European journal of protistology最新文献

The ciliate Paramecium bursaria possesses cell organelles called trichocysts that have defensive functions. Paramecium bursaria is capable of symbiosis with Chlorella variabilis, and the symbiotic algae are situated in close proximity to the trichocysts. To clarify the relationship between trichocysts in P. bursaria and the presence or absence of the intracellular symbiotic C. variabilis, this study compared the regeneration capacity of trichocysts in alga-free and algae-bearing P. bursaria. In addition, trichocyst protein abundance was measured when alga-free P. bursaria specimens were artificially infected with Chlorella. After completely removing trichocysts from P. bursaria cells by treatment with lysozyme and observing them after 24 h, the percentage of regenerating trichocysts in the entire cell was significantly higher in alga-free cells than that in algae-bearing cells. We also developed a simple method for the isolation of high-purity trichocysts to quantify trichocyst protein amounts. There was a significant difference in the trichocyst protein abundance of P. bursaria before and one week after mixing with Chlorella (i.e., after the establishment of symbiosis with algae). This study shows the importance of trichocysts in alga-free P. bursaria as well as their competition with symbiotic C. variabilis for attachment sites during the algal infection process.

Protists can endure challenging environments sustaining key ecosystem processes of the microbial food webs even under aridic or hypersaline conditions. We studied the diversity of protists at different latitudes of the Atacama Desert by massive sequencing of the hypervariable region V9 of the 18S rRNA gene from soils and microbial mats collected in the Andes. The main protist groups in soils detected in active stage through cDNA were cercozoans, ciliates, and kinetoplastids, while the diversity of protists was higher including diatoms and amoebae in the microbial mat detected solely through DNA. Co-occurrence networks from soils indicated similar assemblages dominated by amplicon sequence variants (ASVs) identified as Rhogostoma, Euplotes, and Neobodo. Microbial mat networks, on the other hand, were structured by ASVs classified as raphid-pennate diatoms and amoebae from the genera Hartmannella and Vannella, mostly negatively correlated to flagellates and microalgae. Additionally, our phylogenetic inferences of ASVs classified as Euplotes, Neobodo, and Rhogostoma were supported by sequence data of strains isolated during this study. Our results represent the first snapshot of the diversity patterns of culturable and unculturable protists and putative keystone taxa detected at remote habitats from the Atacama Desert.

The morphology and molecular phylogeny of a new ciliate, Conchophthirus sinanodontae n. sp., which was discovered in the freshwater mussel Sinanodonta woodiana (Lea, 1834) from the Chilsancheon River, Buyeo-gun, South Korea, were investigated. The new species was characterized and could be distinguished from congeners by a combination of characters including the ovate body outline, four to six oral polykinetids deeply embedded in the upper wall of the buccal cavity, six to ten vestibular kineties, 34–49 ventral and 36–53 dorsal somatic kineties. The genetic differences among C. sinanodontae n. sp. and other congeners with available 18S rDNA sequences further support its distinctness. Moreover, the phylogenetic analyses based on the 18S rDNA sequences show that the new species clusters with other congeners, corroborating the monophyly of the genus Conchophthirus. The Conchophthirus clade nests within the cluster of Dexiotricha spp., Loxocephalus luridus, and Haptophrya spp.

Cyphoderia compressa has only been described from supralittoral environments, as a psammobiont, with salinities from 1.33 to 36.00 ‰. Other Cyphoderia species such as those in the C. ampulla species complex are more ecologically and environmentally widespread, occurring as free-living individuals within water bodies or in association with vegetation, and over a wider salinity range, including freshwater. We postulate that C. compressa may not be as restricted in terms of its environmental or ecological distribution. To this end, we examined a variety of water and sediment samples from Scottish localities, ranging from supralittoral to inland freshwater environments. The Scottish material occurs as a psammobiont within supralittoral beach sands and is newly recorded within sands from freshwater to brackish stream sections and along the margin of the freshwater Loch Lomond. It is also recorded from freshwater to brackish settings as part of the stream and pond water biota, associated biofilm and vegetative material. Test morphology is more variable than previously appreciated, including those with a papillate fundus, and many that are not as laterally compressed as typified by the species. Differences in plate morphology and size were also noted, as well as a novel arcuate cross-cutting ridged cement structure, that is restricted to C. compressa.

The phylogeny of brown algae (Phaeophyceae) has undergone extensive changes in the recent past due to regular new scientific insights. We used nuclear 18S rDNA with an extensive dataset, aiming to increase the accuracy and robustness of the reconstructed phylogenetic trees using a simultaneous sequence-structure approach. Individual secondary structures were generated for all 18S rDNA sequences. The sequence-structure information was encoded and used for an automated simultaneous sequence-structure alignment. Neighbor-joining and profile neighbor-joining trees were calculated based on 186 phaeophycean sequence-structure pairs. Additionally, sequence-structure neighbor-joining, maximum parsimony and maximum likelihood trees were reconstructed on a representative subset. Using a similar approach, ITS2 rDNA sequence-structure information was used to reconstruct a neighbor-joining tree including 604 sequence-structure pairs of the Laminariales. Our study results are in significant agreement with previous single marker 18S and ITS2 rDNA analyses. Moreover, the 18S results are in wide agreement with recent multi-marker analyses. The bootstrap support was significantly higher for our sequence-structure analysis in comparison to sequence-only analyses in this study and the available literature. This study supports the simultaneous inclusion of sequence-structure data at least for 18S to obtain more accurate and robust phylogenetic trees compared to sequence-only analyses.

After Gulielmina was erected and Ophiotheca was resurrected based on some species originally included in Perichaena (Trichiaceae, Trichiales, Myxomyxetes), some specimens from the Herbarium of Fungi of Nanjing Normal University previously identified as Perichaena species were reexamined from morphological and two-gene (nuclear 18S rDNA and elongation factor-1 alpha) phylogenetic perspectives. In this study, two new myxomycete species, Gulielmina subreticulospora and Ophiotheca dictyospora, are described. Gulielmina subreticulospora shows the following character combination: branched plasmodiocarps, single peridium with circular protrusions in the inner surface, capillitium (2.4–)2.8–3.0(–3.4) μm in diameter, spores (7.4–)8.0–8.5(–9.0) μm in diameter and sub-reticulated. Ophiotheca dictyospora shows the following character combination: sessile sporocarps to short plasmodiocarps, single peridium with a densely irregular network and protrusions in the inner surface, capillitium (2.7–)3.5–5.0(–7.1) μm in diameter, uneven, decorated with spines of uneven size, spores (7.7–)8.2–8.6(–9.4) μm in diameter including obviously complete cristate reticulation with serrated edges, with deep and clear grids. Both new taxa were compared with related species and their genetic isolation was statistically tested. Moreover, a comprehensive morphological description and a detailed figure plate are provided for Perichaena verrucifera, and its phylogenetic position is determined.

Coleps is a common genus of pelagic ciliates in freshwater and brackish water habitats. Classification and phylogeny of Coleps species are, however, still full of confusion. In this study, we investigated Coleps shanghaiensis n. sp., collected from a river in Shanghai, China, by living observation, protargol staining, and molecular methods. Coleps shanghaiensis is about 70–90 µm × 35–55 µm in size, has a barrel-shaped body with three posterior spines, and possesses 21–24 ciliary rows, each composed of two perioral dikinetids and 19–22 monokinetids, and six caudal cilia. In SSU rRNA gene phylogenies, C. shanghaiensis fell within the clade of subspecies of Levicoleps biwae, which questions the validity of the genus Levicoleps. Furthermore, the biogeography of the genus Coleps is discussed.

Despite their high abundance and wide distribution in ecosystems, most protists remain unknown to the public. Although science communication approaches were developed in historical times to raise public awareness of these ‘enigmatic’ taxa, many aspects have not been considered in the spotlight of modern techniques. We present selected ideas and activities on how to attract the public to unicellular eukaryotes. We give examples of how protists can be included in educational work. We explain that trained non-experts can understand and teach others how to recognize protists, where they live, in which habitats they can be found, what they look like and why they are important. Consequently, members of the public can learn how environmental threats impact not only the lives of protists but also ours, e.g., by the accumulation of microplastics through an aquatic food web, up to fish used for human consumption. We suggest age-appropriate methods for application in workshops on protist recognition.

The subclass Trichostomatia (Ciliophora, Litostomatea) constitutes a well-supported monophyletic group, which includes ciliates exclusively found as symbionts of vertebrates, primarily herbivorous mammals. Recent molecular analyses reinforce the subclass monophyly, though almost all orders, suborders, families, and genera are found to be non-monophyletic. Here, we reconstructed the evolutionary history of the subclass Trichostomatia using a phylogenomic approach and discussed some systematic inconsistencies. We propose a new Ophryoscolecidae genus, Dagostonium, to include Diplodinium polygonale. Monoposthium cynodontum is transferred to the genus Cycloposthium.

Rustic aquaculture systems represent a sustainable production alternative in the world, providing appropriate conditions for the establishment of epibiotic ciliates on crayfish. However, the impact of epibiotic ciliates on the aquaculture production has been insufficiently studied hitherto. The objective of this work was to identify the epibiotic ciliates on the surface of the crayfish Procambarus (Austrocambarus) sp. and analyze whether there is any correlation between seasonality and environmental conditions in an artificial pond in Chiapas, Mexico. The crayfish were collected during dry and rainy seasons to investigate their ciliate epibionts. Some physical and chemical parameters of the sampled water were measured and correlation matrix analyses were applied to detect possible relationships between the presence of ciliates and environmental parameters. Thirteen species belonging to the subclasses Peritrichia and Suctoria were identified. Significant differences were found for some environmental parameters and species recorded in both seasons. The present data could help to better understand the relationship bewteen the epibiotic ciliate community on crayfish and some environmental parameters in aquaculture systems.