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Harmful algal blooms (HABs) have severe environmental and economic impacts worldwide. Improving HAB detection is crucial because massive blooms are likely to increase in both frequency and amplitude in the next decades due to global warming and escalating coastal eutrophication. While satellite remote sensing has proved useful to detect red tides and support HAB monitoring, the discrimination of the dominant bloom-forming species is still a challenge, all the more as the observation of highly concentrated phytoplankton patches can be hampered by a too coarse spatial resolution. Moreover, the majority of HAB studies generally had a regional focus, and a limited number of species were separately documented so far. Here, we provide a broader perspective for red tides remote sensing to better resolve HAB optical and taxonomical diversity. The main objective of the present study was to identify how many optical bloom types could be recognized with the high spatial resolution Sentinel-2 (S2) satellite mission. For that purpose, an extensive database of massive, nearly monospecific blooms, both documented in situ and using synchronous S2 observation was compiled. More than 100 S2 images of various red tides were selected worldwide. Altogether, the S2 database covered the typical reflectance spectra of 27 red tide forming species. The remote-sensing reflectance of each red tide was analysed to evaluate S2 ability to distinguish the dominant species of the bloom. A hierarchical clustering analysis suggested that six optical bloom types could be identified: (1) surface accumulation of cyanobacteria or of green Noctiluca scintillans, (2) surface accumulation of red N. scintillans (a purely heterotrophic plankton devoid of chlorophyll a), (3) red tides of Mesodinium rubrum (a phycoerythrin-bearing ciliate), (4) green seawater discolorations of Lepidodinium chlorophorum (a dinoflagellate with unusual carotenoids), (5) blooms dominated by a dinoflagellate such as Prorocentrum, Gymnodinium, Lingulodinium polyedra, Gonyaulax or Alexandrium, and (6) brown tides dominated by a dinoflagellate (such as Karenia, Karlodinium veneficum, Protoceratium reticulatum, Margalefidinium polykrikoides, or Tripos fusus), a prymnesiophyte (Phaeocystis), or a pelagophyte (Aureococcus anophagefferens). While the results presented here are inherently limited by the concomitant availability of in situ and S2 observations, as well as by S2 spectral resolution, it is a step forward to an improved understanding of HAB bio-optical diversity.

Entodinium caudatum is an anaerobic binucleated ciliate representing the most dominant protozoal species in the rumen. However, its biological features are largely unknown due to the inability to establish an axenic culture. In this study, we primally sequenced its macronucleus (MAC) genome to aid the understanding of its metabolism, physiology, ecology. We isolated the MAC of E. caudatum strain MZG-1 and sequenced the MAC genome using Illumina MiSeq, MinION, and PacBio RSII systems. De novo assembly of the MiSeq sequence reads followed with subsequent scaffolding with MinION and PacBio reads resulted in a draft MAC genome about 117 Mbp. A large number of carbohydrate-active enzymes were likely acquired through horizontal gene transfer. About 8.74% of the E. caudatum predicted proteome was predicted as proteases. The MAC genome of E. caudatum will help better understand its important roles in rumen carbohydrate metabolism, and interaction with other members of the rumen microbiome.

Algal palynomorphs are useful indicators of freshwater environments in the past and present, allowing reconstruction of such environmental characteristics as former pH, trophic stage, temperature and salinity. However, the using of algal palynomorphs in paleoecology is restricted by their resistance to natural degradation and acetolysis treatment. In this study, we evaluate the usefulness of the loricate euglenophyte genera Trachelomonas and Strombomonas as paleoecological indicators. In order to evaluate their resistance to degradation, loricae morphology of four Trachelomonas species from the Culture Collection of Algae at Gottingen University (SAG) were studied with and without acetolysis treatment. The experiment demonstrates a strong dissolution under acetolysis of the three species T. hispida , T. lefevrei , T. zorensis and a reduction in the loricae length by T. similis . In the Holocene records, Trachelomonas can be found in non-acetolyzed samples, occurring together with other eutrophication indicators such as cyanobacteria and ciliate Codonella cratera . A review of recent algological literature supports Trachelomonas being a good indicator of organic pollution.

In September 2020 when we were investigating about opportunistic free living amoeba in patients with meningitis in Thi –Qar province south of Iraq, throughout examination the CSF which was cultured on NN Agar medium. It was surprisingly we found the ciliates protozoa (Orchitophryidae) in both stages, vegetative and cystic, after that the ciliates were isolated and cultured in vitro and then morphological, molecular and virulence characterizations were studies. The results of morphological study revealed that these ciliates were similar to Mesanophrys sp. whereas the sequence of rDNA of studied ciliate with accession numbers being given. in NCBI LC621170.1 was show (86.04%) homology identity to Mesanophrys sp. 18S rRNA gene (accession number MN260367.1). but show (98.56%) and (97.92%) homology identity to Orchitophrydiae 18S rRNA gene (accession number EF023919.1 and EF023549.1), that may be this ciliates in our study is a new species for Mesanophrys. In addition experimental infection confirmed that Mesanophrys like ciliates was the pathogen that infected human. In summary this study represent the first record of the ciliophora Orchitophryidae (Mesanophrys like ciliates) as a human pathogen from Thi-Qar province / Iraq.

This is the accepted manuscript of the following article: Folgueira I, Lamas J, De Felipe AP, Sueiro RA, Leiro JM. (2019). Evidence for the role of extrusomes in evading attack by the host immune system in a scuticociliate parasite. Fish Shellfish Immunol. 2019 Jul 5;92:802-812. doi: 10.1016/j.fsi.2019.07.008 Like other ciliates, Philasterides dicentrarchi, the scuticociliate parasite of turbot, produces a feeding-only or growing stage called a trophont during its life cycle. Exposure of the trophonts to heat-inactivated serum extracted from the turbot host and containing specific antibodies that induce agglutination/immobilization leads to the production of a mucoid capsule from which the trophonts later emerge. We investigated how these capsules are generated, observing that the mechanism was associated with the process of exocytosis involved in the release of a matrix material from the extrusomes. The extruded material contains mucin-like glycoproteins that were deposited on the surface of the cell and whose expression increased with time of exposure to the heat-inactivated immune serum, at both protein expression and gene expression levels. Stimulation of the trophonts with the immune serum also caused an increase in discharge of the intracellular storage compartments of calcium necessary for the exocytosis processes in the extrusomes. The results obtained suggest that P. dicentrarchi uses the extrusion mechanism to generate a physical barrier protecting the ciliate from attack by soluble factors of the host immune system. Data on the proteins involved and the potential development of molecules that interfere with this exocytic process could contribute to improving the prevention and control of scuticociliatosis in turbot This study was financially supported by grants from the Ministerio de Economía y Competitividad and Fondo Europeo de Desarrollo Regional -FEDER- (European Union) (AGL2017-83577-R) and from the Xunta de Galicia (ED431C2017/31) and also by the PARAFISHCONTROL project, which received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 634429 SI

Microzooplankton communities in the coastal Gulf of Alaska (CGOA) were studied during two contrasting years: 2011, with a greatly reduced spring phytoplankton bloom, and 2013, with a robust spring bloom. Other sampling contrasts were season (spring, summer, fall) and region (eastern versus western shelf waters). Ciliates and dinoflagellates comprised nearly all microzooplankton in the ≥ 15 µm size class. Many of the strongest contrasts in the biomass and taxonomic composition of the microzooplankton community were regional. The east had generally lower microzooplankton biomass levels and a greater proportion of ciliates than the west, even in the face of basin-wide seasonal and interannual contrasts. This difference is likely a consequence of the narrower shelf in the east, which leads to a lower productivity environment. Interannual differences in spring bloom intensity were reflected in microzooplankton biomass (higher in spring 2013, especially in the east), while interannual differences in taxonomic composition persisted throughout the year, with a greater representation of ciliates in 2011. Ciliate dominance could reflect adaptations to lower productivity conditions, with many of the largest taxa likely retaining chloroplasts as a strategy (mixotrophy) for survival during times of prey scarcity. Microzooplankton: phytoplankton biomass ratios varied widely over time and space. These ratios indicate that lower productivity regions (east) and seasons (summer) also tend to be locations and times of reduced trophic transfer efficiency from phytoplankton to ciliates and dinoflagellates. Ciliates and dinoflagellates can be preferred prey of mesozooplankton, including dominant CGOA copepod species. Thus multiple mechanisms conspire to reduce the flow of matter and energy to higher trophic levels in low productivity locations and time periods in the CGOA.

Many protists form cell colonies. Among them several are filter-feeders depending on suspended food particles such as bacteria. It has been suggested that the formation of colonies enhances feeding efficiency and implied that - in the case of colonial choanoflagellates - it was an adaptive trait that led to the evolution of metazoans. Here it is shown experimentally - for a colonial peritrich ciliate and for a choanoflagellate - that colony-formation does not enhance the efficiency of filter-feeding relative to solitary cells and that the adaptive significance of cell colony-formation must have some other explanation.

According to the currently developed Koln–Model based on Hydractinia echinata Test–System (HeTS), the methodical toxicity investigations conducted with amphiphilic and non–amphiphilic singular derivatives with homo– and heteronomous segmentation from 20 different classes, reveals that the effectiveness noted M (mol/L) are characteristic for the Aromatic Basis of Toxicity (ABT) model, for the Class Regular–Increased Toxicity (CRIT) and for Class Iso–Toxicity (CIT), respectively. The phenomenon of toxicity is the result of monovalent interaction between the larval cellular receptor (R) of the marine colonial hydroid H. echinata organism and the xenobiotic substrate (SbX) with the molecular aggregate transitional–complex (RSbX) formation and the information–signal generation (SI), according to the Dual Causality Principle that biological phenomena are simultaneously determined by genetic programs and physics laws. The SI consists of chemical (SIch) and electromagnetic (SIem) components, and is directly responsible for the simultaneous onset of the metamorphosis quantified by the M toxicity values and the metabolizing process of the SbX, with the formation of the reaction products (P). The CRIT, respectively CIT approach was also successfully applied to published data obtained with the ciliate protozoan Tetrahymena pyriformis (T. pyriformis), the freshwater fish Pimephales promelas (P. promelas), the freshwater crustacean Daphnia magna (D. magna) and the marine bacterium Vibrio fischeri (name Aliivibrio fischeri) test–systems (TS’s).

The endophytic bacterial community of two hyperaccumulators (Arabis alpine, Dysphania ambrosioides) and Veronica ciliate was investigated by Illumina sequencing technology. In addition, the culturable endophytic bacteria (EB) were isolated and their plant-growth promotion capabilities were studied. A dataset consisting of 221,075 filtered high-quality and classifiable unique 16S rDNA gene tags, and an average of 36,846 tags with a mean length of 464-bp for each sample was generated. In total, 10801 different operational taxonomic units (OTUs) were detected, belonging to 18 bacterial phyla, 41 classes, 91 orders, 135 families, and 215 genera. Pseudomonas was the most dominant genus in both shoots and roots of the two hyperaccumulators, making up 81.56% and 81.13%, 41.60% and 77.06% of the total number of OTUs, respectively. However, both Chao 1 and Shannon indices of EB of the two hyperaccumulators were significantly lower than those of V. ciliate (P. 05), except the Shannon index of D. ambrosioides shoots. The endophytic bacterial community of roots and shoots of A. alpine showed greater similarity with that of D. ambrosioides roots (12 km away), and clustered to one group in dendrogram, in clear contrast to that of V. ciliate, which grew closer to A. alpine (60 m away). Combining results of soil and plant analyses, we suggest that the soil properties, especially heavy metal concentration, may influence the plants endophytic bacterial community composition. Pot experiments showed that the strain BXGe71 (Microbacterium sp.) from A. alpine significantly enhanced host plants' growth under multi-heavy metal (HM) stress (P .05, t-test).

A novel hypotrichous ciliate, Neogastrostyla aqua nov. gen., nov. spec. isolated from River Yamuna, Delhi, India, is described using morphological, morphometric and morphogenetic characters from live and stained cells supplemented with derivation of phylogenetic relationships using SSU rRNA gene. Neogastrostyla aqua nov. gen., nov. spec., is characterized by light yellow cortical granules present singly or in clusters of two to five, distributed randomly; parental adoral zone of membranelles retained unchanged for proter; Oxytricha-pattern of paroral and endoral; 25–27 frontal-ventral-transverse cirri including a distinct bipartite frontoventral row of composite origin; three dorsal kineties with no fragmentation of the third kinety, two dorsomarginal kineties, three caudal cirri, two macronuclear nodules and two or three micronuclei. Though Neogastrostyla aqua nov. gen., nov. spec. has a frontoventral row like Gastrostyla species, it differs distinctly in the combination of characters from Gastrostyla and other genera with Gastrostyla-like ventral ciliature (Protogastrostyla, Hemigastrostyla, Apogastrostyla and Pseudogastrostyla) particularly in the colour and distribution of cortical granules as well as arrangement and formation of ciliature. According to the phylogenetic analyses, Neogastrostyla aqua nov. gen., nov. spec. clustered consistently with Gastrostyla sp. Y2 (no description available), Oxytricha granulifera and Architricha indica as close neighbours.

The morphology, morphogenesis and molecular phylogeny of the oxytrichid ciliate, Monomicrocaryon euglenivorum euglenivorum (Kahl, 1932) Foissner, 2016, isolated from freshwater in a seaside park, Guangzhou, China, were investigated. Monomicrocaryon euglenivorum euglenivorum can be recognized as follows: caudal cirri in midline of body; dorsal kinety 1 without a one-kinetid-wide gap; transverse cirri acicular or rod-shaped with a fringed distal end; right marginal row commences at level of buccal vertex or anterior to buccal vertex. The main events during binary fission are as follows: (1) the proter retains the parental adoral zone of membranelles entirely; (2) frontoventral-transverse cirral anlagen I-VI are segmented in the ordinary pattern 1:3:3:3:4:4 from left to right, which form three frontal, four frontoventral, one buccal, three postoral ventral, two pretransverse ventral and five transverse cirri, respectively; (3) dorsal morphogenesis is in the typical Oxytricha-pattern, but fragmentation of dorsal kinety 3 is indistinct; and (4) three caudal cirri are formed, one at the posterior end of each of dorsal kineties 1, 2 and 4. Phylogenetic analyses based on SSU rDNA sequences showed that M. euglenivorum euglenivorum clustered with Kleinstyla dorsicirrata and Heterourosomoida lanceolata rather than with its congener M. elegans. The genus Monomicrocaryon is not monophyletic in this study; however, its monophyly is not rejected by the AU test.

The spatial variations of periphytic ciliate functional traits to environmental heterogeneity during an annual cycle were studied at functional trait resolution in a typical coastal area of the Yellow Sea. Samples were monthly collected using microscopic glass slides at four sampling sites within a gradient of pollution during 1-year cycle. The second-stage analysis was carried out to explore the interactions of annual variations in functional traits of the periphytic ciliates among four sampling sites. Results demonstrated that (1) the functional traits of the periphytic ciliates showed clear spatial variations in annual cycle along the gradient of pollution; and (2) the spatial variations of the ciliate functional pattern in annual cycle were significantly associated with the changes of environmental conditions, especially the COD and nutrients among four study sites, either alone or in association with DO and pH. The results suggested that the annual pattern of functional traits might reflect the environmental heterogeneity in marine ecosystems.

Black spot gill syndrome in the northern shrimp, Pandalus borealis, is caused by an apostome ciliate, Synophrya sp., found within the gill lamellae. Whole mount staining, thin section histology, electron microscopy, and molecular studies were carried out on infected gills. The Synophrya 18S rRNA from Pandalus borealis (Genbank accession no. KX906568) and from two portunid crab species, Achelous spinimanus (Genbank accession no. MH395150) and Achelous gibbesii (Genbank accession no. MH395151) was sequenced. Phylogenetic analyses confirmed the identity of these ciliates as apostomes. The 18S rRNA sequence recovered from P. borealis shared 95% nucleotide similarity with the sequences recovered from the portunid crab species suggesting that it is a different species of Synophrya. The invasive hypertrophont stages, with a distinctive macronuclear reticulum, ranged in size from 300 to 400 µm with as many as 5 large forms/mm2 of gill tissue. Histotrophic hypertrophont stages and hypertomont stages were observed in these studies. The presence of the parasite was linked to the formation of melanized nodules (up to 9 nodules/mm2 of gill tissue) by the host and in some cases to extensive necrosis. Other studies have reported Synophrya sp. infections in P. borealis from Greenland, Labrador and Newfoundland, but further studies are necessary to determine the prevalence of this parasite in the dense schools of northern shrimp in the North Atlantic. Questions remain as to the possibility of epizootics of this pathogen and its impact on northern shrimp populations.

The article is dedicated to the reproduction of behavior of a class of protozoans (ciliates) using computer simulation and genetic optimization. Protozoans have minimal cognitive abilities and no neural system. The only basis of their control system is mRNA and protein systems inside the cell. Ciliates have primitive sensitive receptors which can percept information only from the closest environment. But, nevertheless, unicellular organisms use their cognitive capacities for obstacles avoiding. In this paper, ethology of ciliate Uronychia transfuga is reproduced using a simple GasNet neural network and genetic optimization. It is showed that neural network of only 7 neurons combined with simple learning model is enough to achieve robust and natural behavior.

A new spathidiid ciliate, Apertospathula oktemae n. sp., was isolated from bottom sediments on the eastern shore of Lake Van, Turkey. The living cells are clavate and 45-80 x 17-30 mu m in size. This species is characterized by a lasso-shaped circumoral kinety composed of more than 100 dikinetids, 16 meridionally arranged somatic ciliary rows, a three-rowed dorsal brush with 1.5-2.0 mu m long bristles, an oblong and curved macronucleus with an ellipsoidal or globular micronucleus, numerous refractive granules in the anterior portion of the cell, and a single posterior contractile vacuole. This new species lives in alkaline brackish water. Apertospathula oktemae differs from congeners by their body shape, number of oral dikinetids, presence of refractive granules, and their habitat. This is the first study to investigate the 18S rRNA gene sequence of a member of the genus Apetrospathula. Phylogenetic trees show that Apertospathula oktemae is most closely related to Arcuospathidium sp. There is a discrepancy between the morphological classification system of the spathidiid ciliates and their molecular phylogeny. To overcome this problem, more molecular data, obtained from more taxa from various geographical regions of the world, are needed. (C) 2018 Published by Elsevier GmbH.

The living morphology, infraciliature and morphogenesis of a new urostylid ciliate, Caudiurostyla sinensis gen. nov., spec. nov., isolated from a soil habitat in China, was investigated. The new, monotypic genus is defined by having frontal cirri arranged in a bicorona, distinct transverse cirri, midventral pairs only, buccal cirrus, frontoterminal cirri, multiple marginal cirral rows that replicate independently via within row anlagen formation, more than three dorsal kineties, and caudal cirri. The main morphogenetic features of the new species are: (1) the posterior part of the parental adoral zone is renewed in situ; (2) the marginal cirral rows and dorsal kineties develop intrakinetally; (3) a caudal cirrus is formed at the posterior end of each dorsal kinety; and (4) macronuclear nodules fuse into a single mass during the middle stage. Based on the morphology and morphogenesis, the new genus differs from Pseudourostyla and Hemicycliostyla by presence of caudal cirri.

Microplastics are considered environmental pollutants of serious concern. In freshwater environments, they can affect aquatic biota and accumulate along the food web. Therefore, this study investigated the capacity of bacterivorous freshwater ciliates, essential members of the aquatic food chain, to ingest plain and fluorescently-labeled polystyrene microspheres. Two holotrich ciliates were isolated from a stream in KwaZulu-Natal (South Africa) and identified as members of the genera Paramecium and Tetrahymena based on morphological characteristics and 18S rRNA gene sequence analysis. While the larger bacterivorous ciliate Paramecium sp. strain RB1 ingested all three sizes of plain polystyrene microbeads tested (2,5,10 μm), the smaller sized Tetrahymena sp. strain RB2 only ingested microbeads of 2 and 5 μm. The two ciliates ingested polystyrene microbeads at rates ranging from 1650 to 3870 particles x ciliate−1 x hour−1 for all particle sizes ingested, matching rates determined for selected microbial prey (E. coli, S. cerevisiae) of similar size. The ability to ingest non-nutritious microplastic particles was confirmed for both ciliates using fluorescently-labeled microbeads as these were detected in food vacuoles by fluorescence microscopy. Therefore, ciliates such as Paramecium sp. strain RB1 and Tetrahymena sp. strain RB2 can contribute to the transfer and bioaccumulation of microplastics in freshwater food webs in South Africa.

The spatial and temporal planktonic ciliate community structure of a large shallow eutrophic lake was described in detail based on a monthly monitoring campaign over 2 years using the quantitative protargol stain approach. We found that there was a large variety and low constancy of ciliate plankton and a clear advantage of several small species. Balanion planctonicum, Rimostrombidium brachykinetum, and Urotricha farcta contributed 19.7%, 13.4%, and 10.7% to the total abundance, respectively. The ciliate community was significantly varied in different lake regions of different eutrophication levels, and the distribution of some of the main species, especially prostomatids and scuticociliatids, might be closely related to the nutrient level of the lake regions. The seasonal dynamics of ciliate taxa with similar functional feeding habits across regions at different trophic levels are more convergent than those of species with very different functions, and the top-down effect (cladocerans, rotifers), nutrition, and water temperature were the key factors shaping ciliate community structure. The results of this study accentuate the important effects of species functional diversity on community differences and may improve our knowledge of ciliate diversity and functional ecology in shallow eutrophic lakes.

During an investigation of parasitic ciliates in northern China, two Trichodina species, T. acuta Lom, 1970 and T. nigra Lom, 1960, were isolated from the freshwater fish Cyprinus carpio Linnaeus, 1758. The morphology of each species was investigated based on dry silver nitrate-stained specimens. In addition, the molecular phylogeny of each was analyzed based on small subunit ribosomal DNA (SSU rDNA) sequence data. Trichodina acuta can be distinguished from its congeners by the undefined periphery of the central circle, the distinct gap between the rays and the central circle, and the distinctly sickle-shaped blades. Trichodina nigra is a cosmopolitan ciliate and is characterized by its densely linked denticles, broad, rounded spatula-shaped blades, robust central parts, and well developed rays. Phylogenetic analyses revealed that T. acuta and T. nigra nest within different clades, supporting the assertion that the GC content of SSU rDNA sequences could reflect evolutionary relationships among Trichodina species.

Cryptocaryon irritans is a pathogenic ectoparasitic ciliate that infects marine teleosts, causing massive mortality and economic losses in aquaculture. Ultraviolet light (UV) and ozone (O3) are commonly used for disinfection in factory aquaculture; however, the efficacy of neither method against C. irritans had been evaluated. This study aimed to evaluate the efficacy of UV and ozone in destroying C. irritans. UV or ozone treatment changed or ruptured the shape of C. irritans theronts, although C. irritans tomonts showed some resistance. The minimum in vitro lethal doses of UV and ozone against theronts were 2.88× 105 μWs/cm2 and 0.15 mg/L, respectively. In vivo, UV and ozone-treated theronts lost their ability to infect pompano (Trachinotus ovatus) when exposed to doses above 1.84 × 105 μWs/cm2 and 0.10 mg/L, respectively. Unexpectedly, exposure to low ozone levels (

Tetrahymena pyriformis is a histophagus protozoan ciliate responsible for tetrahymenosis in various aquatic organisms including the tiger barb Puntius tetrazona. The morphology, infraciliature, SSU rRNA and cox 1 gene sequences of T. pyriformis isolated from P. tetrazona from a fish market in Harbin was investigated using living observation and silver staining methods. In addition, an SSU-rDNA-targeted oligonucleotide probe labelled with a fluorochrome was designed for rapid identification of T. pyriformis. Diseased fish secreted copious amounts of mucus on the skin and had dark-red spots in the eyes and at the base of tail fins. Gills of all diseased fish were shriveled and pale. T. pyriformis could be directly found when examined histologically by hematoxylin-eosin staining. The results showed that some T. pyriformis cells were present on the surface of the gill filaments. There was also abnormal bunting of the abdomen, and the gill filaments and muscle tissue were deformed, shrunken, and cracked. Successful infection of P. tetrazona was achieved with T. pyriformis by scratch inoculation with a range of infectious doses. The results indicate that T. pyriformis invades P. tetrazona through lesions on the body surface, and a large infectious dose could accelerate the death of the infected fish.

The cell mouth is a property of the vast majority of free-living and endosymbiotic/epibiotic ciliates of the class Oligohymenophorea. Cytostome, however, naturally absents in the whole endosymbiotic subclass Astomatia and was naturally or experimentally lost in a few members of the subclass Hymenostomatia. This poses a question of how homoplastic might be the lack of oral structures in the oligohymenophorean evolution. To address this question, we used two mitochondrial genes, five nuclear markers, and detailed morphological data from an enigmatic mouthless ciliate, Clausilocola apostropha, which we re-discovered after more than half of a century. According to the present phylogenetic analyses, astomy evolved at least three times independently and in different time frames of the oligohymenophorean phylogeny, ranging from the Paleozoic to the Cenozoic period. Mouthless endosymbionts inhabiting mollusks (represented by Clausilocola), planarians (Haptophrya), and annelids ('core' astomes) never clustered together. Haptophrya grouped with the scuticociliate genus Conchophthirus, 'core' astomes were placed in a sister position to the scuticociliate orders Philasterida and Pleuronematida, and Clausilocola was robustly nested within the hymenostome family Tetrahymenidae. The tetrahymenid origin of Clausilocola is further corroborated by the existence of mouthless Tetrahymena mutants and the huge phenotypic plasticity in the cytostome size in tetrahymenids.

The genus Alexandrium often forms harmful algal blooms causing human illness and large-scale mortality of fish and shellfish. Thus, Alexandrium bloom dynamics are primary concerns for scientists, government officials, aquaculture farmers, and the public. To understand bloom dynamics, mortality due to predation needs to be assessed; however, interactions between many Alexandrium species and their potential predators have not previously been reported. Thus, feeding by five common heterotrophic dinoflagellates (Oxyrrhis marina, Gyrodinium dominans, Polykrikos kofoidii, Pfiesteria piscicida, and Oblea rotunda) and a naked ciliate (Strombidinopsis sp.) on 12 Alexandrium species was examined. Furthermore, the growth and ingestion rates of P. kofoidii on A. minutum CCMP 1888 (previously A. lusitanicum), A. minutum CCMP 113, and A. tamarense were measured as a function of prey concentration. The growth rates of P. kofoidii on the other Alexandrium species at single high prey concentrations were measured, at which the growth rates on A. minutum CCMP 1888 and A. tamarense were saturated. Feeding occurrence by these predators on 12 Alexandrium species could be categorized into 6 different prey groups. Each Alexandrium species was consumed by at least one predator; however, there was no Alexandrium species that was eaten by all six predators. Cells of A. minutum CCMP 1888, A. minutum CCMP 113, and A. tamarense were fed upon by four predators, but A. affine and A. pacificum by only one predator species, P. kofoidii or Strombidinopsis sp. Furthermore, A. minutum CCMP 1888 and A. tamarense supported high growth rates of P. kofoidii, but the other Alexandrium species did not support, but rather inhibited P. kofoidii growth. With increasing prey concentrations, the growth and ingestion rates of P. kofoidii on A. minutum CCMP 1888 and A. tamarense increased and became saturated, whereas those on A. minutum CCMP 113 continuously decreased. The maximum growth rates of P. kofoidii on A. tamarense and A. minutum CCMP 1888 were 1.010 and 0.765 d−1, respectively, and P. kofoidii maximum ingestion rates were 26.2 and 11.1 ng C predator−1d−1, respectively. In contrast, the growth rates of P. kofoidii on the other Alexandrium species at single high prey concentrations were almost zero (A. pacificum) or negative. Based on the feeding occurrence and growth and ingestion rates of predators on 12 Alexandrium species, it is suggested that common heterotrophic protistan predators respond differently to different Alexandrium species, and thus ecological niches of the Alexandrium species may be different from each other. These results may provide an insight into the roles of protistan predators in bloom dynamics of Alexandrium species.

The odontostomatids are among the least studied ciliates, possibly due to their small sizes, restriction to anaerobic environments and difficulty in culturing. Consequently, their phylogenetic affinities to other ciliate taxa are still poorly understood. In the present study, we analyzed newly obtained ribosomal gene sequences of the odontostomatids Discomorphella pedroeneasi and Saprodinium dentatum, together with sequences from the literature, including Epalxella antiquorum and a large assemblage of ciliate sequences representing the major recognized classes. The results show that D. pedroeneasi and S. dentatum form a deep-diverging branch related to metopid and clevelandellid armophoreans, corroborating the old literature. However E. antiquorum clustered with the morphologically discrepant plagiopylids, indicating that either the complex odontostomatid body architecture evolved convergently, or the positioning of E. antiquorum as a plagiopylid is artifactual. A new ciliate class, Odontostomatea n. cl., is proposed based on molecular analyses and comparative morphology of odontostomatids with related taxa.

Summary Complex behavior is associated with animals with nervous systems, but decision-making and learning also occur in non-neural organisms [ 1 ], including singly nucleated cells [ 2 , 3 , 4 , 5 ] and multi-nucleate synctia [ 6 , 7 , 8 ]. Ciliates are single-cell eukaryotes, widely dispersed in aquatic habitats [ 9 ], with an extensive behavioral repertoire [ 10 , 11 , 12 , 13 ]. In 1906, Herbert Spencer Jennings [ 14 , 15 ] described in the sessile ciliate Stentor roeseli a hierarchy of responses to repeated stimulation, which are among the most complex behaviors reported for a singly nucleated cell [ 16 , 17 ]. These results attracted widespread interest [ 18 , 19 ] and exert continuing fascination [ 7 , 20 , 21 , 22 ] but were discredited during the behaviorist orthodoxy by claims of non-reproducibility [ 23 ]. These claims were based on experiments with the motile ciliate Stentor coeruleus. We acquired and maintained the correct organism in laboratory culture and used micromanipulation and video microscopy to confirm Jennings’ observations. Despite significant individual variation, not addressed by Jennings, S. roeseli exhibits avoidance behaviors in a characteristic hierarchy of bending, ciliary alteration, contractions, and detachment, which is distinct from habituation or conditioning. Remarkably, the choice of contraction versus detachment is consistent with a fair coin toss. Such behavioral complexity may have had an evolutionary advantage in protist ecosystems, and the ciliate cortex may have provided mechanisms for implementing such behavior prior to the emergence of multicellularity. Our work resurrects Jennings’ pioneering insights and adds to the list of exceptional features, including regeneration [ 24 ], genome rearrangement [ 25 ], codon reassignment [ 26 ], and cortical inheritance [ 27 ], for which the ciliate clade is renowned.

In recent years, black-spot shell disease has appeared on the shells of Akoya pearl oysters, Pinctada fucata, causing serious problems in cultured pearl production. This disease was believed to be caused by boring of Polydora ciliata into calcareous substrate, and a control measure against P. ciliata was developed. As a result, boring activity of P. ciliate decreased, but black-spot shell disease remains a serious problem. We detected the genus Tenacibaculum specifically from the shells of diseased oysters using PCR-DGGE, and isolated Tenacibaculum sp. strain Pbs-1 from the diseased oyster shells. Analyses of 16S rRNA gene sequence homology and its biochemical and morphological characteristics suggested that strain Pbs-1 was a new species of Tenacibaculum. We conducted four infectivity experiments by different infection methods: smear, injection, immersion, or a combination of wound and immersion. The highest infectivity (100%) in the shell was observed in the test group by the smear method, which was accompanied by severe clinical signs that included a focal blackish discoloration of the shell. The results of the infectivity experiments indicated that the newly isolated Tenacibaculum sp. strain Pbs-1 is one of the putative causative agents of black-spot shell disease in Akoya pearl oysters.

The diversity of marine benthic ciliates is largely known from the intertidal zone. No comparative data are available for the change of ciliate communities from the intertidal to offshore sediments in the Yellow Sea. We investigated the community composition and diversity of benthic ciliates at two intertidal (sandy and silty-sand) stations and eight offshore stations along a latitudinal transect in the Yellow Sea. The ciliate abundance and biomass decreased almost linearly with increasing water depth and distance from the intertidal zone. Diversity indices showed a similar trend. By contrast, the total species richness and taxonomic diversity were much higher in the offshore sediments than in the intertidal area. Among the total of 94 species identified, only 20 species were shared by the two habitats, which were characterized by different dominant ciliate assemblages. Carnivorous ciliates always constituted the primary feeding type in terms of biomass at all offshore stations and the intertidal sandy station, whereas at the intertidal silty-sand station the primary feeding group varied throughout the period of sampling. Multivariate analyses indicates the ciliate communities were significantly different between the two habitats. Bottom water temperature and sediment grain size were the key factors that explained the ciliate community structure.

Predator-prey interactions of planktonic protists are fundamental to plankton dynamics and include prey selection, detection, and capture as well as predator detection and avoidance. Propulsive, morphology-specific behaviors modulate these interactions and therefore bloom dynamics. Here, interactions between the mixotrophic, harmful algal bloom (HAB) dinoflagellate Dinophysis acuminata and its ciliate prey Mesodinium rubrum were investigated through quantitative microvideography using a high-speed microscale imaging system (HSMIS). The dinoflagellate D. acuminata is shown to detect its M. rubrum prey via chemoreception while M. rubrum is alerted to D. acuminata via mechanoreception at much shorter distances (89 ± 39 μm versus 41 ± 32 μm). On detection, D. acuminata approaches M. rubrum with reduced speed. The ciliate M. rubrum responds through escape jumps that are long enough to detach its chemical trail from its surface, thereby disorienting the predator. To prevail, D. acuminata uses capture filaments and/or releases mucus to slow and eventually immobilize M. rubrum cells for easier capture. Mechanistically, results support the notion that the desmokont flagellar arrangement of D. acuminata lends itself to phagotrophy. In particular, the longitudinal flagellum plays a dominant role in generating thrust for the cell to swim forward, while at other times, it beats to supply a tethering or anchoring force to aid the generation of a posteriorly-directed, cone-shaped scanning current by the transverse flagellum. The latter is strategically positioned to generate flow for enhanced chemoreception and hydrodynamic camouflage, such that D. acuminata can detect and stealthily approach resting M. rubrum cells in the water column.

In this study, we tested the hypothesis that the functional diversity of benthic ciliates has high potential to monitor marine ecological status. Therefore, we investigated the spatial and temporal variation of functional diversity of benthic ciliates in the Yangtze Estuary during one year using biological traits analyses and functional diversity indices. Traits and community compositions showed clear spatial and temporal variations. Among a variety of biological traits, feeding type and body size emerged as strongest predictable variables. Functional divergence (FDiv) had an advantage over two other functional diversity indices, as well as over classical diversity measures (i.e. richness, evenness, Shannon-Wiener) to infer environmental status. Significant correlations between biological traits, FDiv and environmental variables (i.e. nutrients, temperature, salinity) suggested that functional diversity of benthic ciliates might be used as a bio-indicator in environmental status assessments. Further mandatory researches need to implement functional diversity of ciliates in routine monitoring programs were discussed.

Cryptocaryon irritans is a type of marine ectoparasitic ciliate that infects teleost fishes. To illustrate the susceptibility and innate immune mechanism of fishes to C. irritans, four species of marine perciform fishes were selected in Fujian Province, a high-prevalence area of cryptocaryoniasis in China. The survival, diameter/number of tomonts, and infection ratio among Larimichthys crocea, Lateolabrax japonicus, Pagrus major, and Nibea albiflora were compared after artificial infection. Meanwhile, the immobilization titers of four fish species with no C. irritans infection were detected. Results showed that survival and serum immobilization titer of N. albiflora were significantly higher than those of the other three fish species. A strong negative linear correlation was found between the survival/serum immobilization titer and the mean tomont diameter. In addition, the smallest C. irritans infection ratio was found in N. albiflora, implying that the serum of fishes especially that of N. albiflora, inhibited the development of parasitic C. irritans cells, and the smallest tomont size was directly related to the number of infective theronts corresponding to the highest survival of fish. Moreover, complement activity inhibition assays suggested that the alternative complement pathway might play a major role in C. irritans resistance.

Consortia of the peritrich ciliate Vorticella oceanica and the planktonic diatom Chaetoceros coarctactus are reported from the South Atlantic Ocean. The morphologies of the constituent species were similar to their counterparts from other geographical regions, revealing a widespread distribution in tropical waters. Besides, we describe Pseudovorticella coscinodisci sp. nov. that lives on Coscinodiscus wailesii and other pelagic diatoms off Brazil. The zooids were 34-45μm long, and 19-30μm wide with a stalk too short to coil. The cell surface showed a reticulate pellicle with 18-19 and 11-12 rows above and below the aboral ciliary wreath, respectively. In the SSU rDNA phylogeny V. oceanica clustered between the clades of Vorticella and Pseudovorticella/Epicarchesium, and Pseudovorticella coscinodisci sp. nov. clustered as a sister group of Pseudovorticella paracratera and P. sinensis. The V. oceanica-C. coarctactus consortium likely represents an obligate species-specific mutualistic symbiosis as the constituents are not known as free-living forms. In contrast, the diatom hosts are known as free-living forms in the consortia of Pseudovorticella coscinodisci. The new molecular data and species description will be valuable dataset for future research on the diversity and ecological significance of ciliate-diatom epibiotic consortia.

In a study to investigate ciliate diversity, we discovered a new soil ciliate. Holostichides terrae nov. spec. was examined and identified based on observations of living cells and stained specimens. In addition, the nuclear SSU rRNA gene along with morphology was analyzed to infer its phylogenetic position. The new species closely resembles H. dumonti, but can be distinguished by the morphology of the pharynx (with rod-shaped structure vs. lacking) and the number of frontoterminal cirri (invariably two vs. usually more than two). Molecular analyses indicate that the genus Holostichides is not monophyletic, and H. terrae is closely related with the genera Birojimia and Hemicycliostyla, both of which have a pharynx with rod-shaped structures, as also seen in H. terrae.

Cryptocaryon irritans, an important protozoan ciliate, infects almost all species of marine teleosts and causes heavy economic losses in aquaculture. In industrial aquaculture, culture container rotation is an effective method to control cryptocaryoniasis. However, the accurate frequency and times of container rotation for different temperatures or fish species has not been reported but is very important information for the application of the method. In the present study, we investigated the duration of C. irritans trophont residence and theront production in three fish species at temperatures from 18 °C to 32 °C with 2 °C intervals. The results indicate that duration of trophont residence and theront excystment was shorter with rises in temperature, especially from 18 °C to 22 °C. In different fish species, the length of trophont residence varied whereas the length of theront excystment was very similar at the same temperature. In line with these data, we determined the frequency and times that tomonts were removed, and results demonstrated that all the tomonts can be completely removed with 2 or 3 days interval for 2 or 3 times (from 22 °C to 32 °C), and the removal of tomonts was identical in three fish species at the same temperature. At 18 °C and 20 °C, however, the interval of tomont removal was > 4 days. Lastly, we verified the removal of tomonts with Trachinotus ovatus as host at 22 °C and 30 °C by a placemat removal method. In conclusion, these data provide an important basis for defense against C. irritans infection by the interruption of its life cycle in an intensive aquaculture system.

Newly isolated strains of the ciliate Paramecium calkinsi and their cytoplasmic bacterial endosymbionts were characterized by a multidisciplinary approach, including live observation, ultrastructural investigation, and molecular analysis. Despite morphological resemblance, the characterized P. calkinsi strains showed a significant molecular divergence compared to conspecifics, possibly hinting for a cryptic speciation. The endosymbionts were clearly found to be affiliated to the species “Candidatus Trichorickettsia mobilis” (Rickettsiales, Rickettsiaceae), currently encompassing only bacteria retrieved in an obligate intracellular association with other ciliates. However, a relatively high degree of intraspecific divergence was observed as well, thus it was possible to split “Candidatus Trichorickettsia” into three subspecies, one of which represented so far only by the newly characterized endosymbionts of P. calkinsi. Other features distinguished the members of each different subspecies. In particular, the endosymbionts of P. calkinsi resided in the cytoplasm and possessed numerous peritrichous flagella, although no motility was evidenced, whereas their conspecifics in other hosts were either cytoplasmic and devoid of flagella, or macronuclear, displaying flagellar-driven motility. Moreover, contrarily to previously analyzed “Candidatus Trichorickettsia” hosts, infected P. calkinsi cells frequently became amicronucleate and demonstrated abnormal cell division, eventually leading to decline of the laboratory culture.

Macrostylis marionae n. sp. is described by means of integrative taxonomy. It is the second isopod species (Crustacea) described from the hadal Puerto Rico Trench. It differs from other Macrostylidae (Janiroidea) predominantly by the lack of the tergal borders between the fossosome segments. Adult males of M. marionae n. sp. differed from females and juveniles of both sexes in a higher number of peritrich ciliate epibionts. In total, 64.3% of adult males and only 10.5% of adult females were infested. Because macrostylids are generally considered infaunal, with a digging lifestyle, while peritrichs require aquatic medium for filter feeding, this observed pattern led to the hypothesis of a behavioural sexual dimorphism in this species of Macrostylidae. Accordingly, the epibionts may prefer adult male macrostylids as basibionts because of a rather epifaunal and roaming lifestyle. In contrast they may avoid females due to a stationary and infaunal behaviour. Additionally, the stage progression of the M. marionae male ontogeny was reconstructed.

The effect of controlled sub-surface CO2 emissions on edaphic ciliate communities was examined in experimental mesocosms and then compared with the effect of natural CO2 emissions from natural vents on edaphic ciliate communities to analyse the potential of ciliates as bioindicators of soil CO2 increments. The relative abundance of each taxonomic family formed the basis for developing the metrics of the ciliate assemblages in order to obtain a quantitative soil quality bioassessment, the edaphic ciliate bioindex. Twenty-four mesocosms filled with soil and equipped with controlled CO2 injection were built for the experiment. To evaluate the potential of soil ciliates as bioindicators, the same CO2 fluxes were analyzed in both study conditions, from 0 to more than 150 ml CO2 d−1. Several diversity indices and other group ratios and percentages of community structure were calculated. Biodiversity of ciliates (Equitability, Margalef and Shannon indices) decreased with the increase in CO2 fluxes, and Colpodid/Polyhymenophorean ratio increased. This indicated adverse conditions for the ciliates in the soil. There was a positive significant relationship between the observed CO2 values measured in the test set and the values expected according to their inhabiting ciliate community. The weighted averaging of taxonomic group indicator method supported the experimental results attesting to the potential of edaphic ciliates as bioindicators of CO2 flux increments. The ecological profiles estimated within the training test, based on the taxonomic level of family, were reliable and provided a basis for the use of ciliates to monitor soil CO2 flux increments in a wide range of ecological conditions.

We incubated tomonts of Cryptocaryon irritans in a hypoxic seawater environment (1.4–1.7 mg/L O2) (low dissolved oxygen; DO) and examined their development using a acetocarmine whole-mount staining method we developed for nuclear staining. They showed little development and stayed in the dormant phase in the hypoxic environment. When transferred into the hypoxic environment after incubation in an oxic environment (air-saturated, 8.7–8.9 mg/L O2) for 1–4 days, their development stopped in 1 day. However, when dormant tomonts generated in the hypoxic environment were transferred to the oxic environment, they resumed development and released theronts. These results indicate that tomonts can become dormant when exposed to a hypoxic environment, but can resume development when exposed to an oxic environment at any developmental stage. When exposed to the oxic environment, tomonts recovered from 1-month dormancy and released as many theronts as control tomonts constantly incubated in the oxic environment. The infectivity of theronts from the recovered tomonts was similar to the control tomonts. Thermoclines prevent oxygen-rich surface seawater from reaching the bottom of water column and create a hypoxic sea floor environment in summer; these thermoclines are broken down in autumn or after typhoons. The long-term viability of dormant tomonts in hypoxic environments may be a key factor in the autumn outbreaks of cryptocaryoniasis in floating net cages in temperate waters.

The backbone of benthic marine monitoring programs is the biological component, traditionally the macrofauna inventory. Such macrofauna-based environmental impact assessments (EIA), however, are very time consuming and expensive. To overcome these shortcomings, we used environmental metabarcoding to test the potential of protists as bioindicators in EIAs. Therefore, we analyzed taxonomic metabarcodes (V9 region of the SSU rRNA), obtained from sediment samples collected along a 400-m transect extending from below salmon cages towards the open sea along the predominant current flow. The obtained genetic data of protistan communities were compared to benchmark data obtained from traditional macrofauna surveys of the same samples. Ciliates emerged as the most powerful indicators mirroring the macrofauna benchmark patterns with statistical significance. Ordination analyses showed that ciliate communities resolved impacted sampling sites below and in immediate vicinity of the salmon cages even better than macrofauna communities. It can be concluded that ciliates allow for a better fine-scale resolution of impact conditions than traditional monitoring methods. Other protistan taxon groups such as diatoms and chrysophytes were not as successful as marine benthic indicators compared to ciliates. We conclude that the implementation of ciliate metabarcoding can substantially improve EIAs. We discuss further mandatory research needs to make ciliate metabarcoding a routine tool in official regulations for EIAs in salmon farming.

Mesanophrys sp. is a newly discovered parasitic ciliate, which can cause the death of swimming crabs (Portunus trituberculatus) during the winter period. In this study, the anti-parasitic effects and toxicity of quinine sulfate on Mesanophrys sp. were investigated. In vitro results showed that Mesanophrys sp. mortality rates were 100% when treated with quinine sulfate at 21.0, 18.0, 12.0, 12.0, 12.0, 12.0, and 12.0 mg/L for 0.5, 1, 2, 4, 6, 12, and 24 h, respectively. The 0.5 h-LC50, 1 h-LC50, 2 h-LC50, and 24 h-LC50 of quinine sulfate against Mesanophrys sp. were 11.87, 10.38, 8.71, and 5.23 mg/L, respectively. With the increased concentration of quinine sulfate or the prolongation of the treatment time, the morphology and structure of Mesanophrys sp. changed significantly. The parasites became rounded, cilia were shed, nuclear chromatin agglomerated but then disappeared, the mitochondrial membrane deformed and the ridge structure partially collapsed, cell membranes ruptured and the cytoplasm leaked out. In an in vivo trial, by adding quinine sulfate (12 mg/L) to the culture water, the survival rate of artificially infected crabs was 86.67 ± 5.77%, which was not significantly different from the survival rate (90%) of the crab in the control group but was significantly higher than the infection group without drug exposure (3.33 ± 5.77%). The protection rate of the drug against disease was 83.34%. In the treatment test, a dose of quinine sulfate (12 mg/kg) was given three times as an injection into a swimming leg of a crab that had been experimentally infected. Injection resulted in an increase in the survival of infected crabs from 11.11 ± 9.62% (infection group without treatment) to 77.78 ± 9.62%. There was no statistical difference in survival between the latter group and the control group (94.44 ± 9.62%). Finally, the bathing and injection methods caused no apparent harm to the feeding and movement activities of P. trituberculatus.

The commercially important marine microalgae Nannochloropsis oceanica is easily ingested by protozoan predators during large-scale cultivation. However, investigations into the effect of microalgae on the growth of protozoa are scant. A feeding experiment was conducted with Euplotes vannus grazing on different concentrations of N. oceanica. The ciliate population was significantly lower in the high concentration of algae than that in the low or medium algal concentration treatments. The density of ciliates cultured in algae filtrate media was significantly lower than that in lysate media and the blank control. Furthermore, the algal cell filtrate was added to three other protozoan populations, and they all gradually lost their ability to move and their body shape changed. This study investigated the interactions between N. oceanica and protozoan predators and provides insight on using microalgal extracellular substances to control biological contamination in the future.

The morphology and molecular phylogeny of a new metopid ciliate, Urostomides spinosus nov. spec., discovered in a freshwater ditch in Qingdao, China, were investigated using live observation, morphometry and protargol staining as well as molecular phylogenetic methods. Diagnostic features of the new species include a broadly obpyriform body carrying three posterior spines, eight somatic kineties, five preoral dome kineties with specialized row 3, adoral zone composed of about 28 membranelles, making a 270° turn around body axis. Phylogenetic analyses of the SSU rDNA sequence revealed that the genus Urostomides is monophyletic, but its interspecific relationships remained unresolved. Moreover, a closer relationship of the new species with the morphologically similar Urostomides campanula was not supported by the molecular data.

Investigation of the ciliate communities from the digestive tract of different wild vertebrates is important in context of host-specificity of different ciliate species and the detection of any cases of non-specific infection. Here we present a description and analysis of the fauna of ciliates (Litostomatea, Trichostomatia) inhabiting the intestine of the wild plains zebra (Equus quagga Boddaert, 1785) in South Africa. Nineteen species belonging to 12 genera of five families were found. Five species were specific to Equus quagga; one was also found in Equus zebra; 29 are common to different equids; and one had been previously described from rhinoceros. For the first time, we used immunofluorescent staining to investigate microtubule cytoskeletons in trichostomatids. We found that this staining method is useful for the identification of trichostomatids.

Contaminations in microalgae cultures are one of the major drawbacks when cultivating in an industrial scale. What is often experienced as culture crash has been rarely investigated in detail. Here, we show that the ciliated protozoa Colpoda steinii is capable to clear a dense culture of the cyanobacterium Synechocystis sp. within 2–3 days. In a 200 L tubular photobioreactor, this ciliate frequently appeared and led to great losses. The ciliate was isolated and characterized in the laboratory. Its grazing rate exceeded the growth rate of three tested Synechocystis strains (Synechocystis PCC6803, Synechocystis CCALA192 and Synechocystis minuscula SAG 258.80) by far. Due to its devastating effect on Synechocystis sp., its ability to form cysts and its resilience, Colpoda steinii was experienced as serious threat for large scale cultures of Synechocystis sp. The most common means against contaminations are high salinities and high pH values. Though, cultivating with salinities up to 20‰ and pH values up to 10 did not inhibit Colpoda steinii. Other strategies like high ammonia concentration, carbon dioxide (CO2) asphyxiation and anoxic conditions during the dark period were tested against the ciliate as well. While high ammonia concentration and CO2 asphyxiation did no inhibit Colpoda steinii, partially anoxic conditions inhibited this ciliate effectively and appears to be a promising cultivation method for Synechocystis sp. under non-sterile conditions.

Oxytetracycline (OTC) is commonly employed in fish farms to prevent bacterial infections in China, and because of their widely and intensive use, the potential harmful effects on organisms in aquatic environment are of great concern. Ciliates play an important role in aquatic food webs as secondary producers, and Pseudocohnilembus persalinus, is one kind of them which are easily found in fish farms, surviving in polluted water. Therefore, using P. persalinus as experimental models, this study investigated the effects of oxytetracycline (OTC) on the growth, antioxidant system and morphological damage in pollution-resistant ciliates species. Our results showed that the 96-h EC50 values for OTC of P. persalinus was 21.38mgL-1. The increased level of SOD and GSH during 96h OTC stress was related to an adaptive response under oxidative stress induced in ciliates. Additionally, sod1, sod2 and sod3 exhibited a significant increased expression level compared to control group at 24h treatment, indicating a promoting of dense system in ciliates at this exposure time. However, only sod1 and sod2 showed raised expression level at 48h stress, showing the different sensitive of gene isoforms to some extent. With OTC treatment, damage of regular wrinkles, shrunk, twisted on the cell surface, even forming cyst of scuticociliatid ciliate cells were firstly observed by SEM (scanning electron microscope) in this study. Overall, physiological, molecular and morphological information on the toxicological studies of ciliates and more information on possibility of ciliates as indicators of contamination were provided in this study.

The mouflon’s traditional classification as a grazer has recently been questioned, therefore new insight into the species’ feeding and digestion is needed. The presence and share of different ciliate genera in the rumen may contribute to an understanding of a species’ feeding physiology, therefore we analysed the composition of mouflon rumen ciliates and correlated their density with the percentage of different food types eaten by the animals. We found that the dominant ciliates were Entodinium spp., with a small proportion of Anoplodinium denticulatum, Eudiplodinium maggii, Epidinium ecaudatum caudatum and Dasytricha ruminantium . The main food types taken by the animals were deciduous tree leaves, grass and bramble. The density of ciliates from the Entodinium genus rose with an increase in deciduous leaves in the diet and fell with an increase of graminoids in the diet. The density of ciliates from the Anoplodinium and Eudiplodinium sub-genera increased with a rise in tree shoots and was reduced with a rise of deciduous leaves in the diet. These results confirm that the protozoal fauna vary with current food composition in intermediate feeders.

ATP-binding cassette (ABC) transporters participate in transporting various substances, including xenobiotics, in or out of cells. However, their genetic information and function in ciliates remain still unclear. In this study, we sequenced and characterized two ABC transporter genes (EcABCB and EcABCC), and investigated the effect of cadmium (Cd) and benzo[a]pyrene (B[a]P) on their function and gene expression, using efflux assay and real-time reverse transcription-polymerase chain reaction (qRT-PCR), respectively, in the marine ciliate, Euplotes crassus. Sequencing analysis and efflux assay showed that EcABCB and EcABCC are typical ABC transporters, possessing conserved function. Exposure to Cd (≥5mg/L) and B[a]P (≥50.5μg/L) enhanced accumulation of a substrate. A significant increase in the expression of EcABCB and EcABC mRNA was observed at lower concentration in response to Cd and B[a]P. Our findings indicate that Cd and B[a]P could inhibit the efflux function of ABC transporters, leading to cellular toxicity in the ciliate.

Morphogenesis in a population of Urosoma salmastra collected from saline soil in Weinan, China, was investigated using protargol staining. The main morphogenetic event that characterizes U. salmastra is the inclusion of cirrus III/2 in the formation of the frontoventra-transverse cirral anlagen. We also provide small subunit ribosomal DNA gene sequences for a population of U. salmastra and for two populations of U. emarginata. The molecular phylogeny indicates that Urosoma is not monophyletic, viz, U. emarginata branches separately from its congeners and the closest relative of U. salmastra is Oxytricha granulifera.

A hypotrichous ciliate, Paragonostomoides xianicum n. sp., was discovered in soil on the surface of the Xi'an Circumvallation, Xi'an, China. Its morphology and some major ontogenetic stages were studied and the phylogenetic position was estimated using standard methods Paragonostomoides xianicum n. sp. is characterized as follows: body size about 75-90×15-25μm in vivo, elliptical and flexible; colourless mitochondrion-like cortical granules scattered throughout cell surface, about 0.8×0.6μm in size; contractile vacuole positioned at mid-body; frontoventral row IV extends beyond buccal vertex and frontoventral row VI extends to about body end; frontoventral cirri not in pairs; transverse cirri absent; three caudal cirri; two macronuclear nodules and one to four micronuclei. The ontogenetic process in P. xianicum n. sp. is basically similar to that in Metagonostomum gonostomoidum and Gonostomum-species and featured by: frontoventral-transverse cirri develop in five-anlage pattern, the rearmost cirri generated in the two rightmost FV anlagen are not set off posteriorly (like an ordinary TC), as well as FVT-anlagen n and n-1 form in secondary mode in P. xianicum. Phylogenetic analyses based on small subunit ribosomal DNA sequence data reveal a close relationship of P. xianicum n. sp. with Cotterillia bromelicola and two Gonostomum-species.