CC BY
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Protistology ■ 13
collections of microorganisms", St. Petersburg, Russia
2 - Institute ofCytology, Russian Academy ofSciences, St.Petersburg, Russia
3 - Zoological Institute of the Russian Academy of Sciences,St. Petersburg, Russia
4 - Life Science Research Centre, Faculty ofScience, University of Ostrava
At present the taxonomy of Archamoebae is based on molecular phylogeny, and it is problematic to find non-molecular synapomorphies for different lineages within this group. The family Pelomyxidae includes two archamoebal genera: Pelomyxa and Mastigella. All pelomyxae and most mastigellae have various prokaryotic endocytobionts. Host-symbiont composition could be useful for the phylogeny reconstruction, but information about such associations is controversial. We analyzed consortia of prokaryotic symbionts in Mastigella nitens and 11 Pelomyxa spp. There are two kinds of such consortia within pelomyxid cells: binary and ternary ones (with 2 and 3 symbionts correspondingly). The composition of these associations revealed to be species-specific. According to morphological characters, autofluorescence ability and results of Gram staining 4 main types of cytobionts can be distinguished. One of them is common to all investigated pelomyxae and M. nitens. Morphologically similar prokaryotes can be also found in the cytoplasm of other Mastigella spp. Distribution of the remaining types of cytobionts among hosts species is not correlated with the molecular phylogeny of Archamoebae based on 18S rRNA gene. We propose the ability to form symbiotic associations with prokaryotes as a shared feature of all Pelomyxidae. This work was supported by the grant RFBR 15-04-00396_a. Scientific research were performed at the Center for Culturing Collection ofMicroorganisms and "Chromas" Center of Research park of St. Petersburg State University.
THE GENOME EVOLUTION OF THE THER-MOACIDOPHILIC CYANIDALES RED ALGAE Cho C.H.1, Park S.I.1, Ciniglia C.2, Yoon H.S.1
1 - Department of Biological Sciences, Sungkyunkwan University, Korea
2 - Department of Environmental, Biological and Pharmaceutical Science and Technologies, Second University of Naples, Italy [email protected]
The Cyanidiales is an early diverged red algal group that comprised of seven species with numerous cryptic species. They are asexual, unicellular photosynthetic eukaryote, which usually thrive in
extremophilic environments (pH1.5~3, 35~55oC). Cyanidiales species are reported from hot springs around world including Yellowstone National Park (US), Italy, Iceland, New Zealand, Indonesia, and Japan. Some Cyanidiales species are also found in acidic bogs, mesophilic caves, interlithic or endolithic environments. In addition, they show trophic differences being either autotroph or mixotroph. From previous researches, the genomes of Cyanidiales are highly reduced, but horizontally acquired from bacteria to adopt in extreme habitats. Here we report two nuclear genomes of Galdieria maxima and Cyanidium caldarium and conduct comparative genome analysis with three available genomes of Cyanidioschyzon merolae, Galdieria sulphuraria, and Galdieriaphlegrea. We will discuss gene contents, mutation rates, and unique horizontal gene transfer that related to the environmental adaptation.
EVOLUTION OF HEME BIOSYNTHESIS PATHWAY IN ALGAE WITH COMPLEX PLASTIDS Cihlar J.12, Fussy Z.1, Obornik M.12
1 - Biology Centre CAS, Ceske Budejovice, Czech Republic
2 - University of South Bohemia, Ceske Budejovice, Czech Republic
Tetrapyrroles are organic compounds essential for life. Organisms are either synthesizing tetra-pyrroles or they have to obtain them from their environment, host or prey. We showed that the composition of the biosynthetic pathway is shaped by passed endosymbiotic evens in eukaryotes. We map the pathway in phototrophic eukaryotes, particularly in algae with secondary or other advanced plastids, by investigating origins of involved enzymes and predicting their location in the cell of the euglenophyte Euglena gracillis, the chlorarachniophyte Bigelowiella natans, the cryptophyte Guillardia theta, the dinoflagellate with green secondary plastid Lepidodinium chlorophorum, and dinoflagellates bearing diatom endosymbiont (also called "dinotoms") — Glenodinium foliaceum, Kryptoperidinum foliaceum and Durinskia baltica. Chlorarachniophytes and euglenophytes still possess two independently operating tetrapyrrole pathways with the first common precursor S-aminolevulinic acid synthesized either by the C4 pathway in two steps using the mitochondrially located ALA synthase (ALAS), or by the plastid located C5 pathway by consecutive enzymes glutamyl-tRNA reductase (GTR) and glutamate-1-semiladehyde 2,1 aminomutase (GSA-AT). We propose that such arrangement of the pathway was ancestral for all
