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74 • "PROTIST—2016
PARATRYPANOSOMA, THE MOST BASAL BRANCH AND ANOTHER MODEL SPECIES AMONG TRYPANOSOMATIDS Skalicky T.1, Dobakova E.1, Flegontov P.123, Votypka J.14, Yurchenko V.12, Lukes J.156
1 - Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Ceske Budejovice, Czech Republic
2 - Faculty ofScience, University ofOstrava, Ostrava, Czech Republic
3 - A.A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russian Federation
4 - Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic
5 - Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
6 - Canadian Institute for Advanced Research, Toronto, Canada
pavel@paru.cas.cz
Dozens of trypanosomatids (Trypanosomatida, Kinetoplastea, Euglenozoa) have been studied from the genomics perspective, however there is a strong bias towards species pathogenic for mammals, while numerous monoxenous (single-host) parasites of insects have been neglected. This year we have published the first high-quality genome of a monoxenous insect trypanosomatid, Leptomonas pyrrhocoris. Here we present a comprehensive study of another probably monoxenous species, Paratrypanosoma confusum, a cosmopolitan parasite of Culex mosquitoes. This species forms the most basal branch of the trypanosomatid clade. Paratrypanosoma produces three distinct forms in axenic culture: swimming promastigotes, immobile amastigotes, and sessile cells, firmly attached to the surface. Using scanning and transmission electron microscopy, still and video light microscopy, and fluorescent antibodies we have fully characterized the ultrasctructure and behavior ofthe unique sessile morphotype. Formation of transient sessile stage is stimulated by basic pH and by biopterin, and sessile cells are attached to the surface with the help of an extracellular 'glue' resistant to all enzymatic treatments. We have performed differential RNAseq analysis of the promastigote and sessile cells, and sequenced the genome of P. confusum using Illumina MiSeq reads of250 nt (a paired-end and a mate pair library). A draft genome assembly has been produced with the following statistics: scaffold N50 of 458 kbp, 189 scaffolds, 31.6 Mbp genome size, ~8,800 genes. Using the Paratrypanosoma genome as an outgroup, we have illuminated patterns of gene family gains and losses in an important genus Trypanosoma and in trypanosomatids as a whole.
POTENTIALLY TOXIC MARINE DINOFLA-GELLATES: CELL AND MOLECULAR ADAPTATIONS TO STRESS Skarlato S.O.
Institute ofCytology RAS, St. Petersburg, Russia s_skarlato@yahoo.com
Potentially toxic marine planktonic dinoflagellates represent an ecologically important group of single-cell eukaryotes which show pronounced physiological adaptability to various types of environmental stress. These protists respond to harsh conditions by activation of their defensive mechanisms, which can differ from those of large multicellular forms. The dinoflagellates Prorocentrum minimum (or P. cordatum) in the Baltic Sea have recently become good model objects in the environmental and cell biology studies of unicellular eukaryotes. The goal of this paper is to demonstrate what cell and molecular mechanisms underpin the fast and effective adaptations of these protists in the brackishwater habitats. We focused on cell metabolism, ion channel research, and on the effects of different levels of salinity and elevated temperature on cell mortality, cell cycle pattern, RNA synthesis, and DNA replication in P. minimum. It appears that P. minimum can utilize urea as a source of organic nitrogen but also as a source of carbon. Moreover, urea inhibits assimilation of nitrate (the "classic" source of nitrogen) and can be the preferable substrate in the coastal brackish waters. Dinoflagellates show elevated biosynthetic activity and low cell-death level at critical salinity 5-8 %c. We infer that this potentially toxic, bloom forming dinoflagellate species displays great colonizing ability across new ecosystems likely due to high physiological plasticity and pronounced adaptation potential at different levels ofbiological organization, from molecules and cells to populations. Funded by the Russian Science Foundation, project 16-14-10116.
GENOMIC ANALYSIS OF NEPHROMYCES SHEDS INTO AN ENIGMATIC SYMBIOTIC SYSTEM BETWEEN A TUNICATE AND A DIVERGENT APICOMPLEXAN Slamovits Claudio12, Muñoz-Gómez S.12, Kennedy K.1, Paight C.3, Lane C.3
1 - Dalhousie University
2 - Canadian Institute for Advanced Research
3 - University of Rhode Island cslamo@dal.ca
Nephromyces is a divergent apicomplexan that lives as an endosymbiont in the renal sac of mol-gulid tunicates. The nature of Nephromyces as an apicomplexan remained enigmatic for long
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time, mostly due to: (i) its peculiar habitat, (ii) the presence of cytoplasmic bacterial endosymbionts, (iii) a complex life-cycle with unusual morphologies, and (iv) a presumably mutualistic association with its animal host. Moreover, several lines of evidence suggest that the renal sac of an individual tunicate host harbors a complex community of diverse Nephromyces lineages: the multiple-infection hypothesis. We decided to further investigate this hypothesis and elucidate the phylogenetic position of Nephromyces within Apicomplexa by using deep sequencing of renal sacs in order to better understand the developmental dynamics of this symbiosis. Our initial analyses revealed the presence of eleven apicoplast genomes in one single renal sac. Surprisingly, there was considerable sequence divergence among the apicoplast genomes, although their gene content and order was highly conserved. We then used the phylogenetic information contained within 27 apicoplast proteins to infer Nephromyces' phylogenetic placement within Apicomplexa. These preliminary results support the idea that molgulid renal sacs are complex ecosystems inhabited by a diverse community of different Nephromyces lineages. In addition, we clarified the phylogenetic position of Nephromyces as sister to 'core' apicomplexans (Hematozoa+Coccidia), and highlighted the significant intra-clade divergence among these apicoplasts. Future efforts will focus on elucidating the metabolic contribution of each partner to the dynamics of this complex symbiotic system.
PHYLOGENY, DIVERSITY AND EVOLUTION OF AMOEBOZOA: NEW FINDINGS AND NEW PROBLEMS Smirnov Alexey
DepartmentofInvertebrate Zoology, Faculty ofBiology, St. Petersburg State University, St. Petersburg, Russia alexey.smirnov@spbu.ru
Amoebozoa is a major group of protists that unifies naked and testate lobose amoebae, varioseans, slime molds and pelobionts. The diversity and systematics of some groups, like slime molds and testate amoebae, possessing stable morphological characters - fruiting bodies or tests - was relatively well studied, also some evolutionary traits derived from morphology were further disproved by molecular phylogeny. In contrast, naked amoeboid protists with no constant shape remain relatively poorly known, molecular phylogeny nearly entirely rearranged earlier views on their evolutionary relationships. SSU-based phylogeny shows that naked amoebae belong to three different amoebozoan lineages and the most of organisms formerly known
as protostelids are dispersed among different groups. The basic finding was the split of naked amoebae in two lineages, named Tubulinea and Discosea and the fact that testate lobose amoebae form just a single branch within Tubulinea. The basal branching of Amoebozoa could not be properly resolved with SSU trees. Multigene data help to clarify many essential questions, e.g. they show that Discosea does not appear to be a monophyletic group. However, with the increment of taxon sampling multigene trees seem to experience the same problems and artifacts as SSU trees did. Recent studies of extreme and exotic habitats revealed a number of new species, especially among the smallest amoebozoans, some were found to be key taxa for rooting Amoebozoan tree. Genbank contains numerous unnamed sequences belonging to new amoebozoan lineages. This indicates that environmental diversity of Amoebozoa is still in much unexplored. Supported with RSF grant 14-14-00474.
TRANSCRIPTOME ANALYSIS OF NAEGLE-RIA FOWLERICYSTS AND TROPHOZOTIES BY NEXT-GENERATION SEQUECING Sohn Hae-Jin1, Seong Gi-Sang1, Kang Heekyoung1, Jung Suk-Yul2, Shin Ho-Joon1, Kim Jong-Hyun3
1 - DepartmentofMicrobiology, Ajou University School of Medicine, Republic of Korea
2 - Department of Biomedical Laboratory Science, Molecular Diagnostics Research Institute, Namseoul University, Republic of Korea
3 - Institute ofAnimalMedicine, College of Veterinary Medicine, GyeongsangNational University, Republic of Korea
hj35good@ajou.ac.kr
Naegleria fowleri, ubiquitous pathogenic amoeba causing the fatal primary amoebic meningo-encephalitis (PAM) in experimental animal and humans, is predominantly living in the ponds, lakes, rivers and swimming pools. N. fowelri trophozoites are encysted under unfavorable conditions such as cold temperature, starvation and desiccation. However, the information in differential expression genes between cysts and trophozoites of N. fowelri is very limited. In this study, RNA-sequencing libraries from N. fowleri cysts and trophozoites were investigated by Next-Generation Sequencing (NGS) analysis. In the NGS database, the assembly procedure resulted in mean full length of 11, 254 nucleotides in total 42,220 transcript contigs and 37.21 % of C+G contents. RNA sequencing indicated that upregulated 143 genes in cysts showed 2 folds expression in comparison with trophozoites and 163 genes were downregulated. These genes were found to participate in Kyoto Encyclopedia
