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In the hypotrich ciliate Euplotes, many individual basal bodies are grouped together in tightly packed clusters, forming ventral polykinetids. These groups of basal bodies (which produce compound ciliary organelles such as cirri and oral membranelles) are cross‐linked into ordered arrays by scaffold structures known as "basal‐body cages." The major protein comprising Euplotes cages has been previously identified and termed "cagein." Screening a E. aediculatus cDNA expression library with anti‐cagein antisera identified a DNA insert containing most of a putative cagein gene; standard PCR techniques were used to complete the sequence. Probes designed from this gene identified a macronuclear "nanochromosome" of ca. 1.5 kb in Southern blots against whole‐cell DNA. The protein derived from this sequence (463 residues) is predicted to be hydrophilic and highly charged; however, the native cage structures are highly resistant to salt/detergent extraction. This insolubility could be explained by the coiled‐coil regions predicted to extend over much of the length of the derived cagein polypeptide. One frameshift sequence is found within the gene, as well as a short intron. BLAST searches find many ciliates with evident homologues to cagein within their derived genomic sequences. [ABSTRACT FROM AUTHOR]

We describe a new genus and species of blood‐dwelling apostome ciliate, Lynniagrapsolytica n. gen., n. sp. (Apostomatida: Colliniidae). A distinct kinety "hook" pattern on the tomite's posterior ventral face, coupled with its marine habitat and use of a decapod host, readily distinguishes this ciliate from all known colliniids. We detected the parasite in ~12% of Pachygrapsuscrassipes (Brachyura: Grapsidae) crabs in a California estuary and confirmed its presence at a Baja California rocky intertidal site. As existing methods failed to adequately stain this ciliate, we developed a new miniaturized silver carbonate impregnation staining method that produced excellent somatic and nuclear stains in all five observed cell types. A possibly unique trait is the active invagination of the tropho‐tomont's anterior to form a temporary "pseudocytopharynx," likely used for feeding. Histological examination revealed that the ciliate invaded and damaged skeletal muscle, the heart, connective tissues, and gonads. Survivorship analysis indicated that infected crabs experienced 2.6 times greater daily mortality than uninfected crabs. Laboratory and field experimental infection attempts failed, suggesting a complex life cycle with outside‐host development. Phylogenetic analysis at the 18S and COI loci confirmed the ciliate's placement in the Colliniidae. We emend the diagnosis of Family Colliniidae. [ABSTRACT FROM AUTHOR]

A novel genus and species within the order Glissmonadida (Cercozoa, Rhizaria), Saccharomycomorphapsychra n. g., n. sp., is described from lichen in the Ny‐Ålesund region (High Arctic) and moss in the Fildes peninsula of King George Island (Maritime Antarctica). Cells were spherical and did not appear to present flagella in organic‐rich Potato Dextrose Agar medium where they were able to feed osmotrophically. Molecular phylogenetic analyses based on 18S rRNA gene sequence demonstrated that Saccharomycomorphapsychra belong to "clade T" within the order Glissmonadida (Cercozoa, Rhizaria). All three investigated strains could grow at 4 °C and had an optimum growth temperature of 12 °C, 20 °C, and 20 °C, while a maximum growth temperature of 20 °C, 20 °C, and 25 °C, respectively. In conclusion, we established the phenotypic identity of "clade T," which until now was exclusively detected by environmental sequences, and erect a new family Saccharomycomorphidae for "clade T." Nomenclatural, morphological and ecological aspects of this novel species are discussed. [ABSTRACT FROM AUTHOR]

Eimeria tenella is an obligate intracellular parasite in the phylum Apicomplexa. As described for other members of Apicomplexa, apical membrane antigen 1 (AMA1) has been shown to be critical for sporozoite invasion of host cells by E. tenella. Recently, an E. tenella paralogue of AMA1 (EtAMA1), dubbed sporoAMA1 (EtAMA3), was identified in proteomic and transcriptomic analyses of E. tenella, but not further characterized. Here, we show that EtAMA3 is a type I integral membrane protein that has 24% −38% identity with other EtAMAs. EtAMA3 has the same pattern of Cys residues in domains I and II of AMA1 orthologs from apicomplexan parasites, but high variance in domain III, with all six invariant Cys residues absent. EtAMA3 expression was developmentally regulated at the mRNA and protein levels. EtAMA3 protein was detected in sporulated oocysts and sporozoites, but not in the unsporulated oocysts or second‐generation merozoites. EtAMA3 is secreted by micronemes and is primarily localized to the apical end of sporozoites during host‐cell invasion. Additionally, pretreatment of sporozoites with rEtAMA3‐specific antibodies substantially impeded their invasion into host cells. These results suggest EtAMA3 is a sporozoite‐specific protein that is involved in host‐cell sporozoite invasion. [ABSTRACT FROM AUTHOR]

Three peritrichous ciliates, Zoothamnium arcuatum n. sp., Z. grossi n. sp., and Z. parahentscheli Sun et al., 2009, were collected from an estuary of the Taehwagang River, Korea. All these species were investigated based on live observations and silver staining, and their small subunit ( SSU) rRNA gene was also sequenced. Zoothamnium arcuatum can be identified by a goblet-shaped colony, double-layered peristomial lip, and abstomally shortened row 3 of infundibular polykinety 3 (P3). Zoothamnium grossi is morphologically characterized by an alternately branched stalk with the lowest secondary stalk diverging from the main part of colony, asymmetrically bell-shaped zooids, and three short, parallel ciliary rows in P3. Phylogenetic analysis revealed that the three Zoothamnium species described in this paper clustered with other members of the family Zoothamniidae, as expected. [ABSTRACT FROM AUTHOR]

The survival of an isolate of Hyphochytrium catenoides collected from soil in the Blue Mountains in eastern New South Wales, Australia, was tested under extreme conditions in the laboratory. This isolate recovered growth after being subjected to drying on filter paper, to heat while desiccated, to hypersalinity, to strict anaerobic conditions, to freezing temperatures, and to a short period in solutions at pH 2.8–11.2. The capacity to survive under these conditions in the laboratory suggests adaptation to fluctuating conditions in the soil. The partial DNA sequence of the 28S ribosomal RNA gene in the isolate from New South Wales was 98% similar to that in an isolate from Arizona with a similar morphology. [ABSTRACT FROM AUTHOR]

The involvement of ligninolytic and cellulolytic enzymes, such as laccase, lignin peroxidase, manganese peroxidase, carboxymethylcellulase (CMCase), and filter paper activity (FPA), in the decomposition process of leaf litter driven by 6 soil-inhabiting fungi imperfecti was studied under solid-state fermentations. All the tested fungi exhibited varied production profiles of lignocellulolytic enzymes and each caused different losses in total organic matter (TOM) during decomposition. Based on the results, the 6 fungi could be divided into 2 functional groups: Group 1 includes Alternaria sp., Penicillium sp., Acremonium sp., and Trichoderma sp., and Group 2 includes Pestalotiopsis sp. and Aspergillus fumigatus. Group 1, with higher CMCase and FPA activities, showed a higher decomposition rate than the fungi of Group 2 over the first 16 d, and thereafter the cellulolytic activities and decomposition rate slowed down. Group 2 showed the maximum and significantly higher CMCase and FPA activities than those of the Group 1 fungi during the later days. This, combined with the much higher laccase activity, produced a synergistic reaction that led to a much faster average mass loss rate. These results suggest that the fungi of Group 1 are efficient decomposers of cellulose and that the fungi of Group 2 are efficient decomposers of lignocellulose. During cultivation, Pestalotiopsis sp. produced an appreciable amount of laccase activity (0.56±0.09 U/ml) without the addition of inducers and caused a loss in TOM of 38.2%±3.0%, suggesting that it has high potential to be a new efficient laccase-producing fungus. [ABSTRACT FROM AUTHOR]

The morphology, morphogenesis and molecular phylogeny of Parabistichelladieckmanni (Foissner, 1998) Foissner, 2016, isolated from north China, were investigated. The Chinese population was characterized as having five to seven frontal cirri in corona, four to seven buccal cirri arranged in a row, two to four short frontal rows and two long frontoventral rows, three to seven transverse cirri, four macronuclear nodules, three dorsal kineties following a Gonostomum‐pattern, and caudal cirri absent. Morphogenetic research reveals that the main characteristics during binary fission are as follows: (1) the long left frontoventral row is formed by two or three anlagen; (2) the posterior part of the parental adoral zone of membranelles is renewed, and the oral primordium of the opisthe is formed intrakinetally; (3) FVT‐anlagen I to VI (or V, VII) produce each a frontal cirrus to form the frontal corona; (4) development of dorsal kineties follows the Gonostomum‐pattern. Phylogenetic analyses showed that P. dieckmanni does not group with other Parabistichella species. Therefore, the genus Parabistichella is polyphyletic. Additionally, Parabistichellavariabilis n. comb. (basionym: Bistichellavariabilis He & Xu, 2011) and Parabistichellacheni n. nom. (basionym: Parabistichellavariabilis Jiang et al., 2013) were suggested. [ABSTRACT FROM AUTHOR]

Microsporidia are a group of obligate intracellular parasites causing significant disease in human beings and economically important animals. Though a few spore wall proteins (SWPs) have now been identified in these intriguing species, the information on SWPs remains too little to elucidate the spore wall formation mechanisms of microsporidia. It has been well described that numerous proteins with tandem repeats tend to be localized on the cell wall of fungi and parasites. Previously, by scanning the proteins with tandem repeats in microsporidian Nosema bombycis, we obtained 83 candidate SWPs based on whether those proteins possess a signal peptide and/or transmembrane domain. Here, we further characterized a candidate protein (EOB13250) with three tandem repeats in the N‐terminal region and a transmembrane domain in C‐terminus of N. bombycis. Sequence analysis showed that the tandem repeat domain of EOB13250 was species‐specific for this parasite. RT‐PCR indicated that the expression of the gene encoding this protein started on the fourth day postinfection. After cloned and expressed in Escherichia coli, a polyclone antibody against the recombinant EOB13250 protein was prepared. Western blotting demonstrated this protein exist in N. bombycis. Immunofluorescence analysis (IFA) and immunoelectron microscopy analysis (IEM) further provided evidence that EOB13250 was an endospore wall protein. These results together suggested that EOB13250 was a novel spore wall protein of N. bombycis. This study provides a further enrichment of the number of identified spore wall proteins in microsporidia and advances our understanding of the spore wall formation mechanism in these obligate unicellular parasites. [ABSTRACT FROM AUTHOR]

We describe an inexpensive magnetic cell patterning method as a tool for protozoologists. The ciliate Vorticella convallaria is useful for various biofluidics applications. Here, we show that V. convallaria will ingest metal beads and that permanent magnets can be used to pattern cells in Petri dishes or a microfluidic device. Patterning is reversibly achieved by placing magnets at the point of desired cell attachment. Analogous magnetic manipulation could be performed using other phagocytic cells. [ABSTRACT FROM AUTHOR]

Symbioses between sponges and photosynthetic organisms are very diverse regarding the taxonomy and biogeography of both hosts and symbionts; to date, most research has focused on the exploration of bacterial diversity. The present study aims to characterize the culturable diversity of photosynthetic eukaryotes associated with sponges in the Aegean Sea, on which no information exists. Five microalgae strains were isolated from marine sponges; the strains were characterized by morphological features, and the 18S rRNA, 18S‐28S Internal Transcribed Spacer, and ribulose‐bisphosphate carboxylase large chain (rbcL) sequences. Our polyphasic approach showed that the strains belonged to the green‐alga Acrochaete leptochaete, the diatom Nanofrustulum cf. shiloi, the rhodophyte Acrochaetium spongicola, and the chlorachniophyte Lotharella oceanica. A. leptochaete is reported for the first time in sponges, even though green algae are known to be associated with sponges. Nanofrustulum shiloi was found in association with the sponges Agelas oroides and Chondrilla nucula, whereas information existed only for its association with the species Aplysina aerophoba. Acrochaetium spongicola was found for the first time in association with sponges in the eastern Mediterranean. Moreover, we report herein for the first time a sponge–chlorarachniophycean association. Our research revealed new diversity of microalgae associated with sponges and added new records of sponge species, previously unknown for their association with microalgae. [ABSTRACT FROM AUTHOR]

Blastocystis is a common intestinal protozoan in humans and various animals worldwide. A few studies have reported the genetic characterization of Blastocystis in pigs in China, but no epidemiological data are available from the Xinjiang Uygur Autonomous Region. In this study, 801 fecal samples were collected from seven scale pig farms in Xinjiang and tested by polymerase chain reaction and sequence analysis of the partial SSU rRNA gene. The average infection rate of Blastocystis was 21.7% (174/801), with 7.1% in preweaning piglets, 10.0% in postweaning piglets, 31.8% in fattening pigs, and 41.9% in sows (χ2 = 104.89; P < 0.01). Blastocystis subtypes ST1 (7/174), ST3 (2/174), and ST5 (165/174) were identified, with subtype ST5 being predominant in each of the pig farms and in each of the age groups. ST3 and ST5 were identified in preweaning piglets, and ST1, ST3, and ST5 were identified in postweaning piglets. In contrast, only the subtype ST5 was observed in fattening pigs and sows. Genetic polymorphisms were observed at the intrasubtype level, including two variations of ST1 (ST1A, ST1B), and seven of ST5 (ST5A to ST5G), by sequence alignment analysis and phylogenetic analysis. More studies are needed to elucidate the transmission and public health significance of Blastocystis in pigs in various areas. [ABSTRACT FROM AUTHOR]

Coptotermes formosanus Shiraki and Coptotermes gestroi (Wasmann) (Blattoidea: Rhinotermitidae) are invasive subterranean termite pest species with a major global economic impact. However, the descriptions of the mutualistic protist communities harbored in their respective hindguts remain fragmentary. The C. formosanus hindgut has long been considered to harbor three protist species, Pseudotrichonympha grassii (Trichonymphida), Holomastigotoides hartmanni, and Cononympha (Spirotrichonympha) leidyi (Spirotrichonymphida), but molecular data have suggested that the diversity may be higher. Meanwhile, the C. gestroi community remains undescribed except for Pseudotrichonympha leei. To complete the characterization of these communities, hindguts of workers from both termite species were investigated using single‐cell PCR, microscopy, cell counts, and 18S rRNA amplicon sequencing. The two hosts were found to harbor intriguingly parallel protist communities, each consisting of one Pseudotrichonympha species, two Holomastigotoides species, and two Cononympha species. All protist species were unique to their respective hosts, which last shared a common ancestor ~18 MYA. The relative abundances of protist species in each hindgut differed remarkably between cell count data and 18S rRNA profiles, calling for caution in interpreting species abundances from amplicon data. This study will enable future research in C. formosanus and C. gestroi hybrids, which provide a unique opportunity to study protist community inheritance, compatibility, and potential contribution to hybrid vigor. [ABSTRACT FROM AUTHOR]

On their spore surfaces, Microsporidia often develop a canopy of filaments with characteristics of intermediate filaments (IF), as we demonstrated in previous studies on Thelohania sp., Ameson michaelis, and Spraguea lophii. Genomic studies indicate that among invertebrates, lamins that may localize in the cytoplasm or nucleus, are the only known IF type. These IFs can bind to the substrate containing cell adhesion molecules (CAMs) cadherins, associated with β and γ catenins. The objects of this study were to determine whether microsporidia have CAMs with the attached IFs on their envelopes and to find out if these proteins are provided by the host. An examination was made for localization of lamins and CAMs on the spores of the mentioned above species and Anncaliia algerae, plus in the host animals. Then, we determined whether the spores of A. michaelis and A. algerae could bind vertebrate nuclear lamin onto the spore surface. We also tested transgenic Drosophila melanogaster stocks bearing cadherin‐GFP to see whether developing A. algerae parasites in these hosts could acquire host CAMs. The tests were positive for all these experiments. We hypothesize that microsporidia are able to acquire host lamin IFs and cell adhesion catenin–cadherin complexes from the host. [ABSTRACT FROM AUTHOR]

During the last decade, high‐throughput metabarcoding became routine for analyzing protistan diversity and distributions in nature. Amid a multitude of exciting findings, scientists have also identified and addressed technical and biological limitations, although problems still exist for inference of meaningful taxonomic and ecological knowledge based on short DNA sequences. Given the extensive use of this approach, it is critical to settle our understanding on its strengths and weaknesses and to synthesize up‐to‐date methodological and conceptual trends. This article summarizes key scientific and technical findings, and identifies current and future directions in protist research that uses metabarcoding. [ABSTRACT FROM AUTHOR]

Labyrinthulomycetes are mostly fungus‐like heterotrophic protists that absorb nutrients in an osmotrophic or phagotrophic manner. Members of order Labyrinthulida produce unique membrane‐bound ectoplasmic networks for movement and feeding. Among the various types of labyrinthulids' food substrates, diatoms play an important role due to their ubiquitous distribution and abundant biomass. We isolated and cultivated new diatom consuming Labyrinthulida strains from shallow coastal marine sediments. We described Labyrinthula diatomea n. sp. that differs from all known labyrinthulids in both molecular and morphological features. We provided strain delimitation within the genus Labyrinthula based on ITS sequences via haplotype network construction and compared it with previous phylogenetic surveys. [ABSTRACT FROM AUTHOR]

Microsporidia are known opportunistic microorganisms and usually transmitted via the fecal–oral route. However, there is no information about human‐infecting microsporidia in wildlife in Iran. This study aimed to investigate and analyze human‐infecting microsporidia isolated from raccoons in north of Iran. Totally, 30 fecal samples were collected; then, DNA extraction was performed and specific fragments of the SSU rRNA gene of Enterocytozoon bieneusi and Encephalitozoon species were amplified. After amplification and sequencing the ITS, the results were compared to the GenBank database. Phylogenetic trees and network analysis were employed to explore probable relationships. E. bieneusi was the only detected microsporidia among samples. Genotyping showed the genotypes D, E, and RA in 15/18 (83.33%), 1/18 (5.55%), and 2/18 (11.11%) of samples, respectively. Novel genotypes RA1 and RA2 grouped together and apart from other genotypes. E. bieneusi genotypes D and E clustered with the genotypes previously reported from animals, humans, and environmental samples. Network analysis revealed six distinct sequence types among raccoon's isolates. This study demonstrated that E. bieneusi genotype D was the most prevalent microsporidia among raccoons. It seems that wildlife may play a role in dispersion of microsporidia spores. [ABSTRACT FROM AUTHOR]

Myxomycetes (also called Myxogastria or colloquially, slime molds) are worldwide occurring soil amoeboflagellates. Among Amoebozoa, they have the notable characteristic to form, during their life cycle, macroscopic fruiting bodies, that will ultimately release spores. Some 1,000 species have been described, based on the macroscopic and microscopic characteristics of their fruiting bodies. We were interested in Physarum pusillum (Berk. & M.A. Curtis) G. Lister, a very common species described with two variants, each bearing such morphological differences that they could represent two distinct species. In order to test this, we observed key characters in a large selection of specimens attributed to P. pusillum, to its synonyms (in particular Physarum gravidum), and to related species. In addition, the small‐subunit ribosomal RNA gene was obtained from seven of these specimens. Based on these data, we provide a comprehensive phylogeny of the order Physarida (Eukaryota: Amoebozoa: Conosa: Macromycetozoa: Fuscisporidia). Morphology and phylogeny together support the reinstatement of P. gravidum Morgan 1896 with a neotype here designated, distinct from P. pusillum, here redefined. [ABSTRACT FROM AUTHOR]

We have obtained a sequence of the 18S rRNA gene of the species Polychaos annulatum (Penard 1902) Smirnov et Goodkov 1998 using the isolation of a single nucleus from an amoeba cell. Attempts to amplify the 18S rRNA gene from the DNA of this species by conventional PCR were not successful, so we applied the whole genome amplification of the nuclear DNA followed by NGS sequencing. The 18S rRNA gene was found among the resulting contigs. The analysis unexpectedly shows that P. annulatum robustly groups within the family Hartmannellidae, but not Amoebidae. This finding warrants revision of the basic morphological criteria used to classify Euamoebida families and show that "proteus‐type" amoebae may belong to other families rather than Amoebidae. This makes taxonomic assignments of such species more complex and the borders between Euamoebida families more nuanced. It is getting evident that molecular data are necessary to clarify the position of species even in this most "classical" order of naked lobose amoebae. [ABSTRACT FROM AUTHOR]

Pleurostomatida Schewiakoff, 1896 is a cosmopolitan order of ciliates. In the present study, we investigated two new pleurostomatid species, Apolitonotus lynni gen. et sp. nov. and Protolitonotus clampi sp. nov., with state‐of‐the‐art methods. Apolitonotus lynni lacks its oral extrusomes and its right kineties form an anterior semi‐suture near the dorsal margin. Based on these two features, the new genus Apolitonotus was established within the Protolitonotidae Wu et al., 2017. Protolitonotus clampi differs from its congeners by its size of 80–130 × 15–30 μm, 4–6 left, and 9–11 right kineties, extrusomes arranged along the oral slit, and two macronuclear nodules. Because Litonotus antarcticus possesses an anterior semi‐suture and oral extrusomes, it was transferred to the genus Protolitonotus, becoming P. antarctius comb. nov. (basionym Litonotus antarcticus Song and Wilbert, 2002). Phylogenetic analyses based on SSU rDNA sequences suggest a sister group relationship of P. clampi and the family Kentrophyllidae, and A. lynni is adelphotaxon to Litonotus gracilis, both within the order Pleurostomatida. Based on the new findings, an improved diagnosis for Protolitonotus was also provided. [ABSTRACT FROM AUTHOR]

The morphology of two oligotrich ciliates, Pelagostrombidium fallax (Zacharias, 1895) Krainer, 1991 and Limnostrombidium viride (Stein, 1867) Krainer, 1995, collected from a freshwater pond in northern China, was studied based on live observation and protargol staining. Currently, undescribed features in the girdle kinety in P. fallax are (a) sparsely spaced single argyrophilic basal bodies in the shoulder region and (b) a U‐shape formed below the buccal peristome. An improved diagnosis for P. fallax is supplied, based on previous and present morphological descriptions. In addition, certain ontogenetic stages of P. fallax are reported for the first time. During division, two new embryonic bodies are successively generated de novo, the first one goes to the proter, the second one to the opisthe; the new canal derives from the old canal. The morphology of L. viride is redescribed in detail; the Chinese population is highly consistent with populations in Europe. The SSU rRNA gene of P. fallax was sequenced for the first time. Phylogenetic analyses, based on SSU rRNA gene sequence data, reveal that P. fallax and L. viride cluster with Strombidium species while the result of an AU test did not reject the possibility of monophyly of the family Pelagostrombidiidae. [ABSTRACT FROM AUTHOR]

The diversity of centrohelids in inland saline waters was studied with metabarcoding for the first time. The fragment of V6–V7 regions of 18S rDNA was sequenced with newly designed primers. Obtained OTUs were identified with molecular phylogenetic analysis and comparison of the signatures in 39es9 hairpin of V7. The obtained data included some OTUs, which could be attributed to four described species, but the majority belonged to previously established or novel environmental clades. Along with some presumably marine/brackish clades and freshwater/low salinity (0–2 ppt) clades, seven presumable species demonstrating broad (from 1–2 up to 78 ppt) salinity tolerance were detected. A number of OTUs belonged to Raphidocystis contractilis, which is known from three independent findings in brackish habitats only. Thus, it was assumed that this species is stenohaline and specifically adapted to salinity 5–15 ppt. The high level of salinity tolerance was suggested for centrohelids before based on morphology, which was used to justify their cosmopolitan distribution. Later these views were criticized based on environmental sequencing, but the results of the current survey indicate, that at least some species are present at salinities from almost freshwater (1–2 ppt) to twice oceanic (78 ppt) and are presumably capable of overcoming oceanic salinity barriers for their distribution. [ABSTRACT FROM AUTHOR]

Ciliated protists have attracted wide interest among researchers from the Indian subcontinent in the last few years. An International Symposium on Ciliate Biology (ISCB) 2018 was held on 04–06 April 2018 at the India Habitat Centre, New Delhi, India. The symposium represented a synergy with International Research Coordination Network for Biodiversity of Ciliates (IRCN‐BC), an affiliate society of International Society of Protistologists (ISOP). The symposium provided a platform for Indian and International delegates to exchange knowledge, present their latest research findings, and establish collaborations as well as creating a networking opportunity for undergraduate and postgraduate students. Nine foreign delegates from 5 countries and 300 Indian delegates actively participated in the event which included 22 oral and 57 poster presentations. [ABSTRACT FROM AUTHOR]

Grazing behaviour between protozoa and phytoplankton exists widely in planktonic ecosystems. Poterioochromonas malhamensis is a well‐known and widespread mixotrophic flagellate, which is recognized to play an important role within marine and freshwater planktonic ecosystems and regarded as the greatest contamination threat for mass algal cultures of Chlorella. In this study, a comprehensive range of factors, including morphological characters, biochemical compositions, and specific growth rate of ten species or strains of Chlorella, were evaluated for their effect on the feeding ability of P. malhamensis, which was assessed by two parameters: the clearance rate of P. malhamensis on Chlorella spp. and the specific growth rate of P. malhamensis. The results showed that the clearance rate of P. malhamensis was negatively correlated with cell wall thickness and specific growth rate of Chlorella spp., while the specific growth rate of P. malhamensis was positively correlated with carbohydrate percentage and C/N ratio and negatively correlated with protein, lipid percentage, and nitrogen mass. In conclusion, the factors influencing feeding selectivity include not only the morphological character and chemical composition of Chlorella, but also its population dynamics. Our study provides useful insights into the key factors that affect the feeding selectivity of P. malhamensis and provides basic and constructive data to help in screening for grazing‐resistant microalgae. [ABSTRACT FROM AUTHOR]

Only a limited number of studies exist on the life cycles of nonmodel ciliates such as Chilodonella uncinata (Cl: Phyllopharyngea). The handful of papers on this taxon indicate the presence of a heteromeric macronucleus, marked by separate DNA-rich and DNA-poor regions. Here, we study the life cycle of C. uncinata using confocal laser scanning microscopy with 4′,6-diamidino-2-phenylindole staining, which allows us to differentiate nuclear dynamics of the micronucleus and the macronucleus during life-cycle stages. We photo-documented various stages and confirmed aspects of the development of the new macronucleus previously characterized by electron microscopy. We further reveal the heteromeric structure of the macronucleus with Z-stacks and three-dimensional (3D) reconstructions. We find no evidence for the presence of an endosome at the center of the macronucleus during vegetative growth. In addition to illustrating the life cycle of this ciliate, the approaches developed for this study will enable additional comparative analyses of nuclear dynamics using fluorescence microscopy. [ABSTRACT FROM AUTHOR]

An obituary for ciliate geneticist David L. Nanney is presented.

Based on both morphological and molecular information, two new euplotid genera Apodiophrys n. g. and Heterodiophrys n. g. are described in the present paper. Apodiophrys n. g. is defined as sculptured Diophryinae with bipartite adoral zone; frontoventral cirri arranged in Diophrys-pattern; marginal cirri located in two clearly separated groups. Heterodiophrys n. g. is recognizable by the combination of Diophrys-like frontoventral cirri and the unique structure of several marginal cirri that are arranged in a long row. The type species for both new genera, Apodiophrys ovalis n. sp. and Heterodiophrys zhui n. sp., collected from southern China sea, are described. The small subunit rRNA (SSU rRNA) gene sequences for both new taxa are determined. Phylogenetic analyses based on these data indicate that Apodiophrys is most closely related to Paradiophrys, which then clusters with Uronychia species. Thus, Apodiophrys–Paradiophrys is separated from other typical Diophrys-like genera in the SSU rRNA gene trees. The new genus Heterodiophrys is basal to the sister group of Diophrys–Diophryopsis, hence belongs to the “core” Diophrys-complex. [ABSTRACT FROM AUTHOR]

Our knowledge of the diversity of amoeboid protists is rapidly expanding as new and old habitats are more fully explored. In 2003, while investigating the cause of an amoeboid disease afflicting lobsters on the East Coast, samples were examined for the presence of amoebae from the carapace washings of the American lobster, Homarus americanus. During this survey a unique community of gymnamoebae was discovered. Among the new taxa discovered was a small Thecamoeba-like organism with a single posteriorly directed pseudopodium. Although resembling Parvamoeba rugata, this amoeba displayed distinctive morphology from that isolate or any other amoebozoan. Phylogenetic analysis shows this amoeba is distantly related to the Thecamoebidae. In this paper we describe the unique morphology of a second species of Parvamoeba and discuss its phylogenetic position with respect to the “Amoebozoa.” [ABSTRACT FROM AUTHOR]

The diatom genera Licmophora and Fragilaria are frequent epiphytes on marine macroalgae and can be infected by intracellular parasitoids traditionally assigned to the oomycete genus Ectrogella. Much debate and uncertainty remains about the taxonomy of these oomycetes, not least due to their morphological and developmental plasticity. Here, we used single‐cell techniques to obtain partial sequences of the parasitoids 18S and cox2 genes. The former falls into two recently identified clades of Pseudo‐nitzschia parasites temporarily named OOM_1_2 and OOM_2, closely related to the genera of brown and red algal pathogens Anisolpidium and Olpidiopsis. A third group of sequences falls at the base of the red algal parasites assigned to Olpidiopsis. In one instance, two oomycete parasitoids seemed to co‐exist in a single diatom cell; this co‐occurrence of distinct parasitoid taxa not only within a population of diatom epiphytes, but also within the same host cell, possibly explains the ongoing confusion in the taxonomy of these parasitoids. We demonstrate the polyphyly of Licmophora parasitoids previously assigned to Ectrogella (sensu Sparrow, 1960) and show that parasites of red algae assigned to the genus Olpidiopsis are most likely not monophyletic. We conclude that combining single‐cell microscopy and molecular methods is necessary for their full characterisation. [ABSTRACT FROM AUTHOR]

Eugregarines are understudied apicomplexan parasites of invertebrates inhabiting marine, freshwater, and terrestrial environments. Most currently known terrestrial eugregarines have been described parasitizing the gut from less than 1% of total insect diversity, with a high likelihood that the remaining insect species are infected. Eugregarine diversity in orthopterans (grasshoppers, locusts, katydids, and crickets) is still little known. We carried out a survey of the eugregarines parasitizing the Mexican lubber grasshopper, Taeniopoda centurio, an endemic species to the northwest of Mexico. We described two new eugregarine species from the gut of the host: Amoebogregarina taeniopoda n. sp. and Quadruspinospora mexicana n. sp. Both species are morphologically dissimilar in their life‐cycle stages. Our SSU rDNA phylogenetic analysis showed that both species are phylogenetically distant to each other, even though they parasitize the same host. Amoebogregarina taeniopoda n. sp. clustered within the clade Gregarinoidea, being closely related to Amoebogregarina nigra from the grasshopper Melanoplus differentialis. Quadruspinospora mexicana n. sp. clustered within the clade Actinocephaloidea and grouped with Prismatospora evansi, a parasite from dragonfly naiads. Amoebogregarina taeniopoda n. sp. and Q. mexicana n. sp. represent the first record of eugregarines found to infect a species of the family Romaleidae. [ABSTRACT FROM AUTHOR]

A new marine species of naked lobose amoebae Pseudoparamoeba garorimi n. sp. (Amoebozoa, Dactylopodida) isolated from intertidal marine sediments of Garorim Bay, Korea was studied with light and transmission electron microscopy. This species has a typical set of morphological characters for a genus including the shape of the locomotive form, type of subpseudopodia and the tendency to form the single long waving pseudopodium in locomotion. Furthermore, it has the same cell surface structures as were described for the type species, Pseudoparamoeba pagei: blister‐like glycostyles with hexagonal base and dome‐shaped apex; besides, cell surface bears hair‐like outgrowths. The new species described here lacks clear morphological distinctions from the two other Pseudoparamoeba species, but has considerable differences in the 18S rDNA and COX1 gene sequences. Phylogenetic analysis based on 18S rDNA placed P. garorimi n. sp. at the base of the Pseudoparamoeba clade with high PP/BS support. The level of COX1 sequence divergence was 22% between P. garorimi n. sp. and P. pagei and 25% between P. garorimi n. sp. and P. microlepis. Pseudoparamoeba species are hardly distinguishable by morphology alone, but display clear differences in 18S rDNA and COX1 gene sequences. [ABSTRACT FROM AUTHOR]

In the present study, fecal samples from a total of 620 Tibetan sheep and 260 Tibetan goats from six counties in Tibet were examined by nested PCR. The results showed that the overall infection rates of Giardia duodenalis and Enterocytozoon bieneusi were 0.8% (5/620) and 15% (93/620), respectively, in Tibetan sheep, and 0% (0/260) and 9.6% (25/260), respectively, in Tibetan goats. Based on sequence analysis of the SSU rRNA, tpi, bg, and gdh genes of G. duodenalis, only assemblage E was identified. Based on sequence analysis of the ribosomal internal transcriptional spacer (ITS) region of E. bieneusi, a total of 12 genotypes (three novel and nine known) were detected, and these clustered into two separate phylogenetic groups. Genotypes CHG19, EbpA, EbpC, H, PigEBITS5, and CTS3 clustered into Group 1 with high zoonotic potential, while genotypes BEB6, CHC8, CHG1, I, CTS1, and CTS2 fell within the host‐specific Group 2. Ten genotypes were detected in Tibetan sheep, and two genotypes were found in Tibetan goats. The current study indicated that E. bieneusi infections are widespread among these livestock, and Tibetan goats may play an important role as a reservoir of zoonotic E. bieneusi genotypes. [ABSTRACT FROM AUTHOR]

Reclamation of anthropogenically impacted environments is a critical issue worldwide. In the oil sands extraction industry of Alberta, reclamation of mining‐impacted areas, especially areas affected by tailings waste, is an important aspect of the mining life cycle. A reclamation technique currently under study is water‐capping, where tailings are capped by water to create an end‐pit lake (EPL). Base Mine Lake (BML) is the first full‐scale end‐pit lake in the Alberta oil sands region. In this study, we sequenced eukaryotic 18S rRNA genes recovered from 92 samples of Base Mine Lake water in a comprehensive sampling programme covering the ice‐free period of 2015. The 565 operational taxonomic units (OTUs) generated revealed a dynamic and diverse community including abundant Microsporidia, Ciliata and Cercozoa, though 41% of OTUs were not classifiable below the phylum level by comparison to 18S rRNA databases. Phylogenetic analysis of five heterotrophic phyla (Cercozoa, Fungi, Ciliata, Amoebozoa and Excavata) revealed substantial novel diversity, with many clusters of OTUs that were more similar to each other than to any reference sequence. All of these groups are entirely or mostly heterotrophic, as a relatively small number of definitively photosynthetic clades were amplified from the BML samples. [ABSTRACT FROM AUTHOR]

A new genus and species of centrohelid heliozoan Pinjata ruminata from the Tuzlukkol' River (Orenburg Region of Russia) and Gorʼkoe Lake (Chelyabinsk Region of Russia) is studied with light‐ and electron microscopy. Pinjata ruminata has two types of plate scales, partially running up the sides of the axopodia. Inner plate scales (3.2–4.9 × 1.5–2.6 μm) are flat, ovate‐oblong and have a broad axial thickening and a thin electron‐dense border. Outer plate scales (4.2–6.7 × 1.5–3.0 μm) are concave, elongated, of irregular shape, often curved, and broadened towards one end. Roundish depressions are forming two rows on both sides of the narrow axial thickening. The cells are attached to the substratum. Molecular phylogenetic analysis based on the SSU rDNA robustly placed P. ruminata in the family Yogsothothidae. This position is confirmed with the presence of five panacanthocystid increase regions. The morphology of the new genus is in a good accordance with diagnosis of the family. The status of a genus "Heteroraphidiophrys" is discussed. Other potential findings of Pinjata from literature are analyzed. Pinjata represents the third lineage of centrohelids, characterized with the presence of only tangentially oriented plate scales. The halophilic nature of Yogsothothidae is suggested. [ABSTRACT FROM AUTHOR]

Holomastigotes is a protist genus (Parabasalia: Spirotrichonymphea) that resides in the hindguts of "lower" termites. It can be distinguished from other parabasalids by spiral flagellar bands that run along the entire length of the cell, an anterior nucleus, a reduced or absent axostyle, the presence of spherical vesicles inside the cells, and the absence of ingested wood particles. Eight species have been described based on their morphology so far, although no molecular data were available prior to this study. We determined the 18S rRNA gene sequences of Holomastigotes from the hindguts of Hodotermopsis sjostedti, Reticulitermes flavipes, Reticulitermes lucifugus, and Reticulitermes tibialis. Phylogenetic analyses placed all sequences in an exclusive and well‐supported clade with the type species, Holomastigotes elongatum from R. lucifugus. However, the phylogenetic position of Holomastigotes within the Spirotrichonymphea was not resolved. We describe two new species, Holomastigotes flavipes n. sp. and Holomastigotes tibialis n. sp., inhabiting the hindguts of R. flavipes and R. tibialis, respectively. [ABSTRACT FROM AUTHOR]

The deep sea has long been a mysterious and attractive habitat for protistologists. However, logistical difficulties severely limit sampling opportunities. Consequently, our knowledge of the protists in the deep sea, (arguably the largest habitat on earth), is relatively sparse. Here, we present a unique time‐series concerning three different protist taxa that share only the characteristics of being relatively large, robust to sampling, and easily identifiable to species level using light microscopy: tintinnid ciliates, phaeogromid cercozoans (e.g. Challengerids) and amphisolenid dinoflagellates. We sampled a near‐shore deep water site in the N.W. Mediterranean Sea at 250 m depth over a 2‐yr period at approximately weekly intervals from January 2017 to December 2018. To our knowledge, no previous studies have employed sampling on a similar time scale. We found taxa that appear to be restricted to deep waters, distinct seasonal patterns of abundance in some taxa, and in others nonseasonal successional patterns. Based on data from sampling following a flash flood event, the Challengerid population appeared to respond positively to a pulse of terrigenous input. Some of the distinct mesopelagic tintinnid ciliates and amphisolinid dinoflagellates were also found in two samples from the North Atlantic mesopelagic gathered from near the Azores Islands in September 2018. We conclude that there are a variety of protist taxa endemic to the mesopelagic, that the populations are dynamic, and they may be widely distributed in the deep waters of the world ocean. [ABSTRACT FROM AUTHOR]

Fungi encompass, in addition to classically well‐studied lineages, an ever‐expanding diversity of poorly known lineages that include, among others, zoosporic chytrid‐like parasites. According to recent phylogenetic analysis based on 18S + 28S rRNA concatenated genes two unusual chytrid‐like fungi Amoeboradix gromovi and Sanchytrium tribonematis form a monophyletic group, the family Sanchytriaceae, which represents a new divergent taxon that remains incertae sedis within Fungi. Zoospores of Amoeboradix gromovi contain one of the longest kinetosomes known in eukaryotic cells, which are composed of microtubular singlets or doublets. However, the ultrastructure of S. tribonematis, the type species of the genus had not been yet studied. Here, we provide the results of TEM investigations of zoospores and sporangia from two strains of S. tribonematis. The two strains are endowed with unusual features. Like in A. gromovi, amoeboid zoospores of S. tribonematis contain a long kinetosome composed of microtubular singlets, and the two orthogonal centrioles in their sporangia have nine microtubular singlets with an internal ring. The morphological and ultrastructural features of S. tribonematis are now included in the improved taxonomic diagnosis for this species. [ABSTRACT FROM AUTHOR]

The enzymes pyruvate ferredoxin oxidoreductase (PFO), malic enzyme (ME), and the α‐ and β‐subunits of succinyl‐CoA synthetase (SCS) catalyze key steps of energy metabolism in Trichomonas vaginalis hydrogenosomes. These proteins have also been characterized as the adhesins AP120 (PFO), AP65 (ME), AP33, and AP51 (α‐ and β‐SCS), which are localized on the cell surface and mediate the T. vaginalis cytoadherence. However, the mechanisms that facilitate the targeting of these proteins to the cell surface via the secretory pathway and/or to hydrogenosomes are not known. Here we adapted an in vivo biotinylation system to perform highly sensitive tracing of protein trafficking in T. vaginalis. We showed that α‐ and β‐SCS are biotinylated in the cytosol and imported exclusively into the hydrogenosomes. Neither α‐ nor β‐SCS is biotinylated in the endoplasmic reticulum and delivered to the cell surface via the secretory pathway. In contrast, two surface proteins, tetratricopeptide domain‐containing membrane‐associated protein and tetraspanin family surface protein, as well as soluble‐secreted β‐amylase‐1 are biotinylated in the endoplasmic reticulum and delivered through the secretory pathway to their final destinations. Taken together, these results demonstrate that the α‐ and β‐SCS subunits are targeted only to the hydrogenosomes, which argues against their putative moonlighting function. [ABSTRACT FROM AUTHOR]

Myxomycetes (plasmodial slime molds) are abundant protist predators that feed on bacteria and other microorganisms, thereby playing important roles in terrestrial nutrient cycling. Despite their significance, little is known about myxomycete communities and the extent to which they are affected by nutrient availability. We studied the influence of long‐term addition of N, P, and K on the myxomycete community in a lowland forest in the Republic of Panama. In a previous study, microbial biomass increased with P but not N or K addition at this site. We hypothesized that myxomycetes would increase in abundance in response to P but that they would not respond to the sole addition of N or K. Moist chamber cultures of leaf litter and small woody debris were used to quantify myxomycete abundance. We generated the largest myxomycete dataset (3,381 records) for any single locality in the tropics comprised by 91 morphospecies. In line with our hypothesis, myxomycete abundance increased in response to P addition but did not respond to N or K. Community composition was unaffected by nutrient treatments. This work represents one of very few large‐scale and long‐term field studies to include a heterotrophic protist highlighting the feasibility and value in doing so. [ABSTRACT FROM AUTHOR]

A new hypotrichous ciliate, Schmidtiella ultrahalophila gen. nov., spec. nov., was isolated from a solar saltern on the island of Sal, Cape Verde. The possession of only one short dorsal kinety clearly distinguishes S. ultrahalophila from other known hypotrichous genera and species. Further diagnostic characters include: a flexible and slender body, an average size of 85 × 15 μm in vivo; a bipartite adoral zone with two hypertrophied frontal adoral membranelles and nine to twelve ventral adoral membranelles; three frontal, one parabuccal, two frontoventral, two or three postoral ventral, and two or three frontoterminal cirri; and marginal cirral rows variable in number, usually one on each side. Ontogenetic data indicate the following: the frontal‐ventral cirri originate from six or five anlagen; the proter inherits the parental adoral zone; the frontal and ventral cirri originate from five or six anlagen; and the marginal cirral rows and the dorsal kinety tend to originate intrakinetally. Additional marginal rows are rarely derived from de novo anlagen. Based on its morphology, morphogenesis and its SSU rRNA phylogenetic placement, the new species should be assigned to the order Sporadotrichida Fauré‐Fremiet, 1961. Due to low taxon sampling, however, its exact position in this order remains enigmatic. [ABSTRACT FROM AUTHOR]

Pathogenicity, evolutionary history, and unusual cell organization of diplomonads are well known, particularly for Giardia and Spironucleus; however, behavior of these aerotolerant anaerobes is largely unknown. Addressing this deficit, we studied behavior of the piscine diplomonad Spironucleus vortens (ATCC 50386) in in vitro culture. Spironucleus vortens trophozoites from Angelfish, Pterophyllum scalare, were maintained axenically in modified liver digest, yeast extract, and iron (LYI) medium, at 22 °C in the dark, and subcultured weekly. Cultures were monitored every 1–2 d, by removing an aliquot, and loading cells into a hemocytometer chamber, or onto a regular microscope slide. We observed three distinct swimming behaviors: (i) spontaneous formation of swarms, reaching 200 μm in diameter, persisting for up to several min in situ, (ii) directional movement of the swarm, via collective motility, and (iii) independent swimming of trophozoites to form a band (aggregation), presumably at the location of optimal environmental conditions. These behaviors have not previously been reported in Spironucleus. The observation that flagellate motility can change, from individual self‐propulsion to complex collective swarming motility, prompts us to advocate S. vortens as a new model for study of group behavioral dynamics, complementing emerging studies of collective swimming in flagellated bacteria. [ABSTRACT FROM AUTHOR]

Chorthippus loratus collected in Krasnodar Territory in 2017 was infected at 15% rate with a microsporidium possessing ovocylindrical binucleate spores, 2.6 × 1.2 μm in size. SSU RNA gene typing (Genbank accession # MH396491) showed its allocation to the genus Liebermannia. Degenerate primers based upon largest subunit RNA polymerase II (RPB1) sequences of closest relatives allowed amplifying the respective gene fragment of Liebermannia sp. (# MH396492). The present finding indicates worldwide distribution of the Liebermannia genus and parasitism in hosts with nonoverlapping geographic ranges (representing Neotropical versus Palearctic fauna), while previous observations were restricted to Acridoidea endemic for South America. [ABSTRACT FROM AUTHOR]