MAIN GOALS AND TASKS

The head of Laboratory
Professor S.O. Movsesyan

The Laboratory of experimental parasitology has been created as a department of the Institute of Parasitology, RAS, on the initiative of corresponding member of RAS M.D. Sonin and Academician of NAN RA S.O. Movsesyan (by Scientific Council of Institute of Parasitology, RAS, Protocol # 2 from 23.02.1994, coordinated with Section of Biological Sciences, RAS). The Laboratory was supported by Presidium of RAS, which transferred additional resources for this to the Institute. S.O. Movsesyan has been elected Head of the Laboratory and continues this work till now.

According to Act of Presidium of RAS from 14.02.2006, the Laboratory of Experimental Parasitology has been included into structure of the Center of Parasitology of A.N. Severtsov's Institute of Ecology and Evolution, RAS.

Main Area of Scientific Studies

(Program of fundamental scientific studies of state academies of sciences at 2013-2020):

• 52. Biological diversity
  Fundamental and specific parasitology

Main goals of studies:

• study of parasite-host relationships;
• neurobiological aspects of parasite-host systems;
• genetic structure of populations of various helminth species;
• formation of helminthofaunistic complexes at modern transforming environment conditions;
• prognostics of helminthological situation;
• zoogeography and phylogeny of helminths.

Main results of scientific studies from last 10 years:

- species and biological variety of lung helminths of animals and humans in Russia, Armenia, Bulgaria, Poland has been defined. A presence of 31 nematode species (including 28 from fam. Protostrongylidae, 3 from fam. Dictyocaulidae) and 1 Taeniidae cestode species (Echinococcus granulosus) parasitizing in 18 species of wild and domesticated animals from fam. Cervidae,Bovidae, Canidae, Hyaenidae, Leporidae and also in humans has been diagnosed;

- taxonomic classification of Protostrongylidae family nematodes and biological classifications of 32 lung helminth species found have been developed.

Protostrongylidae, Leiper, 1926

A biological classification of these species is based on analysis of their life cycles dividing them into three types:

- 1st type is characterized by direct development from egg to imago without intermediate hosts. This type includes nematodes from fam. Dictyocaulidae – geohelminths.

- 2nd type uses two hosts: vertebrate definitive one and invertebrate intermediate one, in this case being land snails. These are biohelminths from fam. Protostrongylidae.

- 3rd type also uses two hosts, but in this case both definitive and intermediate hosts are vertebrates.

This type is characteristic of the tapeworm Echinococcus granulosus (Taeniidae). In its case definitive hosts are mainly carnivorous mammals, while main intermediate ones are ruminants and humans.

(Movsesyan S.O., with scientific collectives of Institute of Zoology NAN RA, Bulgarian and Poland Academies of Sciences.)

Life cycle, habitats and cercaria morphology of bird schistosomes.

Studies of genome of the bird schistosome Trichobilharzia szidati have recently produced 37 unique DNA sequences from 274 (n=7) to 391 bp (n=30) (entered into GenBank with numbers KP889985-890021).

A reliable similarity of these sequences with 5' end of reverse transcriptase (RT) domain of penelope-like retro transposones (PLE) from Schistosoma japonicum (Sj2) and S. mansoni (Perere-10) with identity of 42 and 35% respectively has been found. Phylogeny of these sequences and its connection with T. szidati evolution has also been found. Penelope-like elements are retroelements currently studied but poorly. Their structural peculiarity is a presence of RT-domain together with endonuclease domain (GIY-YIG) and specific long terminal repeats. Current studies are involve structure and polymorphism of complete PLE in bird schistosome genomes.

Character of genetic polymorphism in loci of mitochondrial and nuclear genome in trematodes (Fasciolidae, Schistosomatidae) from various populations from Russia, Armenia, Belarus, etc.

Studies of life cycles, distribution and population structure of bird schistocomes continue. Character of genetic polymorphism in several intermediate hosts of these trematodes – mollusks Lymnaea stagnalis, L. palustris – also continue to be studied.

(Gulyaev A.S., Voronin M.V., with Institute of Gene Biology RAS.)

As a result of study of life cycles of causative agents of a dangerous zoonotic helminthosis – trichinellosis caused by Trichinella spiralis, T. pseudospiralis, T. nativa nematodes – immunological marks of plasmocytic reaction in infected laboratory animals (mice, rats, rabbits) depending on the agent species and dosage of infection has been defined. It was established that Trichinella antigens are species specific and so antigen obtained from one Trichinella species can't be fully successful in diagnosing another one.

Role of various vertebrate and invertebrate species in Trichinella circulation has been studied.

(Movsesyan S.O., Odoevskaya I.M., with Institute of Zoology NAN RA and Srkrjabin's Institute of Fundamental and Applied Parasitology.)

Serotonin-immunoreactive components in helminths’ nervous system.

- New foreground data on presence, localization and functional significance of several neuromediators (serotonin, neuropeptide FMRF-amide, and also a new atypical regulatory substance with neurotransmitter properties – nitrogen oxide) in trematodes at various stages of their life cycle has been obtained. A comparative analysis has shown that these neuromediators play an important functional part in trematodes at all stages of their development.

- A fundamental summation and analysis of data on functional morphology of nervous system of parasitic flatworms – trematodes and cestodes – has been performed. In the new monograph a comparative analysis of functional organization of nervous systems of helminths from several taxonomic groups at various stages of their life cycles including hermaphroditic and parthenogenetic generations in trematodes and larval and adult stages in cestodes has been given. Basing on new experimental material, questions of functional significance of neuromediators studied in regulation of activity of the parasitic worms' muscles were studied.

- Role of serotoninergic components in formation of locomotory activities of cercariae of trematodes Cryptocotyle lingua and Himasthla elongata has been experimentally established.

(Terenina N.B., Tolstenkov O.O., Malyutina T.A., with Section of Biology, University of Turku, Finland.)