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1.
Eur J Protistol ; 92: 126035, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38100884

RESUMO

Benthic foraminifera are unicellular eukaryotic protists that construct an organic, agglutinated, or calcareous test wall. Although single-chambered (monothalamous) foraminifera are ubiquitous in marine habitats worldwide, they are poorly known compared to their multi-chambered relatives, notably from the tropical marine environments of India. In this study, we describe two new species of marine monothalamid genus Psammophaga Arnold, 1982, from the Rajapuri Creek, coastal Maharashtra, India (Arabian Sea). Psammophaga holzmannae sp. nov. is ovoid to spherical shaped, 103-246 µm in length, single aperture, translucent to orange color cytoplasm, outer surface is composed of agglutinated fine clay particles, and ingested mineral grains are concentrated near its aperture. Psammophaga sinhai sp. nov. is oblong, elliptical, or droplet-shaped, 279-448 µm in length, single aperture, yellow olive color cytoplasm, the exterior surface formed of agglutinated fine clay particles, and the ingested mineral grains are dispersed throughout the body. Phylogenetic analyses based on partial small subunit rRNA gene sequences position new species within the Clade E of monothalamids and are genetically distinct from other Psammophaga. Elemental (SEM-EDS) analysis of engulfed mineral grains revealed preferential selection and uptake of heavy opaque titaniferous minerals from the ambient environment in the cytoplasm.


Assuntos
Foraminíferos , Rhizaria , Filogenia , Argila , Índia , Minerais
2.
Eur J Protistol ; 90: 126004, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37459806

RESUMO

The protist genus Gromia was first described in 1835 by Dujardin and while gromiids are prominent in the marine environment, Gromia oviformis was, for a long time, the only valid species regularly recorded. To date, 16 species that are morphologically and/or genetically distinct have been described. While recent studies are documenting their diversity and their ecological importance, G. oviformis has been the sole gromiid species identified in the Black Sea, although unnamed Gromia species have also been recorded. We collected sediment samples from the Romanian continental shelf at varying depths (48 - 58 m) to study the morphological and genetic diversity of gromiids in this part of the Black Sea. Three new species, Gromia bugnae sp. nov., Gromia dianae sp. nov. and Gromia fabi sp. nov., were identified based on an integrative taxonomic approach, thus bringing the total described gromiid species to 19. Analysis of partial SSU rRNA gene sequences confirms that these are distinct species. Additionally, an undescribed species is represented by a sequence from the northern part of the Black Sea (Sevastopol, Kazachya Bay). The study provides further evidence of the diversity of gromiids in the Black Sea and underlines the importance of this little-known group in marginal seas.


Assuntos
Rhizaria , Mar Negro , Romênia , Eucariotos , Oceanos e Mares , Filogenia
3.
Proc Natl Acad Sci U S A ; 120(27): e2221595120, 2023 07 04.
Artigo em Inglês | MEDLINE | ID: mdl-37364116

RESUMO

The chromatophores in Paulinella are evolutionary-early-stage photosynthetic organelles. Biological processes in chromatophores depend on a combination of chromatophore and nucleus-encoded proteins. Interestingly, besides proteins carrying chromatophore-targeting signals, a large arsenal of short chromatophore-targeted proteins (sCTPs; <90 amino acids) without recognizable targeting signals were found in chromatophores. This situation resembles endosymbionts in plants and insects that are manipulated by host-derived antimicrobial peptides. Previously, we identified an expanded family of sCTPs of unknown function, named here "DNA-binding (DB)-sCTPs". DB-sCTPs contain a ~45 amino acid motif that is conserved in some bacterial proteins with predicted functions in DNA processing. Here, we explored antimicrobial activity, DNA-binding capacity, and structures of three purified recombinant DB-sCTPs. All three proteins exhibited antimicrobial activity against bacteria involving membrane permeabilization, and bound to bacterial lipids in vitro. A combination of in vitro assays demonstrated binding of recombinant DB-sCTPs to chromatophore-derived genomic DNA sequences with an affinity in the low nM range. Additionally, we report the 1.2 Å crystal structure of one DB-sCTP. In silico docking studies suggest that helix α2 inserts into the DNA major grove and the exposed residues, that are highly variable between different DB-sCTPs, confer interaction with the DNA bases. Identification of photosystem II subunit CP43 as a potential interaction partner of one DB-sCTP, suggests DB-sCTPs to be involved in more complex regulatory mechanisms. We hypothesize that membrane binding of DB-sCTPs is related to their import into chromatophores. Once inside, they interact with the chromatophore genome potentially providing nuclear control over genetic information processing.


Assuntos
Anti-Infecciosos , Cromatóforos , Rhizaria , Evolução Biológica , Fotossíntese/genética , Cromatóforos/metabolismo , Anti-Infecciosos/metabolismo
4.
mBio ; 14(2): e0030223, 2023 04 25.
Artigo em Inglês | MEDLINE | ID: mdl-36939357

RESUMO

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.


Assuntos
Foraminíferos , Genoma Mitocondrial , Rhizaria , Animais , Foraminíferos/genética , Filogenia , Códon de Terminação , Rhizaria/genética , Genômica , Eucariotos/genética , Aminoácidos/genética , DNA Mitocondrial/genética
5.
New Phytol ; 238(5): 2130-2143, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-36810975

RESUMO

Phytomyxea are intracellular biotrophic parasites infecting plants and stramenopiles, including the agriculturally impactful Plasmodiophora brassicae and the brown seaweed pathogen Maullinia ectocarpii. They belong to the clade Rhizaria, where phagotrophy is the main mode of nutrition. Phagocytosis is a complex trait of eukaryotes, well documented for free-living unicellular eukaryotes and specific cellular types of animals. Data on phagocytosis in intracellular, biotrophic parasites are scant. Phagocytosis, where parts of the host cell are consumed at once, is seemingly at odds with intracellular biotrophy. Here we provide evidence that phagotrophy is part of the nutritional strategy of Phytomyxea, using morphological and genetic data (including a novel transcriptome of M. ectocarpii). We document intracellular phagocytosis in P. brassicae and M. ectocarpii by transmission electron microscopy and fluorescent in situ hybridization. Our investigations confirm molecular signatures of phagocytosis in Phytomyxea and hint at a small specialized subset of genes used for intracellular phagocytosis. Microscopic evidence confirms the existence of intracellular phagocytosis, which in Phytomyxea targets primarily host organelles. Phagocytosis seems to coexist with the manipulation of host physiology typical of biotrophic interactions. Our findings resolve long debated questions on the feeding behaviour of Phytomyxea, suggesting an unrecognized role for phagocytosis in biotrophic interactions.


Assuntos
Parasitos , Rhizaria , Animais , Parasitos/genética , Rhizaria/genética , Hibridização in Situ Fluorescente , Fagocitose
6.
Genome Biol Evol ; 15(3)2023 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-36790104

RESUMO

Ascetosporea are endoparasites of marine invertebrates that include economically important pathogens of aquaculture species. Owing to their often-minuscule cell sizes, strict intracellular lifestyle, lack of cultured representatives and minimal availability of molecular data, these unicellular parasites remain poorly studied. Here, we sequenced and assembled the genome and transcriptome of Paramikrocytos canceri, an endoparasite isolated from the European edible crab Cancer pagurus. Using bioinformatic predictions, we show that P. canceri likely possesses a mitochondrion-related organelle (MRO) with highly reduced metabolism, resembling the mitosomes of other parasites but with key differences. Like other mitosomes, this MRO is predicted to have reduced metabolic capacity and lack an organellar genome and function in iron-sulfur cluster (ISC) pathway-mediated Fe-S cluster biosynthesis. However, the MRO in P. canceri is uniquely predicted to produce ATP via a partial glycolytic pathway and synthesize phospholipids de novo through the CDP-DAG pathway. Heterologous gene expression confirmed that proteins from the ISC and CDP-DAG pathways retain mitochondrial targeting sequences that are recognized by yeast mitochondria. This represents a unique combination of metabolic pathways in an MRO, including the first reported case of a mitosome-like organelle able to synthesize phospholipids de novo. Some of these phospholipids, such as phosphatidylserine, are vital in other protist endoparasites that invade their host through apoptotic mimicry.


Assuntos
Parasitos , Rhizaria , Animais , Rhizaria/genética , Organelas , Mitocôndrias/genética , Mitocôndrias/metabolismo , Saccharomyces cerevisiae/metabolismo
7.
Bioessays ; 45(1): e2200165, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36328783

RESUMO

We hypothesize that as one of the most consequential events in evolution, primary endosymbiosis accelerates lineage divergence, a process we refer to as the endosymbiotic ratchet. Our proposal is supported by recent work on the photosynthetic amoeba, Paulinella, that underwent primary plastid endosymbiosis about 124 Mya. This amoeba model allows us to explore the early impacts of photosynthetic organelle (plastid) origin on the host lineage. The current data point to a central role for effective population size (Ne ) in accelerating divergence post-endosymbiosis due to limits to dispersal and reproductive isolation that reduce Ne , leading to local adaptation. We posit that isolated populations exploit different strategies and behaviors and assort themselves in non-overlapping niches to minimize competition during the early, rapid evolutionary phase of organelle integration. The endosymbiotic ratchet provides a general framework for interpreting post-endosymbiosis lineage evolution that is driven by disruptive selection and demographic and population shifts. Also see the video abstract here: https://youtu.be/gYXrFM6Zz6Q.


Assuntos
Rhizaria , Simbiose , Plastídeos , Fotossíntese , Filogenia , Evolução Biológica
9.
Eur J Protistol ; 86: 125932, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36347189

RESUMO

Single-chambered (monothalamous) foraminifera are poorly known compared to their multichambered relatives. In this first study of monothalamids from Greenland, we describe one new genus and two new species belonging to different clades from the Nuuk fjord system. Nujappikia idaliae Gooday & Holzmann gen. nov. sp. nov. (Clade Y) has a bottle-shaped test terminating in a single aperture located on a short neck. The flexible wall is basically organic but with a very fine agglutinated veneer. Bathyallogromia kalaallita Gooday & Holzmann sp. nov. (Clade C) has a broadly ovate test with an organic wall and a mound-like apertural structure. It is larger and genetically distinct from the two other Bathyallogromia species, both from the Southern Ocean. A survey of the morphological diversity of monothalamids in our samples revealed 49 morphospecies, of which 19, including the two new species, yielded DNA sequences. Five were assigned to the genera Bathysiphon, (Clade BM), Micrometula. (Clade BM), Psammophaga. (Clade E), Hippocrepinella (Clade D) and Crithionina (Clade J). The remaining twelve represented unknown taxa branching in clades A, C, F, and Y and one new clade. Our results add to growing evidence that monothalamids are common and diverse in fjords and other high-latitude settings.


Assuntos
Foraminíferos , Rhizaria , Foraminíferos/genética , Rhizaria/genética , Groenlândia , Filogenia , Análise de Sequência de DNA
10.
Appl Environ Microbiol ; 88(22): e0121522, 2022 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-36300943

RESUMO

The large-scale culture of low-cost algal biomass can be significantly affected by microbial grazing on the algae. To minimize the impact, it is necessary to manage the predators. In this study, we describe a new genus and species of vampyrellid amoeba, Kinopus chlorellivorus, which caused the loss of Chlorella sorokiniana in large-scale cultures. We assigned it to the family Leptophryidae (Vampyrellida) based on morphology and small-subunit (SSU) rRNA gene sequence comparisons. Using transmission electron microscopy, we found spherical lucent inclusions, which have not been reported for any leptophryids or other vampyrellids. The gene sequence of SSU rRNA did not match any recognized genera or species and contained four characteristic regions. K. chlorellivorus preys on algae by engulfment. Laboratory feeding experiments confirmed that its grazing rate was as high as 131 Chlorella cells day-1 individual-1. Results of prey-range experiments demonstrated that it could consume other chlorophyte microalgae (e.g., Scenedesmus, Coelastrella, and Haematococcus) but with a strong feeding ability on Chlorella spp., with ingestion rates ranging from 2.67 to 3.15 prey predator-1 h-1 and growth rates of the amoeba ranging from 0.039 to 0.045 h-1. On the basis of its high grazing ability on Chlorella, capacity to form large populations in a short period of time, and capacity to form resistant resting stages, this contaminant has the potential to cause serious problems in large-scale Chlorella culture and should be of concern to operators of algal production facilities. IMPORTANCE The vampyrellids (Vampyrellida, Rhizaria) are a major group of predatory amoebae that have attracted significant attention because of their diversity of feeding strategies. The crucial roles they play in important processes such as suppressing soil disease and controlling aquatic algae, and as microbial contaminants in outdoor large-scale algal cultures, have also received increasing attention. In this study, a new genus and species of algivorous vampyrellid amoeba, Kinopus chlorellivorus, is described as a significant grazer responsible for losses in outdoor industrial Chlorella cultures. We found that the amoeba's detrimental effects on Chlorella cultures may be related to its specific feeding characteristics. This study provides phenotypic and genetic information on a previously unknown vampyrellid, emphasizes the impact of contaminating vampyrellids in commercial microalgal cultures, and will contribute to the development of management strategies for predicting this kind of contaminant in large-scale microalgal cultivation.


Assuntos
Amoeba , Cercozoários , Chlorella , Microalgas , Rhizaria , Scenedesmus , Cercozoários/genética , Biomassa
11.
Zootaxa ; 5160(1): 1-158, 2022 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-36095528

RESUMO

Lophophaenidae is a clade of polycystine radiolarians that was highly abundant and diverse in the Late NeogeneRecent eastern equatorial Pacific (EEP). Despite their importance in fossil plankton assemblages, lophophaenids have been neglected because of their generally small size, complex morphology, and weak taxonomic framework. These challenges have left many lophophaenid concepts poorly defined or lacking formal description. Here we address this with a review of 101 lophophaenid taxa observed in EEP Middle MioceneRecent marine sediments. We discuss existing lophophaenid genera Amphiplecta Haeckel 1881, Arachnocorallium Haeckel 1887, Arachnocorys Haeckel 1860, Botryopera Haeckel 1887, Ceratocyrtis Btschli 1882, Lithomelissa Ehrenberg 1847, Lophophaena Ehrenberg 1847, and Peromelissa Haeckel 1881, including full species lists. We describe Pelagomanes n. gen., 23 new species: Amphiplecta kikimorae n. sp., Arachnocorys jorogumoae n. sp., Botryopera amabie n. sp., Botryopera babayagae n. sp., Botryopera bolotniki n. sp., Ceratocyrtis? chimii n. sp., Ceratocyrtis vila n. sp., Lithomelissa alkonost n. sp., Lithomelissa babai n. sp., Lithomelissa dybbuki n. sp., Lithomelissa sirin n. sp., Lophophaena arie n. sp., Lophophaena casperi n. sp., Lophophaena domovoi n. sp., Lophophaena gozui n. sp., Lophophaena ikiryo n. sp., Lophophaena ikota n. sp., Lophophaena kaonashii n. sp., Lophophaena leshii n. sp., Lophophaena rusalkae n. sp., Lophophaena shishigae n. sp., Lophophaena ushionii n. sp., and Pelagomanes ibburi n. sp., and one new subspecies, Arachnocorys pentacantha wanii n. subsp. In addition, we document 35 taxa in open nomenclature, and revise generic assignments of 10 species. The names of 32 previously-described species are upheld, but with clarified synonymies, discussion, and illustrations. This work contributes a practical framework for identifying tropical Late NeogeneRecent lophophaenid taxa, and demonstrates their rich morphological diversity.


Assuntos
Rhizaria , Animais , Fósseis , Plâncton
12.
PLoS One ; 17(7): e0270913, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35895712

RESUMO

Many species of plants have evolved structures called phytotelmata that store water and trap detritus and prey. These structures house diverse communities of organisms, the inquiline microbiome, that aids breakdown of litter and prey. The invertebrate and bacterial food webs in these systems are well characterized, but less is known about microbial eukaryotic community dynamics. In this study we focus on microbes in the SAR clade (Stramenopila, Alveolata, Rhizaria) inhabiting phytotelmata. Using small subunit rDNA amplicon sequencing from repeated temporal and geographic samples of wild and cultivated plants across the Northeast U.S.A., we demonstrate that communities are variable within and between host plant type. Across habitats, communities from tropical bromeliads grown in a single room of a greenhouse were nearly as heterogeneous as wild pitcher plants spread across hundreds of kilometers. At the scale of pitcher plants in a single bog, analyses of samples from three time points suggest that seasonality is a major driver of protist community structure, with variable spring communities transitioning to more homogeneous communities that resemble the surrounding habitat. Our results indicate that protist communities in phytotelmata are variable, likely due to stochastic founder events and colonization/competition dynamics, leading to tremendous heterogeneity in inquiline microeukaryotic communities.


Assuntos
Microbiota , Rhizaria , Bactérias/genética , Eucariotos/genética , Cadeia Alimentar , Microbiota/genética , Plantas
13.
Mol Phylogenet Evol ; 174: 107546, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35690380

RESUMO

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.


Assuntos
Foraminíferos , Rhizaria , Evolução Biológica , Foraminíferos/genética , Filogenia , RNA Ribossômico 18S/genética , Rhizaria/genética , Transcriptoma
14.
Proc Natl Acad Sci U S A ; 119(23): e2121241119, 2022 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-35639693

RESUMO

The evolution of eukaryotic life was predicated on the development of organelles such as mitochondria and plastids. During this complex process of organellogenesis, the host cell and the engulfed prokaryote became genetically codependent, with the integration of genes from the endosymbiont into the host nuclear genome and subsequent gene loss from the endosymbiont. This process required that horizontally transferred genes become active and properly regulated despite inherent differences in genetic features between donor (endosymbiont) and recipient (host). Although this genetic reorganization is considered critical for early stages of organellogenesis, we have little knowledge about the mechanisms governing this process. The photosynthetic amoeba Paulinella micropora offers a unique opportunity to study early evolutionary events associated with organellogenesis and primary endosymbiosis. This amoeba harbors a "chromatophore," a nascent photosynthetic organelle derived from a relatively recent cyanobacterial association (∼120 million years ago) that is independent of the evolution of primary plastids in plants (initiated ∼1.5 billion years ago). Analysis of the genome and transcriptome of Paulinella revealed that retrotransposition of endosymbiont-derived nuclear genes was critical for their domestication in the host. These retrocopied genes involved in photoprotection in cyanobacteria became expanded gene families and were "rewired," acquiring light-responsive regulatory elements that function in the host. The establishment of host control of endosymbiont-derived genes likely enabled the cell to withstand photo-oxidative stress generated by oxygenic photosynthesis in the nascent organelle. These results provide insights into the genetic mechanisms and evolutionary pressures that facilitated the metabolic integration of the host­endosymbiont association and sustained the evolution of a photosynthetic organelle.


Assuntos
Amoeba , Evolução Biológica , Rhizaria , Simbiose , Amoeba/genética , Eucariotos/genética , Plastídeos/genética , Simbiose/genética
15.
Environ Microbiol ; 24(7): 2979-2993, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35621046

RESUMO

Ribosomal RNA (rRNA) genes are known to be valuable markers for the barcoding of eukaryotic life and its phylogenetic classification at various taxonomic levels. The large-scale exploration of environmental microbial diversity through metabarcoding approaches has been focused mainly on the V4 and V9 regions of the 18S rRNA gene. The accurate interpretation of such environmental surveys is hampered by technical (e.g. PCR and sequencing errors) and biological biases (e.g. intra-genomic variability). Here we explored the intra-genomic diversity of Nassellaria and Spumellaria specimens (Radiolaria) by comparing Sanger sequencing with Illumina and Oxford Nanopore Technologies (MinION). Our analysis determined that intra-genomic variability of Nassellaria and Spumellaria is generally low, yet some Spumellaria specimens showed two different copies of the V4 with <97% similarity. Of the different sequencing methods, Illumina showed the highest number of contaminations (i.e. environmental DNA, cross-contamination, tag-jumping), revealed by its high sequencing depth; and MinION showed the highest sequencing rate error (~14%). Yet the long reads produced by MinION (~2900 bp) allowed accurate phylogenetic reconstruction studies. These results highlight the requirement for a careful interpretation of Illumina-based metabarcoding studies, in particular regarding low abundant amplicons, and open future perspectives towards full-length rDNA environmental metabarcoding surveys.


Assuntos
Rhizaria , Genes de RNAr , Genômica , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Filogenia , Rhizaria/genética , Análise de Sequência de DNA
16.
J Eukaryot Microbiol ; 69(4): e12924, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35593513

RESUMO

This study reports the first record of Sorosphaerula radicalis (Phytomyxea, Rhizaria) in continental Europe (Tirol, Austria) and provides first molecular data for this species. An 18S rRNA phylogeny placed S. radicalis into the Plasmodiophorida, although distant from other members of the genus Sorosphaerula and close to the parasite of water cress Hillenburgia nasturtii. To resolve this polyphyly, we compare morphological data and life cycles of Sorosphaerula veronicae (the type species of the genus Sorosphaerula), Hillenburgia nasturtii, and Sorosphaerula radicalis. We conclude that Sorosphaerula radicalis belongs to the recently established genus Hillenburgia.


Assuntos
Plasmodioforídeos , Rhizaria , Filogenia , Plasmodioforídeos/genética , RNA Ribossômico 18S/genética
17.
J Eukaryot Microbiol ; 69(3): e12905, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35303760

RESUMO

Hermesinum adriaticum is a rare marine and brackish flagellate that is of considerable interest due to its markable and fossilizable siliceous skeleton. Based on this skeleton, Hermesinum was initially considered a microalga of the Dictyochophyceae (Ochrophyta, Stramenopiles). Later on, it was assigned to the Ebriida due to its similarity to Ebria tripartita. The taxonomic assignment of the Ebriida, however, changed several times until it was placed within the Thecofilosea (Cercozoa, Rhizaria), based on genetic data of E. tripartita. We sequenced the 18S marker gene sequence of Hermesinum and confirm the close relationship of Ebria and Hermesinum.


Assuntos
Cercozoários , Rhizaria , Cercozoários/genética , Filogenia , Rhizaria/genética
18.
Mol Ecol ; 31(9): 2644-2663, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35262986

RESUMO

The salinity barrier that separates marine and freshwater biomes is probably the most important division in biodiversity on Earth. Those organisms that successfully performed this transition had access to new ecosystems while undergoing changes in selective pressure, which often led to major shifts in diversification rates. While these transitions have been extensively investigated in animals, the tempo, mode, and outcome of crossing the salinity barrier have been scarcely studied in other eukaryotes. Here, we reconstructed the evolutionary history of the species complex Cyphoderia ampulla (Euglyphida: Cercozoa: Rhizaria) based on DNA sequences from the nuclear SSU rRNA gene and the mitochondrial cytochrome oxidase subunit I gene, obtained from publicly available environmental DNA data (GeneBank, EukBank) and isolated organisms. A tree calibrated with euglyphid fossils showed that four independent transitions towards freshwater systems occurred from the mid-Miocene onwards, coincident with important fluctuations in sea level. Ancestral trait reconstructions indicated that the whole family Cyphoderiidae had a marine origin and suggest that ancestors of the freshwater forms were euryhaline and lived in environments with fluctuating salinity. Diversification rates did not show any obvious increase concomitant with ecological transitions, but morphometric analyses indicated that species increased in size and homogenized their morphology after colonizing the new environments. This suggests adaptation to changes in selective pressure exerted by life in freshwater sediments.


Assuntos
Militares , Rhizaria , Animais , Ecossistema , Eucariotos , Água Doce , Humanos , Filogenia , Salinidade
19.
J Phycol ; 58(3): 392-405, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35255163

RESUMO

Plastid primary endosymbiosis has occurred twice, once in the Archaeplastida ancestor and once in the Paulinella (Rhizaria) lineage. Both events precipitated massive evolutionary changes, including the recruitment and activation of genes that are horizontally acquired (HGT) and the redeployment of existing genes and pathways in novel contexts. Here we address the latter aspect in Paulinella micropora KR01 (hereafter, KR01) that has independently evolved spliced leader (SL) trans-splicing (SLTS) of nuclear-derived transcripts. We investigated the role of this process in gene regulation, novel gene origination, and endosymbiont integration. Our analysis shows that 20% of KR01 genes give rise to transcripts with at least one (but in some cases, multiple) sites of SL addition. This process, which often occurs at canonical cis-splicing acceptor sites (internal introns), results in shorter transcripts that may produce 5'-truncated proteins with novel functions. SL-truncated transcripts fall into four categories that may show: (i) altered protein localization, (ii) altered protein function, structure, or regulation, (iii) loss of valid alternative start codons, preventing translation, or (iv) multiple SL addition sites at the 5'-terminus. The SL RNA genes required for SLTS are putatively absent in the heterotrophic sister lineage of photosynthetic Paulinella species. Moreover, a high proportion of transcripts derived from genes of endosymbiotic gene transfer (EGT) and HGT origin contain SL sequences. We hypothesize that truncation of transcripts by SL addition may facilitate the generation and expression of novel gene variants and that SLTS may have enhanced the activation and fixation of foreign genes in the host genome of the photosynthetic lineages, playing a key role in primary endosymbiont integration.


Assuntos
Amoeba , Rhizaria , Amoeba/genética , Amoeba/metabolismo , Evolução Biológica , RNA Líder para Processamento/genética , RNA Líder para Processamento/metabolismo , Trans-Splicing
20.
Sci Rep ; 12(1): 2848, 2022 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-35181716

RESUMO

We clarified the specific micrometric arrangement and nanometric structure of the radiolarian crystalline spines that are not a simple single crystal. A body of the celestite (SrSO4) skeleton of acantharian Acanthometra cf. multispina (Acanthometridae) composed of 20 radial spines having four blades was characterized using microfocus X-ray computed tomography. The regular arrangement of three types of spines was clarified with the connection of the blades around the root of each spine. The surface of the spines was covered with a chitin-based organic membrane to prevent from dissolution in seawater. In the nanometric scale, the mesocrystalline structure that consists of nanoscale grains having distorted single-crystal nature was revealed using scanning- and transmission electron microscopies, electron diffraction, and Raman spectroscopy. The acantharian skeletons have a crystallographically controlled architecture that is covered with a protective organic membrane. These facts are important for penetrating the nature of biogenic minerals.


Assuntos
Rhizaria/ultraestrutura , Esqueleto/anatomia & histologia , Microscopia Eletrônica de Transmissão , Minerais/metabolismo , Sistema Musculoesquelético/anatomia & histologia , Sistema Musculoesquelético/ultraestrutura , Filogenia , Água do Mar , Esqueleto/ultraestrutura , Análise Espectral Raman
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