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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
42 • "PROTIST—2016
roles of PDI on Toxoplasma gondii-host interplay, in the context of acute/chronic infection, and evaluating their usefulness as drug-targets using antihuman PDI commercial MAbs. The potential cross-reactions of PDI anti-human MAbs with T. gondii, confirming their usefulness for immunolocalization of PDI not only in human fibroblasts (HFF) target cells, but also in Toxoplasma tachyzoites/cysts were verified. In order to validate this hypothesis a bioinformatics analysis was conducted in the Toxoplasma genome database to search for homologous regions: of the antigens' complete amino acid sequence used in the manufacturing processes of the MAbs utilized in this study; and/or of their more predicted immunogenic regions in case of antigens with longer sequences. Confirmation was obtained by reverse search on human genome for the predicted T. gondii antigens/peptides sequences. Results from indirect immunolabeling assays using immunofluorescence techniques with antihuman PDI MAbs: PDI, PDIA3(ErP57), PDIA6, Calnexin(CNX), glucose-regulated proteins/immu-noglobulin heavy-chain binding protein (GRP78/ BiP) and GRP94 suggest both cross-reaction with target cell-lines and Toxoplasma, being suitable for their profile identification and to evaluate PDI usefulness as a drug-target against T. gondii infection. Different patterns of immunolabeling were observed in Toxoplasma infected and non-infected HFF cells according to the MAb used. The functional confirmation of the characterized PDI involved in the host-pathogen interaction, in the presence of PDI inhibitors, is in progress. Further analyses will be performed by RNA silencing to get complementary evidence of these specific proteins in Toxoplasma-host interactions. Acknowledgments: Supported by FCT ref:VIH/ SAU/0019/2011.
ANALYSIS OF THREE SINGLE-CELL AMPLIFIED GENOMES OF THE CHOANO-FLAGELLATE MONOSIGA BREVICOLLIS REVEALS SINGLE-CELL GENOMICS AS A LIMITED APPROACH FOR EVOLUTIONARY PURPOSES
Lopez-Escardo D. \ Ruiz-Trillo I.12
1 - Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Passeig Maritim de la Barceloneta 37-49, 08003 Barcelona, Catalonia, Spain
2 - Institucio Catalana de Recerca i Estudis Avangats (ICREA), Barcelona, Catalonia, Spain [email protected]
Environmental metabarcoding data is providing a new view of the real protist diversity. This new diversity often occupies key phylogenetic positions
which can led to important insights in the evolution of different eukaryotic lineages. This is the case of the Opisthokonta, in which the identification of new unicellular lineages close to animals has the potential to improve our understanding of the transition towards animal multicellularity. However, isolating these new organisms is a challenge. Instead, single-cell genomics (SCG) seems a prominsing approach to obtain directly the genomes from the environment. However, SCG technologies, which have mainly been employed in prokaryotes, are affected by important biases, specially during the whole genome amplification step. The potential of SGC for eukaryotes remains unclear. To test the potential of this technique for evolutionary studies in eukaryotes, we here analyze three environmental single amplified genomes (SAGs) from the choanoflagellate Monosiga brevicollis, whose genome is already sequenced. We show the genome recovery obtained from our SAGs was low (between 30-5%, around 3,684 out of 9,175 genes). Interestingly, the percentatge of pylogenomic markers that our SAGs contains is good (almost 100% for some datasets). We also explored different techniques to improve the quality and the recovery of the assemblies obtained. We found that genome recovery increased up to 48% by pooling the data from the three different SAGs. Current SCG technologies seem a limited approach for adressing some questions but has the potential to provide enough data for phylogenomic analyses.
DIPLONEMIDS - NEW KIDS ON THE BLOCK Lukes Julius12, Flegontova Olga12, Flegontov Pavel123, Faktorovâ Drahomira12, Kaur Binny-preet12, Votypka Jan124, Tashyreva Dana12, Yabuki Akinori5, Malviya Shruti6, de Vargas Colomban78, Bowler Chris6, Burger Gertraud9, Horâk Ales12
1 - Institute of Parasitology, Biology Centre, Czech Academy of Sciences
2 - Faculty of Science, University of South Bohemia, Ceské Budëjovice
3 - Faculty ofScience, University ofOstrava, Ostrava, Czech Republic
4 - Faculty of Science, Charles University, Prague, Czech Republic
5 - Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan
6 - Ecole Normale Supérieure, PSL Research University, Institut de Biologie de l'Ecole Normale Supérieure (IBENS), Paris, France
7 - Station Biologique de Roscojf, Roscoff, France
8 - Sorbonne Universités, Paris, France
9 - Université de Montréal, Montreal, Canada [email protected].
