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92 • "PROTIST—2016
closely related species and are proper markers for ciliates barcoding.
THE INTRICATE EVOLUTIONARY HISTORY
OF RhoBTB PROTEINS
Zihala D.1, Klimes V.1, Rivero F.2, Elias M.1
1 - University ofOstrava, Faculty ofScience, Department of Biology and Ecology, Chittussiho 10, 710 00 Ostrava, Czech Republic
2 - Centre forCardiovascular and Metabolic Research, The Hull York Medical School and Department of Biological Sciences, University of Hull, Cottingham Road, Hull HU6 7RX, UK [email protected]
The Rho family is one of the major subgroups of the huge superfamily of Ras-like GTPases. Rho proteins are known primarily as regulators ofvarious pathways that are connected to the actin cytoskele-ton (cell movement, polarization, morphogenesis etc.). These proteins usually contain only the Rho-type GTPase domain, but some of them possess also a tandem of two so-called BTB domains and are called RhoBTB proteins. The BTB domain is a protein-protein interaction domain and is often a part of proteins that are connected to protein ubiquitination through Cullin3-dependend E3 ligases. Proteins with the domain architecture characteristic for RhoBTB proteins have been reported only from metazoans and dictiosteliid slime moulds, but this distribution was deduced from a phylognetically very limited survey. We have utilized the currently available wealth of genomic and transcritpomic data from diverse eukaryotes, including a wide coverage of protist taxa, and found out that RhoBTB proteins occur in many additional eukaryotic lineages. Although scattered, the phyletic pattern of RhoBTB genes is compatible with a hypothesis that a primordial RhoBTB gene was present already in the last eukaryotic common ancestor. Interestingly, RhoBTB proteins from some taxa (Amoebozoa, Apusomonadida, and Cryptomonadida) proved to possess a RING/U-box domain inserted into the first BTB domain. RING and U-box are related domains that constitute a class of E3 enzymes, so our findings further support the idea that RhoBTB3 proteins ancestrally served as components of ubiquitin-mediated regulation. These and other findings of our evolutionary analyses of RhoBTB proteins will be presented and discussed.
THE STATE OF ART IN THE TAXONOMY OF
"HELIOZOA"
Zlatogursky V.V.
Department of Invertebrate Zoology, Faculty of
Biology, Saint-Petersburg State University [email protected]
"Heliozoa" is a former taxon of spherical axopodial protists. These organisms, being outwardly similar have revealed to be not necessarily related. Some of lineages are now placed into the proper "supergroups", while many deviant forms still remain "orphans". The most diverse group — the centrohelids — recently was placed in Haptista along with haptophytes and their internal taxonomy also was considerably revised showing interesting examples of parallel evolution. But in comparison to other groups with a developed taxonomy "Heliozoa" still seem to be undeservingly neglected. Many taxa of flagellates, ciliates and in a less degree of amoebae get much more attention, while heliozoan taxonomy suffer from the lack of skilled taxonomists. The great amount of their diversity is likely to be unknown. The heliozoans require closer attention, being ubiquitous in freshwater, marine (both planktonic and benthic) and soil environments, important consumers of bacteria, protists and even micrometazoans. But the taxonomic impediment currently prevents them from being incorporated into ecological and biogeographic studies. Many heliozoans, especially centrohelids, are easy to maintain in the culture, have a rich morphology and potentially can serve a good model for addressing many of fundamental questions of protistology, including a species problem, the endemism vs ubiquity dilemma and the evolution of cell coverings. Many of them can be indicators ofwater quality and should be included to biodiversity indexes. But first of all, their taxonomy need to be evaluated and the main proportion of species should be described on the modern level. Study support: RFBR grants 15-04-18101_a, 15-29-02749-ofi_m.
THE RELIABILITY OF PROTOZOANS AS INDICATORS OF AQUATIC ECOSYSTEM HEALTH Zolotarev V.A.
I.D. Papanin Institute for biology of inland waters Russian Academy of Sciences (IBIW RAS) [email protected]
Metapopulations of microbial organisms occur worldwide wherever their required habitats are realised. This is a consequence of ubiquitous dispersal driven by huge population sizes, and the consequently low probability of local extinction (Finlay, 2002). Microorganisms should be used in biomonitoring for several compelling reasons. (1) A cosmopolitan distribution facilitates comparisons of test results in geographically different regions. (2) Problems of scale are diminished. (3) Replicability
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is as good as, or better than, tests with larger organisms. (4) Environmental realism is higher than in tests using larger organisms. (5) The number of test species is dramatically increased when using microorganisms, thus displaying natural variability much better than tests with a limited array of larger organisms, etc. (Cairns, 2005). Biodiversity of the whole aquatic ecosystem depends on the biodiversity of the microbial communities (Algae, Protozoa, Bacteria) at the basis of the trophic pyramid. The term 'indicator species' is usual in literature on bioindication of water quality, but we more tend to accept the term 'indicator communities', or 'model communities', that could be robust both for biological monitoring and ecotoxicology. Diversity and relative abundance of ciliates and other protozoans can be used as indicators of toxic pollution and acidification. Multivariate statistics were used to design "the scale of toxicity" across a gradient of toxicant stress and organic compounds. A new index of periphyton flagellates (IPF) as indicator of the trophic status of a water-body was developed (Zolotarev, 2007). For the foreseeable future, protozoans could be robust for ecosensors and ecorobots.
NONOOGAMOUS SEXUAL REPRODUCTION IN THE POLAR CENTRIC DIATOM ARDISSONEA CRYSTALLINA Davidovich N.A., Davidovich O.I., Podunay Y. A. Federal State Budget Scientific Institution «T.I. Vya-zemsky Karadag Scientific Station — Nature Reserve
of the Russian Academy of Sciences», Kurortnoe, Feodosia, Crimean Republic, 298188 Russia e-mail: [email protected] At first glance, according to some morphological and habit features Ardissonea crystallina (C. Agardh) Grunow should be regarded as belonging in pennate diatoms. However, molecular phylogeny analysis strongly suggests this species to be placed among centric diatoms. It is well known that centric diatoms reveal oogamous mode of sexual reproduction. Exceptions are cases of autogamy. We studied clonal cultures of A. crystallina and were able to initiate sexual reproduction in the mixtures of clones. Heterothallic sexual reproduction was shown to be nonoogamous. Gametes produced by male and female gametangia were more or less equal by size. Gamete behaviour and morphology were different. Male gametes had no flagella; at the same time, they were able to produce thin cytoplasmic projections similar to those of some araphid pennates (Tabularia fasciculata, T. tabulata, Ulnaria ulna, etc.). Female gametes were located in the maternal frustules and did not leave them until fertilization. Each male gamete moved in part amoeboidly to the place of singamy and penetrated in the gap between slightly opened valves of the maternal frustule. The described finding raises a question about possibility ofindependent evolution ofisogamy in polar centric diatoms. This study was supported by the Russian Foundation for Basic Research (grant No 15-0400237 A).
