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    Wyświetlanie 1-7 z 7
    Tytuł:
    Primary endosymbiosis: have cyanobacteria and Chlamydiae ever been roommates?
    Autorzy:
    Deschamps, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/56711.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Botaniczne
    Tematy:
    primary endosymbiosis
    endosymbiosis
    Cyanoprokaryota
    Chlamydia
    Archaeplastida
    gene transfer
    photosynthesis
    Opis:
    Eukaryotes acquired the ability to process photosynthesis by engulfing a cyanobacterium and transforming it into a genuine organelle called the plastid. This event, named primary endosymbiosis, occurred once more than a billion years ago, and allowed the emergence of the Archaeplastida, a monophyletic supergroup comprising the green algae and plants, the red algae and the glaucophytes. Of the other known cases of symbiosis between cyanobacteria and eukaryotes, none has achieved a comparable level of cell integration nor reached the same evolutionary and ecological success than primary endosymbiosis did. Reasons for this unique accomplishment are still unknown and difficult to comprehend. The exploration of plant genomes has revealed a considerable amount of genes closely related to homologs of Chlamydiae bacteria, and probably acquired by horizontal gene transfer. Several studies have proposed that these transferred genes, which are mostly involved in the functioning of the plastid, may have helped the settlement of primary endosymbiosis. Some of these studies propose that Chlamydiae and cyanobacterial symbionts coexisted in the eukaryotic host of the primary endosymbiosis, and that Chlamydiae provided solutions for the metabolic symbiosis between the cyanobacterium and the host, ensuring the success of primary endosymbiosis. In this review, I present a reevaluation of the contribution of Chlamydiae genes to the genome of Archaeplastida and discuss the strengths and weaknesses of this tripartite model for primary endosymbiosis.
    Źródło:
    Acta Societatis Botanicorum Poloniae; 2014, 83, 4
    0001-6977
    2083-9480
    Pojawia się w:
    Acta Societatis Botanicorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Plastid origin: who, when and why?
    Autorzy:
    Ku, Chuan
    Roettger, M.
    Zimorski, V.
    Nelsen-Sathi, S.
    Sousa, F.L.
    Martin, W.F.
    Powiązania:
    https://bibliotekanauki.pl/articles/59262.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Botaniczne
    Tematy:
    plastid
    Cyanoprokaryota
    endosymbiosis
    evolution
    gene transfer
    genomics
    organelle
    photosynthesis
    phylogenesis
    Opis:
    The origin of plastids is best explained by endosymbiotic theory, which dates back to the early 1900s. Three lines of evidence based on protein import machineries and molecular phylogenies of eukaryote (host) and cyanobacterial (endosymbiont) genes point to a single origin of primary plastids, a unique and important event that successfully transferred two photosystems and oxygenic photosynthesis from prokaryotes to eukaryotes. The nature of the cyanobacterial lineage from which plastids originated has been a topic of investigation. Recent studies have focused on the branching position of the plastid lineage in the phylogeny based on cyanobacterial core genes, that is, genes shared by all cyanobacteria and plastids. These studies have delivered conflicting results, however. In addition, the core genes represent only a very small portion of cyanobacterial genomes and may not be a good proxy for the rest of the ancestral plastid genome. Information in plant nuclear genomes, where most genes that entered the eukaryotic lineage through acquisition from the plastid ancestor reside, suggests that heterocyst-forming cyanobacteria in Stanier’s sections IV and V are most similar to the plastid ancestor in terms of gene complement and sequence conservation, which is in agreement with models suggesting an important role of nitrogen fixation in symbioses involving cyanobacteria. Plastid origin is an ancient event that involved a prokaryotic symbiont and a eukaryotic host, organisms with different histories and genome evolutionary processes. The different modes of genome evolution in prokaryotes and eukaryotes bear upon our interpretations of plastid phylogeny.
    Źródło:
    Acta Societatis Botanicorum Poloniae; 2014, 83, 4
    0001-6977
    2083-9480
    Pojawia się w:
    Acta Societatis Botanicorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Acquisition of Plastids/Phototrophy in Heterotrophic Dinoflagellates
    Autorzy:
    Park, Myung Gil
    Kim, Miran
    Kim, Sunju
    Powiązania:
    https://bibliotekanauki.pl/articles/763559.pdf
    Data publikacji:
    2014
    Wydawca:
    Uniwersytet Jagielloński. Wydawnictwo Uniwersytetu Jagiellońskiego
    Tematy:
    Acquired phototrophy, chloroplast, endosymbiont, endosymbiosis, kleptoplastid, kleptoplasty, mixotrophy, organelle retention, photosynthesis
    Opis:
    Several dinoflagellates are known to practice acquired phototrophy by either hosting intact algal endosymbionts or retaining plastids. The acquisition of phototrophy in dinoflagellates appears to occur independently over a variety of orders, rather than being restricted to any specific order(s). While dinoflagellates with intact algal cells host endosymbionts of cyanobacteria, pelagophyte, prasinophyte or dictyochophyte, most organelle-retaining dinoflagellates acquire plastids from cryptophytes. In dinoflagellates with acquired phototrophy, the mechanism by which symbionts or plastids are obtained has not been well studied at sub-cellular or ultrastructural level, and thus little is known regarding their mechanism to sequester and maintain photosynthetic structures, except for three cases, Amphidinium poecilochroum, Gymnodinium aeruginosum, and Dinophysis caudata with peduncle feeding. Dinoflagellates with acquired phototrophy display different degrees of reduction of the retained endosymbiont and organelles, ranging from those which contain intact whole algal cells (e.g. green Noctiluca scintillans), to those which have retained almost a full complement of organelles (e.g., Amphidinium poecilochroum and Podolampas bipes), to those in which only the plastids remain (e.g., Amphidinium wigrense and Dinophysis spp.). A series of events leading to acquisition and subsequent degeneration of a whole-cell endosymbiont have been widely recognized as evolutionary pathway of the acquisition of plastids. However, recent work on D. caudata suggests that acquisition of phototrophy by predation (i.e. kleptoplastidy) may be a mechanism and evolutionary pathway through which plastids originated in dinoflagellates with ‘foreign’ plastids other than the ‘typical’ peridinin-type plastids. Most organelle-retaining dinoflagellates are facultative mixotrophs, with Dinophysis species and an undescribed Antarctic dinoflagellate being the only obligate mixotrophs known so far. The establishment of dinoflagellates with acquired phototrophy in cultures and careful research using the cultures would help improve our knowledge of the evolution of the dinoflagellate plastids and their ecophysiology.
    Źródło:
    Acta Protozoologica; 2014, 53, 1
    1689-0027
    Pojawia się w:
    Acta Protozoologica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Living Together in the Plankton: A Survey of Marine Protist Symbioses
    Autorzy:
    Anderson, O. Roger
    Powiązania:
    https://bibliotekanauki.pl/articles/763557.pdf
    Data publikacji:
    2014
    Wydawca:
    Uniwersytet Jagielloński. Wydawnictwo Uniwersytetu Jagiellońskiego
    Tematy:
    Algal symbionts, bacterial symbionts, marine endosymbiosis, microbial physiology, molecular genetics, plankton ecology
    Opis:
    Our best evidence is that life arose in the marine environment, and over many millennia of evolutionary proliferation, punctuated by occasional massive extinctions, marine protists have developed remarkably elegant and sometimes complex relationships with prokaryotic and eukaryotic symbionts. Current evidence of the range of marine protist taxa possessing symbionts, including their diversity and physiological functional relationships, is reviewed within an ecological context. Some perspectives are presented on potential opportunities for new avenues of research in unraveling the remarkable adaptive value of two or more genetically diverse marine unicellular organisms living in a close structural and physiological relationship.
    Źródło:
    Acta Protozoologica; 2014, 53, 1
    1689-0027
    Pojawia się w:
    Acta Protozoologica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Unique genome evolution in an intracellular N2-fixing symbiont of a rhopalodiacean diatom
    Autorzy:
    Nakayama, T.
    Inagaki, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/59328.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Botaniczne
    Tematy:
    nitrogen fixation
    endosymbiosis
    genome
    evolution
    genome reduction
    spheroid body
    symbiont
    rhopalodiacean diatom
    Cyanoprokaryota
    Opis:
    Cyanobacteria, the major photosynthetic prokaryotic lineage, are also known as a major nitrogen fixer in nature. N2-fixing cyanobacteria are frequently found in symbioses with various types of eukaryotes and supply fixed nitrogen compounds to their eukaryotic hosts, which congenitally lack N2-fixing abilities. Diatom species belonging to the family Rhopalodiaceae also possess cyanobacterial symbionts called spheroid bodies. Unlike other cyanobacterial N2-fixing symbionts, the spheroid bodies reside in the cytoplasm of the diatoms and are inseparable from their hosts. Recently, the first spheroid body genome from a rhopalodiacean diatom has been completely sequenced. Overall features of the genome sequence showed significant reductive genome evolution resulting in a diminution of metabolic capacity. Notably, despite its cyanobacterial origin, the spheroid body was shown to be truly incapable of photosynthesis implying that the symbiont energetically depends on the host diatom. The comparative genome analysis between the spheroid body and another N2-fixing symbiotic cyanobacterial group corresponding to the UCYN-A phylotypes – both were derived from cyanobacteria closely related to genus Cyanothece – revealed that the two symbionts are on similar, but explicitly distinct tracks of reductive evolution. Intimate symbiotic relationships linked by nitrogen fixation as seen in rhopalodiacean diatoms may help us better understand the evolution and mechanisms of bacterium-eukaryote endosymbioses.
    Źródło:
    Acta Societatis Botanicorum Poloniae; 2014, 83, 4
    0001-6977
    2083-9480
    Pojawia się w:
    Acta Societatis Botanicorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Paulinella chromatophora - rethinking the transition from endosymbiont to organelle
    Autorzy:
    Nowack, E.C.M.
    Powiązania:
    https://bibliotekanauki.pl/articles/57807.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Botaniczne
    Tematy:
    Paulinella chromatophora
    organellogenesis
    plastid
    evolution
    endosymbiosis
    Cyanoprokaryota
    photosynthesis
    chromatophore
    protein targeting
    endosymbiont
    organelle
    Rhizaria
    Opis:
    Eukaryotes co-opted photosynthetic carbon fixation from prokaryotes by engulfing a cyanobacterium and stably integrating it as a photosynthetic organelle (plastid) in a process known as primary endosymbiosis. The sheer complexity of interactions between a plastid and the surrounding cell that started to evolve over 1 billion years ago, make it challenging to reconstruct intermediate steps in organelle evolution by studying extant plastids. Recently, the photosynthetic amoeba Paulinella chromatophora was identified as a much sought-after intermediate stage in the evolution of a photosynthetic organelle. This article reviews the current knowledge on this unique organism. In particular it describes how the interplay of reductive genome evolution, gene transfers, and trafficking of host-encoded proteins into the cyanobacterial endosymbiont contributed to transform the symbiont into a nascent photosynthetic organelle. Together with recent results from various other endosymbiotic associations a picture emerges that lets the targeting of host-encoded proteins into bacterial endosymbionts appear as an early step in the establishment of an endosymbiotic relationship that enables the host to gain control over the endosymbiont.
    Źródło:
    Acta Societatis Botanicorum Poloniae; 2014, 83, 4
    0001-6977
    2083-9480
    Pojawia się w:
    Acta Societatis Botanicorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Protein translocons in photosynthetic organelles of Paulinella chromatophora
    Autorzy:
    Gagat, P.
    Mackiewicz, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/56561.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Botaniczne
    Tematy:
    photosynthesis
    organelle
    Paulinella chromatophora
    amoeba
    essential gene
    chromatophore
    endosymbiosis
    primary plastid
    plastid
    protein
    translocon zob.translocator
    translocator
    translocation channel zob.translocator
    Opis:
    The rhizarian amoeba Paulinella chromatophora harbors two photosynthetic cyanobacterial endosymbionts (chromatophores), acquired independently of primary plastids of glaucophytes, red algae and green plants. These endosymbionts have lost many essential genes, and transferred substantial number of genes to the host nuclear genome via endosymbiotic gene transfer (EGT), including those involved in photosynthesis. This indicates that, similar to primary plastids, Paulinella endosymbionts must have evolved a transport system to import their EGT-derived proteins. This system involves vesicular trafficking to the outer chromatophore membrane and presumably a simplified Tic-like complex at the inner chromatophore membrane. Since both sequenced Paulinella strains have been shown to undergo differential plastid gene losses, they do not have to possess the same set of Toc and Tic homologs. We searched the genome of Paulinella FK01 strain for potential Toc and Tic homologs, and compared the results with the data obtained for Paulinella CCAC 0185 strain, and 72 cyanobacteria, eight Archaeplastida as well as some other bacteria. Our studies revealed that chromatophore genomes from both Paulinella strains encode the same set of translocons that could potentially create a simplified but fully-functional Tic-like complex at the inner chromatophore membranes. The common maintenance of the same set of translocon proteins in two Paulinella strains suggests a similar import mechanism and/or supports the proposed model of protein import. Moreover, we have discovered a new putative Tic component, Tic62, a redox sensor protein not identified in previous comparative studies of Paulinella translocons.
    Źródło:
    Acta Societatis Botanicorum Poloniae; 2014, 83, 4
    0001-6977
    2083-9480
    Pojawia się w:
    Acta Societatis Botanicorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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