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AN OVERVIEW OF THE GENUS QUADRULELLA (ARCELLINIDA: HYALOSPHENIIDAE) FROM BULGARIA, WITH DESCRIPTION OF QUADRULELLA DEFLANDREI SP. NOV
стр.53-68
Bankov N., Todorov M., Ganeva A.
All species of the genus Quadrulella recorded in Bulgaria are described morphologically and morphometrically and distributional data for them are provided. A new testate amoeba Quadrulella deflandrei sp. nov. isolated from Sphagnum mosses is described. The newly described species resembles Q. symmetrica in its general shape, but differs from it by about twice the size and significantly more and larger shell plates (maximum size 15-19 µm in Q. deflandrei vs. 10-12 µm in Q. symmetrica). On the other hand, Q. deflandrei has a similar size as Q. quadrigera and Q. squtellata but can be easily distinguished from them by the size and arrangement of the plates: in Q. quadrigera shell plates are relatively small and similar in size (8-10 µm), arranged in numerous rows, often mixed with single round or elliptical plates; in Q. scutellata, small quadrangular plates are usually superimposed at the junctions of the larger plates. The analysis of the variation coefficients shows that the population of the newly described species is homogeneous and all characters and ratios measured are weakly to moderate variable (CV range from 4.98% to 9.78%). The shell length, breadth and depth, as well as length/breadth ratio are the most stable characters (CV between 4.98% and 6.79%). Moderate variability is observed for the aperture and breadth/aperture ratio (9.24% and 9.72%, respectively). Our study of many individuals of Q. longicollis gives us evidence to support the view that it is a well-defined and independent species, clearly distinguishable from Q. symmetrica and Q. variabilis. We discuss the high morphological and morphometric variability of Q. symmetrica and the need for molecular studies of European narrow-shelled and tubular forms, very similar to the recently described South African species Q. madibai, to elucidate their taxonomic status. We synonymise Quadrulella symmetrica var. irregularis Penard, in Wailes and Penard, 1911 with Quadrulella longicollis (Taranek, 1882).
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PHYLOGENETIC ANALYSIS OF THE PROTEIN HOMOLOGS OF HEMOXYGENASES HO-1 AND HO-2 INFERRED FROM THE TRANSCRIPTOMES OF DINOFLAGELLATES
стр.69-79
Pechkovskaya S.A., Filatova N.A.
The potentially toxic marine dinoflagellates Prorocentrum cordatum (Ostenfeld) Dodge, 1975 are responsible for harmful algal blooms in many coastal ecosystems and have recently colonized the brackish-water Baltic Sea. Their ability to adapt to changing environmental conditions is partly mediated by cytoprotective proteins that provide the effective physiological stress response. One such protein, heme oxygenase (HO/HSP32), not only catalyzes the degradation of heme but also protects cells from oxidative stress caused by a number of environmental factors. In this study, we phylogenetically characterized the HO-like protein sequences of dinoflagellates found in the unannotated transcriptomes represented in the Marine Microbial Eukaryote Transcriptome Sequencing Project database. The homologues sequences identified in the database shared amino acid identity with HO family proteins of other taxa and contained typical conserved motifs. Phylogenetic analysis showed that HO-like homologs are widely represented in the dinoflagellate transcriptomes. Overall, sequences of dinoflagellates can be classified into two distinct groups. The first group is closely related to other unicellular protists and cyanobacteria. The second group clusters separately from all other taxa. We made a comparative analysis of the HO-1-like and HO-2-like protein trees to evaluate topological and branch length differences between the trees. We found that both trees possessed different topologies, thus indicating that these two proteins evolved at different rates.
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BREFELDIN A DISTURBS GOLGI COMPLEX INTEGRITY BUT DOES NOT IMPAIR ECDYSIS IN THE DINOFLAGELLATES PROROCENTRUM CORDATUM
стр.80-87
Pozdnyakov I., Berdieva M., Kalinina V., Pechkovskaya S., Matantseva O.
The marine planktonic dinoflagellate Prorocentrum cordatum (syn. Prorocentrum minimum) is a thecate species capable of ecdysis, i.e. rearrangement of the cell covering in response to different stressors. During the process of ecdysis, P. cordatum cells shed the plasma membrane and outer amphiesmal vesicle membrane, and become immotile, covered only by thecal plates and the new plasma membrane. At this stage, the cells can be considered as thecal cysts. Then, they complete ecdysis by leaving the old thecal plates and restoring motility, i.e. excyst. To elucidate the role of vesicular transport in the cell covering rearrangement, we tested the effect of brefeldin A, the inhibitor of vesicular transport from the endoplasmic reticulum to the Golgi complex widely used in cell biology, on the cellular structure of P. cordatum and its ability to ecdyse. We found out that brefeldin A blocked vesicular trafficking from the endoplasmic reticulum to the Golgi complex, since we observed disassembly of the Golgi complex in cells treated by brefeldin A at 0.1 µg/ml for 1 h. Moreover, such a treatment did not increase mortality in P. cordatum culture at the time scale of 6 h. Nevertheless, our experiments demonstrated that brefeldin A affected neither shedding of outer membranes nor discarding of thecal plates during the stressor-induced ecdysis. Based on our findings, we conclude that vesicle trafficking from the endoplasmic reticulum to the Golgi complex and further to the plasma membrane is not essential to the process of membrane and theca shedding. However, this route still can be involved in the process of new amphiesma’ maturation, which is discussed in this work.
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EXPERIMENTAL INFECTION OF THE FLY CALLIPHORA VICINA WITH THE TRYPANOSOMATID ANGOMONAS DEANEI AND CROSS-INFECTION BETWEEN DIFFERENT CALLIPHORID SPECIES
стр.88-95
Ganyukova A.I., Malysheva M.N., Frolov A.O.
In this study, we present the results of an experimental infection of larvae and imagoes of the fly Calliphora vicina with the trypanosomatids Angomonas deanei from two laboratory cultures (A. deanei MN and A. deanei TCC036E). In accordance with our results, the rectum of an adult fly is the main site of the parasites localization where they form massive clusters, while no persistent infection develops in the intestines of the larvae. Horizontal transmission between imagoes of C. vicina was demonstrated in both cases of the infection: with A. deanei MN and A. deanei TCC036E. In a series of experiments on the transmission of A. deanei MN between three species of flies (Calliphora vicina, Lucilia sericata, and Protophormia terraenovae), we demonstrated successful infection between the flies of different species.
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