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Protistology ■ 87
organism, which assemble Fe-S clusters in the cytosol by concerted action of SUF and CIA pathways.
SYNCHRONIZED AND ER-DEPENDENT DYNAMICS OF MITOSOMES Voleman L.1, Najdrova V.1, Astvaldsson A.2, Tumova P.3, Einarsson E.2, Svindrych Z.4, Hagen G.M.4, Tachezy J.1, Svard S.G.2, Dolezal P.1
1 - BIOCEV— Biotechnology andBiomedicine Center of the Academy of Sciences and Charles University in Vestec and Department of Parasitology, Faculty of Science, Charles University in Prague, Czech Republic
2 - Department ofCell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden
3 - Department of Tropical Medicine, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic
4 - Institute of Cellular Biology and Pathology, First Faculty of Medicine, Charles University in Prague, Czech Republic [email protected]
Mitosomes are the smallest evolutionary forms of mitochondria that evolved in eukaryotes adapted to anaerobic environments. While abandoning many attributes of the aerobic mitochondria such as the genome, respiration and the cristae, mitosomes have retained the double membrane and the bare bones of the pathways for the protein import and the synthesis ofthe iron-sulfur clusters. Here, we studied the dynamics of the mitosomes in the parasitic protist Giardia intestinalis, which belongs to one of five supergroups of eukaryotes known as Excavata. We found that mitosomes are extremely steady organelles during the interphase undergoing neither the fission nor the fusion during the interphase, thus being highly prone to become heterogeneous. Surprisingly, the mitosomal division is restricted to mitosis, when both central and peripheral organelles divide in a synchronized manner. The mitosomes also divide during the encystation of the parasite, thus preconfigure the cyst for the rapid excystation in a new host. Interestingly, the division involves the association of the mitosomes with the endoplasmic reticulum, a relationship typical for the mitochondria of Opisthokonta. While several such tethering mechanisms, which enable lipid transfer between the organelles, have been described for Opisthokonta, none of these have been shown to function in other eukaryotic supergroups including Excavata. However, we were able to show that lipid enzyme long chain acyl-CoA synthetase 4 is distributed to the mitosome-ER interface.
MORPHOLOGICAL AND MOLECULAR INVESTIGATION OF MARINE PARAMOEBI-DAE (AMOEBOZOA, DACTYLOPODIDA) Volkova E.N., Kudryavtsev A.A. Saint Petersburg State University, Russia [email protected]
We present a revision of marine dactylopodid amoebae containing an intracellular eukaryotic symbiont traditionally called 'parasome', and currently known as 'Perkinsela-like organism' (PLO) related to Kinetoplastida. This group traditionally consists of two genera: Paramoeba Schaudinn, 1896 and Neoparamoeba Page, 1987 which differ in their cell coat structure; the former being covered with scales, while the latter, with the thin, scaleless glycocalyx. The third PLO-containing genus, Janickina Chatton, 1953 has no clear taxonomic affinities yet, as no molecular data are available for its members. We present the results of investigation of the biodiversity and phylogenetic relationships within the genera Paramoeba and Neoparamoeba based on 15 marine and brackish water strains isolated from a broad range ofhabitats. The conclusions are based on morphological, ultrastructural and molecular evidence. The data obtained allow us to conclude that (1) Morpho-species of Paramoeba and Neoparamoeba show considerable levels of intragenomic and intraspecies variability based on the SSU rDNA and ITS region sequences; (2) A detailed study combining analysis of light-microscopic data, ultrastructure and molecular evidence is necessary in most of cases to discriminate species within this group; (3) The cell coats of Paramoeba/Neoparamoeba clade have evolved from the scale-bearing ancestral taxa through several independent scale losses in various lineages of this clade. We also present novel data that contribute to further understanding of the co-evolution of amoebae and their intracellular symbionts.
Partially supported by the RFBR grant 15-29-02749; the study utilized the equipment of the core facility centers of St. Petersburg State University.
CILIATES AS BIOINDICATORS OF MARINE WATER QUALITY Warren A.1, Xu H.2
1 - Department of Life Sciences, Natural History Museum, London, UK
2 - Laboratory ofMicrobialEcology, Ocean University of China, Qingdao, China [email protected]
Although protists, and especially ciliates, have long
