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Protistology ■ 39
LAND USE AND LITTER CHEMISTRY IMPACT MICROBIAL DECOMPOSER COMMUNITIES AND LITTER DECOMPOSITION IN TROPICAL LOWLANDS OF SUMATRA, INDONESIA
Krashevska V.1, Malysheva E.2, Klarner B.1, Mazei Y.32, Maraun M.1, Widyastuti R.4, Scheu S.1
1 - J.F. Blumenbach Institute of Zoology and Anthropology, Georg August University Göttingen, Berliner Straße 28, 37073 Göttingen, Germany
2 - Penza State University, Russia
3 - Lomonosov Moscow State University, Russia
4 - Institut Pertanian Bogor - IPB, Department ofSoil Sciences and Land Resources, Damarga Campus, Bogor 16680, Indonesia
We investigated how the conversion of rainforest into jungle rubber, intensive rubber and oil palm plantations affects the decomposer community and decomposition processes. Further, we investigated the role of litter chemistry in structuring the decomposer system. In total 192 litterbags were placed into the field: 3 litter types (forest, rubber, oil palm) in 4 land use systems, with 2 harvest times and 8 replicates, each. After 6 and 12 months litterbags were collected and litter mass loss was measured, testate amoebae and microbial communities were studied, and litter element concentrations were measured. The decomposition in converted systems was slower as compared to rainforest; and litter of oil palms and rubber decomposed faster than that of forest. A total of 58 species oftestate amoebae (TA) colonized the litter. Species number and density of TA, as well as microbial biomass (MB) were high in rainforest and jungle rubber and decreased significantly in rubber and oil palm plantations. Further, TA density and MB was highest in rubber litter, whereas TA species number was at a similar levels in rubber and forest litter. Overall, our data indicate negative effects of rainforest conversion on the structure and functioning of decomposer community and, thereby litter decomposition. Further, testate amoebae and microorganisms were interactively affected by litter element concentrations. The data suggest that element ratios of litter material as basal resource of the decomposer food web exhibit strong bottom-up control on the structure of decomposer communities and decomposition processes
RHIZOPOD ANALYSIS IN THE PEAT-LAKE SEDIMENTS OF THE MOUNTAIN MIRE "BEZRYBNOE" IN THE SOUTH OF MIDDLE SIBERIA
Kurina I.V., Blyakharchuk T.A.
Institute of Monitoring of Climatic and Ecological Systems of SB RAS, Tomsk [email protected]
The research is devoted to rhizopod analysis (analysis of the testate amoebae complexes) in peat-lake sediments. The aim is the reconstruction of hydrological conditions in the mire during its development in the late Holocene. The study site Bezrybnoe Mire lies in Yergaki Natural Park in the Western Sayan Mts, southern Middle Siberia (52°51' N, 93°21' E, 1300 m a.s.l.). The thickness of sediments is 6 m, ofwhich the lower 2 m — gyttja, the upper 4 m - peat composed mainly of remnants of sphagnum moss. Age ofpeat at a depth of 4 m is 2,420 cal yr BP. Total 80 testate amoeba taxa was revealed. The dominant species were: Amphitrema wrightianum, Centropyxis aculeata, C. gibba, Difflugia globulus, Euglypha rotunda, Schoenbornia smithi, Trinema lineare, T. enchelys. There are both oligotrophic and minerotrophic species. 22 species were met only in gyttja. Water table depth (WTD) reconstruction is made on the basis of species optima obtained in our study of modern oligotrophic and minerotrophic mire habitats in the south of Western Siberia using the transfer function (training set includes 115 samples). Decrease of WTD in the mire are observed 2350-2300, 1850-1800, 1650, 1450, 1350 1100-900, 400-0 cal yr BP and increase - in 2400, 2000, 1900, 1800-1700, 1600-1500, 1400, 1300, 800-500 cal yr BP. Minerotrophic testate amoebae species were prevailed in the studied sediments. However, there were also oligotrophic species. For the reconstruction of WTD during development of such mires the information is needed about optima of both oligotrophic and minerotrophic species. The work was supported by RFBR grant (16-3460057).
BENTHIC CILIATES ON HERON ISLAND REEF, AUSTRALIA Langlois G.A.
Bryant University, Smithfield, RI USA [email protected]
Field studies conducted at the Heron Island Research Station, located in the Capricorn region of the Great Barrier Reef, revealed complex protistan communities. Heron Reef, home to about two-thirds of the coral species found on the GBR, has experienced repeated bleaching episodes in the past decade. This study, with comparisons to similar observations in 2006, emphasizes the diversity of ciliates and diatoms found in reef sediments. Observations included the interactive role of the protistan component of a coral reef, in particular the dynamics of opportunistic and/or potentially
40 • "PROTIST—2016
pathogenic forms associated with damaged corals undergoing disease conditions, such as Brown Band disease. These altered communities are characterized by rapid tissue breakdown in hard corals, coupled with high levels of dissolved organic matter. Samples were taken by direct capture, observed with phase contrast and epifluorescence microscopy, recorded by video and photomicrography, and fixed for later identification and genomic studies. The relative abundance of diatoms/flagellates/ ciliates appears to show a higher proportion of photosynthetic species as compared to previous observations. Brown Band ciliates were not found on the corals, in the sediments, on algal surfaces, or in the plankton prior to bleaching in late January, posing the question oftheir location when not acting as opportunistic pathogens.
"CANDIDATUS MEGAIRA": AN EMERGING GENUS OF BACTERIAL ENDOSYMBIONTS WIDESPREAD IN CILIATES AND OTHER PROTISTS
Lanzoni O.1, Shaidullina A.2, Sabaneyeva E.2, Castelli M.1,3, Lebedeva N.4, Potekhin A.2, Petroni G.1
1 - Department of Biology, University of Pisa, Pisa, Italy
2 - Faculty ofBiology, St. Petersburg State University, Saint Petersburg, Russia
3 - Department of Veterinary Medicine, University of Milan, Milan, Italy
4 - Centre of Core Facilities "Culture Collections of Microorganisms", St Petersburg State University, Saint Petersburg, Russia [email protected]
" Candidatus Megaira" (Rickettsiaceae) is a recently described genus of obligate intracellular bacteria, which are phylogenetically closely related to the pathogen Rickettsia. Sequences representatives of genus " Candidatus Megaira" can be split in at least 3-4 species level sub-clades. These sequences have been found in association to evolutionary far related host lineages (e.g. unicellular and multicellular algae, corals and hydras). The type species of the genus, "Candidatus Megaira polyxenophila", has been found in several ciliates as well as in other protists. In ciliates, " Candidatus Megaira polyxenophila" can infect different cell compartments (macronucleus and cytoplasm) according to the host species. Herein, we provide the characterization of a second "Candidatus Megaira" species inhabiting the cytoplasm ofthe green ciliate Paramecium bursaria. Within the same host cell, this novel " Candidatus Megaira" presents polymorphic features such as the association with endosymbiotic algae, or the possible
presence offlagellum at some stage ofthe life-cycle. Moreover, we performed several trans-infection experiments using different species of newly characterized " Candidatus Megaira" in order to understand how representatives of this genus can be spread in the aquatic environment and how they influence the host fitness within the same ciliate population. We also investigated the interaction between " Candidatus Megaira" and other symbiotic bacteria already inhabiting or invading the same host cell. All together, our findings highlight the necessity of a better understanding of the life-cycles of this widespread, but poorly investigated, endosymbiont.
THE GENOMIC STUDY OF AGAR PRODUCING RED ALGA GRACILARIOPSIS CHORDA Lee J.M.1, Yang E.C.2, Graf L.1, Yoon H.S.1
1 - Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Korea
2 - Marine Ecosystem Research Division, Korea Institute of Ocean Science & Technology, Ansan, 15627, Korea
Red algae (Rhodophyta) played an important role in the evolution of photosynthetic organisms as plastid donor(s) in chlorophyll-c containing algae including cryptophytes, haptophytes, stramenopiles, and alveolates. Most red algal species are important components in marine ecosystems, serving as a shelter for diverse marine organisms and contributing as primary producers. Many red algal species are heavily cultivating as food and industrial purposes such as agar and carrageenan production. Despite of these importances, only several red algal genomes have been reported among more than 7,000 species. From the major multicellular red algal group of theFlorideophyceae, only one genome was fully sequenced to date. To fill the gap of our understanding on red algae, here we analyzed a new genome of the multicellular red algal species Gracilariopsis chorda, which is one of major cultivar as food and agar production in Korea. Using the long-read single molecule sequencing (PacBio) platform, we completed whole-genome of 89.6 Mbp (49% GC content, 1,098 contigs) that encodes a total of 9,992 predicted proteins. We discuss the interesting story of genome reduction/expansion and gene duplication in red algal genomes at this meeting.
AN ANCESTRAL BACTERIAL DIVISION SYSTEM IS WIDESPREAD IN EUKARYOTIC MITOCHONDRIA
Leger M.M.1, Petru M.2, Zarsky V.2, Eme L.1, Vlcek C.3, Harding T.1, Lang B.F.4, Elias M.5, Dolezal P.2,
