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Protistology ■ 11
University of Ostrava, 710 00 Ostrava, Czech Republic
2 - Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 2-15Natsushima, Yokosuka, Kanagawa 237-0061, Japan
3 - Biology Centre, Institute of Parasitology, Czech Academy of Sciences, 370 05 Ceske Budejovice (Budweis), Czech Republic
4 - Faculty of Science, University of South Bohemia, 370 05 Ceske Budejovice (Budweis), Czech Republic
5 - A.A. Kharkevich Institute for Information Transmission Problems, Russian Academy ofSciences, 127 051 Moscow, Russian Federation
6 - Canadian Institute for Advanced Research, Toronto, Ontario M5G1Z8, Canada [email protected]
Diplonemea (Euglenozoa) is an understudied group of heterotrophic flagellates, related to euglenids and kinetoplastids. Diplonemids are abundant in the deep ocean and, surprisingly, represent the most diverse clade of pelagic eukaryotes, according to our metabarcoding data. There are four major clades within diplonemids: i/ clade of 'classic' diplonemids, Diplonema and Rhynchopus; ii/ small clade of Hemistasia; iii/ small clade of environmental sequences (DSPD II, deep-sea pelagic diplonemids II); iv/ large clade of environmental sequences (DSPD I). The DSPD I clade accounts for >97% of diplonemid abundance and diversity in the oceanic plankton, and Hemistasiaphaeocysticola, a recently isolated marine flagellate that feeds on diatoms and dinoflagellates, appears to be the closest relative of DSPD I according to some phylogenetic analyses. It not clear whether H. phaeocysticola is a predator, a parasite, or a scavenger of dead cells. An axenic culture was obtained from H. phaeocysticola growing with Thalassiosira cf. rotula. The genome and transcriptome of H. phaeocysticola were sequenced using 300 and 250 nt paired-end Illumina MiSeq reads, respectively. A draft genome assembly was obtained using CLC Genomics Workbench v.8.1 and has the length of ~260 Mbp and N50 of1.5 kbp. The results suggest that the genome of H. phaeocysticola is similar to that of Diplonema papillatum in size and has a very high repeat content. Additional genome sequencing using PacBio will be performed and the metabolism of H. phaeocysticola will be studied using a transcriptome assembly.
MIXOTROPHIC CILIATES AS SPECIAL ECOLOGICAL GROUP IN WATERBODIES OF CENTRAL AND LOWER VOLGA AND KAMA Bykova S.V.
Institute of ecology of the Volga river basin of RAS [email protected]
In plankton of polytypic waterbodies from Cent-
ral, Lower Volga and Kama 39 species of the mixotrophic ciliates are revealed. Their structure is heterogeneous: there are "epilimnic" aerophylic myxotrophs and microaerophylic or anaerobic myxotrophs. The first group appears in the low trophic state reservoirs; reservoirs with unstable stratification; in the epilimnium of the stratified waterbodies; in acid, colored, with level fluctuation waterbodies. The second group prefers microaerobic and anaerobic conditions of stratified eutrophic and hypertrophic lakes with high sulfides concentration. The absolute maximums of abundance (206540 ind./l) and biomass (7264 mg/m3) of mixotrophs are registered during summer stratification in a highly trophic meromictic pond, and the maximum contribution to biomass - in the small polyhumic lakes (98%).The ciliates' mixotrophic biomass (6,1 g/m3) is comparable with the anoxic phototrophic bacteria biomass (9,6 g/m3) and phytoflagellates (2,6 g / m3) in chemocline and adjacent layers. Their contribution to the overall "phototrophic" component biomass reaches about 37%, while in other waterbodies the total biomass of ciliates several orders of magnitude less than the biomass of other protists and bacteria. The scheme of different mixotrophs species confinement to various waterbodies and ecotopes in gradient of major abiotic factors has been drawn. An inverse relationship between environmental indicators saprobity and mixotrophic ciliates percentage was shown on example of oligo-mesotrophic lake. This can be used when assessing the state of aquatic ecosystems. It was proved that the species composition and the nature of their distribution are determined by specific abiotic and biotic conditions and weakly dependent on the zonal factors.
THE ROLE OF PROTISTS IN THE PLANKTON COMMUNITY OF FRESHWATER LAKE IN THE PERIOD OF ITS EUTROPHICATION Bykova S.V., Umanskaya M.V., Gorbunov M.U., Tarasova N.G., Zharikov V.V., Muchortova O.V. Institute of ecology of the Volga river basin of RAS [email protected]
The Lake Kandry-Kul is one of the largest natural lakes of the Middle Volga basin. It is a popular resting place and therefore experience significant recreation load. From 2010 to 2012 the trophic level ofthe lake has increased from a predominantly oligotrophic to mesotrophic. We studied the following groups ofprotists: ciliates, dinoflagellates, chrysophytes, cryptophytes and euglenids. Their biomass in 2012 compared to 2010 has increased 2.4 times. Their contribution to the total biomass of plankton community and to the to-tal unicellular
12 • "PROTIST—2016
plankton biomass has also increased 1.9 and 1.3 times, respectively. Along with these changes, a redistribution of the total biomass of the plankton community has occured between the pelagic and littoral parts. In the pelagic zone of the lake the increase was most significant, 3.8 times, and in the littoral zone it amounted 1.3 times. The share of protists in the unicellular plankton biomass in the pelagic zone remained unchanged, while in the littoral zone it increased 2.3 times. Protist's contribution into the total plankton biomass in the pelagic zone increased 1.3 times, and in the littoral 3.4 times. These changes were mainly related to the increased role of the cryptophytes, dinoflagellates and ciliates, especially mixotrophic. In the context of eutrophication the most significant correlations of individual groups ofprotists were registered with the concentrations of phosphorus, ammonia nitrogen and chlorophyll a. The influence of environmental factors on the peculiarities ofprotist distribution and ratios of their groups are discussed.
IOTANEMA SPIRALE GEN. ET SP. NOV., A NEW ENDOBIOTIC LINEAGE OF FORNI-CATA WITH STRIKINGLY SIMPLIFIED MORPHOLOGY AND ULTRASTRUCTURE Cepicka I.1, Yubuki N.1, Zadrobilkova E.12
1 - Department of Zoology, Charles University in Prague, Vinicna 7, 128 44 Prague 2, Czech Republic
2 - Centre for Epidemiology and Microbiology, National Institute of Public Health, Srobarova 48, 100 42 Prague, Czech Republic [email protected]
Fornicata is a lineage of excavates living in low oxygen environments and lacking a conventional mitochondrion. Three main morphological/ecological subgroups of Fornicata are recognized: free-living Carpediemonas-like organisms (CLOs) from marine habitats and two parasitic/commensal lineages living in animal hosts, retortamonads and diplomonads. The research of Fornicata centers on evolutionary perspectives such as transition from free-living lifestyle to parasitic one and mitochondrion transformation. Nonetheless, current modest knowledge of the biodiversity of Fornicata limits our ability to draw the whole picture of evolutionary history of this group. The free-living CLOs are particularly important due to the plesiomorphic traits of excavates. In this study, we cultured a novel member of Fornicata, Iotanema spirale gen. et sp. nov., isolated from fresh feces of a gecko. I. spirale exhibits several unique features not seen among fornicates. It possesses a single flagellum and a highly reduced cytoskeletal system with a single microtubular root, two fibers, and
dorsal fan; the excavate ventral groove is missing. SSU rRNA gene analyses demonstrated that I. spirale branches as a sister lineage to the free-living CLO Hicanonectes teleskopos and its relatives, which means that it represents the third known endobiotic lineage of Fornicata.
SPATIOTEMPORAL DISTRIBUTION OF SPECIES DIVERSITYAND COMMUNITY STRUCTURE OF CILIATES IN INTERTIDAL SANDY SEDIMENTS OF HUOKUN'AO BEACH, NANJI ISLANDS (EAST CHINA SEA, CHINA) Chen X.1, Chen W.2, Cai H.2, Xu K.1
1 - Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
2 - Nanji Islands National Marine Nature Reserve Administration, Pingyang 325401, China [email protected]
In intertidal sediments, ciliates are a highly diverse and quantitatively dominant group, whose community structure, in some sense, may reflect the condition of environmental quality. We investigated the spatiotemporal distribution of species diversity and community structure of ciliates in the intertidal sandy sediments of Huokun'ao beach, Nanji Islands National Marine Natural Reserve based on sample collections in November 2013 (autumn), February (winter), May (spring) and August (summer) 2014. The results showed highly diverse and abundant ciliates in the intertidal sediments of the beach, where a total of 148 species representing 19 orders and over 70 genera were identified. The abundance and species composition of benthic ciliates showed significant correlation with seasons and sediment depths. Bacterivorous ciliates constituted the most abundant group, followed by carnivores and algivores. The predominance of bacterivores indicated that the ciliate community in the intertidal sediment of Huokun'ao was not a typical interstitial ciliates fauna, but a pattern similar to those in muddy sand sediments with high level of organic matter. This is likely a subsequent effect oflong-term human activities. In spite of the impact, the high diversity of ciliates indicates that the benthic environment in the Huokun'ao beach and its surrounding area is in fair condition, which is attributed to the biodiversity conservation measures adopted, e.g. the relocation of surrounding residents and facilities.
PROKARYOTIC ENDOCYTOBIONTS OF PELOMYXIDAE
Chistyakova L.V.1, Berdieva M.A.2, Kostygov A.Yu.34, Frolov A.O.3
1 - Centre of Core Facility of SPSU "Culturing
