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MITOCHONDRIAL GENOMES OF AMOEBOZOA
стр.179-191
Bondarenko N., Smirnov A., Nassonova E., Glotova A., Fiore-Donno A.M.
In this mini-review, we summarize the current knowledge on mitochondrial genomes of Amoebozoa. Amoebozoa is a major, early-diverging lineage of eukaryotes, containing at least 2,400 species. At present, 32 mitochondrial genomes belonging to 18 amoebozoan species are publicly available. A dearth of information is particularly obvious for two major amoebozoan clades, Variosea and Tubulinea, with just one mitochondrial genome sequenced for each. The main focus of this review is to summarize features such as mitochondrial gene content, mitochondrial genome size variation, and presence or absence of RNA editing, showing if they are unique or shared among amoebozoan lineages. In addition, we underline the potential of mitochondrial genomes for multigene phylogenetic reconstruction in Amoebozoa, where the relationships among lineages are not fully resolved yet. With the increasing application of next-generation sequencing techniques and reliable protocols, we advocate mitochondrial genomes as a promising tool for understanding evolutionary patterns in Amoebozoa.
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MOLECULAR PHYLOGENY OF APHELIDIUM ARDUENNENSE SP. NOV. - NEW REPRESENTATIVE OF APHELIDA (OPISTHOSPORIDIA)
стр.192-198
Tcvetkova V.S., Zorina N.A., Mamkaeva M.A., Karpov S.A.
Aphelids (Aphelida) are poorly known parasitoids of algae that have raised considerable interest because of their phylogenetic position as phagotrophic protists sister to Fungi. Together with Rozellida and Microsporidia they have been classified in the Opisthosporidia but seem to be more closely related to the Fungi rather than to the Cryptomycota and Microsporidia, the other members of the Opisthosporidia. Molecular environmental studies have revealed high genetic diversity within the aphelids, but only four genera have been described: Aphelidium, Amoeboaphelidium, Paraphelidium and Pseudaphelidium. Here, we describe the life cycle of a new species of Aphelidium, Aph. arduennense. Molecular phylogenetic analysis of its 18S rRNA indicates that Aph. arduennense is sister to Aph. tribonematis, and together with Aph. melosirae they form a monophyletic cluster. Within the aphelids, this cluster is distantly related to Paraphelidium and Amoeboaphelidium.
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EFFECT OF HEAT SHOCK ON THE CELL CYCLE DURATION OF ALGAE-CONTAINING AND ALGAE-FREE CILIATES CLIMACOSTOMUM VIRENS
стр.199-205
Karajan B.P., Leonova O.G., Bobyleva N.N., Popenko V.I.
Cells of algae-containing (“green”) and alga-free (“white”) strains of the ciliate Climacostomum virens were compared for their responses towards a 1 h pulse of temperature stress. Although the upper heat shock temperature limits for the two strains were different (40-41 °C for “green”, and 37-38 °C for “white” cells), the responses to high temperature were similar. The delay in the completion of cell cycle depended on the cell cycle stage at which heat shock was given. Cells exposed to heat shocks at G1 stage or at the late dividing stage and returned back to 22 °C did not show any noticeable cell cycle lengthening. The most prominent effect was observed when the cells were heat-shock treated at the early dividing stage. In this case, heat shock resulted in up to 4 h delay of the cell cycle completion. It was found that in all experiments, when heat shock was given at different stages of division, the cell cycle duration of the progeny cells was significantly longer (42-50 h) than that of the control cells (21-25 h).
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CRITHIDIA DOBROVOLSKII SP. N. (KINETOPLASTIDA: TRYPANOSOMATIDAE) FROM PARASITOID FLY LYPHA DUBIA (DIPTERA: TACHINIDAE): MORPHOLOGY AND PHYLOGENETIC POSITION
стр.206-214
Ganyukova A.I., Malysheva M.N., Smirnov P.A., Frolov A.O.
The article provides characteristics of a new parasite, Crithidia dobrovolskii sp.n., which was isolated from the tachinid fly captured in the Leningrad Region of Russia. The presented description of Crithidia dobrovolskii sp.n. is based upon light microscopic, ultrastructural, and molecular phylogenetic data. Molecular phylogenetic analyses of SSU rRNA gene and GAPDH gene sequences have demonstrated that the new species is most closely related to Crithidia fasciculata.
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DIATOM ASSEMBLAGES OF THE BRACKISH BOLSHAYA SAMORODA RIVER (RUSSIA) STUDIED VIA LIGHT MICROSCOPY AND DNA METABARCODING
стр.215-235
Selivanova E.A., Ignatenko M.E., Yatsenko-Stepanova T.N., Plotnikov A.O.
Diatoms are highly diverse and widely spread aquatic photosynthetic protists. Studies of regional patterns of diatom diversity are substantial for understanding taxonomy and biogeography of diatoms, as well as for ecological perspectives and applied purposes. DNA barcoding is a modern approach, which can resolve many problems of diatoms identification and can provide valuable information about their diversity in different ecosystems. However, only few studies focused on diatom assemblages of brackish rivers and none of them applied the genetic tools. Herein, we analyzed taxonomic composition and abundance of diatom assemblages in the brackish mixohaline Bolshaya Samoroda River flowing into the Elton Lake (Volgograd region, Russia) using light microscopy and high-throughput sequencing of the V4 region of the 18S rDNA gene amplicons. In total, light microscopy of the samples taken in 2011-2014 and 2018 allowed to distinguish 39 diatom genera, represented by 76 species and infraspecies taxa. Twenty three species of diatoms were recorded in the river for the first time. Next-generation sequencing revealed a larger number of diatom taxa (26 genera and 47 OTUs in two samples vs. 20 genera and 37 species estimated by light microscopy). As a result, sequences of Haslea, Fistulifera, Gedaniella were recorded in the river for the first time. Significant differences in the data obtained with molecular and light microscopy approaches are discussed. Some V4 18S rDNA sequences were characterized by a low similarity with homologues from the reference database. We revealed high spatial-temporal heterogeneity of the diatom assemblages, occurrence of freshwater species together with brackish and marine ones, and predominance of benthic and plankto-benthic species. Thus, investigations of diatoms in brackish rivers based on both morphological and molecular approaches provide a good chance of improving an understanding of diversity, ecology and biogeography of Bacillariophyta.
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REAL-TIME OBSERVATIONS ON THE DEVELOPMENT OF INTRANUCLEAR PARASITE NUCLEOPHAGA AMOEBAE (ROZELLOMYCOTA) IN THE CULTURE OF THECAMOEBA QUADRILINEATA
стр.236-245
Gordetskaya O., Mesentsev Ye., Kamyshatskaya O., Michel R., Walochnik Ju., Smirnov A., Nassonova E.
Nucleophaga amoebae belongs to the phylum Rozellomycota (Opisthokonta), a widespread clade of parasites, considered as intermediate link between fungi and microsporidia. This organism is an obligate intranuclear parasite of the free-living amoeba Thecamoeba quadrilineata. The life cycle of this organism is difficult to study, many details require further clarification, and available light-microscopic images are limited in number and quality. We performed real-time observations on the process of parasite propagation in amoeba culture using Eppendorf Cell Imaging Plates and Differential Interference Contrast (DIC) microscopy. Development of the parasite was traced from the engulfment of spores by the amoeba cell to the production of a new generation of spores. Nucleophaga cells proliferate inside the host nucleus. The earliest intranuclear developmental stages that we observed were rounded uninucleate cells located at the margin of the host nucleolus. Growth resulted in formation of a large multinucleate plasmodium, which further became segregated into numerous individual uninucleate sporoblasts. After a period of maturation, sporoblasts transformed into the rounded spores enclosed in the sporophorous vesicle, probably formed by the remnants of the membrane of the plasmodium. At the final stage of the developmental cycle the amoeba cell died, its envelope, as well as the nuclear membrane broke, and the spores were released into the environment. The developmental cycle took approximately 5 days. Infected amoebae never divided, so we can suggest that the infection suppressed mitosis in the host cell.
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PROTISTOLOGIST WLADIMIR TIMOPHEYEVICH SCHEWIAKOFF (1859-1930). ON THE SHORES OF THE GULF OF NAPLES
стр.246-255
This article narrates the history of Acantharia research in the Gulf of Naples (Mediterranean Sea) by the well-known Russian scientist, Professor W.T. Schewiakoff, as well as his efforts to study Foraminifera and Ciliophora in the same water basin. All those activities are presented against a background of the protistologist's own life story.
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