CC BY
31
70 • "PROTIST—2016
Italy
2 - Department of Invertebrate Zoology, St. Petersburg State University, St. Petersburg, Russia
3 - Department of Zoology, Andhra University, Visakhapatnam, India
4 - Department of Biotechnology, Andhra University, Visakhapatnam, India [email protected]
Ciliates are known since a long time to be potential hosts for bacteria. Some of the most investigated species belong to the so-called Holospora-like bacteria (HLB) group, which includes all known Holospora species and " Candidatus Gortzia" genus. HLB are obligate endosymbionts, inhabiting the macronucleus or the micronucleus of certain species of Paramecium and, less frequently, Frontonia. They are Gram-negative, non-motile Alphapro-teobacteria with a distinctive life cycle involving two different morphotypes: the smaller and almost roundish reproductive (RF) form, and the much more elongated, rod-like infectious form (IF). In the present work we describe a novel species belonging to "Ca. Gortzia" genus, detected in P. multimicronucleatum, a ciliate in which HLB have never been reported before. This novel endo-symbiont shows unusual features respect its relatives, such as deep variations in IF morphology and capability to infect occasionally host cytoplasm. It presents small, roundish RF (2.5-3.3 ^m) and rod-shaped IF. Two morphotypes of IF were detected in different periods: a shorter IF at the beginning (6.9-10.7 ^m), and a longer one (8.2—14.7 ^m) with irregular distribution of periplasm after one year of cultivation. The latest were found together with a high number of transient forms (TF), which appeared long (6.7—15.5 ^m), rod-shaped and not yet differentiated in IF at ultrastructural level. All forms show a constant diameter of 0.7-0.8 ^m. No production of "connecting piece" during host cell division was observed. We propose for this novel HLB from India the name of " Candidatus Gortzia shahrazadis".
INTERACTION OF DIFFERENT SYMBIOTIC BACTERIA IN THE CILIATE PARAMECIUM Shaidullina A.1, Lanzoni O.2, Lebedeva N.3, Potekhin A.1
1 - Faculty of Biology, St Petersburg State University, Saint Petersburg, Russia
2 - Department of Biology, University of Pisa, Pisa, Italy
3 - Centre of Core Facilities "Culture Collections of Microorganisms", St Petersburg State University, Saint Petersburg, Russia [email protected]
Multiple bacterial symbioses are rather common phenomenon in ciliates. Some intracellular bacteria, like "Candidatus Megaira polyxenophila", apparently do not produce any effect on the host, and their mode of interaction with ciliate is unknown; some other, like Holospora, are highly infectious bacteria actively exploiting the host resources. However, little is known about interactions among endosymbiotic bacteria inhabiting the same host cell. The simultaneous infection of a ciliate with several bacteria has been observed but not studied in detail. Finally, the ability of a bacterium to enter and associate with the host cell already occupied by another symbiont remains unclear; indeed the possible competition for the same cell compartment between the "native" bacterium and an "invader" has never been investigated. We analyzed how the host cell reacts to multiple infections, and how different symbiotic bacteria interact inside the host. For this purpose, four strains of Paramecium caudatum harboring " Candidatus Megaira polyxenophila" in macronucleus were experimentally infected with representatives of several Holospora species. During our observations " Candidatus Megaira polyxenophila" prevented development of macronuclear Holospora species, thus showing the tendency to be the only occupier of the host macronucleus. On the contrary, "Candidatus Megaira polyxenophila" allowed the entrance of Holospora undulata in the host micronucleus, even in presence of other cytoplasmic endosymbionts. Results on reciprocal infections (paramecia harboring Holospora infected with " Candidatus Megaira polyxenophila") also suggested that symbionts protect their cell compartment from invasions by other bacteria in order to ensure their persistence and spreading in the environment. Supported by RFBR 16-04-01195.
CANINE BABESIOSIS IN MOSCOW REGION OF RUSSIA
Shaitanov V.M., Yastreb V.B.
K.I. Skriabin All-Russian Institute for Fundamental
and Applied Parasitology of Animals and Plants
The blood smears of dogs were examined in Moscow region under light microscope in 2011-2014. If Babesia merozoites were detected the samples were examined with IFA-tests SNAP 4Dx against for Ehrlichia canis, Anaplasma phagocytophilum, Borrelia burgdorferi s.l., Dirofilaria immitis. The microfilaria were visualized in samples after concentration. Differential staining of acid phosphatases was used to distinguish Dirofilaria microfilaria. Anamnesis of infected dogs was analyzed. The ticks were removed
