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Wyświetlanie 1-3 z 3
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:
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
    Wyświetlanie 1-3 z 3

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