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The protistan genus Epistylis contains freshwater colonial species that attach to aquatic organisms in an epibiotic or parasitic relationship. They are known to attach to the epidermis and shells of aquatic turtles, but have not been reported to cause heavy infestations or morbidity in turtles. We documented heavy infestations of Epistylis spp. in several populations of Sonoran mud turtles (Kinosternon sonoriense) inhabiting livestock ponds in Arizona, USA, and rough-footed mud turtles (Kinosternon hirtipes) from livestock ponds in Texas, USA, over the course of several years. Severe Epistylis spp. infestations on mud turtles appeared to alter diving and swimming behavior when compared to uninfested conspecifics. Infestations were cleared in captivity using tap water or a 10% salt solution, and the turtles had no permanent damage to their shell or epidermis upon clearing. While several of the mud turtles we observed had poor body condition, it is possible that the severe infestations we observed were caused by a comorbidity associated with a pathogen, parasite, or poor habitat quality that made the turtles more susceptible to the Epistylis spp. infestation. Further research on causes for these severe infestations are warranted because they contribute to changes in behavior of the heavily infested turtles and may contribute to morbidity in Kinosternon spp. when mud turtles inhabit extremely warm, shallow, eutrophic aquatic habitats, such as livestock ponds. [ABSTRACT FROM AUTHOR]

Protozoa play a pivotal role in the microbial cycle, and ciliated protozoan grazing habits are associated with dimethyl sulfide (DMS) cycle. Many studies have explored the impacts of nanoplastics (NPs) and microplastics (MPs) on ecotoxicological effects of ciliates. However, limited research exists on NPs and MPs influences on the production of organic sulfur compounds. The impact of NPs and MPs on the production of dimethyl sulfoxide (DMSO) and carbonyl sulfide (COS) remains unclear. Therefore, we examined the impacts of three concentrations (1 × 105, 5 × 105, and 1 × 106 items/mL) of polystyrene (PS) NPs (50 nm) and MPs (1 and 5 μm) on the ecotoxicology and DMS/dimethylsulfoniopropionate (DMSP)/DMSO/COS production in the ciliate Uronema marinum. NPs and MPs exposure were found to reduce the abundance, growth rate, volume, and biomass of U. marinum. Additionally, NPs and MPs increased the superoxide anion radical (O 2 ˙─) production rates and malondialdehyde (MDA) contents (24 h), leading to a decline in glutathione (GSH) content and an ascend in superoxide dismutase (SOD) activity to mitigate the effects of reactive oxygen species (ROS). Exposure to PS NPs and MPs decreased the ingestion rates of algae by 7.5–14.4%, resulting in decreases in DMS production by 56.8–85.4%, with no significant impact on DMSO production. The results suggest a distinct pathway for the production of DMSO or COS compared to DMS. These findings help us to understand the NPs and MPs impacts on the marine ecosystem and organic sulfur compound yield, potentially influencing the global climate. [Display omitted] • Nano- and micro-plastics inhibited ciliate abundance and dimethyl sulfide yield. • O 2 ˙─ production rate and superoxide dismutase activity increased under NPs/MPs. • Dimethyl sulfoxide production was not affected by nano- and micro-plastics. [ABSTRACT FROM AUTHOR]

Arthrospira , commonly known as Spirulina in the commercial sector, is the most produced algae globally. A significant challenge in Arthrospira mass cultivation is zooplankton contamination, which might result in an annual loss of up to 30 % in biomass productivity if the zooplanktonic predation is not managed. This study, based on comprehensive field tests conducted in 1000 m2 raceway ponds, demonstrates the feasibility of using sodium dodecyl benzene sulfonate (SDBS) as a pesticide for managing zooplanktonic predators in Arthrospira mass cultivation. Under compensatory SDBS application, planktonic predators such as rotifers and ciliates are completely eliminated. This involves an initial application of SDBS at 15 mg L−1 followed by an additional enhancement of 5 mg L−1 after 24 h. Early detection of the contamination and apply the SDBS pesticide as soon as possible by a compensatory manner is beneficial for a better management of the contaminations. The findings provide a novel approach for managing zooplanktonic predations and ensuring efficient and sustainable production of Arthrospira. [Display omitted] • SDBS effectively eliminate rotifer and ciliate with minor impact on Arthrospira. • Field trials conducted in 1000 m2 raceway ponds favor the SDBS pesticide. • SDBS pesticide avoids the 30 % biomass loss in Arthrospira production. [ABSTRACT FROM AUTHOR]

Prostomateans, as common inhabitants in diverse aquatic environments, are among the simplest ciliate lineages, and serve as trophic links in food webs. However, only a few members are well-known and thoroughly studied, and the diversity of this group remains elusive. The unique genus Plagiocampa has a long history of research, but few studies have been performed using up-to-date methods. In the present work, Plagiocampa longis Kahl, 1927 and Plagiocampa minima Kahl, 1927, collected from Chinese coastal habitats, were investigated based on microscopical observation, protargol staining, and SSU rRNA gene sequencing. Their ciliature and morphometric data as well as gene sequences are documented. Phylogenetic analyses revealed that the family Plagiocampidae is likely monophyletic and has a closer relationship with parasitic Cryptocaryon. [ABSTRACT FROM AUTHOR]

Ciliates of the class Plagiopylea play a vital role in various anaerobic environments as consumers of prokaryotes. Yet, the diversity and phylogeny of this group of ciliates, especially marine representatives, remain poorly known. In this study, three Parasonderia species, viz., Parasonderia elongata spec. nov., and the already known P. cyclostoma and P. vestita , discovered in anaerobic sediments from various intertidal zones in China, were investigated based on their living morphology, infraciliature, and small subunit ribosomal rRNA gene sequences. Parasonderia elongata can be recognized by its larger body size, elongated body shape, oval oral opening, number of oral kineties, and significantly shortened leftmost postbuccal polykineties on the cell surface. Improved diagnosis and redescription of P. cyclostoma is provided for the first time, including data on infraciliature and molecular sequence. Phylogenetic analyses revealed that the three species cluster together and with the sequence of a Chinese population of P. vestita already present in the GenBank database, forming a robust clade. [ABSTRACT FROM AUTHOR]

• Supplementation of E-64 had no lethal effects on T. thermophila cultures. • E-64 is found to be non-toxic at 5 µM concentration for T. thermophila. • Protease activity of T. thermophila secretomes reduced against some substrates. • Use of E-64 increases the recombinant protein production efficiency in T. thermophila. • Use of E-64 may improve recombinant protein production extracellularly. Tetrahymena thermophila is an alternative organism for recombinant protein production. However, the production efficiency in T. thermophila is quite low mainly due to the rich cysteine proteases. In this study, we studied whether supplementation of the E-64 inhibitor to T. thermophila cultures increases the recombinant protein production efficiency without any toxic side effects. Our study showed that supplementation of E-64 had no lethal effects on T. thermophila cells in flask culture at 30 °C and 38 °C. In vitro protease activity analysis using secretome as protease enzyme source from E-64-supplemented cell cultures showed a reduced protein substrate degradation using bovine serum albumin, rituximab, and milk lactoglobulin proteins. E-64 also prevented proteolysis of the recombinantly produced and secreted TtmCherry2-sfGFP fusion protein at some level. This reduced inhibitory effect of E-64 could be due to genetic compensation of the inhibited proteases. As a result, the 5 µM concentration of E-64 was found to be a non-toxic protease inhibitory supplement to improve extracellular recombinant protein production efficiency in T. thermophila. This study suggests that the use of E-64 may increase the efficiency of extracellular recombinant protein production by continuously reducing extracellular cysteine protease activity during cultivation. [ABSTRACT FROM AUTHOR]

When the ciliate Spirostomum ambiguum is transected into two pieces, both fragments regenerate and proliferate. In the anterior fragments, which have lost their contractile vacuoles due to transection, new contractile vacuoles were formed at their posterior ends in a few minutes. When the cells were cut into three pieces, new contractile vacuoles were formed in the anterior and middle fragments, both at their posterior ends. Thus, the anterior-posterior axis of S. ambiguum was maintained after transection. Morphological repair, including the formation of the contractile vacuole, was also observed when only the anteriormost portion was transected to cut out a small fragment that did not contain part of the macronucleus. Scanning electron microscopy was performed to observe changes in the shape of the cleavage surface of S. ambiguum during the wound healing process. Within minutes after cutting, the cut surface was covered with a cilia-free membrane, preventing leakage of cytoplasmic contents. The surface of the cut area then rounded with time and was covered with cilia, completing the repair of the cut area in about one day. [ABSTRACT FROM AUTHOR]

Osmoregulation is the homeostatic mechanism essential for the survival of organisms in hypoosmotic and hyperosmotic conditions. In freshwater or soil dwelling protists this is frequently achieved through the action of an osmoregulatory organelle, the contractile vacuole. This endomembrane organelle responds to the osmotic challenges and compensates by collecting and expelling the excess water to maintain the cellular osmolarity. As compared with other endomembrane organelles, this organelle is underappreciated and under-studied. Here we review the reported presence or absence of contractile vacuoles across eukaryotic diversity, as well as the observed variability in the structure, function, and molecular machinery of this organelle. Our findings highlight the challenges and opportunities for constructing cellular and evolutionary models for this intriguing organelle. [ABSTRACT FROM AUTHOR]

[Display omitted] • T. thermophila has 121 papain-family cysteine protease encoding genes. • TtPFCPs were divided into four distinct subgroups CATL, CATB, CATC, and CATX. • The majority of true TtPFCPs (96 out of the total) were in TtCATL subgroup. • Phylogenetic analysis showed that ciliate's PFCPs have ancestral features. • The results may help researchers to construct TtPFCP's KO mutants in T. thermophila. Tetrahymena thermophila is a promising host for recombinant protein production, but its utilization in biotechnology is mostly limited due to the presence of intracellular and extracellular papain-family cysteine proteases (PFCPs). In this study, we employed bioinformatics approaches to investigate the T. thermophila PFCP genes and their encoded proteases (TtPFCPs), the most prominent protease family in the genome. Results from the multiple sequence alignment, protein modeling, and conserved motif analyses revealed that all TtPFCPs showed considerably high homology with mammalian cysteine cathepsins and contained conserved amino acid motifs. The total of 121 TtPFCP-encoding genes, 14 of which were classified as non-peptidase homologs, were found. Remaining 107 true TtPFCPs were divided into four distinct subgroups depending on their homology with mammalian lysosomal cathepsins: cathepsin L-like (TtCATLs), cathepsin B-like (TtCATBs), cathepsin C-like (TtCATCs), and cathepsin X-like (TtCATXs) PFCPs. The majority of true TtPFCPs (96 out of the total) were in TtCATL-like peptidase subgroup. Both phylogenetic and chromosomal localization analyses of TtPFCPs supported the hypothesis that TtPFCPs likely evolved through tandem gene duplication events and predominantly accumulated on micronuclear chromosome 5. Additionally, more than half of the identified TtPFCP genes are expressed in considerably low quantities compared to the rest of the TtPFCP genes, which are expressed at a higher level. However, their expression patterns fluctuate based on the stage of the life cycle. In conclusion, this study provides the first comprehensive in-silico analysis of TtPFCP genes and encoded proteases. The results would help designing an effective strategy for protease knockout mutant cell lines to discover biological function and to improve the recombinant protein production in T. thermophila. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract Several challenges need to be overcome for algal biofuels to become economically viable alternative to fossil fuels. The major bottleneck is that it requires continuous production of large quantities of algal biomass at a very low cost. To achieve this algal crops have to be stably cultivated round the year in open ponds at a sufficiently high density. Currently, it is highly difficult as algae crops cultivated in the open ponds are prone to numerous abiotic & biotic stresses, which lead to frequent culture crashes and productivity losses. Abiotic stress can be managed largely through bio prospecting, screening and selection of right kind of algal strains for that geographic location & season. Managing contaminants in open ponds along with maintaining productivity of algal crop to match the economics of biofuel production has so far proved to be an insurmountable barrier worldwide. The technologies successfully used till date to manage competition or grazing in open ponds have proved unsuccessful as these methods either limit desired productivity or are incompatible for prospective candidate algal strains ideal for fuel production. In the present study, we have taken a holistic approach starting from isolation, identification and characterization of major grazers associated with our algal crop and in parallel screening of several chemicals those could limit grazers in ponds. This was followed by testing the identified chemicals on the grazers, determining the sensitivity of our production strain to the chemicals found effective against grazers and finally providing chemistries that are able to eradicate the pests in open ponds with no adverse effects on our crop. Importantly this study reports 40 chemical candidates that are effective against grazers and can be utilized to prevent grazing during algae cultivation depending upon their compatibility with the algae strain grown. Highlights • Isolation, identification and phylogenetic characterization of grazers in outdoor ponds cultivated with Chlorella vulgaris. • A large number of varied chemicals screened for their efficiency in controlling the grazers, ciliates and dinoflagellates. • Several chemicals effective against the grazers were low cost and compatible with the production strain, C. vulgaris. • Successful application of one of these chemicals in recovering a crashed pond of Chlorella vulgaris infected with ciliates. • 40 chemicals have potent anti-grazer activity and can utilized during cultivation of different algal strains. [ABSTRACT FROM AUTHOR]

Industrial wastewater is of particular importance. In most wastewater treatments, physicochemical parameters are used to determine the performances which are costly while protozoa can be used as less expensive biological indicators to determine the efficiency of the treatment plant. The purpose of this study was to investigate the relationship between protozoa and physic-chemical characteristics of the Abadan wastewater treatment industry. Samples were collected from wastewater stabilization ponds in the Abadan industrial park. A total of 66 samples for biochemical and chemical tests and protozoa counts were taken. The sites of sampling were influent of sewage and effluent from maturation pond. For the parameters from influent, first 300 mL of samples was collected in depths of 0.1, 0.35 and 1 m and then mixed to provide a composite sample. 300 mL sample was directly taken from the effluent. The results of this study indicate that there is a positive relationship between the number and population percentage of amoeba and mastigophora (flagellate) with BOD and COD, whereas is the negative relationship between sticking ciliates with BOD and COD. Furthermore there is a positive relation between DO, the percentage, number of ciliates and amoeba population and there is a correlation, with flagellate population. Increase of flagellate numbers is indicative of high effluent Kjeldahl nitrogen. There was also an increase of input TSS and amoeba population percentage and a reduction of free ciliates numbers. The type and abundance of protozoa in industrial wastewater treatment following biological methods is an indicator of the system performance and effluent quality. This study shows the use of biological indicators can be used for monitoring as a much cheaper alternative resulting in a better economy. It is also a good indicator for the detection of toxic materials entering the plant or refinery and also its organic load shocks. [ABSTRACT FROM AUTHOR]

The aim of the present article is to analyse the evolutionary links between protozoa and neuronal and neurosecretory cells. To this effect we employ functional and topological data available for ciliates, in particular for Paramecium . Of note, much less data are available for choanoflagellates, the progenitors of metazoans, which currently are in the focus of metazoan genomic data mining. Key molecular players are found from the base to the highest levels of eukaryote evolution, including neurones and neurosecretory cells. Several common fundamental mechanisms, such as SNARE proteins and assembly of exocytosis sites, GTPases, Ca 2+ -sensors, voltage-gated Ca 2+ -influx channels and their inhibition by the forming Ca 2+ /calmodulin complex are conserved, albeit with different subcellular channel localisation, from protozoans to man. Similarly, Ca 2+ -release channels represented by InsP 3 receptors and putative precursors of ryanodine receptors, which all emerged in protozoa, serve for focal intracellular Ca 2+ signalling from ciliates to mammalian neuronal cells, eventually in conjunction with store-operated Ca 2+ -influx. Restriction of Ca 2+ signals by high capacity/low affinity Ca 2+ -binding proteins is maintained throughout the evolutionary tree although the proteins involved differ between the taxa. Phosphatase 2B/calcineurin appears to be involved in signalling and in membrane recycling throughout evolution. Most impressive example of evolutionary conservation is the sub-second dynamics of exocytosis-endocytosis coupling in Paramecium cells, with similar kinetics in neuronal and neurosecretory systems. Numerous cell surface receptors and channels that emerge in protozoa operate in the human nervous system, whereas a variety of cell adhesion molecules are newly “invented” during evolution, enabled by an increase in gene numbers, alternative splice forms and transcription factors. Thereby, important regulatory and signalling molecules are retained as a protozoan heritage. [ABSTRACT FROM AUTHOR]

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Mating pheromones (gamone 1 and gamone 2) in the ciliate Blepharisma are biologically active substances that trigger sexual reproduction (conjugation) under starvation conditions. Gamone 1 is a glycoprotein secreted by type I cells, and gamone 2 is a tryptophan (Trp)-derivative compound secreted by type II cells. Both gamones stimulate complementary mating type cells to promote each gamone production and induce pair formation. To elucidate the biosynthetic pathway of gamone 2, we investigated the enzymes involved in the pathway and the specificity of the enzymes. An RNA-seq analysis revealed that Blepharisma stoltei (Heterotrichea) possesses four indoleamine 2,3-dioxygenase ( IDO ) genes showing distinct expression patterns. Along with results from real-time PCR, these findings demonstrated that each IDO gene has different expression patterns that depend on the cellular conditions. Expression of IDO-I was correlated with the intensity of gamone 2 expression, and the recombinant IDO-I protein showed catalytic activity for 5-hydroxy-L-Trp (5-HTP) but very weak activity for L-Trp. Our results indicate that IDO-I is an enzyme evolutionary specialized to gamone 2 production in Blepharisma , and that the biosynthetic pathway for gamone 2 uses 5-HTP as an intermediate. [ABSTRACT FROM AUTHOR]

[Display omitted] The transition from growth to division during the cell cycle encompasses numerous conserved processes such as large-scale DNA replication and protein synthesis. In ciliate cells, asexual cell division is accompanied by additional cellular changes including amitotic nuclear division, extensive ciliogenesis, and trichocyst replication. However, the molecular mechanisms underlying these processes remain elusive. In this study, we present single-cell gene expression profiles of Paramecium cf. multimicronucleatum cells undergoing cell division. Our results reveal that the most up-regulated genes in dividing cells compared to growing cells are associated with 1) cell cycle signaling pathways including transcription, DNA replication, chromosome segregation and protein degradation; 2) microtubule proteins and tubulin glycylases which are essential for ciliogenesis, nuclei separation and structural differentiation signaling; and 3) trichocyst matrix proteins involved in trichocyst synthesis and reproduction. Furthermore, weighted gene co-expression network analysis identified hub genes that may play crucial roles during cell division. Our findings provide insights into cell cycle regulators, microtubules and trichocyst matrix proteins that may exert influence on this process in ciliates. [ABSTRACT FROM AUTHOR]

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 (≥ 5 mg/L) and B[ a ]P (≥ 50.5 μg/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. [ABSTRACT FROM AUTHOR]

Morphogenesis in the soil hypotrich ciliate, Rigidohymena quadrinucleata (Dragesco and Njine, 1971) Berger, 2011; was investigated using protargol staining. The main events during binary fission are as follows: (1) the proter retains the parental adoral zone of membranelles entirely, whereas the old undulating membranes dedifferentiate into an anlage that gives rise to the leftmost frontal cirrus and the new undulating membranes of the proter; (2) six streaks of frontoventral-transverse cirral anlagen are segmented in the pattern 1:3:3:3:4:4 from left to right, which form three frontal, four frontoventral, one buccal, five ventral and five transverse cirri, respectively; (3) the postoral ventral cirrus V/3 is not involved in primordia formation demonstrating that this species belongs to the stylonychines; (4) marginal anlagen are formed intrakinetally and the right marginal anlagen develop much earlier than the left ones; (5) the generation of the dorsal kineties is of typical Oxytricha -pattern and 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 sequence data indicate that Rigidohymena is polyphyletic and that R. quadrinucleata clusters with R. candens with full support. [ABSTRACT FROM AUTHOR]

Pleurotricha oligocirrata nov. spec. was discovered in samples collected from a freshwater wetland in Korea and is described here based on its morphology, morphogenesis, and the nucleotide sequence of its nuclear small subunit ribosomal rRNA (SSU rRNA) gene. In its genus, P. oligocirrata is the only species that possesses one right marginal cirral row. The morphology of P. oligocirrata is as follows: body size 98–148 × 47–72 μm in protargol preparations, colourless and rigid body; contractile vacuole anterior of mid-body near left margin; cortical granules lacking; two macronuclear nodules with two micronuclei; undulating membranes in Oxytricha pattern; 50–62 adoral membranelles, 23–27 frontal-ventral-transverse cirri, one left and one right marginal cirral row; six or seven dorsal kineties, including dorsomarginal rows, with three caudal cirri. The genetic distances between P. oligocirrata and its congeners P. curdsi and P. lanceolata were 0.257%–0.386% (4–6 nt difference) and 0.064% (1 nt difference), respectively. [ABSTRACT FROM AUTHOR]

N 6 -methyladenine DNA (6mA) modification exists in both prokaryotes and eukaryotes in which it plays a crucial role in regulating numerous biological processes. In prokaryotes, 6mA is a marker to distinguish self from foreign DNA. Its role in eukaryotes, however, remains elusive. Ciliates were among the first eukaryotes reported to contain 6mA. In the model organism T. thermophila , cellular localization and features of 6mA have been extensively studied, especially in ribosomal DNA (rDNA) molecules. Here, we summarize the features and potential functions of 6mA in Tetrahymena thermophila and other ciliates, and the major findings and contributions of the Tetrahymena model in studies of 6mA methylation. We also discuss other questions in order to improve understanding of the function and evolution of 6mA in eukaryotes. [ABSTRACT FROM AUTHOR]

Biological soil crusts (BSC) are associations of different macro and microorganisms and aggregated soil particles located on the surface of soils in many different habitats. BSC harbour a diverse and complex community of ciliates and testate amoebae. These phagotrophic protists play an important role in C and N recycling in soil ecosystems but have not been frequently studied in BSC. In this context, the effects of three increasing N inputs on ciliates and testate amoebae in crusts from a semi-arid Mediterranean ecosystem were evaluated. A field experiment with artificial N-deposition was designed to mimic the effects caused by anthropogenic N depositions. The results have shown that the protist populations of these semi-arid Mediterranean environments have lower species richness than other soil environments. The increase in N produces a net loss of diversity in the populations studied and shifts in the community structure. It has also been shown that some ciliates and testate amoebae, due to their population responses to increased N concentrations, could potentially be used as bio-indicators of N contamination in these BSCs. [ABSTRACT FROM AUTHOR]

Toxic effects of diuron and carbofuran on Paramecium caudatum were evaluated. Acute and chronic tests were conducted with diuron and carbofuran active ingredients and their commercial formulations, Diuron Nortox ® 500 SC and Furadan ® 350 SC, respectively. The sensitivity range of P. caudatum to reference substance sodium chloride was established. A preliminary risk assessment of diuron and carbofuran for Brazilian water bodies was performed. The tests indicated that toxicity of pure diuron and its commercial formulation was similar, while the commercial product carbofuran was more toxic than its pure form. In acute tests, readings were carried out at 2, 3, 4 and 6 h and showed an increase of mortality with increasing exposure time. The sensitivity of P. caudatum to NaCl ranged from 3.31 to 4.44 g L −1 , averaging 3.88 g L −1 . For diuron, the 6 h LC 50 was 64.6 ± 3.3 mg L −1 for its pure form and 62.4 ± 2.5 mg L −1 for its commercial formulation. Carbofuran active ingredient was less toxic than that of diuron, presenting a 6 h LC 50 of 142.0 ± 2.4 mg L −1 for its pure form and 70.4 ± 2.2 mg L −1 for its commercial product. Chronic tests showed that these pesticides cause significant decrease on population growth, generation number and biomass of P. caudatum . The 24 h IC 50 was 7.10 ± 0.58 mg L −1 for pure diuron, 6.78 ± 0.92 mg L −1 for commercial diuron, 22.95 ± 3.57 mg L −1 for pure carbofuran and 4.98 ± 0.62 mg L −1 for commercial carbofuran. Preliminary risk assessment indicated that diuron and carbofuran present potential ecological risks for Brazilian water bodies. P. caudatum was a suitable and sensitive test organism to evaluate diuron and carbofuran toxicity to freshwater protozooplankton and, taking into account the relevant role of protozoans in aquatic environments, we strongly recommend its inclusion in ecotoxicological studies. [ABSTRACT FROM AUTHOR]

Many freshwater protists harbor unicellular green algae within their cells, but little is known of their degree of integration and specificity. Using algae-targeted PCR of whole ciliate cells collected at irregular intervals over 15 months from Lake Biwa, Japan, we explored the SSU-ITS rDNA of the endosymbiotic algae and its changes over time, obtaining sequences of algal rDNA fragments from four ciliate species. A high proportion of clonal algae was evident within the ciliate cells. The differences observed in those sequences from the SSU through to the ITS region were less than 1%. The name ‘Chlorb’ is proposed for these algae, with the implication that they represent a single ‘species.’ The sequences of the algal DNA fragments were identical for any given host species throughout the collection period, thus we conclude that these four ciliates stably retain their algae over long term. In contrast, algal DNA fragments obtained from Didinium sp. were variable within each sample, which indicates that this ciliate only temporarily holds its algal cells. The ITS1 sequences of Chlorb populations are close (at intraspecific level) to those of algae isolated from ciliates in Austria, which raises the possibility that Chlorb algae are universally shared as symbionts among various ciliates. [ABSTRACT FROM AUTHOR]

Copyright of Parasite (1252607X) is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The morphology and molecular phylogeny of a new soil ciliate, Keronopsis koreana n. sp., which was discovered in soil from Jindo-gun, South Korea, were investigated. The new species is characterized by the following morphological features: cell more or less ellipsoid or ovoid, both ends broadly rounded; cortical granules irregularly distributed, colorless, 1 µm across; 35–54 adoral membranelles; 12–23 cirri in frontal corona; two frontal and two frontoventral cirral rows; two or three buccal cirri; 23–38 left and 22–37 right marginal cirri; three bipolar dorsal kineties; and two macronuclear nodules and three to five micronuclei. Phylogenetic analyses show that Keronopsis koreana n. sp. is placed within a clade containing K. helluo (type species of Keronopsis) and species belonging to Paraholosticha , Uroleptoides , Parabistichella , Orthoamphisiella , Lamtostyla , and Bistichella in non-dorsomarginalian hypotrichs. Also, the sequences belonging to the Keronopsidae did not cluster together. In addition, a new combination is provided: Parabistichella tasmaniensis (Blatterer and Foissner, 1988) n. comb. (original combination: Keronopsis tasmaniensis). [ABSTRACT FROM AUTHOR]

[Display omitted] • First ultrastructural study of a tintinnid resting cyst. • Three wall layers differing in texture and nitrogen content. • Kinetosome-resorbing tintinnid cyst with emergence pore. • Revision of taxonomically relevant cyst features. Resting cysts protect ciliates against adverse environmental conditions. The morphology and ultrastructure of resting cysts has been described in very few Oligotrichea, a group of mainly marine planktonic ciliates. The present study provides the first ultrastructural data for loricate choreotrichids, applying light and electron microscopy on the cysts of the tintinnid Schmidingerella meunieri (Kofoid and Campbell, 1929) Agatha and Strüder-Kypke, 2012. The morphology of live cysts and the wall ultrastructure of cryofixed cysts were morphometrically analysed. The resting cyst is roughly flask-shaped, broadening to a slightly concave, laterally protruding anterior plate. An emergence pore closed by a skull cap-shaped papula is directed to the bottom of the lorica on the opposite side of the cyst. The cyst wall consists of an ectocyst, mesocyst, and endocyst differing in thickness, structure, and nitrogen concentration as revealed by conventional transmission electron microscopy, electron energy loss spectroscopy, and electron spectroscopic imaging. The cysts of S. meunieri belong to the kinetosome-resorbing type, which also occurs in the majority of hypotrich ciliates. Two main features (flask-shape and presence of an emergence pore) are shared with the closely related aloricate choreotrichids and oligotrichids, distinguishing the Oligotrichea from the hypotrich and the more distantly related euplotid ciliates. [ABSTRACT FROM AUTHOR]

The Paramecium tetraurelia cell is highly organised, with regularly spaced elements pertinent to Ca 2+ signalling under epigenetic control. Vesicles serving as stationary Ca 2+ stores or undergoing trafficking contain Ca 2+ -release channels ( Pt CRCs) which, according to sequence and domain comparison, are related either to inositol 1,4,5-trisphosphate (InsP 3 ) receptors (IP 3 R) or to ryanodine receptor-like proteins (RyR-LP) or to both, with intermediate characteristics or deviation from conventional domain structure. Six groups of such Pt CRCs have been found. The ryanodine-InsP 3 -receptor homology (RIH) domain is not always recognisable, in contrast to the channel domain with six trans-membrane domains and the pore between transmembrane domain 5 and 6. Two CRC subtypes tested more closely, Pt CRC-II and Pt CRC-IV, with and without an InsP 3 -binding domain, reacted to InsP 3 and to caffeine, respectively, and hence represent IP 3 Rs and RyR-LPs. IP 3 Rs occur in the contractile vacuole complex where they allow for stochastic constitutive Ca 2+ reflux into the cytosol. RyR-LPs are localised to cortical Ca 2+ stores; they are engaged in dense core-secretory vesicle exocytosis by Ca 2+ release, superimposed by Ca 2+ -influx via non-ciliary Ca 2+ -channels. One or two different types of Pt CRCs also occur in other vesicles undergoing trafficking. Since the Pt CRCs described combine different features they are considered derivatives of primitive precursors. The highly regular, epigenetically controlled design of a Paramecium cell allows it to make Ca 2+ available very locally, in a most efficient way, along predetermined trafficking pathways, including regulation of exocytosis, endocytosis, phagocytosis and recycling phenomena. The activity of cilia is also regulated by Ca 2+ , yet independently from any CRCs, by de- and hyperpolarisation of the cell membrane potential. [ABSTRACT FROM AUTHOR]

The ciliated protozoan, Paramecium tetraurelia has a high basic Ca 2+ leakage rate which is counteracted mainly by export through a contractile vacuole complex, based on its V-type H + -ATPase activity. In addition Paramecium cells dispose of P-type Ca 2+ -ATPases, i.e. a plasmamembrane and a sarcoplasmic/endoplasmic reticulum Ca 2+ -ATPase (PMCA, SERCA). Antiporter systems are to be expected, as inferred from indirect evidence. Among the best known cytosolic Ca 2+ -binding proteins, calmodulin activates Ca 2+ influx channels in the somatic cell membrane, but inactivates Ca 2+ influx channels in cilia, where it, thus, ends ciliary reversal induced by depolarization via channels in the somatic cell membrane. Centrin inactivates Ca 2+ signals after stimulation by its high capacity/low affinity binding sites, whereas its high affinity sites regulate some other functions. Cortical Ca 2+ stores (alveolar sacs) are activated during stimulated trichocyst exocytosis and thereby mediate store-operated Ca 2+ entry (SOCE). Ca 2+ release channels (CRCs) localised to alveoli and underlying SOCE are considered as Ryanodine receptor-like proteins (RyR-LPs) which are members of a CRC family with 6 subfamilies. These also encompass genuine inositol 1,4,5-trisphosphate receptors (IP 3 Rs) and intermediates between the two channel types. All IP 3 R/RyR-type CRCs possess six carboxyterminal transmembrane domains (TMD), with a pore domain between TMD 5 and 6, endowed with a characteristic selectivity filter. There are reasons to assume a common ancestor molecule for such channels and diversification further on in evolution. The distinct distribution of specific CRCs in the different vesicles undergoing intracellular trafficking suggests constitutive formation of very locally restricted Ca 2+ signals during vesicle–vesicle interaction. In summary, essential steps of Ca 2+ signalling already occur at this level of evolution, including an unexpected multitude of CRCs. For dis-/similarities with other bikonts see “Conclusions”. [ABSTRACT FROM AUTHOR]

We aimed to freeze-dry the ciliate Spirostomum ambiguum , obtained from water, without fixation and observe it using scanning electron microscopy (SEM). Living cells were placed on a specimen stub and frozen upon contact with a Cu block kept at either −80 °C or −100 °C. Samples were then freeze-dried and observed by SEM. In most cases, no damage to the specimen due to ice crystal formation was observed. Because of the instantaneous freezing, the metachronal wave of cilia on the body surface of the ciliate was well preserved. Approximately 70–80% of cells were preserved in the contracted state due to inevitable exposure to mechanical vibration immediately before freezing. The remaining samples were preserved in a fully-extended state. Morphometric measurements of the cell surface showed that in the extended state, ciliary rows were almost parallel to the long axis of the cell, whereas in the contracted state, they were twisted in a left-handed helix at an angle of 45–65°. The distance between adjacent cilia along a ciliary row was 1.88 ± 0.43 μm in the extended state and 1.32 ± 0.41 μm in the contracted state (mean ± SD). However, the spacing between adjacent ciliary rows remained unchanged. [ABSTRACT FROM AUTHOR]

Ciliates are unique in having nuclear dimorphism (i.e., possessing both a germline micronucleus and a somatic macronucleus in one cell), and undergo dramatic changes during their sexual process (known as conjugation). Here we investigate the nuclear events and morphogenetic processes during conjugation in the freshwater species Euplotes aediculatus. In addition, three conjugation-related pheromone genes were sequenced and analyzed. The results indicate that: (i) the 65-hour-long conjugation process includes five nuclear divisions, i.e., three prezygotic divisions (mitosis, meiosis I and II) and two postzygotic divisions; (ii) the ciliature reorganizes twice during conjugation with the frontoventral-transverse cirral anlagen regenerating during both morphogenetic events and breaking apart in a 3:3:3:2:2 pattern; and (iii) each of three pheromone genes contains a 444 bp coding region and encodes 147 amino acid polypeptides. These results suggest a broadly shared morphogenetic pattern during conjugation in Euplotes species and provide new information for studies on the evolutionary history of pheromone genes. [ABSTRACT FROM AUTHOR]

In some ciliates, extensive genome fragmentation leads to a macronucleus (i.e. somatic nucleus) containing gene-sized chromosomes that vary in copy number. Yet the relationship between copy number and expression level is not well understood as previous work has shown a variety of patterns. For example, nanochromosome copy numbers are positively correlated to mRNA levels in spirotrichous ciliates, while one study of Chilodonella uncinata suggested that they were inversely correlated. To study further copy number and expression levels in C. uncinata , we analyzed 11 members in five gene families (SSU-rDNA, actin, alpha-tubulin, histidine acid phosphatase family protein and a protein kinase domain containing protein) from one strain. We find that macronuclear copy numbers of these genes range from hundreds to thousands per cell, and that copy number does not correlate with expression level as measured by steady-state RNA in predominantly-vegetative cultures. We also compared six of these genes to their orthologs in a second genetically-isolated strain of C. uncinata to reveal that patterns of nanochromosome and transcript copy numbers are conserved between strains. Our data suggest that nanochromosome copy number may be related to a feature like nuclear architecture. [ABSTRACT FROM AUTHOR]

Abstract: The novel ciliate Platynematum salinarum (Scuticociliatia) was isolated only recently from a thalassohaline solar saltern pond (12%) in Portugal. Scanning electron microscopy showed numerous bacterial-shaped cells covering the complete surface of the ciliate. The rod-shaped epibionts were identified and characterized following the “Full-Cycle rRNA Approach”. The almost full-length 16S rRNA gene sequence was obtained using archaeal-specific primers and two species-specific probes were designed for fluorescence in situ hybridization. The 16S rRNA gene sequence of the epibiotic cells showed 87% sequence identity with the type strain sequence of the closest characterized species Halolamina pelagica. Phylogenetic reconstructions affiliated the novel organism to the genus Halolamina (Halobacteria, Archaea). Attempts to isolate the epibionts failed and, therefore, growth experiments incorporating the antibiotic anisomycin were conducted in order to investigate the potential symbiotic relationship between P. salinarum and the epibionts. The results suggested an obligate symbiosis between the two organisms and revealed the first symbiotic representative of the Halobacteria. Based on the phylogenetic analyses and growth experiments we propose the classification of this novel organism in a new genus, with the taxon name “Candidatus Haloectosymbiotes riaformosensis”. [Copyright &y& Elsevier]

Abstract: We investigate the living morphology, infraciliature, and small subunit rRNA gene sequences of two poorly known marine euplotids, Aspidisca fuscaKahl, 1928 and A. hexerisQuennerstedt, 1869, isolated from intertidal sewage outfall, northern China and sandy sediments, southern China, respectively. Improved diagnoses and morphometric data are provided for both species. Aspidisca fusca is characterized by having a peristomial spur, seven frontoventral cirri in a “polystyla-arrangement”, and two oval macronuclear nodules. Aspidisca hexeris can be recognized by having an elliptical body shape, a peristomial spur, seven membranelles in the anterior portion of adoral zone and 11–13 in the posterior part, as well as seven frontoventral cirri arranged in two oblique rows. In addition, the presence and degree of projections along the left margin of A. hexeris are highly variable among populations. Phylogenetic analyses based on small subunit rRNA gene sequence data support the validity of both A. hexeris and A. fusca as distinct species, and indicate that A. fusca is most closely related to A. aculeata and A. steini, whereas A. hexeris shows a close relationship with A. magna. [Copyright &y& Elsevier]

Abstract: The occurrence of ∑HCHs, ∑DDTs, protozoa abundance and their community structure in surface soils of orchards, vegetable lands, and barren lands in northern west outskirts of Beijing were detected in order to investigate the protozoa responses to low dose organic chlorinated Pesticides (OCPs) after long-term field-based exposure. Significant differences in total concentrations of HCHs and DDTs were found among the three general groups ranking in decreasing order of concentration from orchard>vegetable lands >barren lands. Ciliate was the rare group in surface soils of all the sampling groups. The abundance of flagellate, ciliate, and amoebae in vegetable soils were significantly higher than those in orchard soils. The abundance of all the taxa of protozoa was strongly negative correlated with the residue level of ∑HCHs and ∑DDTs (P<0.05) in agricultural soils. However, no negative correlation between the residue levels of OCPs and protozoa abundance was shown in both the orchard and the barren soils. This field study demonstrated a considerable long-term impact of the OCPs residue on the abundance of protozoa in soils, and that the abundance of soil protozoa was much more influenced by land use type in association with different soil properties. [Copyright &y& Elsevier]

Abstract: The contractile vacuole complex (CVC) of freshwater protists serves the extrusion of water and ions, including Ca2+. No vesicle trafficking based on SNAREs has been detected so far in any CVC. SNAREs (soluble NSF [N-ethylmaleimide sensitive factor] attachment protein receptors) are required for membrane-to-membrane interaction, i.e. docking and fusion also in Paramecium. We have identified three v-/R- and three t/Q-SNAREs selectively in the CVC. Posttranscriptional silencing of Syb2, Syb6 or Syx2 slows down the pumping cycle; silencing of the latter two also causes vacuole swelling. Increase in extracellular Ca2+ after Syb2, Syb6 or Syx2 silencing causes further swelling of the contractile vacuole and deceleration of its pulsation. Silencing of Syx14 or Syx15 entails lethality in the Ca2+ stress test. Thus, the effects of silencing strictly depend on the type of the silenced SNARE and on the concentration of Ca2+ in the medium. This shows the importance of organelle-resident SNARE functions (which may encompass the vesicular delivery of other organelle-resident proteins) for Ca2+ tolerance. A similar principle may be applicable also to the CVC in widely different unicellular organisms. In addition, in Paramecium, silencing particularly of Syx6 causes aberrant positioning of the CVC during de novo biogenesis before cytokinesis. [Copyright &y& Elsevier]

Concentrations of metals associated with sediments have traditionally been analysed to assess the extent of heavy metal contamination in freshwater environments. Stream biofilms present an alternative medium for this assessment which may be more relevant to the risk incurred by stream ecosystems as they are intensively grazed by aquatic organisms at a higher trophic level. Therefore, we investigated zinc, copper and lead concentrations in biofilms and sediments of 23 stream sites variously impacted by urbanisation. Simultaneously, biofilm bacterial and ciliate protozoan community structure was analysed by Automated Ribosomal Intergenic Spacer Analysis and Terminal Restriction Fragment Length Polymorphism, respectively. Statistical analysis revealed that biofilm associated metals explained a greater proportion of the variations observed in bacterial and ciliate communities than did sediment associated-metals. This study suggests that the analysis of metal concentrations in biofilms provide a good assessment of detrimental effects of metal contaminants on aquatic biota. [Copyright &y& Elsevier]

Abstract: Apostome ciliates from crayfish and freshwater shrimp in southern and central Alabama were surveyed in this study. Hyalophysa bradburyae was found on both crayfish and shrimp from 16 sites in eight drainages. A new species, Hyalophysa clampi n. sp., was found infesting crayfish at one site and simultaneously infesting crayfish with H. bradburyae at two sites. Characteristics of the trophont ciliature of H. clampi n. sp. separate it from other species in the genus. Particularly, the contractile vacuole pore is oriented posterior to the ventral kineties xyz, kineties 1 and 2 are undivided, an apparent second contractile vacuole pore is present between the ventral portions of kineties 1 and 2, the anterior ventral field is tightly arranged, and there is an apical field of kineties between kineties 4 through 6. This report expands the known range and diversity of the genus Hyalophysa in the state of Alabama. [Copyright &y& Elsevier]

Oxytricha trifallax — an established model organism for studying genome rearrangements, chromosome structure, scrambled genes, RNA-mediated epigenetic inheritance, and other phenomena — has been the subject of a nomenclature controversy for several years. Originally isolated as a sibling species of O. fallax, O. trifallax was reclassified in 1999 as Sterkiella histriomuscorum, a previously identified species, based on morphological similarity. The proper identification of O. trifallax is crucial to resolve in order to prevent confusion in both the comparative genomics and the general scientific communities. We analyzed nine conserved nuclear gene sequences between the two given species and several related ciliates. Phylogenetic analyses suggest that O. trifallax and a bona fide S. histriomuscorum have accumulated significant evolutionary divergence from each other relative to other ciliates such that they should be unequivocally classified as separate species. We also describe the original isolation of O. trifallax, including its comparison to O. fallax, and we provide criteria to identify future isolates of O. trifallax. [ABSTRACT FROM AUTHOR]

Oxytricha trifallax — an established model organism for studying genome rearrangements, chromosome structure, scrambled genes, RNA-mediated epigenetic inheritance, and other phenomena — has been the subject of a nomenclature controversy for several years. Originally isolated as a sibling species of O. fallax , O. trifallax was reclassified in 1999 as Sterkiella histriomuscorum, a previously identified species, based on morphological similarity. The proper identification of O. trifallax is crucial to resolve in order to prevent confusion in both the comparative genomics and the general scientific communities. We analyzed nine conserved nuclear gene sequences between the two given species and several related ciliates. Phylogenetic analyses suggest that O. trifallax and a bona fide S. histriomuscorum have accumulated significant evolutionary divergence from each other relative to other ciliates such that they should be unequivocally classified as separate species. We also describe the original isolation of O. trifallax , including its comparison to O. fallax , and we provide criteria to identify future isolates of O. trifallax . [ABSTRACT FROM AUTHOR]

In contrast to most ciliates, meiosis and successive nuclear changes during conjugation occur only in heterotypic pairs in Blepharisma. It has been suggested that homotypic pairs are ready for conjugation, but lack a trigger to initiate the nuclear changes, and the conjugation process is arrested before the onset of meiosis. To explore the possible nature of the trigger, we previously identified the genes BjCdk1 (homologous to cdk1/cdc2), Bj4HPPD (4-hydroxy-phenylpyruvate dioxygenase) and BjCks (cyclin dependent kinase regulatory subunit) whose expression is up-regulated in gamone1-treated type II cells. In this study, we investigated the molecular structures of these three genes, and compared their expression patterns in homotypic and heterotypic pairs, finding remarkable differences. BjCdk1, Bj4HPPD and BjCks were expressed specifically in gamone1-treated type II cells, but not in gamone2-treated type I cells. In heterotypic pairs, the expression of these genes stayed at the same level or gradually decreased throughout the entire process of conjugation, but it rapidly decreased and ceased after 10hours in homotypic pairs. These results indicate that some genes are expressed in a mating-type specific manner. Alternative gene expression in mating type I and type II cells and merging of individual factors in a heterotypic pair may induce nuclear changes including meiosis. [ABSTRACT FROM AUTHOR]

The article presents a study on the description of five new species of astome ciliates found in the digestive tract of Oligochata worms in Africa. The authors utilizes various techniques in the study which include vital staining, scanning electron microscopy and the staining of the nucleus through Diamidino Phenyl Indol (DAPI). They confirm the existence of Paracoelophrya and Dicoelophrya in the digestive tract of the African worms. They state that the study provides a better understanding on the taxonomy of the Metaracoelophryinae subfamily.

Abstract: The ciliate parasite Ichthyophthirius multifiliis (Ich) infects many freshwater fish, causing white spot disease that leads to heavy economic losses to aquaculture and ornamental industries. Despite its economic importance, molecular studies examining fundamental processes such as life stage regulation and infectivity have been scarce. In this study, we developed an oligo microarray platform using all available I. multifiliis expressed sequence tag (EST) information as well as probes designed through comparative genomics to other protozoa. Gene expression profiling for developmental and virulence factors was conducted using this platform. For the developmental study, the microarray was used to examine gene expression profiles between the three major life stages of Ich: infective theront, parasitic trophont, and reproductive tomont. A total of 135 putative I. multifiliis genes were found to be differentially expressed among all three life-stages. Examples of differentially expressed transcripts among life stages include immobilization antigens and epiplasmin, as well as various other transcripts involved in developmental regulation and host-parasite interactions. I. multifiliis has been shown to lose infectivity at later cell divisions potentially due to cellular senescence. Therefore, the microarray was also used to explore expression of senescence-associated genes as related to the passage number of the parasite. In this regard, comparison between tomont early and late passages yielded 493 differently expressed genes; 1478 differentially expressed genes were identified between trophont early and late passages. The EST-derived oligo microarray represents a first generation array of this ciliate and provided reproducible expression data as validated by quantitative RT-PCR. [Copyright &y& Elsevier]

The article documents the parasite distribution and seasonality of four taxonomic groups that use the grass shrimp Palaemonetes pugio in Southwestern Alabama. It describes a regional survey of four symbionts of P. pugio over three seasons, finding the metacercarial stage of the microphallid trematode Microphallus turgidus as the most common parasite. Sites surrounding Mon Louis island were found to have higher parasite prevalence particularly in summer with its high quantity of marsh habitat.

Abstract: The ongoing climate change has motivated numerous studies investigating the temperature response of various organisms, especially that of ectotherms. To correctly describe the thermal performance of these organisms, functions are needed which sufficiently fit to the complete optimum curve. Surprisingly, model-comparisons for the temperature-dependence of population growth rates of an important ectothermic group, the protozoa, are still missing. In this study, temperature reaction norms of natural isolates of the freshwater protist Paramecium caudatum were investigated, considering nearly the entire temperature range. These reaction norms were used to estimate thermal performance curves by applying a set of commonly used model functions. An information theory approach was used to compare models and to identify the best ones for describing these data. Our results indicate that the models which can describe negative growth at the high- and low-temperature branch of an optimum curve are preferable. This is a prerequisite for accurately calculating the critical upper and lower thermal limits. While we detected a temperature optimum of around 29°C for all investigated clonal strains, the critical thermal limits were considerably different between individual clones. Here, the tropical clone showed the narrowest thermal tolerance, with a shift of its critical thermal limits to higher temperatures. [Copyright &y& Elsevier]

DNA barcoding using the mitochondrial cytochrome c oxidase subunit I (cox-1) gene has recently gained popularity as a tool for species identification of a variety of taxa. The primary objective of our research was to explore the efficacy of using cox-1 barcoding for species identification within the genus Tetrahymena . We first increased intraspecific sampling for Tetrahymena canadensis, Tetrahymena hegewischi, Tetrahymena pyriformis, Tetrahymena rostrata, Tetrahymena thermophila, and Tetrahymena tropicalis . Increased sampling efforts show that intraspecific sequence divergence is typically less than 1%, though it may be more in some species. The barcoding also showed that some strains might be misidentified or mislabeled. We also used cox-1 barcodes to provide species identifications for 51 unidentified environmental isolates, with a success rate of 98%. Thus, cox-1 barcoding is an invaluable tool for protistologists, especially when used in conjunction with morphological studies. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study which examined the behavioral interactions of calanoid copepod Temora turbinata with potential Ciliate prey. Images of Temoraciliate encounters were analyzed to calculate ciliate swimming trajectories, the attack kinematics of T. turbinata and reaction distances to the ciliates. The study found a wide variance in the reaction distances of T. turbinata in response to a swimming ciliate, however the ciliate was able to sense the copepod from a longer distance and escaped from the feeding current. It concluded that the copepod could differentiate between living and non-living organisms and expelled non-ingestible particles.

Entodinium constrictum was observed in rumen contents from a single sheep out of eleven living in Northern Cyprus. It constituted 0.08% of the total ciliate population and had a 9.09% frequency of appearance. The size and percentage occurrence of this species in the present study is compared to those previously reported for other animal hosts living in different geographical locations. This study reports for the first time the presence of E. constrictum in Cypriot domestic sheep. [ABSTRACT FROM AUTHOR]

Abstract: Polyadenylation of eukaryotic transcripts is usually restricted to mRNA, providing transcripts with stability from degradation by nucleases. Conversely, an RNA degradation pathway can be signaled through poly (A) tailing in prokaryotic, archeal, and organellar biology. Recently polyadenylated transcripts have also been discovered in rRNA in some eukaryotes including humans and yeast. Here we report the discovery of polyadenylated rRNAs in the ciliate teleost parasite Ichthyophthirius multifiliis, an important fish pathogen. Through large-scale analysis of ESTs, a large contig composed of the 28S rRNA with poly (A) tails was identified. Analysis using multiple sequence alignments revealed four potential polyadenylation sites including three internal regions and the 3′ end of the rRNA. Further analysis using a polyadenylation test, re-sequencing, and gene-specific PCR using primers flanking the presumed poly (A) sites confirmed the presence of polyadenylated rRNA in this parasite. The functions of polyadenylation of rRNA in this organism are largely unknown at present, but the presence of internal polyadenylation sites, along with the presence of truncated segments of the rRNA, may suggest a role of the polyadenylation in the degradation pathway, a function typical of prokaryotes, archaea, and organelles. These results are in congruence with reports of a similar phenomenon in humans and yeast. [Copyright &y& Elsevier]