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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 m.leger@dal.ca
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 duckhyunlhee@gmail.com
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.
omatos@ihmt.unl.pt
The main goal ofthis study is to address the functional
