CC BY
31
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
