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36 • "PROTIST—2016
associated with a short cytoplasmic outgrowth and the same was shown for all of Luffisphaera spp., studied for that matter. All organells, described for Luffisphaera were found in Belonocystis and shown to have almost identical organization. Both have tubular mitochondrial cristae and vacuoles associated with stacks of rough endoplasmic reticulum cisternae and neither of them was shown to have kinetosomes. B. marina was the first record of marine species for Belonocystis, which again put it closer to Luffisphaera, initially recorded in marine and freshwater habitats. It's possible that the subsequent study of Luffisphaera and extra Belonocystis isolates in future may lead to a fusion of both or to transfer some species from one genus to another. Study was supported with RFBR grants 15-04-18101_a, 15-29-02749-ofi_m.
HIGH ARCTIC BENTHIC FORAMINIFE-RANS DURING THE POLAR NIGHT: DORMANCY OR ACTIVE FEEDING? Knyazeva O., Korsun S.
Dept Invertebrate Zool, Biol Faculty, St-Petersburg
Univ, Russia
s_korsun@mail.ru
Benthic foraminiferans are the vast meiobenthic group of protists widely represented in all marine habitats including the high Arctic. Although some foraminifera species are known to feed on bacteria, the majority of these protists keep to an algal diet, preying on diatoms and dinofllagelates. Some species are also capable of capturing prey chloroplasts and maintaining them functionally active, thus performing kleptoplasty, which also results in a change of the host cytoplasm coloration. Given the seasonal transitions to long periods of darkness performed in high latitudes and leading to scarceness of primary production, one would expect foraminiferans to face absence of prey algae and starvation, the latter resulting in either death or dormancy of the most part of population. Nevertheless, our results contradict such assumptions. In January 2015 and 2016, during the Marine Night cruise with RV Helmer Hanssen, we collected live specimens in the Kongfjorden area, Svalbard. All major species (Nonionella labradorica, Islandiella helenae, Cassidulina reniforme, Elphidium excavatum, Elphidium bartletti) had brightly species-specifically colored cytoplasm implying they did not starve but had access to algal food. Transmission electron microscopy revealed that all specimens had well-developed mitochondria, Golgi apparatus and endoplasmic reticulum, therefore being meta-bolically active throughout the winter season. Moreover, some foraminiferans possessed intact
chloroplasts within cytoplasm. These results strongly indicate that high Arctic benthic foraminifera are not dormant during the polar night, and they access algal diet.
Supported by Research Council of Norway grant 226417/E10 and RFBR grant 14-04-93083.
TIM17 FAMILY PROTEIN IN THE MITO-SOMES OF GIARDIAINTESTINALIS Kolisko M.1, Martincova E.2, Voleman L.2, Roger A.J.3 4, Dolezal P.2
1 - Canadian Institute for Advanced Research, Department ofBotany, University ofBritish Columbia, Vancouver, Canada
2 - 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
3 - Centre forComparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
4 - Program in Integrated Microbial Biodiversity, Canadian Institute for Advanced Research, Halifax, Nova Scotia, Canada lubos.voleman@gmail.com
Protein transport across the mitochondrial membranes is mediated by the TIM, TOM and SAM complexes. These complexes are common to all supergroups of eukaryotes suggesting that they were already present in the last eukaryotic common ancestor. However, mitochondria-related organelles of Giardia intestinalis known as mitosomes were thought to lack both the SAM (a beta barrel assembly complex in the outer membrane) and the TIM (the translocase of the inner membranes) their membranes. The question was, how proteins pass the inner mitosomal membrane. Here, we present the identification of Tim17 family protein in giardia mitosomes, which represents a core channel forming subunit of the TIM complex. The bioinformatic identification of this highly diverged subunit was only possible by including newly obtained orthologous metamonad sequences in the sequence profiles. We demonstrate that giardia Tim17 is specifically targeted to mitosomes, where it interacts with other proteins involved in the protein transport and the iron-sulfur cluster assembly.
HETEROTROPHIC NANOFLAGELLATES IN THE PLANKTON OF LAPTEV SEA Kopylov A.I.1, Zabotkina E.A.1, Kosolapova N.G.1, Romanenko A.V.1, Sazhin A.F.2 1 - Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences, Russia
