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Protistology ■ 83
1 - Unité d'Ecologie, Systématique et Evolution, Université Paris-Sud 11, France
2 - Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Catalunya
3 - Institució Catalana de Recerca i Estudis Avangats (ICREA)
Opisthokonts, one of the largest eukaryotic supergroups, is divided into two major clades: the Holozoa, encompassing animals and their unicellular relatives, and the Holomycota, including fungi and their unicellular relatives. The earliest-branching lineage in Holomycota, which has received many names (e.g. Nucleariidae, Cristidiscoidia, Discicristata), remains poorly studied. This group of phagotrophic filose amoebae bears contrasting features in comparison with those of their close relatives, the parasitic Opisthosporidia and the osmotrophic fungi. It originally contained a single genus, Nuclearia, which includes naked amoebae of ca. 40 ^m cell diameter that feed on filamentous cyanobacteria in freshwater environments. More recently, Fonticula alba was included as sister to Nuclearia spp. With much smaller cell size and bacterivore, this amoeba presents an aggregative multicellular fruiting body. Here we describe the new genus Parvularia nov. gen., a small filose amoeba formerly called Nuclearia sp. ATCC50694, and we compare its morphological features with those of the genera Nuclearia and Fonticula. We also review the whole nucleariid lineage at the onset ofHolomycota, focusing on their diversity, ecology and evolutionary importance. SSU rRNA-based phylogenetic analyses including environmental sequences suggest that nucleariids are relatively scarce and thrive exclusively in freshwater systems. Based on existing transcriptomic data for Parvularia and novel data for a canonical Nuclearia strain, we carried out phylogenomic analyses to study the internal phylogeny of the whole group. Nucleariids occupy a key evolutionary position, such that mapping phenotypic traits on the phylogeny of Opisthokonts will help understanding important evolutionary transitions such multicellularity, parasitism or osmotrophy.
TESTATE AMOEBA IN BAU SEN AND BAU TRANG LAKES, BINH THUAN PROVINCE, VIETNAM
Tran Q.H., Nguyen T.H.T. Vietnamese-Russian Tropical Center [email protected]
The species composition and distribution of testate amoebae in Bau Sen and Bau Trang lakes (Binh Thuan Province, Vietnam) were investigated. Fifty-three species, varieties and forms have been
identified from the water column and sediments. Twenty-seven species, varieties and forms from the genera Arcella, Centropyxis, Cyclopyxis, Difflugia and Pyxidicula were found in Vietnam for the first time. The updated list oftestate amoebae in Vietnam now includes 286 taxa. The genera Arcella, Centropyxis and Difflugia are characterized by the highest frequency of occurrence. The species diversity of Arcella, Centropyxis, Difflugia was the highest. Centropyxis aculeata, Arcella discoides, Difflugia schurmanni, Netzelia oviformis and Difflugia limnetica were the most common species. Some taxa have shown restricted distribution, e.g. Lesquereusia modesta was found in Bau Trang lake with a high frequency of occurrence, but was not observed in Bau Sen lake. The number of observed species,varieties and forms in each lake is 34. The average number ofthe species per sample on the shores of the lakes subjected to human agricultural activity was significantly higher than in the samples from the shores of the lakes with less anthropogenic disturbance. The curves of "cumulative species number vs. sampling effort" are well fitted by equations S = 7.60N0-69 for Bau Sen lake and S = 12.52N0-46 for Bau Trang. The curves are unsaturated, which indicates that more intensive investigations oftestate amoebae should be expected to reveal more species.
DIVERSITY OF THE GENUS MONOCERCO-MONOIDES
Treitli S.C.1, Kotyk M.2, Yubuki N.1, Vlasakova J.1, Sramova E.1, Smejkalova P.1, Novotna K.K.1, Cepicka I.2, Hampl V.1
1 - Charles University in Prague, Faculty of Science, Department of Parasitology, Prague, Czech Republic
2 - Charles University in Prague, Faculty of Science, Department of Zoology, Prague, Czech Republic [email protected]
Monocercomonoides sp. is a genus of small flagellates belonging to the order Oxymonadida. They live as intestinal endosymbionts of insects, but some of them can be found also in the intestine ofvertebrates. In this work we sequenced the SSU rRNA of 35 different strains of Monocercomonoides isolated from various insect and vertebrate hosts and from unused cesspit. We have performed phylogenetic analysis in order to understand the diversity of this genus. Our preliminary results indicate large variation among strains at the genetic level with some strains having a typical 1800 bp SSU and some having around 3000 bp SSU sequence. The strains formed two clades, potentially distinct genera, however the position of these clades in the oxymonad trees is unclear and we have so far not found any good diagnostic feature discriminating
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between them. Morphological analysis of selected strains from the major clade, which we consider as the genus Monocercomonoides, failed to find suitable characters for species delineation and it is also very difficult to assign lineages to described species. Based on the morphology and host origin, we assume that the lineage containing Chinchilla isolate PA203, and isolates from guinea pig and Chameleo cristatus represent species M. exilis.
CILIOFAUNA OF NATURAL AND ARTIFICIAL ECOSYSTEMS OF KHABAROVSK TERRITORY
Tribun M.M., Zhykov A.V., Nikitina L.I. Far Eastern State Transport University [email protected]
Environmental degradation due to pollution by industrial, agricultural and municipal waste gave rise to serious problems, associated with the violation of the ecological balance in ecosystems and the biosphere. Ciliata - an important object in the model laboratory experiments, as they are used as an indicator of the degree of human impact on the environment. Sampling was carried out in small rivers of the Khabarovsk territory (rivers Krasnaya, Chernaya, Berezovaya) and aeration tanks in Khabarovsk (town Berezovii). During inventory ciliofauna has been identified 152 species of ciliates. The greatest number of species represented Oligohymenophorea class - 33 and Vorticellidae family - 12 species. 3 species of ciliates were eurybiontic (Paramecium caudatum, Colpidium campylym, Uronema marinum). Species ciliofauna similarity between small rivers and aeration tanks is 30% (according to Sorensen coefficient). Ciliata specific types of small rivers Khabarovsk - 14 (32% of the number of species recorded in small rivers), in aeration tanks - 32 (57%). Specific types belonged Armophorea classes - 3 kinds, Litostomatea - 3 kinds, Phyllopharyngea - 8 species, Oligohymenophorea - 13 species. Thus, faunal analysis of ciliofauna aquatic ecosystems Khabarovsk shows how the presence of similar species found in a variety of biological communities and the presence of specific representatives. In particular, this phenomenon is characteristic of biocenosis aeration.
OVERVIEW OF THE WHOLE SPECTRUM OF MITOCHONDRIAL DIVERSITY WITHIN THE CILIATE CLADE
Tsaousis A.D.12, Williams L.T.12, Gentekaki E.3, Lynn D.4, van der Geizen M.5, Wass M.N.2
1 - Laboratory of Molecular and Evolutionary Parasitology
2 - School of Biosciences, University of Kent
3 - School ofScience, Mae Fah Luang University
4 - University ofBritish Columbia
5 - School of Biosciences, University of Exeter [email protected]
Mitochondria are important organelles in all eukaryotes and their protein composition and function(s) depend on the lifestyle of the organism harboring them. While being very well studied, their functional distribution amongst ciliates remains a dark box. The Ciliophora group is currently one of the most studied lineages of single-cell eukaryotes, mainly due to their abundance in diverse habitats. Despite this, investigations on the cell biology and the functional diversification of their organelles have been limited, with the exception of certain species, mainly Paramecium, Tetrahymena and Nyctotherus. These organisms have been shown to harbor either typical mitochondria or hydrogen-producing mitochondria, while their mitochondrial genome has an unusual codon usage. In this project, we used the recently acquired transcriptomic and genomic data to predict the functional diversity of mitochondria and related organelles within the group of ciliates. Our analyses demonstrate that members of the ciliates harbor distinctive classes of mitochondria, with a variety of functions and adaptations. Two species have been predicted to have remnant mitochondria (mitosomes) and one of them hydrogen-producing mitochondria (hydrogenosomes). Surprisingly, we are currently observing the whole spectrum of functional classification of mitochondria just within ciliates; Ciliophora is an exceptional model group to monitor in real time the functional adaptations of mitochondria.
TESTATE AMOEBA TRANSFER FUNCTION PERFORMANCE ALONG LOCALISED HYDROLOGICAL GRADIENTS Tsyganov A.N.1, Mityaeva O.A.1, Mazei Yu.A.12, Payne R.J.13
1 - Department of Zoology and Ecology, Penza State University, Krasnaya str. 40, Penza, 440026, Russia
2 - Department ofHydrobiology, Lomonosov Moscow State University, Leninskiyegory, 1, Moscow, 119991, Russia
3 - Environment Department, University of York, Heslington, York YO10 5DD, United Kingdom [email protected]
Testate amoeba transfer functions are widely used for reconstruction ofpalaeo-hydrological regime in peatlands. However, the limitations ofthis approach have become apparent with increasing attention to validation and assessing sources of uncertainty. This paper investigates effects of peatland type and
