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ВґAnaeramoebaВґ - new lineage within Metamonada

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· “PROTIST–2016”
the transfer of genes from the endosymbiont to host
(EGT), the presence of such genes indicates past
endosymbiosis. To test the plastid-early hypothesis
and to learn more about the contribution of EGT to
euglenid genome, we have analyzed transcriptomes
of 5 euglenids (2 osmotrophic, 3 autotrophic) using a
pipeline, which enabled us to select genes related to
algae. The contribution of algal genes in autotrophic
euglenids (around 2 % of genes) is higher than in
primary osmotrophs (around 0.07 %) supporting the
plastid-late hypothesis. Surprisingly, we observed a
high number of genes related to other algal groups
than green algae.
CHARACTERIZATION OF A NOVEL PARAMECIUM ENDOSYMBIONT AND A CRITICAL REVISION OF “BASAL RICKETTSIALES”
Szokoli F.1,2, Schrallhammer M.3, Sabaneyeva E.4,
Castelli M.2, Krenek S.1, Doak T.G.5,6, Verni F.2,
Berendonk T.U.1, Petroni G.2
1
- Institut für Hydrobiologie, Technische Universität
Dresden, Germany
2
- Dipartimento di Biologia, Università di Pisa, Italy
3
- Mikrobiologie, Institut für Biologie II, AlbertLudwigs-Universität Freiburg, Germany
4
- Department of Cytology and Histology, St.
Petersburg State University, Russia
5
- Biology, Indiana University, IN, USA
6
- National Center for Genome Analysis Support,
IN, USA
Franziska.Szokoli@tu-dresden.de
In the past ten years, the number of newly described endosymbionts within the bacterial order
Rickettsiales has constantly grown, and 18 novel
Rickettsiales genera inhabiting protists—such as
ciliates or amoeba—have been described since 2006.
Half of these new species belong to the recently
proposed family “Candidatus Midichloriaceae”,
whereas five novel bacterial symbionts were found
belonging to Rickettsiaceae and six belonging
to Holosporaceae and other Rickettsiales with
uncertain position (“basal Rickettsiales”). In this
work, we provide molecular and ultrastructural
data on a novel bacterial endosymbiont inhabiting
a Paramecium biaurelia isolate collected near
Bloomington, Indiana (USA). We propose the
name “Candidatus Jurandia parameciophila” in
honor of Dr. Artur Jurand. The Gram-negative
bacteria (1.5-2.0 × 0.35-0.38 µm in size) occupies
the host cytoplasm and is devoid of flagella. For
molecular characterization, the SSU rRNA gene
was sequenced and used for taxonomic assignment and the design of species-specific oligonucleotide probes. Phylogenetic analyses indicate
that the endosymbiont belongs to “basal Ricket-
tsiales” (Alphaproteobacteria), clustering with the
recently proposed family “Candidatus Paracaedibacteraceae”. We obtained tree topologies showing a strong separation of Rickettsiales into at
least two groups; one represented by the families
Rickettsiaceae, Anaplasmataceae, and “Candidatus Midichloriaceae”, the so-called RAM clade,
and the other group represented by “basal Rickettsiales” including “Candidatus Jurandia parameciophila”. Therefore, and in accordance with
other recent publications, we propose to limit
the order Rickettsiales to the RAM clade and rise
“basal Rickettsiales” to an independent order,
Holosporales ord. nov., inside Alphaproteobacteria,
presently comprising four clades at the family level.
´ANAERAMOEBA´ - NEW LINEAGE WITHIN
METAMONADA
Táborský P.1, Pánek T.1,2, Kolisko M.3, Čepička I.1
1
- Department of Zoology, Charles University in
Prague, Prague, Czech Republic
2
- Department of Biology and Ecology Faculty of
Science University of Ostrava Chittussiho 10, Ostrava,
710 00
3
- Department of Botany, University of British
Columbia, Vancouver, British Columbia, Canada
taborsky.1988@gmail.com
We have isolated and cultured nine strains of
anaerobic amoebae (´Anaeramoeba´) from marine
coastal hypoxic sediments worldwide. ´Anaeramoeba´ cells were fan-shaped, with extremely
flattened pseudopodia and trailing uroidal filaments,
and morphologically belonging to flamellian
or flabellate morphotype. We distinguished six
morphospecies that differed in a number of features
including cell size and nuclear morphology. ´Anaeramoeba ´ species shared a unique combination
of morphological features. All three strains examined by TEM possessed double membranebound organelles with no cristae, presumably
hydrogenosomes, associated with prokaryotes
(probably methanogens). Cytoplasm contained a
large acentriolar centrosome, and no basal bodies
were observed. Peculiar isokont flagellates with two
or four flagella were rarely observed in two strains
representing different species. Single- and also fivegene analyses showed that ´Anaeramoeba´ clade
was monophyletic, but were completely unable
to assess its phylogenetic position. We analysed
transcriptomic data of two ´Anaeramoeba´species.
Phylogenomic analysis based on 160 protein-coding
genes surprisingly showed that ´Anaeramoeba ´
instead of being a member of Amoebozoa, represents
a novel deep lineage within Metamonada (Eukaryota:
Excavata).
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metamonada, lineage, вґanaeramoebaвґ, within, new
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