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Protistology ■ 23
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
springgong@ihb.ac.cn
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 louis.graf@gmail.com
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 xavier.graubove@gmail.com
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
