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presence of molecular signals of eukaryotic groups including Dinophyta, Stramenopiles, Ciliophora and Fungi. The relative proportions of these major groups were different among the three sites, with NYS and SYS were more similar to each other than to YR. Here we will briefly report the community composition and structure of microbial eukaryotes, and hope to link these signals in the near future with geochemical information to reflect the ecosystem conditions and changes of the north China Seas during the past thousands of years.
FEEDING SELECTION OF MIX-TROPHIC FLAGELLATE, POTERIOOCHROMONAS MALHAMENSIS, ON THE GREEN ALGAE OF CHLORELLA
Gong Yingchun12, Ma Mingyang12, Wei Chaojun12
1 - Center for Microalgal Biotechnology and Biofuels, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
2 - Key Laboratory for Algal Biology, Institute of Hydrobiology, Chinese Academy ofSciences, Wuhan, China
Poterioochromonas is a very common mix-trophic flagellate in most freshwater environments, which can grow in autotrophic way or by feeding bacteria and other protists. Several species of algae have been reported to be the prey of Poterioochromonas, however little is known about whether and how Poterioochromonas has feeding selection on the prey. In this study, two strains of Chlorella sorokiniana showed significantly different defense ability on the grazing of Poterioochromonas. Both morphological and molecular approaches were combined to discover the factors which contributed to the defense ability on grazing. Light microscopic showed that the two strains didn't have much difference on the cell size and shape, however transmission electron microscopic observations and protein composition analysis indicated that the two strains have different cell wall composition and biochemical composition. Our research suggested that probably some protein in the cell wall of Chlorella played an important way to defense the grazing of Poterioochromonas.
THE GENOME OF UNDARIA PINNATIFIDA
AND UNDARIA PETERSENIANA: INSIGHTS
INTO KELP EVOLUTION
Graf L.1, Yang J.H.1, Lee J.M.1, Boo S.M.2, Yoon
H.S.1
1 - Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Korea
2 - Department ofBiology, Chungnam National Uni-
versity, Daejeon 34134, Korea [email protected]
The genus Undaria consists of large multicellular brown algal kelps. In Korea, U. pinnatifida and U. peterseniana are extensively cultivated (~500.000 tons/year) for human food and commercial extracts. Although phylogenetically related, the two species are ecologically distinct and have strikingly different distributions, morphologies and reproductive strategies. Spores of U. pinnatifida are produced in a specialized sporophyll that is localized on the lower part ofthe stipe whereas in U. peterseniana the sporophylls differentiate directly from the blades, which is a process similar to that for species of the genus Saccharina, another common kelp genus. We produced draft genomes for U. peterseniana and U. pinnatifida; with the previously released draft genome of Saccharina japonica, they represent the only genomic resources available for the kelps. We examined gene content, genome organization, and transposable elements dynamics. We will discuss the genomic differences between U. pinnatifida and U. peterseniana, and we will describe new insights into their evolutionary history; most notably, we will comment on the origin ofmulticellularity in the brown algae. Finally, the genome sequences for the two edible algae should be a new, major resource for kelp crop improvement and biotechnology.
NEW GENOMES OF UNICELLULAR HOLO-ZOANS SHED LIGHT ONTO THE ORIGINS OF COMPLEX ANIMAL GENE ARCHITECTURE Grau-Bove X.12, Ruiz-Trillo I.123
1 - Institut deBiologia Evolutiva (UPF-CSIC)
2 - Universitat de Barcelona
3 - Institucio Catalana de Recerca i Estudis Avangats [email protected]
The origin of animal multicellularity is a major event in eukaryotic evolution. Metazoans share many novelties in genome content and structure related to their multicellular lifestyle, like gene families (transcription factors and specific signaling pathways) and regulatory mechanisms (alternative splicing or enhancer-enabled introns). Since many of these traits predate metazoans, the study of their unicellular holozoan relatives is key to understand animal origins. We analyse the evolution of gene architecture using new ichthyosporean genomes, choanoflagellates and the filasterean Capsaspora owczarzaki, plus 40 other eukaryote genomes. This two-fold analysis focuses on the evolution of 1) intron/exon structure and 2) protein domain architectural rearrangements (which define gene families' function and diversification). Animals
24 • "PROTIST—2016
have complex gene architectures, intron-rich and with high protein domain diversity. We find that such enrichments occur in differentially-timed innovation bursts. For example, the most important premetazoan intronization event occurred in the last common ancestor of choanoflagellates and animals (>80% homologous introns when compared to the urme-tazoan). Conversely, animal-specific protein domain arrangements often appear before, in the urholozoan (~12% ofnovel arrangements, compared to frequent contractions in later-branching lineages). Our results support a scenario of sudden innovation processes within holozoans followed by gradual simplifications in extant protistan lineages, while Metazoa retain most novelties and develop more of their own. This is observed for both intronization and protein rearrangements. Yet, these aspects of gene architecture are decoupled in time and mechanis-tics: non-coding and coding gene elements are under different evolutionary pressures, and innovation bursts are identified in different ancestors.
THE ROLE OF CAEDIBACTER-INDUCED KILLER TRAITS IN PARAMECIUM INTER-STRAIN AND INTERSPECIES COMPETITION Grevtseva I.1, Nekrasova I.1, Lanzoni O.2, Lebedeva N.3, Petroni G.2, Potekhin A.1
1 - Faculty of Biology, St Petersburg State University, Saint Petersburg, Russia
2 - Department of Biology, University of Pisa, Pisa, Italy
3 - Centre of Core Facilities "Culture Collections of Microorganisms", St Petersburg State University, Saint Petersburg, Russia [email protected]
Some species of Paramecium (Ciliophora) present killer traits when inhabited by bacterial endosym-bionts belonging to the genus Caedibacter. These bacteria are occasionally released by killer strains to the environment, get engulfed by other paramecia, and secrete a not yet characterized toxin, which kills symbiont-free ciliates. We studied three Paramecium biaurelia strains bearing cytoplasmic symbionts Caedibacter caryophilus. The killer strains originated from St Petersburg region, Russia, and from Sicily, Italy. All strains were characterized by different rate and dynamics ofkiller effect manifestation; sensitive paramecia displayed various lethal and malfunction symptoms. The killer cells were resistant to their own killer trait even after antibiotic-induced removal of symbionts, thus allowing to assume that resistance is genetically determined. Also killer strains appeared to be relatively reciprocally resistant for the other killers. We made a series of tests to reveal resistance or sensibility to killer effects for a number of strains
representing several Paramecium species. The results indicated that the strains of the P. aurelia species complex and P. caudatum were generally rather sensitive, while the strains ofphylogenetically distant species were almost always resistant. Thus, Caedibacter might give a significant advantage for the host, providing it with a powerful weapon for competition with uninfected paramecia normally present in the same environment. Several strains of symbiont-free P. biaurelia also appeared to be resistant, thus allowing to speculate that this species might be genetically adapted to be the host of C. caryophilus. Supported by RFBR 16-04-01195.
HIDDEN DIVERSITY IN MALLOMONAS MATVIENKOAE SPECIES COMPLEX Gusev E.S.1, Kapustin D.A.1, Doan Nhu-Hai2, Nguyen Ngoc-Lam2
1 - Papanin's Institute for Biology of Inland Waters Russian Academy of Sciences, Russia, 152742 Yaroslavl, Nekouz., Borok
2 - Institute of Oceanography, Viet Nam Academy of Science and Technology, 01 Cau Da, Vinh Nguyen, Nha Trang, Viet Nam
Mallomonas matvienkoae B. Asmund & Kristi-ansen is considered as a widespread taxon (Kristi-ansen & Preisig 2007) from the order Synurales, class Chrysophyceae. This species have been described from Ukraine under the name Mallomonopsis ellip-tica Matv. (Matvienko 1941) and later redescribed and transferred into the genus Mallomonas (Asmund & Kristiansen 1986). Mallomonas matvienkoae is a polymorphic species; it includes five varieties and forms. An investigation of the clonal cultures of M. matvienkoae representing populations from subtropics resulted in descriptions of three new species using both morphological features and molecular data (Jo et al. 2013). The authors also described a fossil species of this group. Our studies of this species complex in the tropics (Vietnam and Indonesia) revealed at least four new taxa for science confirmed by molecular methods. One of them has been already described as M. paragrandis E.S. Gusev (2015). Additionally, five new morphotypes ofscales have been found which can be considered as new species for science. Three taxa, recently described by Jo et al. (2013), were also found in Vietnam (Mallomonas hexareticulata, M. sorohexareticulata and M. pseudomatvienkoae). Thus, Mallomonas matvienkoae species complex is a rather diverse group of pseudocryptic taxa, which needs further studies using polyphasic approach. This study was supported by RFBR grants 15-04-04181 and 1634-60099.
