments into dense bundles, probably due to dimer formation. Similar to human α-actinin, calcium-binding occurs to the most N-terminal EF-hand motif in the calmodulin-like C-terminal domain. The results indicate that this Bigelowiella protein is a proper α-actinin, with all common characteristics of a typical α-actinin.
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Affiliation(s)
- Lars Backman
- Department of Chemistry, Umeå University, Umeå, Sweden
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23
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The immunophilin repertoire of Plasmodiophora brassicae and functional analysis of PbCYP3 cyclophilin. Mol Genet Genomics 2017; 293:381-390. [PMID: 29128880 PMCID: PMC5854754 DOI: 10.1007/s00438-017-1395-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 11/06/2017] [Indexed: 11/05/2022]
Abstract
Plasmodiophora brassicae is a soil-borne pathogen that belongs to Rhizaria, an almost unexplored eukaryotic organism group. This pathogen requires a living host for growth and multiplication, which makes molecular analysis further complicated. To broaden our understanding of a plasmodiophorid such as P. brassicae, we here chose to study immunophilins, a group of proteins known to have various cellular functions, including involvement in plant defense and pathogen virulence. Searches in the P. brassicae genome resulted in 20 putative immunophilins comprising of 11 cyclophilins (CYPs), 7 FK506-binding proteins (FKBPs) and 2 parvulin-like proteins. RNAseq data showed that immunophilins were differentially regulated in enriched life stages such as germinating spores, maturing spores, and plasmodia, and infected Brassica hosts (B. rapa, B. napus and B. oleracea). PbCYP3 was highly induced in all studied life stages and during infection of all three Brassica hosts, and hence was selected for further analysis. PbCYP3 was heterologously expressed in Magnaporthe oryzae gene-inactivated ΔCyp1 strain. The new strain ΔCyp1+ overexpressing PbCYP3 showed increased virulence on rice compared to the ΔCyp1 strain. These results suggest that the predicted immunophilins and particularly PbCYP3 are activated during plant infection. M. oryzae is a well-studied fungal pathogen and could be a valuable tool for future functional studies of P. brassicae genes, particularly elucidating their role during various infection phases.
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