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40 • "PROTIST—2016
pathogenic forms associated with damaged corals undergoing disease conditions, such as Brown Band disease. These altered communities are characterized by rapid tissue breakdown in hard corals, coupled with high levels of dissolved organic matter. Samples were taken by direct capture, observed with phase contrast and epifluorescence microscopy, recorded by video and photomicrography, and fixed for later identification and genomic studies. The relative abundance of diatoms/flagellates/ ciliates appears to show a higher proportion of photosynthetic species as compared to previous observations. Brown Band ciliates were not found on the corals, in the sediments, on algal surfaces, or in the plankton prior to bleaching in late January, posing the question oftheir location when not acting as opportunistic pathogens.
"CANDIDATUS MEGAIRA": AN EMERGING GENUS OF BACTERIAL ENDOSYMBIONTS WIDESPREAD IN CILIATES AND OTHER PROTISTS
Lanzoni O.1, Shaidullina A.2, Sabaneyeva E.2, Castelli M.1,3, Lebedeva N.4, Potekhin A.2, Petroni G.1
1 - Department of Biology, University of Pisa, Pisa, Italy
2 - Faculty ofBiology, St. Petersburg State University, Saint Petersburg, Russia
3 - Department of Veterinary Medicine, University of Milan, Milan, Italy
4 - Centre of Core Facilities "Culture Collections of Microorganisms", St Petersburg State University, Saint Petersburg, Russia [email protected]
" Candidatus Megaira" (Rickettsiaceae) is a recently described genus of obligate intracellular bacteria, which are phylogenetically closely related to the pathogen Rickettsia. Sequences representatives of genus " Candidatus Megaira" can be split in at least 3-4 species level sub-clades. These sequences have been found in association to evolutionary far related host lineages (e.g. unicellular and multicellular algae, corals and hydras). The type species of the genus, "Candidatus Megaira polyxenophila", has been found in several ciliates as well as in other protists. In ciliates, " Candidatus Megaira polyxenophila" can infect different cell compartments (macronucleus and cytoplasm) according to the host species. Herein, we provide the characterization of a second "Candidatus Megaira" species inhabiting the cytoplasm ofthe green ciliate Paramecium bursaria. Within the same host cell, this novel " Candidatus Megaira" presents polymorphic features such as the association with endosymbiotic algae, or the possible
presence offlagellum at some stage ofthe life-cycle. Moreover, we performed several trans-infection experiments using different species of newly characterized " Candidatus Megaira" in order to understand how representatives of this genus can be spread in the aquatic environment and how they influence the host fitness within the same ciliate population. We also investigated the interaction between " Candidatus Megaira" and other symbiotic bacteria already inhabiting or invading the same host cell. All together, our findings highlight the necessity of a better understanding of the life-cycles of this widespread, but poorly investigated, endosymbiont.
THE GENOMIC STUDY OF AGAR PRODUCING RED ALGA GRACILARIOPSIS CHORDA Lee J.M.1, Yang E.C.2, Graf L.1, Yoon H.S.1
1 - Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Korea
2 - Marine Ecosystem Research Division, Korea Institute of Ocean Science & Technology, Ansan, 15627, Korea
Red algae (Rhodophyta) played an important role in the evolution of photosynthetic organisms as plastid donor(s) in chlorophyll-c containing algae including cryptophytes, haptophytes, stramenopiles, and alveolates. Most red algal species are important components in marine ecosystems, serving as a shelter for diverse marine organisms and contributing as primary producers. Many red algal species are heavily cultivating as food and industrial purposes such as agar and carrageenan production. Despite of these importances, only several red algal genomes have been reported among more than 7,000 species. From the major multicellular red algal group of theFlorideophyceae, only one genome was fully sequenced to date. To fill the gap of our understanding on red algae, here we analyzed a new genome of the multicellular red algal species Gracilariopsis chorda, which is one of major cultivar as food and agar production in Korea. Using the long-read single molecule sequencing (PacBio) platform, we completed whole-genome of 89.6 Mbp (49% GC content, 1,098 contigs) that encodes a total of 9,992 predicted proteins. We discuss the interesting story of genome reduction/expansion and gene duplication in red algal genomes at this meeting.
AN ANCESTRAL BACTERIAL DIVISION SYSTEM IS WIDESPREAD IN EUKARYOTIC MITOCHONDRIA
Leger M.M.1, Petru M.2, Zarsky V.2, Eme L.1, Vlcek C.3, Harding T.1, Lang B.F.4, Elias M.5, Dolezal P.2,
Protistology ■ 41
Roger A.J.1
1 - Dept. of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Canada
2 - BIOCEV Group, Department of Parasitology, Faculty of Science, Charles University in Prague
3 - Laboratory of Genomics and Bioinformatics, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic
4 - Robert Cedergren Centre for Bioinformatics and Genomics, Département de Biochimie, Université de Montréal, Montréal, Canada
5 - Department of Biology and Ecology, Faculty of Science, University of Ostrava, Czech Republic [email protected]
Bacterial division initiates at the site of a contractile Z-ring composed ofpolymerized FtsZ. The location of the Z-ring in the cell is controlled by a system of three mutually antagonistic proteins, MinC, MinD, and MinE. Plastid division is also known to be dependent on homologs of these proteins, derived from the ancestral cyanobacterial endosymbiont that gave rise to plastids. In contrast, the mitochondria of model systems such as Saccharomyces cerevisiae, mammals, and Arabidopsis thaliana seem to have replaced the ancestral alphaproteobacterial Min-based division machinery with host-derived dyna-min-related proteins that form outer contractile rings. By mining transcriptome and genome data, we show that the mitochondrial division system of these model organisms is the exception, rather than the rule, for eukaryotes. We describe endosymbiont-derived, bacterial-like division systems comprising FtsZ and Min proteins in diverse less-studied eukaryote protistan lineages, including jakobid and heterolobosean excavates, a malawimonad, stramenopiles, amoebozoans, a breviate, and an apusomonad. For two of these taxa, the amoebo-zoan Dictyostelium purpureum and the jakobid Stygiella incarcerata, we confirm a mitochondrial localization of these proteins by their heterologous expression in Saccharomyces cerevisiae. The discovery of a proteobacterial-like division system in mitochondria of diverse eukaryotic lineages suggests that it was the ancestral feature of all eukaryotic mitochondria and has been supplanted by a host-derived system multiple times in distinct eukaryote lineages.
DIVERSITY OF PHOTOSYNTHETIC PAU-LINELLA SPECIES INCLUDING A COMPARATIVE PLASTID GENOME ANALYSIS Lhee D.H.1, Yang E.C.2, Kim J.I.3, Kim S.4, Park M.G.4, Andersen R.A.5, Yoon H.S.1 1 - Department of Biological Science, Sungkyunkwan University, Suwon 16419, Republic of Korea
2 - Marine Ecosystem Research Division, Korea Institute of Ocean Sciences & Technology, Ansan 15627, Republic of Korea
3 - Department of Biology, Chungnam National University, Daejeon 34134, Republic of Korea
4 - Department ofOceanography, Chonnam National University, Gwangju 61186, Republic of Korea
5 - Friday Harbor Laboratories, University of Washington, WA, 98250, USA [email protected]
The thecate filose amoeba Paulinella chromatophora is a good model organism for understanding plastid organellogenesis because its plastid was derived from a Synechococcus-Cyanobium type of alpha-cyanobacterium. Recent studies have shown species-level of divergence after the acquisition of the organelle; however, a full investigation has not been conducted for the photosynthetic species. We surveyed the biodiversity ofthis interesting alga using samples collected from around the world. Using four gene markers (18S rRNA, 16S rRNA, dnaKl, psaL), two distinct lineages with high genetic variation were identified, including one new species candidate (i.e., P. microporus). In addition, the chromatophore genome was fully sequenced from P. microporus strain KR01 and the recently reported marine P. longichromatophora. Comparative genomic analysis showed 0.17% of sequence divergence between the Korean strain KR01 and the Japanese strain FK01. Among 1,626 variable sites, the divergence was converged on noncoding regions at a rate seven times higher than for coding regions. The chromatophore genome of P. longichromatophora, when compared to other photosynthetic Paulinella species, showed a higher mutation rate. These results suggest that the diversification of the photosynthetic Paulinella species has occurred at a rapid rate and that the diversification is still ongoing.
ROLE OF PROTEIN DISULFIDE ISOMERASE (PDI) ON TOXOPLASMA-HOST INTERPLAY: IMMUNOLOCALIZATION ASSAYS USING ANTI-HUMAN PDI MONOCLONAL ANTIBODIES (MABS) ON IN VITRO CULTURE SYSTEMS
Lobo Maria Luisa1, Novo Carlos2, Matos Olga1
1 - Medical Parasitology Unit, Group ofOpportunistic Protozoa/HIV and Other Protozoa, Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical (IHMT), Universidade Nova de Lisboa (UNL)
2 - Medical Parasitology Unit, IHMT, UNL, Lisboa, Portugal.
The main goal ofthis study is to address the functional
