CC BY
21
66 • "PROTIST—2016
LYING ON THE SURFACE: NEW DATA ON THE EPISYMBIONTS OF CILIATES Sabaneyeva E.1, Lanzoni O.2, Lebedeva N.3, Benken K.4, Potekhin A.5, Petroni G.2
1 - Department of Cytology and Histology, Saint-Petersburg State University, Saint-Petersburg, Russia
2 - Department of Zoology, University of Pisa, Pisa, Italy
3 - Core Facility Center for Cultivation of Microorganisms, Saint-Petersburg State University, Saint-Petersburg, Russia
4 - Core Facility Center for Microscopy and Microanalysis, Saint-Petersburg State University, Saint-Petersburg, Russia
5 - Department ofMicrobiology, Saint-Petersburg State University, Saint-Petersburg, Russia [email protected]
Protists often form symbiotic associations with prokaryotes. Ciliates are especially well known for harbouring endosymbiotic and ectosymbiotic bacteria, the relationship between the partners ranging from mutualism to parasitism. Epibionts can be found both in anaerobic and in free living aerobic ciliates, however, so far they have never been reported in paramecia. Here we present morphological (DIC, AFM, CLSM, TEM) and molecular characterization of the bacterium fouling cells of Paramecium primaurelia strain isolated from nature in Cyprus. At the last stage of infection, epibionts formed a thick coat on the cortex of the ciliate causing complete loss of cilia, changes of the cell shape, dwarfing, and finally, the host death. Fluctuations of the ciliate population density of the infected strain registered throughout long term observations of the laboratory culture imply parasitoid nature of the epibiont. In preliminary FISH experiments, epibionts were easily revealed with the universal eubacterial probe Eub 338, however, they never showed positive signal when hybridized with probes specific for Alpha-, Beta-, Gamma- or Deltaproteobacteria. Molecular characterization was done following the full-cycle rRNA approach and association of the epibionts with the host was confirmed by FISH experiments with newly designed species-specific probes. The obtained 16S rDNA sequence showed a similarity of circa 82% with Alphaproteobacteria class, thus suggesting that epibionts are extremely unusual novel organisms. Phylogenetic analysis, which is under way, will enlighten the evolutionary position of this enigmatic organism, presumably, either a basal alphaproteobacterium or a fast-evolving line within the order Rickettsiales.
BIODIVERSITY OF BENTHIC DINOFLA-GELLATES ALONG THE SOUTHERN COAST OF OMAN WITH EMPHASIS ON POTENTIALLY TOXIC SPECIES Saburova M.
Kuwait Institute for Scientific Research, P.O. BOX 1638, Salmiya 22017, Kuwait; long-term consultancy [email protected]
Benthic dinoflagellates have attracted considerable research attention during the last decades due to their morphological and taxonomic diversity, ecological significance in marine benthic ecosystems, and their capability to produce toxins and cause toxic blooms in the coastal areas. A pilot taxonomic survey of the benthic dinoflagellates was performed for the first time at the Arabian Sea coast along Dhofar Governorate of the Sultanate of Oman in the vicinity of Salalah City at five sampling sites on February 2014 and 2016. It has been shown that the bottom sediments and the surface of brown and red macroalgae along the southern Omani coast were inhabited by taxonomically diverse and abundant assemblages of sand-dwelling and epiphytic dinoflagellates. A total of 38 dinoflagellate species belonging to five orders were recorded in this study including Dinophysiales, Gymnodiniales, Gonyaulacales, Peridiniales, and Prorocentrales. High diversity of the sand-dwelling dinoflagellates was supported mainly by gymnodinioid and peri-dinioid taxa. In contrast, members of Coolia, Gambierdiscus, Ostreopsis, and Prorocentrum were among the most abundant and diverse epiphytic dinoflagellates. A number of known toxin producers were observed including the ichthyotoxic dinoflagellates of the genus Amphidinium, the okadaic acid producing Prorocentrum species, the cooliatoxin producing Coolia, the palytoxin producer Ostreopsis, and the ciguatera-related Gambierdiscus species. The presence of known toxic dinoflagellate species may indicate a potential risk of toxicity in the marine environment of the southern Omani coast, and underscores the need for further studies on taxonomy, ecology and toxicology of benthic dinoflagellates in Oman.
DEVELOPMENT OF A MULTIPLE-DRUG SELECTION SYSTEM FOR DUAL-TRANSFORMATION OF THE OYSTER PARASITE PERKINSUS MARINUS
Sakamoto Hirokazu1, Hirakawa Yoshihisa1, Ishida Ken-ichiro1, Kita Kiyoshi23, Matsuzaki Motomichi2
1 - Faculty of Life and Environmental Sciences, University of Tsukuba
2 - Department of Biomedical Chemistry, Graduate
