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Volume 56, Issue 2

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Publication date: 24.11.2017

Licence: CC BY-NC-ND licence icon

Editorial team

Editor-in-Chief Orcid Krzysztof Wiąckowski

Issue content

Fernando Gómez, Kostas Kiriakoulakis, Enrique Lara

Acta Protozoologica, Volume 56, Issue 2, 2017, pp. 71 - 76

https://doi.org/10.4467/16890027AP.17.006.7481
We examined the planktonic dinoflagellate Achradina pulchra by light and scanning electron microscopies from the South and North Atlantic oceans. The basket-like skeleton has been interpreted as a thick cell covering or pellicle of organic composition, or as a siliceous endoskeleton. The skeleton of Achradina is known only from fresh material, being absent in preserved samples, sediments or the fossil record. X-ray microanalysis revealed that the endoskeleton of Achradina is composed of celestite (strontium sulfate) with traces of barite (barium sulfate), two minerals that readily dissolve after cell death. To date, Acantharia and polycystine radiolarians (Retaria) were the only known organisms with a skeleton of this composition. We can now add a dinoflagellate to the list of such mineralized skeletons, which influence on the biogeochemical fluxes of strontium and barium in the oceans. Moreover, we provided the first molecular data for a skeleton-bearing dinoflagellate. Molecular phylogeny based on the SSU rRNA gene sequences revealed that Achradina and several environmental clones branched as an independent lineage within the short-branching dinokaryotic dinoflagellates. To date, seven clades of dinokaryotic dinoflagellates are known living as symbionts in the endoplasm of Acantharia and polycystine radiolarians. Because celestite built skeletons were unknown outside radiolarians, we suggested that the ancestors of Achradina acquired the genes implicated in the deposition of strontium and barium from radiolarian hosts though a horizontal gene transfer event between microbial eukaryotes.
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Simona Benčaťová, Eva Tirjaková

Acta Protozoologica, Volume 56, Issue 2, 2017, pp. 77 - 91

https://doi.org/10.4467/16890027AP.17.007.7482
This is the first detailed study on the morphology of the resting cysts of an oxytrichid ciliate, Rigidohymena quadrinucleata. Resting cysts were investigated using light microscopy, SEM and TEM. The cyst wall is composed of four distinct layers (from inside to outside), namely the metacyst, the endocyst, the mesocyst and the ectocyst with spine-like protuberances. The cysts of R. quadrinucleata belong to the kinetosome-resorbing (KR) type, which is typical for oxytrichids. The processes of encystation and excystation were observed only in the light microscopy. During the encystation process, the trophic cell changes in shape and volume due to dehydration, four macronuclear nodules fuse into a compact mass, the ciliature is resorbed and cyst wall is formed. The most significant feature is surface ornamentation and yellowish color of resting cysts. We also focuse for the first time on excystation process of R. quadrinucleata. We identified two excystation modes: (i) standard and (ii) rare mode. The beginning of both excystation is characterised by the formation of excystation vacuole which helps the excysting cell to break the cyst wall. The specimen regenerates within a thin, flexible membrane. During the standard mode, the cell leaves the resting cyst in the membrane that is resorbed in the environment. During the rare mode, the excystation vacuole and the pressure of the regenerating cell break the transparent membrane that remains in the resting cyst. The results suggest that not only ciliate resting cysts, but also the excystation process is much more variable than what literature data indicate. 
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Renu Gupta, Jeeva Susan Abraham, Sripoorna Somasundaram, Ravi Toteja, Seema Makhija, Hamed A. El-Serehy

Acta Protozoologica, Volume 56, Issue 2, 2017, pp. 93 - 107

https://doi.org/10.4467/16890027AP.17.008.7483
Morphology, morphogenesis and molecular phylogeny of a freshwater oxytrichid ciliate, Aponotohymena isoaustralis n. sp. collected from Sanjay Lake (28°36′51″N, 77°18′14″E), Delhi, India, were studied. The described species is characterized by a flexible body, with body size (in vivo) of about 148 × 46 µm and yellowish green cortical granules. Morphological characters exhibit: undulating membranes in Notohymena–pattern; two macronuclei and absence of micronucleus (amicronucleate); about 36 adoral membranelles; 18 frontoventral-transverse (FVT) cirri; one right and one left marginal row separated posteriorly; 6 dorsal rows; 7 caudal cirri arranged in 2 + 2 + 3 pattern (constant). In the present study, a detailed description of all the developmental stages is also provided. Prominent distinguishing features of the new species are the absence of micronucleus, 7 caudal cirri (constant), yellowish green cortical granules aligned along the margins and irregularly distributed throughout the cell. They may also be randomly concentrated as clusters along the left margin and posterior end of the cell. Molecular phylogeny based on small subunit rDNA sequence data suggests sister relationship of Aponotohymena isoaustralis n. sp. with Notohymena apoaustralis and Aponotohymena australis (Notohymena australis) which cluster in a clade with Paraurostyla weissei and Paraurostyla coronata. Further analysis of nucleotide sequence of SSU rDNA also suggests that A. isoaustralis n. sp. is distinct from the type species A. australis.
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Alexander V. Kurilov

Acta Protozoologica, Volume 56, Issue 2, 2017, pp. 109 - 118

https://doi.org/10.4467/16890027AP.17.009.7484
An improved impregnation method for ciliates has been described with a new formulation for silver proteinate synthesized in situ, that avoids necessary its long-time laboratory synthesis or use of expensive commercial protargol. Compared to conventional techniques, the proposed protocol is more time-saving, reduces the consumption of chemicals and excludes some hazardous ones (e.g. xylene). Structures that are impregnated such as nuclear apparatus, infraciliature, cortical and cytoplasmic microtubules are stained almost identical compared to other protargol methods. Advantages of this method allow us to merge it successfully with ecological quantitative studies of various natural communities of ciliates and provide correct identification of species during such investigations.
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Maria A. Sousa, Barbara N. Santos, Cristina Carvalhal, Mario Steindel

Acta Protozoologica, Volume 56, Issue 2, 2017, pp. 119 - 127

https://doi.org/10.4467/16890027AP.17.010.7485
Two KP1(–) strains of Trypanosoma rangeli (SC-58, SC-61) isolated from the wild rodent Phyllomys dasythrix from Santa Catarina (Brazil) were compared with some KP1(+) reference stocks from different Latin America countries, and also with Trypanosoma lewisi. The strains were analyzed by some morphological and biological features, and by biochemical and molecular techniques. The mean total length (TL) of the bloodstream trypomastigotes of T. rangeli varied between 31.3–33.0 µm, and those of T. lewisi (adult forms) was 28.2 µm, values within the variation known for each species. In T. rangeli KP1(+) and T. lewisi, the nucleus was located in the anterior portion of the body, with nuclear indexes (NI) ≥ 1.2, as typically described for both species. Differently, most trypomastigotes of the KP1(–) stocks presented NI ≤ 1.0. Another striking feature of the KP1(–) strains was their very fastidiously growth in axenic cultures when compared with the KP1(+) stocks and T. lewisi. Three isoenzyme loci (MDH, IDH and PGM) clearly distinguished T. rangeli and T. lewisi, and the distinction between the KP1(+) and KP1(–) strains was possible at MDH, PGM and GPI loci. All T. rangeli strains presented the typical 760 bp amplicon derived from their KP2 minicircles. However, the KP3 products of the KP1(+) strains were a single large band (~330bp), whereas those of the KP1(–) had two distinct bands (350 and 300 bp). T. lewisi presented 700 and 400 bp amplicons, as previously reported. The peculiarities of T. rangeli isolates from P. dasythrix corroborate a possible speciation process within this taxon.
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Hubert Okła, Krzysztof Piotr Jasik, Beata Rozwadowska, Jan Słodki, Danuta Urbańska-Jasik, Michał Grelowski, Ewa Chmielik, Aleksandra Słodki, Marta Albertyńska, Aniela Grajoszek

Acta Protozoologica, Volume 56, Issue 2, 2017, pp. 129 - 137

https://doi.org/10.4467/16890027AP.17.011.7486
The course of babesiosis in humans is characterized by various intensity levels − from a subclinical level to the severe one − associated with multiple organ failure, which leads to death. The aim of this study was to evaluate the effect of 21-day and 6-month invasion of B. microti on Wistar rats spleen. Histological changes in the rats’ spleen were characterized by swelling of splenic tissue, especially the tissue adjacent to the capsule. In the structure of the white pulp in some rats, high concentrations of lymphocytes occurred. The boundary between the white pulp and red pulp was blurred. In the red pulp structure of rats, a lot of macrophages and extracellular deposits of bilirubin were present. The submicroscopic studies showed that the nuclear matrix was slightly shrunken. In the red pulp fragments of the damaged cells were located in the intercellular spaces. Near these areas, many thrombocytes were visible. The ultrastructural observation also revealed thickened endoplasmic reticulum membranes, local cellular swelling filled with amorphous substance, and digested erythrocytes. B. microti invasion affects the splenic morphology and ultrastructure in rats. The immunological hyperactivity and signs of inflammation indicate an important role of spleen in a fight against parasites. 
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